[PATCH 3/4] netfs: release readahead folios on iterator preparation failure

[David Howells <dhowells@redhat.com>]

From: Yichong Chen <chenyichong@uniontech.com>

netfs_prepare_read_iterator() batches readahead folios in put_batch so that
the folio references can be dropped after the I/O iterator has been
prepared.

If rolling_buffer_load_from_ra() fails after earlier folios have been
batched, the function returns immediately and leaves those references held.
Release the batch before returning the error.

Fixes: 06fa229ceb36 ("netfs: Abstract out a rolling folio buffer implementation")
Signed-off-by: Yichong Chen <chenyichong@uniontech.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
---
 fs/netfs/buffered_read.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c
index 24a8a5418e31..3d86414ee40f 100644
--- a/fs/netfs/buffered_read.c
+++ b/fs/netfs/buffered_read.c
@@ -102,8 +102,10 @@ static ssize_t netfs_prepare_read_iterator(struct netfs_io_subrequest *subreq,
 
 			added = rolling_buffer_load_from_ra(&rreq->buffer, ractl,
 							    &put_batch);
-			if (added < 0)
+			if (added < 0) {
+				folio_batch_release(&put_batch);
 				return added;
+			}
 			rreq->submitted += added;
 		}
 		folio_batch_release(&put_batch);