linux-kernel - [PATCH 2/1] block: make blk_init_free_list and elevator

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Date:	Tue, 25 May 2010 13:15:15 -0400
From:	Mike Snitzer <snitzer@...hat.com>
To:	Jens Axboe <jens.axboe@...cle.com>
Cc:	dm-devel@...hat.com, Alasdair Kergon <agk@...hat.com>,
	Kiyoshi Ueda <k-ueda@...jp.nec.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/1] block: make blk_init_free_list and elevator_init
 idempotent

blk_init_allocated_queue_node may fail and the caller _could_ retry.
Accommodate the unlikely event that blk_init_allocated_queue_node is
called on an already initialized (possibly partially) request_queue.

Signed-off-by: Mike Snitzer <snitzer@...hat.com>
---
 block/blk-core.c |    3 +++
 block/elevator.c |    6 ++++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index c0179b7..2c208c3 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -467,6 +467,9 @@ static int blk_init_free_list(struct request_queue *q)
 {
 	struct request_list *rl = &q->rq;
 
+	if (unlikely(rl->rq_pool))
+		return 0;
+
 	rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
 	rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
 	rl->elvpriv = 0;
diff --git a/block/elevator.c b/block/elevator.c
index 0abce47..923a913 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -242,9 +242,11 @@ int elevator_init(struct request_queue *q, char *name)
 {
 	struct elevator_type *e = NULL;
 	struct elevator_queue *eq;
-	int ret = 0;
 	void *data;
 
+	if (unlikely(q->elevator))
+		return 0;
+
 	INIT_LIST_HEAD(&q->queue_head);
 	q->last_merge = NULL;
 	q->end_sector = 0;
@@ -284,7 +286,7 @@ int elevator_init(struct request_queue *q, char *name)
 	}
 
 	elevator_attach(q, eq, data);
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL(elevator_init);
 
--
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