Commit e67b77c7 authored by Jeff Moyer's avatar Jeff Moyer Committed by Jens Axboe
Browse files

blk-flush: move the queue kick into

A dm-multipath user reported[1] a problem when trying to boot
a kernel with commit 4853abaa
(block: fix flush machinery for stacking drivers with differring
flush flags) applied.  It turns out that an empty flush request
can be sent into blk_insert_flush.  When the BUG_ON was fixed
to allow for this, I/O on the underlying device would stall.  The
reason is that blk_insert_cloned_request does not kick the queue.
In the aforementioned commit, I had added a special case to
kick the queue if data was sent down but the queue flags did
not require a flush.  A better solution is to push the queue
kick up into blk_insert_cloned_request.

This patch, along with a follow-on which fixes the BUG_ON, fixes
the issue reported.

[1] http://www.redhat.com/archives/dm-devel/2011-September/msg00154.html

Reported-by: default avatarChristophe Saout <christophe@saout.de>
Signed-off-by: default avatarJeff Moyer <jmoyer@redhat.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>

Stable note: 3.1
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 834f9f61
...@@ -1725,6 +1725,8 @@ int blk_insert_cloned_request(struct request_queue *q, struct request *rq) ...@@ -1725,6 +1725,8 @@ int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
where = ELEVATOR_INSERT_FLUSH; where = ELEVATOR_INSERT_FLUSH;
add_acct_request(q, rq, where); add_acct_request(q, rq, where);
if (where == ELEVATOR_INSERT_FLUSH)
__blk_run_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags); spin_unlock_irqrestore(q->queue_lock, flags);
return 0; return 0;
......
...@@ -330,7 +330,6 @@ void blk_insert_flush(struct request *rq) ...@@ -330,7 +330,6 @@ void blk_insert_flush(struct request *rq)
if ((policy & REQ_FSEQ_DATA) && if ((policy & REQ_FSEQ_DATA) &&
!(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) { !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
list_add_tail(&rq->queuelist, &q->queue_head); list_add_tail(&rq->queuelist, &q->queue_head);
blk_run_queue_async(q);
return; return;
} }
......
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