| /* |
| * Functions related to barrier IO handling |
| */ |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/bio.h> |
| #include <linux/blkdev.h> |
| |
| #include "blk.h" |
| |
| /** |
| * blk_queue_ordered - does this queue support ordered writes |
| * @q: the request queue |
| * @ordered: one of QUEUE_ORDERED_* |
| * @prepare_flush_fn: rq setup helper for cache flush ordered writes |
| * |
| * Description: |
| * For journalled file systems, doing ordered writes on a commit |
| * block instead of explicitly doing wait_on_buffer (which is bad |
| * for performance) can be a big win. Block drivers supporting this |
| * feature should call this function and indicate so. |
| * |
| **/ |
| int blk_queue_ordered(struct request_queue *q, unsigned ordered, |
| prepare_flush_fn *prepare_flush_fn) |
| { |
| if (!prepare_flush_fn && (ordered & (QUEUE_ORDERED_DO_PREFLUSH | |
| QUEUE_ORDERED_DO_POSTFLUSH))) { |
| printk(KERN_ERR "%s: prepare_flush_fn required\n", __func__); |
| return -EINVAL; |
| } |
| |
| if (ordered != QUEUE_ORDERED_NONE && |
| ordered != QUEUE_ORDERED_DRAIN && |
| ordered != QUEUE_ORDERED_DRAIN_FLUSH && |
| ordered != QUEUE_ORDERED_DRAIN_FUA && |
| ordered != QUEUE_ORDERED_TAG && |
| ordered != QUEUE_ORDERED_TAG_FLUSH && |
| ordered != QUEUE_ORDERED_TAG_FUA) { |
| printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered); |
| return -EINVAL; |
| } |
| |
| q->ordered = ordered; |
| q->next_ordered = ordered; |
| q->prepare_flush_fn = prepare_flush_fn; |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(blk_queue_ordered); |
| |
| /* |
| * Cache flushing for ordered writes handling |
| */ |
| unsigned blk_ordered_cur_seq(struct request_queue *q) |
| { |
| if (!q->ordseq) |
| return 0; |
| return 1 << ffz(q->ordseq); |
| } |
| |
| unsigned blk_ordered_req_seq(struct request *rq) |
| { |
| struct request_queue *q = rq->q; |
| |
| BUG_ON(q->ordseq == 0); |
| |
| if (rq == &q->pre_flush_rq) |
| return QUEUE_ORDSEQ_PREFLUSH; |
| if (rq == &q->bar_rq) |
| return QUEUE_ORDSEQ_BAR; |
| if (rq == &q->post_flush_rq) |
| return QUEUE_ORDSEQ_POSTFLUSH; |
| |
| /* |
| * !fs requests don't need to follow barrier ordering. Always |
| * put them at the front. This fixes the following deadlock. |
| * |
| * http://thread.gmane.org/gmane.linux.kernel/537473 |
| */ |
| if (!blk_fs_request(rq)) |
| return QUEUE_ORDSEQ_DRAIN; |
| |
| if ((rq->cmd_flags & REQ_ORDERED_COLOR) == |
| (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR)) |
| return QUEUE_ORDSEQ_DRAIN; |
| else |
| return QUEUE_ORDSEQ_DONE; |
| } |
| |
| bool blk_ordered_complete_seq(struct request_queue *q, unsigned seq, int error) |
| { |
| struct request *rq; |
| |
| if (error && !q->orderr) |
| q->orderr = error; |
| |
| BUG_ON(q->ordseq & seq); |
| q->ordseq |= seq; |
| |
| if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE) |
| return false; |
| |
| /* |
| * Okay, sequence complete. |
| */ |
| q->ordseq = 0; |
| rq = q->orig_bar_rq; |
| __blk_end_request_all(rq, q->orderr); |
| return true; |
| } |
| |
| static void pre_flush_end_io(struct request *rq, int error) |
| { |
| elv_completed_request(rq->q, rq); |
| blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error); |
| } |
| |
| static void bar_end_io(struct request *rq, int error) |
| { |
| elv_completed_request(rq->q, rq); |
| blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error); |
| } |
| |
| static void post_flush_end_io(struct request *rq, int error) |
| { |
| elv_completed_request(rq->q, rq); |
| blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error); |
| } |
| |
| static void queue_flush(struct request_queue *q, unsigned which) |
| { |
| struct request *rq; |
| rq_end_io_fn *end_io; |
| |
| if (which == QUEUE_ORDERED_DO_PREFLUSH) { |
| rq = &q->pre_flush_rq; |
| end_io = pre_flush_end_io; |
| } else { |
| rq = &q->post_flush_rq; |
| end_io = post_flush_end_io; |
| } |
| |
| blk_rq_init(q, rq); |
| rq->cmd_flags = REQ_HARDBARRIER; |
| rq->rq_disk = q->bar_rq.rq_disk; |
| rq->end_io = end_io; |
| q->prepare_flush_fn(q, rq); |
| |
| elv_insert(q, rq, ELEVATOR_INSERT_FRONT); |
| } |
| |
| static inline bool start_ordered(struct request_queue *q, struct request **rqp) |
| { |
| struct request *rq = *rqp; |
| unsigned skip = 0; |
| |
| q->orderr = 0; |
| q->ordered = q->next_ordered; |
| q->ordseq |= QUEUE_ORDSEQ_STARTED; |
| |
| /* |
| * For an empty barrier, there's no actual BAR request, which |
| * in turn makes POSTFLUSH unnecessary. Mask them off. |
| */ |
| if (!blk_rq_sectors(rq)) { |
| q->ordered &= ~(QUEUE_ORDERED_DO_BAR | |
| QUEUE_ORDERED_DO_POSTFLUSH); |
| /* |
| * Empty barrier on a write-through device w/ ordered |
| * tag has no command to issue and without any command |
| * to issue, ordering by tag can't be used. Drain |
| * instead. |
| */ |
| if ((q->ordered & QUEUE_ORDERED_BY_TAG) && |
| !(q->ordered & QUEUE_ORDERED_DO_PREFLUSH)) { |
| q->ordered &= ~QUEUE_ORDERED_BY_TAG; |
| q->ordered |= QUEUE_ORDERED_BY_DRAIN; |
| } |
| } |
| |
| /* stash away the original request */ |
| blk_dequeue_request(rq); |
| q->orig_bar_rq = rq; |
| rq = NULL; |
| |
| /* |
| * Queue ordered sequence. As we stack them at the head, we |
| * need to queue in reverse order. Note that we rely on that |
| * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs |
| * request gets inbetween ordered sequence. |
| */ |
| if (q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) { |
| queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH); |
| rq = &q->post_flush_rq; |
| } else |
| skip |= QUEUE_ORDSEQ_POSTFLUSH; |
| |
| if (q->ordered & QUEUE_ORDERED_DO_BAR) { |
| rq = &q->bar_rq; |
| |
| /* initialize proxy request and queue it */ |
| blk_rq_init(q, rq); |
| if (bio_data_dir(q->orig_bar_rq->bio) == WRITE) |
| rq->cmd_flags |= REQ_RW; |
| if (q->ordered & QUEUE_ORDERED_DO_FUA) |
| rq->cmd_flags |= REQ_FUA; |
| init_request_from_bio(rq, q->orig_bar_rq->bio); |
| rq->end_io = bar_end_io; |
| |
| elv_insert(q, rq, ELEVATOR_INSERT_FRONT); |
| } else |
| skip |= QUEUE_ORDSEQ_BAR; |
| |
| if (q->ordered & QUEUE_ORDERED_DO_PREFLUSH) { |
| queue_flush(q, QUEUE_ORDERED_DO_PREFLUSH); |
| rq = &q->pre_flush_rq; |
| } else |
| skip |= QUEUE_ORDSEQ_PREFLUSH; |
| |
| if ((q->ordered & QUEUE_ORDERED_BY_DRAIN) && queue_in_flight(q)) |
| rq = NULL; |
| else |
| skip |= QUEUE_ORDSEQ_DRAIN; |
| |
| *rqp = rq; |
| |
| /* |
| * Complete skipped sequences. If whole sequence is complete, |
| * return false to tell elevator that this request is gone. |
| */ |
| return !blk_ordered_complete_seq(q, skip, 0); |
| } |
| |
| bool blk_do_ordered(struct request_queue *q, struct request **rqp) |
| { |
| struct request *rq = *rqp; |
| const int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq); |
| |
| if (!q->ordseq) { |
| if (!is_barrier) |
| return true; |
| |
| if (q->next_ordered != QUEUE_ORDERED_NONE) |
| return start_ordered(q, rqp); |
| else { |
| /* |
| * Queue ordering not supported. Terminate |
| * with prejudice. |
| */ |
| blk_dequeue_request(rq); |
| __blk_end_request_all(rq, -EOPNOTSUPP); |
| *rqp = NULL; |
| return false; |
| } |
| } |
| |
| /* |
| * Ordered sequence in progress |
| */ |
| |
| /* Special requests are not subject to ordering rules. */ |
| if (!blk_fs_request(rq) && |
| rq != &q->pre_flush_rq && rq != &q->post_flush_rq) |
| return true; |
| |
| if (q->ordered & QUEUE_ORDERED_BY_TAG) { |
| /* Ordered by tag. Blocking the next barrier is enough. */ |
| if (is_barrier && rq != &q->bar_rq) |
| *rqp = NULL; |
| } else { |
| /* Ordered by draining. Wait for turn. */ |
| WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q)); |
| if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q)) |
| *rqp = NULL; |
| } |
| |
| return true; |
| } |
| |
| static void bio_end_empty_barrier(struct bio *bio, int err) |
| { |
| if (err) { |
| if (err == -EOPNOTSUPP) |
| set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); |
| clear_bit(BIO_UPTODATE, &bio->bi_flags); |
| } |
| |
| complete(bio->bi_private); |
| } |
| |
| /** |
| * blkdev_issue_flush - queue a flush |
| * @bdev: blockdev to issue flush for |
| * @error_sector: error sector |
| * |
| * Description: |
| * Issue a flush for the block device in question. Caller can supply |
| * room for storing the error offset in case of a flush error, if they |
| * wish to. |
| */ |
| int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector) |
| { |
| DECLARE_COMPLETION_ONSTACK(wait); |
| struct request_queue *q; |
| struct bio *bio; |
| int ret; |
| |
| if (bdev->bd_disk == NULL) |
| return -ENXIO; |
| |
| q = bdev_get_queue(bdev); |
| if (!q) |
| return -ENXIO; |
| |
| bio = bio_alloc(GFP_KERNEL, 0); |
| bio->bi_end_io = bio_end_empty_barrier; |
| bio->bi_private = &wait; |
| bio->bi_bdev = bdev; |
| submit_bio(WRITE_BARRIER, bio); |
| |
| wait_for_completion(&wait); |
| |
| /* |
| * The driver must store the error location in ->bi_sector, if |
| * it supports it. For non-stacked drivers, this should be copied |
| * from blk_rq_pos(rq). |
| */ |
| if (error_sector) |
| *error_sector = bio->bi_sector; |
| |
| ret = 0; |
| if (bio_flagged(bio, BIO_EOPNOTSUPP)) |
| ret = -EOPNOTSUPP; |
| else if (!bio_flagged(bio, BIO_UPTODATE)) |
| ret = -EIO; |
| |
| bio_put(bio); |
| return ret; |
| } |
| EXPORT_SYMBOL(blkdev_issue_flush); |
| |
| static void blkdev_discard_end_io(struct bio *bio, int err) |
| { |
| if (err) { |
| if (err == -EOPNOTSUPP) |
| set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); |
| clear_bit(BIO_UPTODATE, &bio->bi_flags); |
| } |
| |
| bio_put(bio); |
| } |
| |
| /** |
| * blkdev_issue_discard - queue a discard |
| * @bdev: blockdev to issue discard for |
| * @sector: start sector |
| * @nr_sects: number of sectors to discard |
| * @gfp_mask: memory allocation flags (for bio_alloc) |
| * |
| * Description: |
| * Issue a discard request for the sectors in question. Does not wait. |
| */ |
| int blkdev_issue_discard(struct block_device *bdev, |
| sector_t sector, sector_t nr_sects, gfp_t gfp_mask) |
| { |
| struct request_queue *q; |
| struct bio *bio; |
| int ret = 0; |
| |
| if (bdev->bd_disk == NULL) |
| return -ENXIO; |
| |
| q = bdev_get_queue(bdev); |
| if (!q) |
| return -ENXIO; |
| |
| if (!q->prepare_discard_fn) |
| return -EOPNOTSUPP; |
| |
| while (nr_sects && !ret) { |
| bio = bio_alloc(gfp_mask, 0); |
| if (!bio) |
| return -ENOMEM; |
| |
| bio->bi_end_io = blkdev_discard_end_io; |
| bio->bi_bdev = bdev; |
| |
| bio->bi_sector = sector; |
| |
| if (nr_sects > q->max_hw_sectors) { |
| bio->bi_size = q->max_hw_sectors << 9; |
| nr_sects -= q->max_hw_sectors; |
| sector += q->max_hw_sectors; |
| } else { |
| bio->bi_size = nr_sects << 9; |
| nr_sects = 0; |
| } |
| bio_get(bio); |
| submit_bio(DISCARD_BARRIER, bio); |
| |
| /* Check if it failed immediately */ |
| if (bio_flagged(bio, BIO_EOPNOTSUPP)) |
| ret = -EOPNOTSUPP; |
| else if (!bio_flagged(bio, BIO_UPTODATE)) |
| ret = -EIO; |
| bio_put(bio); |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL(blkdev_issue_discard); |