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 <tj@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 248 insertions, 0 deletions

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 <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/gfp.h>
+
+#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);