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vdi: Implement .bdrv_co_pwritev() interface

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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
This commit is contained in:
Kevin Wolf 2016-04-25 16:22:39 +02:00
parent 0865bb6f04
commit fde9d56f5b
1 changed files with 41 additions and 31 deletions
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72
block/vdi.c
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@ -611,53 +611,55 @@ vdi_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
return ret;
}
static int vdi_co_write(BlockDriverState *bs,
int64_t sector_num, const uint8_t *buf, int nb_sectors)
static int coroutine_fn
vdi_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
BDRVVdiState *s = bs->opaque;
QEMUIOVector local_qiov;
uint32_t bmap_entry;
uint32_t block_index;
uint32_t sector_in_block;
uint32_t n_sectors;
uint32_t offset_in_block;
uint32_t n_bytes;
uint32_t bmap_first = VDI_UNALLOCATED;
uint32_t bmap_last = VDI_UNALLOCATED;
uint8_t *block = NULL;
uint64_t bytes_done = 0;
int ret = 0;
logout("\n");
while (ret >= 0 && nb_sectors > 0) {
block_index = sector_num / s->block_sectors;
sector_in_block = sector_num % s->block_sectors;
n_sectors = s->block_sectors - sector_in_block;
if (n_sectors > nb_sectors) {
n_sectors = nb_sectors;
}
qemu_iovec_init(&local_qiov, qiov->niov);
logout("will write %u sectors starting at sector %" PRIu64 "\n",
n_sectors, sector_num);
while (ret >= 0 && bytes > 0) {
block_index = offset / s->block_size;
offset_in_block = offset % s->block_size;
n_bytes = MIN(bytes, s->block_size - offset_in_block);
logout("will write %u bytes starting at offset %" PRIu64 "\n",
n_bytes, offset);
/* prepare next AIO request */
bmap_entry = le32_to_cpu(s->bmap[block_index]);
if (!VDI_IS_ALLOCATED(bmap_entry)) {
/* Allocate new block and write to it. */
uint64_t offset;
uint64_t data_offset;
bmap_entry = s->header.blocks_allocated;
s->bmap[block_index] = cpu_to_le32(bmap_entry);
s->header.blocks_allocated++;
offset = s->header.offset_data / SECTOR_SIZE +
(uint64_t)bmap_entry * s->block_sectors;
data_offset = s->header.offset_data +
(uint64_t)bmap_entry * s->block_size;
if (block == NULL) {
block = g_malloc(s->block_size);
bmap_first = block_index;
}
bmap_last = block_index;
/* 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,
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);
memset(block, 0, offset_in_block);
qemu_iovec_to_buf(qiov, bytes_done, block + offset_in_block,
n_bytes);
memset(block + offset_in_block + n_bytes, 0,
s->block_size - n_bytes - offset_in_block);
/* Note that this coroutine does not yield anywhere from reading the
* bmap entry until here, so in regards to all the coroutines trying
@ -667,12 +669,12 @@ static int vdi_co_write(BlockDriverState *bs,
* acquire the lock and thus the padded cluster is written before
* the other coroutines can write to the affected area. */
qemu_co_mutex_lock(&s->write_lock);
ret = bdrv_write(bs->file->bs, offset, block, s->block_sectors);
ret = bdrv_pwrite(bs->file->bs, data_offset, block, s->block_size);
qemu_co_mutex_unlock(&s->write_lock);
} else {
uint64_t offset = s->header.offset_data / SECTOR_SIZE +
(uint64_t)bmap_entry * s->block_sectors +
sector_in_block;
uint64_t data_offset = s->header.offset_data +
(uint64_t)bmap_entry * s->block_size +
offset_in_block;
qemu_co_mutex_lock(&s->write_lock);
/* This lock is only used to make sure the following write operation
* is executed after the write issued by the coroutine allocating
@ -683,16 +685,23 @@ static int vdi_co_write(BlockDriverState *bs,
* that that write operation has returned (there may be other writes
* in flight, but they do not concern this very operation). */
qemu_co_mutex_unlock(&s->write_lock);
ret = bdrv_write(bs->file->bs, offset, buf, n_sectors);
qemu_iovec_reset(&local_qiov);
qemu_iovec_concat(&local_qiov, qiov, bytes_done, n_bytes);
ret = bdrv_co_pwritev(bs->file->bs, data_offset, n_bytes,
&local_qiov, 0);
}
nb_sectors -= n_sectors;
sector_num += n_sectors;
buf += n_sectors * SECTOR_SIZE;
bytes -= n_bytes;
offset += n_bytes;
bytes_done += n_bytes;
logout("%u sectors written\n", n_sectors);
logout("%u bytes written\n", n_bytes);
}
qemu_iovec_destroy(&local_qiov);
logout("finished data write\n");
if (ret < 0) {
return ret;
@ -703,6 +712,7 @@ static int vdi_co_write(BlockDriverState *bs,
VdiHeader *header = (VdiHeader *) block;
uint8_t *base;
uint64_t offset;
uint32_t n_sectors;
logout("now writing modified header\n");
assert(VDI_IS_ALLOCATED(bmap_first));
@ -914,7 +924,7 @@ static BlockDriver bdrv_vdi = {
.bdrv_co_preadv = vdi_co_preadv,
#if defined(CONFIG_VDI_WRITE)
.bdrv_write = vdi_co_write,
.bdrv_co_pwritev = vdi_co_pwritev,
#endif
.bdrv_get_info = vdi_get_info,