From b6c246942b14d3e0dec46a6c5868ed84e7dbea19 Mon Sep 17 00:00:00 2001 From: Alberto Garcia Date: Fri, 10 May 2019 19:22:54 +0300 Subject: [PATCH] qcow2: Define and use QCOW2_COMPRESSED_SECTOR_SIZE When an L2 table entry points to a compressed cluster the space used by the data is specified in 512-byte sectors. This size is independent from BDRV_SECTOR_SIZE and is specific to the qcow2 file format. The QCOW2_COMPRESSED_SECTOR_SIZE constant defined in this patch makes this explicit. Signed-off-by: Alberto Garcia Signed-off-by: Kevin Wolf --- block/qcow2-cluster.c | 5 +++-- block/qcow2-refcount.c | 25 ++++++++++++++----------- block/qcow2.c | 3 ++- block/qcow2.h | 4 ++++ 4 files changed, 23 insertions(+), 14 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 974a4e8656..b36f4aa84a 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -796,8 +796,9 @@ int qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs, return cluster_offset; } - nb_csectors = ((cluster_offset + compressed_size - 1) >> 9) - - (cluster_offset >> 9); + nb_csectors = + (cluster_offset + compressed_size - 1) / QCOW2_COMPRESSED_SECTOR_SIZE - + (cluster_offset / QCOW2_COMPRESSED_SECTOR_SIZE); cluster_offset |= QCOW_OFLAG_COMPRESSED | ((uint64_t)nb_csectors << s->csize_shift); diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 7481903396..0b09d6838b 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -1172,12 +1172,11 @@ void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry, switch (ctype) { case QCOW2_CLUSTER_COMPRESSED: { - int nb_csectors; - nb_csectors = ((l2_entry >> s->csize_shift) & - s->csize_mask) + 1; - qcow2_free_clusters(bs, - (l2_entry & s->cluster_offset_mask) & ~511, - nb_csectors * 512, type); + int64_t offset = (l2_entry & s->cluster_offset_mask) + & QCOW2_COMPRESSED_SECTOR_MASK; + int size = QCOW2_COMPRESSED_SECTOR_SIZE * + (((l2_entry >> s->csize_shift) & s->csize_mask) + 1); + qcow2_free_clusters(bs, offset, size, type); } break; case QCOW2_CLUSTER_NORMAL: @@ -1317,9 +1316,12 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs, nb_csectors = ((entry >> s->csize_shift) & s->csize_mask) + 1; if (addend != 0) { + uint64_t coffset = (entry & s->cluster_offset_mask) + & QCOW2_COMPRESSED_SECTOR_MASK; ret = update_refcount( - bs, (entry & s->cluster_offset_mask) & ~511, - nb_csectors * 512, abs(addend), addend < 0, + bs, coffset, + nb_csectors * QCOW2_COMPRESSED_SECTOR_SIZE, + abs(addend), addend < 0, QCOW2_DISCARD_SNAPSHOT); if (ret < 0) { goto fail; @@ -1635,9 +1637,10 @@ static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res, nb_csectors = ((l2_entry >> s->csize_shift) & s->csize_mask) + 1; l2_entry &= s->cluster_offset_mask; - ret = qcow2_inc_refcounts_imrt(bs, res, - refcount_table, refcount_table_size, - l2_entry & ~511, nb_csectors * 512); + ret = qcow2_inc_refcounts_imrt( + bs, res, refcount_table, refcount_table_size, + l2_entry & QCOW2_COMPRESSED_SECTOR_MASK, + nb_csectors * QCOW2_COMPRESSED_SECTOR_SIZE); if (ret < 0) { goto fail; } diff --git a/block/qcow2.c b/block/qcow2.c index 8e024007db..d39882785d 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -4187,7 +4187,8 @@ qcow2_co_preadv_compressed(BlockDriverState *bs, coffset = file_cluster_offset & s->cluster_offset_mask; nb_csectors = ((file_cluster_offset >> s->csize_shift) & s->csize_mask) + 1; - csize = nb_csectors * 512 - (coffset & 511); + csize = nb_csectors * QCOW2_COMPRESSED_SECTOR_SIZE - + (coffset & ~QCOW2_COMPRESSED_SECTOR_MASK); buf = g_try_malloc(csize); if (!buf) { diff --git a/block/qcow2.h b/block/qcow2.h index e62508d1ce..8d92ef1fee 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -74,6 +74,10 @@ #define MIN_CLUSTER_BITS 9 #define MAX_CLUSTER_BITS 21 +/* Defined in the qcow2 spec (compressed cluster descriptor) */ +#define QCOW2_COMPRESSED_SECTOR_SIZE 512U +#define QCOW2_COMPRESSED_SECTOR_MASK (~(QCOW2_COMPRESSED_SECTOR_SIZE - 1)) + /* Must be at least 2 to cover COW */ #define MIN_L2_CACHE_SIZE 2 /* cache entries */