From 6f14da5247076bde1e00444f6d5b2b7ca8075a09 Mon Sep 17 00:00:00 2001 From: Peter Lieven Date: Thu, 24 Oct 2013 12:06:59 +0200 Subject: [PATCH] block: honour BlockLimits in bdrv_co_discard Reviewed-by: Eric Blake Signed-off-by: Peter Lieven Signed-off-by: Stefan Hajnoczi --- block.c | 37 ++++++++++++++++++++++++++++++++++++- 1 file changed, 36 insertions(+), 1 deletion(-) diff --git a/block.c b/block.c index b4194da114d6..df5a60368666 100644 --- a/block.c +++ b/block.c @@ -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 = {