The kobject should be pulled in via sysfs.h and that needs to include it
because it needs various definitions like kobj_attribute or kobject.
Signed-off-by: David Sterba <dsterba@suse.com>
The helpers to create block group and space info directories already
live in sysfs.c, move the deletion part there too.
Signed-off-by: David Sterba <dsterba@suse.com>
The last non-sysfs usage of space_info_ktype has been moved to a private
helper in previous patch so the variable can be made static.
Signed-off-by: David Sterba <dsterba@suse.com>
The last non-sysfs usage of btrfs_raid_ktype has been moved to a private
helper in previous patch so the variable can be made static.
Signed-off-by: David Sterba <dsterba@suse.com>
The part of link_block_group that just creates the sysfs object is
independent and can be factored out to a helper.
Signed-off-by: David Sterba <dsterba@suse.com>
__btrfs_reset_dev_stats() is a small helper function to reset devices stat
values, and is used only once, instead just open code it.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_dev_stat_reset() is an overdo in terms of wrapping. So this patch
open codes btrfs_dev_stat_reset().
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When we try to delete qgroups, we're pretty cautious, we make sure both
qgroups exist and there is a relationship between them, then try to
delete the relation.
This behavior is OK, but the problem is we need to two relation items,
and if we failed the first item deletion, we error out, leaving the
other relation item in qgroup tree.
Sometimes the error from del_qgroup_relation_item() could just be
-ENOENT, thus we can ignore that error and continue without any problem.
Further more, such cautious behavior makes qgroup relation deletion
impossible for orphan relation items.
This patch will enhance __del_qgroup_relation():
- If both qgroups and their relation items exist
Go the regular deletion routine and update their accounting if needed.
- If any qgroup or relation item doesn't exist
Then we still try to delete the orphan items anyway, but don't trigger
the accounting update.
By this, we try our best to remove relation items, and can handle orphan
relation items properly, while still keep the existing behavior for good
qgroup tree.
Reported-by: Andrei Borzenkov <arvidjaar@gmail.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If any call to find_first_clear_extent_bit() returns an unexpected result,
the test should fail and not just print an error message, otherwise it
makes detection of regressions much harder to notice.
Fixes: 1eaebb341d ("btrfs: Don't trim returned range based on input value in find_first_clear_extent_bit")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The test creates an extent io tree and sets several ranges with the
CHUNK_ALLOCATED and CHUNK_TRIMMED bits, resulting in the allocation of
several extent state structures. However the test never clears those
ranges, resulting in memory leaks of the extent state structures.
This is detected when CONFIG_BTRFS_DEBUG is set once we remove the
btrfs module (rmmod btrfs):
[57399.787918] BTRFS: state leak: start 67108864 end 75497471 state 1 in tree 1 refs 1
[57399.790155] BTRFS: state leak: start 33554432 end 67108863 state 33 in tree 1 refs 1
[57399.791941] BTRFS: state leak: start 1048576 end 4194303 state 33 in tree 1 refs 1
[57399.793753] BTRFS: state leak: start 67108864 end 75497471 state 1 in tree 1 refs 1
[57399.795188] BTRFS: state leak: start 33554432 end 67108863 state 33 in tree 1 refs 1
[57399.796453] BTRFS: state leak: start 1048576 end 4194303 state 33 in tree 1 refs 1
[57399.797765] BTRFS: state leak: start 67108864 end 75497471 state 1 in tree 1 refs 1
[57399.799049] BTRFS: state leak: start 33554432 end 67108863 state 33 in tree 1 refs 1
[57399.800142] BTRFS: state leak: start 1048576 end 4194303 state 33 in tree 1 refs 1
[57399.801126] BTRFS: state leak: start 67108864 end 75497471 state 1 in tree 1 refs 1
[57399.802106] BTRFS: state leak: start 33554432 end 67108863 state 33 in tree 1 refs 1
[57399.803119] BTRFS: state leak: start 1048576 end 4194303 state 33 in tree 1 refs 1
[57399.804153] BTRFS: state leak: start 67108864 end 75497471 state 1 in tree 1 refs 1
[57399.805196] BTRFS: state leak: start 33554432 end 67108863 state 33 in tree 1 refs 1
[57399.806191] BTRFS: state leak: start 1048576 end 4194303 state 33 in tree 1 refs 1
The start and end offsets reported correspond exactly to the ranges
used by the test.
So fix that by clearing all the ranges when the test finishes.
Fixes: 1eaebb341d ("btrfs: Don't trim returned range based on input value in find_first_clear_extent_bit")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add 'debug' directories to global sysfs and per-filesystem. This will
replace the debugfs directory. The sysfs location is simpler and builds
on top of the existing file hierarchy so there will hopefully be no more
questions about the sample debugfs file.
The directory is called 'debug' and only present under
CONFIG_BTRFS_DEBUG so this will not affect productions builds.
Signed-off-by: David Sterba <dsterba@suse.com>
extent-tree.c has a find_next_key that just walks up the path to find
the next key, but it is used for both the caching stuff and the snapshot
delete stuff. The snapshot deletion stuff is special so it can't really
use btrfs_find_next_key, but the caching thread stuff can. We just need
to fix btrfs_find_next_key to deal with ->skip_locking and then it works
exactly the same as the private find_next_key helper.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This is used in caching and reading block groups, so export it while we
move these chunks independently.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Man a lot of people use this stuff.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We'll need this to move the caching stuff around.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This will make it so we can move them easily.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ coding style updates ]
Signed-off-by: David Sterba <dsterba@suse.com>
These are relatively straightforward as well.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Another easy set to move over to block-group.c.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move these bits first as they are the easiest to move. Export two of
the helpers so they can be moved all at once.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor style updates ]
Signed-off-by: David Sterba <dsterba@suse.com>
This is prep work for moving all of the block group cache code into its
own file.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor comment updates ]
Signed-off-by: David Sterba <dsterba@suse.com>
This is prep work for moving block_group_cache around. Having this in
the header file makes the header file include need to be in a certain
order, which is awkward, so just move it into free-space-cache.c and
then we can re-arrange later.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Used only for in-memory state tracking.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The switch to open coded set/get has happend long time ago in
962a298f35 ("btrfs: kill the key type accessor helpers"), remove the
stray helpers.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The status of flush bio is tracked as a status bit, changed in commit
1c3063b6db ("btrfs: cleanup device states define
BTRFS_DEV_STATE_FLUSH_SENT"), the flush_bio_sent was forgotten.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The bulk of the work done when cloning extents, at ioctl.c:btrfs_clone(),
is done inside an if statement that checks if the found key has the type
BTRFS_EXTENT_DATA_KEY. That if statement is redundant however, because
btrfs_search_slot() always leaves us in a leaf slot that points to a key
that is always greater then or equals to the search key, and our search
key here has that type, and because we bail out before that if statement
if the key at the given leaf slot is greater then BTRFS_EXTENT_DATA_KEY.
Therefore just remove that if statement, not only because it is useless
but mostly because it increases the nesting/indentation level in this
function which is quite big and makes things a bit awkward whenever I need
to fix something that requires changing btrfs_clone() (and it has been
like that for many years already).
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Simplify the code by removing variables that don't bring any real value
as well as simplifying the checks when buidling the candidate list of
devices. No functional changes.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
join_running_log_trans checks btrfs_root::log_root outside of
btrfs_root::log_mutex to avoid contention on the mutex. Turns out this
check is not necessary because the two callers of join_running_log_trans
(both of which deal with removing entries from the tree-log during
unlink) explicitly check whether the respective inode has been logged in
the current transaction.
If it hasn't then it won't have any items in the tree-log and call path
will return before calling join_running_log_trans. If the check passes,
however, then it's guaranteed that btrfs_root::log_root is set because
the inode is logged.
Those guarantees allows us to remove the speculative as well as the
implicity and tricky memory barrier.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we need to start an inode caching thread, because none currently exists
on disk, we can wake up all waiters as soon as we mark the range starting
at root's highest objectid + 1 and ending at BTRFS_LAST_FREE_OBJECTID as
free, so that they don't need to wait for the caching thread to start and
do some progress. We follow the same approach within the caching thread,
since as soon as it finds a free range and marks it as free space in the
cache, it wakes up all waiters. So improve this by adding such a wakeup
call after marking that initial range as free space.
Fixes: a47d6b70e2 ("Btrfs: setup free ino caching in a more asynchronous way")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If the caching thread fails to allocate a path, it returns without waking
up any cache waiters, leaving them hang forever. Fix this by following the
same approach as when we fail to start the caching thread: print an error
message, disable inode caching and make the wakers fallback to non-caching
mode behaviour (calling btrfs_find_free_objectid()).
Fixes: 581bb05094 ("Btrfs: Cache free inode numbers in memory")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we fail to start the inode caching thread, we print an error message
and disable the inode cache, however we never wake up any waiters, so they
hang forever waiting for the caching to finish. Fix this by waking them
up and have them fallback to a call to btrfs_find_free_objectid().
Fixes: e60efa8425 ("Btrfs: avoid triggering bug_on() when we fail to start inode caching task")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we are able to load an existing inode cache off disk, we set the state
of the cache to BTRFS_CACHE_FINISHED, but we don't wake up any one waiting
for the cache to be available. This means that anyone waiting for the
cache to be available, waiting on the condition that either its state is
BTRFS_CACHE_FINISHED or its available free space is greather than zero,
can hang forever.
This could be observed running fstests with MOUNT_OPTIONS="-o inode_cache",
in particular test case generic/161 triggered it very frequently for me,
producing a trace like the following:
[63795.739712] BTRFS info (device sdc): enabling inode map caching
[63795.739714] BTRFS info (device sdc): disk space caching is enabled
[63795.739716] BTRFS info (device sdc): has skinny extents
[64036.653886] INFO: task btrfs-transacti:3917 blocked for more than 120 seconds.
[64036.654079] Not tainted 5.2.0-rc4-btrfs-next-50 #1
[64036.654143] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[64036.654232] btrfs-transacti D 0 3917 2 0x80004000
[64036.654239] Call Trace:
[64036.654258] ? __schedule+0x3ae/0x7b0
[64036.654271] schedule+0x3a/0xb0
[64036.654325] btrfs_commit_transaction+0x978/0xae0 [btrfs]
[64036.654339] ? remove_wait_queue+0x60/0x60
[64036.654395] transaction_kthread+0x146/0x180 [btrfs]
[64036.654450] ? btrfs_cleanup_transaction+0x620/0x620 [btrfs]
[64036.654456] kthread+0x103/0x140
[64036.654464] ? kthread_create_worker_on_cpu+0x70/0x70
[64036.654476] ret_from_fork+0x3a/0x50
[64036.654504] INFO: task xfs_io:3919 blocked for more than 120 seconds.
[64036.654568] Not tainted 5.2.0-rc4-btrfs-next-50 #1
[64036.654617] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[64036.654685] xfs_io D 0 3919 3633 0x00000000
[64036.654691] Call Trace:
[64036.654703] ? __schedule+0x3ae/0x7b0
[64036.654716] schedule+0x3a/0xb0
[64036.654756] btrfs_find_free_ino+0xa9/0x120 [btrfs]
[64036.654764] ? remove_wait_queue+0x60/0x60
[64036.654809] btrfs_create+0x72/0x1f0 [btrfs]
[64036.654822] lookup_open+0x6bc/0x790
[64036.654849] path_openat+0x3bc/0xc00
[64036.654854] ? __lock_acquire+0x331/0x1cb0
[64036.654869] do_filp_open+0x99/0x110
[64036.654884] ? __alloc_fd+0xee/0x200
[64036.654895] ? do_raw_spin_unlock+0x49/0xc0
[64036.654909] ? do_sys_open+0x132/0x220
[64036.654913] do_sys_open+0x132/0x220
[64036.654926] do_syscall_64+0x60/0x1d0
[64036.654933] entry_SYSCALL_64_after_hwframe+0x49/0xbe
Fix this by adding a wake_up() call right after setting the cache state to
BTRFS_CACHE_FINISHED, at start_caching(), when we are able to load the
cache from disk.
Fixes: 82d5902d9c ("Btrfs: Support reading/writing on disk free ino cache")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This patch will introduce ROOT_ITEM check, which includes:
- Key->objectid and key->offset check
Currently only some easy check, e.g. 0 as rootid is invalid.
- Item size check
Root item size is fixed.
- Generation checks
Generation, generation_v2 and last_snapshot should not be greater than
super generation + 1
- Level and alignment check
Level should be in [0, 7], and bytenr must be aligned to sector size.
- Flags check
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203261
Reported-by: Jungyeon Yoon <jungyeon.yoon@gmail.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
With fuzzed image and MIXED_GROUPS super flag, we can hit the following
BUG_ON():
kernel BUG at fs/btrfs/delayed-ref.c:491!
invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
CPU: 0 PID: 1849 Comm: sync Tainted: G O 5.2.0-custom #27
RIP: 0010:update_existing_head_ref.cold+0x44/0x46 [btrfs]
Call Trace:
add_delayed_ref_head+0x20c/0x2d0 [btrfs]
btrfs_add_delayed_tree_ref+0x1fc/0x490 [btrfs]
btrfs_free_tree_block+0x123/0x380 [btrfs]
__btrfs_cow_block+0x435/0x500 [btrfs]
btrfs_cow_block+0x110/0x240 [btrfs]
btrfs_search_slot+0x230/0xa00 [btrfs]
? __lock_acquire+0x105e/0x1e20
btrfs_insert_empty_items+0x67/0xc0 [btrfs]
alloc_reserved_file_extent+0x9e/0x340 [btrfs]
__btrfs_run_delayed_refs+0x78e/0x1240 [btrfs]
? kvm_clock_read+0x18/0x30
? __sched_clock_gtod_offset+0x21/0x50
btrfs_run_delayed_refs.part.0+0x4e/0x180 [btrfs]
btrfs_run_delayed_refs+0x23/0x30 [btrfs]
btrfs_commit_transaction+0x53/0x9f0 [btrfs]
btrfs_sync_fs+0x7c/0x1c0 [btrfs]
? __ia32_sys_fdatasync+0x20/0x20
sync_fs_one_sb+0x23/0x30
iterate_supers+0x95/0x100
ksys_sync+0x62/0xb0
__ia32_sys_sync+0xe/0x20
do_syscall_64+0x65/0x240
entry_SYSCALL_64_after_hwframe+0x49/0xbe
[CAUSE]
This situation is caused by several factors:
- Fuzzed image
The extent tree of this fs missed one backref for extent tree root.
So we can allocated space from that slot.
- MIXED_BG feature
Super block has MIXED_BG flag.
- No mixed block groups exists
All block groups are just regular ones.
This makes data space_info->block_groups[] contains metadata block
groups. And when we reserve space for data, we can use space in
metadata block group.
Then we hit the following file operations:
- fallocate
We need to allocate data extents.
find_free_extent() choose to use the metadata block to allocate space
from, and choose the space of extent tree root, since its backref is
missing.
This generate one delayed ref head with is_data = 1.
- extent tree update
We need to update extent tree at run_delayed_ref time.
This generate one delayed ref head with is_data = 0, for the same
bytenr of old extent tree root.
Then we trigger the BUG_ON().
[FIX]
The quick fix here is to check block_group->flags before using it.
The problem can only happen for MIXED_GROUPS fs. Regular filesystems
won't have space_info with DATA|METADATA flag, and no way to hit the
bug.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203255
Reported-by: Jungyeon Yoon <jungyeon.yoon@gmail.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There is one report of fuzzed image which leads to BUG_ON() in
btrfs_delete_delayed_dir_index().
Although that fuzzed image can already be addressed by enhanced
extent-tree error handler, it's still better to hunt down more BUG_ON().
This patch will hunt down two BUG_ON()s in
btrfs_delete_delayed_dir_index():
- One for error from btrfs_delayed_item_reserve_metadata()
Instead of BUG_ON(), we output an error message and free the item.
And return the error.
All callers of this function handles the error by aborting current
trasaction.
- One for possible EEXIST from __btrfs_add_delayed_deletion_item()
That function can return -EEXIST.
We already have a good enough error message for that, only need to
clean up the reserved metadata space and allocated item.
To help above cleanup, also modifiy __btrfs_remove_delayed_item() called
in btrfs_release_delayed_item(), to skip unassociated item.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203253
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
Test case btrfs/156 fails since commit 302167c50b ("btrfs: don't end
the transaction for delayed refs in throttle") with ENOSPC.
[CAUSE]
The ENOSPC is reported from btrfs_can_relocate().
This function will check:
- If this block group is empty, we can relocate
- If we can enough free space, we can relocate
Above checks are valid but the following check is vague due to its
implementation:
- If and only if we can allocated a new block group to contain all the
used space, we can relocate
This design itself is OK, but the way to determine if we can allocate a
new block group is problematic.
btrfs_can_relocate() uses find_free_dev_extent() to find free space on a
device.
However find_free_dev_extent() only searches commit root and excludes
dev extents allocated in current trans, this makes it unable to use dev
extent just freed in current transaction.
So for the following example, btrfs_can_relocate() will report ENOSPC:
The example block group layout:
1M 129M 257M 385M 513M 550M
|///////|///////////|//////////| | |
// = Used bg, consider all bg is 100% used for easy calculation.
And all block groups are SINGLE, on-disk bytenr is the same as the
logical bytenr.
1) Bg in [129M, 257M) get relocated to [385M, 513M), transid=100
1M 129M 257M 385M 513M 550M
|///////| |//////////|/////////|
In transid 100, bg in [129M, 257M) get relocated to [385M, 513M)
However transid 100 is not committed yet, so in dev commit tree, we
still have the old dev extents layout:
1M 129M 257M 385M 513M 550M
|///////|///////////|//////////| | |
2) Try to relocate bg [257M, 385M)
We goes into btrfs_can_relocate(), no free space in current bgs, so we
check if we can find large enough free dev extents.
The first slot is [385M, 513M), but that is already used by new bg at
[385M, 513M), so we continue search.
The remaining slot is [512M, 550M), smaller than the bg's length 128M.
So btrfs_can_relocate report ENOSPC.
However this is over killed, in fact if we just skip btrfs_can_relocate()
check, and go into regular relocation routine, at extent reservation time,
if we can't find free extent, then we fallback to commit transaction,
which will free up the dev extents and allow new block group to be created.
[FIX]
The fix here is to remove btrfs_can_relocate() completely.
If we hit the false ENOSPC case just like btrfs/156, extent allocator
will push harder by committing transaction and we will have space for
new block group, avoiding the false ENOSPC.
If we really ran out of space, we will hit ENOSPC at
relocate_block_group(), and btrfs will just reports the ENOSPC error as
usual.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
inc_block_group_ro() is only designed to mark one block group read-only,
it doesn't really care if other block groups have enough free space to
contain the used space in the block group.
However due to the close connection between this function and
relocation, sometimes we can be confused and think this function is
responsible for balance space reservation, which is not true.
Add some comment to make the functionality clear.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Since commit 6df9a95e63 ("Btrfs: make the chunk allocator completely
tree lockless") we search commit root of device tree to avoid deadlock.
This introduced a safety feature, find_free_dev_extent_start() won't
use dev extents which just get freed in current transaction.
This safety feature makes sure we won't allocate new block group using
just freed dev extents to break CoW.
However, this feature also makes find_free_dev_extent_start() not
reliable reporting free device space. Just add such comment to make
later viewer careful about this behavior.
This behavior makes one caller, btrfs_can_relocate() unreliable
determining the device free space.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This function is only used locally in find_free_dev_extent(), no
external callers.
So unexport it.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The tree is going to be modified so it must be the exclusive lock.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
