diff options
| author |   Naohiro Aota <naohiro.aota@wdc.com> | 2022-03-29 15:56:00 +0900 |
|---|---|---|
| committer |   David Sterba <dsterba@suse.com> | 2022-05-16 17:03:10 +0200 |
| commit | 0320b3538b2b819c24daa699a26aa184f3d3cc6c (patch) | |
| tree | 5eacf6d28a3167b16dcde194cc7b82714a4f06b6 | |
| parent | fs: add a lockdep check function for sb_start_write() (diff) | |
| download | linux-dev-0320b3538b2b819c24daa699a26aa184f3d3cc6c.tar.xz linux-dev-0320b3538b2b819c24daa699a26aa184f3d3cc6c.zip | |
btrfs: assert that relocation is protected with sb_start_write()
Relocation of a data block group creates ordered extents. They can cause
a hang when a process is trying to thaw the filesystem.
We should have called sb_start_write(), so the filesystem is not being
frozen. Add an ASSERT to check it is protected.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
| -rw-r--r-- | fs/btrfs/relocation.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index b1c36fc72ffa..79af494a316a 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -3978,6 +3978,17 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start) if (!bg) return -ENOENT; + /* + * Relocation of a data block group creates ordered extents. Without + * sb_start_write(), we can freeze the filesystem while unfinished + * ordered extents are left. Such ordered extents can cause a deadlock + * e.g. when syncfs() is waiting for their completion but they can't + * finish because they block when joining a transaction, due to the + * fact that the freeze locks are being held in write mode. + */ + if (bg->flags & BTRFS_BLOCK_GROUP_DATA) + ASSERT(sb_write_started(fs_info->sb)); + if (btrfs_pinned_by_swapfile(fs_info, bg)) { btrfs_put_block_group(bg); return -ETXTBSY; |