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authorOmar Sandoval <osandov@fb.com>2019-08-15 14:04:02 -0700
committerDavid Sterba <dsterba@suse.com>2019-09-09 14:59:17 +0200
commitc09767a8960ca0500fb636bf73686723337debf4 (patch)
tree7632ca4af900175285253b2f7b45057d8fe81738 /fs/btrfs/file.c
parentc82f823c9b006c31059341af41da9f8b2e3e64d9 (diff)
btrfs: use correct count in btrfs_file_write_iter()
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>
Diffstat (limited to 'fs/btrfs/file.c')
-rw-r--r--fs/btrfs/file.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 1cb694c96500..25df5b03b591 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1885,7 +1885,7 @@ 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;
@@ -1906,6 +1906,7 @@ 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,