[PATCH v2 1/7] ceph: Do not look at the index of an encrypted page

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

If the pages array contains encrypted pages, we cannot look at
page->index because that field is uninitialised.  Instead, use the new
ceph_fscrypt_pagecache_folio() to get the pagecache folio and look at
the index of that.

Fixes: d55207717ded (ceph: add encryption support to writepage and writepages)
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
---
 fs/ceph/addr.c   | 5 ++++-
 fs/ceph/crypto.h | 7 +++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index f5224a566b69..80bc0cbacd7a 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -1356,8 +1356,11 @@ static int ceph_writepages_start(struct address_space *mapping,
 			memset(data_pages + i, 0,
 			       locked_pages * sizeof(*pages));
 		} else {
+			struct folio *folio;
+
 			BUG_ON(num_ops != req->r_num_ops);
-			index = pages[i - 1]->index + 1;
+			folio = ceph_fscrypt_pagecache_folio(pages[i - 1]);
+			index = folio->index + 1;
 			/* request message now owns the pages array */
 			pages = NULL;
 		}
diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h
index d0768239a1c9..e4404ef589a1 100644
--- a/fs/ceph/crypto.h
+++ b/fs/ceph/crypto.h
@@ -280,6 +280,13 @@ static inline struct page *ceph_fscrypt_pagecache_page(struct page *page)
 }
 #endif /* CONFIG_FS_ENCRYPTION */
 
+static inline struct folio *ceph_fscrypt_pagecache_folio(struct page *page)
+{
+	if (fscrypt_is_bounce_page(page))
+		page = fscrypt_pagecache_page(page);
+	return page_folio(page);
+}
+
 static inline loff_t ceph_fscrypt_page_offset(struct page *page)
 {
 	return page_offset(ceph_fscrypt_pagecache_page(page));
-- 
2.47.2