linux-ext4 - [PATCH 04/11] ocfs2: Fix possible deadlock in ocfs2_write

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Date:	Fri, 16 Jan 2009 19:08:12 +0100
From:	Jan Kara <jack@...e.cz>
To:	linux-kernel@...r.kernel.org
Cc:	linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Jan Kara <jack@...e.cz>
Subject: [PATCH 04/11] ocfs2: Fix possible deadlock in ocfs2_write_dquot()

It could happen that some limit has been set via quotactl() and in parallel
->mark_dirty() is called from another thread doing e.g. dquot_alloc_space(). In
such case ocfs2_write_dquot() must not try to sync the dquot because that needs
global quota lock but that ranks above transaction start.

Signed-off-by: Jan Kara <jack@...e.cz>
Acked-by: Mark Fasheh <mfasheh@...e.de>
---
 fs/ocfs2/quota_global.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index f4efa89..1ed0f7c 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -754,7 +754,9 @@ static int ocfs2_mark_dquot_dirty(struct dquot *dquot)
 	if (dquot->dq_flags & mask)
 		sync = 1;
 	spin_unlock(&dq_data_lock);
-	if (!sync) {
+	/* This is a slight hack but we can't afford getting global quota
+	 * lock if we already have a transaction started. */
+	if (!sync || journal_current_handle()) {
 		status = ocfs2_write_dquot(dquot);
 		goto out;
 	}
-- 
1.6.0.2

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