linux-ext4 - [PATCH 5/6] vfs: Add BUG_ON for delayed and unwritten flags in submit

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Message-Id: <1242168327-31127-6-git-send-email-tytso@mit.edu>
Date:	Tue, 12 May 2009 18:45:26 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	"Theodore Ts'o" <tytso@....edu>, linux-fsdevel@...r.kernel.org
Subject: [PATCH 5/6] vfs: Add BUG_ON for delayed and unwritten flags in submit_bh()

From: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>

The BH_Delay and BH_Unwritten flags should never leak out to
submit_bh().  So add some BUG_ON() checks to submit_bh so we can get a
stack trace and determine how and why this might have happened.

(Note that only XFS and ext4 use these buffer head flags, and XFS does
not use submit_bh().  So this patch should only modify behavior for
ext4.)

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
Cc: linux-fsdevel@...r.kernel.org
---
 fs/buffer.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index aed2977..ad01129 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2933,6 +2933,8 @@ int submit_bh(int rw, struct buffer_head * bh)
 	BUG_ON(!buffer_locked(bh));
 	BUG_ON(!buffer_mapped(bh));
 	BUG_ON(!bh->b_end_io);
+	BUG_ON(buffer_delay(bh));
+	BUG_ON(buffer_unwritten(bh));
 
 	/*
 	 * Mask in barrier bit for a write (could be either a WRITE or a
-- 
1.6.3.rc4.1.g3e14.dirty

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