fs: support RWF_NOWAIT for buffered reads
This is based on the old idea and code from Milosz Tanski. With the aio
nowait code it becomes mostly trivial now. Buffered writes continue to
return -EOPNOTSUPP if RWF_NOWAIT is passed.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 9e75d8a..e62dd55 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1886,6 +1886,10 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
loff_t oldsize;
int clean_page = 0;
+ if (!(iocb->ki_flags & IOCB_DIRECT) &&
+ (iocb->ki_flags & IOCB_NOWAIT))
+ return -EOPNOTSUPP;
+
if (!inode_trylock(inode)) {
if (iocb->ki_flags & IOCB_NOWAIT)
return -EAGAIN;
@@ -3105,7 +3109,7 @@ static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int whence)
static int btrfs_file_open(struct inode *inode, struct file *filp)
{
- filp->f_mode |= FMODE_AIO_NOWAIT;
+ filp->f_mode |= FMODE_NOWAIT;
return generic_file_open(inode, filp);
}