diff options
Diffstat (limited to 'block/blk-barrier.c')
| -rw-r--r-- | block/blk-barrier.c | 317 |
1 files changed, 0 insertions, 317 deletions
diff --git a/block/blk-barrier.c b/block/blk-barrier.c deleted file mode 100644 index a09ead19f9c..00000000000 --- a/block/blk-barrier.c +++ /dev/null @@ -1,317 +0,0 @@ -/* - * 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 (ordered & (QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH) && - prepare_flush_fn == NULL) { - 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; -} - -void 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; - - /* - * Okay, sequence complete. - */ - q->ordseq = 0; - rq = q->orig_bar_rq; - - if (__blk_end_request(rq, q->orderr, blk_rq_bytes(rq))) - BUG(); -} - -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_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 struct request *start_ordered(struct request_queue *q, - struct request *rq) -{ - q->orderr = 0; - q->ordered = q->next_ordered; - q->ordseq |= QUEUE_ORDSEQ_STARTED; - - /* - * Prep proxy barrier request. - */ - blkdev_dequeue_request(rq); - q->orig_bar_rq = rq; - rq = &q->bar_rq; - 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_FUA) - rq->cmd_flags |= REQ_FUA; - init_request_from_bio(rq, q->orig_bar_rq->bio); - rq->end_io = bar_end_io; - - /* - * 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 this request is - * an empty barrier, we don't need to do a postflush ever since - * there will be no data written between the pre and post flush. - * Hence a single flush will suffice. - */ - if ((q->ordered & QUEUE_ORDERED_POSTFLUSH) && !blk_empty_barrier(rq)) - queue_flush(q, QUEUE_ORDERED_POSTFLUSH); - else - q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH; - - elv_insert(q, rq, ELEVATOR_INSERT_FRONT); - - if (q->ordered & QUEUE_ORDERED_PREFLUSH) { - queue_flush(q, QUEUE_ORDERED_PREFLUSH); - rq = &q->pre_flush_rq; - } else - q->ordseq |= QUEUE_ORDSEQ_PREFLUSH; - - if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0) - q->ordseq |= QUEUE_ORDSEQ_DRAIN; - else - rq = NULL; - - return rq; -} - -int 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 1; - - if (q->next_ordered != QUEUE_ORDERED_NONE) { - *rqp = start_ordered(q, rq); - return 1; - } else { - /* - * This can happen when the queue switches to - * ORDERED_NONE while this request is on it. - */ - blkdev_dequeue_request(rq); - if (__blk_end_request(rq, -EOPNOTSUPP, - blk_rq_bytes(rq))) - BUG(); - *rqp = NULL; - return 0; - } - } - - /* - * 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 1; - - if (q->ordered & QUEUE_ORDERED_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 1; -} - -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. Caller must run wait_for_completion() on its own. - */ -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); - if (!bio) - return -ENOMEM; - - bio->bi_end_io = bio_end_empty_barrier; - bio->bi_private = &wait; - bio->bi_bdev = bdev; - submit_bio(1 << BIO_RW_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 rq->sector. - */ - 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); |