From: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx> The WRITE SAME command supported on some SCSI devices allows the same block to be efficiently replicated throughout a block range. Only a single logical block is transferred from the host and the storage device writes the same data to all blocks described by the I/O. This patch implements support for WRITE SAME in the block layer. The blkdev_issue_write_same() function can be used by filesystems and block drivers to replicate a buffer across a block range. This can be used to efficiently initialize software RAID devices, etc. Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Acked-by: Mike Snitzer <snitzer@xxxxxxxxxx> --- Documentation/ABI/testing/sysfs-block | 13 ++++++ block/blk-core.c | 14 +++++- block/blk-lib.c | 74 +++++++++++++++++++++++++++++++++ block/blk-settings.c | 16 +++++++ block/blk-sysfs.c | 13 ++++++ include/linux/bio.h | 3 + include/linux/blk_types.h | 7 ++- include/linux/blkdev.h | 16 +++++++ 8 files changed, 152 insertions(+), 4 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block index c1eb41c..02ed30c 100644 --- a/Documentation/ABI/testing/sysfs-block +++ b/Documentation/ABI/testing/sysfs-block @@ -206,3 +206,16 @@ Description: when a discarded area is read the discard_zeroes_data parameter will be set to one. Otherwise it will be 0 and the result of reading a discarded area is undefined. + +What: /sys/block/<disk>/queue/write_same_max_bytes +Date: January 2012 +Contact: Martin K. Petersen <martin.petersen@xxxxxxxxxx> +Description: + Some devices support a write same operation in which a + single data block can be written to a range of several + contiguous blocks on storage. This can be used to wipe + areas on disk or to initialize drives in a RAID + configuration. write_same_max_bytes indicates how many + bytes can be written in a single write same command. If + write_same_max_bytes is 0, write same is not supported + by the device. diff --git a/block/blk-core.c b/block/blk-core.c index 5575230..1cd55be 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1593,6 +1593,11 @@ generic_make_request_checks(struct bio *bio) goto end_io; } + if (bio->bi_rw & REQ_WRITE_SAME && !bdev_write_same(bio->bi_bdev)) { + err = -EOPNOTSUPP; + goto end_io; + } + if (blk_throtl_bio(q, bio)) return false; /* throttled, will be resubmitted later */ @@ -1690,8 +1695,6 @@ EXPORT_SYMBOL(generic_make_request); */ void submit_bio(int rw, struct bio *bio) { - int count = bio_sectors(bio); - bio->bi_rw |= rw; /* @@ -1699,6 +1702,13 @@ void submit_bio(int rw, struct bio *bio) * go through the normal accounting stuff before submission. */ if (bio_has_data(bio)) { + unsigned int count; + + if (unlikely(rw & REQ_WRITE_SAME)) + count = bdev_logical_block_size(bio->bi_bdev) >> 9; + else + count = bio_sectors(bio); + if (rw & WRITE) { count_vm_events(PGPGOUT, count); } else { diff --git a/block/blk-lib.c b/block/blk-lib.c index 2b461b4..e6cb5b4 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -115,6 +115,80 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, EXPORT_SYMBOL(blkdev_issue_discard); /** + * blkdev_issue_write_same - queue a write same operation + * @bdev: target blockdev + * @sector: start sector + * @nr_sects: number of sectors to write + * @gfp_mask: memory allocation flags (for bio_alloc) + * @page: page containing data to write + * + * Description: + * Issue a write same request for the sectors in question. + */ +int blkdev_issue_write_same(struct block_device *bdev, sector_t sector, + sector_t nr_sects, gfp_t gfp_mask, + struct page *page) +{ + DECLARE_COMPLETION_ONSTACK(wait); + struct request_queue *q = bdev_get_queue(bdev); + unsigned int max_write_same_sectors; + struct bio_batch bb; + struct bio *bio; + int ret = 0; + + if (!q) + return -ENXIO; + + max_write_same_sectors = q->limits.max_write_same_sectors; + + if (max_write_same_sectors == 0) + return -EOPNOTSUPP; + + atomic_set(&bb.done, 1); + bb.flags = 1 << BIO_UPTODATE; + bb.wait = &wait; + + while (nr_sects) { + bio = bio_alloc(gfp_mask, 1); + if (!bio) { + ret = -ENOMEM; + break; + } + + bio->bi_sector = sector; + bio->bi_end_io = bio_batch_end_io; + bio->bi_bdev = bdev; + bio->bi_private = &bb; + bio->bi_vcnt = 1; + bio->bi_io_vec->bv_page = page; + bio->bi_io_vec->bv_offset = 0; + bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev); + + if (nr_sects > max_write_same_sectors) { + bio->bi_size = max_write_same_sectors << 9; + nr_sects -= max_write_same_sectors; + sector += max_write_same_sectors; + } else { + bio->bi_size = nr_sects << 9; + nr_sects = 0; + } + + atomic_inc(&bb.done); + submit_bio(REQ_WRITE | REQ_WRITE_SAME, bio); + } + + /* Wait for bios in-flight */ + if (!atomic_dec_and_test(&bb.done)) + wait_for_completion(&wait); + + if (!test_bit(BIO_UPTODATE, &bb.flags)) + ret = -ENOTSUPP; + + return ret; +} +EXPORT_SYMBOL(blkdev_issue_write_same); + +/** * blkdev_issue_zeroout - generate number of zero filed write bios * @bdev: blockdev to issue * @sector: start sector diff --git a/block/blk-settings.c b/block/blk-settings.c index d3234fc..5680b91 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -113,6 +113,7 @@ void blk_set_default_limits(struct queue_limits *lim) lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; lim->max_segment_size = BLK_MAX_SEGMENT_SIZE; lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS; + lim->max_write_same_sectors = 0; lim->max_discard_sectors = 0; lim->discard_granularity = 0; lim->discard_alignment = 0; @@ -143,6 +144,7 @@ void blk_set_stacking_limits(struct queue_limits *lim) lim->discard_zeroes_data = 1; lim->max_segments = USHRT_MAX; lim->max_hw_sectors = UINT_MAX; + lim->max_write_same_sectors = UINT_MAX; lim->max_sectors = BLK_DEF_MAX_SECTORS; } @@ -287,6 +289,18 @@ void blk_queue_max_discard_sectors(struct request_queue *q, EXPORT_SYMBOL(blk_queue_max_discard_sectors); /** + * blk_queue_max_write_same_sectors - set max sectors for a single write same + * @q: the request queue for the device + * @max_write_same_sectors: maximum number of sectors to write per command + **/ +void blk_queue_max_write_same_sectors(struct request_queue *q, + unsigned int max_write_same_sectors) +{ + q->limits.max_write_same_sectors = max_write_same_sectors; +} +EXPORT_SYMBOL(blk_queue_max_write_same_sectors); + +/** * blk_queue_max_segments - set max hw segments for a request for this queue * @q: the request queue for the device * @max_segments: max number of segments @@ -511,6 +525,8 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); + t->max_write_same_sectors = min(t->max_write_same_sectors, + b->max_write_same_sectors); t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn); t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index cf15001..5b85d91 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -161,6 +161,13 @@ static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *pag return queue_var_show(queue_discard_zeroes_data(q), page); } +static ssize_t queue_write_same_max_show(struct request_queue *q, char *page) +{ + return sprintf(page, "%llu\n", + (unsigned long long)q->limits.max_write_same_sectors << 9); +} + + static ssize_t queue_max_sectors_store(struct request_queue *q, const char *page, size_t count) { @@ -357,6 +364,11 @@ static struct queue_sysfs_entry queue_discard_zeroes_data_entry = { .show = queue_discard_zeroes_data_show, }; +static struct queue_sysfs_entry queue_write_same_max_entry = { + .attr = {.name = "write_same_max_bytes", .mode = S_IRUGO }, + .show = queue_write_same_max_show, +}; + static struct queue_sysfs_entry queue_nonrot_entry = { .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR }, .show = queue_show_nonrot, @@ -404,6 +416,7 @@ static struct attribute *default_attrs[] = { &queue_discard_granularity_entry.attr, &queue_discard_max_entry.attr, &queue_discard_zeroes_data_entry.attr, + &queue_write_same_max_entry.attr, &queue_nonrot_entry.attr, &queue_nomerges_entry.attr, &queue_rq_affinity_entry.attr, diff --git a/include/linux/bio.h b/include/linux/bio.h index cad2a9c..df4b91e 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -371,6 +371,9 @@ static inline bool bio_is_rw(struct bio *bio) if (!bio_has_data(bio)) return false; + if (bio->bi_rw & REQ_WRITE_SAME) + return false; + return true; } diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 1a2727c..ac1e03e 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -124,6 +124,7 @@ enum rq_flag_bits { __REQ_PRIO, /* boost priority in cfq */ __REQ_DISCARD, /* request to discard sectors */ __REQ_SECURE, /* secure discard (used with __REQ_DISCARD) */ + __REQ_WRITE_SAME, /* write same block many times */ __REQ_NOIDLE, /* don't anticipate more IO after this one */ __REQ_FUA, /* forced unit access */ @@ -162,17 +163,19 @@ enum rq_flag_bits { #define REQ_PRIO (1 << __REQ_PRIO) #define REQ_DISCARD (1 << __REQ_DISCARD) #define REQ_NOIDLE (1 << __REQ_NOIDLE) +#define REQ_WRITE_SAME (1 << __REQ_WRITE_SAME) #define REQ_FAILFAST_MASK \ (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER) #define REQ_COMMON_MASK \ (REQ_WRITE | REQ_FAILFAST_MASK | REQ_SYNC | REQ_META | REQ_PRIO | \ - REQ_DISCARD | REQ_NOIDLE | REQ_FLUSH | REQ_FUA | REQ_SECURE) + REQ_DISCARD | REQ_WRITE_SAME | REQ_NOIDLE | REQ_FLUSH | REQ_FUA | \ + REQ_SECURE) #define REQ_CLONE_MASK REQ_COMMON_MASK #define REQ_NOMERGE_FLAGS \ (REQ_NOMERGE | REQ_STARTED | REQ_SOFTBARRIER | REQ_FLUSH | REQ_FUA | \ - REQ_DISCARD) + REQ_DISCARD | REQ_WRITE_SAME) #define REQ_RAHEAD (1 << __REQ_RAHEAD) #define REQ_THROTTLED (1 << __REQ_THROTTLED) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 3943933..8c97ee9 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -254,6 +254,7 @@ struct queue_limits { unsigned int io_min; unsigned int io_opt; unsigned int max_discard_sectors; + unsigned int max_write_same_sectors; unsigned int discard_granularity; unsigned int discard_alignment; @@ -831,6 +832,8 @@ extern void blk_queue_max_segments(struct request_queue *, unsigned short); extern void blk_queue_max_segment_size(struct request_queue *, unsigned int); extern void blk_queue_max_discard_sectors(struct request_queue *q, unsigned int max_discard_sectors); +extern void blk_queue_max_write_same_sectors(struct request_queue *q, + unsigned int max_write_same_sectors); extern void blk_queue_logical_block_size(struct request_queue *, unsigned short); extern void blk_queue_physical_block_size(struct request_queue *, unsigned int); extern void blk_queue_alignment_offset(struct request_queue *q, @@ -955,6 +958,9 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt, extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *); extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp_mask, unsigned long flags); +extern int blkdev_issue_write_same(struct block_device *bdev, sector_t sector, + sector_t nr_sects, gfp_t gfp_mask, void *buffer, + unsigned int length); extern int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp_mask); static inline int sb_issue_discard(struct super_block *sb, sector_t block, @@ -1122,6 +1128,16 @@ static inline unsigned int bdev_discard_zeroes_data(struct block_device *bdev) return queue_discard_zeroes_data(bdev_get_queue(bdev)); } +static inline unsigned int bdev_write_same(struct block_device *bdev) +{ + struct request_queue *q = bdev_get_queue(bdev); + + if (q) + return q->limits.max_write_same_sectors; + + return 0; +} + static inline int queue_dma_alignment(struct request_queue *q) { return q ? q->dma_alignment : 511; -- 1.7.8.3.21.gab8a7 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html