[PATCH] CIFS: Fix readpages retrying on reconnects

* [PATCH] CIFS: Fix readpages retrying on reconnects
@ 2014-10-02 16:13 Pavel Shilovsky
       [not found] ` <1412266416-9172-1-git-send-email-piastry-7qunaywFIewox3rIn2DAYQ@public.gmane.org>
  0 siblings, 1 reply; 3+ messages in thread
From: Pavel Shilovsky @ 2014-10-02 16:13 UTC (permalink / raw)
  To: linux-cifs-u79uwXL29TY76Z2rM5mHXA; +Cc: Pavel Shilovsky

From: Pavel Shilovsky <pshilovsky-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>

If we got a reconnect error from async readv we re-add pages back
to page_list and continue loop. That is wrong because these pages
have been already added to the pagecache but page_list has pages that
have not been added to the pagecache yet. This ends up with a general
protection fault in put_pages after readpages. Fix it by not retrying
the read of these pages and falling back to readpage instead.

Signed-off-by: Pavel Shilovsky <pshilovsky-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>
---
 fs/cifs/file.c |    8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 7c018a1..5f29354 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3568,15 +3568,9 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
 				lru_cache_add_file(page);
 				unlock_page(page);
 				page_cache_release(page);
-				if (rc == -EAGAIN)
-					list_add_tail(&page->lru, &tmplist);
 			}
+			/* Fallback to the readpage in error/reconnect cases */
 			kref_put(&rdata->refcount, cifs_readdata_release);
-			if (rc == -EAGAIN) {
-				/* Re-add pages to the page_list and retry */
-				list_splice(&tmplist, page_list);
-				continue;
-			}
 			break;
 		}
 
-- 
1.7.10.4

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