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green245.sa.corp.samsungelectronics.net (unknown [107.99.41.245]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20231222062112epsmtip24391c108c8dd8663d9345d5960bcf949~jExawUa6O0303903039epsmtip2a; Fri, 22 Dec 2023 06:21:12 +0000 (GMT) From: Nitesh Shetty To: Jens Axboe , Jonathan Corbet , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , dm-devel@lists.linux.dev, Keith Busch , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , Alexander Viro , Christian Brauner Cc: martin.petersen@oracle.com, linux-scsi@vger.kernel.org, nitheshshetty@gmail.com, anuj1072538@gmail.com, gost.dev@samsung.com, mcgrof@kernel.org, Nitesh Shetty , Hannes Reinecke , Anuj Gupta , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org Subject: [PATCH v19 03/12] block: add copy offload support Date: Fri, 22 Dec 2023 11:42:57 +0530 Message-Id: <20231222061313.12260-4-nj.shetty@samsung.com> X-Mailer: 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20231222062116epcas5p2ff54b405039a65f107b2a570b113c501 X-Msg-Generator: CA X-Sendblock-Type: REQ_APPROVE CMS-TYPE: 105P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20231222062116epcas5p2ff54b405039a65f107b2a570b113c501 References: <20231222061313.12260-1-nj.shetty@samsung.com> Introduce blkdev_copy_offload to perform copy offload. Issue REQ_OP_COPY_DST with destination info along with taking a plug. This flows till request layer and waits for src bio to arrive. Issue REQ_OP_COPY_SRC with source info and this bio reaches request layer and merges with dst request. For any reason, if a request comes to the driver with only one of src/dst bio, we fail the copy offload. Larger copy will be divided, based on max_copy_sectors limit. Reviewed-by: Hannes Reinecke Signed-off-by: Anuj Gupta Signed-off-by: Nitesh Shetty --- block/blk-lib.c | 204 +++++++++++++++++++++++++++++++++++++++++ include/linux/blkdev.h | 4 + 2 files changed, 208 insertions(+) diff --git a/block/blk-lib.c b/block/blk-lib.c index e59c3069e835..f03cb4bc3134 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -10,6 +10,22 @@ #include "blk.h" +/* Keeps track of all outstanding copy IO */ +struct blkdev_copy_io { + atomic_t refcount; + ssize_t copied; + int status; + struct task_struct *waiter; + void (*endio)(void *private, int status, ssize_t copied); + void *private; +}; + +/* Keeps track of single outstanding copy offload IO */ +struct blkdev_copy_offload_io { + struct blkdev_copy_io *cio; + loff_t offset; +}; + static sector_t bio_discard_limit(struct block_device *bdev, sector_t sector) { unsigned int discard_granularity = bdev_discard_granularity(bdev); @@ -115,6 +131,194 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, } EXPORT_SYMBOL(blkdev_issue_discard); +static inline ssize_t blkdev_copy_sanity_check(struct block_device *bdev_in, + loff_t pos_in, + struct block_device *bdev_out, + loff_t pos_out, size_t len) +{ + unsigned int align = max(bdev_logical_block_size(bdev_out), + bdev_logical_block_size(bdev_in)) - 1; + + if ((pos_in & align) || (pos_out & align) || (len & align) || !len || + len >= BLK_COPY_MAX_BYTES) + return -EINVAL; + + return 0; +} + +static inline void blkdev_copy_endio(struct blkdev_copy_io *cio) +{ + if (cio->endio) { + cio->endio(cio->private, cio->status, cio->copied); + kfree(cio); + } else { + struct task_struct *waiter = cio->waiter; + + WRITE_ONCE(cio->waiter, NULL); + blk_wake_io_task(waiter); + } +} + +/* + * This must only be called once all bios have been issued so that the refcount + * can only decrease. This just waits for all bios to complete. + * Returns the length of bytes copied or error + */ +static ssize_t blkdev_copy_wait_for_completion_io(struct blkdev_copy_io *cio) +{ + ssize_t ret; + + for (;;) { + __set_current_state(TASK_UNINTERRUPTIBLE); + if (!READ_ONCE(cio->waiter)) + break; + blk_io_schedule(); + } + __set_current_state(TASK_RUNNING); + ret = cio->copied; + kfree(cio); + + return ret; +} + +static void blkdev_copy_offload_src_endio(struct bio *bio) +{ + struct blkdev_copy_offload_io *offload_io = bio->bi_private; + struct blkdev_copy_io *cio = offload_io->cio; + + if (bio->bi_status) { + cio->copied = min_t(ssize_t, offload_io->offset, cio->copied); + if (!cio->status) + cio->status = blk_status_to_errno(bio->bi_status); + } + bio_put(bio); + kfree(offload_io); + + if (atomic_dec_and_test(&cio->refcount)) + blkdev_copy_endio(cio); +} + +/* + * @bdev: block device + * @pos_in: source offset + * @pos_out: destination offset + * @len: length in bytes to be copied + * @endio: endio function to be called on completion of copy operation, + * for synchronous operation this should be NULL + * @private: endio function will be called with this private data, + * for synchronous operation this should be NULL + * @gfp_mask: memory allocation flags (for bio_alloc) + * + * For synchronous operation returns the length of bytes copied or error + * For asynchronous operation returns -EIOCBQUEUED or error + * + * Description: + * Copy source offset to destination offset within block device, using + * device's native copy offload feature. + * We perform copy operation using 2 bio's. + * 1. We take a plug and send a REQ_OP_COPY_DST bio along with destination + * sector and length. Once this bio reaches request layer, we form a + * request and wait for dst bio to arrive. + * 2. We issue REQ_OP_COPY_SRC bio along with source sector, length. + * Once this bio reaches request layer and find a request with previously + * sent destination info we merge the source bio and return. + * 3. Release the plug and request is sent to driver + * This design works only for drivers with request queue. + */ +ssize_t blkdev_copy_offload(struct block_device *bdev, loff_t pos_in, + loff_t pos_out, size_t len, + void (*endio)(void *, int, ssize_t), + void *private, gfp_t gfp) +{ + struct blkdev_copy_io *cio; + struct blkdev_copy_offload_io *offload_io; + struct bio *src_bio, *dst_bio; + size_t rem, chunk; + size_t max_copy_bytes = bdev_max_copy_sectors(bdev) << SECTOR_SHIFT; + ssize_t ret; + struct blk_plug plug; + + if (!max_copy_bytes) + return -EOPNOTSUPP; + + ret = blkdev_copy_sanity_check(bdev, pos_in, bdev, pos_out, len); + if (ret) + return ret; + + cio = kzalloc(sizeof(*cio), gfp); + if (!cio) + return -ENOMEM; + atomic_set(&cio->refcount, 1); + cio->waiter = current; + cio->endio = endio; + cio->private = private; + + /* + * If there is a error, copied will be set to least successfully + * completed copied length + */ + cio->copied = len; + for (rem = len; rem > 0; rem -= chunk) { + chunk = min(rem, max_copy_bytes); + + offload_io = kzalloc(sizeof(*offload_io), gfp); + if (!offload_io) + goto err_free_cio; + offload_io->cio = cio; + /* + * For partial completion, we use offload_io->offset to truncate + * successful copy length + */ + offload_io->offset = len - rem; + + dst_bio = bio_alloc(bdev, 0, REQ_OP_COPY_DST, gfp); + if (!dst_bio) + goto err_free_offload_io; + dst_bio->bi_iter.bi_size = chunk; + dst_bio->bi_iter.bi_sector = pos_out >> SECTOR_SHIFT; + + blk_start_plug(&plug); + src_bio = blk_next_bio(dst_bio, bdev, 0, REQ_OP_COPY_SRC, gfp); + if (!src_bio) + goto err_free_dst_bio; + src_bio->bi_iter.bi_size = chunk; + src_bio->bi_iter.bi_sector = pos_in >> SECTOR_SHIFT; + src_bio->bi_end_io = blkdev_copy_offload_src_endio; + src_bio->bi_private = offload_io; + + atomic_inc(&cio->refcount); + submit_bio(src_bio); + blk_finish_plug(&plug); + pos_in += chunk; + pos_out += chunk; + } + + if (atomic_dec_and_test(&cio->refcount)) + blkdev_copy_endio(cio); + if (endio) + return -EIOCBQUEUED; + + return blkdev_copy_wait_for_completion_io(cio); + +err_free_dst_bio: + bio_put(dst_bio); +err_free_offload_io: + kfree(offload_io); +err_free_cio: + cio->copied = min_t(ssize_t, cio->copied, (len - rem)); + cio->status = -ENOMEM; + if (rem == len) { + ret = cio->status; + kfree(cio); + return ret; + } + if (cio->endio) + return cio->status; + + return blkdev_copy_wait_for_completion_io(cio); +} +EXPORT_SYMBOL_GPL(blkdev_copy_offload); + static int __blkdev_issue_write_zeroes(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp_mask, struct bio **biop, unsigned flags) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index d5019967a908..cd940de16750 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1042,6 +1042,10 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp_mask, struct bio **biop); int blkdev_issue_secure_erase(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp); +ssize_t blkdev_copy_offload(struct block_device *bdev, loff_t pos_in, + loff_t pos_out, size_t len, + void (*endio)(void *, int, ssize_t), + void *private, gfp_t gfp_mask); #define BLKDEV_ZERO_NOUNMAP (1 << 0) /* do not free blocks */ #define BLKDEV_ZERO_NOFALLBACK (1 << 1) /* don't write explicit zeroes */