Commit Graph

8056 Commits

Author SHA1 Message Date
Qu Wenruo
a94d1d0cb3 btrfs: Flush before reflinking any extent to prevent NOCOW write falling back to COW without data reservation
[BUG]
The following script can cause unexpected fsync failure:

  #!/bin/bash

  dev=/dev/test/test
  mnt=/mnt/btrfs

  mkfs.btrfs -f $dev -b 512M > /dev/null
  mount $dev $mnt -o nospace_cache

  # Prealloc one extent
  xfs_io -f -c "falloc 8k 64m" $mnt/file1
  # Fill the remaining data space
  xfs_io -f -c "pwrite 0 -b 4k 512M" $mnt/padding
  sync

  # Write into the prealloc extent
  xfs_io -c "pwrite 1m 16m" $mnt/file1

  # Reflink then fsync, fsync would fail due to ENOSPC
  xfs_io -c "reflink $mnt/file1 8k 0 4k" -c "fsync" $mnt/file1
  umount $dev

The fsync fails with ENOSPC, and the last page of the buffered write is
lost.

[CAUSE]
This is caused by:
- Btrfs' back reference only has extent level granularity
  So write into shared extent must be COWed even only part of the extent
  is shared.

So for above script we have:
- fallocate
  Create a preallocated extent where we can do NOCOW write.

- fill all the remaining data and unallocated space

- buffered write into preallocated space
  As we have not enough space available for data and the extent is not
  shared (yet) we fall into NOCOW mode.

- reflink
  Now part of the large preallocated extent is shared, later write
  into that extent must be COWed.

- fsync triggers writeback
  But now the extent is shared and therefore we must fallback into COW
  mode, which fails with ENOSPC since there's not enough space to
  allocate data extents.

[WORKAROUND]
The workaround is to ensure any buffered write in the related extents
(not just the reflink source range) get flushed before reflink/dedupe,
so that NOCOW writes succeed that happened before reflinking succeed.

The workaround is expensive, we could do it better by only flushing
NOCOW range, but that needs extra accounting for NOCOW range.
For now, fix the possible data loss first.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:35:00 +02:00
Nikolay Borisov
5f791ec31f btrfs: Return EAGAIN if we can't start no snpashot write in check_can_nocow
The first thing code does in check_can_nocow is trying to block
concurrent snapshots. If this fails (due to snpashot already being in
progress) the function returns ENOSPC which makes no sense. Instead
return EAGAIN. Despite this return value not being propagated to callers
it's good practice to return the closest in terms of semantics error
code. 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>
2019-07-01 13:34:59 +02:00
Nikolay Borisov
0b6f5d408b btrfs: Add comments on locking of several device-related fields
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:59 +02:00
Nikolay Borisov
bd80d94efb btrfs: Always use a cached extent_state in btrfs_lock_and_flush_ordered_range
In case no cached_state argument is passed to
btrfs_lock_and_flush_ordered_range use one locally in the function. This
optimises the case when an ordered extent is found since the unlock
function will be able to unlock that state directly without searching
for it again.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:59 +02:00
Nikolay Borisov
23d31bd476 btrfs: Use newly introduced btrfs_lock_and_flush_ordered_range
There several functions which open code
btrfs_lock_and_flush_ordered_range, just replace them with a call to the
function. No functional changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:59 +02:00
Nikolay Borisov
ffa87214c1 btrfs: add new helper btrfs_lock_and_flush_ordered_range
There is a certain idiom used in multiple places in btrfs' codebase,
dealing with flushing an ordered range. Factor this in a separate
function that can be reused. Future patches will replace the existing
code with that function.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:59 +02:00
Qu Wenruo
1200b51f57 btrfs: remove the incorrect comment on RO fs when btrfs_run_delalloc_range() fails
At the context of btrfs_run_delalloc_range(), we haven't started/joined
a transaction, thus even something went wrong, we can't and won't abort
transaction, thus no way to make the fs RO.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:59 +02:00
Qu Wenruo
480b9b4d84 btrfs: extent-tree: Add trace events for space info numbers update
Add trace event for update_bytes_pinned() and update_bytes_may_use() to
detect underflow better.

The output would be something like (only showing data part):

  ## Buffered write start, 16K total ##
  2255.954 xfs_io/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=0 diff=4096
  2257.169 sudo/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=4096 diff=4096
  2257.346 sudo/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=8192 diff=4096
  2257.542 sudo/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=12288 diff=4096

  ## Delalloc start ##
  3727.853 kworker/u8:3-e/700 btrfs:update_bytes_may_use:(nil)U: type=DATA old=16384 diff=-16384

  ## Space cache update ##
  3733.132 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=0 diff=65536
  3733.169 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=65536 diff=-65536
  3739.868 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=0 diff=65536
  3739.891 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=65536 diff=-65536

These two trace events will allow bcc tool to probe btrfs_space_info
changes and detect underflow with more details (e.g. backtrace for each
update).

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:58 +02:00
Qu Wenruo
0185f364cb btrfs: extent-tree: Add lockdep assert when updating space info
Just add a safe net for btrfs_space_info member updating.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:58 +02:00
David Sterba
cff8267228 btrfs: read number of data stripes from map only once
There are several places that call nr_data_stripes, but this value does
not change.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:58 +02:00
David Sterba
72ad813157 btrfs: constify map parameter for nr_parity_stripes and nr_data_stripes
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:58 +02:00
David Sterba
158da513b1 btrfs: refactor helper for bg flags to name conversion
The helper lacks the btrfs_ prefix and the parameter is the raw
blockgroup type, so none of the callers has to do the flags -> index
conversion.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:58 +02:00
David Sterba
e3ecdb3fde btrfs: factor out devs_max setting in __btrfs_alloc_chunk
Merge the repeated code before the if-else block.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:57 +02:00
David Sterba
8c3e3582a4 btrfs: use u8 for raid_array members
The raid_attr table is now 7 * 56 = 392 bytes long, consisting of just
small numbers so we don't have to use ints. New size is 7 * 32 = 224,
saving 3 cachelines.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:57 +02:00
David Sterba
946c9256c6 btrfs: factor out helper for counting data stripes
Factor the sequence of ifs to a helper, the 'data stripes' here means
the number of stripes without redundancy and parity.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:57 +02:00
David Sterba
44b28adafd btrfs: use raid_attr table for btrfs_bg_type_to_factor
The factor is the number of copies.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:57 +02:00
David Sterba
6079e12cdb btrfs: use raid_attr table to find profiles for integrity lowering
Replace open coded list of the profiles by selecting them from the
raid_attr table. The criteria are now more explicit, we need profiles
that have more than 1 copy of the data or can reconstruct the data with
a missing device.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:57 +02:00
David Sterba
081db89b13 btrfs: use raid_attr to get allowed profiles for balance conversion
Iterate over the table and gather all allowed profiles for a given
number of devices, instead of open coding.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:56 +02:00
David Sterba
fc9a2ac77c btrfs: use raid_attr in btrfs_chunk_max_errors
The number of tolerated failures is stored in the raid_attr table, use
it.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:56 +02:00
David Sterba
9fa02ac75b btrfs: use raid_attr table in get_profile_num_devs
The dev_max constraints are defined in the raid_attr table, use it
instead of open-coding it.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:56 +02:00
David Sterba
c8bf1b6703 btrfs: remove mapping tree structures indirection
fs_info::mapping_tree is the physical<->logical mapping tree and uses
the same underlying structure as extents, but is embedded to another
structure. There are no other members and this indirection is useless.
No functional change.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:56 +02:00
David Sterba
49cc180ca9 btrfs: raid56: allow the exact minimum number of devices for balance convert
The minimum number of devices for RAID5 is 2, though this is only a bit
expensive RAID1, and for RAID6 it's 3, which is a triple copy that works
only 3 devices.

mkfs.btrfs allows that and mounting such filesystem also works, so the
conversion via balance filters is inconsistent with the others and we
should not prevent it.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:56 +02:00
David Sterba
0ee5f8ae08 btrfs: fix minimum number of chunk errors for DUP
The list of profiles in btrfs_chunk_max_errors lists DUP as a profile
DUP able to tolerate 1 device missing. Though this profile is special
with 2 copies, it still needs the device, unlike the others.

Looking at the history of changes, thre's no clear reason why DUP is
there, functions were refactored and blocks of code merged to one
helper.

d20983b40e Btrfs: fix writing data into the seed filesystem
  - factor code to a helper

de11cc12df Btrfs: don't pre-allocate btrfs bio
  - unrelated change, DUP still in the list with max errors 1

a236aed14c Btrfs: Deal with failed writes in mirrored configurations
  - introduced the max errors, leaves DUP and RAID1 in the same group

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:55 +02:00
Liu Bo
be9b8dfa9c Btrfs: remove unused variables in __btrfs_unlink_inode
This code was first introduced in 5f39d397df ("Btrfs: Create
extent_buffer interface for large blocksizes") and the function was
named btrfs_unlink_trans. It later got renamed to __btrfs_unlink_inode
and finally commit 16cdcec736 ("btrfs: implement delayed inode items
operation") changed the way inodes are deleted and obviated the need for
those two members.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ replace changelog by Nikolay's version ]
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:55 +02:00
Goldwyn Rodrigues
cebf05ca65 btrfs: Remove unused variable mode in btrfs_mount
This is a leftover from 312c89fbca ("btrfs: cleanup btrfs_mount()
using btrfs_mount_root()"), the mode was used for opening devices that's
not done here anymore.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:55 +02:00
Su Yue
8f63a84051 btrfs: switch order of unlocks of space_info and bg in do_trimming()
In function do_trimming(), block_group->lock should be unlocked first,
as the locks should be released in the reverse order. This does not
cause problems but should follow the best practices.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:55 +02:00
Qu Wenruo
4c094c33c9 btrfs: tree-checker: Check if the file extent end overflows
Under certain conditions, we could have strange file extent item in log
tree like:

  item 18 key (69599 108 397312) itemoff 15208 itemsize 53
	extent data disk bytenr 0 nr 0
	extent data offset 0 nr 18446744073709547520 ram 18446744073709547520

The num_bytes + ram_bytes overflow 64 bit type.

For num_bytes part, we can detect such overflow along with file offset
(key->offset), as file_offset + num_bytes should never go beyond u64.

For ram_bytes part, it's about the decompressed size of the extent, not
directly related to the size.
In theory it is OK to have a large value, and put extra limitation
on RAM bytes may cause unexpected false alerts.

So in tree-checker, we only check if the file offset and num bytes
overflow.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:55 +02:00
Nikolay Borisov
2ed95d2d59 btrfs: Remove redundant assignment of tgt_device->commit_total_bytes
This is already done in btrfs_init_dev_replace_tgtdev which is the first
phase of device replace, called before doing scrub. During that time
exclusive lock is held. Additionally btrfs_fs_device::commit_total_bytes
is always set based on the size of the underlying block device which
shouldn't change once set. This makes the 2nd assignment of the variable
in the finishing phase redundant.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:55 +02:00
Nikolay Borisov
f232ab04f6 btrfs: Explicitly reserve space for devreplace item
Part of device replace involves writing an item to the device root
containing information about pending replace operations. Currently space
for this item is not being explicitly reserved so this works thanks to
presence of global reserve. While not fatal it's not a good practice.
Let's be explicit about space requirement of device replace and reserve
space when starting the transaction.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:54 +02:00
Nikolay Borisov
fa19452a40 btrfs: Streamline replace sem unlock in btrfs_dev_replace_start
There are only 2 branches which goto leave label with need_unlock set
to true. Essentially need_unlock is used as a substitute for directly
calling up_write. Since the branches needing this are only 2 and their
context is not that big it's more clear to just call up_write where
required. No functional changes.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:54 +02:00
Nikolay Borisov
e1e0eb43ce btrfs: Ensure btrfs_init_dev_replace_tgtdev sees up to date values
btrfs_init_dev_replace_tgtdev reads certain values from the source
device (such as commit_total_bytes) which are updated during transaction
commit. Currently this function is called before committing any pending
transaction, leading to possibly reading outdated values.

Fix this by moving the function below the transaction commit, at this
point the EXCL_OP bit it set hence once transaction is complete the
total size of the device cannot be changed (it's usually changed by
resize/remove ops which are blocked).

Fixes: 9e271ae27e ("Btrfs: kernel operation should come after user input has been verified")
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:54 +02:00
Nikolay Borisov
419684b2c2 btrfs: dev-replace: Remove impossible WARN_ON
This WARN_ON can never trigger because src_device cannot be null.
btrfs_find_device_by_devspec always returns either an error or a valid
pointer to the device. Just remove it.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:54 +02:00
Nikolay Borisov
b0d9e1ea17 btrfs: Reduce critical section in btrfs_init_dev_replace_tgtdev
There is no point in holding btrfs_fs_devices::device_list_mutex
while initialising fields of the not-yet-published device. Instead,
hold the mutex only when the newly initialised device is being
published. I think holding device_list_mutex here is redundant
altogether, because at this point BTRFS_FS_EXCL_OP is set which
prevents device removal/addition/balance/resize to occur.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:54 +02:00
Nikolay Borisov
ddb9378469 btrfs: Don't opencode sync_blockdev in btrfs_init_dev_replace_tgtdev
Using sync_blockdev makes it plain obvious what's happening. No
functional changes.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:53 +02:00
David Sterba
5911c8fe05 btrfs: fiemap: preallocate ulists for btrfs_check_shared
btrfs_check_shared looks up parents of a given extent and uses ulists
for that. These are allocated and freed repeatedly. Preallocation in the
caller will avoid the overhead and also allow us to use the GFP_KERNEL
as it is happens before the extent locks are taken.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:53 +02:00
David Sterba
9b4e675a99 btrfs: detect fast implementation of crc32c on all architectures
Currently, there's only check for fast crc32c implementation on X86,
based on the CPU flags. This is used to decide if checksumming should be
offloaded to worker threads or can be calculated by the caller.

As there are more architectures that implement a faster version of
crc32c (ARM, SPARC, s390, MIPS, PowerPC), also there are specialized hw
cards.

The detection is based on driver name, all generic C implementations
contain 'generic', while the specialized versions do not. Alternatively
the priority could be used, but this is not currently provided by the
crypto API.

The flag is set per-filesystem at mount time and used for the offloading
decisions.

Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:53 +02:00
Qu Wenruo
78192442d3 btrfs: extent-tree: Refactor add_pinned_bytes() to add|sub_pinned_bytes()
Instead of using @sign to determine whether we're adding or subtracting.
Even it only has 3 callers, it's still (and in fact already caused
problem in the past) confusing to use.

Refactor add_pinned_bytes() to add_pinned_bytes() and sub_pinned_bytes()
to explicitly show what we're doing.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-01 13:34:53 +02:00
Linus Torvalds
bed3c0d84e for-5.2-rc5-tag
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Merge tag 'for-5.2-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:

 - regression where properties stored as xattrs are not properly
   persisted

 - a small readahead fix (the fstests testcase for that fix hangs on
   unpatched kernel, so we'd like get it merged to ease future testing)

 - fix a race during block group creation and deletion

* tag 'for-5.2-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  Btrfs: fix failure to persist compression property xattr deletion on fsync
  btrfs: start readahead also in seed devices
  Btrfs: fix race between block group removal and block group allocation
2019-06-18 11:20:24 -07:00
Filipe Manana
3763771cf6 Btrfs: fix failure to persist compression property xattr deletion on fsync
After the recent series of cleanups in the properties and xattrs modules
that landed in the 5.2 merge window, we ended up with a regression where
after deleting the compression xattr property through the setflags ioctl,
we don't set the BTRFS_INODE_COPY_EVERYTHING flag in the inode anymore.
As a consequence, if the inode was fsync'ed when it had the compression
property set, after deleting the compression property through the setflags
ioctl and fsync'ing again the inode, the log will still contain the
compression xattr, because the inode did not had that bit set, which
made the fsync not delete all xattrs from the log and copy all xattrs
from the subvolume tree to the log tree.

This regression happens due to the fact that that series of cleanups
made btrfs_set_prop() call the old function do_setxattr() (which is now
named btrfs_setxattr()), and not the old version of btrfs_setxattr(),
which is now called btrfs_setxattr_trans().

Fix this by setting the BTRFS_INODE_COPY_EVERYTHING bit in the current
btrfs_setxattr() function and remove it from everywhere else, including
its setup at btrfs_ioctl_setflags(). This is cleaner, avoids similar
regressions in the future, and centralizes the setup of the bit. After
all, the need to setup this bit should only be in the xattrs module,
since it is an implementation of xattrs.

Fixes: 04e6863b19 ("btrfs: split btrfs_setxattr calls regarding transaction")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-06-17 16:37:17 +02:00
Naohiro Aota
c4e0540d0a btrfs: start readahead also in seed devices
Currently, btrfs does not consult seed devices to start readahead. As a
result, if readahead zone is added to the seed devices, btrfs_reada_wait()
indefinitely wait for the reada_ctl to finish.

You can reproduce the hung by modifying btrfs/163 to have larger initial
file size (e.g. xfs_io pwrite 4M instead of current 256K).

Fixes: 7414a03fbf ("btrfs: initial readahead code and prototypes")
Cc: stable@vger.kernel.org # 3.2+: ce7791ffee: Btrfs: fix race between readahead and device replace/removal
Cc: stable@vger.kernel.org # 3.2+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-06-14 17:33:46 +02:00
Filipe Manana
8eaf40c0e2 Btrfs: fix race between block group removal and block group allocation
If a task is removing the block group that currently has the highest start
offset amongst all existing block groups, there is a short time window
where it races with a concurrent block group allocation, resulting in a
transaction abort with an error code of EEXIST.

The following diagram explains the race in detail:

      Task A                                                        Task B

 btrfs_remove_block_group(bg offset X)

   remove_extent_mapping(em offset X)
     -> removes extent map X from the
        tree of extent maps
        (fs_info->mapping_tree), so the
        next call to find_next_chunk()
        will return offset X

                                                   btrfs_alloc_chunk()
                                                     find_next_chunk()
                                                       --> returns offset X

                                                     __btrfs_alloc_chunk(offset X)
                                                       btrfs_make_block_group()
                                                         btrfs_create_block_group_cache()
                                                           --> creates btrfs_block_group_cache
                                                               object with a key corresponding
                                                               to the block group item in the
                                                               extent, the key is:
                                                               (offset X, BTRFS_BLOCK_GROUP_ITEM_KEY, 1G)

                                                         --> adds the btrfs_block_group_cache object
                                                             to the list new_bgs of the transaction
                                                             handle

                                                   btrfs_end_transaction(trans handle)
                                                     __btrfs_end_transaction()
                                                       btrfs_create_pending_block_groups()
                                                         --> sees the new btrfs_block_group_cache
                                                             in the new_bgs list of the transaction
                                                             handle
                                                         --> its call to btrfs_insert_item() fails
                                                             with -EEXIST when attempting to insert
                                                             the block group item key
                                                             (offset X, BTRFS_BLOCK_GROUP_ITEM_KEY, 1G)
                                                             because task A has not removed that key yet
                                                         --> aborts the running transaction with
                                                             error -EEXIST

   btrfs_del_item()
     -> removes the block group's key from
        the extent tree, key is
        (offset X, BTRFS_BLOCK_GROUP_ITEM_KEY, 1G)

A sample transaction abort trace:

  [78912.403537] ------------[ cut here ]------------
  [78912.403811] BTRFS: Transaction aborted (error -17)
  [78912.404082] WARNING: CPU: 2 PID: 20465 at fs/btrfs/extent-tree.c:10551 btrfs_create_pending_block_groups+0x196/0x250 [btrfs]
  (...)
  [78912.405642] CPU: 2 PID: 20465 Comm: btrfs Tainted: G        W         5.0.0-btrfs-next-46 #1
  [78912.405941] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014
  [78912.406586] RIP: 0010:btrfs_create_pending_block_groups+0x196/0x250 [btrfs]
  (...)
  [78912.407636] RSP: 0018:ffff9d3d4b7e3b08 EFLAGS: 00010282
  [78912.407997] RAX: 0000000000000000 RBX: ffff90959a3796f0 RCX: 0000000000000006
  [78912.408369] RDX: 0000000000000007 RSI: 0000000000000001 RDI: ffff909636b16860
  [78912.408746] RBP: ffff909626758a58 R08: 0000000000000000 R09: 0000000000000000
  [78912.409144] R10: ffff9095ff462400 R11: 0000000000000000 R12: ffff90959a379588
  [78912.409521] R13: ffff909626758ab0 R14: ffff9095036c0000 R15: ffff9095299e1158
  [78912.409899] FS:  00007f387f16f700(0000) GS:ffff909636b00000(0000) knlGS:0000000000000000
  [78912.410285] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [78912.410673] CR2: 00007f429fc87cbc CR3: 000000014440a004 CR4: 00000000003606e0
  [78912.411095] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  [78912.411496] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  [78912.411898] Call Trace:
  [78912.412318]  __btrfs_end_transaction+0x5b/0x1c0 [btrfs]
  [78912.412746]  btrfs_inc_block_group_ro+0xcf/0x160 [btrfs]
  [78912.413179]  scrub_enumerate_chunks+0x188/0x5b0 [btrfs]
  [78912.413622]  ? __mutex_unlock_slowpath+0x100/0x2a0
  [78912.414078]  btrfs_scrub_dev+0x2ef/0x720 [btrfs]
  [78912.414535]  ? __sb_start_write+0xd4/0x1c0
  [78912.414963]  ? mnt_want_write_file+0x24/0x50
  [78912.415403]  btrfs_ioctl+0x17fb/0x3120 [btrfs]
  [78912.415832]  ? lock_acquire+0xa6/0x190
  [78912.416256]  ? do_vfs_ioctl+0xa2/0x6f0
  [78912.416685]  ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
  [78912.417116]  do_vfs_ioctl+0xa2/0x6f0
  [78912.417534]  ? __fget+0x113/0x200
  [78912.417954]  ksys_ioctl+0x70/0x80
  [78912.418369]  __x64_sys_ioctl+0x16/0x20
  [78912.418812]  do_syscall_64+0x60/0x1b0
  [78912.419231]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [78912.419644] RIP: 0033:0x7f3880252dd7
  (...)
  [78912.420957] RSP: 002b:00007f387f16ed68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
  [78912.421426] RAX: ffffffffffffffda RBX: 000055f5becc1df0 RCX: 00007f3880252dd7
  [78912.421889] RDX: 000055f5becc1df0 RSI: 00000000c400941b RDI: 0000000000000003
  [78912.422354] RBP: 0000000000000000 R08: 00007f387f16f700 R09: 0000000000000000
  [78912.422790] R10: 00007f387f16f700 R11: 0000000000000246 R12: 0000000000000000
  [78912.423202] R13: 00007ffda49c266f R14: 0000000000000000 R15: 00007f388145e040
  [78912.425505] ---[ end trace eb9bfe7c426fc4d3 ]---

Fix this by calling remove_extent_mapping(), at btrfs_remove_block_group(),
only at the very end, after removing the block group item key from the
extent tree (and removing the free space tree entry if we are using the
free space tree feature).

Fixes: 04216820fe ("Btrfs: fix race between fs trimming and block group remove/allocation")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-06-12 15:55:42 +02:00
Linus Torvalds
6fa425a265 for-5.2-rc4-tag
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Merge tag 'for-5.2-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fix from David Sterba:
 "One regression fix to TRIM ioctl.

  The range cannot be used as its meaning can be confusing regarding
  physical and logical addresses. This confusion in code led to
  potential corruptions when the range overlapped data.

  The original patch made it to several stable kernels and was promptly
  reverted, the version for master branch is different due to additional
  changes but the change is effectively the same"

* tag 'for-5.2-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: Always trim all unallocated space in btrfs_trim_free_extents
2019-06-11 15:10:15 -10:00
Nikolay Borisov
8103d10b71 btrfs: Always trim all unallocated space in btrfs_trim_free_extents
This patch removes support for range parameters of FITRIM ioctl when
trimming unallocated space on devices. This is necessary since ranges
passed from user space are generally interpreted as logical addresses,
whereas btrfs_trim_free_extents used to interpret them as device
physical extents. This could result in counter-intuitive behavior for
users so it's best to remove that support altogether.

Additionally, the existing range support had a bug where if an offset
was passed to FITRIM which overflows u64 e.g. -1 (parsed as u64
18446744073709551615) then wrong data was fed into btrfs_issue_discard,
which in turn leads to wrap-around when aligning the passed range and
results in wrong regions being discarded which leads to data corruption.

Fixes: c2d1b3aae3 ("btrfs: Honour FITRIM range constraints during free space trim")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-06-07 14:52:05 +02:00
Linus Torvalds
318adf8e4b for-5.2-rc2-tag
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Merge tag 'for-5.2-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "A few more fixes for bugs reported by users, fuzzing tools and
  regressions:

   - fix crashes in relocation:
       + resuming interrupted balance operation does not properly clean
         up orphan trees
       + with enabled qgroups, resuming needs to be more careful about
         block groups due to limited context when updating qgroups

   - fsync and logging fixes found by fuzzing

   - incremental send fixes for no-holes and clone

   - fix spin lock type used in timer function for zstd"

* tag 'for-5.2-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  Btrfs: fix race updating log root item during fsync
  Btrfs: fix wrong ctime and mtime of a directory after log replay
  Btrfs: fix fsync not persisting changed attributes of a directory
  btrfs: qgroup: Check bg while resuming relocation to avoid NULL pointer dereference
  btrfs: reloc: Also queue orphan reloc tree for cleanup to avoid BUG_ON()
  Btrfs: incremental send, fix emission of invalid clone operations
  Btrfs: incremental send, fix file corruption when no-holes feature is enabled
  btrfs: correct zstd workspace manager lock to use spin_lock_bh()
  btrfs: Ensure replaced device doesn't have pending chunk allocation
2019-05-30 20:52:40 -07:00
Filipe Manana
06989c799f Btrfs: fix race updating log root item during fsync
When syncing the log, the final phase of a fsync operation, we need to
either create a log root's item or update the existing item in the log
tree of log roots, and that depends on the current value of the log
root's log_transid - if it's 1 we need to create the log root item,
otherwise it must exist already and we update it. Since there is no
synchronization between updating the log_transid and checking it for
deciding whether the log root's item needs to be created or updated, we
end up with a tiny race window that results in attempts to update the
item to fail because the item was not yet created:

              CPU 1                                    CPU 2

  btrfs_sync_log()

    lock root->log_mutex

    set log root's log_transid to 1

    unlock root->log_mutex

                                               btrfs_sync_log()

                                                 lock root->log_mutex

                                                 sets log root's
                                                 log_transid to 2

                                                 unlock root->log_mutex

    update_log_root()

      sees log root's log_transid
      with a value of 2

        calls btrfs_update_root(),
        which fails with -EUCLEAN
        and causes transaction abort

Until recently the race lead to a BUG_ON at btrfs_update_root(), but after
the recent commit 7ac1e464c4 ("btrfs: Don't panic when we can't find a
root key") we just abort the current transaction.

A sample trace of the BUG_ON() on a SLE12 kernel:

  ------------[ cut here ]------------
  kernel BUG at ../fs/btrfs/root-tree.c:157!
  Oops: Exception in kernel mode, sig: 5 [#1]
  SMP NR_CPUS=2048 NUMA pSeries
  (...)
  Supported: Yes, External
  CPU: 78 PID: 76303 Comm: rtas_errd Tainted: G                 X 4.4.156-94.57-default #1
  task: c00000ffa906d010 ti: c00000ff42b08000 task.ti: c00000ff42b08000
  NIP: d000000036ae5cdc LR: d000000036ae5cd8 CTR: 0000000000000000
  REGS: c00000ff42b0b860 TRAP: 0700   Tainted: G                 X  (4.4.156-94.57-default)
  MSR: 8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE>  CR: 22444484  XER: 20000000
  CFAR: d000000036aba66c SOFTE: 1
  GPR00: d000000036ae5cd8 c00000ff42b0bae0 d000000036bda220 0000000000000054
  GPR04: 0000000000000001 0000000000000000 c00007ffff8d37c8 0000000000000000
  GPR08: c000000000e19c00 0000000000000000 0000000000000000 3736343438312079
  GPR12: 3930373337303434 c000000007a3a800 00000000007fffff 0000000000000023
  GPR16: c00000ffa9d26028 c00000ffa9d261f8 0000000000000010 c00000ffa9d2ab28
  GPR20: c00000ff42b0bc48 0000000000000001 c00000ff9f0d9888 0000000000000001
  GPR24: c00000ffa9d26000 c00000ffa9d261e8 c00000ffa9d2a800 c00000ff9f0d9888
  GPR28: c00000ffa9d26028 c00000ffa9d2aa98 0000000000000001 c00000ffa98f5b20
  NIP [d000000036ae5cdc] btrfs_update_root+0x25c/0x4e0 [btrfs]
  LR [d000000036ae5cd8] btrfs_update_root+0x258/0x4e0 [btrfs]
  Call Trace:
  [c00000ff42b0bae0] [d000000036ae5cd8] btrfs_update_root+0x258/0x4e0 [btrfs] (unreliable)
  [c00000ff42b0bba0] [d000000036b53610] btrfs_sync_log+0x2d0/0xc60 [btrfs]
  [c00000ff42b0bce0] [d000000036b1785c] btrfs_sync_file+0x44c/0x4e0 [btrfs]
  [c00000ff42b0bd80] [c00000000032e300] vfs_fsync_range+0x70/0x120
  [c00000ff42b0bdd0] [c00000000032e44c] do_fsync+0x5c/0xb0
  [c00000ff42b0be10] [c00000000032e8dc] SyS_fdatasync+0x2c/0x40
  [c00000ff42b0be30] [c000000000009488] system_call+0x3c/0x100
  Instruction dump:
  7f43d378 4bffebb9 60000000 88d90008 3d220000 e8b90000 3b390009 e87a01f0
  e8898e08 e8f90000 4bfd48e5 60000000 <0fe00000> e95b0060 39200004 394a0ea0
  ---[ end trace 8f2dc8f919cabab8 ]---

So fix this by doing the check of log_transid and updating or creating the
log root's item while holding the root's log_mutex.

Fixes: 7237f18336 ("Btrfs: fix tree logs parallel sync")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-05-28 19:26:46 +02:00
Filipe Manana
5338e43abb Btrfs: fix wrong ctime and mtime of a directory after log replay
When replaying a log that contains a new file or directory name that needs
to be added to its parent directory, we end up updating the mtime and the
ctime of the parent directory to the current time after we have set their
values to the correct ones (set at fsync time), efectivelly losing them.

Sample reproducer:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt

  $ mkdir /mnt/dir
  $ touch /mnt/dir/file

  # fsync of the directory is optional, not needed
  $ xfs_io -c fsync /mnt/dir
  $ xfs_io -c fsync /mnt/dir/file

  $ stat -c %Y /mnt/dir
  1557856079

  <power failure>

  $ sleep 3
  $ mount /dev/sdb /mnt
  $ stat -c %Y /mnt/dir
  1557856082

    --> should have been 1557856079, the mtime is updated to the current
        time when replaying the log

Fix this by not updating the mtime and ctime to the current time at
btrfs_add_link() when we are replaying a log tree.

This could be triggered by my recent fsync fuzz tester for fstests, for
which an fstests patch exists titled "fstests: generic, fsync fuzz tester
with fsstress".

Fixes: e02119d5a7 ("Btrfs: Add a write ahead tree log to optimize synchronous operations")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-05-28 19:16:16 +02:00
Filipe Manana
60d9f50308 Btrfs: fix fsync not persisting changed attributes of a directory
While logging an inode we follow its ancestors and for each one we mark
it as logged in the current transaction, even if we have not logged it.
As a consequence if we change an attribute of an ancestor, such as the
UID or GID for example, and then explicitly fsync it, we end up not
logging the inode at all despite returning success to user space, which
results in the attribute being lost if a power failure happens after
the fsync.

Sample reproducer:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt

  $ mkdir /mnt/dir
  $ chown 6007:6007 /mnt/dir

  $ sync

  $ chown 9003:9003 /mnt/dir
  $ touch /mnt/dir/file
  $ xfs_io -c fsync /mnt/dir/file

  # fsync our directory after fsync'ing the new file, should persist the
  # new values for the uid and gid.
  $ xfs_io -c fsync /mnt/dir

  <power failure>

  $ mount /dev/sdb /mnt
  $ stat -c %u:%g /mnt/dir
  6007:6007

    --> should be 9003:9003, the uid and gid were not persisted, despite
        the explicit fsync on the directory prior to the power failure

Fix this by not updating the logged_trans field of ancestor inodes when
logging an inode, since we have not logged them. Let only future calls to
btrfs_log_inode() to mark inodes as logged.

This could be triggered by my recent fsync fuzz tester for fstests, for
which an fstests patch exists titled "fstests: generic, fsync fuzz tester
with fsstress".

Fixes: 12fcfd22fe ("Btrfs: tree logging unlink/rename fixes")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-05-28 18:56:50 +02:00
Qu Wenruo
57949d033a btrfs: qgroup: Check bg while resuming relocation to avoid NULL pointer dereference
[BUG]
When mounting a fs with reloc tree and has qgroup enabled, it can cause
NULL pointer dereference at mount time:

  BUG: kernel NULL pointer dereference, address: 00000000000000a8
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEMPT SMP NOPTI
  RIP: 0010:btrfs_qgroup_add_swapped_blocks+0x186/0x300 [btrfs]
  Call Trace:
   replace_path.isra.23+0x685/0x900 [btrfs]
   merge_reloc_root+0x26e/0x5f0 [btrfs]
   merge_reloc_roots+0x10a/0x1a0 [btrfs]
   btrfs_recover_relocation+0x3cd/0x420 [btrfs]
   open_ctree+0x1bc8/0x1ed0 [btrfs]
   btrfs_mount_root+0x544/0x680 [btrfs]
   legacy_get_tree+0x34/0x60
   vfs_get_tree+0x2d/0xf0
   fc_mount+0x12/0x40
   vfs_kern_mount.part.12+0x61/0xa0
   vfs_kern_mount+0x13/0x20
   btrfs_mount+0x16f/0x860 [btrfs]
   legacy_get_tree+0x34/0x60
   vfs_get_tree+0x2d/0xf0
   do_mount+0x81f/0xac0
   ksys_mount+0xbf/0xe0
   __x64_sys_mount+0x25/0x30
   do_syscall_64+0x65/0x240
   entry_SYSCALL_64_after_hwframe+0x49/0xbe

[CAUSE]
In btrfs_recover_relocation(), we don't have enough info to determine
which block group we're relocating, but only to merge existing reloc
trees.

Thus in btrfs_recover_relocation(), rc->block_group is NULL.
btrfs_qgroup_add_swapped_blocks() hasn't taken this into consideration,
and causes a NULL pointer dereference.

The bug is introduced by commit 3d0174f78e ("btrfs: qgroup: Only trace
data extents in leaves if we're relocating data block group"), and
later qgroup refactoring still keeps this optimization.

[FIX]
Thankfully in the context of btrfs_recover_relocation(), there is no
other progress can modify tree blocks, thus those swapped tree blocks
pair will never affect qgroup numbers, no matter whatever we set for
block->trace_leaf.

So we only need to check if @bg is NULL before accessing @bg->flags.

Reported-by: Juan Erbes <jerbes@gmail.com>
Link: https://bugzilla.opensuse.org/show_bug.cgi?id=1134806
Fixes: 3d0174f78e ("btrfs: qgroup: Only trace data extents in leaves if we're relocating data block group")
CC: stable@vger.kernel.org # 4.20+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-05-28 18:54:10 +02:00
Qu Wenruo
30d40577e3 btrfs: reloc: Also queue orphan reloc tree for cleanup to avoid BUG_ON()
[BUG]
When a fs has orphan reloc tree along with unfinished balance:
  ...
        item 16 key (TREE_RELOC ROOT_ITEM FS_TREE) itemoff 12090 itemsize 439
                generation 12 root_dirid 256 bytenr 300400640 level 1 refs 0 <<<
                lastsnap 8 byte_limit 0 bytes_used 1359872 flags 0x0(none)
                uuid 7c48d938-33a3-4aae-ab19-6e5c9d406e46
        item 17 key (BALANCE TEMPORARY_ITEM 0) itemoff 11642 itemsize 448
                temporary item objectid BALANCE offset 0
                balance status flags 14

Then at mount time, we can hit the following kernel BUG_ON():
  BTRFS info (device dm-3): relocating block group 298844160 flags metadata|dup
  ------------[ cut here ]------------
  kernel BUG at fs/btrfs/relocation.c:1413!
  invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
  CPU: 1 PID: 897 Comm: btrfs-balance Tainted: G           O      5.2.0-rc1-custom #15
  RIP: 0010:create_reloc_root+0x1eb/0x200 [btrfs]
  Call Trace:
   btrfs_init_reloc_root+0x96/0xb0 [btrfs]
   record_root_in_trans+0xb2/0xe0 [btrfs]
   btrfs_record_root_in_trans+0x55/0x70 [btrfs]
   select_reloc_root+0x7e/0x230 [btrfs]
   do_relocation+0xc4/0x620 [btrfs]
   relocate_tree_blocks+0x592/0x6a0 [btrfs]
   relocate_block_group+0x47b/0x5d0 [btrfs]
   btrfs_relocate_block_group+0x183/0x2f0 [btrfs]
   btrfs_relocate_chunk+0x4e/0xe0 [btrfs]
   btrfs_balance+0x864/0xfa0 [btrfs]
   balance_kthread+0x3b/0x50 [btrfs]
   kthread+0x123/0x140
   ret_from_fork+0x27/0x50

[CAUSE]
In btrfs, reloc trees are used to record swapped tree blocks during
balance.
Reloc tree either get merged (replace old tree blocks of its parent
subvolume) in next transaction if its ref is 1 (fresh).
Or is already merged and will be cleaned up if its ref is 0 (orphan).

After commit d2311e6985 ("btrfs: relocation: Delay reloc tree deletion
after merge_reloc_roots"), reloc tree cleanup is delayed until one block
group is balanced.

Since fresh reloc roots are recorded during merge, as long as there
is no power loss, those orphan reloc roots converted from fresh ones are
handled without problem.

However when power loss happens, orphan reloc roots can be recorded
on-disk, thus at next mount time, we will have orphan reloc roots from
on-disk data directly, and ignored by clean_dirty_subvols() routine.

Then when background balance starts to balance another block group, and
needs to create new reloc root for the same root, btrfs_insert_item()
returns -EEXIST, and trigger that BUG_ON().

[FIX]
For orphan reloc roots, also queue them to rc->dirty_subvol_roots, so
all reloc roots no matter orphan or not, can be cleaned up properly and
avoid above BUG_ON().

And to cooperate with above change, clean_dirty_subvols() will check if
the queued root is a reloc root or a subvol root.
For a subvol root, do the old work, and for a orphan reloc root, clean it
up.

Fixes: d2311e6985 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots")
CC: stable@vger.kernel.org # 5.1
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-05-28 18:54:10 +02:00
Filipe Manana
3c850b4511 Btrfs: incremental send, fix emission of invalid clone operations
When doing an incremental send we can now issue clone operations with a
source range that ends at the source's file eof and with a destination
range that ends at an offset smaller then the destination's file eof.
If the eof of the source file is not aligned to the sector size of the
filesystem, the receiver will get a -EINVAL error when trying to do the
operation or, on older kernels, silently corrupt the destination file.
The corruption happens on kernels without commit ac765f83f1
("Btrfs: fix data corruption due to cloning of eof block"), while the
failure to clone happens on kernels with that commit.

Example reproducer:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt/sdb

  $ xfs_io -f -c "pwrite -S 0xb1 0 2M" /mnt/sdb/foo
  $ xfs_io -f -c "pwrite -S 0xc7 0 2M" /mnt/sdb/bar
  $ xfs_io -f -c "pwrite -S 0x4d 0 2M" /mnt/sdb/baz
  $ xfs_io -f -c "pwrite -S 0xe2 0 2M" /mnt/sdb/zoo

  $ btrfs subvolume snapshot -r /mnt/sdb /mnt/sdb/base

  $ btrfs send -f /tmp/base.send /mnt/sdb/base

  $ xfs_io -c "reflink /mnt/sdb/bar 1560K 500K 100K" /mnt/sdb/bar
  $ xfs_io -c "reflink /mnt/sdb/bar 1560K 0 100K" /mnt/sdb/zoo
  $ xfs_io -c "truncate 550K" /mnt/sdb/bar

  $ btrfs subvolume snapshot -r /mnt/sdb /mnt/sdb/incr

  $ btrfs send -f /tmp/incr.send -p /mnt/sdb/base /mnt/sdb/incr

  $ mkfs.btrfs -f /dev/sdc
  $ mount /dev/sdc /mnt/sdc

  $ btrfs receive -f /tmp/base.send /mnt/sdc
  $ btrfs receive -vv -f /tmp/incr.send /mnt/sdc
  (...)
  truncate bar size=563200
  utimes bar
  clone zoo - source=bar source offset=512000 offset=0 length=51200
  ERROR: failed to clone extents to zoo
  Invalid argument

The failure happens because the clone source range ends at the eof of file
bar, 563200, which is not aligned to the filesystems sector size (4Kb in
this case), and the destination range ends at offset 0 + 51200, which is
less then the size of the file zoo (2Mb).

So fix this by detecting such case and instead of issuing a clone
operation for the whole range, do a clone operation for smaller range
that is sector size aligned followed by a write operation for the block
containing the eof. Here we will always be pessimistic and assume the
destination filesystem of the send stream has the largest possible sector
size (64Kb), since we have no way of determining it.

This fixes a recent regression introduced in kernel 5.2-rc1.

Fixes: 040ee6120c ("Btrfs: send, improve clone range")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-05-28 18:54:10 +02:00