+++ /dev/null
-/*
- * Functions related to barrier IO handling
- */
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/bio.h>
-#include <linux/blkdev.h>
-#include <linux/gfp.h>
-
-#include "blk.h"
-
-/**
- * blk_queue_ordered - does this queue support ordered writes
- * @q: the request queue
- * @ordered: one of QUEUE_ORDERED_*
- *
- * 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)
-{
- 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;
-
- 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 (rq->cmd_type != REQ_TYPE_FS)
- 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_type = REQ_TYPE_FS;
- rq->cmd_flags = REQ_HARDBARRIER | REQ_FLUSH;
- rq->rq_disk = q->orig_bar_rq->rq_disk;
- rq->end_io = end_io;
-
- 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_WRITE;
- 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 = rq->cmd_type == REQ_TYPE_FS &&
- (rq->cmd_flags & REQ_HARDBARRIER);
-
- 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 (rq->cmd_type != REQ_TYPE_FS &&
- 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);
- }
- 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);
projects / mv-sheeva.git / blobdiff