diff options
| -rw-r--r-- | drivers/block/ll_rw_blk.c | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c index 67431f28015..5caebe2cf0a 100644 --- a/drivers/block/ll_rw_blk.c +++ b/drivers/block/ll_rw_blk.c @@ -1867,19 +1867,20 @@ static void freed_request(request_queue_t *q, int rw) #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist) /* - * Get a free request, queue_lock must not be held + * Get a free request, queue_lock must be held. + * Returns NULL on failure, with queue_lock held. + * Returns !NULL on success, with queue_lock *not held*. */ static struct request *get_request(request_queue_t *q, int rw, struct bio *bio, int gfp_mask) { struct request *rq = NULL; struct request_list *rl = &q->rq; - struct io_context *ioc = get_io_context(gfp_mask); + struct io_context *ioc = get_io_context(GFP_ATOMIC); if (unlikely(test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags))) goto out; - spin_lock_irq(q->queue_lock); if (rl->count[rw]+1 >= q->nr_requests) { /* * The queue will fill after this allocation, so set it as @@ -1907,7 +1908,6 @@ static struct request *get_request(request_queue_t *q, int rw, struct bio *bio, * The queue is full and the allocating process is not a * "batcher", and not exempted by the IO scheduler */ - spin_unlock_irq(q->queue_lock); goto out; } @@ -1950,7 +1950,6 @@ rq_starved: if (unlikely(rl->count[rw] == 0)) rl->starved[rw] = 1; - spin_unlock_irq(q->queue_lock); goto out; } @@ -1967,6 +1966,8 @@ out: /* * No available requests for this queue, unplug the device and wait for some * requests to become available. + * + * Called with q->queue_lock held, and returns with it unlocked. */ static struct request *get_request_wait(request_queue_t *q, int rw, struct bio *bio) @@ -1986,7 +1987,8 @@ static struct request *get_request_wait(request_queue_t *q, int rw, if (!rq) { struct io_context *ioc; - generic_unplug_device(q); + __generic_unplug_device(q); + spin_unlock_irq(q->queue_lock); io_schedule(); /* @@ -1998,6 +2000,8 @@ static struct request *get_request_wait(request_queue_t *q, int rw, ioc = get_io_context(GFP_NOIO); ioc_set_batching(q, ioc); put_io_context(ioc); + + spin_lock_irq(q->queue_lock); } finish_wait(&rl->wait[rw], &wait); } @@ -2011,14 +2015,18 @@ struct request *blk_get_request(request_queue_t *q, int rw, int gfp_mask) BUG_ON(rw != READ && rw != WRITE); - if (gfp_mask & __GFP_WAIT) + spin_lock_irq(q->queue_lock); + if (gfp_mask & __GFP_WAIT) { rq = get_request_wait(q, rw, NULL); - else + } else { rq = get_request(q, rw, NULL, gfp_mask); + if (!rq) + spin_unlock_irq(q->queue_lock); + } + /* q->queue_lock is unlocked at this point */ return rq; } - EXPORT_SYMBOL(blk_get_request); /** @@ -2605,9 +2613,10 @@ static int __make_request(request_queue_t *q, struct bio *bio) get_rq: /* * Grab a free request. This is might sleep but can not fail. + * Returns with the queue unlocked. */ - spin_unlock_irq(q->queue_lock); req = get_request_wait(q, rw, bio); + /* * After dropping the lock and possibly sleeping here, our request * may now be mergeable after it had proven unmergeable (above). |