From fb2dce862d9f9a68e6b9374579056ec9eca02a63 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Tue, 5 Aug 2008 18:01:53 +0100 Subject: 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 and Jens Axboe Signed-off-by: Jens Axboe --- include/linux/bio.h | 8 ++++++-- include/linux/blkdev.h | 16 ++++++++++++++++ include/linux/fs.h | 3 ++- 3 files changed, 24 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/bio.h b/include/linux/bio.h index 17f1fbdb31bf..1fdfc5621c83 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -149,6 +149,8 @@ struct bio { * bit 2 -- barrier * bit 3 -- fail fast, don't want low level driver retries * bit 4 -- synchronous I/O hint: the block layer will unplug immediately + * bit 5 -- metadata request + * bit 6 -- discard sectors */ #define BIO_RW 0 /* Must match RW in req flags (blkdev.h) */ #define BIO_RW_AHEAD 1 /* Must match FAILFAST in req flags */ @@ -156,6 +158,7 @@ struct bio { #define BIO_RW_FAILFAST 3 #define BIO_RW_SYNC 4 #define BIO_RW_META 5 +#define BIO_RW_DISCARD 6 /* * upper 16 bits of bi_rw define the io priority of this bio @@ -186,13 +189,14 @@ struct bio { #define bio_rw_ahead(bio) ((bio)->bi_rw & (1 << BIO_RW_AHEAD)) #define bio_rw_meta(bio) ((bio)->bi_rw & (1 << BIO_RW_META)) #define bio_empty_barrier(bio) (bio_barrier(bio) && !bio_has_data(bio)) +#define bio_discard(bio) ((bio)->bi_rw & (1 << BIO_RW_DISCARD)) static inline unsigned int bio_cur_sectors(struct bio *bio) { if (bio->bi_vcnt) return bio_iovec(bio)->bv_len >> 9; - - return 0; + else /* dataless requests such as discard */ + return bio->bi_size >> 9; } static inline void *bio_data(struct bio *bio) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index e0ba018f5e88..26ececbbebe2 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -89,6 +89,7 @@ enum { enum rq_flag_bits { __REQ_RW, /* not set, read. set, write */ __REQ_FAILFAST, /* no low level driver retries */ + __REQ_DISCARD, /* request to discard sectors */ __REQ_SORTED, /* elevator knows about this request */ __REQ_SOFTBARRIER, /* may not be passed by ioscheduler */ __REQ_HARDBARRIER, /* may not be passed by drive either */ @@ -111,6 +112,7 @@ enum rq_flag_bits { }; #define REQ_RW (1 << __REQ_RW) +#define REQ_DISCARD (1 << __REQ_DISCARD) #define REQ_FAILFAST (1 << __REQ_FAILFAST) #define REQ_SORTED (1 << __REQ_SORTED) #define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER) @@ -252,6 +254,7 @@ typedef void (request_fn_proc) (struct request_queue *q); typedef int (make_request_fn) (struct request_queue *q, struct bio *bio); typedef int (prep_rq_fn) (struct request_queue *, struct request *); typedef void (unplug_fn) (struct request_queue *); +typedef int (prepare_discard_fn) (struct request_queue *, struct request *); struct bio_vec; struct bvec_merge_data { @@ -307,6 +310,7 @@ struct request_queue make_request_fn *make_request_fn; prep_rq_fn *prep_rq_fn; unplug_fn *unplug_fn; + prepare_discard_fn *prepare_discard_fn; merge_bvec_fn *merge_bvec_fn; prepare_flush_fn *prepare_flush_fn; softirq_done_fn *softirq_done_fn; @@ -546,6 +550,7 @@ enum { #define blk_sorted_rq(rq) ((rq)->cmd_flags & REQ_SORTED) #define blk_barrier_rq(rq) ((rq)->cmd_flags & REQ_HARDBARRIER) #define blk_fua_rq(rq) ((rq)->cmd_flags & REQ_FUA) +#define blk_discard_rq(rq) ((rq)->cmd_flags & REQ_DISCARD) #define blk_bidi_rq(rq) ((rq)->next_rq != NULL) #define blk_empty_barrier(rq) (blk_barrier_rq(rq) && blk_fs_request(rq) && !(rq)->hard_nr_sectors) /* rq->queuelist of dequeued request must be list_empty() */ @@ -796,6 +801,7 @@ extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *); extern void blk_queue_dma_alignment(struct request_queue *, int); extern void blk_queue_update_dma_alignment(struct request_queue *, int); extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *); +extern void blk_queue_set_discard(struct request_queue *, prepare_discard_fn *); extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev); extern int blk_queue_ordered(struct request_queue *, unsigned, prepare_flush_fn *); extern int blk_do_ordered(struct request_queue *, struct request **); @@ -837,6 +843,16 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt, } extern int blkdev_issue_flush(struct block_device *, sector_t *); +extern int blkdev_issue_discard(struct block_device *, sector_t sector, + unsigned nr_sects); + +static inline int sb_issue_discard(struct super_block *sb, + sector_t block, unsigned nr_blocks) +{ + block <<= (sb->s_blocksize_bits - 9); + nr_blocks <<= (sb->s_blocksize_bits - 9); + return blkdev_issue_discard(sb->s_bdev, block, nr_blocks); +} /* * command filter functions diff --git a/include/linux/fs.h b/include/linux/fs.h index 580b513668fe..eb0131319134 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -86,7 +86,8 @@ extern int dir_notify_enable; #define READ_META (READ | (1 << BIO_RW_META)) #define WRITE_SYNC (WRITE | (1 << BIO_RW_SYNC)) #define SWRITE_SYNC (SWRITE | (1 << BIO_RW_SYNC)) -#define WRITE_BARRIER ((1 << BIO_RW) | (1 << BIO_RW_BARRIER)) +#define WRITE_BARRIER (WRITE | (1 << BIO_RW_BARRIER)) +#define WRITE_DISCARD (WRITE | (1 << BIO_RW_DISCARD)) #define SEL_IN 1 #define SEL_OUT 2 -- cgit v1.2.2