Commit Graph

9440 Commits

Author SHA1 Message Date
Filipe Manana
3b87d0c583 btrfs: fix sleep while in non-sleep context during qgroup removal
commit 0bb788300990d3eb5582d3301a720f846c78925c upstream.

While removing a qgroup's sysfs entry we end up taking the kernfs_mutex,
through kobject_del(), while holding the fs_info->qgroup_lock spinlock,
producing the following trace:

  [821.843637] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:281
  [821.843641] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 28214, name: podman
  [821.843644] CPU: 3 PID: 28214 Comm: podman Tainted: G        W         5.11.6 #15
  [821.843646] Hardware name: Dell Inc. PowerEdge R330/084XW4, BIOS 2.11.0 12/08/2020
  [821.843647] Call Trace:
  [821.843650]  dump_stack+0xa1/0xfb
  [821.843656]  ___might_sleep+0x144/0x160
  [821.843659]  mutex_lock+0x17/0x40
  [821.843662]  kernfs_remove_by_name_ns+0x1f/0x80
  [821.843666]  sysfs_remove_group+0x7d/0xe0
  [821.843668]  sysfs_remove_groups+0x28/0x40
  [821.843670]  kobject_del+0x2a/0x80
  [821.843672]  btrfs_sysfs_del_one_qgroup+0x2b/0x40 [btrfs]
  [821.843685]  __del_qgroup_rb+0x12/0x150 [btrfs]
  [821.843696]  btrfs_remove_qgroup+0x288/0x2a0 [btrfs]
  [821.843707]  btrfs_ioctl+0x3129/0x36a0 [btrfs]
  [821.843717]  ? __mod_lruvec_page_state+0x5e/0xb0
  [821.843719]  ? page_add_new_anon_rmap+0xbc/0x150
  [821.843723]  ? kfree+0x1b4/0x300
  [821.843725]  ? mntput_no_expire+0x55/0x330
  [821.843728]  __x64_sys_ioctl+0x5a/0xa0
  [821.843731]  do_syscall_64+0x33/0x70
  [821.843733]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  [821.843736] RIP: 0033:0x4cd3fb
  [821.843741] RSP: 002b:000000c000906b20 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
  [821.843744] RAX: ffffffffffffffda RBX: 000000c000050000 RCX: 00000000004cd3fb
  [821.843745] RDX: 000000c000906b98 RSI: 000000004010942a RDI: 000000000000000f
  [821.843747] RBP: 000000c000907cd0 R08: 000000c000622901 R09: 0000000000000000
  [821.843748] R10: 000000c000d992c0 R11: 0000000000000206 R12: 000000000000012d
  [821.843749] R13: 000000000000012c R14: 0000000000000200 R15: 0000000000000049

Fix this by removing the qgroup sysfs entry while not holding the spinlock,
since the spinlock is only meant for protection of the qgroup rbtree.

Reported-by: Stuart Shelton <srcshelton@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/7A5485BB-0628-419D-A4D3-27B1AF47E25A@gmail.com/
Fixes: 49e5fb4621 ("btrfs: qgroup: export qgroups in sysfs")
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-30 14:31:53 +02:00
David Sterba
2c8d6a9474 btrfs: fix slab cache flags for free space tree bitmap
commit 34e49994d0dcdb2d31d4d2908d04f4e9ce57e4d7 upstream.

The free space tree bitmap slab cache is created with SLAB_RED_ZONE but
that's a debugging flag and not always enabled. Also the other slabs are
created with at least SLAB_MEM_SPREAD that we want as well to average
the memory placement cost.

Reported-by: Vlastimil Babka <vbabka@suse.cz>
Fixes: 3acd48507d ("btrfs: fix allocation of free space cache v1 bitmap pages")
CC: stable@vger.kernel.org # 5.4+
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-25 09:04:06 +01:00
Filipe Manana
38ffe9eaeb btrfs: fix race when cloning extent buffer during rewind of an old root
commit dbcc7d57bffc0c8cac9dac11bec548597d59a6a5 upstream.

While resolving backreferences, as part of a logical ino ioctl call or
fiemap, we can end up hitting a BUG_ON() when replaying tree mod log
operations of a root, triggering a stack trace like the following:

  ------------[ cut here ]------------
  kernel BUG at fs/btrfs/ctree.c:1210!
  invalid opcode: 0000 [#1] SMP KASAN PTI
  CPU: 1 PID: 19054 Comm: crawl_335 Tainted: G        W         5.11.0-2d11c0084b02-misc-next+ #89
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
  RIP: 0010:__tree_mod_log_rewind+0x3b1/0x3c0
  Code: 05 48 8d 74 10 (...)
  RSP: 0018:ffffc90001eb70b8 EFLAGS: 00010297
  RAX: 0000000000000000 RBX: ffff88812344e400 RCX: ffffffffb28933b6
  RDX: 0000000000000007 RSI: dffffc0000000000 RDI: ffff88812344e42c
  RBP: ffffc90001eb7108 R08: 1ffff11020b60a20 R09: ffffed1020b60a20
  R10: ffff888105b050f9 R11: ffffed1020b60a1f R12: 00000000000000ee
  R13: ffff8880195520c0 R14: ffff8881bc958500 R15: ffff88812344e42c
  FS:  00007fd1955e8700(0000) GS:ffff8881f5600000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007efdb7928718 CR3: 000000010103a006 CR4: 0000000000170ee0
  Call Trace:
   btrfs_search_old_slot+0x265/0x10d0
   ? lock_acquired+0xbb/0x600
   ? btrfs_search_slot+0x1090/0x1090
   ? free_extent_buffer.part.61+0xd7/0x140
   ? free_extent_buffer+0x13/0x20
   resolve_indirect_refs+0x3e9/0xfc0
   ? lock_downgrade+0x3d0/0x3d0
   ? __kasan_check_read+0x11/0x20
   ? add_prelim_ref.part.11+0x150/0x150
   ? lock_downgrade+0x3d0/0x3d0
   ? __kasan_check_read+0x11/0x20
   ? lock_acquired+0xbb/0x600
   ? __kasan_check_write+0x14/0x20
   ? do_raw_spin_unlock+0xa8/0x140
   ? rb_insert_color+0x30/0x360
   ? prelim_ref_insert+0x12d/0x430
   find_parent_nodes+0x5c3/0x1830
   ? resolve_indirect_refs+0xfc0/0xfc0
   ? lock_release+0xc8/0x620
   ? fs_reclaim_acquire+0x67/0xf0
   ? lock_acquire+0xc7/0x510
   ? lock_downgrade+0x3d0/0x3d0
   ? lockdep_hardirqs_on_prepare+0x160/0x210
   ? lock_release+0xc8/0x620
   ? fs_reclaim_acquire+0x67/0xf0
   ? lock_acquire+0xc7/0x510
   ? poison_range+0x38/0x40
   ? unpoison_range+0x14/0x40
   ? trace_hardirqs_on+0x55/0x120
   btrfs_find_all_roots_safe+0x142/0x1e0
   ? find_parent_nodes+0x1830/0x1830
   ? btrfs_inode_flags_to_xflags+0x50/0x50
   iterate_extent_inodes+0x20e/0x580
   ? tree_backref_for_extent+0x230/0x230
   ? lock_downgrade+0x3d0/0x3d0
   ? read_extent_buffer+0xdd/0x110
   ? lock_downgrade+0x3d0/0x3d0
   ? __kasan_check_read+0x11/0x20
   ? lock_acquired+0xbb/0x600
   ? __kasan_check_write+0x14/0x20
   ? _raw_spin_unlock+0x22/0x30
   ? __kasan_check_write+0x14/0x20
   iterate_inodes_from_logical+0x129/0x170
   ? iterate_inodes_from_logical+0x129/0x170
   ? btrfs_inode_flags_to_xflags+0x50/0x50
   ? iterate_extent_inodes+0x580/0x580
   ? __vmalloc_node+0x92/0xb0
   ? init_data_container+0x34/0xb0
   ? init_data_container+0x34/0xb0
   ? kvmalloc_node+0x60/0x80
   btrfs_ioctl_logical_to_ino+0x158/0x230
   btrfs_ioctl+0x205e/0x4040
   ? __might_sleep+0x71/0xe0
   ? btrfs_ioctl_get_supported_features+0x30/0x30
   ? getrusage+0x4b6/0x9c0
   ? __kasan_check_read+0x11/0x20
   ? lock_release+0xc8/0x620
   ? __might_fault+0x64/0xd0
   ? lock_acquire+0xc7/0x510
   ? lock_downgrade+0x3d0/0x3d0
   ? lockdep_hardirqs_on_prepare+0x210/0x210
   ? lockdep_hardirqs_on_prepare+0x210/0x210
   ? __kasan_check_read+0x11/0x20
   ? do_vfs_ioctl+0xfc/0x9d0
   ? ioctl_file_clone+0xe0/0xe0
   ? lock_downgrade+0x3d0/0x3d0
   ? lockdep_hardirqs_on_prepare+0x210/0x210
   ? __kasan_check_read+0x11/0x20
   ? lock_release+0xc8/0x620
   ? __task_pid_nr_ns+0xd3/0x250
   ? lock_acquire+0xc7/0x510
   ? __fget_files+0x160/0x230
   ? __fget_light+0xf2/0x110
   __x64_sys_ioctl+0xc3/0x100
   do_syscall_64+0x37/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7fd1976e2427
  Code: 00 00 90 48 8b 05 (...)
  RSP: 002b:00007fd1955e5cf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
  RAX: ffffffffffffffda RBX: 00007fd1955e5f40 RCX: 00007fd1976e2427
  RDX: 00007fd1955e5f48 RSI: 00000000c038943b RDI: 0000000000000004
  RBP: 0000000001000000 R08: 0000000000000000 R09: 00007fd1955e6120
  R10: 0000557835366b00 R11: 0000000000000246 R12: 0000000000000004
  R13: 00007fd1955e5f48 R14: 00007fd1955e5f40 R15: 00007fd1955e5ef8
  Modules linked in:
  ---[ end trace ec8931a1c36e57be ]---

  (gdb) l *(__tree_mod_log_rewind+0x3b1)
  0xffffffff81893521 is in __tree_mod_log_rewind (fs/btrfs/ctree.c:1210).
  1205                     * the modification. as we're going backwards, we do the
  1206                     * opposite of each operation here.
  1207                     */
  1208                    switch (tm->op) {
  1209                    case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
  1210                            BUG_ON(tm->slot < n);
  1211                            fallthrough;
  1212                    case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
  1213                    case MOD_LOG_KEY_REMOVE:
  1214                            btrfs_set_node_key(eb, &tm->key, tm->slot);

Here's what happens to hit that BUG_ON():

1) We have one tree mod log user (through fiemap or the logical ino ioctl),
   with a sequence number of 1, so we have fs_info->tree_mod_seq == 1;

2) Another task is at ctree.c:balance_level() and we have eb X currently as
   the root of the tree, and we promote its single child, eb Y, as the new
   root.

   Then, at ctree.c:balance_level(), we call:

      tree_mod_log_insert_root(eb X, eb Y, 1);

3) At tree_mod_log_insert_root() we create tree mod log elements for each
   slot of eb X, of operation type MOD_LOG_KEY_REMOVE_WHILE_FREEING each
   with a ->logical pointing to ebX->start. These are placed in an array
   named tm_list.
   Lets assume there are N elements (N pointers in eb X);

4) Then, still at tree_mod_log_insert_root(), we create a tree mod log
   element of operation type MOD_LOG_ROOT_REPLACE, ->logical set to
   ebY->start, ->old_root.logical set to ebX->start, ->old_root.level set
   to the level of eb X and ->generation set to the generation of eb X;

5) Then tree_mod_log_insert_root() calls tree_mod_log_free_eb() with
   tm_list as argument. After that, tree_mod_log_free_eb() calls
   __tree_mod_log_insert() for each member of tm_list in reverse order,
   from highest slot in eb X, slot N - 1, to slot 0 of eb X;

6) __tree_mod_log_insert() sets the sequence number of each given tree mod
   log operation - it increments fs_info->tree_mod_seq and sets
   fs_info->tree_mod_seq as the sequence number of the given tree mod log
   operation.

   This means that for the tm_list created at tree_mod_log_insert_root(),
   the element corresponding to slot 0 of eb X has the highest sequence
   number (1 + N), and the element corresponding to the last slot has the
   lowest sequence number (2);

7) Then, after inserting tm_list's elements into the tree mod log rbtree,
   the MOD_LOG_ROOT_REPLACE element is inserted, which gets the highest
   sequence number, which is N + 2;

8) Back to ctree.c:balance_level(), we free eb X by calling
   btrfs_free_tree_block() on it. Because eb X was created in the current
   transaction, has no other references and writeback did not happen for
   it, we add it back to the free space cache/tree;

9) Later some other task T allocates the metadata extent from eb X, since
   it is marked as free space in the space cache/tree, and uses it as a
   node for some other btree;

10) The tree mod log user task calls btrfs_search_old_slot(), which calls
    get_old_root(), and finally that calls __tree_mod_log_oldest_root()
    with time_seq == 1 and eb_root == eb Y;

11) First iteration of the while loop finds the tree mod log element with
    sequence number N + 2, for the logical address of eb Y and of type
    MOD_LOG_ROOT_REPLACE;

12) Because the operation type is MOD_LOG_ROOT_REPLACE, we don't break out
    of the loop, and set root_logical to point to tm->old_root.logical
    which corresponds to the logical address of eb X;

13) On the next iteration of the while loop, the call to
    tree_mod_log_search_oldest() returns the smallest tree mod log element
    for the logical address of eb X, which has a sequence number of 2, an
    operation type of MOD_LOG_KEY_REMOVE_WHILE_FREEING and corresponds to
    the old slot N - 1 of eb X (eb X had N items in it before being freed);

14) We then break out of the while loop and return the tree mod log operation
    of type MOD_LOG_ROOT_REPLACE (eb Y), and not the one for slot N - 1 of
    eb X, to get_old_root();

15) At get_old_root(), we process the MOD_LOG_ROOT_REPLACE operation
    and set "logical" to the logical address of eb X, which was the old
    root. We then call tree_mod_log_search() passing it the logical
    address of eb X and time_seq == 1;

16) Then before calling tree_mod_log_search(), task T adds a key to eb X,
    which results in adding a tree mod log operation of type
    MOD_LOG_KEY_ADD to the tree mod log - this is done at
    ctree.c:insert_ptr() - but after adding the tree mod log operation
    and before updating the number of items in eb X from 0 to 1...

17) The task at get_old_root() calls tree_mod_log_search() and gets the
    tree mod log operation of type MOD_LOG_KEY_ADD just added by task T.
    Then it enters the following if branch:

    if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
       (...)
    } (...)

    Calls read_tree_block() for eb X, which gets a reference on eb X but
    does not lock it - task T has it locked.
    Then it clones eb X while it has nritems set to 0 in its header, before
    task T sets nritems to 1 in eb X's header. From hereupon we use the
    clone of eb X which no other task has access to;

18) Then we call __tree_mod_log_rewind(), passing it the MOD_LOG_KEY_ADD
    mod log operation we just got from tree_mod_log_search() in the
    previous step and the cloned version of eb X;

19) At __tree_mod_log_rewind(), we set the local variable "n" to the number
    of items set in eb X's clone, which is 0. Then we enter the while loop,
    and in its first iteration we process the MOD_LOG_KEY_ADD operation,
    which just decrements "n" from 0 to (u32)-1, since "n" is declared with
    a type of u32. At the end of this iteration we call rb_next() to find the
    next tree mod log operation for eb X, that gives us the mod log operation
    of type MOD_LOG_KEY_REMOVE_WHILE_FREEING, for slot 0, with a sequence
    number of N + 1 (steps 3 to 6);

20) Then we go back to the top of the while loop and trigger the following
    BUG_ON():

        (...)
        switch (tm->op) {
        case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
                 BUG_ON(tm->slot < n);
                 fallthrough;
        (...)

    Because "n" has a value of (u32)-1 (4294967295) and tm->slot is 0.

Fix this by taking a read lock on the extent buffer before cloning it at
ctree.c:get_old_root(). This should be done regardless of the extent
buffer having been freed and reused, as a concurrent task might be
modifying it (while holding a write lock on it).

Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Link: https://lore.kernel.org/linux-btrfs/20210227155037.GN28049@hungrycats.org/
Fixes: 834328a849 ("Btrfs: tree mod log's old roots could still be part of the tree")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-25 09:04:06 +01:00
Nikolay Borisov
bf6dd437c3 btrfs: don't flush from btrfs_delayed_inode_reserve_metadata
commit 4d14c5cde5c268a2bc26addecf09489cb953ef64 upstream

Calling btrfs_qgroup_reserve_meta_prealloc from
btrfs_delayed_inode_reserve_metadata can result in flushing delalloc
while holding a transaction and delayed node locks. This is deadlock
prone. In the past multiple commits:

 * ae5e070eaca9 ("btrfs: qgroup: don't try to wait flushing if we're
already holding a transaction")

 * 6f23277a49 ("btrfs: qgroup: don't commit transaction when we already
 hold the handle")

Tried to solve various aspects of this but this was always a
whack-a-mole game. Unfortunately those 2 fixes don't solve a deadlock
scenario involving btrfs_delayed_node::mutex. Namely, one thread
can call btrfs_dirty_inode as a result of reading a file and modifying
its atime:

  PID: 6963   TASK: ffff8c7f3f94c000  CPU: 2   COMMAND: "test"
  #0  __schedule at ffffffffa529e07d
  #1  schedule at ffffffffa529e4ff
  #2  schedule_timeout at ffffffffa52a1bdd
  #3  wait_for_completion at ffffffffa529eeea             <-- sleeps with delayed node mutex held
  #4  start_delalloc_inodes at ffffffffc0380db5
  #5  btrfs_start_delalloc_snapshot at ffffffffc0393836
  #6  try_flush_qgroup at ffffffffc03f04b2
  #7  __btrfs_qgroup_reserve_meta at ffffffffc03f5bb6     <-- tries to reserve space and starts delalloc inodes.
  #8  btrfs_delayed_update_inode at ffffffffc03e31aa      <-- acquires delayed node mutex
  #9  btrfs_update_inode at ffffffffc0385ba8
 #10  btrfs_dirty_inode at ffffffffc038627b               <-- TRANSACTIION OPENED
 #11  touch_atime at ffffffffa4cf0000
 #12  generic_file_read_iter at ffffffffa4c1f123
 #13  new_sync_read at ffffffffa4ccdc8a
 #14  vfs_read at ffffffffa4cd0849
 #15  ksys_read at ffffffffa4cd0bd1
 #16  do_syscall_64 at ffffffffa4a052eb
 #17  entry_SYSCALL_64_after_hwframe at ffffffffa540008c

This will cause an asynchronous work to flush the delalloc inodes to
happen which can try to acquire the same delayed_node mutex:

  PID: 455    TASK: ffff8c8085fa4000  CPU: 5   COMMAND: "kworker/u16:30"
  #0  __schedule at ffffffffa529e07d
  #1  schedule at ffffffffa529e4ff
  #2  schedule_preempt_disabled at ffffffffa529e80a
  #3  __mutex_lock at ffffffffa529fdcb                    <-- goes to sleep, never wakes up.
  #4  btrfs_delayed_update_inode at ffffffffc03e3143      <-- tries to acquire the mutex
  #5  btrfs_update_inode at ffffffffc0385ba8              <-- this is the same inode that pid 6963 is holding
  #6  cow_file_range_inline.constprop.78 at ffffffffc0386be7
  #7  cow_file_range at ffffffffc03879c1
  #8  btrfs_run_delalloc_range at ffffffffc038894c
  #9  writepage_delalloc at ffffffffc03a3c8f
 #10  __extent_writepage at ffffffffc03a4c01
 #11  extent_write_cache_pages at ffffffffc03a500b
 #12  extent_writepages at ffffffffc03a6de2
 #13  do_writepages at ffffffffa4c277eb
 #14  __filemap_fdatawrite_range at ffffffffa4c1e5bb
 #15  btrfs_run_delalloc_work at ffffffffc0380987         <-- starts running delayed nodes
 #16  normal_work_helper at ffffffffc03b706c
 #17  process_one_work at ffffffffa4aba4e4
 #18  worker_thread at ffffffffa4aba6fd
 #19  kthread at ffffffffa4ac0a3d
 #20  ret_from_fork at ffffffffa54001ff

To fully address those cases the complete fix is to never issue any
flushing while holding the transaction or the delayed node lock. This
patch achieves it by calling qgroup_reserve_meta directly which will
either succeed without flushing or will fail and return -EDQUOT. In the
latter case that return value is going to be propagated to
btrfs_dirty_inode which will fallback to start a new transaction. That's
fine as the majority of time we expect the inode will have
BTRFS_DELAYED_NODE_INODE_DIRTY flag set which will result in directly
copying the in-memory state.

Fixes: c53e965360 ("btrfs: qgroup: try to flush qgroup space when we get -EDQUOT")
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-11 14:17:22 +01:00
Nikolay Borisov
cf9317ceb5 btrfs: export and rename qgroup_reserve_meta
commit 80e9baed722c853056e0c5374f51524593cb1031 upstream

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-11 14:17:22 +01:00
Filipe Manana
ae971992e9 btrfs: fix warning when creating a directory with smack enabled
commit fd57a98d6f0c98fa295813087f13afb26c224e73 upstream.

When we have smack enabled, during the creation of a directory smack may
attempt to add a "smack transmute" xattr on the inode, which results in
the following warning and trace:

  WARNING: CPU: 3 PID: 2548 at fs/btrfs/transaction.c:537 start_transaction+0x489/0x4f0
  Modules linked in: nft_objref nf_conntrack_netbios_ns (...)
  CPU: 3 PID: 2548 Comm: mkdir Not tainted 5.9.0-rc2smack+ #81
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
  RIP: 0010:start_transaction+0x489/0x4f0
  Code: e9 be fc ff ff (...)
  RSP: 0018:ffffc90001887d10 EFLAGS: 00010202
  RAX: ffff88816f1e0000 RBX: 0000000000000201 RCX: 0000000000000003
  RDX: 0000000000000201 RSI: 0000000000000002 RDI: ffff888177849000
  RBP: ffff888177849000 R08: 0000000000000001 R09: 0000000000000004
  R10: ffffffff825e8f7a R11: 0000000000000003 R12: ffffffffffffffe2
  R13: 0000000000000000 R14: ffff88803d884270 R15: ffff8881680d8000
  FS:  00007f67317b8440(0000) GS:ffff88817bcc0000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f67247a22a8 CR3: 000000004bfbc002 CR4: 0000000000370ee0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   ? slab_free_freelist_hook+0xea/0x1b0
   ? trace_hardirqs_on+0x1c/0xe0
   btrfs_setxattr_trans+0x3c/0xf0
   __vfs_setxattr+0x63/0x80
   smack_d_instantiate+0x2d3/0x360
   security_d_instantiate+0x29/0x40
   d_instantiate_new+0x38/0x90
   btrfs_mkdir+0x1cf/0x1e0
   vfs_mkdir+0x14f/0x200
   do_mkdirat+0x6d/0x110
   do_syscall_64+0x2d/0x40
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f673196ae6b
  Code: 8b 05 11 (...)
  RSP: 002b:00007ffc3c679b18 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
  RAX: ffffffffffffffda RBX: 00000000000001ff RCX: 00007f673196ae6b
  RDX: 0000000000000000 RSI: 00000000000001ff RDI: 00007ffc3c67a30d
  RBP: 00007ffc3c67a30d R08: 00000000000001ff R09: 0000000000000000
  R10: 000055d3e39fe930 R11: 0000000000000246 R12: 0000000000000000
  R13: 00007ffc3c679cd8 R14: 00007ffc3c67a30d R15: 00007ffc3c679ce0
  irq event stamp: 11029
  hardirqs last  enabled at (11037): [<ffffffff81153fe6>] console_unlock+0x486/0x670
  hardirqs last disabled at (11044): [<ffffffff81153c01>] console_unlock+0xa1/0x670
  softirqs last  enabled at (8864): [<ffffffff81e0102f>] asm_call_on_stack+0xf/0x20
  softirqs last disabled at (8851): [<ffffffff81e0102f>] asm_call_on_stack+0xf/0x20

This happens because at btrfs_mkdir() we call d_instantiate_new() while
holding a transaction handle, which results in the following call chain:

  btrfs_mkdir()
     trans = btrfs_start_transaction(root, 5);

     d_instantiate_new()
        smack_d_instantiate()
            __vfs_setxattr()
                btrfs_setxattr_trans()
                   btrfs_start_transaction()
                      start_transaction()
                         WARN_ON()
                           --> a tansaction start has TRANS_EXTWRITERS
                               set in its type
                         h->orig_rsv = h->block_rsv
                         h->block_rsv = NULL

     btrfs_end_transaction(trans)

Besides the warning triggered at start_transaction, we set the handle's
block_rsv to NULL which may cause some surprises later on.

So fix this by making btrfs_setxattr_trans() not start a transaction when
we already have a handle on one, stored in current->journal_info, and use
that handle. We are good to use the handle because at btrfs_mkdir() we did
reserve space for the xattr and the inode item.

Reported-by: Casey Schaufler <casey@schaufler-ca.com>
CC: stable@vger.kernel.org # 5.4+
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Tested-by: Casey Schaufler <casey@schaufler-ca.com>
Link: https://lore.kernel.org/linux-btrfs/434d856f-bd7b-4889-a6ec-e81aaebfa735@schaufler-ca.com/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-09 11:11:12 +01:00
Nikolay Borisov
e6ba61aaff btrfs: unlock extents in btrfs_zero_range in case of quota reservation errors
commit 4f6a49de64fd1b1dba5229c02047376da7cf24fd upstream.

If btrfs_qgroup_reserve_data returns an error (i.e quota limit reached)
the handling logic directly goes to the 'out' label without first
unlocking the extent range between lockstart, lockend. This results in
deadlocks as other processes try to lock the same extent.

Fixes: a7f8b1c2ac ("btrfs: file: reserve qgroup space after the hole punch range is locked")
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-09 11:11:11 +01:00
Nikolay Borisov
37ffce9668 btrfs: free correct amount of space in btrfs_delayed_inode_reserve_metadata
commit 0f9c03d824f6f522d3bc43629635c9765546ebc5 upstream.

Following commit f218ea6c47 ("btrfs: delayed-inode: Remove wrong
qgroup meta reservation calls") this function now reserves num_bytes,
rather than the fixed amount of nodesize. As such this requires the
same amount to be freed in case of failure. Fix this by adjusting
the amount we are freeing.

Fixes: f218ea6c47 ("btrfs: delayed-inode: Remove wrong qgroup meta reservation calls")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-09 11:11:11 +01:00
Dan Carpenter
a64ad80223 btrfs: validate qgroup inherit for SNAP_CREATE_V2 ioctl
commit 5011c5a663b9c6d6aff3d394f11049b371199627 upstream.

The problem is we're copying "inherit" from user space but we don't
necessarily know that we're copying enough data for a 64 byte
struct.  Then the next problem is that 'inherit' has a variable size
array at the end, and we have to verify that array is the size we
expected.

Fixes: 6f72c7e20d ("Btrfs: add qgroup inheritance")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-09 11:11:11 +01:00
Nikolay Borisov
e82407d249 btrfs: fix race between extent freeing/allocation when using bitmaps
commit 3c17916510428dbccdf657de050c34e208347089 upstream.

During allocation the allocator will try to allocate an extent using
cluster policy. Once the current cluster is exhausted it will remove the
entry under btrfs_free_cluster::lock and subsequently acquire
btrfs_free_space_ctl::tree_lock to dispose of the already-deleted entry
and adjust btrfs_free_space_ctl::total_bitmap. This poses a problem
because there exists a race condition between removing the entry under
one lock and doing the necessary accounting holding a different lock
since extent freeing only uses the 2nd lock. This can result in the
following situation:

T1:                                    T2:
btrfs_alloc_from_cluster               insert_into_bitmap <holds tree_lock>
 if (entry->bytes == 0)                   if (block_group && !list_empty(&block_group->cluster_list)) {
    rb_erase(entry)

 spin_unlock(&cluster->lock);
   (total_bitmaps is still 4)           spin_lock(&cluster->lock);
                                         <doesn't find entry in cluster->root>
 spin_lock(&ctl->tree_lock);             <goes to new_bitmap label, adds
<blocked since T2 holds tree_lock>       <a new entry and calls add_new_bitmap>
					    recalculate_thresholds  <crashes,
                                              due to total_bitmaps
					      becoming 5 and triggering
					      an ASSERT>

To fix this ensure that once depleted, the cluster entry is deleted when
both cluster lock and tree locks are held in the allocator (T1), this
ensures that even if there is a race with a concurrent
insert_into_bitmap call it will correctly find the entry in the cluster
and add the new space to it.

CC: <stable@vger.kernel.org> # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-09 11:11:11 +01:00
Filipe Manana
1559d94fec btrfs: fix stale data exposure after cloning a hole with NO_HOLES enabled
commit 3660d0bcdb82807d434da9d2e57d88b37331182d upstream.

When using the NO_HOLES feature, if we clone a file range that spans only
a hole into a range that is at or beyond the current i_size of the
destination file, we end up not setting the full sync runtime flag on the
inode. As a result, if we then fsync the destination file and have a power
failure, after log replay we can end up exposing stale data instead of
having a hole for that range.

The conditions for this to happen are the following:

1) We have a file with a size of, for example, 1280K;

2) There is a written (non-prealloc) extent for the file range from 1024K
   to 1280K with a length of 256K;

3) This particular file extent layout is durably persisted, so that the
   existing superblock persisted on disk points to a subvolume root where
   the file has that exact file extent layout and state;

4) The file is truncated to a smaller size, to an offset lower than the
   start offset of its last extent, for example to 800K. The truncate sets
   the full sync runtime flag on the inode;

6) Fsync the file to log it and clear the full sync runtime flag;

7) Clone a region that covers only a hole (implicit hole due to NO_HOLES)
   into the file with a destination offset that starts at or beyond the
   256K file extent item we had - for example to offset 1024K;

8) Since the clone operation does not find extents in the source range,
   we end up in the if branch at the bottom of btrfs_clone() where we
   punch a hole for the file range starting at offset 1024K by calling
   btrfs_replace_file_extents(). There we end up not setting the full
   sync flag on the inode, because we don't know we are being called in
   a clone context (and not fallocate's punch hole operation), and
   neither do we create an extent map to represent a hole because the
   requested range is beyond eof;

9) A further fsync to the file will be a fast fsync, since the clone
   operation did not set the full sync flag, and therefore it relies on
   modified extent maps to correctly log the file layout. But since
   it does not find any extent map marking the range from 1024K (the
   previous eof) to the new eof, it does not log a file extent item
   for that range representing the hole;

10) After a power failure no hole for the range starting at 1024K is
   punched and we end up exposing stale data from the old 256K extent.

Turning this into exact steps:

  $ mkfs.btrfs -f -O no-holes /dev/sdi
  $ mount /dev/sdi /mnt

  # Create our test file with 3 extents of 256K and a 256K hole at offset
  # 256K. The file has a size of 1280K.
  $ xfs_io -f -s \
              -c "pwrite -S 0xab -b 256K 0 256K" \
              -c "pwrite -S 0xcd -b 256K 512K 256K" \
              -c "pwrite -S 0xef -b 256K 768K 256K" \
              -c "pwrite -S 0x73 -b 256K 1024K 256K" \
              /mnt/sdi/foobar

  # Make sure it's durably persisted. We want the last committed super
  # block to point to this particular file extent layout.
  sync

  # Now truncate our file to a smaller size, falling within a position of
  # the second extent. This sets the full sync runtime flag on the inode.
  # Then fsync the file to log it and clear the full sync flag from the
  # inode. The third extent is no longer part of the file and therefore
  # it is not logged.
  $ xfs_io -c "truncate 800K" -c "fsync" /mnt/foobar

  # Now do a clone operation that only clones the hole and sets back the
  # file size to match the size it had before the truncate operation
  # (1280K).
  $ xfs_io \
        -c "reflink /mnt/foobar 256K 1024K 256K" \
        -c "fsync" \
        /mnt/foobar

  # File data before power failure:
  $ od -A d -t x1 /mnt/foobar
  0000000 ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab
  *
  0262144 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  *
  0524288 cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd
  *
  0786432 ef ef ef ef ef ef ef ef ef ef ef ef ef ef ef ef
  *
  0819200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  *
  1310720

  <power fail>

  # Mount the fs again to replay the log tree.
  $ mount /dev/sdi /mnt

  # File data after power failure:
  $ od -A d -t x1 /mnt/foobar
  0000000 ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab
  *
  0262144 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  *
  0524288 cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd
  *
  0786432 ef ef ef ef ef ef ef ef ef ef ef ef ef ef ef ef
  *
  0819200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  *
  1048576 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73
  *
  1310720

The range from 1024K to 1280K should correspond to a hole but instead it
points to stale data, to the 256K extent that should not exist after the
truncate operation.

The issue does not exists when not using NO_HOLES, because for that case
we use file extent items to represent holes, these are found and copied
during the loop that iterates over extents at btrfs_clone(), and that
causes btrfs_replace_file_extents() to be called with a non-NULL
extent_info argument and therefore set the full sync runtime flag on the
inode.

So fix this by making the code that deals with a trailing hole during
cloning, at btrfs_clone(), to set the full sync flag on the inode, if the
range starts at or beyond the current i_size.

A test case for fstests will follow soon.

Backporting notes: for kernel 5.4 the change goes to ioctl.c into
btrfs_clone before the last call to btrfs_punch_hole_range.

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-09 11:11:11 +01:00
Filipe Manana
6fc9e5866c btrfs: fix race between swap file activation and snapshot creation
commit dd0734f2a866f9d619d4abf97c3d71bcdee40ea9 upstream.

When creating a snapshot we check if the current number of swap files, in
the root, is non-zero, and if it is, we error out and warn that we can not
create the snapshot because there are active swap files.

However this is racy because when a task started activation of a swap
file, another task might have started already snapshot creation and might
have seen the counter for the number of swap files as zero. This means
that after the swap file is activated we may end up with a snapshot of the
same root successfully created, and therefore when the first write to the
swap file happens it has to fall back into COW mode, which should never
happen for active swap files.

Basically what can happen is:

1) Task A starts snapshot creation and enters ioctl.c:create_snapshot().
   There it sees that root->nr_swapfiles has a value of 0 so it continues;

2) Task B enters btrfs_swap_activate(). It is not aware that another task
   started snapshot creation but it did not finish yet. It increments
   root->nr_swapfiles from 0 to 1;

3) Task B checks that the file meets all requirements to be an active
   swap file - it has NOCOW set, there are no snapshots for the inode's
   root at the moment, no file holes, no reflinked extents, etc;

4) Task B returns success and now the file is an active swap file;

5) Task A commits the transaction to create the snapshot and finishes.
   The swap file's extents are now shared between the original root and
   the snapshot;

6) A write into an extent of the swap file is attempted - there is a
   snapshot of the file's root, so we fall back to COW mode and therefore
   the physical location of the extent changes on disk.

So fix this by taking the snapshot lock during swap file activation before
locking the extent range, as that is the order in which we lock these
during buffered writes.

Fixes: ed46ff3d42 ("Btrfs: support swap files")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-09 11:11:11 +01:00
Filipe Manana
501fdd1cef btrfs: fix race between writes to swap files and scrub
commit 195a49eaf655eb914896c92cecd96bc863c9feb3 upstream.

When we active a swap file, at btrfs_swap_activate(), we acquire the
exclusive operation lock to prevent the physical location of the swap
file extents to be changed by operations such as balance and device
replace/resize/remove. We also call there can_nocow_extent() which,
among other things, checks if the block group of a swap file extent is
currently RO, and if it is we can not use the extent, since a write
into it would result in COWing the extent.

However we have no protection against a scrub operation running after we
activate the swap file, which can result in the swap file extents to be
COWed while the scrub is running and operating on the respective block
group, because scrub turns a block group into RO before it processes it
and then back again to RW mode after processing it. That means an attempt
to write into a swap file extent while scrub is processing the respective
block group, will result in COWing the extent, changing its physical
location on disk.

Fix this by making sure that block groups that have extents that are used
by active swap files can not be turned into RO mode, therefore making it
not possible for a scrub to turn them into RO mode. When a scrub finds a
block group that can not be turned to RO due to the existence of extents
used by swap files, it proceeds to the next block group and logs a warning
message that mentions the block group was skipped due to active swap
files - this is the same approach we currently use for balance.

Fixes: ed46ff3d42 ("Btrfs: support swap files")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-09 11:11:11 +01:00
Ira Weiny
b2a4876132 btrfs: fix raid6 qstripe kmap
commit d70cef0d46729808dc53f145372c02b145c92604 upstream.

When a qstripe is required an extra page is allocated and mapped.  There
were 3 problems:

1) There is no corresponding call of kunmap() for the qstripe page.
2) There is no reason to map the qstripe page more than once if the
   number of bits set in rbio->dbitmap is greater than one.
3) There is no reason to map the parity page and unmap it each time
   through the loop.

The page memory can continue to be reused with a single mapping on each
iteration by raid6_call.gen_syndrome() without remapping.  So map the
page for the duration of the loop.

Similarly, improve the algorithm by mapping the parity page just 1 time.

Fixes: 5a6ac9eacb ("Btrfs, raid56: support parity scrub on raid56")
CC: stable@vger.kernel.org # 4.4.x: c17af96554: btrfs: raid56: simplify tracking of Q stripe presence
CC: stable@vger.kernel.org # 4.4.x
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-09 11:11:10 +01:00
Josef Bacik
a01415e5e8 btrfs: avoid double put of block group when emptying cluster
commit 95c85fba1f64c3249c67f0078a29f8a125078189 upstream.

It's wrong calling btrfs_put_block_group in
__btrfs_return_cluster_to_free_space if the block group passed is
different than the block group the cluster represents. As this means the
cluster doesn't have a reference to the passed block group. This results
in double put and a use-after-free bug.

Fix this by simply bailing if the block group we passed in does not
match the block group on the cluster.

Fixes: fa9c0d795f ("Btrfs: rework allocation clustering")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-09 11:11:10 +01:00
Josef Bacik
5aa2717b6b btrfs: fix error handling in commit_fs_roots
[ Upstream commit 4f4317c13a40194940acf4a71670179c4faca2b5 ]

While doing error injection I would sometimes get a corrupt file system.
This is because I was injecting errors at btrfs_search_slot, but would
only do it one time per stack.  This uncovered a problem in
commit_fs_roots, where if we get an error we would just break.  However
we're in a nested loop, the first loop being a loop to find all the
dirty fs roots, and then subsequent root updates would succeed clearing
the error value.

This isn't likely to happen in real scenarios, however we could
potentially get a random ENOMEM once and then not again, and we'd end up
with a corrupted file system.  Fix this by moving the error checking
around a bit to the main loop, as this is the only place where something
will fail, and return the error as soon as it occurs.

With this patch my reproducer no longer corrupts the file system.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-03-07 12:34:13 +01:00
Filipe Manana
de3ea5be51 btrfs: fix extent buffer leak on failure to copy root
commit 72c9925f87c8b74f36f8e75a4cd93d964538d3ca upstream.

At btrfs_copy_root(), if the call to btrfs_inc_ref() fails we end up
returning without unlocking and releasing our reference on the extent
buffer named "cow" we previously allocated with btrfs_alloc_tree_block().

So fix that by unlocking the extent buffer and dropping our reference on
it before returning.

Fixes: be20aa9dba ("Btrfs: Add mount option to turn off data cow")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 11:38:30 +01:00
Josef Bacik
9a739917ef btrfs: account for new extents being deleted in total_bytes_pinned
commit 81e75ac74ecba929d1e922bf93f9fc467232e39f upstream.

My recent patch set "A variety of lock contention fixes", found here

https://lore.kernel.org/linux-btrfs/cover.1608319304.git.josef@toxicpanda.com/
(Tracked in https://github.com/btrfs/linux/issues/86)

that reduce lock contention on the extent root by running delayed refs
less often resulted in a regression in generic/371.  This test
fallocate()'s the fs until it's full, deletes all the files, and then
tries to fallocate() until full again.

Before these patches we would run all of the delayed refs during
flushing, and then would commit the transaction because we had plenty of
pinned space to recover in order to allocate.  However my patches made
it so we weren't running the delayed refs as aggressively, which meant
that we appeared to have less pinned space when we were deciding to
commit the transaction.

We use the space_info->total_bytes_pinned to approximate how much space
we have pinned.  It's approximate because if we remove a reference to an
extent we may free it, but there may be more references to it than we
know of at that point, but we account it as pinned at the creation time,
and then it's properly accounted when the delayed ref runs.

The way we account for pinned space is if the
delayed_ref_head->total_ref_mod is < 0, because that is clearly a
freeing option.  However there is another case, and that is where
->total_ref_mod == 0 && ->must_insert_reserved == 1.

When we allocate a new extent, we have ->total_ref_mod == 1 and we have
->must_insert_reserved == 1.  This is used to indicate that it is a
brand new extent and will need to have its extent entry added before we
modify any references on the delayed ref head.  But if we subsequently
remove that extent reference, our ->total_ref_mod will be 0, and that
space will be pinned and freed.  Accounting for this case properly
allows for generic/371 to pass with my delayed refs patches applied.

It's important to note that this problem exists without the referenced
patches, it just was uncovered by them.

CC: stable@vger.kernel.org # 5.10
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 11:38:30 +01:00
Josef Bacik
7ec1536e80 btrfs: handle space_info::total_bytes_pinned inside the delayed ref itself
commit 2187374f35fe9cadbddaa9fcf0c4121365d914e8 upstream.

Currently we pass things around to figure out if we maybe freeing data
based on the state of the delayed refs head.  This makes the accounting
sort of confusing and hard to follow, as it's distinctly separate from
the delayed ref heads stuff, but also depends on it entirely.

Fix this by explicitly adjusting the space_info->total_bytes_pinned in
the delayed refs code.  We now have two places where we modify this
counter, once where we create the delayed and destroy the delayed refs,
and once when we pin and unpin the extents.  This means there is a
slight overlap between delayed refs and the pin/unpin mechanisms, but
this is simply used by the ENOSPC infrastructure to determine if we need
to commit the transaction, so there's no adverse affect from this, we
might simply commit thinking it will give us enough space when it might
not.

CC: stable@vger.kernel.org # 5.10
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 11:38:30 +01:00
Josef Bacik
acaeedb193 btrfs: splice remaining dirty_bg's onto the transaction dirty bg list
commit 938fcbfb0cbcf532a1869efab58e6009446b1ced upstream.

While doing error injection testing with my relocation patches I hit the
following assert:

  assertion failed: list_empty(&block_group->dirty_list), in fs/btrfs/block-group.c:3356
  ------------[ cut here ]------------
  kernel BUG at fs/btrfs/ctree.h:3357!
  invalid opcode: 0000 [#1] SMP NOPTI
  CPU: 0 PID: 24351 Comm: umount Tainted: G        W         5.10.0-rc3+ #193
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
  RIP: 0010:assertfail.constprop.0+0x18/0x1a
  RSP: 0018:ffffa09b019c7e00 EFLAGS: 00010282
  RAX: 0000000000000056 RBX: ffff8f6492c18000 RCX: 0000000000000000
  RDX: ffff8f64fbc27c60 RSI: ffff8f64fbc19050 RDI: ffff8f64fbc19050
  RBP: ffff8f6483bbdc00 R08: 0000000000000000 R09: 0000000000000000
  R10: ffffa09b019c7c38 R11: ffffffff85d70928 R12: ffff8f6492c18100
  R13: ffff8f6492c18148 R14: ffff8f6483bbdd70 R15: dead000000000100
  FS:  00007fbfda4cdc40(0000) GS:ffff8f64fbc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007fbfda666fd0 CR3: 000000013cf66002 CR4: 0000000000370ef0
  Call Trace:
   btrfs_free_block_groups.cold+0x55/0x55
   close_ctree+0x2c5/0x306
   ? fsnotify_destroy_marks+0x14/0x100
   generic_shutdown_super+0x6c/0x100
   kill_anon_super+0x14/0x30
   btrfs_kill_super+0x12/0x20
   deactivate_locked_super+0x36/0xa0
   cleanup_mnt+0x12d/0x190
   task_work_run+0x5c/0xa0
   exit_to_user_mode_prepare+0x1b1/0x1d0
   syscall_exit_to_user_mode+0x54/0x280
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

This happened because I injected an error in btrfs_cow_block() while
running the dirty block groups.  When we run the dirty block groups, we
splice the list onto a local list to process.  However if an error
occurs, we only cleanup the transactions dirty block group list, not any
pending block groups we have on our locally spliced list.

In fact if we fail to allocate a path in this function we'll also fail
to clean up the splice list.

Fix this by splicing the list back onto the transaction dirty block
group list so that the block groups are cleaned up.  Then add a 'out'
label and have the error conditions jump to out so that the errors are
handled properly.  This also has the side-effect of fixing a problem
where we would clear 'ret' on error because we unconditionally ran
btrfs_run_delayed_refs().

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 11:38:30 +01:00
Josef Bacik
c717ca57a4 btrfs: fix reloc root leak with 0 ref reloc roots on recovery
commit c78a10aebb275c38d0cfccae129a803fe622e305 upstream.

When recovering a relocation, if we run into a reloc root that has 0
refs we simply add it to the reloc_control->reloc_roots list, and then
clean it up later.  The problem with this is __del_reloc_root() doesn't
do anything if the root isn't in the radix tree, which in this case it
won't be because we never call __add_reloc_root() on the reloc_root.

This exit condition simply isn't correct really.  During normal
operation we can remove ourselves from the rb tree and then we're meant
to clean up later at merge_reloc_roots() time, and this happens
correctly.  During recovery we're depending on free_reloc_roots() to
drop our references, but we're short-circuiting.

Fix this by continuing to check if we're on the list and dropping
ourselves from the reloc_control root list and dropping our reference
appropriately.  Change the corresponding BUG_ON() to an ASSERT() that
does the correct thing if we aren't in the rb tree.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 11:38:30 +01:00
Josef Bacik
4d3edf72d6 btrfs: abort the transaction if we fail to inc ref in btrfs_copy_root
commit 867ed321f90d06aaba84e2c91de51cd3038825ef upstream.

While testing my error handling patches, I added a error injection site
at btrfs_inc_extent_ref, to validate the error handling I added was
doing the correct thing.  However I hit a pretty ugly corruption while
doing this check, with the following error injection stack trace:

btrfs_inc_extent_ref
  btrfs_copy_root
    create_reloc_root
      btrfs_init_reloc_root
	btrfs_record_root_in_trans
	  btrfs_start_transaction
	    btrfs_update_inode
	      btrfs_update_time
		touch_atime
		  file_accessed
		    btrfs_file_mmap

This is because we do not catch the error from btrfs_inc_extent_ref,
which in practice would be ENOMEM, which means we lose the extent
references for a root that has already been allocated and inserted,
which is the problem.  Fix this by aborting the transaction if we fail
to do the reference modification.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 11:38:29 +01:00
Josef Bacik
a1a5cc2548 btrfs: add asserts for deleting backref cache nodes
commit eddda68d97732ce05ca145f8e85e8a447f65cdad upstream.

A weird KASAN problem that Zygo reported could have been easily caught
if we checked for basic things in our backref freeing code.  We have two
methods of freeing a backref node

- btrfs_backref_free_node: this just is kfree() essentially.
- btrfs_backref_drop_node: this actually unlinks the node and cleans up
  everything and then calls btrfs_backref_free_node().

We should mostly be using btrfs_backref_drop_node(), to make sure the
node is properly unlinked from the backref cache, and only use
btrfs_backref_free_node() when we know the node isn't actually linked to
the backref cache.  We made a mistake here and thus got the KASAN splat.

Make this style of issue easier to find by adding some ASSERT()'s to
btrfs_backref_free_node() and adjusting our deletion stuff to properly
init the list so we can rely on list_empty() checks working properly.

  BUG: KASAN: use-after-free in btrfs_backref_cleanup_node+0x18a/0x420
  Read of size 8 at addr ffff888112402950 by task btrfs/28836

  CPU: 0 PID: 28836 Comm: btrfs Tainted: G        W         5.10.0-e35f27394290-for-next+ #23
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
  Call Trace:
   dump_stack+0xbc/0xf9
   ? btrfs_backref_cleanup_node+0x18a/0x420
   print_address_description.constprop.8+0x21/0x210
   ? record_print_text.cold.34+0x11/0x11
   ? btrfs_backref_cleanup_node+0x18a/0x420
   ? btrfs_backref_cleanup_node+0x18a/0x420
   kasan_report.cold.10+0x20/0x37
   ? btrfs_backref_cleanup_node+0x18a/0x420
   __asan_load8+0x69/0x90
   btrfs_backref_cleanup_node+0x18a/0x420
   btrfs_backref_release_cache+0x83/0x1b0
   relocate_block_group+0x394/0x780
   ? merge_reloc_roots+0x4a0/0x4a0
   btrfs_relocate_block_group+0x26e/0x4c0
   btrfs_relocate_chunk+0x52/0x120
   btrfs_balance+0xe2e/0x1900
   ? check_flags.part.50+0x6c/0x1e0
   ? btrfs_relocate_chunk+0x120/0x120
   ? kmem_cache_alloc_trace+0xa06/0xcb0
   ? _copy_from_user+0x83/0xc0
   btrfs_ioctl_balance+0x3a7/0x460
   btrfs_ioctl+0x24c8/0x4360
   ? __kasan_check_read+0x11/0x20
   ? check_chain_key+0x1f4/0x2f0
   ? __asan_loadN+0xf/0x20
   ? btrfs_ioctl_get_supported_features+0x30/0x30
   ? kvm_sched_clock_read+0x18/0x30
   ? check_chain_key+0x1f4/0x2f0
   ? lock_downgrade+0x3f0/0x3f0
   ? handle_mm_fault+0xad6/0x2150
   ? do_vfs_ioctl+0xfc/0x9d0
   ? ioctl_file_clone+0xe0/0xe0
   ? check_flags.part.50+0x6c/0x1e0
   ? check_flags.part.50+0x6c/0x1e0
   ? check_flags+0x26/0x30
   ? lock_is_held_type+0xc3/0xf0
   ? syscall_enter_from_user_mode+0x1b/0x60
   ? do_syscall_64+0x13/0x80
   ? rcu_read_lock_sched_held+0xa1/0xd0
   ? __kasan_check_read+0x11/0x20
   ? __fget_light+0xae/0x110
   __x64_sys_ioctl+0xc3/0x100
   do_syscall_64+0x37/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f4c4bdfe427
  RSP: 002b:00007fff33ee6df8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
  RAX: ffffffffffffffda RBX: 00007fff33ee6e98 RCX: 00007f4c4bdfe427
  RDX: 00007fff33ee6e98 RSI: 00000000c4009420 RDI: 0000000000000003
  RBP: 0000000000000003 R08: 0000000000000003 R09: 0000000000000078
  R10: fffffffffffff59d R11: 0000000000000202 R12: 0000000000000001
  R13: 0000000000000000 R14: 00007fff33ee8a34 R15: 0000000000000001

  Allocated by task 28836:
   kasan_save_stack+0x21/0x50
   __kasan_kmalloc.constprop.18+0xbe/0xd0
   kasan_kmalloc+0x9/0x10
   kmem_cache_alloc_trace+0x410/0xcb0
   btrfs_backref_alloc_node+0x46/0xf0
   btrfs_backref_add_tree_node+0x60d/0x11d0
   build_backref_tree+0xc5/0x700
   relocate_tree_blocks+0x2be/0xb90
   relocate_block_group+0x2eb/0x780
   btrfs_relocate_block_group+0x26e/0x4c0
   btrfs_relocate_chunk+0x52/0x120
   btrfs_balance+0xe2e/0x1900
   btrfs_ioctl_balance+0x3a7/0x460
   btrfs_ioctl+0x24c8/0x4360
   __x64_sys_ioctl+0xc3/0x100
   do_syscall_64+0x37/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

  Freed by task 28836:
   kasan_save_stack+0x21/0x50
   kasan_set_track+0x20/0x30
   kasan_set_free_info+0x1f/0x30
   __kasan_slab_free+0xf3/0x140
   kasan_slab_free+0xe/0x10
   kfree+0xde/0x200
   btrfs_backref_error_cleanup+0x452/0x530
   build_backref_tree+0x1a5/0x700
   relocate_tree_blocks+0x2be/0xb90
   relocate_block_group+0x2eb/0x780
   btrfs_relocate_block_group+0x26e/0x4c0
   btrfs_relocate_chunk+0x52/0x120
   btrfs_balance+0xe2e/0x1900
   btrfs_ioctl_balance+0x3a7/0x460
   btrfs_ioctl+0x24c8/0x4360
   __x64_sys_ioctl+0xc3/0x100
   do_syscall_64+0x37/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

  The buggy address belongs to the object at ffff888112402900
   which belongs to the cache kmalloc-128 of size 128
  The buggy address is located 80 bytes inside of
   128-byte region [ffff888112402900, ffff888112402980)
  The buggy address belongs to the page:
  page:0000000028b1cd08 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888131c810c0 pfn:0x112402
  flags: 0x17ffe0000000200(slab)
  raw: 017ffe0000000200 ffffea000424f308 ffffea0007d572c8 ffff888100040440
  raw: ffff888131c810c0 ffff888112402000 0000000100000009 0000000000000000
  page dumped because: kasan: bad access detected

  Memory state around the buggy address:
   ffff888112402800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
   ffff888112402880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  >ffff888112402900: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                   ^
   ffff888112402980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
   ffff888112402a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

Link: https://lore.kernel.org/linux-btrfs/20201208194607.GI31381@hungrycats.org/
CC: stable@vger.kernel.org # 5.10+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 11:38:29 +01:00
Josef Bacik
52f93e5ee7 btrfs: do not warn if we can't find the reloc root when looking up backref
commit f78743fbdae1bb31bc9c9233c3590a5048782381 upstream.

The backref code is looking for a reloc_root that corresponds to the
given fs root.  However any number of things could have gone wrong while
initializing that reloc_root, like ENOMEM while trying to allocate the
root itself, or EIO while trying to write the root item.  This would
result in no corresponding reloc_root being in the reloc root cache, and
thus would return NULL when we do the find_reloc_root() call.

Because of this we do not want to WARN_ON().  This presumably was meant
to catch developer errors, cases where we messed up adding the reloc
root.  However we can easily hit this case with error injection, and
thus should not do a WARN_ON().

CC: stable@vger.kernel.org # 5.10+
Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 11:38:29 +01:00
Josef Bacik
02785bae77 btrfs: do not cleanup upper nodes in btrfs_backref_cleanup_node
commit 7e2a870a599d4699a626ec26430c7a1ab14a2a49 upstream.

Zygo reported the following panic when testing my error handling patches
for relocation:

  kernel BUG at fs/btrfs/backref.c:2545!
  invalid opcode: 0000 [#1] SMP KASAN PTI CPU: 3 PID: 8472 Comm: btrfs Tainted: G        W 14
  Hardware name: QEMU Standard PC (i440FX + PIIX,

  Call Trace:
   btrfs_backref_error_cleanup+0x4df/0x530
   build_backref_tree+0x1a5/0x700
   ? _raw_spin_unlock+0x22/0x30
   ? release_extent_buffer+0x225/0x280
   ? free_extent_buffer.part.52+0xd7/0x140
   relocate_tree_blocks+0x2a6/0xb60
   ? kasan_unpoison_shadow+0x35/0x50
   ? do_relocation+0xc10/0xc10
   ? kasan_kmalloc+0x9/0x10
   ? kmem_cache_alloc_trace+0x6a3/0xcb0
   ? free_extent_buffer.part.52+0xd7/0x140
   ? rb_insert_color+0x342/0x360
   ? add_tree_block.isra.36+0x236/0x2b0
   relocate_block_group+0x2eb/0x780
   ? merge_reloc_roots+0x470/0x470
   btrfs_relocate_block_group+0x26e/0x4c0
   btrfs_relocate_chunk+0x52/0x120
   btrfs_balance+0xe2e/0x18f0
   ? pvclock_clocksource_read+0xeb/0x190
   ? btrfs_relocate_chunk+0x120/0x120
   ? lock_contended+0x620/0x6e0
   ? do_raw_spin_lock+0x1e0/0x1e0
   ? do_raw_spin_unlock+0xa8/0x140
   btrfs_ioctl_balance+0x1f9/0x460
   btrfs_ioctl+0x24c8/0x4380
   ? __kasan_check_read+0x11/0x20
   ? check_chain_key+0x1f4/0x2f0
   ? __asan_loadN+0xf/0x20
   ? btrfs_ioctl_get_supported_features+0x30/0x30
   ? kvm_sched_clock_read+0x18/0x30
   ? check_chain_key+0x1f4/0x2f0
   ? lock_downgrade+0x3f0/0x3f0
   ? handle_mm_fault+0xad6/0x2150
   ? do_vfs_ioctl+0xfc/0x9d0
   ? ioctl_file_clone+0xe0/0xe0
   ? check_flags.part.50+0x6c/0x1e0
   ? check_flags.part.50+0x6c/0x1e0
   ? check_flags+0x26/0x30
   ? lock_is_held_type+0xc3/0xf0
   ? syscall_enter_from_user_mode+0x1b/0x60
   ? do_syscall_64+0x13/0x80
   ? rcu_read_lock_sched_held+0xa1/0xd0
   ? __kasan_check_read+0x11/0x20
   ? __fget_light+0xae/0x110
   __x64_sys_ioctl+0xc3/0x100
   do_syscall_64+0x37/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

This occurs because of this check

  if (RB_EMPTY_NODE(&upper->rb_node))
	  BUG_ON(!list_empty(&node->upper));

As we are dropping the backref node, if we discover that our upper node
in the edge we just cleaned up isn't linked into the cache that we are
now done with this node, thus the BUG_ON().

However this is an erroneous assumption, as we will look up all the
references for a node first, and then process the pending edges.  All of
the 'upper' nodes in our pending edges won't be in the cache's rb_tree
yet, because they haven't been processed.  We could very well have many
edges still left to cleanup on this node.

The fact is we simply do not need this check, we can just process all of
the edges only for this node, because below this check we do the
following

  if (list_empty(&upper->lower)) {
	  list_add_tail(&upper->lower, &cache->leaves);
	  upper->lowest = 1;
  }

If the upper node truly isn't used yet, then we add it to the
cache->leaves list to be cleaned up later.  If it is still used then the
last child node that has it linked into its node will add it to the
leaves list and then it will be cleaned up.

Fix this problem by dropping this logic altogether.  With this fix I no
longer see the panic when testing with error injection in the backref
code.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 11:38:29 +01:00
Qu Wenruo
6a402b937e btrfs: fix double accounting of ordered extent for subpage case in btrfs_invalidapge
[ Upstream commit 951c80f83d61bd4b21794c8aba829c3c1a45c2d0 ]

Commit dbfdb6d1b3 ("Btrfs: Search for all ordered extents that could
span across a page") make btrfs_invalidapage() to search all ordered
extents.

The offending code looks like this:

  again:
	  start = page_start;
	  ordered = btrfs_lookup_ordered_range(inode, start, page_end - start + 1);
	  if (ordred) {
		  end = min(page_end,
			    ordered->file_offset + ordered->num_bytes - 1);

		  /* Do the cleanup */

		  start = end + 1;
		  if (start < page_end)
			  goto again;
	  }

The behavior is indeed necessary for the incoming subpage support, but
when it iterates through all the ordered extents, it also resets the
search range @start.

This means, for the following cases, we can double account the ordered
extents, causing its bytes_left underflow:

	Page offset
	0		16K		32K
	|<--- OE 1  --->|<--- OE 2 ---->|

As the first iteration will find ordered extent (OE) 1, which doesn't
cover the full page, thus after cleanup code, we need to retry again.
But again label will reset start to page_start, and we got OE 1 again,
which causes double accounting on OE 1, and cause OE 1's byte_left to
underflow.

This problem can only happen for subpage case, as for regular sectorsize
== PAGE_SIZE case, we will always find a OE ends at or after page end,
thus no way to trigger the problem.

Move the again label after start = page_start.  There will be more
comprehensive rework to convert the open coded loop to a proper while
loop for subpage support.

Fixes: dbfdb6d1b3 ("Btrfs: Search for all ordered extents that could span across a page")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-03-04 11:37:48 +01:00
Zhihao Cheng
006ef266c2 btrfs: clarify error returns values in __load_free_space_cache
[ Upstream commit 3cc64e7ebfb0d7faaba2438334c43466955a96e8 ]

Return value in __load_free_space_cache is not properly set after
(unlikely) memory allocation failures and 0 is returned instead.
This is not a problem for the caller load_free_space_cache because only
value 1 is considered as 'cache loaded' but for clarity it's better
to set the errors accordingly.

Fixes: a67509c300 ("Btrfs: add a io_ctl struct and helpers for dealing with the space cache")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-03-04 11:37:47 +01:00
Filipe Manana
a6703c7115 btrfs: fix crash after non-aligned direct IO write with O_DSYNC
Whenever we attempt to do a non-aligned direct IO write with O_DSYNC, we
end up triggering an assertion and crashing. Example reproducer:

  $ cat test.sh
  #!/bin/bash

  DEV=/dev/sdj
  MNT=/mnt/sdj

  mkfs.btrfs -f $DEV > /dev/null
  mount $DEV $MNT

  # Do a direct IO write with O_DSYNC into a non-aligned range...
  xfs_io -f -d -s -c "pwrite -S 0xab -b 64K 1111 64K" $MNT/foobar

  umount $MNT

When running the reproducer an assertion fails and produces the following
trace:

  [ 2418.403134] assertion failed: !current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA, in fs/btrfs/space-info.c:1467
  [ 2418.403745] ------------[ cut here ]------------
  [ 2418.404306] kernel BUG at fs/btrfs/ctree.h:3286!
  [ 2418.404862] invalid opcode: 0000 [#2] PREEMPT SMP DEBUG_PAGEALLOC PTI
  [ 2418.405451] CPU: 1 PID: 64705 Comm: xfs_io Tainted: G      D           5.10.15-btrfs-next-87 #1
  [ 2418.406026] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
  [ 2418.407228] RIP: 0010:assertfail.constprop.0+0x18/0x26 [btrfs]
  [ 2418.407835] Code: e6 48 c7 (...)
  [ 2418.409078] RSP: 0018:ffffb06080d13c98 EFLAGS: 00010246
  [ 2418.409696] RAX: 000000000000006c RBX: ffff994c1debbf08 RCX: 0000000000000000
  [ 2418.410302] RDX: 0000000000000000 RSI: 0000000000000027 RDI: 00000000ffffffff
  [ 2418.410904] RBP: ffff994c21770000 R08: 0000000000000000 R09: 0000000000000000
  [ 2418.411504] R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000010000
  [ 2418.412111] R13: ffff994c22198400 R14: ffff994c21770000 R15: 0000000000000000
  [ 2418.412713] FS:  00007f54fd7aff00(0000) GS:ffff994d35200000(0000) knlGS:0000000000000000
  [ 2418.413326] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [ 2418.413933] CR2: 000056549596d000 CR3: 000000010b928003 CR4: 0000000000370ee0
  [ 2418.414528] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  [ 2418.415109] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  [ 2418.415669] Call Trace:
  [ 2418.416254]  btrfs_reserve_data_bytes.cold+0x22/0x22 [btrfs]
  [ 2418.416812]  btrfs_check_data_free_space+0x4c/0xa0 [btrfs]
  [ 2418.417380]  btrfs_buffered_write+0x1b0/0x7f0 [btrfs]
  [ 2418.418315]  btrfs_file_write_iter+0x2a9/0x770 [btrfs]
  [ 2418.418920]  new_sync_write+0x11f/0x1c0
  [ 2418.419430]  vfs_write+0x2bb/0x3b0
  [ 2418.419972]  __x64_sys_pwrite64+0x90/0xc0
  [ 2418.420486]  do_syscall_64+0x33/0x80
  [ 2418.420979]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  [ 2418.421486] RIP: 0033:0x7f54fda0b986
  [ 2418.421981] Code: 48 c7 c0 (...)
  [ 2418.423019] RSP: 002b:00007ffc40569c38 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
  [ 2418.423547] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f54fda0b986
  [ 2418.424075] RDX: 0000000000010000 RSI: 000056549595e000 RDI: 0000000000000003
  [ 2418.424596] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000400
  [ 2418.425119] R10: 0000000000000400 R11: 0000000000000246 R12: 00000000ffffffff
  [ 2418.425644] R13: 0000000000000400 R14: 0000000000010000 R15: 0000000000000000
  [ 2418.426148] Modules linked in: btrfs blake2b_generic (...)
  [ 2418.429540] ---[ end trace ef2aeb44dc0afa34 ]---

1) At btrfs_file_write_iter() we set current->journal_info to
   BTRFS_DIO_SYNC_STUB;

2) We then call __btrfs_direct_write(), which calls btrfs_direct_IO();

3) We can't do the direct IO write because it starts at a non-aligned
   offset (1111). So at btrfs_direct_IO() we return -EINVAL (coming from
   check_direct_IO() which does the alignment check), but we leave
   current->journal_info set to BTRFS_DIO_SYNC_STUB - we only clear it
   at btrfs_dio_iomap_begin(), because we assume we always get there;

4) Then at __btrfs_direct_write() we see that the attempt to do the
   direct IO write was not successful, 0 bytes written, so we fallback
   to a buffered write by calling btrfs_buffered_write();

5) There we call btrfs_check_data_free_space() which in turn calls
   btrfs_alloc_data_chunk_ondemand() and that calls
   btrfs_reserve_data_bytes() with flush == BTRFS_RESERVE_FLUSH_DATA;

6) Then at btrfs_reserve_data_bytes() we have current->journal_info set to
   BTRFS_DIO_SYNC_STUB, therefore not NULL, and flush has the value
   BTRFS_RESERVE_FLUSH_DATA, triggering the second assertion:

  int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes,
                               enum btrfs_reserve_flush_enum flush)
  {
      struct btrfs_space_info *data_sinfo = fs_info->data_sinfo;
      int ret;

      ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA ||
             flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE);
      ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA);
  (...)

So fix that by setting the journal to NULL whenever check_direct_IO()
returns a failure.

This bug only affects 5.10 kernels, and the regression was introduced in
5.10-rc1 by commit 0eb79294db ("btrfs: dio iomap DSYNC workaround").
The bug does not exist in 5.11 kernels due to commit ecfdc08b8cc65d
("btrfs: remove dio iomap DSYNC workaround"), which depends on a large
patchset that went into the merge window for 5.11. So this is a fix only
for 5.10.x stable kernels, as there are people hitting this bug.

Fixes: 0eb79294db ("btrfs: dio iomap DSYNC workaround")
CC: stable@vger.kernel.org # 5.10 (and only 5.10)
Acked-by: David Sterba <dsterba@suse.com>
Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1181605
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-23 15:53:25 +01:00
David Sterba
aa0fd921d2 btrfs: fix backport of 2175bf57dc in 5.10.13
There's a mistake in backport of upstream commit 2175bf57dc ("btrfs:
fix possible free space tree corruption with online conversion") as
5.10.13 commit 2175bf57dc.

The enum value BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED has been added to the
wrong enum set, colliding with value of BTRFS_FS_QUOTA_ENABLE. This
could cause problems during the tree conversion, where the quotas
wouldn't be set up properly but the related code executed anyway due to
the bit set.

Link: https://lore.kernel.org/linux-btrfs/20210219111741.95DD.409509F4@e16-tech.com
Reported-by: Wang Yugui <wangyugui@e16-tech.com>
CC: stable@vger.kernel.org # 5.10.13+
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-23 15:53:25 +01:00
Josef Bacik
2175bf57dc btrfs: fix possible free space tree corruption with online conversion
commit 2f96e40212d435b328459ba6b3956395eed8fa9f upstream.

While running btrfs/011 in a loop I would often ASSERT() while trying to
add a new free space entry that already existed, or get an EEXIST while
adding a new block to the extent tree, which is another indication of
double allocation.

This occurs because when we do the free space tree population, we create
the new root and then populate the tree and commit the transaction.
The problem is when you create a new root, the root node and commit root
node are the same.  During this initial transaction commit we will run
all of the delayed refs that were paused during the free space tree
generation, and thus begin to cache block groups.  While caching block
groups the caching thread will be reading from the main root for the
free space tree, so as we make allocations we'll be changing the free
space tree, which can cause us to add the same range twice which results
in either the ASSERT(ret != -EEXIST); in __btrfs_add_free_space, or in a
variety of different errors when running delayed refs because of a
double allocation.

Fix this by marking the fs_info as unsafe to load the free space tree,
and fall back on the old slow method.  We could be smarter than this,
for example caching the block group while we're populating the free
space tree, but since this is a serious problem I've opted for the
simplest solution.

CC: stable@vger.kernel.org # 4.9+
Fixes: a5ed918285 ("Btrfs: implement the free space B-tree")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-03 23:28:40 +01:00
Su Yue
f343bf1aaf btrfs: fix lockdep warning due to seqcount_mutex on 32bit arch
commit c41ec4529d3448df8998950d7bada757a1b321cf upstream.

This effectively reverts commit d5c8238849 ("btrfs: convert
data_seqcount to seqcount_mutex_t").

While running fstests on 32 bits test box, many tests failed because of
warnings in dmesg. One of those warnings (btrfs/003):

  [66.441317] WARNING: CPU: 6 PID: 9251 at include/linux/seqlock.h:279 btrfs_remove_chunk+0x58b/0x7b0 [btrfs]
  [66.441446] CPU: 6 PID: 9251 Comm: btrfs Tainted: G           O      5.11.0-rc4-custom+ #5
  [66.441449] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ArchLinux 1.14.0-1 04/01/2014
  [66.441451] EIP: btrfs_remove_chunk+0x58b/0x7b0 [btrfs]
  [66.441472] EAX: 00000000 EBX: 00000001 ECX: c576070c EDX: c6b15803
  [66.441475] ESI: 10000000 EDI: 00000000 EBP: c56fbcfc ESP: c56fbc70
  [66.441477] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010246
  [66.441481] CR0: 80050033 CR2: 05c8da20 CR3: 04b20000 CR4: 00350ed0
  [66.441485] Call Trace:
  [66.441510]  btrfs_relocate_chunk+0xb1/0x100 [btrfs]
  [66.441529]  ? btrfs_lookup_block_group+0x17/0x20 [btrfs]
  [66.441562]  btrfs_balance+0x8ed/0x13b0 [btrfs]
  [66.441586]  ? btrfs_ioctl_balance+0x333/0x3c0 [btrfs]
  [66.441619]  ? __this_cpu_preempt_check+0xf/0x11
  [66.441643]  btrfs_ioctl_balance+0x333/0x3c0 [btrfs]
  [66.441664]  ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
  [66.441683]  btrfs_ioctl+0x414/0x2ae0 [btrfs]
  [66.441700]  ? __lock_acquire+0x35f/0x2650
  [66.441717]  ? lockdep_hardirqs_on+0x87/0x120
  [66.441720]  ? lockdep_hardirqs_on_prepare+0xd0/0x1e0
  [66.441724]  ? call_rcu+0x2d3/0x530
  [66.441731]  ? __might_fault+0x41/0x90
  [66.441736]  ? kvm_sched_clock_read+0x15/0x50
  [66.441740]  ? sched_clock+0x8/0x10
  [66.441745]  ? sched_clock_cpu+0x13/0x180
  [66.441750]  ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
  [66.441750]  ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
  [66.441768]  __ia32_sys_ioctl+0x165/0x8a0
  [66.441773]  ? __this_cpu_preempt_check+0xf/0x11
  [66.441785]  ? __might_fault+0x89/0x90
  [66.441791]  __do_fast_syscall_32+0x54/0x80
  [66.441796]  do_fast_syscall_32+0x32/0x70
  [66.441801]  do_SYSENTER_32+0x15/0x20
  [66.441805]  entry_SYSENTER_32+0x9f/0xf2
  [66.441808] EIP: 0xab7b5549
  [66.441814] EAX: ffffffda EBX: 00000003 ECX: c4009420 EDX: bfa91f5c
  [66.441816] ESI: 00000003 EDI: 00000001 EBP: 00000000 ESP: bfa91e98
  [66.441818] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00000292
  [66.441833] irq event stamp: 42579
  [66.441835] hardirqs last  enabled at (42585): [<c60eb065>] console_unlock+0x495/0x590
  [66.441838] hardirqs last disabled at (42590): [<c60eafd5>] console_unlock+0x405/0x590
  [66.441840] softirqs last  enabled at (41698): [<c601b76c>] call_on_stack+0x1c/0x60
  [66.441843] softirqs last disabled at (41681): [<c601b76c>] call_on_stack+0x1c/0x60

  ========================================================================
  btrfs_remove_chunk+0x58b/0x7b0:
  __seqprop_mutex_assert at linux/./include/linux/seqlock.h:279
  (inlined by) btrfs_device_set_bytes_used at linux/fs/btrfs/volumes.h:212
  (inlined by) btrfs_remove_chunk at linux/fs/btrfs/volumes.c:2994
  ========================================================================

The warning is produced by lockdep_assert_held() in
__seqprop_mutex_assert() if CONFIG_LOCKDEP is enabled.
And "olumes.c:2994 is btrfs_device_set_bytes_used() with mutex lock
fs_info->chunk_mutex held already.

After adding some debug prints, the cause was found that many
__alloc_device() are called with NULL @fs_info (during scanning ioctl).
Inside the function, btrfs_device_data_ordered_init() is expanded to
seqcount_mutex_init().  In this scenario, its second
parameter info->chunk_mutex  is &NULL->chunk_mutex which equals
to offsetof(struct btrfs_fs_info, chunk_mutex) unexpectedly. Thus,
seqcount_mutex_init() is called in wrong way. And later
btrfs_device_get/set helpers trigger lockdep warnings.

The device and filesystem object lifetimes are different and we'd have
to synchronize initialization of the btrfs_device::data_seqcount with
the fs_info, possibly using some additional synchronization. It would
still not prevent concurrent access to the seqcount lock when it's used
for read and initialization.

Commit d5c8238849 ("btrfs: convert data_seqcount to seqcount_mutex_t")
does not mention a particular problem being fixed so revert should not
cause any harm and we'll get the lockdep warning fixed.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=210139
Reported-by: Erhard F <erhard_f@mailbox.org>
Fixes: d5c8238849 ("btrfs: convert data_seqcount to seqcount_mutex_t")
CC: stable@vger.kernel.org # 5.10
CC: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Su Yue <l@damenly.su>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-03 23:28:40 +01:00
Josef Bacik
dbba7a38b0 btrfs: print the actual offset in btrfs_root_name
[ Upstream commit 71008734d27f2276fcef23a5e546d358430f2d52 ]

We're supposed to print the root_key.offset in btrfs_root_name in the
case of a reloc root, not the objectid.  Fix this helper to take the key
so we have access to the offset when we need it.

Fixes: 457f1864b5 ("btrfs: pretty print leaked root name")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-27 11:55:06 +01:00
Filipe Manana
adc11110d1 btrfs: send: fix invalid clone operations when cloning from the same file and root
commit 518837e65068c385dddc0a87b3e577c8be7c13b1 upstream.

When an incremental send finds an extent that is shared, it checks which
file extent items in the range refer to that extent, and for those it
emits clone operations, while for others it emits regular write operations
to avoid corruption at the destination (as described and fixed by commit
d906d49fc5 ("Btrfs: send, fix file corruption due to incorrect cloning
operations")).

However when the root we are cloning from is the send root, we are cloning
from the inode currently being processed and the source file range has
several extent items that partially point to the desired extent, with an
offset smaller than the offset in the file extent item for the range we
want to clone into, it can cause the algorithm to issue a clone operation
that starts at the current eof of the file being processed in the receiver
side, in which case the receiver will fail, with EINVAL, when attempting
to execute the clone operation.

Example reproducer:

  $ cat test-send-clone.sh
  #!/bin/bash

  DEV=/dev/sdi
  MNT=/mnt/sdi

  mkfs.btrfs -f $DEV >/dev/null
  mount $DEV $MNT

  # Create our test file with a single and large extent (1M) and with
  # different content for different file ranges that will be reflinked
  # later.
  xfs_io -f \
         -c "pwrite -S 0xab 0 128K" \
         -c "pwrite -S 0xcd 128K 128K" \
         -c "pwrite -S 0xef 256K 256K" \
         -c "pwrite -S 0x1a 512K 512K" \
         $MNT/foobar

  btrfs subvolume snapshot -r $MNT $MNT/snap1
  btrfs send -f /tmp/snap1.send $MNT/snap1

  # Now do a series of changes to our file such that we end up with
  # different parts of the extent reflinked into different file offsets
  # and we overwrite a large part of the extent too, so no file extent
  # items refer to that part that was overwritten. This used to confuse
  # the algorithm used by the kernel to figure out which file ranges to
  # clone, making it attempt to clone from a source range starting at
  # the current eof of the file, resulting in the receiver to fail since
  # it is an invalid clone operation.
  #
  xfs_io -c "reflink $MNT/foobar 64K 1M 960K" \
         -c "reflink $MNT/foobar 0K 512K 256K" \
         -c "reflink $MNT/foobar 512K 128K 256K" \
         -c "pwrite -S 0x73 384K 640K" \
         $MNT/foobar

  btrfs subvolume snapshot -r $MNT $MNT/snap2
  btrfs send -f /tmp/snap2.send -p $MNT/snap1 $MNT/snap2

  echo -e "\nFile digest in the original filesystem:"
  md5sum $MNT/snap2/foobar

  # Now unmount the filesystem, create a new one, mount it and try to
  # apply both send streams to recreate both snapshots.
  umount $DEV

  mkfs.btrfs -f $DEV >/dev/null
  mount $DEV $MNT

  btrfs receive -f /tmp/snap1.send $MNT
  btrfs receive -f /tmp/snap2.send $MNT

  # Must match what we got in the original filesystem of course.
  echo -e "\nFile digest in the new filesystem:"
  md5sum $MNT/snap2/foobar

  umount $MNT

When running the reproducer, the incremental send operation fails due to
an invalid clone operation:

  $ ./test-send-clone.sh
  wrote 131072/131072 bytes at offset 0
  128 KiB, 32 ops; 0.0015 sec (80.906 MiB/sec and 20711.9741 ops/sec)
  wrote 131072/131072 bytes at offset 131072
  128 KiB, 32 ops; 0.0013 sec (90.514 MiB/sec and 23171.6148 ops/sec)
  wrote 262144/262144 bytes at offset 262144
  256 KiB, 64 ops; 0.0025 sec (98.270 MiB/sec and 25157.2327 ops/sec)
  wrote 524288/524288 bytes at offset 524288
  512 KiB, 128 ops; 0.0052 sec (95.730 MiB/sec and 24506.9883 ops/sec)
  Create a readonly snapshot of '/mnt/sdi' in '/mnt/sdi/snap1'
  At subvol /mnt/sdi/snap1
  linked 983040/983040 bytes at offset 1048576
  960 KiB, 1 ops; 0.0006 sec (1.419 GiB/sec and 1550.3876 ops/sec)
  linked 262144/262144 bytes at offset 524288
  256 KiB, 1 ops; 0.0020 sec (120.192 MiB/sec and 480.7692 ops/sec)
  linked 262144/262144 bytes at offset 131072
  256 KiB, 1 ops; 0.0018 sec (133.833 MiB/sec and 535.3319 ops/sec)
  wrote 655360/655360 bytes at offset 393216
  640 KiB, 160 ops; 0.0093 sec (66.781 MiB/sec and 17095.8436 ops/sec)
  Create a readonly snapshot of '/mnt/sdi' in '/mnt/sdi/snap2'
  At subvol /mnt/sdi/snap2

  File digest in the original filesystem:
  9c13c61cb0b9f5abf45344375cb04dfa  /mnt/sdi/snap2/foobar
  At subvol snap1
  At snapshot snap2
  ERROR: failed to clone extents to foobar: Invalid argument

  File digest in the new filesystem:
  132f0396da8f48d2e667196bff882cfc  /mnt/sdi/snap2/foobar

The clone operation is invalid because its source range starts at the
current eof of the file in the receiver, causing the receiver to get
an EINVAL error from the clone operation when attempting it.

For the example above, what happens is the following:

1) When processing the extent at file offset 1M, the algorithm checks that
   the extent is shared and can be (fully or partially) found at file
   offset 0.

   At this point the file has a size (and eof) of 1M at the receiver;

2) It finds that our extent item at file offset 1M has a data offset of
   64K and, since the file extent item at file offset 0 has a data offset
   of 0, it issues a clone operation, from the same file and root, that
   has a source range offset of 64K, destination offset of 1M and a length
   of 64K, since the extent item at file offset 0 refers only to the first
   128K of the shared extent.

   After this clone operation, the file size (and eof) at the receiver is
   increased from 1M to 1088K (1M + 64K);

3) Now there's still 896K (960K - 64K) of data left to clone or write, so
   it checks for the next file extent item, which starts at file offset
   128K. This file extent item has a data offset of 0 and a length of
   256K, so a clone operation with a source range offset of 256K, a
   destination offset of 1088K (1M + 64K) and length of 128K is issued.

   After this operation the file size (and eof) at the receiver increases
   from 1088K to 1216K (1088K + 128K);

4) Now there's still 768K (896K - 128K) of data left to clone or write, so
   it checks for the next file extent item, located at file offset 384K.
   This file extent item points to a different extent, not the one we want
   to clone, with a length of 640K. So we issue a write operation into the
   file range 1216K (1088K + 128K, end of the last clone operation), with
   a length of 640K and with a data matching the one we can find for that
   range in send root.

   After this operation, the file size (and eof) at the receiver increases
   from 1216K to 1856K (1216K + 640K);

5) Now there's still 128K (768K - 640K) of data left to clone or write, so
   we look into the file extent item, which is for file offset 1M and it
   points to the extent we want to clone, with a data offset of 64K and a
   length of 960K.

   However this matches the file offset we started with, the start of the
   range to clone into. So we can't for sure find any file extent item
   from here onwards with the rest of the data we want to clone, yet we
   proceed and since the file extent item points to the shared extent,
   with a data offset of 64K, we issue a clone operation with a source
   range starting at file offset 1856K, which matches the file extent
   item's offset, 1M, plus the amount of data cloned and written so far,
   which is 64K (step 2) + 128K (step 3) + 640K (step 4). This clone
   operation is invalid since the source range offset matches the current
   eof of the file in the receiver. We should have stopped looking for
   extents to clone at this point and instead fallback to write, which
   would simply the contain the data in the file range from 1856K to
   1856K + 128K.

So fix this by stopping the loop that looks for file ranges to clone at
clone_range() when we reach the current eof of the file being processed,
if we are cloning from the same file and using the send root as the clone
root. This ensures any data not yet cloned will be sent to the receiver
through a write operation.

A test case for fstests will follow soon.

Reported-by: Massimo B. <massimo.b@gmx.net>
Link: https://lore.kernel.org/linux-btrfs/6ae34776e85912960a253a8327068a892998e685.camel@gmx.net/
Fixes: 11f2069c11 ("Btrfs: send, allow clone operations within the same file")
CC: stable@vger.kernel.org # 5.5+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27 11:54:53 +01:00
Josef Bacik
018abb5089 btrfs: don't clear ret in btrfs_start_dirty_block_groups
commit 34d1eb0e599875064955a74712f08ff14c8e3d5f upstream.

If we fail to update a block group item in the loop we'll break, however
we'll do btrfs_run_delayed_refs and lose our error value in ret, and
thus not clean up properly.  Fix this by only running the delayed refs
if there was no failure.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27 11:54:53 +01:00
Josef Bacik
14e17e90bf btrfs: fix lockdep splat in btrfs_recover_relocation
commit fb286100974e7239af243bc2255a52f29442f9c8 upstream.

While testing the error paths of relocation I hit the following lockdep
splat:

  ======================================================
  WARNING: possible circular locking dependency detected
  5.10.0-rc6+ #217 Not tainted
  ------------------------------------------------------
  mount/779 is trying to acquire lock:
  ffffa0e676945418 (&fs_info->balance_mutex){+.+.}-{3:3}, at: btrfs_recover_balance+0x2f0/0x340

  but task is already holding lock:
  ffffa0e60ee31da8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x100

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

  -> #2 (btrfs-root-00){++++}-{3:3}:
	 down_read_nested+0x43/0x130
	 __btrfs_tree_read_lock+0x27/0x100
	 btrfs_read_lock_root_node+0x31/0x40
	 btrfs_search_slot+0x462/0x8f0
	 btrfs_update_root+0x55/0x2b0
	 btrfs_drop_snapshot+0x398/0x750
	 clean_dirty_subvols+0xdf/0x120
	 btrfs_recover_relocation+0x534/0x5a0
	 btrfs_start_pre_rw_mount+0xcb/0x170
	 open_ctree+0x151f/0x1726
	 btrfs_mount_root.cold+0x12/0xea
	 legacy_get_tree+0x30/0x50
	 vfs_get_tree+0x28/0xc0
	 vfs_kern_mount.part.0+0x71/0xb0
	 btrfs_mount+0x10d/0x380
	 legacy_get_tree+0x30/0x50
	 vfs_get_tree+0x28/0xc0
	 path_mount+0x433/0xc10
	 __x64_sys_mount+0xe3/0x120
	 do_syscall_64+0x33/0x40
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  -> #1 (sb_internal#2){.+.+}-{0:0}:
	 start_transaction+0x444/0x700
	 insert_balance_item.isra.0+0x37/0x320
	 btrfs_balance+0x354/0xf40
	 btrfs_ioctl_balance+0x2cf/0x380
	 __x64_sys_ioctl+0x83/0xb0
	 do_syscall_64+0x33/0x40
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  -> #0 (&fs_info->balance_mutex){+.+.}-{3:3}:
	 __lock_acquire+0x1120/0x1e10
	 lock_acquire+0x116/0x370
	 __mutex_lock+0x7e/0x7b0
	 btrfs_recover_balance+0x2f0/0x340
	 open_ctree+0x1095/0x1726
	 btrfs_mount_root.cold+0x12/0xea
	 legacy_get_tree+0x30/0x50
	 vfs_get_tree+0x28/0xc0
	 vfs_kern_mount.part.0+0x71/0xb0
	 btrfs_mount+0x10d/0x380
	 legacy_get_tree+0x30/0x50
	 vfs_get_tree+0x28/0xc0
	 path_mount+0x433/0xc10
	 __x64_sys_mount+0xe3/0x120
	 do_syscall_64+0x33/0x40
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  other info that might help us debug this:

  Chain exists of:
    &fs_info->balance_mutex --> sb_internal#2 --> btrfs-root-00

   Possible unsafe locking scenario:

	 CPU0                    CPU1
	 ----                    ----
    lock(btrfs-root-00);
				 lock(sb_internal#2);
				 lock(btrfs-root-00);
    lock(&fs_info->balance_mutex);

   *** DEADLOCK ***

  2 locks held by mount/779:
   #0: ffffa0e60dc040e0 (&type->s_umount_key#47/1){+.+.}-{3:3}, at: alloc_super+0xb5/0x380
   #1: ffffa0e60ee31da8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x100

  stack backtrace:
  CPU: 0 PID: 779 Comm: mount Not tainted 5.10.0-rc6+ #217
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
  Call Trace:
   dump_stack+0x8b/0xb0
   check_noncircular+0xcf/0xf0
   ? trace_call_bpf+0x139/0x260
   __lock_acquire+0x1120/0x1e10
   lock_acquire+0x116/0x370
   ? btrfs_recover_balance+0x2f0/0x340
   __mutex_lock+0x7e/0x7b0
   ? btrfs_recover_balance+0x2f0/0x340
   ? btrfs_recover_balance+0x2f0/0x340
   ? rcu_read_lock_sched_held+0x3f/0x80
   ? kmem_cache_alloc_trace+0x2c4/0x2f0
   ? btrfs_get_64+0x5e/0x100
   btrfs_recover_balance+0x2f0/0x340
   open_ctree+0x1095/0x1726
   btrfs_mount_root.cold+0x12/0xea
   ? rcu_read_lock_sched_held+0x3f/0x80
   legacy_get_tree+0x30/0x50
   vfs_get_tree+0x28/0xc0
   vfs_kern_mount.part.0+0x71/0xb0
   btrfs_mount+0x10d/0x380
   ? __kmalloc_track_caller+0x2f2/0x320
   legacy_get_tree+0x30/0x50
   vfs_get_tree+0x28/0xc0
   ? capable+0x3a/0x60
   path_mount+0x433/0xc10
   __x64_sys_mount+0xe3/0x120
   do_syscall_64+0x33/0x40
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

This is straightforward to fix, simply release the path before we setup
the balance_ctl.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27 11:54:53 +01:00
Josef Bacik
5169a289fc btrfs: do not double free backref nodes on error
commit 49ecc679ab48b40ca799bf94b327d5284eac9e46 upstream.

Zygo reported the following KASAN splat:

  BUG: KASAN: use-after-free in btrfs_backref_cleanup_node+0x18a/0x420
  Read of size 8 at addr ffff888112402950 by task btrfs/28836

  CPU: 0 PID: 28836 Comm: btrfs Tainted: G        W         5.10.0-e35f27394290-for-next+ #23
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
  Call Trace:
   dump_stack+0xbc/0xf9
   ? btrfs_backref_cleanup_node+0x18a/0x420
   print_address_description.constprop.8+0x21/0x210
   ? record_print_text.cold.34+0x11/0x11
   ? btrfs_backref_cleanup_node+0x18a/0x420
   ? btrfs_backref_cleanup_node+0x18a/0x420
   kasan_report.cold.10+0x20/0x37
   ? btrfs_backref_cleanup_node+0x18a/0x420
   __asan_load8+0x69/0x90
   btrfs_backref_cleanup_node+0x18a/0x420
   btrfs_backref_release_cache+0x83/0x1b0
   relocate_block_group+0x394/0x780
   ? merge_reloc_roots+0x4a0/0x4a0
   btrfs_relocate_block_group+0x26e/0x4c0
   btrfs_relocate_chunk+0x52/0x120
   btrfs_balance+0xe2e/0x1900
   ? check_flags.part.50+0x6c/0x1e0
   ? btrfs_relocate_chunk+0x120/0x120
   ? kmem_cache_alloc_trace+0xa06/0xcb0
   ? _copy_from_user+0x83/0xc0
   btrfs_ioctl_balance+0x3a7/0x460
   btrfs_ioctl+0x24c8/0x4360
   ? __kasan_check_read+0x11/0x20
   ? check_chain_key+0x1f4/0x2f0
   ? __asan_loadN+0xf/0x20
   ? btrfs_ioctl_get_supported_features+0x30/0x30
   ? kvm_sched_clock_read+0x18/0x30
   ? check_chain_key+0x1f4/0x2f0
   ? lock_downgrade+0x3f0/0x3f0
   ? handle_mm_fault+0xad6/0x2150
   ? do_vfs_ioctl+0xfc/0x9d0
   ? ioctl_file_clone+0xe0/0xe0
   ? check_flags.part.50+0x6c/0x1e0
   ? check_flags.part.50+0x6c/0x1e0
   ? check_flags+0x26/0x30
   ? lock_is_held_type+0xc3/0xf0
   ? syscall_enter_from_user_mode+0x1b/0x60
   ? do_syscall_64+0x13/0x80
   ? rcu_read_lock_sched_held+0xa1/0xd0
   ? __kasan_check_read+0x11/0x20
   ? __fget_light+0xae/0x110
   __x64_sys_ioctl+0xc3/0x100
   do_syscall_64+0x37/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f4c4bdfe427

  Allocated by task 28836:
   kasan_save_stack+0x21/0x50
   __kasan_kmalloc.constprop.18+0xbe/0xd0
   kasan_kmalloc+0x9/0x10
   kmem_cache_alloc_trace+0x410/0xcb0
   btrfs_backref_alloc_node+0x46/0xf0
   btrfs_backref_add_tree_node+0x60d/0x11d0
   build_backref_tree+0xc5/0x700
   relocate_tree_blocks+0x2be/0xb90
   relocate_block_group+0x2eb/0x780
   btrfs_relocate_block_group+0x26e/0x4c0
   btrfs_relocate_chunk+0x52/0x120
   btrfs_balance+0xe2e/0x1900
   btrfs_ioctl_balance+0x3a7/0x460
   btrfs_ioctl+0x24c8/0x4360
   __x64_sys_ioctl+0xc3/0x100
   do_syscall_64+0x37/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

  Freed by task 28836:
   kasan_save_stack+0x21/0x50
   kasan_set_track+0x20/0x30
   kasan_set_free_info+0x1f/0x30
   __kasan_slab_free+0xf3/0x140
   kasan_slab_free+0xe/0x10
   kfree+0xde/0x200
   btrfs_backref_error_cleanup+0x452/0x530
   build_backref_tree+0x1a5/0x700
   relocate_tree_blocks+0x2be/0xb90
   relocate_block_group+0x2eb/0x780
   btrfs_relocate_block_group+0x26e/0x4c0
   btrfs_relocate_chunk+0x52/0x120
   btrfs_balance+0xe2e/0x1900
   btrfs_ioctl_balance+0x3a7/0x460
   btrfs_ioctl+0x24c8/0x4360
   __x64_sys_ioctl+0xc3/0x100
   do_syscall_64+0x37/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

This occurred because we freed our backref node in
btrfs_backref_error_cleanup(), but then tried to free it again in
btrfs_backref_release_cache().  This is because
btrfs_backref_release_cache() will cycle through all of the
cache->leaves nodes and free them up.  However
btrfs_backref_error_cleanup() freed the backref node with
btrfs_backref_free_node(), which simply kfree()d the backref node
without unlinking it from the cache.  Change this to a
btrfs_backref_drop_node(), which does the appropriate cleanup and
removes the node from the cache->leaves list, so when we go to free the
remaining cache we don't trip over items we've already dropped.

Fixes: 75bfb9aff4 ("Btrfs: cleanup error handling in build_backref_tree")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27 11:54:52 +01:00
Josef Bacik
9e2fc8f10c btrfs: don't get an EINTR during drop_snapshot for reloc
commit 18d3bff411c8d46d40537483bdc0b61b33ce0371 upstream.

This was partially fixed by f3e3d9cc35 ("btrfs: avoid possible signal
interruption of btrfs_drop_snapshot() on relocation tree"), however it
missed a spot when we restart a trans handle because we need to end the
transaction.  The fix is the same, simply use btrfs_join_transaction()
instead of btrfs_start_transaction() when deleting reloc roots.

Fixes: f3e3d9cc35 ("btrfs: avoid possible signal interruption of btrfs_drop_snapshot() on relocation tree")
CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27 11:54:52 +01:00
Filipe Manana
29543864c8 btrfs: fix transaction leak and crash after RO remount caused by qgroup rescan
[ Upstream commit cb13eea3b49055bd78e6ddf39defd6340f7379fc ]

If we remount a filesystem in RO mode while the qgroup rescan worker is
running, we can end up having it still running after the remount is done,
and at unmount time we may end up with an open transaction that ends up
never getting committed. If that happens we end up with several memory
leaks and can crash when hardware acceleration is unavailable for crc32c.
Possibly it can lead to other nasty surprises too, due to use-after-free
issues.

The following steps explain how the problem happens.

1) We have a filesystem mounted in RW mode and the qgroup rescan worker is
   running;

2) We remount the filesystem in RO mode, and never stop/pause the rescan
   worker, so after the remount the rescan worker is still running. The
   important detail here is that the rescan task is still running after
   the remount operation committed any ongoing transaction through its
   call to btrfs_commit_super();

3) The rescan is still running, and after the remount completed, the
   rescan worker started a transaction, after it finished iterating all
   leaves of the extent tree, to update the qgroup status item in the
   quotas tree. It does not commit the transaction, it only releases its
   handle on the transaction;

4) A filesystem unmount operation starts shortly after;

5) The unmount task, at close_ctree(), stops the transaction kthread,
   which had not had a chance to commit the open transaction since it was
   sleeping and the commit interval (default of 30 seconds) has not yet
   elapsed since the last time it committed a transaction;

6) So after stopping the transaction kthread we still have the transaction
   used to update the qgroup status item open. At close_ctree(), when the
   filesystem is in RO mode and no transaction abort happened (or the
   filesystem is in error mode), we do not expect to have any transaction
   open, so we do not call btrfs_commit_super();

7) We then proceed to destroy the work queues, free the roots and block
   groups, etc. After that we drop the last reference on the btree inode
   by calling iput() on it. Since there are dirty pages for the btree
   inode, corresponding to the COWed extent buffer for the quotas btree,
   btree_write_cache_pages() is invoked to flush those dirty pages. This
   results in creating a bio and submitting it, which makes us end up at
   btrfs_submit_metadata_bio();

8) At btrfs_submit_metadata_bio() we end up at the if-then-else branch
   that calls btrfs_wq_submit_bio(), because check_async_write() returned
   a value of 1. This value of 1 is because we did not have hardware
   acceleration available for crc32c, so BTRFS_FS_CSUM_IMPL_FAST was not
   set in fs_info->flags;

9) Then at btrfs_wq_submit_bio() we call btrfs_queue_work() against the
   workqueue at fs_info->workers, which was already freed before by the
   call to btrfs_stop_all_workers() at close_ctree(). This results in an
   invalid memory access due to a use-after-free, leading to a crash.

When this happens, before the crash there are several warnings triggered,
since we have reserved metadata space in a block group, the delayed refs
reservation, etc:

  ------------[ cut here ]------------
  WARNING: CPU: 4 PID: 1729896 at fs/btrfs/block-group.c:125 btrfs_put_block_group+0x63/0xa0 [btrfs]
  Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
  CPU: 4 PID: 1729896 Comm: umount Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  RIP: 0010:btrfs_put_block_group+0x63/0xa0 [btrfs]
  Code: f0 01 00 00 48 39 c2 75 (...)
  RSP: 0018:ffffb270826bbdd8 EFLAGS: 00010206
  RAX: 0000000000000001 RBX: ffff947ed73e4000 RCX: ffff947ebc8b29c8
  RDX: 0000000000000001 RSI: ffffffffc0b150a0 RDI: ffff947ebc8b2800
  RBP: ffff947ebc8b2800 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000001 R12: ffff947ed73e4110
  R13: ffff947ed73e4160 R14: ffff947ebc8b2988 R15: dead000000000100
  FS:  00007f15edfea840(0000) GS:ffff9481ad600000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f37e2893320 CR3: 0000000138f68001 CR4: 00000000003706e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   btrfs_free_block_groups+0x17f/0x2f0 [btrfs]
   close_ctree+0x2ba/0x2fa [btrfs]
   generic_shutdown_super+0x6c/0x100
   kill_anon_super+0x14/0x30
   btrfs_kill_super+0x12/0x20 [btrfs]
   deactivate_locked_super+0x31/0x70
   cleanup_mnt+0x100/0x160
   task_work_run+0x68/0xb0
   exit_to_user_mode_prepare+0x1bb/0x1c0
   syscall_exit_to_user_mode+0x4b/0x260
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f15ee221ee7
  Code: ff 0b 00 f7 d8 64 89 01 48 (...)
  RSP: 002b:00007ffe9470f0f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
  RAX: 0000000000000000 RBX: 00007f15ee347264 RCX: 00007f15ee221ee7
  RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 000056169701d000
  RBP: 0000561697018a30 R08: 0000000000000000 R09: 00007f15ee2e2be0
  R10: 000056169701efe0 R11: 0000000000000246 R12: 0000000000000000
  R13: 000056169701d000 R14: 0000561697018b40 R15: 0000561697018c60
  irq event stamp: 0
  hardirqs last  enabled at (0): [<0000000000000000>] 0x0
  hardirqs last disabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last  enabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last disabled at (0): [<0000000000000000>] 0x0
  ---[ end trace dd74718fef1ed5c6 ]---
  ------------[ cut here ]------------
  WARNING: CPU: 2 PID: 1729896 at fs/btrfs/block-rsv.c:459 btrfs_release_global_block_rsv+0x70/0xc0 [btrfs]
  Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
  CPU: 2 PID: 1729896 Comm: umount Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  RIP: 0010:btrfs_release_global_block_rsv+0x70/0xc0 [btrfs]
  Code: 48 83 bb b0 03 00 00 00 (...)
  RSP: 0018:ffffb270826bbdd8 EFLAGS: 00010206
  RAX: 000000000033c000 RBX: ffff947ed73e4000 RCX: 0000000000000000
  RDX: 0000000000000001 RSI: ffffffffc0b0d8c1 RDI: 00000000ffffffff
  RBP: ffff947ebc8b7000 R08: 0000000000000001 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000001 R12: ffff947ed73e4110
  R13: ffff947ed73e5278 R14: dead000000000122 R15: dead000000000100
  FS:  00007f15edfea840(0000) GS:ffff9481aca00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000561a79f76e20 CR3: 0000000138f68006 CR4: 00000000003706e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   btrfs_free_block_groups+0x24c/0x2f0 [btrfs]
   close_ctree+0x2ba/0x2fa [btrfs]
   generic_shutdown_super+0x6c/0x100
   kill_anon_super+0x14/0x30
   btrfs_kill_super+0x12/0x20 [btrfs]
   deactivate_locked_super+0x31/0x70
   cleanup_mnt+0x100/0x160
   task_work_run+0x68/0xb0
   exit_to_user_mode_prepare+0x1bb/0x1c0
   syscall_exit_to_user_mode+0x4b/0x260
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f15ee221ee7
  Code: ff 0b 00 f7 d8 64 89 01 (...)
  RSP: 002b:00007ffe9470f0f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
  RAX: 0000000000000000 RBX: 00007f15ee347264 RCX: 00007f15ee221ee7
  RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 000056169701d000
  RBP: 0000561697018a30 R08: 0000000000000000 R09: 00007f15ee2e2be0
  R10: 000056169701efe0 R11: 0000000000000246 R12: 0000000000000000
  R13: 000056169701d000 R14: 0000561697018b40 R15: 0000561697018c60
  irq event stamp: 0
  hardirqs last  enabled at (0): [<0000000000000000>] 0x0
  hardirqs last disabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last  enabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last disabled at (0): [<0000000000000000>] 0x0
  ---[ end trace dd74718fef1ed5c7 ]---
  ------------[ cut here ]------------
  WARNING: CPU: 2 PID: 1729896 at fs/btrfs/block-group.c:3377 btrfs_free_block_groups+0x25d/0x2f0 [btrfs]
  Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
  CPU: 5 PID: 1729896 Comm: umount Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  RIP: 0010:btrfs_free_block_groups+0x25d/0x2f0 [btrfs]
  Code: ad de 49 be 22 01 00 (...)
  RSP: 0018:ffffb270826bbde8 EFLAGS: 00010206
  RAX: ffff947ebeae1d08 RBX: ffff947ed73e4000 RCX: 0000000000000000
  RDX: 0000000000000001 RSI: ffff947e9d823ae8 RDI: 0000000000000246
  RBP: ffff947ebeae1d08 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000001 R12: ffff947ebeae1c00
  R13: ffff947ed73e5278 R14: dead000000000122 R15: dead000000000100
  FS:  00007f15edfea840(0000) GS:ffff9481ad200000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f1475d98ea8 CR3: 0000000138f68005 CR4: 00000000003706e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   close_ctree+0x2ba/0x2fa [btrfs]
   generic_shutdown_super+0x6c/0x100
   kill_anon_super+0x14/0x30
   btrfs_kill_super+0x12/0x20 [btrfs]
   deactivate_locked_super+0x31/0x70
   cleanup_mnt+0x100/0x160
   task_work_run+0x68/0xb0
   exit_to_user_mode_prepare+0x1bb/0x1c0
   syscall_exit_to_user_mode+0x4b/0x260
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f15ee221ee7
  Code: ff 0b 00 f7 d8 64 89 (...)
  RSP: 002b:00007ffe9470f0f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
  RAX: 0000000000000000 RBX: 00007f15ee347264 RCX: 00007f15ee221ee7
  RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 000056169701d000
  RBP: 0000561697018a30 R08: 0000000000000000 R09: 00007f15ee2e2be0
  R10: 000056169701efe0 R11: 0000000000000246 R12: 0000000000000000
  R13: 000056169701d000 R14: 0000561697018b40 R15: 0000561697018c60
  irq event stamp: 0
  hardirqs last  enabled at (0): [<0000000000000000>] 0x0
  hardirqs last disabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last  enabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last disabled at (0): [<0000000000000000>] 0x0
  ---[ end trace dd74718fef1ed5c8 ]---
  BTRFS info (device sdc): space_info 4 has 268238848 free, is not full
  BTRFS info (device sdc): space_info total=268435456, used=114688, pinned=0, reserved=16384, may_use=0, readonly=65536
  BTRFS info (device sdc): global_block_rsv: size 0 reserved 0
  BTRFS info (device sdc): trans_block_rsv: size 0 reserved 0
  BTRFS info (device sdc): chunk_block_rsv: size 0 reserved 0
  BTRFS info (device sdc): delayed_block_rsv: size 0 reserved 0
  BTRFS info (device sdc): delayed_refs_rsv: size 524288 reserved 0

And the crash, which only happens when we do not have crc32c hardware
acceleration, produces the following trace immediately after those
warnings:

  stack segment: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
  CPU: 2 PID: 1749129 Comm: umount Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  RIP: 0010:btrfs_queue_work+0x36/0x190 [btrfs]
  Code: 54 55 53 48 89 f3 (...)
  RSP: 0018:ffffb27082443ae8 EFLAGS: 00010282
  RAX: 0000000000000004 RBX: ffff94810ee9ad90 RCX: 0000000000000000
  RDX: 0000000000000001 RSI: ffff94810ee9ad90 RDI: ffff947ed8ee75a0
  RBP: a56b6b6b6b6b6b6b R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000007 R11: 0000000000000001 R12: ffff947fa9b435a8
  R13: ffff94810ee9ad90 R14: 0000000000000000 R15: ffff947e93dc0000
  FS:  00007f3cfe974840(0000) GS:ffff9481ac600000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f1b42995a70 CR3: 0000000127638003 CR4: 00000000003706e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   btrfs_wq_submit_bio+0xb3/0xd0 [btrfs]
   btrfs_submit_metadata_bio+0x44/0xc0 [btrfs]
   submit_one_bio+0x61/0x70 [btrfs]
   btree_write_cache_pages+0x414/0x450 [btrfs]
   ? kobject_put+0x9a/0x1d0
   ? trace_hardirqs_on+0x1b/0xf0
   ? _raw_spin_unlock_irqrestore+0x3c/0x60
   ? free_debug_processing+0x1e1/0x2b0
   do_writepages+0x43/0xe0
   ? lock_acquired+0x199/0x490
   __writeback_single_inode+0x59/0x650
   writeback_single_inode+0xaf/0x120
   write_inode_now+0x94/0xd0
   iput+0x187/0x2b0
   close_ctree+0x2c6/0x2fa [btrfs]
   generic_shutdown_super+0x6c/0x100
   kill_anon_super+0x14/0x30
   btrfs_kill_super+0x12/0x20 [btrfs]
   deactivate_locked_super+0x31/0x70
   cleanup_mnt+0x100/0x160
   task_work_run+0x68/0xb0
   exit_to_user_mode_prepare+0x1bb/0x1c0
   syscall_exit_to_user_mode+0x4b/0x260
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f3cfebabee7
  Code: ff 0b 00 f7 d8 64 89 01 (...)
  RSP: 002b:00007ffc9c9a05f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
  RAX: 0000000000000000 RBX: 00007f3cfecd1264 RCX: 00007f3cfebabee7
  RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 0000562b6b478000
  RBP: 0000562b6b473a30 R08: 0000000000000000 R09: 00007f3cfec6cbe0
  R10: 0000562b6b479fe0 R11: 0000000000000246 R12: 0000000000000000
  R13: 0000562b6b478000 R14: 0000562b6b473b40 R15: 0000562b6b473c60
  Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
  ---[ end trace dd74718fef1ed5cc ]---

Finally when we remove the btrfs module (rmmod btrfs), there are several
warnings about objects that were allocated from our slabs but were never
freed, consequence of the transaction that was never committed and got
leaked:

  =============================================================================
  BUG btrfs_delayed_ref_head (Tainted: G    B   W        ): Objects remaining in btrfs_delayed_ref_head on __kmem_cache_shutdown()
  -----------------------------------------------------------------------------

  INFO: Slab 0x0000000094c2ae56 objects=24 used=2 fp=0x000000002bfa2521 flags=0x17fffc000010200
  CPU: 5 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   slab_err+0xb7/0xdc
   ? lock_acquired+0x199/0x490
   __kmem_cache_shutdown+0x1ac/0x3c0
   ? lock_release+0x20e/0x4c0
   kmem_cache_destroy+0x55/0x120
   btrfs_delayed_ref_exit+0x11/0x35 [btrfs]
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 f5 (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  INFO: Object 0x0000000050cbdd61 @offset=12104
  INFO: Allocated in btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs] age=1894 cpu=6 pid=1729873
	__slab_alloc.isra.0+0x109/0x1c0
	kmem_cache_alloc+0x7bb/0x830
	btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs]
	btrfs_free_tree_block+0x128/0x360 [btrfs]
	__btrfs_cow_block+0x489/0x5f0 [btrfs]
	btrfs_cow_block+0xf7/0x220 [btrfs]
	btrfs_search_slot+0x62a/0xc40 [btrfs]
	btrfs_del_orphan_item+0x65/0xd0 [btrfs]
	btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
	open_ctree+0x125a/0x18a0 [btrfs]
	btrfs_mount_root.cold+0x13/0xed [btrfs]
	legacy_get_tree+0x30/0x60
	vfs_get_tree+0x28/0xe0
	fc_mount+0xe/0x40
	vfs_kern_mount.part.0+0x71/0x90
	btrfs_mount+0x13b/0x3e0 [btrfs]
  INFO: Freed in __btrfs_run_delayed_refs+0x1117/0x1290 [btrfs] age=4292 cpu=2 pid=1729526
	kmem_cache_free+0x34c/0x3c0
	__btrfs_run_delayed_refs+0x1117/0x1290 [btrfs]
	btrfs_run_delayed_refs+0x81/0x210 [btrfs]
	commit_cowonly_roots+0xfb/0x300 [btrfs]
	btrfs_commit_transaction+0x367/0xc40 [btrfs]
	sync_filesystem+0x74/0x90
	generic_shutdown_super+0x22/0x100
	kill_anon_super+0x14/0x30
	btrfs_kill_super+0x12/0x20 [btrfs]
	deactivate_locked_super+0x31/0x70
	cleanup_mnt+0x100/0x160
	task_work_run+0x68/0xb0
	exit_to_user_mode_prepare+0x1bb/0x1c0
	syscall_exit_to_user_mode+0x4b/0x260
	entry_SYSCALL_64_after_hwframe+0x44/0xa9
  INFO: Object 0x0000000086e9b0ff @offset=12776
  INFO: Allocated in btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs] age=1900 cpu=6 pid=1729873
	__slab_alloc.isra.0+0x109/0x1c0
	kmem_cache_alloc+0x7bb/0x830
	btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs]
	btrfs_alloc_tree_block+0x2bf/0x360 [btrfs]
	alloc_tree_block_no_bg_flush+0x4f/0x60 [btrfs]
	__btrfs_cow_block+0x12d/0x5f0 [btrfs]
	btrfs_cow_block+0xf7/0x220 [btrfs]
	btrfs_search_slot+0x62a/0xc40 [btrfs]
	btrfs_del_orphan_item+0x65/0xd0 [btrfs]
	btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
	open_ctree+0x125a/0x18a0 [btrfs]
	btrfs_mount_root.cold+0x13/0xed [btrfs]
	legacy_get_tree+0x30/0x60
	vfs_get_tree+0x28/0xe0
	fc_mount+0xe/0x40
	vfs_kern_mount.part.0+0x71/0x90
  INFO: Freed in __btrfs_run_delayed_refs+0x1117/0x1290 [btrfs] age=3141 cpu=6 pid=1729803
	kmem_cache_free+0x34c/0x3c0
	__btrfs_run_delayed_refs+0x1117/0x1290 [btrfs]
	btrfs_run_delayed_refs+0x81/0x210 [btrfs]
	btrfs_write_dirty_block_groups+0x17d/0x3d0 [btrfs]
	commit_cowonly_roots+0x248/0x300 [btrfs]
	btrfs_commit_transaction+0x367/0xc40 [btrfs]
	close_ctree+0x113/0x2fa [btrfs]
	generic_shutdown_super+0x6c/0x100
	kill_anon_super+0x14/0x30
	btrfs_kill_super+0x12/0x20 [btrfs]
	deactivate_locked_super+0x31/0x70
	cleanup_mnt+0x100/0x160
	task_work_run+0x68/0xb0
	exit_to_user_mode_prepare+0x1bb/0x1c0
	syscall_exit_to_user_mode+0x4b/0x260
	entry_SYSCALL_64_after_hwframe+0x44/0xa9
  kmem_cache_destroy btrfs_delayed_ref_head: Slab cache still has objects
  CPU: 5 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   kmem_cache_destroy+0x119/0x120
   btrfs_delayed_ref_exit+0x11/0x35 [btrfs]
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 f5 0b (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  =============================================================================
  BUG btrfs_delayed_tree_ref (Tainted: G    B   W        ): Objects remaining in btrfs_delayed_tree_ref on __kmem_cache_shutdown()
  -----------------------------------------------------------------------------

  INFO: Slab 0x0000000011f78dc0 objects=37 used=2 fp=0x0000000032d55d91 flags=0x17fffc000010200
  CPU: 3 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   slab_err+0xb7/0xdc
   ? lock_acquired+0x199/0x490
   __kmem_cache_shutdown+0x1ac/0x3c0
   ? lock_release+0x20e/0x4c0
   kmem_cache_destroy+0x55/0x120
   btrfs_delayed_ref_exit+0x1d/0x35 [btrfs]
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 f5 (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  INFO: Object 0x000000001a340018 @offset=4408
  INFO: Allocated in btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs] age=1917 cpu=6 pid=1729873
	__slab_alloc.isra.0+0x109/0x1c0
	kmem_cache_alloc+0x7bb/0x830
	btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs]
	btrfs_free_tree_block+0x128/0x360 [btrfs]
	__btrfs_cow_block+0x489/0x5f0 [btrfs]
	btrfs_cow_block+0xf7/0x220 [btrfs]
	btrfs_search_slot+0x62a/0xc40 [btrfs]
	btrfs_del_orphan_item+0x65/0xd0 [btrfs]
	btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
	open_ctree+0x125a/0x18a0 [btrfs]
	btrfs_mount_root.cold+0x13/0xed [btrfs]
	legacy_get_tree+0x30/0x60
	vfs_get_tree+0x28/0xe0
	fc_mount+0xe/0x40
	vfs_kern_mount.part.0+0x71/0x90
	btrfs_mount+0x13b/0x3e0 [btrfs]
  INFO: Freed in __btrfs_run_delayed_refs+0x63d/0x1290 [btrfs] age=4167 cpu=4 pid=1729795
	kmem_cache_free+0x34c/0x3c0
	__btrfs_run_delayed_refs+0x63d/0x1290 [btrfs]
	btrfs_run_delayed_refs+0x81/0x210 [btrfs]
	btrfs_commit_transaction+0x60/0xc40 [btrfs]
	create_subvol+0x56a/0x990 [btrfs]
	btrfs_mksubvol+0x3fb/0x4a0 [btrfs]
	__btrfs_ioctl_snap_create+0x119/0x1a0 [btrfs]
	btrfs_ioctl_snap_create+0x58/0x80 [btrfs]
	btrfs_ioctl+0x1a92/0x36f0 [btrfs]
	__x64_sys_ioctl+0x83/0xb0
	do_syscall_64+0x33/0x80
	entry_SYSCALL_64_after_hwframe+0x44/0xa9
  INFO: Object 0x000000002b46292a @offset=13648
  INFO: Allocated in btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs] age=1923 cpu=6 pid=1729873
	__slab_alloc.isra.0+0x109/0x1c0
	kmem_cache_alloc+0x7bb/0x830
	btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs]
	btrfs_alloc_tree_block+0x2bf/0x360 [btrfs]
	alloc_tree_block_no_bg_flush+0x4f/0x60 [btrfs]
	__btrfs_cow_block+0x12d/0x5f0 [btrfs]
	btrfs_cow_block+0xf7/0x220 [btrfs]
	btrfs_search_slot+0x62a/0xc40 [btrfs]
	btrfs_del_orphan_item+0x65/0xd0 [btrfs]
	btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
	open_ctree+0x125a/0x18a0 [btrfs]
	btrfs_mount_root.cold+0x13/0xed [btrfs]
	legacy_get_tree+0x30/0x60
	vfs_get_tree+0x28/0xe0
	fc_mount+0xe/0x40
	vfs_kern_mount.part.0+0x71/0x90
  INFO: Freed in __btrfs_run_delayed_refs+0x63d/0x1290 [btrfs] age=3164 cpu=6 pid=1729803
	kmem_cache_free+0x34c/0x3c0
	__btrfs_run_delayed_refs+0x63d/0x1290 [btrfs]
	btrfs_run_delayed_refs+0x81/0x210 [btrfs]
	commit_cowonly_roots+0xfb/0x300 [btrfs]
	btrfs_commit_transaction+0x367/0xc40 [btrfs]
	close_ctree+0x113/0x2fa [btrfs]
	generic_shutdown_super+0x6c/0x100
	kill_anon_super+0x14/0x30
	btrfs_kill_super+0x12/0x20 [btrfs]
	deactivate_locked_super+0x31/0x70
	cleanup_mnt+0x100/0x160
	task_work_run+0x68/0xb0
	exit_to_user_mode_prepare+0x1bb/0x1c0
	syscall_exit_to_user_mode+0x4b/0x260
	entry_SYSCALL_64_after_hwframe+0x44/0xa9
  kmem_cache_destroy btrfs_delayed_tree_ref: Slab cache still has objects
  CPU: 5 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   kmem_cache_destroy+0x119/0x120
   btrfs_delayed_ref_exit+0x1d/0x35 [btrfs]
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 f5 (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  =============================================================================
  BUG btrfs_delayed_extent_op (Tainted: G    B   W        ): Objects remaining in btrfs_delayed_extent_op on __kmem_cache_shutdown()
  -----------------------------------------------------------------------------

  INFO: Slab 0x00000000f145ce2f objects=22 used=1 fp=0x00000000af0f92cf flags=0x17fffc000010200
  CPU: 5 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   slab_err+0xb7/0xdc
   ? lock_acquired+0x199/0x490
   __kmem_cache_shutdown+0x1ac/0x3c0
   ? __mutex_unlock_slowpath+0x45/0x2a0
   kmem_cache_destroy+0x55/0x120
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 f5 (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  INFO: Object 0x000000004cf95ea8 @offset=6264
  INFO: Allocated in btrfs_alloc_tree_block+0x1e0/0x360 [btrfs] age=1931 cpu=6 pid=1729873
	__slab_alloc.isra.0+0x109/0x1c0
	kmem_cache_alloc+0x7bb/0x830
	btrfs_alloc_tree_block+0x1e0/0x360 [btrfs]
	alloc_tree_block_no_bg_flush+0x4f/0x60 [btrfs]
	__btrfs_cow_block+0x12d/0x5f0 [btrfs]
	btrfs_cow_block+0xf7/0x220 [btrfs]
	btrfs_search_slot+0x62a/0xc40 [btrfs]
	btrfs_del_orphan_item+0x65/0xd0 [btrfs]
	btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
	open_ctree+0x125a/0x18a0 [btrfs]
	btrfs_mount_root.cold+0x13/0xed [btrfs]
	legacy_get_tree+0x30/0x60
	vfs_get_tree+0x28/0xe0
	fc_mount+0xe/0x40
	vfs_kern_mount.part.0+0x71/0x90
	btrfs_mount+0x13b/0x3e0 [btrfs]
  INFO: Freed in __btrfs_run_delayed_refs+0xabd/0x1290 [btrfs] age=3173 cpu=6 pid=1729803
	kmem_cache_free+0x34c/0x3c0
	__btrfs_run_delayed_refs+0xabd/0x1290 [btrfs]
	btrfs_run_delayed_refs+0x81/0x210 [btrfs]
	commit_cowonly_roots+0xfb/0x300 [btrfs]
	btrfs_commit_transaction+0x367/0xc40 [btrfs]
	close_ctree+0x113/0x2fa [btrfs]
	generic_shutdown_super+0x6c/0x100
	kill_anon_super+0x14/0x30
	btrfs_kill_super+0x12/0x20 [btrfs]
	deactivate_locked_super+0x31/0x70
	cleanup_mnt+0x100/0x160
	task_work_run+0x68/0xb0
	exit_to_user_mode_prepare+0x1bb/0x1c0
	syscall_exit_to_user_mode+0x4b/0x260
	entry_SYSCALL_64_after_hwframe+0x44/0xa9
  kmem_cache_destroy btrfs_delayed_extent_op: Slab cache still has objects
  CPU: 3 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   kmem_cache_destroy+0x119/0x120
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  BTRFS: state leak: start 30408704 end 30425087 state 1 in tree 1 refs 1

Fix this issue by having the remount path stop the qgroup rescan worker
when we are remounting RO and teach the rescan worker to stop when a
remount is in progress. If later a remount in RW mode happens, we are
already resuming the qgroup rescan worker through the call to
btrfs_qgroup_rescan_resume(), so we do not need to worry about that.

Tested-by: Fabian Vogt <fvogt@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-19 18:27:24 +01:00
Pavel Begunkov
f89d84b35a btrfs: merge critical sections of discard lock in workfn
[ Upstream commit 8fc058597a283e9a37720abb0e8d68e342b9387d ]

btrfs_discard_workfn() drops discard_ctl->lock just to take it again in
a moment in btrfs_discard_schedule_work(). Avoid that and also reuse
ktime.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-19 18:27:24 +01:00
Pavel Begunkov
33061bd104 btrfs: fix async discard stall
[ Upstream commit ea9ed87c73e87e044b2c58d658eb4ba5216bc488 ]

Might happen that bg->discard_eligible_time was changed without
rescheduling, so btrfs_discard_workfn() wakes up earlier than that new
time, peek_discard_list() returns NULL, and all work halts and goes to
sleep without further rescheduling even there are block groups to
discard.

It happens pretty often, but not so visible from the userspace because
after some time it usually will be kicked off anyway by someone else
calling btrfs_discard_reschedule_work().

Fix it by continue rescheduling if block group discard lists are not
empty.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-19 18:27:24 +01:00
Su Yue
41b5ec745c btrfs: tree-checker: check if chunk item end overflows
[ Upstream commit 347fb0cfc9bab5195c6701e62eda488310d7938f ]

While mounting a crafted image provided by user, kernel panics due to
the invalid chunk item whose end is less than start.

  [66.387422] loop: module loaded
  [66.389773] loop0: detected capacity change from 262144 to 0
  [66.427708] BTRFS: device fsid a62e00e8-e94e-4200-8217-12444de93c2e devid 1 transid 12 /dev/loop0 scanned by mount (613)
  [66.431061] BTRFS info (device loop0): disk space caching is enabled
  [66.431078] BTRFS info (device loop0): has skinny extents
  [66.437101] BTRFS error: insert state: end < start 29360127 37748736
  [66.437136] ------------[ cut here ]------------
  [66.437140] WARNING: CPU: 16 PID: 613 at fs/btrfs/extent_io.c:557 insert_state.cold+0x1a/0x46 [btrfs]
  [66.437369] CPU: 16 PID: 613 Comm: mount Tainted: G           O      5.11.0-rc1-custom #45
  [66.437374] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ArchLinux 1.14.0-1 04/01/2014
  [66.437378] RIP: 0010:insert_state.cold+0x1a/0x46 [btrfs]
  [66.437420] RSP: 0018:ffff93e5414c3908 EFLAGS: 00010286
  [66.437427] RAX: 0000000000000000 RBX: 0000000001bfffff RCX: 0000000000000000
  [66.437431] RDX: 0000000000000000 RSI: ffffffffb90d4660 RDI: 00000000ffffffff
  [66.437434] RBP: ffff93e5414c3938 R08: 0000000000000001 R09: 0000000000000001
  [66.437438] R10: ffff93e5414c3658 R11: 0000000000000000 R12: ffff8ec782d72aa0
  [66.437441] R13: ffff8ec78bc71628 R14: 0000000000000000 R15: 0000000002400000
  [66.437447] FS:  00007f01386a8580(0000) GS:ffff8ec809000000(0000) knlGS:0000000000000000
  [66.437451] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [66.437455] CR2: 00007f01382fa000 CR3: 0000000109a34000 CR4: 0000000000750ee0
  [66.437460] PKRU: 55555554
  [66.437464] Call Trace:
  [66.437475]  set_extent_bit+0x652/0x740 [btrfs]
  [66.437539]  set_extent_bits_nowait+0x1d/0x20 [btrfs]
  [66.437576]  add_extent_mapping+0x1e0/0x2f0 [btrfs]
  [66.437621]  read_one_chunk+0x33c/0x420 [btrfs]
  [66.437674]  btrfs_read_chunk_tree+0x6a4/0x870 [btrfs]
  [66.437708]  ? kvm_sched_clock_read+0x18/0x40
  [66.437739]  open_ctree+0xb32/0x1734 [btrfs]
  [66.437781]  ? bdi_register_va+0x1b/0x20
  [66.437788]  ? super_setup_bdi_name+0x79/0xd0
  [66.437810]  btrfs_mount_root.cold+0x12/0xeb [btrfs]
  [66.437854]  ? __kmalloc_track_caller+0x217/0x3b0
  [66.437873]  legacy_get_tree+0x34/0x60
  [66.437880]  vfs_get_tree+0x2d/0xc0
  [66.437888]  vfs_kern_mount.part.0+0x78/0xc0
  [66.437897]  vfs_kern_mount+0x13/0x20
  [66.437902]  btrfs_mount+0x11f/0x3c0 [btrfs]
  [66.437940]  ? kfree+0x5ff/0x670
  [66.437944]  ? __kmalloc_track_caller+0x217/0x3b0
  [66.437962]  legacy_get_tree+0x34/0x60
  [66.437974]  vfs_get_tree+0x2d/0xc0
  [66.437983]  path_mount+0x48c/0xd30
  [66.437998]  __x64_sys_mount+0x108/0x140
  [66.438011]  do_syscall_64+0x38/0x50
  [66.438018]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  [66.438023] RIP: 0033:0x7f0138827f6e
  [66.438033] RSP: 002b:00007ffecd79edf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
  [66.438040] RAX: ffffffffffffffda RBX: 00007f013894c264 RCX: 00007f0138827f6e
  [66.438044] RDX: 00005593a4a41360 RSI: 00005593a4a33690 RDI: 00005593a4a3a6c0
  [66.438047] RBP: 00005593a4a33440 R08: 0000000000000000 R09: 0000000000000001
  [66.438050] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
  [66.438054] R13: 00005593a4a3a6c0 R14: 00005593a4a41360 R15: 00005593a4a33440
  [66.438078] irq event stamp: 18169
  [66.438082] hardirqs last  enabled at (18175): [<ffffffffb81154bf>] console_unlock+0x4ff/0x5f0
  [66.438088] hardirqs last disabled at (18180): [<ffffffffb8115427>] console_unlock+0x467/0x5f0
  [66.438092] softirqs last  enabled at (16910): [<ffffffffb8a00fe2>] asm_call_irq_on_stack+0x12/0x20
  [66.438097] softirqs last disabled at (16905): [<ffffffffb8a00fe2>] asm_call_irq_on_stack+0x12/0x20
  [66.438103] ---[ end trace e114b111db64298b ]---
  [66.438107] BTRFS error: found node 12582912 29360127 on insert of 37748736 29360127
  [66.438127] BTRFS critical: panic in extent_io_tree_panic:679: locking error: extent tree was modified by another thread while locked (errno=-17 Object already exists)
  [66.441069] ------------[ cut here ]------------
  [66.441072] kernel BUG at fs/btrfs/extent_io.c:679!
  [66.442064] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
  [66.443018] CPU: 16 PID: 613 Comm: mount Tainted: G        W  O      5.11.0-rc1-custom #45
  [66.444538] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ArchLinux 1.14.0-1 04/01/2014
  [66.446223] RIP: 0010:extent_io_tree_panic.isra.0+0x23/0x25 [btrfs]
  [66.450878] RSP: 0018:ffff93e5414c3948 EFLAGS: 00010246
  [66.451840] RAX: 0000000000000000 RBX: 0000000001bfffff RCX: 0000000000000000
  [66.453141] RDX: 0000000000000000 RSI: ffffffffb90d4660 RDI: 00000000ffffffff
  [66.454445] RBP: ffff93e5414c3948 R08: 0000000000000001 R09: 0000000000000001
  [66.455743] R10: ffff93e5414c3658 R11: 0000000000000000 R12: ffff8ec782d728c0
  [66.457055] R13: ffff8ec78bc71628 R14: ffff8ec782d72aa0 R15: 0000000002400000
  [66.458356] FS:  00007f01386a8580(0000) GS:ffff8ec809000000(0000) knlGS:0000000000000000
  [66.459841] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [66.460895] CR2: 00007f01382fa000 CR3: 0000000109a34000 CR4: 0000000000750ee0
  [66.462196] PKRU: 55555554
  [66.462692] Call Trace:
  [66.463139]  set_extent_bit.cold+0x30/0x98 [btrfs]
  [66.464049]  set_extent_bits_nowait+0x1d/0x20 [btrfs]
  [66.490466]  add_extent_mapping+0x1e0/0x2f0 [btrfs]
  [66.514097]  read_one_chunk+0x33c/0x420 [btrfs]
  [66.534976]  btrfs_read_chunk_tree+0x6a4/0x870 [btrfs]
  [66.555718]  ? kvm_sched_clock_read+0x18/0x40
  [66.575758]  open_ctree+0xb32/0x1734 [btrfs]
  [66.595272]  ? bdi_register_va+0x1b/0x20
  [66.614638]  ? super_setup_bdi_name+0x79/0xd0
  [66.633809]  btrfs_mount_root.cold+0x12/0xeb [btrfs]
  [66.652938]  ? __kmalloc_track_caller+0x217/0x3b0
  [66.671925]  legacy_get_tree+0x34/0x60
  [66.690300]  vfs_get_tree+0x2d/0xc0
  [66.708221]  vfs_kern_mount.part.0+0x78/0xc0
  [66.725808]  vfs_kern_mount+0x13/0x20
  [66.742730]  btrfs_mount+0x11f/0x3c0 [btrfs]
  [66.759350]  ? kfree+0x5ff/0x670
  [66.775441]  ? __kmalloc_track_caller+0x217/0x3b0
  [66.791750]  legacy_get_tree+0x34/0x60
  [66.807494]  vfs_get_tree+0x2d/0xc0
  [66.823349]  path_mount+0x48c/0xd30
  [66.838753]  __x64_sys_mount+0x108/0x140
  [66.854412]  do_syscall_64+0x38/0x50
  [66.869673]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  [66.885093] RIP: 0033:0x7f0138827f6e
  [66.945613] RSP: 002b:00007ffecd79edf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
  [66.977214] RAX: ffffffffffffffda RBX: 00007f013894c264 RCX: 00007f0138827f6e
  [66.994266] RDX: 00005593a4a41360 RSI: 00005593a4a33690 RDI: 00005593a4a3a6c0
  [67.011544] RBP: 00005593a4a33440 R08: 0000000000000000 R09: 0000000000000001
  [67.028836] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
  [67.045812] R13: 00005593a4a3a6c0 R14: 00005593a4a41360 R15: 00005593a4a33440
  [67.216138] ---[ end trace e114b111db64298c ]---
  [67.237089] RIP: 0010:extent_io_tree_panic.isra.0+0x23/0x25 [btrfs]
  [67.325317] RSP: 0018:ffff93e5414c3948 EFLAGS: 00010246
  [67.347946] RAX: 0000000000000000 RBX: 0000000001bfffff RCX: 0000000000000000
  [67.371343] RDX: 0000000000000000 RSI: ffffffffb90d4660 RDI: 00000000ffffffff
  [67.394757] RBP: ffff93e5414c3948 R08: 0000000000000001 R09: 0000000000000001
  [67.418409] R10: ffff93e5414c3658 R11: 0000000000000000 R12: ffff8ec782d728c0
  [67.441906] R13: ffff8ec78bc71628 R14: ffff8ec782d72aa0 R15: 0000000002400000
  [67.465436] FS:  00007f01386a8580(0000) GS:ffff8ec809000000(0000) knlGS:0000000000000000
  [67.511660] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [67.535047] CR2: 00007f01382fa000 CR3: 0000000109a34000 CR4: 0000000000750ee0
  [67.558449] PKRU: 55555554
  [67.581146] note: mount[613] exited with preempt_count 2

The image has a chunk item which has a logical start 37748736 and length
18446744073701163008 (-8M). The calculated end 29360127 overflows.
EEXIST was caught by insert_state() because of the duplicate end and
extent_io_tree_panic() was called.

Add overflow check of chunk item end to tree checker so it can be
detected early at mount time.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=208929
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Su Yue <l@damenly.su>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-19 18:27:22 +01:00
Su Yue
f37fba66a4 btrfs: prevent NULL pointer dereference in extent_io_tree_panic
commit 29b665cc51e8b602bf2a275734349494776e3dbc upstream.

Some extent io trees are initialized with NULL private member (e.g.
btrfs_device::alloc_state and btrfs_fs_info::excluded_extents).
Dereference of a NULL tree->private as inode pointer will cause panic.

Pass tree->fs_info as it's known to be valid in all cases.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=208929
Fixes: 05912a3c04 ("btrfs: drop extent_io_ops::tree_fs_info callback")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Su Yue <l@damenly.su>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-19 18:27:17 +01:00
Qu Wenruo
e883eb5d15 btrfs: reloc: fix wrong file extent type check to avoid false ENOENT
commit 50e31ef486afe60f128d42fb9620e2a63172c15c upstream.

[BUG]
There are several bug reports about recent kernel unable to relocate
certain data block groups.

Sometimes the error just goes away, but there is one reporter who can
reproduce it reliably.

The dmesg would look like:

  [438.260483] BTRFS info (device dm-10): balance: start -dvrange=34625344765952..34625344765953
  [438.269018] BTRFS info (device dm-10): relocating block group 34625344765952 flags data|raid1
  [450.439609] BTRFS info (device dm-10): found 167 extents, stage: move data extents
  [463.501781] BTRFS info (device dm-10): balance: ended with status: -2

[CAUSE]
The ENOENT error is returned from the following call chain:

  add_data_references()
  |- delete_v1_space_cache();
     |- if (!found)
	   return -ENOENT;

The variable @found is set to true if we find a data extent whose
disk bytenr matches parameter @data_bytes.

With extra debugging, the offending tree block looks like this:

  leaf bytenr = 42676709441536, data_bytenr = 34626327621632

                ctime 1567904822.739884119 (2019-09-08 03:07:02)
                mtime 0.0 (1970-01-01 01:00:00)
                otime 0.0 (1970-01-01 01:00:00)
        item 27 key (51933 EXTENT_DATA 0) itemoff 9854 itemsize 53
                generation 1517381 type 2 (prealloc)
                prealloc data disk byte 34626327621632 nr 262144 <<<
                prealloc data offset 0 nr 262144
        item 28 key (52262 ROOT_ITEM 0) itemoff 9415 itemsize 439
                generation 2618893 root_dirid 256 bytenr 42677048360960 level 3 refs 1
                lastsnap 2618893 byte_limit 0 bytes_used 5557338112 flags 0x0(none)
                uuid d0d4361f-d231-6d40-8901-fe506e4b2b53

Although item 27 has disk bytenr 34626327621632, which matches the
data_bytenr, its type is prealloc, not reg.
This makes the existing code skip that item, and return ENOENT.

[FIX]
The code is modified in commit 19b546d7a1 ("btrfs: relocation: Use
btrfs_find_all_leafs to locate data extent parent tree leaves"), before
that commit, we use something like

  "if (type == BTRFS_FILE_EXTENT_INLINE) continue;"

But in that offending commit, we use (type == BTRFS_FILE_EXTENT_REG),
ignoring BTRFS_FILE_EXTENT_PREALLOC.

Fix it by also checking BTRFS_FILE_EXTENT_PREALLOC.

Reported-by: Stéphane Lesimple <stephane_btrfs2@lesimple.fr>
Link: https://lore.kernel.org/linux-btrfs/505cabfa88575ed6dbe7cb922d8914fb@lesimple.fr
Fixes: 19b546d7a1 ("btrfs: relocation: Use btrfs_find_all_leafs to locate data extent parent tree leaves")
CC: stable@vger.kernel.org # 5.6+
Tested-By: Stéphane Lesimple <stephane_btrfs2@lesimple.fr>
Reviewed-by: Su Yue <l@damenly.su>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-19 18:27:17 +01:00
Josef Bacik
e3b5252b5c btrfs: shrink delalloc pages instead of full inodes
[ Upstream commit e076ab2a2ca70a0270232067cd49f76cd92efe64 ]

Commit 38d715f494 ("btrfs: use btrfs_start_delalloc_roots in
shrink_delalloc") cleaned up how we do delalloc shrinking by utilizing
some infrastructure we have in place to flush inodes that we use for
device replace and snapshot.  However this introduced a pretty serious
performance regression.  To reproduce the user untarred the source
tarball of Firefox (360MiB xz compressed/1.5GiB uncompressed), and would
see it take anywhere from 5 to 20 times as long to untar in 5.10
compared to 5.9. This was observed on fast devices (SSD and better) and
not on HDD.

The root cause is because before we would generally use the normal
writeback path to reclaim delalloc space, and for this we would provide
it with the number of pages we wanted to flush.  The referenced commit
changed this to flush that many inodes, which drastically increased the
amount of space we were flushing in certain cases, which severely
affected performance.

We cannot revert this patch unfortunately because of 3d45f221ce62
("btrfs: fix deadlock when cloning inline extent and low on free
metadata space") which requires the ability to skip flushing inodes that
are being cloned in certain scenarios, which means we need to keep using
our flushing infrastructure or risk re-introducing the deadlock.

Instead to fix this problem we can go back to providing
btrfs_start_delalloc_roots with a number of pages to flush, and then set
up a writeback_control and utilize sync_inode() to handle the flushing
for us.  This gives us the same behavior we had prior to the fix, while
still allowing us to avoid the deadlock that was fixed by Filipe.  I
redid the users original test and got the following results on one of
our test machines (256GiB of ram, 56 cores, 2TiB Intel NVMe drive)

  5.9		0m54.258s
  5.10		1m26.212s
  5.10+patch	0m38.800s

5.10+patch is significantly faster than plain 5.9 because of my patch
series "Change data reservations to use the ticketing infra" which
contained the patch that introduced the regression, but generally
improved the overall ENOSPC flushing mechanisms.

Additional testing on consumer-grade SSD (8GiB ram, 8 CPU) confirm
the results:

  5.10.5            4m00s
  5.10.5+patch      1m08s
  5.11-rc2	    5m14s
  5.11-rc2+patch    1m30s

Reported-by: René Rebe <rene@exactcode.de>
Fixes: 38d715f494 ("btrfs: use btrfs_start_delalloc_roots in shrink_delalloc")
CC: stable@vger.kernel.org # 5.10
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Tested-by: David Sterba <dsterba@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add my test results ]
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-17 14:16:54 +01:00
Filipe Manana
17243f73ad btrfs: fix deadlock when cloning inline extent and low on free metadata space
[ Upstream commit 3d45f221ce627d13e2e6ef3274f06750c84a6542 ]

When cloning an inline extent there are cases where we can not just copy
the inline extent from the source range to the target range (e.g. when the
target range starts at an offset greater than zero). In such cases we copy
the inline extent's data into a page of the destination inode and then
dirty that page. However, after that we will need to start a transaction
for each processed extent and, if we are ever low on available metadata
space, we may need to flush existing delalloc for all dirty inodes in an
attempt to release metadata space - if that happens we may deadlock:

* the async reclaim task queued a delalloc work to flush delalloc for
  the destination inode of the clone operation;

* the task executing that delalloc work gets blocked waiting for the
  range with the dirty page to be unlocked, which is currently locked
  by the task doing the clone operation;

* the async reclaim task blocks waiting for the delalloc work to complete;

* the cloning task is waiting on the waitqueue of its reservation ticket
  while holding the range with the dirty page locked in the inode's
  io_tree;

* if metadata space is not released by some other task (like delalloc for
  some other inode completing for example), the clone task waits forever
  and as a consequence the delalloc work and async reclaim tasks will hang
  forever as well. Releasing more space on the other hand may require
  starting a transaction, which will hang as well when trying to reserve
  metadata space, resulting in a deadlock between all these tasks.

When this happens, traces like the following show up in dmesg/syslog:

  [87452.323003] INFO: task kworker/u16:11:1810830 blocked for more than 120 seconds.
  [87452.323644]       Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  [87452.324248] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [87452.324852] task:kworker/u16:11  state:D stack:    0 pid:1810830 ppid:     2 flags:0x00004000
  [87452.325520] Workqueue: btrfs-flush_delalloc btrfs_work_helper [btrfs]
  [87452.326136] Call Trace:
  [87452.326737]  __schedule+0x5d1/0xcf0
  [87452.327390]  schedule+0x45/0xe0
  [87452.328174]  lock_extent_bits+0x1e6/0x2d0 [btrfs]
  [87452.328894]  ? finish_wait+0x90/0x90
  [87452.329474]  btrfs_invalidatepage+0x32c/0x390 [btrfs]
  [87452.330133]  ? __mod_memcg_state+0x8e/0x160
  [87452.330738]  __extent_writepage+0x2d4/0x400 [btrfs]
  [87452.331405]  extent_write_cache_pages+0x2b2/0x500 [btrfs]
  [87452.332007]  ? lock_release+0x20e/0x4c0
  [87452.332557]  ? trace_hardirqs_on+0x1b/0xf0
  [87452.333127]  extent_writepages+0x43/0x90 [btrfs]
  [87452.333653]  ? lock_acquire+0x1a3/0x490
  [87452.334177]  do_writepages+0x43/0xe0
  [87452.334699]  ? __filemap_fdatawrite_range+0xa4/0x100
  [87452.335720]  __filemap_fdatawrite_range+0xc5/0x100
  [87452.336500]  btrfs_run_delalloc_work+0x17/0x40 [btrfs]
  [87452.337216]  btrfs_work_helper+0xf1/0x600 [btrfs]
  [87452.337838]  process_one_work+0x24e/0x5e0
  [87452.338437]  worker_thread+0x50/0x3b0
  [87452.339137]  ? process_one_work+0x5e0/0x5e0
  [87452.339884]  kthread+0x153/0x170
  [87452.340507]  ? kthread_mod_delayed_work+0xc0/0xc0
  [87452.341153]  ret_from_fork+0x22/0x30
  [87452.341806] INFO: task kworker/u16:1:2426217 blocked for more than 120 seconds.
  [87452.342487]       Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  [87452.343274] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [87452.344049] task:kworker/u16:1   state:D stack:    0 pid:2426217 ppid:     2 flags:0x00004000
  [87452.344974] Workqueue: events_unbound btrfs_async_reclaim_metadata_space [btrfs]
  [87452.345655] Call Trace:
  [87452.346305]  __schedule+0x5d1/0xcf0
  [87452.346947]  ? kvm_clock_read+0x14/0x30
  [87452.347676]  ? wait_for_completion+0x81/0x110
  [87452.348389]  schedule+0x45/0xe0
  [87452.349077]  schedule_timeout+0x30c/0x580
  [87452.349718]  ? _raw_spin_unlock_irqrestore+0x3c/0x60
  [87452.350340]  ? lock_acquire+0x1a3/0x490
  [87452.351006]  ? try_to_wake_up+0x7a/0xa20
  [87452.351541]  ? lock_release+0x20e/0x4c0
  [87452.352040]  ? lock_acquired+0x199/0x490
  [87452.352517]  ? wait_for_completion+0x81/0x110
  [87452.353000]  wait_for_completion+0xab/0x110
  [87452.353490]  start_delalloc_inodes+0x2af/0x390 [btrfs]
  [87452.353973]  btrfs_start_delalloc_roots+0x12d/0x250 [btrfs]
  [87452.354455]  flush_space+0x24f/0x660 [btrfs]
  [87452.355063]  btrfs_async_reclaim_metadata_space+0x1bb/0x480 [btrfs]
  [87452.355565]  process_one_work+0x24e/0x5e0
  [87452.356024]  worker_thread+0x20f/0x3b0
  [87452.356487]  ? process_one_work+0x5e0/0x5e0
  [87452.356973]  kthread+0x153/0x170
  [87452.357434]  ? kthread_mod_delayed_work+0xc0/0xc0
  [87452.357880]  ret_from_fork+0x22/0x30
  (...)
  < stack traces of several tasks waiting for the locks of the inodes of the
    clone operation >
  (...)
  [92867.444138] RSP: 002b:00007ffc3371bbe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
  [92867.444624] RAX: ffffffffffffffda RBX: 00007ffc3371bea0 RCX: 00007f61efe73f97
  [92867.445116] RDX: 0000000000000000 RSI: 0000560fbd5d7a40 RDI: 0000560fbd5d8960
  [92867.445595] RBP: 00007ffc3371beb0 R08: 0000000000000001 R09: 0000000000000003
  [92867.446070] R10: 00007ffc3371b996 R11: 0000000000000246 R12: 0000000000000000
  [92867.446820] R13: 000000000000001f R14: 00007ffc3371bea0 R15: 00007ffc3371beb0
  [92867.447361] task:fsstress        state:D stack:    0 pid:2508238 ppid:2508153 flags:0x00004000
  [92867.447920] Call Trace:
  [92867.448435]  __schedule+0x5d1/0xcf0
  [92867.448934]  ? _raw_spin_unlock_irqrestore+0x3c/0x60
  [92867.449423]  schedule+0x45/0xe0
  [92867.449916]  __reserve_bytes+0x4a4/0xb10 [btrfs]
  [92867.450576]  ? finish_wait+0x90/0x90
  [92867.451202]  btrfs_reserve_metadata_bytes+0x29/0x190 [btrfs]
  [92867.451815]  btrfs_block_rsv_add+0x1f/0x50 [btrfs]
  [92867.452412]  start_transaction+0x2d1/0x760 [btrfs]
  [92867.453216]  clone_copy_inline_extent+0x333/0x490 [btrfs]
  [92867.453848]  ? lock_release+0x20e/0x4c0
  [92867.454539]  ? btrfs_search_slot+0x9a7/0xc30 [btrfs]
  [92867.455218]  btrfs_clone+0x569/0x7e0 [btrfs]
  [92867.455952]  btrfs_clone_files+0xf6/0x150 [btrfs]
  [92867.456588]  btrfs_remap_file_range+0x324/0x3d0 [btrfs]
  [92867.457213]  do_clone_file_range+0xd4/0x1f0
  [92867.457828]  vfs_clone_file_range+0x4d/0x230
  [92867.458355]  ? lock_release+0x20e/0x4c0
  [92867.458890]  ioctl_file_clone+0x8f/0xc0
  [92867.459377]  do_vfs_ioctl+0x342/0x750
  [92867.459913]  __x64_sys_ioctl+0x62/0xb0
  [92867.460377]  do_syscall_64+0x33/0x80
  [92867.460842]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  (...)
  < stack traces of more tasks blocked on metadata reservation like the clone
    task above, because the async reclaim task has deadlocked >
  (...)

Another thing to notice is that the worker task that is deadlocked when
trying to flush the destination inode of the clone operation is at
btrfs_invalidatepage(). This is simply because the clone operation has a
destination offset greater than the i_size and we only update the i_size
of the destination file after cloning an extent (just like we do in the
buffered write path).

Since the async reclaim path uses btrfs_start_delalloc_roots() to trigger
the flushing of delalloc for all inodes that have delalloc, add a runtime
flag to an inode to signal it should not be flushed, and for inodes with
that flag set, start_delalloc_inodes() will simply skip them. When the
cloning code needs to dirty a page to copy an inline extent, set that flag
on the inode and then clear it when the clone operation finishes.

This could be sporadically triggered with test case generic/269 from
fstests, which exercises many fsstress processes running in parallel with
several dd processes filling up the entire filesystem.

CC: stable@vger.kernel.org # 5.9+
Fixes: 05a5a7621c ("Btrfs: implement full reflink support for inline extents")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-17 14:16:54 +01:00
Filipe Manana
8773816459 btrfs: skip unnecessary searches for xattrs when logging an inode
[ Upstream commit f2f121ab500d0457cc9c6f54269d21ffdf5bd304 ]

Every time we log an inode we lookup in the fs/subvol tree for xattrs and
if we have any, log them into the log tree. However it is very common to
have inodes without any xattrs, so doing the search wastes times, but more
importantly it adds contention on the fs/subvol tree locks, either making
the logging code block and wait for tree locks or making the logging code
making other concurrent operations block and wait.

The most typical use cases where xattrs are used are when capabilities or
ACLs are defined for an inode, or when SELinux is enabled.

This change makes the logging code detect when an inode does not have
xattrs and skip the xattrs search the next time the inode is logged,
unless the inode is evicted and loaded again or a xattr is added to the
inode. Therefore skipping the search for xattrs on inodes that don't ever
have xattrs and are fsynced with some frequency.

The following script that calls dbench was used to measure the impact of
this change on a VM with 8 CPUs, 16Gb of ram, using a raw NVMe device
directly (no intermediary filesystem on the host) and using a non-debug
kernel (default configuration on Debian distributions):

  $ cat test.sh
  #!/bin/bash

  DEV=/dev/sdk
  MNT=/mnt/sdk
  MOUNT_OPTIONS="-o ssd"

  mkfs.btrfs -f -m single -d single $DEV
  mount $MOUNT_OPTIONS $DEV $MNT

  dbench -D $MNT -t 200 40

  umount $MNT

The results before this change:

 Operation      Count    AvgLat    MaxLat
 ----------------------------------------
 NTCreateX    5761605     0.172   312.057
 Close        4232452     0.002    10.927
 Rename        243937     1.406   277.344
 Unlink       1163456     0.631   298.402
 Deltree          160    11.581   221.107
 Mkdir             80     0.003     0.005
 Qpathinfo    5221410     0.065   122.309
 Qfileinfo     915432     0.001     3.333
 Qfsinfo       957555     0.003     3.992
 Sfileinfo     469244     0.023    20.494
 Find         2018865     0.448   123.659
 WriteX       2874851     0.049   118.529
 ReadX        9030579     0.004    21.654
 LockX          18754     0.003     4.423
 UnlockX        18754     0.002     0.331
 Flush         403792    10.944   359.494

Throughput 908.444 MB/sec  40 clients  40 procs  max_latency=359.500 ms

The results after this change:

 Operation      Count    AvgLat    MaxLat
 ----------------------------------------
 NTCreateX    6442521     0.159   230.693
 Close        4732357     0.002    10.972
 Rename        272809     1.293   227.398
 Unlink       1301059     0.563   218.500
 Deltree          160     7.796    54.887
 Mkdir             80     0.008     0.478
 Qpathinfo    5839452     0.047   124.330
 Qfileinfo    1023199     0.001     4.996
 Qfsinfo      1070760     0.003     5.709
 Sfileinfo     524790     0.033    21.765
 Find         2257658     0.314   125.611
 WriteX       3211520     0.040   232.135
 ReadX        10098969     0.004    25.340
 LockX          20974     0.003     1.569
 UnlockX        20974     0.002     3.475
 Flush         451553    10.287   331.037

Throughput 1011.77 MB/sec  40 clients  40 procs  max_latency=331.045 ms

+10.8% throughput, -8.2% max latency

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-17 14:16:53 +01:00
Filipe Manana
5e84c99055 btrfs: send: fix wrong file path when there is an inode with a pending rmdir
commit 0b3f407e6728d990ae1630a02c7b952c21c288d3 upstream.

When doing an incremental send, if we have a new inode that happens to
have the same number that an old directory inode had in the base snapshot
and that old directory has a pending rmdir operation, we end up computing
a wrong path for the new inode, causing the receiver to fail.

Example reproducer:

  $ cat test-send-rmdir.sh
  #!/bin/bash

  DEV=/dev/sdi
  MNT=/mnt/sdi

  mkfs.btrfs -f $DEV >/dev/null
  mount $DEV $MNT

  mkdir $MNT/dir
  touch $MNT/dir/file1
  touch $MNT/dir/file2
  touch $MNT/dir/file3

  # Filesystem looks like:
  #
  # .                                     (ino 256)
  # |----- dir/                           (ino 257)
  #         |----- file1                  (ino 258)
  #         |----- file2                  (ino 259)
  #         |----- file3                  (ino 260)
  #

  btrfs subvolume snapshot -r $MNT $MNT/snap1
  btrfs send -f /tmp/snap1.send $MNT/snap1

  # Now remove our directory and all its files.
  rm -fr $MNT/dir

  # Unmount the filesystem and mount it again. This is to ensure that
  # the next inode that is created ends up with the same inode number
  # that our directory "dir" had, 257, which is the first free "objectid"
  # available after mounting again the filesystem.
  umount $MNT
  mount $DEV $MNT

  # Now create a new file (it could be a directory as well).
  touch $MNT/newfile

  # Filesystem now looks like:
  #
  # .                                     (ino 256)
  # |----- newfile                        (ino 257)
  #

  btrfs subvolume snapshot -r $MNT $MNT/snap2
  btrfs send -f /tmp/snap2.send -p $MNT/snap1 $MNT/snap2

  # Now unmount the filesystem, create a new one, mount it and try to apply
  # both send streams to recreate both snapshots.
  umount $DEV

  mkfs.btrfs -f $DEV >/dev/null

  mount $DEV $MNT

  btrfs receive -f /tmp/snap1.send $MNT
  btrfs receive -f /tmp/snap2.send $MNT

  umount $MNT

When running the test, the receive operation for the incremental stream
fails:

  $ ./test-send-rmdir.sh
  Create a readonly snapshot of '/mnt/sdi' in '/mnt/sdi/snap1'
  At subvol /mnt/sdi/snap1
  Create a readonly snapshot of '/mnt/sdi' in '/mnt/sdi/snap2'
  At subvol /mnt/sdi/snap2
  At subvol snap1
  At snapshot snap2
  ERROR: chown o257-9-0 failed: No such file or directory

So fix this by tracking directories that have a pending rmdir by inode
number and generation number, instead of only inode number.

A test case for fstests follows soon.

Reported-by: Massimo B. <massimo.b@gmx.net>
Tested-by: Massimo B. <massimo.b@gmx.net>
Link: https://lore.kernel.org/linux-btrfs/6ae34776e85912960a253a8327068a892998e685.camel@gmx.net/
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-12 20:18:24 +01:00
Qu Wenruo
1888e5df84 btrfs: qgroup: don't try to wait flushing if we're already holding a transaction
commit ae5e070eaca9dbebde3459dd8f4c2756f8c097d0 upstream.

There is a chance of racing for qgroup flushing which may lead to
deadlock:

	Thread A		|	Thread B
   (not holding trans handle)	|  (holding a trans handle)
--------------------------------+--------------------------------
__btrfs_qgroup_reserve_meta()   | __btrfs_qgroup_reserve_meta()
|- try_flush_qgroup()		| |- try_flush_qgroup()
   |- QGROUP_FLUSHING bit set   |    |
   |				|    |- test_and_set_bit()
   |				|    |- wait_event()
   |- btrfs_join_transaction()	|
   |- btrfs_commit_transaction()|

			!!! DEAD LOCK !!!

Since thread A wants to commit transaction, but thread B is holding a
transaction handle, blocking the commit.
At the same time, thread B is waiting for thread A to finish its commit.

This is just a hot fix, and would lead to more EDQUOT when we're near
the qgroup limit.

The proper fix would be to make all metadata/data reservations happen
without holding a transaction handle.

CC: stable@vger.kernel.org # 5.9+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-12 20:18:24 +01:00
Filipe Manana
8f4bf6eea3 btrfs: fix race when defragmenting leads to unnecessary IO
commit 7f458a3873ae94efe1f37c8b96c97e7298769e98 upstream.

When defragmenting we skip ranges that have holes or inline extents, so that
we don't do unnecessary IO and waste space. We do this check when calling
should_defrag_range() at btrfs_defrag_file(). However we do it without
holding the inode's lock. The reason we do it like this is to avoid
blocking other tasks for too long, that possibly want to operate on other
file ranges, since after the call to should_defrag_range() and before
locking the inode, we trigger a synchronous page cache readahead. However
before we were able to lock the inode, some other task might have punched
a hole in our range, or we may now have an inline extent there, in which
case we should not set the range for defrag anymore since that would cause
unnecessary IO and make us waste space (i.e. allocating extents to contain
zeros for a hole).

So after we locked the inode and the range in the iotree, check again if
we have holes or an inline extent, and if we do, just skip the range.

I hit this while testing my next patch that fixes races when updating an
inode's number of bytes (subject "btrfs: update the number of bytes used
by an inode atomically"), and it depends on this change in order to work
correctly. Alternatively I could rework that other patch to detect holes
and flag their range with the 'new delalloc' bit, but this itself fixes
an efficiency problem due a race that from a functional point of view is
not harmful (it could be triggered with btrfs/062 from fstests).

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-30 11:54:13 +01:00
Josef Bacik
5c5bc5738b btrfs: update last_byte_to_unpin in switch_commit_roots
commit 27d56e62e4748c2135650c260024e9904b8c1a0a upstream.

While writing an explanation for the need of the commit_root_sem for
btrfs_prepare_extent_commit, I realized we have a slight hole that could
result in leaked space if we have to do the old style caching.  Consider
the following scenario

 commit root
 +----+----+----+----+----+----+----+
 |\\\\|    |\\\\|\\\\|    |\\\\|\\\\|
 +----+----+----+----+----+----+----+
 0    1    2    3    4    5    6    7

 new commit root
 +----+----+----+----+----+----+----+
 |    |    |    |\\\\|    |    |\\\\|
 +----+----+----+----+----+----+----+
 0    1    2    3    4    5    6    7

Prior to this patch, we run btrfs_prepare_extent_commit, which updates
the last_byte_to_unpin, and then we subsequently run
switch_commit_roots.  In this example lets assume that
caching_ctl->progress == 1 at btrfs_prepare_extent_commit() time, which
means that cache->last_byte_to_unpin == 1.  Then we go and do the
switch_commit_roots(), but in the meantime the caching thread has made
some more progress, because we drop the commit_root_sem and re-acquired
it.  Now caching_ctl->progress == 3.  We swap out the commit root and
carry on to unpin.

The race can happen like:

  1) The caching thread was running using the old commit root when it
     found the extent for [2, 3);

  2) Then it released the commit_root_sem because it was in the last
     item of a leaf and the semaphore was contended, and set ->progress
     to 3 (value of 'last'), as the last extent item in the current leaf
     was for the extent for range [2, 3);

  3) Next time it gets the commit_root_sem, will start using the new
     commit root and search for a key with offset 3, so it never finds
     the hole for [2, 3).

  So the caching thread never saw [2, 3) as free space in any of the
  commit roots, and by the time finish_extent_commit() was called for
  the range [0, 3), ->last_byte_to_unpin was 1, so it only returned the
  subrange [0, 1) to the free space cache, skipping [2, 3).

In the unpin code we have last_byte_to_unpin == 1, so we unpin [0,1),
but do not unpin [2,3).  However because caching_ctl->progress == 3 we
do not see the newly freed section of [2,3), and thus do not add it to
our free space cache.  This results in us missing a chunk of free space
in memory (on disk too, unless we have a power failure before writing
the free space cache to disk).

Fix this by making sure the ->last_byte_to_unpin is set at the same time
that we swap the commit roots, this ensures that we will always be
consistent.

CC: stable@vger.kernel.org # 5.8+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ update changelog with Filipe's review comments ]
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-30 11:54:13 +01:00