[PATCH 1/2] netfs: Fix i_dio_count leak on DIO read past i_size

[David Howells]

From: Marc Dionne <marc.dionne@xxxxxxxxxxxx>

If netfs_begin_read gets a NETFS_DIO_READ request that begins
past i_size, it won't perform any i/o and just return 0.  This
will leak an increment to i_dio_count that is done at the top
of the function.

This can cause subsequent buffered read requests to block
indefinitely, waiting for a non existing dio operation to complete.

Add a inode_dio_end() for the NETFS_DIO_READ case, before returning.

Signed-off-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Jeff Layton <jlayton@xxxxxxxxxx>
cc: linux-afs@xxxxxxxxxxxxxxxxxxx
cc: netfs@xxxxxxxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
---
 fs/netfs/io.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/netfs/io.c b/fs/netfs/io.c
index e8ff1e61ce79..4261ad6c55b6 100644
--- a/fs/netfs/io.c
+++ b/fs/netfs/io.c
@@ -748,6 +748,8 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync)
 
 	if (!rreq->submitted) {
 		netfs_put_request(rreq, false, netfs_rreq_trace_put_no_submit);
+		if (rreq->origin == NETFS_DIO_READ)
+			inode_dio_end(rreq->inode);
 		ret = 0;
 		goto out;
 	}