linux-kernel - [PATCH] splice: fix bad unlock

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Date:	Fri, 20 Jul 2007 15:18:12 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] splice: fix bad unlock_page() in error case

Hi,

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@...cle.com>
using fio.

Signed-off-by: Jens Axboe <jens.axboe@...cle.com>

diff --git a/fs/splice.c b/fs/splice.c
index 099b831..4960085 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -628,7 +628,7 @@ 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);
@@ -684,8 +684,9 @@ find_page:
 	 */
 	mark_page_accessed(page);
 out:
-	page_cache_release(page);
 	unlock_page(page);
+out_release:
+	page_cache_release(page);
 out_ret:
 	return ret;
 }

-- 
Jens Axboe

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