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Commit a492f075 authored by Joe Lawrence's avatar Joe Lawrence Committed by Jens Axboe
Browse files

block,scsi: fixup blk_get_request dead queue scenarios 



The blk_get_request function may fail in low-memory conditions or during
device removal (even if __GFP_WAIT is set). To distinguish between these
errors, modify the blk_get_request call stack to return the appropriate
ERR_PTR. Verify that all callers check the return status and consider
IS_ERR instead of a simple NULL pointer check.

For consistency, make a similar change to the blk_mq_alloc_request leg
of blk_get_request.  It may fail if the queue is dead, or the caller was
unwilling to wait.

Signed-off-by: default avatarJoe Lawrence <joe.lawrence@stratus.com>
Acked-by: Jiri Kosina <jkosina@suse.cz> [for pktdvd]
Acked-by: Boaz Harrosh <bharrosh@panasas.com> [for osd]
Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent eb571eea

block/blk-core.c

+17 −17
Original line number Diff line number Diff line
@@ -933,9 +933,9 @@ static struct io_context *rq_ioc(struct bio *bio) 
 * Get a free request from @q.  This function may fail under memory

 * pressure or if @q is dead.

 *

 * Must be callled with @q->queue_lock held and,

 * Returns %NULL on failure, with @q->queue_lock held.

 * Returns !%NULL on success, with @q->queue_lock *not held*.

 * Must be called with @q->queue_lock held and,

 * Returns ERR_PTR on failure, with @q->queue_lock held.

 * Returns request pointer on success, with @q->queue_lock *not held*.

 */

static struct request *__get_request(struct request_list *rl, int rw_flags,

				     struct bio *bio, gfp_t gfp_mask)
@@ -949,7 +949,7 @@ static struct request *__get_request(struct request_list *rl, int rw_flags, 
	int may_queue;



	if (unlikely(blk_queue_dying(q)))

		return NULL;

		return ERR_PTR(-ENODEV);



	may_queue = elv_may_queue(q, rw_flags);

	if (may_queue == ELV_MQUEUE_NO)
@@ -974,7 +974,7 @@ static struct request *__get_request(struct request_list *rl, int rw_flags, 
					 * process is not a "batcher", and not

					 * exempted by the IO scheduler

					 */

					return NULL;

					return ERR_PTR(-ENOMEM);

				}

			}

		}
@@ -992,7 +992,7 @@ static struct request *__get_request(struct request_list *rl, int rw_flags, 
	 * allocated with any setting of ->nr_requests

	 */

	if (rl->count[is_sync] >= (3 * q->nr_requests / 2))

		return NULL;

		return ERR_PTR(-ENOMEM);



	q->nr_rqs[is_sync]++;

	rl->count[is_sync]++;
@@ -1097,7 +1097,7 @@ static struct request *__get_request(struct request_list *rl, int rw_flags, 
rq_starved:

	if (unlikely(rl->count[is_sync] == 0))

		rl->starved[is_sync] = 1;

	return NULL;

	return ERR_PTR(-ENOMEM);

}



/**
@@ -1110,9 +1110,9 @@ static struct request *__get_request(struct request_list *rl, int rw_flags, 
 * Get a free request from @q.  If %__GFP_WAIT is set in @gfp_mask, this

 * function keeps retrying under memory pressure and fails iff @q is dead.

 *

 * Must be callled with @q->queue_lock held and,

 * Returns %NULL on failure, with @q->queue_lock held.

 * Returns !%NULL on success, with @q->queue_lock *not held*.

 * Must be called with @q->queue_lock held and,

 * Returns ERR_PTR on failure, with @q->queue_lock held.

 * Returns request pointer on success, with @q->queue_lock *not held*.

 */

static struct request *get_request(struct request_queue *q, int rw_flags,

				   struct bio *bio, gfp_t gfp_mask)
@@ -1125,12 +1125,12 @@ static struct request *get_request(struct request_queue *q, int rw_flags, 
	rl = blk_get_rl(q, bio);	/* transferred to @rq on success */

retry:

	rq = __get_request(rl, rw_flags, bio, gfp_mask);

	if (rq)

	if (!IS_ERR(rq))

		return rq;



	if (!(gfp_mask & __GFP_WAIT) || unlikely(blk_queue_dying(q))) {

		blk_put_rl(rl);

		return NULL;

		return rq;

	}



	/* wait on @rl and retry */
@@ -1167,7 +1167,7 @@ static struct request *blk_old_get_request(struct request_queue *q, int rw, 


	spin_lock_irq(q->queue_lock);

	rq = get_request(q, rw, NULL, gfp_mask);

	if (!rq)

	if (IS_ERR(rq))

		spin_unlock_irq(q->queue_lock);

	/* q->queue_lock is unlocked at this point */
@@ -1219,8 +1219,8 @@ struct request *blk_make_request(struct request_queue *q, struct bio *bio, 
{

	struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);



	if (unlikely(!rq))

		return ERR_PTR(-ENOMEM);

	if (IS_ERR(rq))

		return rq;



	blk_rq_set_block_pc(rq);
@@ -1615,8 +1615,8 @@ void blk_queue_bio(struct request_queue *q, struct bio *bio) 
	 * Returns with the queue unlocked.

	 */

	req = get_request(q, rw_flags, bio, GFP_NOIO);

	if (unlikely(!req)) {

		bio_endio(bio, -ENODEV);	/* @q is dead */

	if (IS_ERR(req)) {

		bio_endio(bio, PTR_ERR(req));	/* @q is dead */

		goto out_unlock;

	}

block/blk-mq.c

+6 −2
Original line number Diff line number Diff line
@@ -218,9 +218,11 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp, 
	struct blk_mq_hw_ctx *hctx;

	struct request *rq;

	struct blk_mq_alloc_data alloc_data;

	int ret;



	if (blk_mq_queue_enter(q))

		return NULL;

	ret = blk_mq_queue_enter(q);

	if (ret)

		return ERR_PTR(ret);



	ctx = blk_mq_get_ctx(q);

	hctx = q->mq_ops->map_queue(q, ctx->cpu);
@@ -240,6 +242,8 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp, 
		ctx = alloc_data.ctx;

	}

	blk_mq_put_ctx(ctx);

	if (!rq)

		return ERR_PTR(-EWOULDBLOCK);

	return rq;

}

EXPORT_SYMBOL(blk_mq_alloc_request);

block/bsg.c

+4 −4
Original line number Diff line number Diff line
@@ -270,8 +270,8 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm, 
	 * map scatter-gather elements separately and string them to request

	 */

	rq = blk_get_request(q, rw, GFP_KERNEL);

	if (!rq)

		return ERR_PTR(-ENOMEM);

	if (IS_ERR(rq))

		return rq;

	blk_rq_set_block_pc(rq);



	ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
@@ -285,8 +285,8 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm, 
		}



		next_rq = blk_get_request(q, READ, GFP_KERNEL);

		if (!next_rq) {

			ret = -ENOMEM;

		if (IS_ERR(next_rq)) {

			ret = PTR_ERR(next_rq);

			goto out;

		}

		rq->next_rq = next_rq;

block/scsi_ioctl.c

+6 −6
Original line number Diff line number Diff line
@@ -318,8 +318,8 @@ static int sg_io(struct request_queue *q, struct gendisk *bd_disk, 
		at_head = 1;



	rq = blk_get_request(q, writing ? WRITE : READ, GFP_KERNEL);

	if (!rq)

		return -ENOMEM;

	if (IS_ERR(rq))

		return PTR_ERR(rq);

	blk_rq_set_block_pc(rq);



	if (blk_fill_sghdr_rq(q, rq, hdr, mode)) {
@@ -448,8 +448,8 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode, 
	}



	rq = blk_get_request(q, in_len ? WRITE : READ, __GFP_WAIT);

	if (!rq) {

		err = -ENODEV;

	if (IS_ERR(rq)) {

		err = PTR_ERR(rq);

		goto error_free_buffer;

	}
@@ -539,8 +539,8 @@ static int __blk_send_generic(struct request_queue *q, struct gendisk *bd_disk, 
	int err;



	rq = blk_get_request(q, WRITE, __GFP_WAIT);

	if (!rq)

		return -ENODEV;

	if (IS_ERR(rq))

		return PTR_ERR(rq);

	blk_rq_set_block_pc(rq);

	rq->timeout = BLK_DEFAULT_SG_TIMEOUT;

	rq->cmd[0] = cmd;

drivers/block/paride/pd.c

+2 −2
Original line number Diff line number Diff line
@@ -722,8 +722,8 @@ static int pd_special_command(struct pd_unit *disk, 
	int err = 0;



	rq = blk_get_request(disk->gd->queue, READ, __GFP_WAIT);

	if (!rq)

		return -ENODEV;

	if (IS_ERR(rq))

		return PTR_ERR(rq);



	rq->cmd_type = REQ_TYPE_SPECIAL;

	rq->special = func;