Messages in this thread | | | Subject | Re: [RFC PATCH v5 0/4] add simple copy support | From | Max Gurtovoy <> | Date | Sat, 10 Apr 2021 03:21:57 +0300 |
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On 2/19/2021 2:45 PM, 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 > > 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 doesn't add native copy offload support for stacked > devices rather copy offload is done through emulation. Possible use > cases are F2FS gc and BTRFS relocation/balance. > > *blkdev_issue_copy* takes source bdev, no of sources, array of source > ranges (in sectors), destination bdev and destination offset(in sectors). > If both source and destination block devices are same and copy_offload = 1, > then copy is done through native copy offloading. Copy emulation is used > in other cases. > > As SCSI XCOPY can take two different block devices and no of source range is > equal to 1, this interface can be extended in future to support SCSI XCOPY.
Any idea why this TP wasn't designed for copy offload between 2 different namespaces in the same controller ?
And a simple copy will be the case where the src_nsid == dst_nsid ?
Also why there are multiple source ranges and only one dst range ? We could add a bit to indicate if this range is src or dst..
> > For devices supporting native simple copy, attach the control information > as payload to the bio and submit to the device. For devices without native > copy support, copy emulation is done by reading each source range into memory > and writing it to the destination. Caller can choose not to try > emulation if copy offload is not supported by setting > BLKDEV_COPY_NOEMULATION flag. > > Following limits are added to queue limits and are exposed in sysfs > to userspace > - *copy_offload* controls copy_offload. set 0 to disable copy > offload, 1 to enable native copy offloading support. > - *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. > > max_copy_sectors = 0 indicates the device doesn't support copy > offloading. > > *copy offload* sysfs entry is configurable and can be used toggle > between emulation and native support depending upon the usecase. > > Changes from v4 > > 1. Extend dm-kcopyd to leverage copy-offload, while copying within the > same device. The other approach was to have copy-emulation by moving > dm-kcopyd to block layer. But it also required moving core dm-io infra, > causing a massive churn across multiple dm-targets. > > 2. Remove export in bio_map_kern() > 3. Change copy_offload sysfs to accept 0 or else > 4. Rename copy support flag to QUEUE_FLAG_SIMPLE_COPY > 5. Rename payload entries, add source bdev field to be used while > partition remapping, remove copy_size > 6. Change the blkdev_issue_copy() interface to accept destination and > source values in sector rather in bytes > 7. Add payload to bio using bio_map_kern() for copy_offload case > 8. Add check to return error if one of the source range length is 0 > 9. Add BLKDEV_COPY_NOEMULATION flag to allow user to not try copy > emulation incase of copy offload is not supported. Caller can his use > his existing copying logic to complete the io. > 10. Bug fix copy checks and reduce size of rcu_lock() > > Planned for next: > - adding blktests > - handling larger (than device limits) copy > - decide on ioctl interface (man-page etc.) > > Changes from v3 > > 1. gfp_flag fixes. > 2. Export bio_map_kern() and use it to allocate and add pages to bio. > 3. Move copy offload, reading to buf, writing from buf to separate functions. > 4. Send read bio of copy offload by chaining them and submit asynchronously. > 5. Add gendisk->part0 and part->bd_start_sect changes to blk_check_copy(). > 6. Move single source range limit check to blk_check_copy() > 7. Rename __blkdev_issue_copy() to blkdev_issue_copy and remove old helper. > 8. Change blkdev_issue_copy() interface generic to accepts destination bdev > to support XCOPY as well. > 9. Add invalidate_kernel_vmap_range() after reading data for vmalloc'ed memory. > 10. Fix buf allocoation logic to allocate buffer for the total size of copy. > 11. Reword patch commit description. > > Changes from v2 > > 1. Add emulation support for devices not supporting copy. > 2. Add *copy_offload* sysfs entry to enable and disable copy_offload > in devices supporting simple copy. > 3. Remove simple copy support for stacked devices. > > 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 (4): > block: make bio_map_kern() non static > block: add simple copy support > nvme: add simple copy support > dm kcopyd: add simple copy offload support > > block/blk-core.c | 102 +++++++++++++++-- > block/blk-lib.c | 223 ++++++++++++++++++++++++++++++++++++++ > block/blk-map.c | 2 +- > block/blk-merge.c | 2 + > block/blk-settings.c | 10 ++ > block/blk-sysfs.c | 47 ++++++++ > block/blk-zoned.c | 1 + > block/bounce.c | 1 + > block/ioctl.c | 33 ++++++ > drivers/md/dm-kcopyd.c | 49 ++++++++- > drivers/nvme/host/core.c | 87 +++++++++++++++ > include/linux/bio.h | 1 + > include/linux/blk_types.h | 14 +++ > include/linux/blkdev.h | 17 +++ > include/linux/nvme.h | 43 +++++++- > include/uapi/linux/fs.h | 13 +++ > 16 files changed, 627 insertions(+), 18 deletions(-) >
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