From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Assigning pos for usage early messes up in append mode, where
the pos is re-assigned in generic_write_checks(). Assign
pos later to get the correct position to write from iocb->ki_pos.
Since check_can_nocow also uses the value of pos, we shift
generic_write_checks() before check_can_nocow(). Checks with
IOCB_DIRECT are present in generic_write_checks(), so checking
for IOCB_NOWAIT is enough.
Also, put locking sequence in the fast path.
Changes since v1:
- Moved pos higher up to encompass check_can_nocow() call.
Fixes: edf064e7c6fe ("btrfs: nowait aio support")
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
fs/btrfs/file.c | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 59e2dccdf75b..ad53832838b5 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1875,16 +1875,25 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
ssize_t num_written = 0;
bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host);
ssize_t err;
- loff_t pos = iocb->ki_pos;
+ loff_t pos;
size_t count = iov_iter_count(from);
loff_t oldsize;
int clean_page = 0;
- if ((iocb->ki_flags & IOCB_NOWAIT) &&
- (iocb->ki_flags & IOCB_DIRECT)) {
- /* Don't sleep on inode rwsem */
- if (!inode_trylock(inode))
+ if (!inode_trylock(inode)) {
+ if (iocb->ki_flags & IOCB_NOWAIT)
return -EAGAIN;
+ inode_lock(inode);
+ }
+
+ err = generic_write_checks(iocb, from);
+ if (err <= 0) {
+ inode_unlock(inode);
+ return err;
+ }
+
+ pos = iocb->ki_pos;
+ if (iocb->ki_flags & IOCB_NOWAIT) {
/*
* We will allocate space in case nodatacow is not set,
* so bail
@@ -1895,13 +1904,6 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
inode_unlock(inode);
return -EAGAIN;
}
- } else
- inode_lock(inode);
-
- err = generic_write_checks(iocb, from);
- if (err <= 0) {
- inode_unlock(inode);
- return err;
}
current->backing_dev_info = inode_to_bdi(inode);
--
2.12.0
