From 787993a5435289e90479f80f81681c804a9d22ce Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Thu, 28 Jun 2018 15:15:19 -0500 Subject: [PATCH] qcow: Switch get_cluster_offset to be byte-based We are gradually moving away from sector-based interfaces, towards byte-based. Make the change for the internal helper function get_cluster_offset(), by changing n_start and n_end to be byte offsets rather than sector indices within the cluster being allocated. However, assert that these values are still sector-aligned (at least qcrypto_block_encrypt() still wants that). For now we get that alignment for free because we still use sector-based driver callbacks. A later patch will then switch the qcow driver as a whole over to byte-based operation; but will still leave things at sector alignments as it is not worth auditing the qcow image format to worry about sub-sector requests. Signed-off-by: Eric Blake Reviewed-by: Jeff Cody Signed-off-by: Kevin Wolf --- block/qcow.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-) diff --git a/block/qcow.c b/block/qcow.c index 8546fe5bb7..d7c385a91d 100644 --- a/block/qcow.c +++ b/block/qcow.c @@ -345,8 +345,8 @@ static int qcow_reopen_prepare(BDRVReopenState *state, * * 0 to not allocate. * - * 1 to allocate a normal cluster (for sector indexes 'n_start' to - * 'n_end') + * 1 to allocate a normal cluster (for sector-aligned byte offsets 'n_start' + * to 'n_end' within the cluster) * * 2 to allocate a compressed cluster of size * 'compressed_size'. 'compressed_size' must be > 0 and < @@ -440,9 +440,10 @@ static int get_cluster_offset(BlockDriverState *bs, if (!allocate) return 0; BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC); + assert(QEMU_IS_ALIGNED(n_start | n_end, BDRV_SECTOR_SIZE)); /* allocate a new cluster */ if ((cluster_offset & QCOW_OFLAG_COMPRESSED) && - (n_end - n_start) < s->cluster_sectors) { + (n_end - n_start) < s->cluster_size) { /* if the cluster is already compressed, we must decompress it in the case it is not completely overwritten */ @@ -480,16 +481,15 @@ static int get_cluster_offset(BlockDriverState *bs, /* if encrypted, we must initialize the cluster content which won't be written */ if (bs->encrypted && - (n_end - n_start) < s->cluster_sectors) { - uint64_t start_sect; + (n_end - n_start) < s->cluster_size) { + uint64_t start_offset; assert(s->crypto); - start_sect = (offset & ~(s->cluster_size - 1)) >> 9; - for(i = 0; i < s->cluster_sectors; i++) { + start_offset = offset & ~(s->cluster_size - 1); + for (i = 0; i < s->cluster_size; i += BDRV_SECTOR_SIZE) { if (i < n_start || i >= n_end) { - memset(s->cluster_data, 0x00, 512); + memset(s->cluster_data, 0x00, BDRV_SECTOR_SIZE); if (qcrypto_block_encrypt(s->crypto, - (start_sect + i) * - BDRV_SECTOR_SIZE, + start_offset + i, s->cluster_data, BDRV_SECTOR_SIZE, NULL) < 0) { @@ -497,8 +497,9 @@ static int get_cluster_offset(BlockDriverState *bs, } BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO); ret = bdrv_pwrite(bs->file, - cluster_offset + i * 512, - s->cluster_data, 512); + cluster_offset + i, + s->cluster_data, + BDRV_SECTOR_SIZE); if (ret < 0) { return ret; } @@ -758,8 +759,8 @@ static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num, n = nb_sectors; } ret = get_cluster_offset(bs, sector_num << 9, 1, 0, - index_in_cluster, - index_in_cluster + n, &cluster_offset); + index_in_cluster << 9, + (index_in_cluster + n) << 9, &cluster_offset); if (ret < 0) { break; } -- 2.11.0