From edf064e7c6fec3646b06c944a8e35d1a3de5c2c3 Mon Sep 17 00:00:00 2001
From: Goldwyn Rodrigues <rgoldwyn@suse.com>
Date: Tue, 20 Jun 2017 07:05:49 -0500
Subject: btrfs: nowait aio support

Return EAGAIN if any of the following checks fail
 + i_rwsem is not lockable
 + NODATACOW or PREALLOC is not set
 + Cannot nocow at the desired location
 + Writing beyond end of file which is not allocated

Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/btrfs/inode.c | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'fs/btrfs/inode.c')

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f942293dd7e7..556c93060606 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8754,6 +8754,9 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 			dio_data.overwrite = 1;
 			inode_unlock(inode);
 			relock = true;
+		} else if (iocb->ki_flags & IOCB_NOWAIT) {
+			ret = -EAGAIN;
+			goto out;
 		}
 		ret = btrfs_delalloc_reserve_space(inode, offset, count);
 		if (ret)
-- 
cgit