Commit 946ef1dc authored by Ben Walker's avatar Ben Walker Committed by Jim Harris
Browse files

bdev: Emulate zero copy support when necessary 



For bdevs that don't support zero copy, emulate the
API using regular read and write operations.

Change-Id: Iabd7ff474bf740b096f38bd47196987cbd89e915
Signed-off-by: default avatarBen Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/416465


Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: default avatarShuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: default avatarJim Harris <james.r.harris@intel.com>
parent 7e4911c9

lib/bdev/bdev.c

+62 −1
Original line number Diff line number Diff line
@@ -1799,6 +1799,11 @@ spdk_bdev_io_type_supported(struct spdk_bdev *bdev, enum spdk_bdev_io_type io_ty 
			/* The bdev layer will emulate write zeroes as long as write is supported. */

			supported = _spdk_bdev_io_type_supported(bdev, SPDK_BDEV_IO_TYPE_WRITE);

			break;

		case SPDK_BDEV_IO_TYPE_ZCOPY:

			/* Zero copy can be emulated with regular read and write */

			supported = _spdk_bdev_io_type_supported(bdev, SPDK_BDEV_IO_TYPE_READ) &&

				    _spdk_bdev_io_type_supported(bdev, SPDK_BDEV_IO_TYPE_WRITE);

			break;

		default:

			break;

		}
@@ -2752,6 +2757,29 @@ spdk_bdev_writev_blocks(struct spdk_bdev_desc *desc, struct spdk_io_channel *ch, 
	return 0;

}



static void

bdev_zcopy_get_buf(struct spdk_io_channel *ch, struct spdk_bdev_io *bdev_io, bool success)

{

	if (!success) {

		/* Don't use spdk_bdev_io_complete here - this bdev_io was never actually submitted. */

		bdev_io->internal.status = SPDK_BDEV_IO_STATUS_NOMEM;

		bdev_io->internal.cb(bdev_io, success, bdev_io->internal.caller_ctx);

		return;

	}



	if (bdev_io->u.bdev.zcopy.populate) {

		/* Read the real data into the buffer */

		bdev_io->type = SPDK_BDEV_IO_TYPE_READ;

		bdev_io->internal.status = SPDK_BDEV_IO_STATUS_PENDING;

		spdk_bdev_io_submit(bdev_io);

		return;

	}



	/* Don't use spdk_bdev_io_complete here - this bdev_io was never actually submitted. */

	bdev_io->internal.status = SPDK_BDEV_IO_STATUS_SUCCESS;

	bdev_io->internal.cb(bdev_io, success, bdev_io->internal.caller_ctx);

}



int

spdk_bdev_zcopy_start(struct spdk_bdev_desc *desc, struct spdk_io_channel *ch,

		      uint64_t offset_blocks, uint64_t num_blocks,
@@ -2784,12 +2812,21 @@ spdk_bdev_zcopy_start(struct spdk_bdev_desc *desc, struct spdk_io_channel *ch, 
	bdev_io->type = SPDK_BDEV_IO_TYPE_ZCOPY;

	bdev_io->u.bdev.num_blocks = num_blocks;

	bdev_io->u.bdev.offset_blocks = offset_blocks;

	bdev_io->u.bdev.iovs = NULL;

	bdev_io->u.bdev.iovcnt = 0;

	bdev_io->u.bdev.zcopy.populate = populate ? 1 : 0;

	bdev_io->u.bdev.zcopy.commit = 0;

	bdev_io->u.bdev.zcopy.start = 1;

	spdk_bdev_io_init(bdev_io, bdev, cb_arg, cb);



	if (_spdk_bdev_io_type_supported(bdev, SPDK_BDEV_IO_TYPE_ZCOPY)) {

		spdk_bdev_io_submit(bdev_io);

	} else {

		/* Emulate zcopy by allocating a buffer */

		spdk_bdev_io_get_buf(bdev_io, bdev_zcopy_get_buf,

				     bdev_io->u.bdev.num_blocks * bdev->blocklen);

	}



	return 0;

}
@@ -2797,6 +2834,16 @@ int 
spdk_bdev_zcopy_end(struct spdk_bdev_io *bdev_io, bool commit,

		    spdk_bdev_io_completion_cb cb, void *cb_arg)

{

	struct spdk_bdev *bdev = bdev_io->bdev;



	if (bdev_io->type == SPDK_BDEV_IO_TYPE_READ) {

		/* This can happen if the zcopy was emulated in start */

		if (bdev_io->u.bdev.zcopy.start != 1) {

			return -EINVAL;

		}

		bdev_io->type = SPDK_BDEV_IO_TYPE_ZCOPY;

	}



	if (bdev_io->type != SPDK_BDEV_IO_TYPE_ZCOPY) {

		return -EINVAL;

	}
@@ -2807,10 +2854,24 @@ spdk_bdev_zcopy_end(struct spdk_bdev_io *bdev_io, bool commit, 
	bdev_io->internal.cb = cb;

	bdev_io->internal.status = SPDK_BDEV_IO_STATUS_PENDING;



	if (_spdk_bdev_io_type_supported(bdev, SPDK_BDEV_IO_TYPE_ZCOPY)) {

		spdk_bdev_io_submit(bdev_io);

		return 0;

	}



	if (!bdev_io->u.bdev.zcopy.commit) {

		/* Don't use spdk_bdev_io_complete here - this bdev_io was never actually submitted. */

		bdev_io->internal.status = SPDK_BDEV_IO_STATUS_SUCCESS;

		bdev_io->internal.cb(bdev_io, true, bdev_io->internal.caller_ctx);

		return 0;

	}



	bdev_io->type = SPDK_BDEV_IO_TYPE_WRITE;

	spdk_bdev_io_submit(bdev_io);



	return 0;

}



int

spdk_bdev_write_zeroes(struct spdk_bdev_desc *desc, struct spdk_io_channel *ch,

		       uint64_t offset, uint64_t len,