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author | Eric Blake <eblake@redhat.com> | 2017-10-11 22:47:00 -0500 |
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committer | Kevin Wolf <kwolf@redhat.com> | 2017-10-26 14:45:57 +0200 |
commit | f06f6b66c789c41165b46f98c88141b955cd594d (patch) | |
tree | c802d33b99c3811910a878bbf5f86bca70fe20eb | |
parent | 7cfd527525a7d6b1c904890a6b84c1227846415e (diff) | |
download | qemu-f06f6b66c789c41165b46f98c88141b955cd594d.zip qemu-f06f6b66c789c41165b46f98c88141b955cd594d.tar.gz qemu-f06f6b66c789c41165b46f98c88141b955cd594d.tar.bz2 |
qcow2: Switch is_zero_sectors() to byte-based
We are gradually converting to byte-based interfaces, as they are
easier to reason about than sector-based. Convert another internal
function (no semantic change), and rename it to is_zero() in the
process.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r-- | block/qcow2.c | 33 |
1 files changed, 19 insertions, 14 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index 0e4c91c..795be67 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2972,21 +2972,29 @@ finish: } -static bool is_zero_sectors(BlockDriverState *bs, int64_t start, - uint32_t count) +static bool is_zero(BlockDriverState *bs, int64_t offset, int64_t bytes) { int nr; int64_t res; + int64_t start; - if (start + count > bs->total_sectors) { - count = bs->total_sectors - start; + /* TODO: Widening to sector boundaries should only be needed as + * long as we can't query finer granularity. */ + start = QEMU_ALIGN_DOWN(offset, BDRV_SECTOR_SIZE); + bytes = QEMU_ALIGN_UP(offset + bytes, BDRV_SECTOR_SIZE) - start; + + /* Clamp to image length, before checking status of underlying sectors */ + if (start + bytes > bs->total_sectors * BDRV_SECTOR_SIZE) { + bytes = bs->total_sectors * BDRV_SECTOR_SIZE - start; } - if (!count) { + if (!bytes) { return true; } - res = bdrv_get_block_status_above(bs, NULL, start, count, &nr, NULL); - return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == count; + res = bdrv_get_block_status_above(bs, NULL, start >> BDRV_SECTOR_BITS, + bytes >> BDRV_SECTOR_BITS, &nr, NULL); + return res >= 0 && (res & BDRV_BLOCK_ZERO) && + nr * BDRV_SECTOR_SIZE == bytes; } static coroutine_fn int qcow2_co_pwrite_zeroes(BlockDriverState *bs, @@ -3004,24 +3012,21 @@ static coroutine_fn int qcow2_co_pwrite_zeroes(BlockDriverState *bs, } if (head || tail) { - int64_t cl_start = (offset - head) >> BDRV_SECTOR_BITS; uint64_t off; unsigned int nr; assert(head + bytes <= s->cluster_size); /* check whether remainder of cluster already reads as zero */ - if (!(is_zero_sectors(bs, cl_start, - DIV_ROUND_UP(head, BDRV_SECTOR_SIZE)) && - is_zero_sectors(bs, (offset + bytes) >> BDRV_SECTOR_BITS, - DIV_ROUND_UP(-tail & (s->cluster_size - 1), - BDRV_SECTOR_SIZE)))) { + if (!(is_zero(bs, offset - head, head) && + is_zero(bs, offset + bytes, + tail ? s->cluster_size - tail : 0))) { return -ENOTSUP; } qemu_co_mutex_lock(&s->lock); /* We can have new write after previous check */ - offset = cl_start << BDRV_SECTOR_BITS; + offset = QEMU_ALIGN_DOWN(offset, s->cluster_size); bytes = s->cluster_size; nr = s->cluster_size; ret = qcow2_get_cluster_offset(bs, offset, &nr, &off); |