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block: Add bdrv_get_block_status_above 

Like bdrv_is_allocated_above, this function follows the backing chain until seeing
BDRV_BLOCK_ALLOCATED.  Base is not included.

Reimplement bdrv_is_allocated on top.

[Initialized bdrv_co_get_block_status_above() ret to 0 to silence
mingw64 compiler warning about the unitialized variable.  assert(bs !=
base) prevents that case but I suppose the program could be compiled
with -DNDEBUG.
--Stefan]

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Fam Zheng 2015-06-08 13:56:07 +08:00 committed by Stefan Hajnoczi
parent e0cf11f31c
commit ba3f0e2545
2 changed files with 49 additions and 11 deletions
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56
block/io.c
View File

@ -1531,28 +1531,54 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
return ret;
}
/* Coroutine wrapper for bdrv_get_block_status() */
static void coroutine_fn bdrv_get_block_status_co_entry(void *opaque)
static int64_t coroutine_fn bdrv_co_get_block_status_above(BlockDriverState *bs,
BlockDriverState *base,
int64_t sector_num,
int nb_sectors,
int *pnum)
{
BlockDriverState *p;
int64_t ret = 0;
assert(bs != base);
for (p = bs; p != base; p = p->backing_hd) {
ret = bdrv_co_get_block_status(p, sector_num, nb_sectors, pnum);
if (ret < 0 || ret & BDRV_BLOCK_ALLOCATED) {
break;
}
/* [sector_num, pnum] unallocated on this layer, which could be only
* the first part of [sector_num, nb_sectors]. */
nb_sectors = MIN(nb_sectors, *pnum);
}
return ret;
}
/* Coroutine wrapper for bdrv_get_block_status_above() */
static void coroutine_fn bdrv_get_block_status_above_co_entry(void *opaque)
{
BdrvCoGetBlockStatusData *data = opaque;
BlockDriverState *bs = data->bs;
data->ret = bdrv_co_get_block_status(bs, data->sector_num, data->nb_sectors,
data->pnum);
data->ret = bdrv_co_get_block_status_above(data->bs, data->base,
data->sector_num,
data->nb_sectors,
data->pnum);
data->done = true;
}
/*
* Synchronous wrapper around bdrv_co_get_block_status().
* Synchronous wrapper around bdrv_co_get_block_status_above().
*
* See bdrv_co_get_block_status() for details.
* See bdrv_co_get_block_status_above() for details.
*/
int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
int64_t bdrv_get_block_status_above(BlockDriverState *bs,
BlockDriverState *base,
int64_t sector_num,
int nb_sectors, int *pnum)
{
Coroutine *co;
BdrvCoGetBlockStatusData data = {
.bs = bs,
.base = base,
.sector_num = sector_num,
.nb_sectors = nb_sectors,
.pnum = pnum,
@ -1561,11 +1587,11 @@ int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_get_block_status_co_entry(&data);
bdrv_get_block_status_above_co_entry(&data);
} else {
AioContext *aio_context = bdrv_get_aio_context(bs);
co = qemu_coroutine_create(bdrv_get_block_status_co_entry);
co = qemu_coroutine_create(bdrv_get_block_status_above_co_entry);
qemu_coroutine_enter(co, &data);
while (!data.done) {
aio_poll(aio_context, true);
@ -1574,6 +1600,14 @@ int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
return data.ret;
}
int64_t bdrv_get_block_status(BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, int *pnum)
{
return bdrv_get_block_status_above(bs, bs->backing_hd,
sector_num, nb_sectors, pnum);
}
int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
{

4
include/block/block.h
View File

@ -372,6 +372,10 @@ bool bdrv_unallocated_blocks_are_zero(BlockDriverState *bs);
bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs);
int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum);
int64_t bdrv_get_block_status_above(BlockDriverState *bs,
BlockDriverState *base,
int64_t sector_num,
int nb_sectors, int *pnum);
int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
int *pnum);
int bdrv_is_allocated_above(BlockDriverState *top, BlockDriverState *base,