Re: [RFC PATCH v4 2/3] block: add simple copy support
From: Selva Jove
Date: Tue Jan 05 2021 - 07:26:54 EST
Thanks for the review, Damien.
On Mon, Jan 4, 2021 at 6:17 PM Damien Le Moal <Damien.LeMoal@xxxxxxx> wrote:
>
> On 2021/01/04 19:48, SelvaKumar S wrote:
> > Add new BLKCOPY ioctl that offloads copying of one or more sources
> > ranges to a destination in the device. Accepts copy_ranges that contains
> > destination, no of sources and pointer to the array of source
> > ranges. Each range_entry contains start and length of source
> > ranges (in bytes).
> >
> > Introduce REQ_OP_COPY, a no-merge copy offload operation. Create
> > bio with control information as payload and submit to the device.
> > REQ_OP_COPY(19) is a write op and takes zone_write_lock when submitted
> > to zoned device.
> >
> > If the device doesn't support copy or copy offload is disabled, then
> > copy is emulated by allocating memory of total copy size. The source
> > ranges are read into memory by chaining bio for each source ranges and
> > submitting them async and the last bio waits for completion. After data
> > is read, it is written to the destination.
> >
> > bio_map_kern() is used to allocate bio and add pages of copy buffer to
> > bio. As bio->bi_private and bio->bi_end_io is needed for chaining the
> > bio and over written, invalidate_kernel_vmap_range() for read is called
> > in the caller.
> >
> > Introduce queue limits for simple copy and other helper functions.
> > Add device limits as sysfs entries.
> > - copy_offload
> > - max_copy_sectors
> > - max_copy_ranges_sectors
> > - max_copy_nr_ranges
> >
> > copy_offload(= 0) is disabled by default.
> > max_copy_sectors = 0 indicates the device doesn't support native copy.
> >
> > Native copy offload is not supported for stacked devices and is done via
> > copy emulation.
> >
> > Signed-off-by: SelvaKumar S <selvakuma.s1@xxxxxxxxxxx>
> > Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx>
> > Signed-off-by: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>
> > Signed-off-by: Javier González <javier.gonz@xxxxxxxxxxx>
> > ---
> > block/blk-core.c | 94 ++++++++++++++--
> > block/blk-lib.c | 223 ++++++++++++++++++++++++++++++++++++++
> > block/blk-merge.c | 2 +
> > block/blk-settings.c | 10 ++
> > block/blk-sysfs.c | 50 +++++++++
> > block/blk-zoned.c | 1 +
> > block/bounce.c | 1 +
> > block/ioctl.c | 43 ++++++++
> > include/linux/bio.h | 1 +
> > include/linux/blk_types.h | 15 +++
> > include/linux/blkdev.h | 13 +++
> > include/uapi/linux/fs.h | 13 +++
> > 12 files changed, 458 insertions(+), 8 deletions(-)
> >
> > diff --git a/block/blk-core.c b/block/blk-core.c
> > index 96e5fcd7f071..4a5cd3f53cd2 100644
> > --- a/block/blk-core.c
> > +++ b/block/blk-core.c
> > @@ -719,6 +719,17 @@ static noinline int should_fail_bio(struct bio *bio)
> > }
> > ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO);
> >
> > +static inline int bio_check_copy_eod(struct bio *bio, sector_t start,
> > + sector_t nr_sectors, sector_t maxsector)
> > +{
> > + if (nr_sectors && maxsector &&
> > + (nr_sectors > maxsector || start > maxsector - nr_sectors)) {
> > + handle_bad_sector(bio, maxsector);
> > + return -EIO;
> > + }
> > + return 0;
> > +}
> > +
> > /*
> > * Check whether this bio extends beyond the end of the device or partition.
> > * This may well happen - the kernel calls bread() without checking the size of
> > @@ -737,6 +748,65 @@ static inline int bio_check_eod(struct bio *bio, sector_t maxsector)
> > return 0;
> > }
> >
> > +/*
> > + * Check for copy limits and remap source ranges if needed.
> > + */
> > +static int blk_check_copy(struct bio *bio)
> > +{
> > + struct block_device *p = NULL;
> > + struct request_queue *q = bio->bi_disk->queue;
> > + struct blk_copy_payload *payload;
> > + int i, maxsector, start_sect = 0, ret = -EIO;
> > + unsigned short nr_range;
> > +
> > + rcu_read_lock();
> > +
> > + p = __disk_get_part(bio->bi_disk, bio->bi_partno);
> > + if (unlikely(!p))
> > + goto out;
> > + if (unlikely(should_fail_request(p, bio->bi_iter.bi_size)))
> > + goto out;
> > + if (unlikely(bio_check_ro(bio, p)))
> > + goto out;
> > +
> > + maxsector = bdev_nr_sectors(p);
> > + start_sect = p->bd_start_sect;
> > +
> > + payload = bio_data(bio);
> > + nr_range = payload->copy_range;
> > +
> > + /* cannot handle copy crossing nr_ranges limit */
> > + if (payload->copy_range > q->limits.max_copy_nr_ranges)
> > + goto out;
>
> If payload->copy_range indicates the number of ranges to be copied, you should
> name it payload->copy_nr_ranges.
>
Agreed. Will rename the entries.
> > +
> > + /* cannot handle copy more than copy limits */
>
> Why ? You could loop... Similarly to discard, zone reset etc.
>
Sure. Will add the support for handling copy larger than device limits.
>
> > + if (payload->copy_size > q->limits.max_copy_sectors)
> > + goto out;
>
> Shouldn't the list of source ranges give the total size to be copied ?
> Otherwise, if payload->copy_size is user provided, you would need to check that
> the sum of the source ranges actually is equal to copy_size, no ? That means
> that dropping copy_size sound like the right thing to do here.
>
payload->copy_size is used in copy emulation to allocate the buffer.
Let me check
one more time if it is possible to do without this.
> > +
> > + /* check if copy length crosses eod */
> > + if (unlikely(bio_check_copy_eod(bio, bio->bi_iter.bi_sector,
> > + payload->copy_size, maxsector)))
> > + goto out;
> > + bio->bi_iter.bi_sector += start_sect;
> > +
> > + for (i = 0; i < nr_range; i++) {
> > + if (unlikely(bio_check_copy_eod(bio, payload->range[i].src,
> > + payload->range[i].len, maxsector)))
> > + goto out;
> > +
> > + /* single source range length limit */
> > + if (payload->range[i].src > q->limits.max_copy_range_sectors)
> > + goto out;
> > + payload->range[i].src += start_sect;
> > + }
> > +
> > + bio->bi_partno = 0;
> > + ret = 0;
> > +out:
> > + rcu_read_unlock();
> > + return ret;
> > +}
> > +
> > /*
> > * Remap block n of partition p to block n+start(p) of the disk.
> > */
> > @@ -826,14 +896,16 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio)
> > if (should_fail_bio(bio))
> > goto end_io;
> >
> > - if (bio->bi_partno) {
> > - if (unlikely(blk_partition_remap(bio)))
> > - goto end_io;
> > - } else {
> > - if (unlikely(bio_check_ro(bio, bio->bi_disk->part0)))
> > - goto end_io;
> > - if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk))))
> > - goto end_io;
> > + if (likely(!op_is_copy(bio->bi_opf))) {
> > + if (bio->bi_partno) {
> > + if (unlikely(blk_partition_remap(bio)))
> > + goto end_io;
> > + } else {
> > + if (unlikely(bio_check_ro(bio, bio->bi_disk->part0)))
> > + goto end_io;
> > + if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk))))
> > + goto end_io;
> > + }
> > }
> >
> > /*
> > @@ -857,6 +929,12 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio)
> > if (!blk_queue_discard(q))
> > goto not_supported;
> > break;
> > + case REQ_OP_COPY:
> > + if (!blk_queue_copy(q))
> > + goto not_supported;
>
> This check could be inside blk_check_copy(). In any case, since you added the
> read-write emulation, why are you even checking this ? That will prevent the use
> of the read-write emulation for devices that lack the simple copy support, no ?
>
Makes sense. Will remove this check.
>
> > + if (unlikely(blk_check_copy(bio)))
> > + goto end_io;
> > + break;
> > case REQ_OP_SECURE_ERASE:
> > if (!blk_queue_secure_erase(q))
> > goto not_supported;
> > diff --git a/block/blk-lib.c b/block/blk-lib.c
> > index 752f9c722062..4c0f12e2ed7c 100644
> > --- a/block/blk-lib.c
> > +++ b/block/blk-lib.c
> > @@ -150,6 +150,229 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
> > }
> > EXPORT_SYMBOL(blkdev_issue_discard);
> >
> > +int blk_copy_offload(struct block_device *bdev, struct blk_copy_payload *payload,
> > + sector_t dest, gfp_t gfp_mask)
> > +{
> > + struct bio *bio;
> > + int ret, total_size;
> > +
> > + bio = bio_alloc(gfp_mask, 1);
> > + bio->bi_iter.bi_sector = dest;
> > + bio->bi_opf = REQ_OP_COPY | REQ_NOMERGE;
> > + bio_set_dev(bio, bdev);
> > +
> > + total_size = struct_size(payload, range, payload->copy_range);
> > + ret = bio_add_page(bio, virt_to_page(payload), total_size,
>
> How is payload allocated ? If it is a structure on-stack in the caller, I am not
> sure it would be wise to do an IO using the thread stack page...
>
> > + offset_in_page(payload));
> > + if (ret != total_size) {
> > + ret = -ENOMEM;
> > + bio_put(bio);
> > + goto err;
> > + }
> > +
> > + ret = submit_bio_wait(bio);
> > +err:
> > + bio_put(bio);
> > + return ret;
> > +
> > +}
> > +
> > +int blk_read_to_buf(struct block_device *bdev, struct blk_copy_payload *payload,
> > + gfp_t gfp_mask, void **buf_p)
> > +{
> > + struct request_queue *q = bdev_get_queue(bdev);
> > + struct bio *bio, *parent = NULL;
> > + void *buf = NULL;
> > + bool is_vmalloc;
> > + int i, nr_srcs, copy_len, ret, cur_size, t_len = 0;
> > +
> > + nr_srcs = payload->copy_range;
> > + copy_len = payload->copy_size << SECTOR_SHIFT;
> > +
> > + buf = kvmalloc(copy_len, gfp_mask);
> > + if (!buf)
> > + return -ENOMEM;
> > + is_vmalloc = is_vmalloc_addr(buf);
> > +
> > + for (i = 0; i < nr_srcs; i++) {
> > + cur_size = payload->range[i].len << SECTOR_SHIFT;
> > +
> > + bio = bio_map_kern(q, buf + t_len, cur_size, gfp_mask);
> > + if (IS_ERR(bio)) {
> > + ret = PTR_ERR(bio);
> > + goto out;
> > + }
> > +
> > + bio->bi_iter.bi_sector = payload->range[i].src;
> > + bio->bi_opf = REQ_OP_READ;
> > + bio_set_dev(bio, bdev);
> > + bio->bi_end_io = NULL;
> > + bio->bi_private = NULL;
> > +
> > + if (parent) {
> > + bio_chain(parent, bio);
> > + submit_bio(parent);
> > + }
> > +
> > + parent = bio;
> > + t_len += cur_size;
> > + }
> > +
> > + ret = submit_bio_wait(bio);
> > + bio_put(bio);
> > + if (is_vmalloc)
> > + invalidate_kernel_vmap_range(buf, copy_len);
> > + if (ret)
> > + goto out;
> > +
> > + *buf_p = buf;
> > + return 0;
> > +out:
> > + kvfree(buf);
> > + return ret;
> > +}
> > +
> > +int blk_write_from_buf(struct block_device *bdev, void *buf, sector_t dest,
> > + int copy_len, gfp_t gfp_mask)
> > +{
> > + struct request_queue *q = bdev_get_queue(bdev);
> > + struct bio *bio;
> > + int ret;
> > +
> > + bio = bio_map_kern(q, buf, copy_len, gfp_mask);
> > + if (IS_ERR(bio)) {
> > + ret = PTR_ERR(bio);
> > + goto out;
> > + }
> > + bio_set_dev(bio, bdev);
> > + bio->bi_opf = REQ_OP_WRITE;
> > + bio->bi_iter.bi_sector = dest;
> > +
> > + bio->bi_end_io = NULL;
> > + ret = submit_bio_wait(bio);
> > + bio_put(bio);
> > +out:
> > + return ret;
> > +}
> > +
> > +int blk_prepare_payload(struct block_device *bdev, int nr_srcs, struct range_entry *rlist,
> > + gfp_t gfp_mask, struct blk_copy_payload **payload_p)
> > +{
> > +
> > + struct request_queue *q = bdev_get_queue(bdev);
> > + struct blk_copy_payload *payload;
> > + sector_t bs_mask;
> > + sector_t src_sects, len = 0, total_len = 0;
> > + int i, ret, total_size;
> > +
> > + if (!q)
> > + return -ENXIO;
> > +
> > + if (!nr_srcs)
> > + return -EINVAL;
> > +
> > + if (bdev_read_only(bdev))
> > + return -EPERM;
> > +
> > + bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
> > +
> > + total_size = struct_size(payload, range, nr_srcs);
> > + payload = kmalloc(total_size, gfp_mask);
> > + if (!payload)
> > + return -ENOMEM;
>
> OK. So this is what goes into the bio. The function blk_copy_offload() assumes
> this is at most one page, so total_size <= PAGE_SIZE. Where is that checked ?
>
CMIIW. As payload was allocated via kmalloc, it would be represented by a single
contiguous segment. In case it crosses one page, rely on multi-page bio_vec to
cover it.
> > +
> > + for (i = 0; i < nr_srcs; i++) {
> > + /* copy payload provided are in bytes */
> > + src_sects = rlist[i].src;
> > + if (src_sects & bs_mask) {
> > + ret = -EINVAL;
> > + goto err;
> > + }
> > + src_sects = src_sects >> SECTOR_SHIFT;
> > +
> > + if (len & bs_mask) {
> > + ret = -EINVAL;
> > + goto err;
> > + }
> > +
> > + len = rlist[i].len >> SECTOR_SHIFT;
> > +
> > + total_len += len;
> > +
> > + WARN_ON_ONCE((src_sects << 9) > UINT_MAX);
> > +
> > + payload->range[i].src = src_sects;
> > + payload->range[i].len = len;
> > + }
> > +
> > + /* storing # of source ranges */
> > + payload->copy_range = i;
> > + /* storing copy len so far */
> > + payload->copy_size = total_len;
>
> The comments here make the code ugly. Rename the variables and structure fields
> to have something self explanatory.
>
Agreed.
> > +
> > + *payload_p = payload;
> > + return 0;
> > +err:
> > + kfree(payload);
> > + return ret;
> > +}
> > +
> > +/**
> > + * blkdev_issue_copy - queue a copy
> > + * @bdev: source block device
> > + * @nr_srcs: number of source ranges to copy
> > + * @rlist: array of source ranges (in bytes)
> > + * @dest_bdev: destination block device
> > + * @dest: destination (in bytes)
> > + * @gfp_mask: memory allocation flags (for bio_alloc)
> > + *
> > + * Description:
> > + * Copy array of source ranges from source block device to
> > + * destination block devcie.
> > + */
> > +
> > +
> > +int blkdev_issue_copy(struct block_device *bdev, int nr_srcs,
> > + struct range_entry *src_rlist, struct block_device *dest_bdev,
> > + sector_t dest, gfp_t gfp_mask)
> > +{
> > + struct request_queue *q = bdev_get_queue(bdev);
> > + struct blk_copy_payload *payload;
> > + sector_t bs_mask, dest_sect;
> > + void *buf = NULL;
> > + int ret;
> > +
> > + ret = blk_prepare_payload(bdev, nr_srcs, src_rlist, gfp_mask, &payload);
> > + if (ret)
> > + return ret;
> > +
> > + bs_mask = (bdev_logical_block_size(dest_bdev) >> 9) - 1;
> > + if (dest & bs_mask) {
> > + return -EINVAL;
> > + goto out;
> > + }
> > + dest_sect = dest >> SECTOR_SHIFT;
>
> dest should already be a 512B sector as all block layer functions interface use
> this unit. What is this doing ?
>
As source ranges and length received were in bytes, to keep things
same, dest was
also chosen to be in bytes. Seems wrong. Will change it to the 512B sector.
>
> > +
> > + if (bdev == dest_bdev && q->limits.copy_offload) {
> > + ret = blk_copy_offload(bdev, payload, dest_sect, gfp_mask);
> > + if (ret)
> > + goto out;
> > + } else {
> > + ret = blk_read_to_buf(bdev, payload, gfp_mask, &buf);
> > + if (ret)
> > + goto out;
> > + ret = blk_write_from_buf(dest_bdev, buf, dest_sect,
> > + payload->copy_size << SECTOR_SHIFT, gfp_mask);
>
> Arg... This is really not pretty. At the very least, this should all be in a
> blk_copy_emulate() helper or something named like that.
>
Okay. Will move this to a helper.
> My worry though is that this likely slow for large copies, not to mention that
> buf is likely to fail to allocate for large copy cases. As commented previously,
> dm-kcopyd already does such copy well, with a read-write streaming pipeline and
> zone support too for the write side. This should really be reused, at least
> partly, instead of re-implementing this read-write here.
>
I was a bit hesitant to use dm layer code in the block layer. It makes sense to
reuse the code as much as possible. Will try to reuse dm-kcopyd code for copy
emulation part.
>
> > + }
> > +
> > + if (buf)
> > + kvfree(buf);
> > +out:
> > + kvfree(payload);
> > + return ret;
> > +}
> > +EXPORT_SYMBOL(blkdev_issue_copy);
> > +
> > /**
> > * __blkdev_issue_write_same - generate number of bios with same page
> > * @bdev: target blockdev
> > diff --git a/block/blk-merge.c b/block/blk-merge.c
> > index 808768f6b174..4e04f24e13c1 100644
> > --- a/block/blk-merge.c
> > +++ b/block/blk-merge.c
> > @@ -309,6 +309,8 @@ void __blk_queue_split(struct bio **bio, unsigned int *nr_segs)
> > struct bio *split = NULL;
> >
> > switch (bio_op(*bio)) {
> > + case REQ_OP_COPY:
> > + break;
> > case REQ_OP_DISCARD:
> > case REQ_OP_SECURE_ERASE:
> > split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs);
> > diff --git a/block/blk-settings.c b/block/blk-settings.c
> > index 43990b1d148b..93c15ba45a69 100644
> > --- a/block/blk-settings.c
> > +++ b/block/blk-settings.c
> > @@ -60,6 +60,10 @@ void blk_set_default_limits(struct queue_limits *lim)
> > lim->io_opt = 0;
> > lim->misaligned = 0;
> > lim->zoned = BLK_ZONED_NONE;
> > + lim->copy_offload = 0;
> > + lim->max_copy_sectors = 0;
> > + lim->max_copy_nr_ranges = 0;
> > + lim->max_copy_range_sectors = 0;
> > }
> > EXPORT_SYMBOL(blk_set_default_limits);
> >
> > @@ -565,6 +569,12 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
> > if (b->chunk_sectors)
> > t->chunk_sectors = gcd(t->chunk_sectors, b->chunk_sectors);
> >
> > + /* simple copy not supported in stacked devices */
> > + t->copy_offload = 0;
> > + t->max_copy_sectors = 0;
> > + t->max_copy_range_sectors = 0;
> > + t->max_copy_nr_ranges = 0;
> > +
> > /* Physical block size a multiple of the logical block size? */
> > if (t->physical_block_size & (t->logical_block_size - 1)) {
> > t->physical_block_size = t->logical_block_size;
> > diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> > index b513f1683af0..51b35a8311d9 100644
> > --- a/block/blk-sysfs.c
> > +++ b/block/blk-sysfs.c
> > @@ -166,6 +166,47 @@ static ssize_t queue_discard_granularity_show(struct request_queue *q, char *pag
> > return queue_var_show(q->limits.discard_granularity, page);
> > }
> >
> > +static ssize_t queue_copy_offload_show(struct request_queue *q, char *page)
> > +{
> > + return queue_var_show(q->limits.copy_offload, page);
> > +}
> > +
> > +static ssize_t queue_copy_offload_store(struct request_queue *q,
> > + const char *page, size_t count)
> > +{
> > + unsigned long copy_offload;
> > + ssize_t ret = queue_var_store(©_offload, page, count);
> > +
> > + if (ret < 0)
> > + return ret;
> > +
> > + if (copy_offload < 0 || copy_offload > 1)
>
> err... "copy_offload != 1" ?
Initial thought was to keep it either 0 or 1. I'll change it to 0 or else.
>
> > + return -EINVAL;
> > +
> > + if (q->limits.max_copy_sectors == 0 && copy_offload == 1)
> > + return -EINVAL;
> > +
> > + q->limits.copy_offload = copy_offload;
> > + return ret;
> > +}
> > +
> > +static ssize_t queue_max_copy_sectors_show(struct request_queue *q, char *page)
> > +{
> > + return queue_var_show(q->limits.max_copy_sectors, page);
> > +}
> > +
> > +static ssize_t queue_max_copy_range_sectors_show(struct request_queue *q,
> > + char *page)
> > +{
> > + return queue_var_show(q->limits.max_copy_range_sectors, page);
> > +}
> > +
> > +static ssize_t queue_max_copy_nr_ranges_show(struct request_queue *q,
> > + char *page)
> > +{
> > + return queue_var_show(q->limits.max_copy_nr_ranges, page);
> > +}
> > +
> > static ssize_t queue_discard_max_hw_show(struct request_queue *q, char *page)
> > {
> >
> > @@ -591,6 +632,11 @@ QUEUE_RO_ENTRY(queue_nr_zones, "nr_zones");
> > QUEUE_RO_ENTRY(queue_max_open_zones, "max_open_zones");
> > QUEUE_RO_ENTRY(queue_max_active_zones, "max_active_zones");
> >
> > +QUEUE_RW_ENTRY(queue_copy_offload, "copy_offload");
> > +QUEUE_RO_ENTRY(queue_max_copy_sectors, "max_copy_sectors");
> > +QUEUE_RO_ENTRY(queue_max_copy_range_sectors, "max_copy_range_sectors");
> > +QUEUE_RO_ENTRY(queue_max_copy_nr_ranges, "max_copy_nr_ranges");
> > +
> > QUEUE_RW_ENTRY(queue_nomerges, "nomerges");
> > QUEUE_RW_ENTRY(queue_rq_affinity, "rq_affinity");
> > QUEUE_RW_ENTRY(queue_poll, "io_poll");
> > @@ -636,6 +682,10 @@ static struct attribute *queue_attrs[] = {
> > &queue_discard_max_entry.attr,
> > &queue_discard_max_hw_entry.attr,
> > &queue_discard_zeroes_data_entry.attr,
> > + &queue_copy_offload_entry.attr,
> > + &queue_max_copy_sectors_entry.attr,
> > + &queue_max_copy_range_sectors_entry.attr,
> > + &queue_max_copy_nr_ranges_entry.attr,
> > &queue_write_same_max_entry.attr,
> > &queue_write_zeroes_max_entry.attr,
> > &queue_zone_append_max_entry.attr,
> > diff --git a/block/blk-zoned.c b/block/blk-zoned.c
> > index 7a68b6e4300c..02069178d51e 100644
> > --- a/block/blk-zoned.c
> > +++ b/block/blk-zoned.c
> > @@ -75,6 +75,7 @@ bool blk_req_needs_zone_write_lock(struct request *rq)
> > case REQ_OP_WRITE_ZEROES:
> > case REQ_OP_WRITE_SAME:
> > case REQ_OP_WRITE:
> > + case REQ_OP_COPY:
> > return blk_rq_zone_is_seq(rq);
> > default:
> > return false;
> > diff --git a/block/bounce.c b/block/bounce.c
> > index d3f51acd6e3b..5e052afe8691 100644
> > --- a/block/bounce.c
> > +++ b/block/bounce.c
> > @@ -254,6 +254,7 @@ static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,
> > bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;
> >
> > switch (bio_op(bio)) {
> > + case REQ_OP_COPY:
> > case REQ_OP_DISCARD:
> > case REQ_OP_SECURE_ERASE:
> > case REQ_OP_WRITE_ZEROES:
> > diff --git a/block/ioctl.c b/block/ioctl.c
> > index d61d652078f4..d50b6abe2883 100644
> > --- a/block/ioctl.c
> > +++ b/block/ioctl.c
> > @@ -133,6 +133,47 @@ static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode,
> > GFP_KERNEL, flags);
> > }
> >
> > +static int blk_ioctl_copy(struct block_device *bdev, fmode_t mode,
> > + unsigned long arg)
> > +{
> > + struct copy_range crange;
> > + struct range_entry *rlist;
> > + struct request_queue *q = bdev_get_queue(bdev);
> > + sector_t dest;
> > + int ret;
> > +
> > + if (!(mode & FMODE_WRITE))
> > + return -EBADF;
> > +
> > + if (!blk_queue_copy(q))
> > + return -EOPNOTSUPP;
>
> But you added the read-write emulation. So what is the point here ? This ioctl
> should work for any device, with or without simple copy support. Did you test that ?
>
Sorry. It was a mistake. Will fix this.
> > +
> > + if (copy_from_user(&crange, (void __user *)arg, sizeof(crange)))
> > + return -EFAULT;
> > +
> > + if (crange.dest & ((1 << SECTOR_SHIFT) - 1))
> > + return -EFAULT;
> > + dest = crange.dest;
> > +
> > + rlist = kmalloc_array(crange.nr_range, sizeof(*rlist),
> > + GFP_KERNEL);
> > +
>
> Unnecessary blank line here.
>
> > + if (!rlist)
> > + return -ENOMEM;
> > +
> > + if (copy_from_user(rlist, (void __user *)crange.range_list,
> > + sizeof(*rlist) * crange.nr_range)) {
> > + ret = -EFAULT;
> > + goto out;
> > + }
> > +
> > + ret = blkdev_issue_copy(bdev, crange.nr_range, rlist, bdev, dest,
> > + GFP_KERNEL);
> > +out:
> > + kfree(rlist);
> > + return ret;
> > +}
> > +
> > static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode,
> > unsigned long arg)
> > {
> > @@ -458,6 +499,8 @@ static int blkdev_common_ioctl(struct block_device *bdev, fmode_t mode,
> > case BLKSECDISCARD:
> > return blk_ioctl_discard(bdev, mode, arg,
> > BLKDEV_DISCARD_SECURE);
> > + case BLKCOPY:
> > + return blk_ioctl_copy(bdev, mode, arg);
> > case BLKZEROOUT:
> > return blk_ioctl_zeroout(bdev, mode, arg);
> > case BLKREPORTZONE:
> > diff --git a/include/linux/bio.h b/include/linux/bio.h
> > index 1edda614f7ce..164313bdfb35 100644
> > --- a/include/linux/bio.h
> > +++ b/include/linux/bio.h
> > @@ -71,6 +71,7 @@ static inline bool bio_has_data(struct bio *bio)
> > static inline bool bio_no_advance_iter(const struct bio *bio)
> > {
> > return bio_op(bio) == REQ_OP_DISCARD ||
> > + bio_op(bio) == REQ_OP_COPY ||
> > bio_op(bio) == REQ_OP_SECURE_ERASE ||
> > bio_op(bio) == REQ_OP_WRITE_SAME ||
> > bio_op(bio) == REQ_OP_WRITE_ZEROES;
> > diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> > index 866f74261b3b..d4d11e9ff814 100644
> > --- a/include/linux/blk_types.h
> > +++ b/include/linux/blk_types.h
> > @@ -380,6 +380,8 @@ enum req_opf {
> > REQ_OP_ZONE_RESET = 15,
> > /* reset all the zone present on the device */
> > REQ_OP_ZONE_RESET_ALL = 17,
> > + /* copy ranges within device */
> > + REQ_OP_COPY = 19,
> >
> > /* SCSI passthrough using struct scsi_request */
> > REQ_OP_SCSI_IN = 32,
> > @@ -506,6 +508,11 @@ static inline bool op_is_discard(unsigned int op)
> > return (op & REQ_OP_MASK) == REQ_OP_DISCARD;
> > }
> >
> > +static inline bool op_is_copy(unsigned int op)
> > +{
> > + return (op & REQ_OP_MASK) == REQ_OP_COPY;
> > +}
> > +
> > /*
> > * Check if a bio or request operation is a zone management operation, with
> > * the exception of REQ_OP_ZONE_RESET_ALL which is treated as a special case
> > @@ -565,4 +572,12 @@ struct blk_rq_stat {
> > u64 batch;
> > };
> >
> > +struct blk_copy_payload {
> > + sector_t dest;
> > + int copy_range;
> > + int copy_size;
> > + int err;
> > + struct range_entry range[];
> > +};
> > +
> > #endif /* __LINUX_BLK_TYPES_H */
> > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> > index 81f9e7bec16c..4c7e861e57e4 100644
> > --- a/include/linux/blkdev.h
> > +++ b/include/linux/blkdev.h
> > @@ -340,10 +340,14 @@ struct queue_limits {
> > unsigned int max_zone_append_sectors;
> > unsigned int discard_granularity;
> > unsigned int discard_alignment;
> > + unsigned int copy_offload;
> > + unsigned int max_copy_sectors;
> >
> > unsigned short max_segments;
> > unsigned short max_integrity_segments;
> > unsigned short max_discard_segments;
> > + unsigned short max_copy_range_sectors;
> > + unsigned short max_copy_nr_ranges;
> >
> > unsigned char misaligned;
> > unsigned char discard_misaligned;
> > @@ -625,6 +629,7 @@ struct request_queue {
> > #define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */
> > #define QUEUE_FLAG_HCTX_ACTIVE 28 /* at least one blk-mq hctx is active */
> > #define QUEUE_FLAG_NOWAIT 29 /* device supports NOWAIT */
> > +#define QUEUE_FLAG_COPY 30 /* supports copy */
>
> I think this should be called QUEUE_FLAG_SIMPLE_COPY to indicate more precisely
> the type of copy supported. SCSI XCOPY is more advanced...
>
Agreed.
> >
> > #define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
> > (1 << QUEUE_FLAG_SAME_COMP) | \
> > @@ -647,6 +652,7 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);
> > #define blk_queue_io_stat(q) test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags)
> > #define blk_queue_add_random(q) test_bit(QUEUE_FLAG_ADD_RANDOM, &(q)->queue_flags)
> > #define blk_queue_discard(q) test_bit(QUEUE_FLAG_DISCARD, &(q)->queue_flags)
> > +#define blk_queue_copy(q) test_bit(QUEUE_FLAG_COPY, &(q)->queue_flags)
> > #define blk_queue_zone_resetall(q) \
> > test_bit(QUEUE_FLAG_ZONE_RESETALL, &(q)->queue_flags)
> > #define blk_queue_secure_erase(q) \
> > @@ -1061,6 +1067,9 @@ static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
> > return min(q->limits.max_discard_sectors,
> > UINT_MAX >> SECTOR_SHIFT);
> >
> > + if (unlikely(op == REQ_OP_COPY))
> > + return q->limits.max_copy_sectors;
> > +
> > if (unlikely(op == REQ_OP_WRITE_SAME))
> > return q->limits.max_write_same_sectors;
> >
> > @@ -1335,6 +1344,10 @@ extern int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
> > sector_t nr_sects, gfp_t gfp_mask, int flags,
> > struct bio **biop);
> >
> > +extern int blkdev_issue_copy(struct block_device *bdev, int nr_srcs,
> > + struct range_entry *src_rlist, struct block_device *dest_bdev,
> > + sector_t dest, 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 */
> >
> > diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> > index f44eb0a04afd..5cadb176317a 100644
> > --- a/include/uapi/linux/fs.h
> > +++ b/include/uapi/linux/fs.h
> > @@ -64,6 +64,18 @@ struct fstrim_range {
> > __u64 minlen;
> > };
> >
> > +struct range_entry {
> > + __u64 src;
> > + __u64 len;
> > +};
> > +
> > +struct copy_range {
> > + __u64 dest;
> > + __u64 nr_range;
> > + __u64 range_list;
> > + __u64 rsvd;
> > +};
> > +
> > /* extent-same (dedupe) ioctls; these MUST match the btrfs ioctl definitions */
> > #define FILE_DEDUPE_RANGE_SAME 0
> > #define FILE_DEDUPE_RANGE_DIFFERS 1
> > @@ -184,6 +196,7 @@ struct fsxattr {
> > #define BLKSECDISCARD _IO(0x12,125)
> > #define BLKROTATIONAL _IO(0x12,126)
> > #define BLKZEROOUT _IO(0x12,127)
> > +#define BLKCOPY _IOWR(0x12, 128, struct copy_range)
> > /*
> > * A jump here: 130-131 are reserved for zoned block devices
> > * (see uapi/linux/blkzoned.h)
> >
>
>
> --
> Damien Le Moal
> Western Digital Research
Thanks,
Selva