Add 'discard' request handling
Some block devices benefit from a hint that they can forget the contents of certain sectors. Add basic support for this to the block core, along with a 'blkdev_issue_discard()' helper function which issues such requests. The caller doesn't get to provide an end_io functio, since blkdev_issue_discard() will automatically split the request up into multiple bios if appropriate. Neither does the function wait for completion -- it's expected that callers won't care about when, or even _if_, the request completes. It's only a hint to the device anyway. By definition, the file system doesn't _care_ about these sectors any more. [With feedback from OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> and Jens Axboe <jens.axboe@oracle.com] Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>hifive-unleashed-5.1
David Woodhouse
Jens Axboe
parent
d628eaef31
commit
fb2dce862d
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@ -315,3 +315,72 @@ int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
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return ret;
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}
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EXPORT_SYMBOL(blkdev_issue_flush);
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static void blkdev_discard_end_io(struct bio *bio, int err)
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{
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if (err) {
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if (err == -EOPNOTSUPP)
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set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
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clear_bit(BIO_UPTODATE, &bio->bi_flags);
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}
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bio_put(bio);
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}
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/**
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* blkdev_issue_discard - queue a discard
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* @bdev: blockdev to issue discard for
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* @sector: start sector
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* @nr_sects: number of sectors to discard
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*
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* Description:
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* Issue a discard request for the sectors in question. Does not wait.
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*/
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int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
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unsigned nr_sects)
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{
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struct request_queue *q;
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struct bio *bio;
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int ret = 0;
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if (bdev->bd_disk == NULL)
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return -ENXIO;
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q = bdev_get_queue(bdev);
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if (!q)
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return -ENXIO;
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if (!q->prepare_discard_fn)
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return -EOPNOTSUPP;
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while (nr_sects && !ret) {
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bio = bio_alloc(GFP_KERNEL, 0);
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if (!bio)
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return -ENOMEM;
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bio->bi_end_io = blkdev_discard_end_io;
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bio->bi_bdev = bdev;
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bio->bi_sector = sector;
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if (nr_sects > q->max_hw_sectors) {
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bio->bi_size = q->max_hw_sectors << 9;
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nr_sects -= q->max_hw_sectors;
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sector += q->max_hw_sectors;
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} else {
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bio->bi_size = nr_sects << 9;
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nr_sects = 0;
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}
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bio_get(bio);
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submit_bio(WRITE_DISCARD, bio);
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/* Check if it failed immediately */
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if (bio_flagged(bio, BIO_EOPNOTSUPP))
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ret = -EOPNOTSUPP;
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else if (!bio_flagged(bio, BIO_UPTODATE))
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ret = -EIO;
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bio_put(bio);
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}
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return ret;
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}
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EXPORT_SYMBOL(blkdev_issue_discard);
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@ -1079,6 +1079,10 @@ void init_request_from_bio(struct request *req, struct bio *bio)
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*/
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if (unlikely(bio_barrier(bio)))
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req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
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if (unlikely(bio_discard(bio))) {
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req->cmd_flags |= (REQ_SOFTBARRIER | REQ_DISCARD);
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req->q->prepare_discard_fn(req->q, req);
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}
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if (bio_sync(bio))
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req->cmd_flags |= REQ_RW_SYNC;
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@ -1095,7 +1099,7 @@ void init_request_from_bio(struct request *req, struct bio *bio)
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static int __make_request(struct request_queue *q, struct bio *bio)
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{
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struct request *req;
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int el_ret, nr_sectors, barrier, err;
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int el_ret, nr_sectors, barrier, discard, err;
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const unsigned short prio = bio_prio(bio);
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const int sync = bio_sync(bio);
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int rw_flags;
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@ -1115,6 +1119,12 @@ static int __make_request(struct request_queue *q, struct bio *bio)
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goto end_io;
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}
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discard = bio_discard(bio);
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if (unlikely(discard) && !q->prepare_discard_fn) {
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err = -EOPNOTSUPP;
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goto end_io;
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}
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spin_lock_irq(q->queue_lock);
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if (unlikely(barrier) || elv_queue_empty(q))
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@ -1405,7 +1415,8 @@ end_io:
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if (bio_check_eod(bio, nr_sectors))
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goto end_io;
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if (bio_empty_barrier(bio) && !q->prepare_flush_fn) {
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if ((bio_empty_barrier(bio) && !q->prepare_flush_fn) ||
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(bio_discard(bio) && !q->prepare_discard_fn)) {
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err = -EOPNOTSUPP;
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goto end_io;
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}
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@ -1487,7 +1498,6 @@ void submit_bio(int rw, struct bio *bio)
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* go through the normal accounting stuff before submission.
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*/
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if (bio_has_data(bio)) {
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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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@ -1881,7 +1891,7 @@ static int blk_end_io(struct request *rq, int error, unsigned int nr_bytes,
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struct request_queue *q = rq->q;
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unsigned long flags = 0UL;
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if (bio_has_data(rq->bio)) {
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if (bio_has_data(rq->bio) || blk_discard_rq(rq)) {
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if (__end_that_request_first(rq, error, nr_bytes))
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return 1;
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@ -1939,7 +1949,7 @@ EXPORT_SYMBOL_GPL(blk_end_request);
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**/
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int __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
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{
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if (bio_has_data(rq->bio) &&
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if ((bio_has_data(rq->bio) || blk_discard_rq(rq)) &&
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__end_that_request_first(rq, error, nr_bytes))
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return 1;
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@ -2012,12 +2022,14 @@ void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
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we want BIO_RW_AHEAD (bit 1) to imply REQ_FAILFAST (bit 1). */
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rq->cmd_flags |= (bio->bi_rw & 3);
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rq->nr_phys_segments = bio_phys_segments(q, bio);
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rq->nr_hw_segments = bio_hw_segments(q, bio);
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if (bio_has_data(bio)) {
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rq->nr_phys_segments = bio_phys_segments(q, bio);
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rq->nr_hw_segments = bio_hw_segments(q, bio);
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rq->buffer = bio_data(bio);
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}
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rq->current_nr_sectors = bio_cur_sectors(bio);
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rq->hard_cur_sectors = rq->current_nr_sectors;
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rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
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rq->buffer = bio_data(bio);
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rq->data_len = bio->bi_size;
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rq->bio = rq->biotail = bio;
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@ -32,6 +32,23 @@ void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
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}
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EXPORT_SYMBOL(blk_queue_prep_rq);
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/**
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* blk_queue_set_discard - set a discard_sectors function for queue
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* @q: queue
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* @dfn: prepare_discard function
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*
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* It's possible for a queue to register a discard callback which is used
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* to transform a discard request into the appropriate type for the
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* hardware. If none is registered, then discard requests are failed
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* with %EOPNOTSUPP.
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*
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*/
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void blk_queue_set_discard(struct request_queue *q, prepare_discard_fn *dfn)
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{
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q->prepare_discard_fn = dfn;
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}
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EXPORT_SYMBOL(blk_queue_set_discard);
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/**
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* blk_queue_merge_bvec - set a merge_bvec function for queue
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* @q: queue
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@ -149,6 +149,8 @@ struct bio {
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* bit 2 -- barrier
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* bit 3 -- fail fast, don't want low level driver retries
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* bit 4 -- synchronous I/O hint: the block layer will unplug immediately
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* bit 5 -- metadata request
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* bit 6 -- discard sectors
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*/
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#define BIO_RW 0 /* Must match RW in req flags (blkdev.h) */
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#define BIO_RW_AHEAD 1 /* Must match FAILFAST in req flags */
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@ -156,6 +158,7 @@ struct bio {
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#define BIO_RW_FAILFAST 3
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#define BIO_RW_SYNC 4
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#define BIO_RW_META 5
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#define BIO_RW_DISCARD 6
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/*
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* upper 16 bits of bi_rw define the io priority of this bio
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@ -186,13 +189,14 @@ struct bio {
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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_has_data(bio))
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#define bio_discard(bio) ((bio)->bi_rw & (1 << BIO_RW_DISCARD))
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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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else /* dataless requests such as discard */
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return bio->bi_size >> 9;
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}
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static inline void *bio_data(struct bio *bio)
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@ -89,6 +89,7 @@ enum {
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enum rq_flag_bits {
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__REQ_RW, /* not set, read. set, write */
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__REQ_FAILFAST, /* no low level driver retries */
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__REQ_DISCARD, /* request to discard sectors */
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__REQ_SORTED, /* elevator knows about this request */
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__REQ_SOFTBARRIER, /* may not be passed by ioscheduler */
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__REQ_HARDBARRIER, /* may not be passed by drive either */
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@ -111,6 +112,7 @@ enum rq_flag_bits {
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};
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#define REQ_RW (1 << __REQ_RW)
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#define REQ_DISCARD (1 << __REQ_DISCARD)
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#define REQ_FAILFAST (1 << __REQ_FAILFAST)
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#define REQ_SORTED (1 << __REQ_SORTED)
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#define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
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@ -252,6 +254,7 @@ typedef void (request_fn_proc) (struct request_queue *q);
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typedef int (make_request_fn) (struct request_queue *q, struct bio *bio);
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typedef int (prep_rq_fn) (struct request_queue *, struct request *);
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typedef void (unplug_fn) (struct request_queue *);
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typedef int (prepare_discard_fn) (struct request_queue *, struct request *);
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struct bio_vec;
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struct bvec_merge_data {
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@ -307,6 +310,7 @@ struct request_queue
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make_request_fn *make_request_fn;
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prep_rq_fn *prep_rq_fn;
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unplug_fn *unplug_fn;
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prepare_discard_fn *prepare_discard_fn;
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merge_bvec_fn *merge_bvec_fn;
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prepare_flush_fn *prepare_flush_fn;
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softirq_done_fn *softirq_done_fn;
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@ -546,6 +550,7 @@ enum {
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#define blk_sorted_rq(rq) ((rq)->cmd_flags & REQ_SORTED)
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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_discard_rq(rq) ((rq)->cmd_flags & REQ_DISCARD)
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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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/* rq->queuelist of dequeued request must be list_empty() */
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@ -796,6 +801,7 @@ extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);
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extern void blk_queue_dma_alignment(struct request_queue *, int);
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extern void blk_queue_update_dma_alignment(struct request_queue *, int);
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extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *);
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extern void blk_queue_set_discard(struct request_queue *, prepare_discard_fn *);
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extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
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extern int blk_queue_ordered(struct request_queue *, unsigned, prepare_flush_fn *);
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extern int blk_do_ordered(struct request_queue *, struct request **);
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@ -837,6 +843,16 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
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}
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extern int blkdev_issue_flush(struct block_device *, sector_t *);
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extern int blkdev_issue_discard(struct block_device *, sector_t sector,
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unsigned nr_sects);
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static inline int sb_issue_discard(struct super_block *sb,
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sector_t block, unsigned nr_blocks)
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{
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block <<= (sb->s_blocksize_bits - 9);
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nr_blocks <<= (sb->s_blocksize_bits - 9);
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return blkdev_issue_discard(sb->s_bdev, block, nr_blocks);
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}
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/*
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* command filter functions
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@ -86,7 +86,8 @@ extern int dir_notify_enable;
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#define READ_META (READ | (1 << BIO_RW_META))
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#define WRITE_SYNC (WRITE | (1 << BIO_RW_SYNC))
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#define SWRITE_SYNC (SWRITE | (1 << BIO_RW_SYNC))
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#define WRITE_BARRIER ((1 << BIO_RW) | (1 << BIO_RW_BARRIER))
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#define WRITE_BARRIER (WRITE | (1 << BIO_RW_BARRIER))
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#define WRITE_DISCARD (WRITE | (1 << BIO_RW_DISCARD))
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#define SEL_IN 1
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#define SEL_OUT 2
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