qcow2 resize with snapshot, i modify the code of shrink size. and some changes for stable and vm state l1 index. thanks for review.
Signed-off-by: zhangzhiming <zhangzhimin...@meituan.com <mailto:zhangzhimin...@meituan.com>> --- block.c | 19 ---------------- block/qcow2-cluster.c | 55 ++++++++++++++++++++++++++++++++++-------------- block/qcow2-snapshot.c | 34 ++++++++++++++-------------- block/qcow2.c | 2 +- block/qcow2.h | 2 +- 5 files changed, 58 insertions(+), 54 deletions(-) diff --git a/block.c b/block.c index 0de7b2d..f54bc25 100644 --- a/block.c +++ b/block.c @@ -2586,25 +2586,6 @@ int bdrv_truncate(BlockDriverState *bs, int64_t offset) return ret; } -int bdrv_apply_snapshot(BlockDriverState *bs, const char *snapshot_id, - uint64_t snapshot_size) -{ - int ret = bdrv_snapshot_goto(bs, snapshot_id); - if (ret < 0) { - return ret; - } - - ret = refresh_total_sectors(bs, snapshot_size >> BDRV_SECTOR_BITS); - if (ret < 0) { - return ret; - } - bdrv_dirty_bitmap_truncate(bs); - if (bs->blk) { - blk_dev_resize_cb(bs->blk); - } - return ret; -} - /** * Length of a allocated file in bytes. Sparse files are counted by actual * allocated space. Return < 0 if error or unknown. diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index ebadddf..2190528 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -32,32 +32,55 @@ #include "qemu/bswap.h" #include "trace.h" -int shrink_l1_table(BlockDriverState *bs, int64_t new_l1_size) +static int free_some_l2_table(BlockDriverState *bs, int64_t old_size, + int64_t new_size) { BDRVQcow2State *s = bs->opaque; - int64_t old_l1_size = s->l1_size; - s->l1_size = new_l1_size; - int ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, - s->l1_size, 1); - if (ret < 0) { - return ret; + int old_l1_size = size_to_l1(s, old_size); + int new_l1_size = size_to_l1(s, new_size); + if (old_l1_size == new_l1_size) { + return 0; } + int i; + for (i = new_l1_size; i < old_l1_size; i++) { + uint64_t l2_offset = s->l1_table[i] & L1E_OFFSET_MASK; + qcow2_free_clusters(bs, l2_offset, s->cluster_size, + QCOW2_DISCARD_OTHER); + s->l1_table[i] = 0; + /* write l1 entry will be called for several times and + * because l1 is short, i think is tolerated! */ + qcow2_write_l1_entry(bs, i); + } + return 0; +} - s->l1_size = old_l1_size; - ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, - s->l1_size, -1); +int shrink_disk(BlockDriverState *bs, int64_t new_size) +{ + BDRVQcow2State *s = bs->opaque; + int64_t old_size = bs->total_sectors * 512; + int64_t new_sector_nb = DIV_ROUND_UP(new_size, 512); + int64_t discard_sectors_nb = bs->total_sectors - new_sector_nb; + int64_t old_cluster_nb = DIV_ROUND_UP(old_size, s->cluster_size); + int64_t new_cluster_nb = DIV_ROUND_UP(new_size, s->cluster_size); + if (old_cluster_nb == new_cluster_nb) { + return 0; + } + s->l1_size = size_to_l1(s, new_size); + bs->total_sectors = new_sector_nb; + int ret = qcow2_update_header(bs); if (ret < 0) { + s->l1_size = size_to_l1(s, old_size); + bs->total_sectors = old_size / 512; return ret; } - s->l1_size = new_l1_size; - uint32_t be_l1_size = cpu_to_be32(s->l1_size); - ret = bdrv_pwrite_sync(bs->file->bs, offsetof(QCowHeader, l1_size), - &be_l1_size, sizeof(be_l1_size)); + /* can't be undone here, if failed nothing will be done */ + ret = qcow2_discard_clusters(bs, new_size, discard_sectors_nb, + QCOW2_DISCARD_OTHER, true); if (ret < 0) { - return ret; + return 0; } - + free_some_l2_table(bs, old_size, new_size); return 0; } diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index 6dd6769..40a0d26 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -490,6 +490,7 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) cur_l1_bytes = s->l1_size * sizeof(uint64_t); sn_l1_bytes = sn->l1_size * sizeof(uint64_t); + int max_l1_size_bytes = MAX(sn_l1_bytes, cur_l1_bytes); /* * Copy the snapshot L1 table to the current L1 table. @@ -499,7 +500,7 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) * Decrease the refcount referenced by the old one only when the L1 * table is overwritten. */ - sn_l1_table = g_try_malloc0(sn_l1_bytes); + sn_l1_table = g_try_malloc0(max_l1_size_bytes); if (sn_l1_bytes && sn_l1_table == NULL) { ret = -ENOMEM; goto fail; @@ -517,34 +518,32 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) goto fail; } - ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1, - s->l1_table_offset, sn_l1_bytes); - if (ret < 0) { - goto fail; - } - - ret = bdrv_pwrite_sync(bs->file->bs, s->l1_table_offset, sn_l1_table, - sn_l1_bytes); + /* update meta data first, for failed */ + int old_l1_size = s->l1_size; + uint64_t old_total_sectors = bs->total_sectors; + bs->total_sectors = sn->disk_size / BDRV_SECTOR_SIZE; + s->l1_size = sn->l1_size; + ret = qcow2_update_header(bs); if (ret < 0) { + s->l1_size = old_l1_size; + bs->total_sectors = old_total_sectors; goto fail; } - /* write updated header.size */ - uint64_t be_disk_size = cpu_to_be64(sn->disk_size); - ret = bdrv_pwrite_sync(bs->file->bs, offsetof(QCowHeader, size), - &be_disk_size, sizeof(uint64_t)); + /* and then update l1 table */ + ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1, + s->l1_table_offset, max_l1_size_bytes); if (ret < 0) { goto fail; } - uint32_t be_l1_size = cpu_to_be32(sn->l1_size); - ret = bdrv_pwrite_sync(bs->file->bs, offsetof(QCowHeader, l1_size), - &be_l1_size, sizeof(be_l1_size)); + ret = bdrv_pwrite_sync(bs->file->bs, s->l1_table_offset, sn_l1_table, + max_l1_size_bytes); if (ret < 0) { goto fail; } - s->l1_vm_state_index = sn->l1_size; + s->l1_vm_state_index = size_to_l1(s, sn->disk_size);; /* * Decrease refcount of clusters of current L1 table. @@ -556,6 +555,7 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) * the in-memory data instead of really using the offset to load a new one, * which is why this works. */ + s->l1_size = old_l1_size; ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1); diff --git a/block/qcow2.c b/block/qcow2.c index 612a534..01a66f2 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2513,7 +2513,7 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t offset) new_l1_size = size_to_l1(s, offset); if (offset < bs->total_sectors * 512) { - ret = shrink_l1_table(bs, new_l1_size); + ret = shrink_disk(bs, offset); if (ret < 0) { return ret; } diff --git a/block/qcow2.h b/block/qcow2.h index 8efa735..ba622b6 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -534,7 +534,7 @@ int qcow2_change_refcount_order(BlockDriverState *bs, int refcount_order, void *cb_opaque, Error **errp); /* qcow2-cluster.c functions */ -int shrink_l1_table(BlockDriverState *bs, int64_t new_l1_size); +int shrink_disk(BlockDriverState *bs, int64_t new_size); int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size, bool exact_size); int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index); -- 1.7.1 zhangzhiming zhangzhimin...@meituan.com <mailto:zhangzhimin...@meituan.com>
