On 23/06/28 03:51PM, Damien Le Moal wrote:

On 6/28/23 03:36, Nitesh Shetty wrote:

quoted

For direct block device opened with O_DIRECT, use copy_file_range to
issue device copy offload, and fallback to generic_copy_file_range incase
device copy offload capability is absent.

...if the device does not support copy offload or the device files are not open
with O_DIRECT.

No ?

Yes your right. We will fallback to generic_copy_file_range in either of
these cases.

quoted

Modify checks to allow bdevs to use copy_file_range.

Suggested-by: Ming Lei <redacted>
Signed-off-by: Anuj Gupta <redacted>
Signed-off-by: Nitesh Shetty <redacted>
---
 block/blk-lib.c        | 26 ++++++++++++++++++++++++++
 block/fops.c           | 20 ++++++++++++++++++++
 fs/read_write.c        |  7 +++++--
 include/linux/blkdev.h |  4 ++++
 4 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 09e0d5d51d03..7d8e09a99254 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c

@@ -473,6 +473,32 @@ ssize_t blkdev_copy_offload(
 }
 EXPORT_SYMBOL_GPL(blkdev_copy_offload);

+/* Copy source offset from source block device to destination block
+ * device. Returns the length of bytes copied.
+ */

Multi-line comment style: start with a "/*" line please.

acked

quoted

+ssize_t blkdev_copy_offload_failfast(

What is the "failfast" in the name for ?

We dont want failed copy offload IOs to fallback to block layer copy emulation.
We wanted a API to return error, if offload fails.

quoted

+		struct block_device *bdev_in, loff_t pos_in,
+		struct block_device *bdev_out, loff_t pos_out,
+		size_t len, gfp_t gfp_mask)
+{
+	struct request_queue *in_q = bdev_get_queue(bdev_in);
+	struct request_queue *out_q = bdev_get_queue(bdev_out);
+	ssize_t ret = 0;

You do not need this initialization.

we need this initialization, because __blkdev_copy_offload return number of
bytes copied or error value.
So we can not return 0, incase of success/partial completion.
blkdev_copy_offload_failfast is expected to return number of bytes copied.

quoted

+
+	if (blkdev_copy_sanity_check(bdev_in, pos_in, bdev_out, pos_out, len))
+		return 0;
+
+	if (blk_queue_copy(in_q) && blk_queue_copy(out_q)) {

Given that I think we do not allow copies between different devices, in_q and
out_q should always be the same, no ?

acked, will update this.

quoted

+		ret = __blkdev_copy_offload(bdev_in, pos_in, bdev_out, pos_out,
+				len, NULL, NULL, gfp_mask);

Same here. Why pass 2 bdevs if we only allow copies within the same device ?

acked, will update function arguments to take single bdev.

quoted

+		if (ret < 0)
+			return 0;
+	}
+
+	return ret;

return 0;

Nack, explained above.

Thank you,
Nitesh Shetty