From: Jens Axboe <jens.axboe@oracle.com>
Date: Fri, 20 Jul 2007 13:21:36 +0000 (+0200)
Subject: splice: fix double page unlock
X-Git-Tag: v2.6.22.2~52
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=36e1ed699210fd0173dfe0a8b2cde8a6b648ba3f;p=thirdparty%2Fkernel%2Fstable.git

splice: fix double page unlock

If add_to_page_cache_lru() fails, the page will not be locked. But
splice jumps to an error path that does a page release and unlock,
causing a BUG() in unlock_page().

Fix this by adding one more label that just releases the page. This bug
was actually triggered on EL5 by gurudas pai <gurudas.pai@oracle.com>
using fio.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/fs/splice.c b/fs/splice.c
index e7d7080de2f97..d3c6668bdbdd5 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -601,7 +601,7 @@ find_page:
 		ret = add_to_page_cache_lru(page, mapping, index,
 					    GFP_KERNEL);
 		if (unlikely(ret))
-			goto out;
+			goto out_release;
 	}
 
 	ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len);
@@ -657,8 +657,9 @@ find_page:
 	 */
 	mark_page_accessed(page);
 out:
-	page_cache_release(page);
 	unlock_page(page);
+out_release:
+	page_cache_release(page);
 out_ret:
 	return ret;
 }