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vdi: do not create useless iovecs 

Reads and writes to the underlying file can also occur with the simple
non-vectored I/O interfaces.

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 18:07:50 +01:00 committed by Kevin Wolf
parent a7a43aa199
commit 4eea78e634
1 changed files with 33 additions and 46 deletions
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79
block/vdi.c
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@ -474,8 +474,6 @@ static int vdi_co_read(BlockDriverState *bs,
uint32_t block_index;
uint32_t sector_in_block;
uint32_t n_sectors;
struct iovec hd_iov;
QEMUIOVector hd_qiov;
int ret;
logout("\n");
@ -501,10 +499,7 @@ 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 *)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);
ret = bdrv_read(bs->file, offset, buf, n_sectors);
}
logout("%u sectors read\n", n_sectors);
@ -529,8 +524,6 @@ static int vdi_co_write(BlockDriverState *bs,
uint32_t n_sectors;
uint32_t bmap_first = VDI_UNALLOCATED;
uint32_t bmap_last = VDI_UNALLOCATED;
struct iovec hd_iov;
QEMUIOVector hd_qiov;
uint8_t *block = NULL;
int ret;
@ -568,18 +561,12 @@ restart:
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;
hd_iov.iov_len = s->block_size;
qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
ret = bdrv_co_writev(bs->file, offset, s->block_sectors, &hd_qiov);
ret = bdrv_write(bs->file, offset, block, s->block_sectors);
} 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 *)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);
ret = bdrv_write(bs->file, offset, buf, n_sectors);
}
nb_sectors -= n_sectors;
@ -592,39 +579,39 @@ restart:
}
logout("finished data write\n");
if (ret >= 0) {
ret = 0;
if (block) {
VdiHeader *header = (VdiHeader *) block;
logout("now writing modified header\n");
assert(VDI_IS_ALLOCATED(bmap_first));
*header = s->header;
vdi_header_to_le(header);
hd_iov.iov_base = block;
hd_iov.iov_len = SECTOR_SIZE;
qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
ret = bdrv_co_writev(bs->file, 0, 1, &hd_qiov);
}
if (ret < 0) {
return ret;
}
if (block) {
/* One or more new blocks were allocated. */
VdiHeader *header = (VdiHeader *) block;
uint8_t *base;
uint64_t offset;
logout("now writing modified header\n");
assert(VDI_IS_ALLOCATED(bmap_first));
*header = s->header;
vdi_header_to_le(header);
ret = bdrv_write(bs->file, 0, block, 1);
g_free(block);
block = NULL;
if (ret >= 0 && VDI_IS_ALLOCATED(bmap_first)) {
/* One or more new blocks were allocated. */
uint64_t offset;
logout("now writing modified block map entry %u...%u\n",
bmap_first, bmap_last);
/* Write modified sectors from block map. */
bmap_first /= (SECTOR_SIZE / sizeof(uint32_t));
bmap_last /= (SECTOR_SIZE / sizeof(uint32_t));
n_sectors = bmap_last - bmap_first + 1;
offset = s->bmap_sector + bmap_first;
hd_iov.iov_base = (void *)((uint8_t *)&s->bmap[0] +
bmap_first * SECTOR_SIZE);
hd_iov.iov_len = n_sectors * SECTOR_SIZE;
qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
logout("will write %u block map sectors starting from entry %u\n",
n_sectors, bmap_first);
ret = bdrv_co_writev(bs->file, offset, n_sectors, &hd_qiov);
if (ret < 0) {
return ret;
}
logout("now writing modified block map entry %u...%u\n",
bmap_first, bmap_last);
/* Write modified sectors from block map. */
bmap_first /= (SECTOR_SIZE / sizeof(uint32_t));
bmap_last /= (SECTOR_SIZE / sizeof(uint32_t));
n_sectors = bmap_last - bmap_first + 1;
offset = s->bmap_sector + bmap_first;
base = ((uint8_t *)&s->bmap[0]) + bmap_first * SECTOR_SIZE;
logout("will write %u block map sectors starting from entry %u\n",
n_sectors, bmap_first);
ret = bdrv_write(bs->file, offset, base, n_sectors);
}
return ret;