For the devices which does not support copy, copy emulation is added. It is required for in-kernel users like fabrics, where file descriptor is not available and hence they can't use copy_file_range. Copy-emulation is implemented by reading from source into memory and writing to the corresponding destination. At present in kernel user of emulation is fabrics. Signed-off-by: Nitesh Shetty <nj.shetty@xxxxxxxxxxx> Signed-off-by: Vincent Fu <vincent.fu@xxxxxxxxxxx> Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx> --- block/blk-lib.c | 223 +++++++++++++++++++++++++++++++++++++++++ include/linux/blkdev.h | 4 + 2 files changed, 227 insertions(+) diff --git a/block/blk-lib.c b/block/blk-lib.c index 50d10fa3c4c5..da3594d25a3f 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -26,6 +26,20 @@ struct blkdev_copy_offload_io { loff_t offset; }; +/* Keeps track of single outstanding copy emulation IO */ +struct blkdev_copy_emulation_io { + struct blkdev_copy_io *cio; + struct work_struct emulation_work; + void *buf; + ssize_t buf_len; + loff_t pos_in; + loff_t pos_out; + ssize_t len; + struct block_device *bdev_in; + struct block_device *bdev_out; + gfp_t gfp; +}; + static sector_t bio_discard_limit(struct block_device *bdev, sector_t sector) { unsigned int discard_granularity = bdev_discard_granularity(bdev); @@ -316,6 +330,215 @@ ssize_t blkdev_copy_offload(struct block_device *bdev, loff_t pos_in, } EXPORT_SYMBOL_GPL(blkdev_copy_offload); +static void *blkdev_copy_alloc_buf(ssize_t req_size, ssize_t *alloc_size, + gfp_t gfp) +{ + int min_size = PAGE_SIZE; + char *buf; + + while (req_size >= min_size) { + buf = kvmalloc(req_size, gfp); + if (buf) { + *alloc_size = req_size; + return buf; + } + req_size >>= 1; + } + + return NULL; +} + +static struct bio *bio_map_buf(void *data, unsigned int len, gfp_t gfp) +{ + unsigned long kaddr = (unsigned long)data; + unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT; + unsigned long start = kaddr >> PAGE_SHIFT; + const int nr_pages = end - start; + bool is_vmalloc = is_vmalloc_addr(data); + struct page *page; + int offset, i; + struct bio *bio; + + bio = bio_kmalloc(nr_pages, gfp); + if (!bio) + return ERR_PTR(-ENOMEM); + bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, 0); + + if (is_vmalloc) { + flush_kernel_vmap_range(data, len); + bio->bi_private = data; + } + + offset = offset_in_page(kaddr); + for (i = 0; i < nr_pages; i++) { + unsigned int bytes = PAGE_SIZE - offset; + + if (len <= 0) + break; + + if (bytes > len) + bytes = len; + + if (!is_vmalloc) + page = virt_to_page(data); + else + page = vmalloc_to_page(data); + if (bio_add_page(bio, page, bytes, offset) < bytes) { + /* we don't support partial mappings */ + bio_uninit(bio); + kfree(bio); + return ERR_PTR(-EINVAL); + } + + data += bytes; + len -= bytes; + offset = 0; + } + + return bio; +} + +static void blkdev_copy_emulation_work(struct work_struct *work) +{ + struct blkdev_copy_emulation_io *emulation_io = container_of(work, + struct blkdev_copy_emulation_io, emulation_work); + struct blkdev_copy_io *cio = emulation_io->cio; + struct bio *read_bio, *write_bio; + loff_t pos_in = emulation_io->pos_in, pos_out = emulation_io->pos_out; + ssize_t rem, chunk; + int ret = 0; + + for (rem = emulation_io->len; rem > 0; rem -= chunk) { + chunk = min_t(int, emulation_io->buf_len, rem); + + read_bio = bio_map_buf(emulation_io->buf, + emulation_io->buf_len, + emulation_io->gfp); + if (IS_ERR(read_bio)) { + ret = PTR_ERR(read_bio); + break; + } + read_bio->bi_opf = REQ_OP_READ | REQ_SYNC; + bio_set_dev(read_bio, emulation_io->bdev_in); + read_bio->bi_iter.bi_sector = pos_in >> SECTOR_SHIFT; + read_bio->bi_iter.bi_size = chunk; + ret = submit_bio_wait(read_bio); + kfree(read_bio); + if (ret) + break; + + write_bio = bio_map_buf(emulation_io->buf, + emulation_io->buf_len, + emulation_io->gfp); + if (IS_ERR(write_bio)) { + ret = PTR_ERR(write_bio); + break; + } + write_bio->bi_opf = REQ_OP_WRITE | REQ_SYNC; + bio_set_dev(write_bio, emulation_io->bdev_out); + write_bio->bi_iter.bi_sector = pos_out >> SECTOR_SHIFT; + write_bio->bi_iter.bi_size = chunk; + ret = submit_bio_wait(write_bio); + kfree(write_bio); + if (ret) + break; + + pos_in += chunk; + pos_out += chunk; + } + cio->status = ret; + kvfree(emulation_io->buf); + kfree(emulation_io); + blkdev_copy_endio(cio); +} + +static inline ssize_t queue_max_hw_bytes(struct request_queue *q) +{ + return min_t(ssize_t, queue_max_hw_sectors(q) << SECTOR_SHIFT, + queue_max_segments(q) << PAGE_SHIFT); +} +/* + * @bdev_in: source block device + * @pos_in: source offset + * @bdev_out: destination block device + * @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: + * If native copy offload feature is absent, caller can use this function + * to perform copy. + * We store information required to perform the copy along with temporary + * buffer allocation. We async punt copy emulation to a worker. And worker + * performs copy in 2 steps. + * 1. Read data from source to temporary buffer + * 2. Write data to destination from temporary buffer + */ +ssize_t blkdev_copy_emulation(struct block_device *bdev_in, loff_t pos_in, + struct block_device *bdev_out, loff_t pos_out, + size_t len, void (*endio)(void *, int, ssize_t), + void *private, gfp_t gfp) +{ + struct request_queue *in = bdev_get_queue(bdev_in); + struct request_queue *out = bdev_get_queue(bdev_out); + struct blkdev_copy_emulation_io *emulation_io; + struct blkdev_copy_io *cio; + ssize_t ret; + size_t max_hw_bytes = min(queue_max_hw_bytes(in), + queue_max_hw_bytes(out)); + + ret = blkdev_copy_sanity_check(bdev_in, pos_in, bdev_out, pos_out, len); + if (ret) + return ret; + + cio = kzalloc(sizeof(*cio), GFP_KERNEL); + if (!cio) + return -ENOMEM; + + cio->waiter = current; + cio->copied = len; + cio->endio = endio; + cio->private = private; + + emulation_io = kzalloc(sizeof(*emulation_io), gfp); + if (!emulation_io) + goto err_free_cio; + emulation_io->cio = cio; + INIT_WORK(&emulation_io->emulation_work, blkdev_copy_emulation_work); + emulation_io->pos_in = pos_in; + emulation_io->pos_out = pos_out; + emulation_io->len = len; + emulation_io->bdev_in = bdev_in; + emulation_io->bdev_out = bdev_out; + emulation_io->gfp = gfp; + + emulation_io->buf = blkdev_copy_alloc_buf(min(max_hw_bytes, len), + &emulation_io->buf_len, gfp); + if (!emulation_io->buf) + goto err_free_emulation_io; + + schedule_work(&emulation_io->emulation_work); + + if (cio->endio) + return -EIOCBQUEUED; + + return blkdev_copy_wait_io_completion(cio); + +err_free_emulation_io: + kfree(emulation_io); +err_free_cio: + kfree(cio); + return -ENOMEM; +} +EXPORT_SYMBOL_GPL(blkdev_copy_emulation); + 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 5405499bcf22..e0a832a1c3a7 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1046,6 +1046,10 @@ 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); +ssize_t blkdev_copy_emulation(struct block_device *bdev_in, loff_t pos_in, + struct block_device *bdev_out, loff_t pos_out, + size_t len, void (*endio)(void *, int, ssize_t), + void *private, gfp_t gfp); #define BLKDEV_ZERO_NOUNMAP (1 << 0) /* do not free blocks */ #define BLKDEV_ZERO_NOFALLBACK (1 << 1) /* don't write explicit zeroes */ -- 2.35.1.500.gb896f729e2