[PATCH v3 4/9] vfs: Copy should check len after file open mode

[Anna Schumaker <Anna.Schumaker@netapp.com>]

I don't think it makes sense to report that a copy succeeded if the
files aren't open properly.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Reviewed-by: David Sterba <dsterba@suse.com>
---
 fs/read_write.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index dd10750..f3d6c48 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1345,9 +1345,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (flags)
 		return -EINVAL;
 
-	if (len == 0)
-		return 0;
-
 	/* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT  */
 	ret = rw_verify_area(READ, file_in, &pos_in, len);
 	if (ret >= 0)
@@ -1378,6 +1375,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (inode_in == inode_out)
 		return -EINVAL;
 
+	if (len == 0)
+		return 0;
+
 	ret = mnt_want_write_file(file_out);
 	if (ret)
 		return ret;
-- 
2.5.3