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From: | Vladimir Sementsov-Ogievskiy |
Subject: | Re: [PATCH v3 1/2] qcow2: Report BDRV_BLOCK_ZERO more accurately in bdrv_co_block_status() |
Date: | Fri, 11 Sep 2020 12:14:02 +0300 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 |
10.09.2020 20:46, Alberto Garcia wrote:
If a BlockDriverState supports backing files but has none then any unallocated area reads back as zeroes. bdrv_co_block_status() is only reporting this is if want_zero is true, but this is an inexpensive test and there is no reason not to do it in all cases. Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
--- block/io.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/block/io.c b/block/io.c index ad3a51ed53..1b0ae29610 100644 --- a/block/io.c +++ b/block/io.c @@ -2408,16 +2408,16 @@ static int coroutine_fn bdrv_co_block_status(BlockDriverState *bs,if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) {ret |= BDRV_BLOCK_ALLOCATED; - } else if (want_zero && bs->drv->supports_backing) { - if (bs->backing) { + } else if (bs->drv->supports_backing) { + if (!bs->backing) { + ret |= BDRV_BLOCK_ZERO; + } else if (want_zero) { BlockDriverState *bs2 = bs->backing->bs; int64_t size2 = bdrv_getlength(bs2);if (size2 >= 0 && offset >= size2) {ret |= BDRV_BLOCK_ZERO; } - } else { - ret |= BDRV_BLOCK_ZERO; } }
-- Best regards, Vladimir
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