[PATCH 4.4 058/115] afs: Fix afs_kill_pages()

From: Greg Kroah-Hartman
Date: Mon Dec 18 2017 - 13:04:47 EST

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


From: David Howells <dhowells@xxxxxxxxxx>

[ Upstream commit 7286a35e893176169b09715096a4aca557e2ccd2 ]

Fix afs_kill_pages() in two ways:

(1) If a writeback has been partially flushed, then if we try and kill the
pages it contains, some of them may no longer be undergoing writeback
and end_page_writeback() will assert.

Fix this by checking to see whether the page in question is actually
undergoing writeback before ending that writeback.

(2) The loop that scans for pages to kill doesn't increase the first page
index, and so the loop may not terminate, but it will try to process
the same pages over and over again.

Fix this by increasing the first page index to one after the last page
we processed.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
fs/afs/write.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -299,10 +299,14 @@ static void afs_kill_pages(struct afs_vn
ASSERTCMP(pv.nr, ==, count);

for (loop = 0; loop < count; loop++) {
- ClearPageUptodate(pv.pages[loop]);
+ struct page *page = pv.pages[loop];
+ ClearPageUptodate(page);
if (error)
- SetPageError(pv.pages[loop]);
- end_page_writeback(pv.pages[loop]);
+ SetPageError(page);
+ if (PageWriteback(page))
+ end_page_writeback(page);
+ if (page->index >= first)
+ first = page->index + 1;