ping zhangzhiming zhangzhimin...@meituan.com
> On Jun 24, 2016, at 7:10 PM, zhangzhiming <zhangzhimin...@meituan.com> wrote: > > qcow2 can’t be resized while there is a snapshot in qcow2 image but in > version 3 image of qcow2, > each disk size of snapshot is stored in the image, so we can resize image > even through this are some snapshots > since version 3 image. the function of resize nearly finished by others, i > just do very little job. > > > Signed-off-by: zhangzhiming <zhangzhimin...@meituan.com > <mailto:zhangzhimin...@meituan.com>> > > --- > block.c | 19 +++++++++++++++++++ > block/qcow2-cluster.c | 29 +++++++++++++++++++++++++++++ > block/qcow2-snapshot.c | 37 +++++++++++++++++++++++++------------ > block/qcow2.c | 29 ++++++++++++++++++++--------- > block/qcow2.h | 1 + > include/block/snapshot.h | 1 + > 6 files changed, 95 insertions(+), 21 deletions(-) > > diff --git a/block.c b/block.c > index f54bc25..0de7b2d 100644 > --- a/block.c > +++ b/block.c > @@ -2586,6 +2586,25 @@ 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 b04bfaf..ebadddf 100644 > --- a/block/qcow2-cluster.c > +++ b/block/qcow2-cluster.c > @@ -32,6 +32,35 @@ > #include "qemu/bswap.h" > #include "trace.h" > > +int shrink_l1_table(BlockDriverState *bs, int64_t new_l1_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; > + } > + > + s->l1_size = old_l1_size; > + ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, > + s->l1_size, -1); > + if (ret < 0) { > + 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)); > + if (ret < 0) { > + return ret; > + } > + > + return 0; > +} > + > int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size, > bool exact_size) > { > diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c > index 242fb21..6dd6769 100644 > --- a/block/qcow2-snapshot.c > +++ b/block/qcow2-snapshot.c > @@ -478,13 +478,6 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char > *snapshot_id) > } > sn = &s->snapshots[snapshot_index]; > > - if (sn->disk_size != bs->total_sectors * BDRV_SECTOR_SIZE) { > - error_report("qcow2: Loading snapshots with different disk " > - "size is not implemented"); > - ret = -ENOTSUP; > - goto fail; > - } > - > /* > * Make sure that the current L1 table is big enough to contain the whole > * L1 table of the snapshot. If the snapshot L1 table is smaller, the > @@ -506,8 +499,8 @@ 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(cur_l1_bytes); > - if (cur_l1_bytes && sn_l1_table == NULL) { > + sn_l1_table = g_try_malloc0(sn_l1_bytes); > + if (sn_l1_bytes && sn_l1_table == NULL) { > ret = -ENOMEM; > goto fail; > } > @@ -525,17 +518,34 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const > char *snapshot_id) > } > > ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1, > - s->l1_table_offset, cur_l1_bytes); > + 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, > - cur_l1_bytes); > + sn_l1_bytes); > + if (ret < 0) { > + 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)); > 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)); > + if (ret < 0) { > + goto fail; > + } > + > + s->l1_vm_state_index = sn->l1_size; > + > /* > * Decrease refcount of clusters of current L1 table. > * > @@ -553,7 +563,8 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char > *snapshot_id) > * Now update the in-memory L1 table to be in sync with the on-disk one. > We > * need to do this even if updating refcounts failed. > */ > - for(i = 0;i < s->l1_size; i++) { > + memset(s->l1_table, 0, s->l1_size * sizeof(uint64_t)); > + for (i = 0; i < sn->l1_size; i++) { > s->l1_table[i] = be64_to_cpu(sn_l1_table[i]); > } > > @@ -564,6 +575,7 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char > *snapshot_id) > g_free(sn_l1_table); > sn_l1_table = NULL; > > + s->l1_size = sn->l1_size; > /* > * Update QCOW_OFLAG_COPIED in the active L1 table (it may have changed > * when we decreased the refcount of the old snapshot. > @@ -676,6 +688,7 @@ int qcow2_snapshot_list(BlockDriverState *bs, > QEMUSnapshotInfo **psn_tab) > sn_info->date_sec = sn->date_sec; > sn_info->date_nsec = sn->date_nsec; > sn_info->vm_clock_nsec = sn->vm_clock_nsec; > + sn_info->disk_size = sn->disk_size; > } > *psn_tab = sn_tab; > return s->nb_snapshots; > diff --git a/block/qcow2.c b/block/qcow2.c > index 6f5fb81..612a534 100644 > --- a/block/qcow2.c > +++ b/block/qcow2.c > @@ -2495,22 +2495,33 @@ static int qcow2_truncate(BlockDriverState *bs, > int64_t offset) > return -EINVAL; > } > > - /* cannot proceed if image has snapshots */ > - if (s->nb_snapshots) { > - error_report("Can't resize an image which has snapshots"); > + bool v3_truncate = (s->qcow_version == 3); > + > + /* cannot proceed if image has snapshots and qcow_version is not 3 */ > + if (!v3_truncate && s->nb_snapshots) { > + error_report("Can't resize an image which has snapshots and " > + "qcow_version is not 3"); > return -ENOTSUP; > } > > - /* shrinking is currently not supported */ > - if (offset < bs->total_sectors * 512) { > - error_report("qcow2 doesn't support shrinking images yet"); > + /* shrinking is supported from version 3 */ > + if (!v3_truncate && offset < bs->total_sectors * 512) { > + error_report("qcow2 doesn't support shrinking images yet while" > + " qcow_version is not 3"); > return -ENOTSUP; > } > > new_l1_size = size_to_l1(s, offset); > - ret = qcow2_grow_l1_table(bs, new_l1_size, true); > - if (ret < 0) { > - return ret; > + if (offset < bs->total_sectors * 512) { > + ret = shrink_l1_table(bs, new_l1_size); > + if (ret < 0) { > + return ret; > + } > + } else { > + ret = qcow2_grow_l1_table(bs, new_l1_size, true); > + if (ret < 0) { > + return ret; > + } > } > > /* write updated header.size */ > diff --git a/block/qcow2.h b/block/qcow2.h > index 7db9795..8efa735 100644 > --- a/block/qcow2.h > +++ b/block/qcow2.h > @@ -534,6 +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 qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size, > bool exact_size); > int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index); > diff --git a/include/block/snapshot.h b/include/block/snapshot.h > index e5c0553..7279c12 100644 > --- a/include/block/snapshot.h > +++ b/include/block/snapshot.h > @@ -44,6 +44,7 @@ typedef struct QEMUSnapshotInfo { > uint32_t date_sec; /* UTC date of the snapshot */ > uint32_t date_nsec; > uint64_t vm_clock_nsec; /* VM clock relative to boot */ > + uint64_t disk_size; > } QEMUSnapshotInfo; > > int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info, > -- > 1.7.1 > >
