From 8839a0e055d9abd6c011d533373a8dd266cad011 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 3 Sep 2010 11:56:16 +0200 Subject: block: rename blk-barrier.c to blk-flush.c Without ordering requirements, barrier and ordering are minomers. Rename block/blk-barrier.c to block/blk-flush.c. Rename of symbols will follow. Signed-off-by: Tejun Heo Cc: Christoph Hellwig Signed-off-by: Jens Axboe --- block/blk-flush.c | 248 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 248 insertions(+) create mode 100644 block/blk-flush.c (limited to 'block/blk-flush.c') diff --git a/block/blk-flush.c b/block/blk-flush.c new file mode 100644 index 000000000000..e8b2e5c091b1 --- /dev/null +++ b/block/blk-flush.c @@ -0,0 +1,248 @@ +/* + * Functions related to barrier IO handling + */ +#include +#include +#include +#include +#include + +#include "blk.h" + +static struct request *queue_next_ordseq(struct request_queue *q); + +/* + * 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); +} + +static struct request *blk_ordered_complete_seq(struct request_queue *q, + unsigned seq, int error) +{ + struct request *next_rq = NULL; + + if (error && !q->orderr) + q->orderr = error; + + BUG_ON(q->ordseq & seq); + q->ordseq |= seq; + + if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE) { + /* not complete yet, queue the next ordered sequence */ + next_rq = queue_next_ordseq(q); + } else { + /* complete this barrier request */ + __blk_end_request_all(q->orig_bar_rq, q->orderr); + q->orig_bar_rq = NULL; + q->ordseq = 0; + + /* dispatch the next barrier if there's one */ + if (!list_empty(&q->pending_barriers)) { + next_rq = list_entry_rq(q->pending_barriers.next); + list_move(&next_rq->queuelist, &q->queue_head); + } + } + return next_rq; +} + +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, struct request *rq, + rq_end_io_fn *end_io) +{ + blk_rq_init(q, rq); + rq->cmd_type = REQ_TYPE_FS; + rq->cmd_flags = REQ_FLUSH; + rq->rq_disk = q->orig_bar_rq->rq_disk; + rq->end_io = end_io; + + elv_insert(q, rq, ELEVATOR_INSERT_FRONT); +} + +static struct request *queue_next_ordseq(struct request_queue *q) +{ + struct request *rq = &q->bar_rq; + + switch (blk_ordered_cur_seq(q)) { + case QUEUE_ORDSEQ_PREFLUSH: + queue_flush(q, rq, pre_flush_end_io); + break; + + case QUEUE_ORDSEQ_BAR: + /* initialize proxy request and queue it */ + blk_rq_init(q, rq); + init_request_from_bio(rq, q->orig_bar_rq->bio); + rq->cmd_flags &= ~REQ_HARDBARRIER; + if (q->ordered & QUEUE_ORDERED_DO_FUA) + rq->cmd_flags |= REQ_FUA; + rq->end_io = bar_end_io; + + elv_insert(q, rq, ELEVATOR_INSERT_FRONT); + break; + + case QUEUE_ORDSEQ_POSTFLUSH: + queue_flush(q, rq, post_flush_end_io); + break; + + default: + BUG(); + } + return rq; +} + +struct request *blk_do_ordered(struct request_queue *q, struct request *rq) +{ + unsigned skip = 0; + + if (!(rq->cmd_flags & REQ_HARDBARRIER)) + return rq; + + if (q->ordseq) { + /* + * Barrier is already in progress and they can't be + * processed in parallel. Queue for later processing. + */ + list_move_tail(&rq->queuelist, &q->pending_barriers); + return NULL; + } + + if (unlikely(q->next_ordered == QUEUE_ORDERED_NONE)) { + /* + * Queue ordering not supported. Terminate + * with prejudice. + */ + blk_dequeue_request(rq); + __blk_end_request_all(rq, -EOPNOTSUPP); + return NULL; + } + + /* + * Start a new ordered sequence + */ + 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); + + /* stash away the original request */ + blk_dequeue_request(rq); + q->orig_bar_rq = rq; + + if (!(q->ordered & QUEUE_ORDERED_DO_PREFLUSH)) + skip |= QUEUE_ORDSEQ_PREFLUSH; + + if (!(q->ordered & QUEUE_ORDERED_DO_BAR)) + skip |= QUEUE_ORDSEQ_BAR; + + if (!(q->ordered & QUEUE_ORDERED_DO_POSTFLUSH)) + skip |= QUEUE_ORDSEQ_POSTFLUSH; + + /* complete skipped sequences and return the first sequence */ + return blk_ordered_complete_seq(q, skip, 0); +} + +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); + } + if (bio->bi_private) + complete(bio->bi_private); + bio_put(bio); +} + +/** + * blkdev_issue_flush - queue a flush + * @bdev: blockdev to issue flush for + * @gfp_mask: memory allocation flags (for bio_alloc) + * @error_sector: error sector + * @flags: BLKDEV_IFL_* flags to control behaviour + * + * 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. If WAIT flag is not passed then caller may check only what + * request was pushed in some internal queue for later handling. + */ +int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask, + sector_t *error_sector, unsigned long flags) +{ + DECLARE_COMPLETION_ONSTACK(wait); + 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; + + /* + * some block devices may not have their queue correctly set up here + * (e.g. loop device without a backing file) and so issuing a flush + * here will panic. Ensure there is a request function before issuing + * the barrier. + */ + if (!q->make_request_fn) + return -ENXIO; + + bio = bio_alloc(gfp_mask, 0); + bio->bi_end_io = bio_end_empty_barrier; + bio->bi_bdev = bdev; + if (test_bit(BLKDEV_WAIT, &flags)) + bio->bi_private = &wait; + + bio_get(bio); + submit_bio(WRITE_BARRIER, bio); + if (test_bit(BLKDEV_WAIT, &flags)) { + 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; + } + + 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); -- cgit