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/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index c4893e2..1a09104 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -259,7 +259,11 @@
trace_xfs_file_buffered_read(ip, iov_iter_count(to), iocb->ki_pos);
- xfs_ilock(ip, XFS_IOLOCK_SHARED);
+ if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED)) {
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EAGAIN;
+ xfs_ilock(ip, XFS_IOLOCK_SHARED);
+ }
ret = generic_file_read_iter(iocb, to);
xfs_iunlock(ip, XFS_IOLOCK_SHARED);
@@ -636,6 +640,9 @@
int enospc = 0;
int iolock;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
write_retry:
iolock = XFS_IOLOCK_EXCL;
xfs_ilock(ip, iolock);
@@ -912,7 +919,7 @@
return -EFBIG;
if (XFS_FORCED_SHUTDOWN(XFS_M(inode->i_sb)))
return -EIO;
- file->f_mode |= FMODE_AIO_NOWAIT;
+ file->f_mode |= FMODE_NOWAIT;
return 0;
}