diff options
| -rw-r--r-- | block/vhdx.c | 121 |
1 files changed, 80 insertions, 41 deletions
diff --git a/block/vhdx.c b/block/vhdx.c index 7da149a..7bf7cd6 100644 --- a/block/vhdx.c +++ b/block/vhdx.c @@ -248,6 +248,14 @@ static void vhdx_region_unregister_all(BDRVVHDXState *s) } } +static void vhdx_set_shift_bits(BDRVVHDXState *s) +{ + s->logical_sector_size_bits = 31 - clz32(s->logical_sector_size); + s->sectors_per_block_bits = 31 - clz32(s->sectors_per_block); + s->chunk_ratio_bits = 63 - clz64(s->chunk_ratio); + s->block_size_bits = 31 - clz32(s->block_size); +} + /* * Per the MS VHDX Specification, for every VHDX file: * - The header section is fixed size - 1 MB @@ -267,6 +275,50 @@ static int vhdx_probe(const uint8_t *buf, int buf_size, const char *filename) return 0; } +/* + * Writes the header to the specified offset. + * + * This will optionally read in buffer data from disk (otherwise zero-fill), + * and then update the header checksum. Header is converted to proper + * endianness before being written to the specified file offset + */ +static int vhdx_write_header(BlockDriverState *bs_file, VHDXHeader *hdr, + uint64_t offset, bool read) +{ + uint8_t *buffer = NULL; + int ret; + VHDXHeader header_le; + + assert(bs_file != NULL); + assert(hdr != NULL); + + /* the header checksum is not over just the packed size of VHDXHeader, + * but rather over the entire 'reserved' range for the header, which is + * 4KB (VHDX_HEADER_SIZE). */ + + buffer = qemu_blockalign(bs_file, VHDX_HEADER_SIZE); + if (read) { + /* if true, we can't assume the extra reserved bytes are 0 */ + ret = bdrv_pread(bs_file, offset, buffer, VHDX_HEADER_SIZE); + if (ret < 0) { + goto exit; + } + } else { + memset(buffer, 0, VHDX_HEADER_SIZE); + } + + /* overwrite the actual VHDXHeader portion */ + memcpy(buffer, hdr, sizeof(VHDXHeader)); + hdr->checksum = vhdx_update_checksum(buffer, VHDX_HEADER_SIZE, + offsetof(VHDXHeader, checksum)); + vhdx_header_le_export(hdr, &header_le); + ret = bdrv_pwrite_sync(bs_file, offset, &header_le, sizeof(VHDXHeader)); + +exit: + qemu_vfree(buffer); + return ret; +} + /* Update the VHDX headers * * This follows the VHDX spec procedures for header updates. @@ -282,8 +334,6 @@ static int vhdx_update_header(BlockDriverState *bs, BDRVVHDXState *s, VHDXHeader *active_header; VHDXHeader *inactive_header; - VHDXHeader header_le; - uint8_t *buffer; /* operate on the non-current header */ if (s->curr_header == 0) { @@ -311,31 +361,13 @@ static int vhdx_update_header(BlockDriverState *bs, BDRVVHDXState *s, inactive_header->log_guid = *log_guid; } - /* the header checksum is not over just the packed size of VHDXHeader, - * but rather over the entire 'reserved' range for the header, which is - * 4KB (VHDX_HEADER_SIZE). */ - - buffer = qemu_blockalign(bs, VHDX_HEADER_SIZE); - /* we can't assume the extra reserved bytes are 0 */ - ret = bdrv_pread(bs->file, header_offset, buffer, VHDX_HEADER_SIZE); - if (ret < 0) { - goto exit; - } - /* overwrite the actual VHDXHeader portion */ - memcpy(buffer, inactive_header, sizeof(VHDXHeader)); - inactive_header->checksum = - vhdx_update_checksum(buffer, VHDX_HEADER_SIZE, - offsetof(VHDXHeader, checksum)); - vhdx_header_le_export(inactive_header, &header_le); - ret = bdrv_pwrite_sync(bs->file, header_offset, &header_le, - sizeof(VHDXHeader)); + vhdx_write_header(bs->file, inactive_header, header_offset, true); if (ret < 0) { goto exit; } s->curr_header = hdr_idx; exit: - qemu_vfree(buffer); return ret; } @@ -773,10 +805,7 @@ static int vhdx_parse_metadata(BlockDriverState *bs, BDRVVHDXState *s) goto exit; } - s->logical_sector_size_bits = 31 - clz32(s->logical_sector_size); - s->sectors_per_block_bits = 31 - clz32(s->sectors_per_block); - s->chunk_ratio_bits = 63 - clz64(s->chunk_ratio); - s->block_size_bits = 31 - clz32(s->block_size); + vhdx_set_shift_bits(s); ret = 0; @@ -785,6 +814,31 @@ exit: return ret; } +/* + * Calculate the number of BAT entries, including sector + * bitmap entries. + */ +static void vhdx_calc_bat_entries(BDRVVHDXState *s) +{ + uint32_t data_blocks_cnt, bitmap_blocks_cnt; + + data_blocks_cnt = s->virtual_disk_size >> s->block_size_bits; + if (s->virtual_disk_size - (data_blocks_cnt << s->block_size_bits)) { + data_blocks_cnt++; + } + bitmap_blocks_cnt = data_blocks_cnt >> s->chunk_ratio_bits; + if (data_blocks_cnt - (bitmap_blocks_cnt << s->chunk_ratio_bits)) { + bitmap_blocks_cnt++; + } + + if (s->parent_entries) { + s->bat_entries = bitmap_blocks_cnt * (s->chunk_ratio + 1); + } else { + s->bat_entries = data_blocks_cnt + + ((data_blocks_cnt - 1) >> s->chunk_ratio_bits); + } + +} static void vhdx_close(BlockDriverState *bs) { @@ -811,7 +865,6 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags, int ret = 0; uint32_t i; uint64_t signature; - uint32_t data_blocks_cnt, bitmap_blocks_cnt; bool log_flushed = false; @@ -862,21 +915,7 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags, * logical_sector_size */ bs->total_sectors = s->virtual_disk_size >> s->logical_sector_size_bits; - data_blocks_cnt = s->virtual_disk_size >> s->block_size_bits; - if (s->virtual_disk_size - (data_blocks_cnt << s->block_size_bits)) { - data_blocks_cnt++; - } - bitmap_blocks_cnt = data_blocks_cnt >> s->chunk_ratio_bits; - if (data_blocks_cnt - (bitmap_blocks_cnt << s->chunk_ratio_bits)) { - bitmap_blocks_cnt++; - } - - if (s->parent_entries) { - s->bat_entries = bitmap_blocks_cnt * (s->chunk_ratio + 1); - } else { - s->bat_entries = data_blocks_cnt + - ((data_blocks_cnt - 1) >> s->chunk_ratio_bits); - } + vhdx_calc_bat_entries(s); s->bat_offset = s->bat_rt.file_offset; |
