| /* |
| * Block driver for Hyper-V VHDX Images |
| * |
| * Copyright (c) 2013 Red Hat, Inc., |
| * |
| * Authors: |
| * Jeff Cody <jcody@redhat.com> |
| * |
| * This is based on the "VHDX Format Specification v1.00", published 8/25/2012 |
| * by Microsoft: |
| * https://www.microsoft.com/en-us/download/details.aspx?id=34750 |
| * |
| * This file covers the functionality of the metadata log writing, parsing, and |
| * replay. |
| * |
| * This work is licensed under the terms of the GNU LGPL, version 2 or later. |
| * See the COPYING.LIB file in the top-level directory. |
| * |
| */ |
| |
| #include "qemu/osdep.h" |
| #include "qapi/error.h" |
| #include "block/block-io.h" |
| #include "block/block_int.h" |
| #include "qemu/error-report.h" |
| #include "qemu/bswap.h" |
| #include "qemu/memalign.h" |
| #include "vhdx.h" |
| |
| |
| typedef struct VHDXLogSequence { |
| bool valid; |
| uint32_t count; |
| VHDXLogEntries log; |
| VHDXLogEntryHeader hdr; |
| } VHDXLogSequence; |
| |
| typedef struct VHDXLogDescEntries { |
| VHDXLogEntryHeader hdr; |
| VHDXLogDescriptor desc[]; |
| } VHDXLogDescEntries; |
| |
| static const MSGUID zero_guid = { 0 }; |
| |
| /* The log located on the disk is circular buffer containing |
| * sectors of 4096 bytes each. |
| * |
| * It is assumed for the read/write functions below that the |
| * circular buffer scheme uses a 'one sector open' to indicate |
| * the buffer is full. Given the validation methods used for each |
| * sector, this method should be compatible with other methods that |
| * do not waste a sector. |
| */ |
| |
| |
| /* Allow peeking at the hdr entry at the beginning of the current |
| * read index, without advancing the read index */ |
| static int GRAPH_RDLOCK |
| vhdx_log_peek_hdr(BlockDriverState *bs, VHDXLogEntries *log, |
| VHDXLogEntryHeader *hdr) |
| { |
| int ret = 0; |
| uint64_t offset; |
| uint32_t read; |
| |
| assert(hdr != NULL); |
| |
| /* peek is only supported on sector boundaries */ |
| if (log->read % VHDX_LOG_SECTOR_SIZE) { |
| ret = -EFAULT; |
| goto exit; |
| } |
| |
| read = log->read; |
| /* we are guaranteed that a) log sectors are 4096 bytes, |
| * and b) the log length is a multiple of 1MB. So, there |
| * is always a round number of sectors in the buffer */ |
| if ((read + sizeof(VHDXLogEntryHeader)) > log->length) { |
| read = 0; |
| } |
| |
| if (read == log->write) { |
| ret = -EINVAL; |
| goto exit; |
| } |
| |
| offset = log->offset + read; |
| |
| ret = bdrv_pread(bs->file, offset, sizeof(VHDXLogEntryHeader), hdr, 0); |
| if (ret < 0) { |
| goto exit; |
| } |
| vhdx_log_entry_hdr_le_import(hdr); |
| |
| exit: |
| return ret; |
| } |
| |
| /* Index increment for log, based on sector boundaries */ |
| static int vhdx_log_inc_idx(uint32_t idx, uint64_t length) |
| { |
| idx += VHDX_LOG_SECTOR_SIZE; |
| /* we are guaranteed that a) log sectors are 4096 bytes, |
| * and b) the log length is a multiple of 1MB. So, there |
| * is always a round number of sectors in the buffer */ |
| return idx >= length ? 0 : idx; |
| } |
| |
| |
| /* Reset the log to empty */ |
| static void GRAPH_RDLOCK vhdx_log_reset(BlockDriverState *bs, BDRVVHDXState *s) |
| { |
| MSGUID guid = { 0 }; |
| s->log.read = s->log.write = 0; |
| /* a log guid of 0 indicates an empty log to any parser of v0 |
| * VHDX logs */ |
| vhdx_update_headers(bs, s, false, &guid); |
| } |
| |
| /* Reads num_sectors from the log (all log sectors are 4096 bytes), |
| * into buffer 'buffer'. Upon return, *sectors_read will contain |
| * the number of sectors successfully read. |
| * |
| * It is assumed that 'buffer' is already allocated, and of sufficient |
| * size (i.e. >= 4096*num_sectors). |
| * |
| * If 'peek' is true, then the tail (read) pointer for the circular buffer is |
| * not modified. |
| * |
| * 0 is returned on success, -errno otherwise. */ |
| static int GRAPH_RDLOCK |
| vhdx_log_read_sectors(BlockDriverState *bs, VHDXLogEntries *log, |
| uint32_t *sectors_read, void *buffer, |
| uint32_t num_sectors, bool peek) |
| { |
| int ret = 0; |
| uint64_t offset; |
| uint32_t read; |
| |
| read = log->read; |
| |
| *sectors_read = 0; |
| while (num_sectors) { |
| if (read == log->write) { |
| /* empty */ |
| break; |
| } |
| offset = log->offset + read; |
| |
| ret = bdrv_pread(bs->file, offset, VHDX_LOG_SECTOR_SIZE, buffer, 0); |
| if (ret < 0) { |
| goto exit; |
| } |
| read = vhdx_log_inc_idx(read, log->length); |
| |
| *sectors_read = *sectors_read + 1; |
| num_sectors--; |
| } |
| |
| exit: |
| if (!peek) { |
| log->read = read; |
| } |
| return ret; |
| } |
| |
| /* Writes num_sectors to the log (all log sectors are 4096 bytes), |
| * from buffer 'buffer'. Upon return, *sectors_written will contain |
| * the number of sectors successfully written. |
| * |
| * It is assumed that 'buffer' is at least 4096*num_sectors large. |
| * |
| * 0 is returned on success, -errno otherwise */ |
| static int coroutine_fn GRAPH_RDLOCK |
| vhdx_log_write_sectors(BlockDriverState *bs, VHDXLogEntries *log, |
| uint32_t *sectors_written, void *buffer, |
| uint32_t num_sectors) |
| { |
| int ret = 0; |
| uint64_t offset; |
| uint32_t write; |
| void *buffer_tmp; |
| BDRVVHDXState *s = bs->opaque; |
| |
| ret = vhdx_user_visible_write(bs, s); |
| if (ret < 0) { |
| goto exit; |
| } |
| |
| write = log->write; |
| |
| buffer_tmp = buffer; |
| while (num_sectors) { |
| |
| offset = log->offset + write; |
| write = vhdx_log_inc_idx(write, log->length); |
| if (write == log->read) { |
| /* full */ |
| break; |
| } |
| ret = bdrv_co_pwrite(bs->file, offset, VHDX_LOG_SECTOR_SIZE, buffer_tmp, 0); |
| if (ret < 0) { |
| goto exit; |
| } |
| buffer_tmp += VHDX_LOG_SECTOR_SIZE; |
| |
| log->write = write; |
| *sectors_written = *sectors_written + 1; |
| num_sectors--; |
| } |
| |
| exit: |
| return ret; |
| } |
| |
| |
| /* Validates a log entry header */ |
| static bool vhdx_log_hdr_is_valid(VHDXLogEntries *log, VHDXLogEntryHeader *hdr, |
| BDRVVHDXState *s) |
| { |
| int valid = false; |
| |
| if (hdr->signature != VHDX_LOG_SIGNATURE) { |
| goto exit; |
| } |
| |
| /* if the individual entry length is larger than the whole log |
| * buffer, that is obviously invalid */ |
| if (log->length < hdr->entry_length) { |
| goto exit; |
| } |
| |
| /* length of entire entry must be in units of 4KB (log sector size) */ |
| if (hdr->entry_length % (VHDX_LOG_SECTOR_SIZE)) { |
| goto exit; |
| } |
| |
| /* per spec, sequence # must be > 0 */ |
| if (hdr->sequence_number == 0) { |
| goto exit; |
| } |
| |
| /* log entries are only valid if they match the file-wide log guid |
| * found in the active header */ |
| if (!guid_eq(hdr->log_guid, s->headers[s->curr_header]->log_guid)) { |
| goto exit; |
| } |
| |
| if (hdr->descriptor_count * sizeof(VHDXLogDescriptor) > hdr->entry_length) { |
| goto exit; |
| } |
| |
| valid = true; |
| |
| exit: |
| return valid; |
| } |
| |
| /* |
| * Given a log header, this will validate that the descriptors and the |
| * corresponding data sectors (if applicable) |
| * |
| * Validation consists of: |
| * 1. Making sure the sequence numbers matches the entry header |
| * 2. Verifying a valid signature ('zero' or 'desc' for descriptors) |
| * 3. File offset field is a multiple of 4KB |
| * 4. If a data descriptor, the corresponding data sector |
| * has its signature ('data') and matching sequence number |
| * |
| * @desc: the data buffer containing the descriptor |
| * @hdr: the log entry header |
| * |
| * Returns true if valid |
| */ |
| static bool vhdx_log_desc_is_valid(VHDXLogDescriptor *desc, |
| VHDXLogEntryHeader *hdr) |
| { |
| bool ret = false; |
| |
| if (desc->sequence_number != hdr->sequence_number) { |
| goto exit; |
| } |
| if (desc->file_offset % VHDX_LOG_SECTOR_SIZE) { |
| goto exit; |
| } |
| |
| if (desc->signature == VHDX_LOG_ZERO_SIGNATURE) { |
| if (desc->zero_length % VHDX_LOG_SECTOR_SIZE == 0) { |
| /* valid */ |
| ret = true; |
| } |
| } else if (desc->signature == VHDX_LOG_DESC_SIGNATURE) { |
| /* valid */ |
| ret = true; |
| } |
| |
| exit: |
| return ret; |
| } |
| |
| |
| /* Prior to sector data for a log entry, there is the header |
| * and the descriptors referenced in the header: |
| * |
| * [] = 4KB sector |
| * |
| * [ hdr, desc ][ desc ][ ... ][ data ][ ... ] |
| * |
| * The first sector in a log entry has a 64 byte header, and |
| * up to 126 32-byte descriptors. If more descriptors than |
| * 126 are required, then subsequent sectors can have up to 128 |
| * descriptors. Each sector is 4KB. Data follows the descriptor |
| * sectors. |
| * |
| * This will return the number of sectors needed to encompass |
| * the passed number of descriptors in desc_cnt. |
| * |
| * This will never return 0, even if desc_cnt is 0. |
| */ |
| static int vhdx_compute_desc_sectors(uint32_t desc_cnt) |
| { |
| uint32_t desc_sectors; |
| |
| desc_cnt += 2; /* account for header in first sector */ |
| desc_sectors = desc_cnt / 128; |
| if (desc_cnt % 128) { |
| desc_sectors++; |
| } |
| |
| return desc_sectors; |
| } |
| |
| |
| /* Reads the log header, and subsequent descriptors (if any). This |
| * will allocate all the space for buffer, which must be NULL when |
| * passed into this function. Each descriptor will also be validated, |
| * and error returned if any are invalid. */ |
| static int GRAPH_RDLOCK |
| vhdx_log_read_desc(BlockDriverState *bs, BDRVVHDXState *s, VHDXLogEntries *log, |
| VHDXLogDescEntries **buffer, bool convert_endian) |
| { |
| int ret = 0; |
| uint32_t desc_sectors; |
| uint32_t sectors_read; |
| VHDXLogEntryHeader hdr; |
| VHDXLogDescEntries *desc_entries = NULL; |
| VHDXLogDescriptor desc; |
| int i; |
| |
| assert(*buffer == NULL); |
| |
| ret = vhdx_log_peek_hdr(bs, log, &hdr); |
| if (ret < 0) { |
| goto exit; |
| } |
| |
| if (vhdx_log_hdr_is_valid(log, &hdr, s) == false) { |
| ret = -EINVAL; |
| goto exit; |
| } |
| |
| desc_sectors = vhdx_compute_desc_sectors(hdr.descriptor_count); |
| desc_entries = qemu_try_blockalign(bs->file->bs, |
| desc_sectors * VHDX_LOG_SECTOR_SIZE); |
| if (desc_entries == NULL) { |
| ret = -ENOMEM; |
| goto exit; |
| } |
| |
| ret = vhdx_log_read_sectors(bs, log, §ors_read, desc_entries, |
| desc_sectors, false); |
| if (ret < 0) { |
| goto free_and_exit; |
| } |
| if (sectors_read != desc_sectors) { |
| ret = -EINVAL; |
| goto free_and_exit; |
| } |
| |
| /* put in proper endianness, and validate each desc */ |
| for (i = 0; i < hdr.descriptor_count; i++) { |
| desc = desc_entries->desc[i]; |
| vhdx_log_desc_le_import(&desc); |
| if (convert_endian) { |
| desc_entries->desc[i] = desc; |
| } |
| if (vhdx_log_desc_is_valid(&desc, &hdr) == false) { |
| ret = -EINVAL; |
| goto free_and_exit; |
| } |
| } |
| if (convert_endian) { |
| desc_entries->hdr = hdr; |
| } |
| |
| *buffer = desc_entries; |
| goto exit; |
| |
| free_and_exit: |
| qemu_vfree(desc_entries); |
| exit: |
| return ret; |
| } |
| |
| |
| /* Flushes the descriptor described by desc to the VHDX image file. |
| * If the descriptor is a data descriptor, than 'data' must be non-NULL, |
| * and >= 4096 bytes (VHDX_LOG_SECTOR_SIZE), containing the data to be |
| * written. |
| * |
| * Verification is performed to make sure the sequence numbers of a data |
| * descriptor match the sequence number in the desc. |
| * |
| * For a zero descriptor, it may describe multiple sectors to fill with zeroes. |
| * In this case, it should be noted that zeroes are written to disk, and the |
| * image file is not extended as a sparse file. */ |
| static int GRAPH_RDLOCK |
| vhdx_log_flush_desc(BlockDriverState *bs, VHDXLogDescriptor *desc, |
| VHDXLogDataSector *data) |
| { |
| int ret = 0; |
| uint64_t seq, file_offset; |
| uint32_t offset = 0; |
| void *buffer = NULL; |
| uint64_t count = 1; |
| int i; |
| |
| buffer = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE); |
| |
| if (desc->signature == VHDX_LOG_DESC_SIGNATURE) { |
| /* data sector */ |
| if (data == NULL) { |
| ret = -EFAULT; |
| goto exit; |
| } |
| |
| /* The sequence number of the data sector must match that |
| * in the descriptor */ |
| seq = data->sequence_high; |
| seq <<= 32; |
| seq |= data->sequence_low & 0xffffffff; |
| |
| if (seq != desc->sequence_number) { |
| ret = -EINVAL; |
| goto exit; |
| } |
| |
| /* Each data sector is in total 4096 bytes, however the first |
| * 8 bytes, and last 4 bytes, are located in the descriptor */ |
| memcpy(buffer, &desc->leading_bytes, 8); |
| offset += 8; |
| |
| memcpy(buffer+offset, data->data, 4084); |
| offset += 4084; |
| |
| memcpy(buffer+offset, &desc->trailing_bytes, 4); |
| |
| } else if (desc->signature == VHDX_LOG_ZERO_SIGNATURE) { |
| /* write 'count' sectors of sector */ |
| memset(buffer, 0, VHDX_LOG_SECTOR_SIZE); |
| count = desc->zero_length / VHDX_LOG_SECTOR_SIZE; |
| } else { |
| error_report("Invalid VHDX log descriptor entry signature 0x%" PRIx32, |
| desc->signature); |
| ret = -EINVAL; |
| goto exit; |
| } |
| |
| file_offset = desc->file_offset; |
| |
| /* count is only > 1 if we are writing zeroes */ |
| for (i = 0; i < count; i++) { |
| ret = bdrv_pwrite_sync(bs->file, file_offset, VHDX_LOG_SECTOR_SIZE, |
| buffer, 0); |
| if (ret < 0) { |
| goto exit; |
| } |
| file_offset += VHDX_LOG_SECTOR_SIZE; |
| } |
| |
| exit: |
| qemu_vfree(buffer); |
| return ret; |
| } |
| |
| /* Flush the entire log (as described by 'logs') to the VHDX image |
| * file, and then set the log to 'empty' status once complete. |
| * |
| * The log entries should be validate prior to flushing */ |
| static int GRAPH_RDLOCK |
| vhdx_log_flush(BlockDriverState *bs, BDRVVHDXState *s, VHDXLogSequence *logs) |
| { |
| int ret = 0; |
| int i; |
| uint32_t cnt, sectors_read; |
| uint64_t new_file_size; |
| void *data = NULL; |
| int64_t file_length; |
| VHDXLogDescEntries *desc_entries = NULL; |
| VHDXLogEntryHeader hdr_tmp = { 0 }; |
| |
| cnt = logs->count; |
| |
| data = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE); |
| |
| ret = vhdx_user_visible_write(bs, s); |
| if (ret < 0) { |
| goto exit; |
| } |
| |
| /* each iteration represents one log sequence, which may span multiple |
| * sectors */ |
| while (cnt--) { |
| ret = vhdx_log_peek_hdr(bs, &logs->log, &hdr_tmp); |
| if (ret < 0) { |
| goto exit; |
| } |
| file_length = bdrv_getlength(bs->file->bs); |
| if (file_length < 0) { |
| ret = file_length; |
| goto exit; |
| } |
| /* if the log shows a FlushedFileOffset larger than our current file |
| * size, then that means the file has been truncated / corrupted, and |
| * we must refused to open it / use it */ |
| if (hdr_tmp.flushed_file_offset > file_length) { |
| ret = -EINVAL; |
| goto exit; |
| } |
| |
| ret = vhdx_log_read_desc(bs, s, &logs->log, &desc_entries, true); |
| if (ret < 0) { |
| goto exit; |
| } |
| |
| for (i = 0; i < desc_entries->hdr.descriptor_count; i++) { |
| if (desc_entries->desc[i].signature == VHDX_LOG_DESC_SIGNATURE) { |
| /* data sector, so read a sector to flush */ |
| ret = vhdx_log_read_sectors(bs, &logs->log, §ors_read, |
| data, 1, false); |
| if (ret < 0) { |
| goto exit; |
| } |
| if (sectors_read != 1) { |
| ret = -EINVAL; |
| goto exit; |
| } |
| vhdx_log_data_le_import(data); |
| } |
| |
| ret = vhdx_log_flush_desc(bs, &desc_entries->desc[i], data); |
| if (ret < 0) { |
| goto exit; |
| } |
| } |
| if (file_length < desc_entries->hdr.last_file_offset) { |
| new_file_size = desc_entries->hdr.last_file_offset; |
| if (new_file_size % (1 * MiB)) { |
| /* round up to nearest 1MB boundary */ |
| new_file_size = QEMU_ALIGN_UP(new_file_size, MiB); |
| if (new_file_size > INT64_MAX) { |
| ret = -EINVAL; |
| goto exit; |
| } |
| ret = bdrv_truncate(bs->file, new_file_size, false, |
| PREALLOC_MODE_OFF, 0, NULL); |
| if (ret < 0) { |
| goto exit; |
| } |
| } |
| } |
| qemu_vfree(desc_entries); |
| desc_entries = NULL; |
| } |
| |
| ret = bdrv_flush(bs); |
| if (ret < 0) { |
| goto exit; |
| } |
| /* once the log is fully flushed, indicate that we have an empty log |
| * now. This also sets the log guid to 0, to indicate an empty log */ |
| vhdx_log_reset(bs, s); |
| |
| exit: |
| qemu_vfree(data); |
| qemu_vfree(desc_entries); |
| return ret; |
| } |
| |
| static int GRAPH_RDLOCK |
| vhdx_validate_log_entry(BlockDriverState *bs, BDRVVHDXState *s, |
| VHDXLogEntries *log, uint64_t seq, |
| bool *valid, VHDXLogEntryHeader *entry) |
| { |
| int ret = 0; |
| VHDXLogEntryHeader hdr; |
| void *buffer = NULL; |
| uint32_t i, desc_sectors, total_sectors, crc; |
| uint32_t sectors_read = 0; |
| VHDXLogDescEntries *desc_buffer = NULL; |
| |
| *valid = false; |
| |
| ret = vhdx_log_peek_hdr(bs, log, &hdr); |
| if (ret < 0) { |
| goto inc_and_exit; |
| } |
| |
| if (vhdx_log_hdr_is_valid(log, &hdr, s) == false) { |
| goto inc_and_exit; |
| } |
| |
| if (seq > 0) { |
| if (hdr.sequence_number != seq + 1) { |
| goto inc_and_exit; |
| } |
| } |
| |
| desc_sectors = vhdx_compute_desc_sectors(hdr.descriptor_count); |
| |
| /* Read all log sectors, and calculate log checksum */ |
| |
| total_sectors = hdr.entry_length / VHDX_LOG_SECTOR_SIZE; |
| |
| |
| /* read_desc() will increment the read idx */ |
| ret = vhdx_log_read_desc(bs, s, log, &desc_buffer, false); |
| if (ret < 0) { |
| goto free_and_exit; |
| } |
| |
| crc = vhdx_checksum_calc(0xffffffff, (void *)desc_buffer, |
| desc_sectors * VHDX_LOG_SECTOR_SIZE, 4); |
| crc ^= 0xffffffff; |
| |
| buffer = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE); |
| if (total_sectors > desc_sectors) { |
| for (i = 0; i < total_sectors - desc_sectors; i++) { |
| sectors_read = 0; |
| ret = vhdx_log_read_sectors(bs, log, §ors_read, buffer, |
| 1, false); |
| if (ret < 0 || sectors_read != 1) { |
| goto free_and_exit; |
| } |
| crc = vhdx_checksum_calc(crc, buffer, VHDX_LOG_SECTOR_SIZE, -1); |
| crc ^= 0xffffffff; |
| } |
| } |
| crc ^= 0xffffffff; |
| if (crc != hdr.checksum) { |
| goto free_and_exit; |
| } |
| |
| *valid = true; |
| *entry = hdr; |
| goto free_and_exit; |
| |
| inc_and_exit: |
| log->read = vhdx_log_inc_idx(log->read, log->length); |
| |
| free_and_exit: |
| qemu_vfree(buffer); |
| qemu_vfree(desc_buffer); |
| return ret; |
| } |
| |
| /* Search through the log circular buffer, and find the valid, active |
| * log sequence, if any exists |
| * */ |
| static int GRAPH_RDLOCK |
| vhdx_log_search(BlockDriverState *bs, BDRVVHDXState *s, VHDXLogSequence *logs) |
| { |
| int ret = 0; |
| uint32_t tail; |
| bool seq_valid = false; |
| VHDXLogSequence candidate = { 0 }; |
| VHDXLogEntryHeader hdr = { 0 }; |
| VHDXLogEntries curr_log; |
| |
| memcpy(&curr_log, &s->log, sizeof(VHDXLogEntries)); |
| curr_log.write = curr_log.length; /* assume log is full */ |
| curr_log.read = 0; |
| |
| |
| /* now we will go through the whole log sector by sector, until |
| * we find a valid, active log sequence, or reach the end of the |
| * log buffer */ |
| for (;;) { |
| uint64_t curr_seq = 0; |
| VHDXLogSequence current = { 0 }; |
| |
| tail = curr_log.read; |
| |
| ret = vhdx_validate_log_entry(bs, s, &curr_log, curr_seq, |
| &seq_valid, &hdr); |
| if (ret < 0) { |
| goto exit; |
| } |
| |
| if (seq_valid) { |
| current.valid = true; |
| current.log = curr_log; |
| current.log.read = tail; |
| current.log.write = curr_log.read; |
| current.count = 1; |
| current.hdr = hdr; |
| |
| |
| for (;;) { |
| ret = vhdx_validate_log_entry(bs, s, &curr_log, curr_seq, |
| &seq_valid, &hdr); |
| if (ret < 0) { |
| goto exit; |
| } |
| if (seq_valid == false) { |
| break; |
| } |
| current.log.write = curr_log.read; |
| current.count++; |
| |
| curr_seq = hdr.sequence_number; |
| } |
| } |
| |
| if (current.valid) { |
| if (candidate.valid == false || |
| current.hdr.sequence_number > candidate.hdr.sequence_number) { |
| candidate = current; |
| } |
| } |
| |
| if (curr_log.read < tail) { |
| break; |
| } |
| } |
| |
| *logs = candidate; |
| |
| if (candidate.valid) { |
| /* this is the next sequence number, for writes */ |
| s->log.sequence = candidate.hdr.sequence_number + 1; |
| } |
| |
| |
| exit: |
| return ret; |
| } |
| |
| /* Parse the replay log. Per the VHDX spec, if the log is present |
| * it must be replayed prior to opening the file, even read-only. |
| * |
| * If read-only, we must replay the log in RAM (or refuse to open |
| * a dirty VHDX file read-only) */ |
| int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s, bool *flushed, |
| Error **errp) |
| { |
| int ret = 0; |
| VHDXHeader *hdr; |
| VHDXLogSequence logs = { 0 }; |
| |
| hdr = s->headers[s->curr_header]; |
| |
| *flushed = false; |
| |
| /* s->log.hdr is freed in vhdx_close() */ |
| if (s->log.hdr == NULL) { |
| s->log.hdr = qemu_blockalign(bs, sizeof(VHDXLogEntryHeader)); |
| } |
| |
| s->log.offset = hdr->log_offset; |
| s->log.length = hdr->log_length; |
| |
| if (s->log.offset < VHDX_LOG_MIN_SIZE || |
| s->log.offset % VHDX_LOG_MIN_SIZE) { |
| ret = -EINVAL; |
| goto exit; |
| } |
| |
| /* per spec, only log version of 0 is supported */ |
| if (hdr->log_version != 0) { |
| ret = -EINVAL; |
| goto exit; |
| } |
| |
| /* If either the log guid, or log length is zero, |
| * then a replay log is not present */ |
| if (guid_eq(hdr->log_guid, zero_guid)) { |
| goto exit; |
| } |
| |
| if (hdr->log_length == 0) { |
| goto exit; |
| } |
| |
| if (hdr->log_length % VHDX_LOG_MIN_SIZE) { |
| ret = -EINVAL; |
| goto exit; |
| } |
| |
| |
| /* The log is present, we need to find if and where there is an active |
| * sequence of valid entries present in the log. */ |
| |
| ret = vhdx_log_search(bs, s, &logs); |
| if (ret < 0) { |
| goto exit; |
| } |
| |
| if (logs.valid) { |
| if (bdrv_is_read_only(bs)) { |
| bdrv_refresh_filename(bs); |
| ret = -EPERM; |
| error_setg(errp, |
| "VHDX image file '%s' opened read-only, but " |
| "contains a log that needs to be replayed", |
| bs->filename); |
| error_append_hint(errp, "To replay the log, run:\n" |
| "qemu-img check -r all '%s'\n", |
| bs->filename); |
| goto exit; |
| } |
| /* now flush the log */ |
| ret = vhdx_log_flush(bs, s, &logs); |
| if (ret < 0) { |
| goto exit; |
| } |
| *flushed = true; |
| } |
| |
| |
| exit: |
| return ret; |
| } |
| |
| |
| |
| static void vhdx_log_raw_to_le_sector(VHDXLogDescriptor *desc, |
| VHDXLogDataSector *sector, void *data, |
| uint64_t seq) |
| { |
| /* 8 + 4084 + 4 = 4096, 1 log sector */ |
| memcpy(&desc->leading_bytes, data, 8); |
| data += 8; |
| desc->leading_bytes = cpu_to_le64(desc->leading_bytes); |
| memcpy(sector->data, data, 4084); |
| data += 4084; |
| memcpy(&desc->trailing_bytes, data, 4); |
| desc->trailing_bytes = cpu_to_le32(desc->trailing_bytes); |
| data += 4; |
| |
| sector->sequence_high = (uint32_t) (seq >> 32); |
| sector->sequence_low = (uint32_t) (seq & 0xffffffff); |
| sector->data_signature = VHDX_LOG_DATA_SIGNATURE; |
| |
| vhdx_log_desc_le_export(desc); |
| vhdx_log_data_le_export(sector); |
| } |
| |
| |
| static int coroutine_fn GRAPH_RDLOCK |
| vhdx_log_write(BlockDriverState *bs, BDRVVHDXState *s, |
| void *data, uint32_t length, uint64_t offset) |
| { |
| int ret = 0; |
| void *buffer = NULL; |
| void *merged_sector = NULL; |
| void *data_tmp, *sector_write; |
| unsigned int i; |
| int sector_offset; |
| uint32_t desc_sectors, sectors, total_length; |
| uint32_t sectors_written = 0; |
| uint32_t aligned_length; |
| uint32_t leading_length = 0; |
| uint32_t trailing_length = 0; |
| uint32_t partial_sectors = 0; |
| uint32_t bytes_written = 0; |
| uint64_t file_offset; |
| int64_t file_length; |
| VHDXHeader *header; |
| VHDXLogEntryHeader new_hdr; |
| VHDXLogDescriptor *new_desc = NULL; |
| VHDXLogDataSector *data_sector = NULL; |
| MSGUID new_guid = { 0 }; |
| |
| header = s->headers[s->curr_header]; |
| |
| /* need to have offset read data, and be on 4096 byte boundary */ |
| |
| if (length > header->log_length) { |
| /* no log present. we could create a log here instead of failing */ |
| ret = -EINVAL; |
| goto exit; |
| } |
| |
| if (guid_eq(header->log_guid, zero_guid)) { |
| vhdx_guid_generate(&new_guid); |
| vhdx_update_headers(bs, s, false, &new_guid); |
| } else { |
| /* currently, we require that the log be flushed after |
| * every write. */ |
| ret = -ENOTSUP; |
| goto exit; |
| } |
| |
| /* 0 is an invalid sequence number, but may also represent the first |
| * log write (or a wrapped seq) */ |
| if (s->log.sequence == 0) { |
| s->log.sequence = 1; |
| } |
| |
| sector_offset = offset % VHDX_LOG_SECTOR_SIZE; |
| file_offset = QEMU_ALIGN_DOWN(offset, VHDX_LOG_SECTOR_SIZE); |
| |
| aligned_length = length; |
| |
| /* add in the unaligned head and tail bytes */ |
| if (sector_offset) { |
| leading_length = (VHDX_LOG_SECTOR_SIZE - sector_offset); |
| leading_length = leading_length > length ? length : leading_length; |
| aligned_length -= leading_length; |
| partial_sectors++; |
| } |
| |
| sectors = aligned_length / VHDX_LOG_SECTOR_SIZE; |
| trailing_length = aligned_length - (sectors * VHDX_LOG_SECTOR_SIZE); |
| if (trailing_length) { |
| partial_sectors++; |
| } |
| |
| sectors += partial_sectors; |
| |
| file_length = bdrv_co_getlength(bs->file->bs); |
| if (file_length < 0) { |
| ret = file_length; |
| goto exit; |
| } |
| |
| /* sectors is now how many sectors the data itself takes, not |
| * including the header and descriptor metadata */ |
| |
| new_hdr = (VHDXLogEntryHeader) { |
| .signature = VHDX_LOG_SIGNATURE, |
| .tail = s->log.tail, |
| .sequence_number = s->log.sequence, |
| .descriptor_count = sectors, |
| .reserved = 0, |
| .flushed_file_offset = file_length, |
| .last_file_offset = file_length, |
| .log_guid = header->log_guid, |
| }; |
| |
| |
| desc_sectors = vhdx_compute_desc_sectors(new_hdr.descriptor_count); |
| |
| total_length = (desc_sectors + sectors) * VHDX_LOG_SECTOR_SIZE; |
| new_hdr.entry_length = total_length; |
| |
| vhdx_log_entry_hdr_le_export(&new_hdr); |
| |
| buffer = qemu_blockalign(bs, total_length); |
| memcpy(buffer, &new_hdr, sizeof(new_hdr)); |
| |
| new_desc = buffer + sizeof(new_hdr); |
| data_sector = buffer + (desc_sectors * VHDX_LOG_SECTOR_SIZE); |
| data_tmp = data; |
| |
| /* All log sectors are 4KB, so for any partial sectors we must |
| * merge the data with preexisting data from the final file |
| * destination */ |
| merged_sector = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE); |
| |
| for (i = 0; i < sectors; i++) { |
| new_desc->signature = VHDX_LOG_DESC_SIGNATURE; |
| new_desc->sequence_number = s->log.sequence; |
| new_desc->file_offset = file_offset; |
| |
| if (i == 0 && leading_length) { |
| /* partial sector at the front of the buffer */ |
| ret = bdrv_co_pread(bs->file, file_offset, VHDX_LOG_SECTOR_SIZE, |
| merged_sector, 0); |
| if (ret < 0) { |
| goto exit; |
| } |
| memcpy(merged_sector + sector_offset, data_tmp, leading_length); |
| bytes_written = leading_length; |
| sector_write = merged_sector; |
| } else if (i == sectors - 1 && trailing_length) { |
| /* partial sector at the end of the buffer */ |
| ret = bdrv_co_pread(bs->file, file_offset + trailing_length, |
| VHDX_LOG_SECTOR_SIZE - trailing_length, |
| merged_sector + trailing_length, 0); |
| if (ret < 0) { |
| goto exit; |
| } |
| memcpy(merged_sector, data_tmp, trailing_length); |
| bytes_written = trailing_length; |
| sector_write = merged_sector; |
| } else { |
| bytes_written = VHDX_LOG_SECTOR_SIZE; |
| sector_write = data_tmp; |
| } |
| |
| /* populate the raw sector data into the proper structures, |
| * as well as update the descriptor, and convert to proper |
| * endianness */ |
| vhdx_log_raw_to_le_sector(new_desc, data_sector, sector_write, |
| s->log.sequence); |
| |
| data_tmp += bytes_written; |
| data_sector++; |
| new_desc++; |
| file_offset += VHDX_LOG_SECTOR_SIZE; |
| } |
| |
| /* checksum covers entire entry, from the log header through the |
| * last data sector */ |
| vhdx_update_checksum(buffer, total_length, |
| offsetof(VHDXLogEntryHeader, checksum)); |
| |
| /* now write to the log */ |
| ret = vhdx_log_write_sectors(bs, &s->log, §ors_written, buffer, |
| desc_sectors + sectors); |
| if (ret < 0) { |
| goto exit; |
| } |
| |
| if (sectors_written != desc_sectors + sectors) { |
| /* instead of failing, we could flush the log here */ |
| ret = -EINVAL; |
| goto exit; |
| } |
| |
| s->log.sequence++; |
| /* write new tail */ |
| s->log.tail = s->log.write; |
| |
| exit: |
| qemu_vfree(buffer); |
| qemu_vfree(merged_sector); |
| return ret; |
| } |
| |
| /* Perform a log write, and then immediately flush the entire log */ |
| int coroutine_fn |
| vhdx_log_write_and_flush(BlockDriverState *bs, BDRVVHDXState *s, |
| void *data, uint32_t length, uint64_t offset) |
| { |
| int ret = 0; |
| VHDXLogSequence logs = { .valid = true, |
| .count = 1, |
| .hdr = { 0 } }; |
| |
| |
| /* Make sure data written (new and/or changed blocks) is stable |
| * on disk, before creating log entry */ |
| ret = bdrv_co_flush(bs); |
| if (ret < 0) { |
| goto exit; |
| } |
| |
| ret = vhdx_log_write(bs, s, data, length, offset); |
| if (ret < 0) { |
| goto exit; |
| } |
| logs.log = s->log; |
| |
| /* Make sure log is stable on disk */ |
| ret = bdrv_co_flush(bs); |
| if (ret < 0) { |
| goto exit; |
| } |
| |
| ret = vhdx_log_flush(bs, s, &logs); |
| if (ret < 0) { |
| goto exit; |
| } |
| |
| s->log = logs.log; |
| |
| exit: |
| return ret; |
| } |
| |
