diff options
| author | Omar Sandoval <osandov@fb.com> | 2019-08-15 14:04:02 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-01-27 14:46:46 +0100 |
| commit | a7a67b4e8e8d68d6301d233645a3bfbfba40bc35 (patch) | |
| tree | b752a1392a3ba829f88df0489cef618627cf9b18 /fs | |
| parent | 510cd98350463b841fdc01065eac4cec180ba9d5 (diff) | |
btrfs: use correct count in btrfs_file_write_iter()
[ Upstream commit c09767a8960ca0500fb636bf73686723337debf4 ]
generic_write_checks() may modify iov_iter_count(), so we must get the
count after the call, not before. Using the wrong one has a couple of
consequences:
1. We check a longer range in check_can_nocow() for nowait than we're
actually writing.
2. We create extra hole extent maps in btrfs_cont_expand(). As far as I
can tell, this is harmless, but I might be missing something.
These issues are pretty minor, but let's fix it before something more
important trips on it.
Fixes: edf064e7c6fe ("btrfs: nowait aio support")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/file.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 97be32da857a..c68ce3412dc1 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1882,7 +1882,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host); ssize_t err; loff_t pos; - size_t count = iov_iter_count(from); + size_t count; loff_t oldsize; int clean_page = 0; @@ -1904,6 +1904,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, } pos = iocb->ki_pos; + count = iov_iter_count(from); if (iocb->ki_flags & IOCB_NOWAIT) { /* * We will allocate space in case nodatacow is not set, |