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vdi: leave bounce buffering to block layer 

vdi.c really works as if it implemented bdrv_read and bdrv_write.  However,
because only vector I/O is supported by the asynchronous callbacks, it
went through extra pain to bounce-buffer the I/O.  This can be handled
by the block layer now that the format is coroutine-based.

Acked-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Paolo Bonzini 2012-03-19 18:07:49 +01:00 committed by Kevin Wolf
parent bfc45fc183
commit a7a43aa199
1 changed files with 12 additions and 55 deletions
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67
block/vdi.c
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@ -143,12 +143,6 @@ void uuid_unparse(const uuid_t uu, char *out)
}
#endif
typedef struct {
BlockDriverAIOCB common;
uint8_t *buf;
void *orig_buf;
} VdiAIOCB;
typedef struct {
char text[0x40];
uint32_t signature;
@ -472,31 +466,9 @@ static int coroutine_fn vdi_co_is_allocated(BlockDriverState *bs,
return VDI_IS_ALLOCATED(bmap_entry);
}
static AIOPool vdi_aio_pool = {
.aiocb_size = sizeof(VdiAIOCB),
};
static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, QEMUIOVector *qiov)
static int vdi_co_read(BlockDriverState *bs,
int64_t sector_num, uint8_t *buf, int nb_sectors)
{
VdiAIOCB *acb;
logout("%p, %p\n", bs, qiov);
acb = qemu_aio_get(&vdi_aio_pool, bs, NULL, NULL);
if (qiov->niov > 1) {
acb->buf = qemu_blockalign(bs, qiov->size);
acb->orig_buf = acb->buf;
} else {
acb->buf = (uint8_t *)qiov->iov->iov_base;
}
return acb;
}
static int vdi_co_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
VdiAIOCB *acb;
BDRVVdiState *s = bs->opaque;
uint32_t bmap_entry;
uint32_t block_index;
@ -507,7 +479,6 @@ static int vdi_co_readv(BlockDriverState *bs,
int ret;
logout("\n");
acb = vdi_aio_setup(bs, qiov);
restart:
block_index = sector_num / s->block_sectors;
@ -524,13 +495,13 @@ restart:
bmap_entry = le32_to_cpu(s->bmap[block_index]);
if (!VDI_IS_ALLOCATED(bmap_entry)) {
/* Block not allocated, return zeros, no need to wait. */
memset(acb->buf, 0, n_sectors * SECTOR_SIZE);
memset(buf, 0, n_sectors * SECTOR_SIZE);
ret = 0;
} else {
uint64_t offset = s->header.offset_data / SECTOR_SIZE +
(uint64_t)bmap_entry * s->block_sectors +
sector_in_block;
hd_iov.iov_base = (void *)acb->buf;
hd_iov.iov_base = (void *)buf;
hd_iov.iov_len = n_sectors * SECTOR_SIZE;
qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
ret = bdrv_co_readv(bs->file, offset, n_sectors, &hd_qiov);
@ -539,24 +510,18 @@ restart:
nb_sectors -= n_sectors;
sector_num += n_sectors;
acb->buf += n_sectors * SECTOR_SIZE;
buf += n_sectors * SECTOR_SIZE;
if (ret >= 0 && nb_sectors > 0) {
goto restart;
}
if (acb->orig_buf) {
qemu_iovec_from_buffer(qiov, acb->orig_buf, qiov->size);
qemu_vfree(acb->orig_buf);
}
qemu_aio_release(acb);
return ret;
}
static int vdi_co_writev(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
static int vdi_co_write(BlockDriverState *bs,
int64_t sector_num, const uint8_t *buf, int nb_sectors)
{
VdiAIOCB *acb;
BDRVVdiState *s = bs->opaque;
uint32_t bmap_entry;
uint32_t block_index;
@ -570,10 +535,6 @@ static int vdi_co_writev(BlockDriverState *bs,
int ret;
logout("\n");
acb = vdi_aio_setup(bs, qiov);
if (acb->orig_buf) {
qemu_iovec_to_buffer(qiov, acb->buf);
}
restart:
block_index = sector_num / s->block_sectors;
@ -604,7 +565,7 @@ restart:
/* Copy data to be written to new block and zero unused parts. */
memset(block, 0, sector_in_block * SECTOR_SIZE);
memcpy(block + sector_in_block * SECTOR_SIZE,
acb->buf, n_sectors * SECTOR_SIZE);
buf, n_sectors * SECTOR_SIZE);
memset(block + (sector_in_block + n_sectors) * SECTOR_SIZE, 0,
(s->block_sectors - n_sectors - sector_in_block) * SECTOR_SIZE);
hd_iov.iov_base = (void *)block;
@ -615,7 +576,7 @@ restart:
uint64_t offset = s->header.offset_data / SECTOR_SIZE +
(uint64_t)bmap_entry * s->block_sectors +
sector_in_block;
hd_iov.iov_base = (void *)acb->buf;
hd_iov.iov_base = (void *)buf;
hd_iov.iov_len = n_sectors * SECTOR_SIZE;
qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
ret = bdrv_co_writev(bs->file, offset, n_sectors, &hd_qiov);
@ -623,7 +584,7 @@ restart:
nb_sectors -= n_sectors;
sector_num += n_sectors;
acb->buf += n_sectors * SECTOR_SIZE;
buf += n_sectors * SECTOR_SIZE;
logout("%u sectors written\n", n_sectors);
if (ret >= 0 && nb_sectors > 0) {
@ -666,10 +627,6 @@ restart:
}
}
if (acb->orig_buf) {
qemu_vfree(acb->orig_buf);
}
qemu_aio_release(acb);
return ret;
}
@ -821,9 +778,9 @@ static BlockDriver bdrv_vdi = {
.bdrv_co_is_allocated = vdi_co_is_allocated,
.bdrv_make_empty = vdi_make_empty,
.bdrv_co_readv = vdi_co_readv,
.bdrv_read = vdi_co_read,
#if defined(CONFIG_VDI_WRITE)
.bdrv_co_writev = vdi_co_writev,
.bdrv_write = vdi_co_write,
#endif
.bdrv_get_info = vdi_get_info,