diff options
| -rw-r--r-- | block/qcow2.c | 46 | ||||
| -rw-r--r-- | block/qcow2.h | 6 |
2 files changed, 48 insertions, 4 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index 4fa3ff9..21ed6f8 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -140,7 +140,7 @@ static int qcow_read_extensions(BlockDriverState *bs, uint64_t start_offset, static int qcow_open(BlockDriverState *bs, int flags) { BDRVQcowState *s = bs->opaque; - int len, i, shift; + int len, i; QCowHeader header; uint64_t ext_end; @@ -188,8 +188,7 @@ static int qcow_open(BlockDriverState *bs, int flags) /* read the level 1 table */ s->l1_size = header.l1_size; - shift = s->cluster_bits + s->l2_bits; - s->l1_vm_state_index = (header.size + (1LL << shift) - 1) >> shift; + s->l1_vm_state_index = size_to_l1(s, header.size); /* the L1 table must contain at least enough entries to put header.size bytes */ if (s->l1_size < s->l1_vm_state_index) @@ -851,6 +850,43 @@ static int qcow_make_empty(BlockDriverState *bs) return 0; } +static int qcow2_truncate(BlockDriverState *bs, int64_t offset) +{ + BDRVQcowState *s = bs->opaque; + int ret, new_l1_size; + + if (offset & 511) { + return -EINVAL; + } + + /* cannot proceed if image has snapshots */ + if (s->nb_snapshots) { + return -ENOTSUP; + } + + /* shrinking is currently not supported */ + if (offset < bs->total_sectors * 512) { + return -ENOTSUP; + } + + new_l1_size = size_to_l1(s, offset); + ret = qcow2_grow_l1_table(bs, new_l1_size); + if (ret < 0) { + return ret; + } + + /* write updated header.size */ + offset = cpu_to_be64(offset); + ret = bdrv_pwrite(bs->file, offsetof(QCowHeader, size), + &offset, sizeof(uint64_t)); + if (ret < 0) { + return ret; + } + + s->l1_vm_state_index = new_l1_size; + return 0; +} + /* XXX: put compressed sectors first, then all the cluster aligned tables to avoid losing bytes in alignment */ static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num, @@ -1050,7 +1086,9 @@ static BlockDriver bdrv_qcow2 = { .bdrv_aio_readv = qcow_aio_readv, .bdrv_aio_writev = qcow_aio_writev, .bdrv_aio_flush = qcow_aio_flush, - .bdrv_write_compressed = qcow_write_compressed, + + .bdrv_truncate = qcow2_truncate, + .bdrv_write_compressed = qcow_write_compressed, .bdrv_snapshot_create = qcow2_snapshot_create, .bdrv_snapshot_goto = qcow2_snapshot_goto, diff --git a/block/qcow2.h b/block/qcow2.h index 5bd08db..01053b7 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -150,6 +150,12 @@ static inline int size_to_clusters(BDRVQcowState *s, int64_t size) return (size + (s->cluster_size - 1)) >> s->cluster_bits; } +static inline int size_to_l1(BDRVQcowState *s, int64_t size) +{ + int shift = s->cluster_bits + s->l2_bits; + return (size + (1ULL << shift) - 1) >> shift; +} + static inline int64_t align_offset(int64_t offset, int n) { offset = (offset + n - 1) & ~(n - 1); |