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| author | Filipe Manana <fdmanana@suse.com> | 2022-03-15 15:22:36 +0000 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2022-05-16 17:03:09 +0200 |
| commit | 831e1ee60216534c54f2e240f9586d6cfe29b1c2 (patch) | |
| tree | b09d3c34a9c16abde410cf6b5da7eb2f638be6a1 /fs/btrfs/file.c | |
| parent | 47e1d1c7bb35ccf1d327ddcfaf59b268c8770159 (diff) | |
| download | lwn-831e1ee60216534c54f2e240f9586d6cfe29b1c2.tar.gz lwn-831e1ee60216534c54f2e240f9586d6cfe29b1c2.zip | |
btrfs: remove useless dio wait call when doing fallocate zero range
When starting a fallocate zero range operation, before getting the first
extent map for the range, we make a call to inode_dio_wait().
This logic was needed in the past because direct IO writes within the
i_size boundary did not take the inode's VFS lock. This was because that
lock used to be a mutex, then some years ago it was switched to a rw
semaphore (by commit 9902af79c01a8e ("parallel lookups: actual switch to
rwsem")), and then btrfs was changed to take the VFS inode's lock in
shared mode for writes that don't cross the i_size boundary (done in
commit e9adabb9712ef9 ("btrfs: use shared lock for direct writes within
EOF")). The lockless direct IO writes could result in a race with the
zero range operation, resulting in the later getting a stale extent
map for the range.
So remove this no longer needed call to inode_dio_wait(), as fallocate
takes the inode's VFS lock in exclusive mode and direct IO writes within
i_size take that same lock in shared mode.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/file.c')
| -rw-r--r-- | fs/btrfs/file.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index fa7bbcab1a6a..bd638cbb5bda 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -3237,8 +3237,6 @@ static int btrfs_zero_range(struct inode *inode, u64 bytes_to_reserve = 0; bool space_reserved = false; - inode_dio_wait(inode); - em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, alloc_start, alloc_end - alloc_start); if (IS_ERR(em)) { |