From: Mike Christie <[email protected]> This patch adds block layer helpers to send a compare and write request. It differs from requests like discard and write same in that there is a setup function and a issue one. I did this to allow callers add multiple pages with variying offsets and lengths.
For the miscompare failure case I am currently having drivers return -ECANCELED, but was not sure if there is a better return code. Signed-off-by: Mike Christie <[email protected]> --- block/blk-lib.c | 79 +++++++++++++++++++++++++++++++++++++++++++++ include/linux/blk_types.h | 6 ++- include/linux/blkdev.h | 6 +++ 3 files changed, 89 insertions(+), 2 deletions(-) diff --git a/block/blk-lib.c b/block/blk-lib.c index 8411be3..fbb1a91 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -141,6 +141,85 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, } EXPORT_SYMBOL(blkdev_issue_discard); +struct bio_cmp_and_write_data { + int err; + struct completion *wait; +}; + +static void bio_cmp_and_write_end_io(struct bio *bio, int err) +{ + struct bio_cmp_and_write_data *data = bio->bi_private; + + data->err = err; + complete(data->wait); + bio_put(bio); +} + +/** + * blkdev_setup_cmp_and_write - setup a bio for a compare and write operation + * @bdev: blockdev to issue discard for + * @sector: start sector + * @gfp_mask: memory allocation flags (for bio_alloc) + * @nr_pages: number of pages that contain the data to be written and compared + * + * This function should be called to allocate the bio used for + * blkdev_issue_cmp_and_write. The caller should add the pages to be compared + * followed by the write pages using bio_add_pc_page. + */ +struct bio *blkdev_setup_cmp_and_write(struct block_device *bdev, + sector_t sector, gfp_t gfp_mask, + int nr_pages) +{ + struct bio *bio; + + bio = bio_alloc(gfp_mask, nr_pages); + if (!bio) + return NULL; + + bio->bi_iter.bi_sector = sector; + bio->bi_end_io = bio_cmp_and_write_end_io; + bio->bi_bdev = bdev; + return bio; +} +EXPORT_SYMBOL(blkdev_setup_cmp_and_write); + +/** + * blkdev_issue_cmp_and_write - queue a compare and write operation + * @bio: bio prepd with blkdev_setup_cmp_and_write. + * Description: + * Issue a compare and write bio for the sectors in question. For the + * execution of this request the handler should atomically read @nr_sects + * from starting sector @sector, compare them, and if matched write + * @nr_sects to @sector. + * + * If the compare fails and data is not written the handler should return + * -ECANCELED. + */ +int blkdev_issue_cmp_and_write(struct bio *bio) +{ + struct request_queue *q = bdev_get_queue(bio->bi_bdev); + DECLARE_COMPLETION_ONSTACK(wait); + struct bio_cmp_and_write_data data; + unsigned int max_cmp_and_write_sectors; + + max_cmp_and_write_sectors = q->limits.max_cmp_and_write_sectors; + if (max_cmp_and_write_sectors == 0) + return -EOPNOTSUPP; + + if (max_cmp_and_write_sectors < bio->bi_iter.bi_size >> 9) + return -EINVAL; + + data.err = 0; + data.wait = &wait; + bio->bi_private = &data; + + submit_bio(REQ_WRITE | REQ_CMP_AND_WRITE, bio); + /* Wait for bio in-flight */ + wait_for_completion_io(&wait); + return data.err; +} +EXPORT_SYMBOL(blkdev_issue_cmp_and_write); + /** * blkdev_issue_write_same - queue a write same operation * @bdev: target blockdev diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 66c2167..37d1eff 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -160,7 +160,7 @@ enum rq_flag_bits { __REQ_DISCARD, /* request to discard sectors */ __REQ_SECURE, /* secure discard (used with __REQ_DISCARD) */ __REQ_WRITE_SAME, /* write same block many times */ - + __REQ_CMP_AND_WRITE, /* compare data and write if matched */ __REQ_NOIDLE, /* don't anticipate more IO after this one */ __REQ_FUA, /* forced unit access */ __REQ_FLUSH, /* request for cache flush */ @@ -203,14 +203,16 @@ enum rq_flag_bits { #define REQ_PRIO (1ULL << __REQ_PRIO) #define REQ_DISCARD (1ULL << __REQ_DISCARD) #define REQ_WRITE_SAME (1ULL << __REQ_WRITE_SAME) +#define REQ_CMP_AND_WRITE (1ULL << __REQ_CMP_AND_WRITE) #define REQ_NOIDLE (1ULL << __REQ_NOIDLE) + #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_WRITE_SAME | REQ_NOIDLE | REQ_FLUSH | REQ_FUA | \ - REQ_SECURE) + REQ_SECURE | REQ_CMP_AND_WRITE) #define REQ_CLONE_MASK REQ_COMMON_MASK #define BIO_NO_ADVANCE_ITER_MASK (REQ_DISCARD|REQ_WRITE_SAME) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 6d03206..746d5b4 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -696,6 +696,9 @@ static inline bool blk_check_merge_flags(unsigned int flags1, if ((flags1 & REQ_WRITE_SAME) != (flags2 & REQ_WRITE_SAME)) return false; + if (flags1 & REQ_CMP_AND_WRITE || flags2 & REQ_CMP_AND_WRITE) + return false; + return true; } @@ -1167,6 +1170,9 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt, #define BLKDEV_DISCARD_SECURE 0x01 /* secure discard */ +extern struct bio *blkdev_setup_cmp_and_write(struct block_device *, sector_t, + gfp_t, int); +extern int blkdev_issue_cmp_and_write(struct bio *bio); 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); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
