[PATCH 6.18 099/396] netfs: handle single writeback rolling buffer allocation failure

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Yichong Chen <[email protected]>

[ Upstream commit 37a1c535c80c67d98668d190c7432f9ebda43310 ]

netfs_write_folio_single() takes an extra folio reference before
appending the folio to the rolling buffer.

rolling_buffer_append() can fail if it cannot allocate another
folio_queue. Check the return value and drop the extra folio reference
before returning the error.

Fixes: 49866ce7ea8d ("netfs: Add support for caching single monolithic objects such as AFS dirs")
Signed-off-by: Yichong Chen <[email protected]>
Signed-off-by: David Howells <[email protected]>
Link: https://patch.msgid.link/[email protected]
cc: Paulo Alcantara <[email protected]>
cc: [email protected]
cc: [email protected]
Signed-off-by: Christian Brauner (Amutable) <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
 fs/netfs/write_issue.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c
index 76614339554ea..5f216907b1e50 100644
--- a/fs/netfs/write_issue.c
+++ b/fs/netfs/write_issue.c
@@ -730,6 +730,7 @@ static int netfs_write_folio_single(struct netfs_io_request *wreq,
 	size_t iter_off = 0;
 	size_t fsize = folio_size(folio), flen;
 	loff_t fpos = folio_pos(folio);
+	ssize_t ret;
 	bool to_eof = false;
 	bool no_debug = false;
 
@@ -758,7 +759,11 @@ static int netfs_write_folio_single(struct netfs_io_request *wreq,
 
 	/* Attach the folio to the rolling buffer. */
 	folio_get(folio);
-	rolling_buffer_append(&wreq->buffer, folio, NETFS_ROLLBUF_PUT_MARK);
+	ret = rolling_buffer_append(&wreq->buffer, folio, NETFS_ROLLBUF_PUT_MARK);
+	if (ret < 0) {
+		folio_put(folio);
+		return ret;
+	}
 
 	/* Move the submission point forward to allow for write-streaming data
 	 * not starting at the front of the page.  We don't do write-streaming
-- 
2.53.0