diff options
Diffstat (limited to 'qemu/block/vhdx-log.c')
| -rw-r--r-- | qemu/block/vhdx-log.c | 1043 |
1 files changed, 0 insertions, 1043 deletions
diff --git a/qemu/block/vhdx-log.c b/qemu/block/vhdx-log.c deleted file mode 100644 index 7ea7187fc..000000000 --- a/qemu/block/vhdx-log.c +++ /dev/null @@ -1,1043 +0,0 @@ -/* - * 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 "qemu-common.h" -#include "block/block_int.h" -#include "qemu/error-report.h" -#include "qemu/module.h" -#include "block/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 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->bs, offset, hdr, sizeof(VHDXLogEntryHeader)); - 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 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 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->bs, offset, buffer, VHDX_LOG_SECTOR_SIZE); - 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 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_pwrite(bs->file->bs, offset, buffer_tmp, - VHDX_LOG_SECTOR_SIZE); - 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 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 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->bs, file_offset, buffer, - VHDX_LOG_SECTOR_SIZE); - 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 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; - 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; - } - /* 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 > bdrv_getlength(bs->file->bs)) { - 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 (bdrv_getlength(bs->file->bs) < desc_entries->hdr.last_file_offset) { - new_file_size = desc_entries->hdr.last_file_offset; - if (new_file_size % (1024*1024)) { - /* round up to nearest 1MB boundary */ - new_file_size = ((new_file_size >> 20) + 1) << 20; - bdrv_truncate(bs->file->bs, new_file_size); - } - } - qemu_vfree(desc_entries); - desc_entries = NULL; - } - - bdrv_flush(bs); - /* 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 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 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 (bs->read_only) { - 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; - cpu_to_le64s(&desc->leading_bytes); - memcpy(sector->data, data, 4084); - data += 4084; - memcpy(&desc->trailing_bytes, data, 4); - cpu_to_le32s(&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 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; - 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 = (offset / VHDX_LOG_SECTOR_SIZE) * 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; - - /* 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 = bdrv_getlength(bs->file->bs), - .last_file_offset = bdrv_getlength(bs->file->bs), - }; - - new_hdr.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_pread(bs->file->bs, file_offset, merged_sector, - VHDX_LOG_SECTOR_SIZE); - 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_pread(bs->file->bs, - file_offset, - merged_sector + trailing_length, - VHDX_LOG_SECTOR_SIZE - trailing_length); - 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 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 */ - bdrv_flush(bs); - 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 */ - bdrv_flush(bs); - ret = vhdx_log_flush(bs, s, &logs); - if (ret < 0) { - goto exit; - } - - s->log = logs.log; - -exit: - return ret; -} - |