SelvaKumar S: This didn't show up on dm-devel, sorry for the OT reply...
On Mon, Jan 04, 2021 at 12:47:11PM +0000, Damien Le Moal 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 +++
This series should also be cc'd to linux-api since you're adding a new
userspace api.
Alternately, save yourself the trouble of passing userspace API review
by hooking this up to the existing copy_file_range call in the vfs. /me
hopes you sent blktests to check the operation of this thing, since none
of the original patches made it to this list.
If you really /do/ need a new kernel call for this, then please send in
a manpage documenting the fields of struct range_entry and copy_range,
and how users are supposed to use this.
<now jumping to the ioctl definition because Damien already reviewed the
plumbing...>
> > 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;
Is this an offset? Or the fd of an open bdev?
> > + __u64 len;
> > +};
> > +
> > +struct copy_range {
> > + __u64 dest;
> > + __u64 nr_range;
> > + __u64 range_list;
Hm, I think this is a pointer? Why not just put the range_entry array
at the end of struct copy_range?
> > + __u64 rsvd;
Also needs a flags argument so we don't have to add BLKCOPY2 in like 3
months.
--D
> > +};
> > +
> > /* 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
>
>
>
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