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dmg: Implement .bdrv_co_preadv() interface 

This implements .bdrv_co_preadv() for the cloop block driver. While
updating the error paths, change -1 to a valid -errno code.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
master
Kevin Wolf 2016-04-25 15:43:09 +02:00
parent 5cd230819e
commit 3edf1e73d5
1 changed files with 23 additions and 17 deletions
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40
block/dmg.c
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@ -440,6 +440,8 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
int ret;
bs->read_only = 1;
bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
s->n_chunks = 0;
s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
/* used by dmg_read_mish_block to keep track of the current I/O position */
@ -659,38 +661,42 @@ static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
return 0;
}
static int dmg_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
static int coroutine_fn
dmg_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
BDRVDMGState *s = bs->opaque;
int i;
uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
int nb_sectors = bytes >> BDRV_SECTOR_BITS;
int ret, i;
assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
qemu_co_mutex_lock(&s->lock);
for (i = 0; i < nb_sectors; i++) {
uint32_t sector_offset_in_chunk;
void *data;
if (dmg_read_chunk(bs, sector_num + i) != 0) {
return -1;
ret = -EIO;
goto fail;
}
/* Special case: current chunk is all zeroes. Do not perform a memcpy as
* s->uncompressed_chunk may be too small to cover the large all-zeroes
* section. dmg_read_chunk is called to find s->current_chunk */
if (s->types[s->current_chunk] == 2) { /* all zeroes block entry */
memset(buf + i * 512, 0, 512);
qemu_iovec_memset(qiov, i * 512, 0, 512);
continue;
}
sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
memcpy(buf + i * 512,
s->uncompressed_chunk + sector_offset_in_chunk * 512, 512);
data = s->uncompressed_chunk + sector_offset_in_chunk * 512;
qemu_iovec_from_buf(qiov, i * 512, data, 512);
}
return 0;
}
static coroutine_fn int dmg_co_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
int ret;
BDRVDMGState *s = bs->opaque;
qemu_co_mutex_lock(&s->lock);
ret = dmg_read(bs, sector_num, buf, nb_sectors);
ret = 0;
fail:
qemu_co_mutex_unlock(&s->lock);
return ret;
}
@ -715,7 +721,7 @@ static BlockDriver bdrv_dmg = {
.instance_size = sizeof(BDRVDMGState),
.bdrv_probe = dmg_probe,
.bdrv_open = dmg_open,
.bdrv_read = dmg_co_read,
.bdrv_co_preadv = dmg_co_preadv,
.bdrv_close = dmg_close,
};