[2.6.20.17 review 18/58] splice: fix double page unlock

[Willy Tarreau <w@1wt.eu>]

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>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
 fs/splice.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/splice.c b/fs/splice.c
index 2fca6eb..b657217 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -614,7 +614,7 @@ find_page:
 			ret = add_to_page_cache_lru(page, mapping, index,
 						    GFP_KERNEL);
 			if (unlikely(ret))
-				goto out;
+				goto out_release;
 		}
 
 		/*
@@ -695,8 +695,9 @@ find_page:
 		goto find_page;
 	}
 out:
-	page_cache_release(page);
 	unlock_page(page);
+out_release:
+	page_cache_release(page);
 out_ret:
 	return ret;
 }
-- 
1.5.2.5

-- 
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