On 07.12.2020 15:11, Christoph Hellwig wrote:
So, I'm really worried about: a) a good use case. GC in f2fs or btrfs seem like good use cases, as does accelating dm-kcopyd. I agree with Damien that lifting dm-kcopyd to common code would also be really nice. I'm not 100% sure it should be a requirement, but it sure would be nice to have I don't think just adding an ioctl is enough of a use case for complex kernel infrastructure.
We are looking at dm-kcopyd. I would have liked to start with a very specific use case and build from there, but I see Damien's and Keith's point of having a default path. I believe we can add this to the next version.
b) We had a bunch of different attempts at SCSI XCOPY support form IIRC Martin, Bart and Mikulas. I think we need to pull them into this discussion, and make sure whatever we do covers the SCSI needs.
Agree. We discussed a lot about the scope and agreed that everything outside of the specifics of Simple Copy requires the input from the ones that have worked on XCOPY support in the past.
On Fri, Dec 04, 2020 at 03:16:57PM +0530, SelvaKumar S wrote:This patchset tries to add support for TP4065a ("Simple Copy Command"), v2020.05.04 ("Ratified") The Specification can be found in following link. https://nvmexpress.org/wp-content/uploads/NVM-Express-1.4-Ratified-TPs-1.zip This is an RFC. Looking forward for any feedbacks or other alternate designs for plumbing simple copy to IO stack. Simple copy command is a copy offloading operation and is used to copy multiple contiguous ranges (source_ranges) of LBA's to a single destination LBA within the device reducing traffic between host and device. This implementation accepts destination, no of sources and arrays of source ranges from application and attach it as payload to the bio and submits to the device. Following limits are added to queue limits and are exposed in sysfs to userspace - *max_copy_sectors* limits the sum of all source_range length - *max_copy_nr_ranges* limits the number of source ranges - *max_copy_range_sectors* limit the maximum number of sectors that can constitute a single source range. Changes from v1: 1. Fix memory leak in __blkdev_issue_copy 2. Unmark blk_check_copy inline 3. Fix line break in blk_check_copy_eod 4. Remove p checks and made code more readable 5. Don't use bio_set_op_attrs and remove op and set bi_opf directly 6. Use struct_size to calculate total_size 7. Fix partition remap of copy destination 8. Remove mcl,mssrl,msrc from nvme_ns 9. Initialize copy queue limits to 0 in nvme_config_copy 10. Remove return in QUEUE_FLAG_COPY check 11. Remove unused OCFS SelvaKumar S (2): block: add simple copy support nvme: add simple copy support block/blk-core.c | 94 ++++++++++++++++++++++++++--- block/blk-lib.c | 123 ++++++++++++++++++++++++++++++++++++++ block/blk-merge.c | 2 + block/blk-settings.c | 11 ++++ block/blk-sysfs.c | 23 +++++++ block/blk-zoned.c | 1 + block/bounce.c | 1 + block/ioctl.c | 43 +++++++++++++ drivers/nvme/host/core.c | 87 +++++++++++++++++++++++++++ include/linux/bio.h | 1 + include/linux/blk_types.h | 15 +++++ include/linux/blkdev.h | 15 +++++ include/linux/nvme.h | 43 ++++++++++++- include/uapi/linux/fs.h | 13 ++++ 14 files changed, 461 insertions(+), 11 deletions(-) -- 2.25.1---end quoted text---
