From 86db1e29772372155db08ff48a9ceb76e11a2ad1 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 29 Jan 2008 14:53:40 +0100 Subject: block: continue ll_rw_blk.c splitup Adds files for barrier handling, rq execution, io context handling, mapping data to requests, and queue settings. Signed-off-by: Jens Axboe --- block/blk-barrier.c | 319 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 319 insertions(+) create mode 100644 block/blk-barrier.c (limited to 'block/blk-barrier.c') diff --git a/block/blk-barrier.c b/block/blk-barrier.c new file mode 100644 index 00000000000..5f74fec327d --- /dev/null +++ b/block/blk-barrier.c @@ -0,0 +1,319 @@ +/* + * Functions related to barrier IO handling + */ +#include +#include +#include +#include + +#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 "blk_queue_ordered: prepare_flush_fn required\n"); + 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 + */ +inline 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; + } + + rq->cmd_flags = REQ_HARDBARRIER; + rq_init(q, rq); + rq->elevator_private = NULL; + rq->elevator_private2 = NULL; + 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; + rq->cmd_flags = 0; + 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; + rq->elevator_private = NULL; + rq->elevator_private2 = NULL; + 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) + 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_UPTODATE)) + ret = -EIO; + + bio_put(bio); + return ret; +} + +EXPORT_SYMBOL(blkdev_issue_flush); -- cgit v1.2.3