On 23/06/28 03:45PM, Damien Le Moal wrote:
On 6/28/23 03:36, Nitesh Shetty wrote:
Introduce blkdev_copy_offload which takes similar arguments as
copy_file_range and performs copy offload between two bdevs.
I am confused... I thought it was discussed to only allow copy offload only
within a single bdev for now... Did I missi something ?
Yes, you are right. copy is supported within single bdev only.
We will update this.
Introduce REQ_OP_COPY_DST, REQ_OP_COPY_SRC operation.
Issue REQ_OP_COPY_DST with destination info along with taking a plug.
This flows till request layer and waits for src bio to get merged.
Issue REQ_OP_COPY_SRC with source info and this bio reaches request
layer and merges with dst request.
For any reason, if request comes to driver with either only one of src/dst
info we fail the copy offload.
Larger copy will be divided, based on max_copy_sectors limit.
Suggested-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
Signed-off-by: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>
---
block/blk-core.c | 5 ++
block/blk-lib.c | 177 ++++++++++++++++++++++++++++++++++++++
block/blk-merge.c | 21 +++++
block/blk.h | 9 ++
block/elevator.h | 1 +
include/linux/bio.h | 4 +-
include/linux/blk_types.h | 21 +++++
include/linux/blkdev.h | 4 +
8 files changed, 241 insertions(+), 1 deletion(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 99d8b9812b18..e6714391c93f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -796,6 +796,11 @@ void submit_bio_noacct(struct bio *bio)
if (!q->limits.max_write_zeroes_sectors)
goto not_supported;
break;
+ case REQ_OP_COPY_SRC:
+ case REQ_OP_COPY_DST:
+ if (!blk_queue_copy(q))
+ goto not_supported;
+ break;
default:
break;
}
diff --git a/block/blk-lib.c b/block/blk-lib.c
index e59c3069e835..10c3eadd5bf6 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -115,6 +115,183 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
}
EXPORT_SYMBOL(blkdev_issue_discard);
+/*
+ * For synchronous copy offload/emulation, wait and process all in-flight BIOs.
+ * This must only be called once all bios have been issued so that the refcount
+ * can only decrease. This just waits for all bios to make it through
+ * blkdev_copy_(offload/emulate)_(read/write)_endio.
+ */
+static ssize_t blkdev_copy_wait_io_completion(struct cio *cio)
+{
+ ssize_t ret;
+
+ if (cio->endio)
+ return 0;
+
+ if (atomic_read(&cio->refcount)) {
+ __set_current_state(TASK_UNINTERRUPTIBLE);
+ blk_io_schedule();
+ }
+
+ ret = cio->comp_len;
+ kfree(cio);
+
+ return ret;
+}
+
+static void blkdev_copy_offload_read_endio(struct bio *bio)
+{
+ struct cio *cio = bio->bi_private;
+ sector_t clen;
+
+ if (bio->bi_status) {
+ clen = (bio->bi_iter.bi_sector << SECTOR_SHIFT) - cio->pos_out;
+ cio->comp_len = min_t(sector_t, clen, cio->comp_len);
+ }
+ bio_put(bio);
+
+ if (!atomic_dec_and_test(&cio->refcount))
+ return;
+ if (cio->endio) {
+ cio->endio(cio->private, cio->comp_len);
+ kfree(cio);
+ } else
+ blk_wake_io_task(cio->waiter);
Curly brackets around else missing.
Acked.
+}
+
+/*
+ * __blkdev_copy_offload - Use device's native copy offload feature.
+ * we perform copy operation by sending 2 bio.
+ * 1. We take a plug and send a REQ_OP_COPY_DST bio along with destination
+ * sector and length. Once this bio reaches request layer, we form a request and
+ * wait for src bio to arrive.
+ * 2. We issue REQ_OP_COPY_SRC bio along with source sector and length. Once
+ * this bio reaches request layer and find a request with previously sent
+ * destination info we merge the source bio and return.
+ * 3. Release the plug and request is sent to driver
+ *
+ * Returns the length of bytes copied or error if encountered
+ */
+static ssize_t __blkdev_copy_offload(
+ struct block_device *bdev_in, loff_t pos_in,
+ struct block_device *bdev_out, loff_t pos_out,
+ size_t len, cio_iodone_t endio, void *private, gfp_t gfp_mask)
+{
+ struct cio *cio;
+ struct bio *read_bio, *write_bio;
+ sector_t rem, copy_len, max_copy_len;
+ struct blk_plug plug;
+
+ cio = kzalloc(sizeof(struct cio), GFP_KERNEL);
+ if (!cio)
+ return -ENOMEM;
+ atomic_set(&cio->refcount, 0);
+ cio->waiter = current;
+ cio->endio = endio;
+ cio->private = private;
+
+ max_copy_len = min(bdev_max_copy_sectors(bdev_in),
+ bdev_max_copy_sectors(bdev_out)) << SECTOR_SHIFT;
According to patch 1, this can end up being 0, so the loop below will be infinite.
Agreed. As you suggested earlier, once we remove copy_offload parameter
and checking copy_max_sector to identify copy offload capabilty should
solve this.
Thank you,
Nitesh Shetty
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