Commit 25532d08 authored by Shuhei Matsumoto's avatar Shuhei Matsumoto Committed by Changpeng Liu
Browse files

bdev/split: call get buffer function before forwarding read I/O to the base bdev 



iSCSI target does not allocate data buffer on read, and delegate
allocation to the bdev.

When the bdev is a split vbdev, the split vbdev does not allocate
data buffer and delegate allocation to the backend bdev.

In this case, iSCSI target expects the buffer is allocated until
notifying completion to the split vbdev. However, the split vbdev
notifies completion to the backend bdev when calling the callback
of iSCSI target. The backend bdev frees the buffer immediately,
but iSCSI target still uses the buffer. If the buffer is reused
by another I/O, data corruption will occur.

For this issue, vbdev_split_submti_request() calls
spdk_bdev_io_get_buf() when the I/O is read, and its callback
vbdev_split_get_buf_cb calls _vbdev_split_submit_request() then.

This will ensure the buffer is allocated before forwarding I/O
to the backed bdev.

Signed-off-by: default avatarShuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Change-Id: Icfd0663b548479ac0bf6b5b49420f144142e3300
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/461348


Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: default avatarBen Walker <benjamin.walker@intel.com>
Reviewed-by: default avatarChangpeng Liu <changpeng.liu@intel.com>
parent 5f5a5d4a

lib/bdev/split/vbdev_split.c

+28 −3
Original line number Diff line number Diff line
@@ -83,7 +83,7 @@ static int vbdev_split_config_json(struct spdk_json_write_ctx *w); 
static int vbdev_split_get_ctx_size(void);



static void

vbdev_split_submit_request(struct spdk_io_channel *_ch, struct spdk_bdev_io *bdev_io);

_vbdev_split_submit_request(struct spdk_io_channel *_ch, struct spdk_bdev_io *bdev_io);



static struct spdk_bdev_module split_if = {

	.name = "split",
@@ -126,7 +126,7 @@ vbdev_split_resubmit_io(void *arg) 
{

	struct vbdev_split_bdev_io *split_io = (struct vbdev_split_bdev_io *)arg;



	vbdev_split_submit_request(split_io->ch, split_io->bdev_io);

	_vbdev_split_submit_request(split_io->ch, split_io->bdev_io);

}



static void
@@ -147,7 +147,7 @@ vbdev_split_queue_io(struct vbdev_split_bdev_io *split_io) 
}



static void

vbdev_split_submit_request(struct spdk_io_channel *_ch, struct spdk_bdev_io *bdev_io)

_vbdev_split_submit_request(struct spdk_io_channel *_ch, struct spdk_bdev_io *bdev_io)

{

	struct vbdev_split_channel *ch = spdk_io_channel_get_ctx(_ch);

	struct vbdev_split_bdev_io *io_ctx = (struct vbdev_split_bdev_io *)bdev_io->driver_ctx;
@@ -167,6 +167,31 @@ vbdev_split_submit_request(struct spdk_io_channel *_ch, struct spdk_bdev_io *bde 
	}

}



static void

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

{

	if (!success) {

		spdk_bdev_io_complete(bdev_io, SPDK_BDEV_IO_STATUS_FAILED);

		return;

	}



	_vbdev_split_submit_request(ch, bdev_io);

}



static void

vbdev_split_submit_request(struct spdk_io_channel *_ch, struct spdk_bdev_io *bdev_io)

{

	switch (bdev_io->type) {

	case SPDK_BDEV_IO_TYPE_READ:

		spdk_bdev_io_get_buf(bdev_io, vbdev_split_get_buf_cb,

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

		break;

	default:

		_vbdev_split_submit_request(_ch, bdev_io);

		break;

	}

}



static int

vbdev_split_dump_info_json(void *ctx, struct spdk_json_write_ctx *w)

{