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| author | Filipe Manana <fdmanana@suse.com> | 2020-06-15 20:48:58 +0300 |
|---|---|---|
| committer | Sasha Levin <sashal@kernel.org> | 2020-06-30 22:37:08 +0300 |
| commit | a79c3a99ac8187d79ce7cc6be8329454d2321ef5 (patch) | |
| tree | 4417f0aa966fda9231a1d2b05a09f17f5d049ffc | |
| parent | 863a197f7f102bfbd42f79b40c50947e9019f011 (diff) | |
| download | linux-a79c3a99ac8187d79ce7cc6be8329454d2321ef5.tar.xz | |
btrfs: fix failure of RWF_NOWAIT write into prealloc extent beyond eof
commit 4b1946284dd6641afdb9457101056d9e6ee6204c upstream.
If we attempt to write to prealloc extent located after eof using a
RWF_NOWAIT write, we always fail with -EAGAIN.
We do actually check if we have an allocated extent for the write at
the start of btrfs_file_write_iter() through a call to check_can_nocow(),
but later when we go into the actual direct IO write path we simply
return -EAGAIN if the write starts at or beyond EOF.
Trivial to reproduce:
$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt
$ touch /mnt/foo
$ chattr +C /mnt/foo
$ xfs_io -d -c "pwrite -S 0xab 0 64K" /mnt/foo
wrote 65536/65536 bytes at offset 0
64 KiB, 16 ops; 0.0004 sec (135.575 MiB/sec and 34707.1584 ops/sec)
$ xfs_io -c "falloc -k 64K 1M" /mnt/foo
$ xfs_io -d -c "pwrite -N -V 1 -S 0xfe -b 64K 64K 64K" /mnt/foo
pwrite: Resource temporarily unavailable
On xfs and ext4 the write succeeds, as expected.
Fix this by removing the wrong check at btrfs_direct_IO().
Fixes: edf064e7c6fec3 ("btrfs: nowait aio support")
CC: stable@vger.kernel.org # 4.14+
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>
| -rw-r--r-- | fs/btrfs/inode.c | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 0984601418e5..280c45c91ddc 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8857,9 +8857,6 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) dio_data.overwrite = 1; inode_unlock(inode); relock = true; - } else if (iocb->ki_flags & IOCB_NOWAIT) { - ret = -EAGAIN; - goto out; } ret = btrfs_delalloc_reserve_space(inode, &data_reserved, offset, count); |