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block: honour BlockLimits in bdrv_co_discard 

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Peter Lieven 2013-10-24 12:06:59 +02:00 committed by Kevin Wolf
parent c31cb70728
commit 6f14da5247
1 changed files with 36 additions and 1 deletions
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37
block.c
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@ -4243,6 +4243,11 @@ static void coroutine_fn bdrv_discard_co_entry(void *opaque)
rwco->ret = bdrv_co_discard(rwco->bs, rwco->sector_num, rwco->nb_sectors);
}
/* if no limit is specified in the BlockLimits use a default
* of 32768 512-byte sectors (16 MiB) per request.
*/
#define MAX_DISCARD_DEFAULT 32768
int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
int nb_sectors)
{
@ -4264,7 +4269,37 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
}
if (bs->drv->bdrv_co_discard) {
return bs->drv->bdrv_co_discard(bs, sector_num, nb_sectors);
int max_discard = bs->bl.max_discard ?
bs->bl.max_discard : MAX_DISCARD_DEFAULT;
while (nb_sectors > 0) {
int ret;
int num = nb_sectors;
/* align request */
if (bs->bl.discard_alignment &&
num >= bs->bl.discard_alignment &&
sector_num % bs->bl.discard_alignment) {
if (num > bs->bl.discard_alignment) {
num = bs->bl.discard_alignment;
}
num -= sector_num % bs->bl.discard_alignment;
}
/* limit request size */
if (num > max_discard) {
num = max_discard;
}
ret = bs->drv->bdrv_co_discard(bs, sector_num, num);
if (ret) {
return ret;
}
sector_num += num;
nb_sectors -= num;
}
return 0;
} else if (bs->drv->bdrv_aio_discard) {
BlockDriverAIOCB *acb;
CoroutineIOCompletion co = {