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block: Initial support for data-less (or empty) barrier support
This implements functionality to pass down or insert a barrier in a queue, without having data attached to it. The ->prepare_flush_fn() infrastructure from data barriers are reused to provide this functionality. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
parent
c07e2b4129
commit
bf2de6f5a4
5 changed files with 71 additions and 21 deletions
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@ -712,6 +712,14 @@ struct request *elv_next_request(struct request_queue *q)
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int ret;
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while ((rq = __elv_next_request(q)) != NULL) {
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/*
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* Kill the empty barrier place holder, the driver must
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* not ever see it.
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*/
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if (blk_empty_barrier(rq)) {
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end_queued_request(rq, 1);
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continue;
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}
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if (!(rq->cmd_flags & REQ_STARTED)) {
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/*
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* This is the first time the device driver
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@ -458,9 +458,12 @@ static inline struct request *start_ordered(struct request_queue *q,
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* Queue ordered sequence. As we stack them at the head, we
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* need to queue in reverse order. Note that we rely on that
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* no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
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* request gets inbetween ordered sequence.
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* request gets inbetween ordered sequence. If this request is
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* an empty barrier, we don't need to do a postflush ever since
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* there will be no data written between the pre and post flush.
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* Hence a single flush will suffice.
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*/
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if (q->ordered & QUEUE_ORDERED_POSTFLUSH)
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if ((q->ordered & QUEUE_ORDERED_POSTFLUSH) && !blk_empty_barrier(rq))
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queue_flush(q, QUEUE_ORDERED_POSTFLUSH);
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else
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q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;
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@ -484,7 +487,7 @@ static inline struct request *start_ordered(struct request_queue *q,
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int blk_do_ordered(struct request_queue *q, struct request **rqp)
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{
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struct request *rq = *rqp;
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int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
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const int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
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if (!q->ordseq) {
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if (!is_barrier)
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@ -3054,7 +3057,7 @@ static inline void blk_partition_remap(struct bio *bio)
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{
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struct block_device *bdev = bio->bi_bdev;
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if (bdev != bdev->bd_contains) {
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if (bio_sectors(bio) && bdev != bdev->bd_contains) {
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struct hd_struct *p = bdev->bd_part;
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const int rw = bio_data_dir(bio);
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@ -3313,23 +3316,32 @@ void submit_bio(int rw, struct bio *bio)
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{
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int count = bio_sectors(bio);
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BIO_BUG_ON(!bio->bi_size);
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BIO_BUG_ON(!bio->bi_io_vec);
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bio->bi_rw |= rw;
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if (rw & WRITE) {
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count_vm_events(PGPGOUT, count);
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} else {
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task_io_account_read(bio->bi_size);
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count_vm_events(PGPGIN, count);
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}
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if (unlikely(block_dump)) {
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char b[BDEVNAME_SIZE];
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printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
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current->comm, current->pid,
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(rw & WRITE) ? "WRITE" : "READ",
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(unsigned long long)bio->bi_sector,
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bdevname(bio->bi_bdev,b));
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/*
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* If it's a regular read/write or a barrier with data attached,
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* go through the normal accounting stuff before submission.
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*/
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if (!bio_empty_barrier(bio)) {
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BIO_BUG_ON(!bio->bi_size);
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BIO_BUG_ON(!bio->bi_io_vec);
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if (rw & WRITE) {
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count_vm_events(PGPGOUT, count);
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} else {
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task_io_account_read(bio->bi_size);
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count_vm_events(PGPGIN, count);
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}
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if (unlikely(block_dump)) {
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char b[BDEVNAME_SIZE];
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printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
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current->comm, current->pid,
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(rw & WRITE) ? "WRITE" : "READ",
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(unsigned long long)bio->bi_sector,
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bdevname(bio->bi_bdev,b));
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}
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}
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generic_make_request(bio);
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@ -3405,6 +3417,14 @@ static int __end_that_request_first(struct request *req, int uptodate,
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while ((bio = req->bio) != NULL) {
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int nbytes;
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/*
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* For an empty barrier request, the low level driver must
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* store a potential error location in ->sector. We pass
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* that back up in ->bi_sector.
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*/
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if (blk_empty_barrier(req))
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bio->bi_sector = req->sector;
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if (nr_bytes >= bio->bi_size) {
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req->bio = bio->bi_next;
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nbytes = bio->bi_size;
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@ -176,13 +176,28 @@ struct bio {
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#define bio_offset(bio) bio_iovec((bio))->bv_offset
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#define bio_segments(bio) ((bio)->bi_vcnt - (bio)->bi_idx)
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#define bio_sectors(bio) ((bio)->bi_size >> 9)
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#define bio_cur_sectors(bio) (bio_iovec(bio)->bv_len >> 9)
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#define bio_data(bio) (page_address(bio_page((bio))) + bio_offset((bio)))
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#define bio_barrier(bio) ((bio)->bi_rw & (1 << BIO_RW_BARRIER))
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#define bio_sync(bio) ((bio)->bi_rw & (1 << BIO_RW_SYNC))
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#define bio_failfast(bio) ((bio)->bi_rw & (1 << BIO_RW_FAILFAST))
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#define bio_rw_ahead(bio) ((bio)->bi_rw & (1 << BIO_RW_AHEAD))
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#define bio_rw_meta(bio) ((bio)->bi_rw & (1 << BIO_RW_META))
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#define bio_empty_barrier(bio) (bio_barrier(bio) && !(bio)->bi_size)
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static inline unsigned int bio_cur_sectors(struct bio *bio)
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{
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if (bio->bi_vcnt)
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return bio_iovec(bio)->bv_len >> 9;
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return 0;
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}
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static inline void *bio_data(struct bio *bio)
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{
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if (bio->bi_vcnt)
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return page_address(bio_page(bio)) + bio_offset(bio);
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return NULL;
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}
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/*
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* will die
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@ -540,6 +540,7 @@ enum {
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#define blk_barrier_rq(rq) ((rq)->cmd_flags & REQ_HARDBARRIER)
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#define blk_fua_rq(rq) ((rq)->cmd_flags & REQ_FUA)
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#define blk_bidi_rq(rq) ((rq)->next_rq != NULL)
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#define blk_empty_barrier(rq) (blk_barrier_rq(rq) && blk_fs_request(rq) && !(rq)->hard_nr_sectors)
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#define list_entry_rq(ptr) list_entry((ptr), struct request, queuelist)
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@ -264,6 +264,12 @@ void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
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{
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mempool_t *pool;
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/*
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* Data-less bio, nothing to bounce
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*/
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if (bio_empty_barrier(*bio_orig))
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return;
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/*
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* for non-isa bounce case, just check if the bounce pfn is equal
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* to or bigger than the highest pfn in the system -- in that case,
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