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bdev: Emulate zero copy support when necessary

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

Change-Id: Iabd7ff474bf740b096f38bd47196987cbd89e915
Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/416465
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
This commit is contained in:
Ben Walker 2019-04-02 11:25:10 -07:00 committed by Jim Harris
parent 7e4911c922
commit 946ef1dc47
1 changed files with 62 additions and 1 deletions
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63
lib/bdev/bdev.c
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@ -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);
spdk_bdev_io_submit(bdev_io);
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;
}
@ -2807,7 +2854,21 @@ 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;
}