linux-kernel - [PATCH 2/3] FS-Cache: Reduce cookie ref count if submit fails.

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Date:	Wed, 13 Aug 2014 12:58:21 -0400
From:	Milosz Tanski <milosz@...in.com>
To:	linux-cachefs@...hat.com
CC:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	David Howells <dhowells@...hat.com>, NeilBrown <neilb@...e.de>
Subject: [PATCH 2/3] FS-Cache: Reduce cookie ref count if submit fails.

I've been seeing issues with disposing cookies under vma pressure. The symptom
is that the refcount gets out of sync. In this case we fail to decrement the
refcount if submit fails. I found this while auditing the error in and around
cookie operations.

Signed-off-by: Milosz Tanski <milosz@...in.com>
---
 fs/fscache/object.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/fscache/object.c b/fs/fscache/object.c
index d3b4539..e1eb1f5 100644
--- a/fs/fscache/object.c
+++ b/fs/fscache/object.c
@@ -982,6 +982,8 @@ nomem:
 submit_op_failed:
 	clear_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags);
 	spin_unlock(&cookie->lock);
+	if (__fscache_unuse_cookie(cookie))
+		__fscache_wake_unused_cookie(cookie);
 	kfree(op);
 	_leave(" [EIO]");
 	return transit_to(KILL_OBJECT);
-- 
1.7.9.5


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