From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Return EAGAIN if any of the following checks fail for direct I/O:
+ i_rwsem is lockable
+ Writing beyond end of file (will trigger allocation)
+ Blocks are not allocated at the write location
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
---
fs/ext4/file.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 02ce7e7bbdf5..25cd42baadea 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -216,7 +216,13 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
return ext4_dax_write_iter(iocb, from);
#endif
- inode_lock(inode);
+ if (iocb->ki_flags & IOCB_NOWAIT) {
+ if (!inode_trylock(inode))
+ return -EAGAIN;
+ } else {
+ inode_lock(inode);
+ }
+
ret = ext4_write_checks(iocb, from);
if (ret <= 0)
goto out;
@@ -235,9 +241,15 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
iocb->private = &overwrite;
/* Check whether we do a DIO overwrite or not */
- if (o_direct && ext4_should_dioread_nolock(inode) && !unaligned_aio &&
- ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from)))
- overwrite = 1;
+ if (o_direct && !unaligned_aio) {
+ if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) {
+ if (ext4_should_dioread_nolock(inode))
+ overwrite = 1;
+ } else if (iocb->ki_flags & IOCB_NOWAIT) {
+ ret = -EAGAIN;
+ goto out;
+ }
+ }
ret = __generic_file_write_iter(iocb, from);
inode_unlock(inode);
@@ -435,6 +447,10 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
if (ret < 0)
return ret;
}
+
+ /* Set the flags to support nowait AIO */
+ filp->f_mode |= FMODE_AIO_NOWAIT;
+
return dquot_file_open(inode, filp);
}
--
2.12.0
