[PATCH 2.6.19-rc3] (1/2) fix bd_claim_by_kobject error handling

[PATCH 2.6.19-rc3] (1/2) fix bd_claim_by_kobject error handling

[Jun'ichi Nomura]

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Hi,

Excuse me for the long Cc list.
I kept people in the thread below in Cc.
http://marc.theaimsgroup.com/?l=linux-kernel&m=116221664710826&w=2

The patch below fixes bd_claim_by_kobject to release bdev correctly
in case that bd_claim succeeds but following add_bd_holder fails.

If it happens, the caller takes it didn't bd_claim() where actually
it did. The bdev becomes no longer bd_claim-able from others.
I don't have any reproducible test case for it but it's a bug.
The bug is introduced in 2.6.18-rc1-mm2 and now in 2.6.19-rc3.

Please consider to apply.

Thanks,
-- 
Jun'ichi Nomura, NEC Corporation of America

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The patch below fixes bd_claim_by_kobject to release bdev correctly
in case that bd_claim succeeds but following add_bd_holder fails.

 fs/block_dev.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>

--- linux-2.6.orig/fs/block_dev.c	2006-10-30 10:07:16.000000000 -0500
+++ linux-2.6/fs/block_dev.c	2006-10-30 15:38:21.000000000 -0500
@@ -751,8 +751,11 @@ static int bd_claim_by_kobject(struct bl
 
 	mutex_lock_nested(&bdev->bd_mutex, BD_MUTEX_PARTITION);
 	res = bd_claim(bdev, holder);
-	if (res == 0)
+	if (res == 0) {
 		res = add_bd_holder(bdev, bo);
+		if (res)
+			bd_release(bdev);
+	}
 	if (res)
 		free_bd_holder(bo);
 	mutex_unlock(&bdev->bd_mutex);