[PATCH 5.18 0935/1095] cifs: Fix memory leak when using fscache

Greg Kroah-Hartman
2022-08-15T22:59:05Z

From: Matthew Wilcox (Oracle) <willy@infradead.org>

[ Upstream commit c6f62f81b488d00afaa86bae26c6ce9ab12c709e ]

If we hit the 'index == next_cached' case, we leak a refcount on the
struct page. Fix this by using readahead_folio() which takes care of
the refcount for you.

Fixes: 0174ee9947bd ("cifs: Implement cache I/O by accessing the cache directly")
Cc: David Howells <dhowells@redhat.com>
Cc: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cifs/file.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 58dce567ceaf..3d475f1847a4 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -4456,10 +4456,10 @@ static void cifs_readahead(struct readahead_control *ractl)
* TODO: Send a whole batch of pages to be read
* by the cache.
*/
- page = readahead_page(ractl);
- last_batch_size = 1 << thp_order(page);
+ struct folio *folio = readahead_folio(ractl);
+ last_batch_size = folio_nr_pages(folio);
if (cifs_readpage_from_fscache(ractl->mapping->host,
- page) < 0) {
+ &folio->page) < 0) {
/*
* TODO: Deal with cache read failure
* here, but for the moment, delegate
@@ -4467,7 +4467,7 @@ static void cifs_readahead(struct readahead_control *ractl)
*/
caching = false;
}
- unlock_page(page);
+ folio_unlock(folio);
next_cached++;
cache_nr_pages--;
if (cache_nr_pages == 0)
--
2.35.1