--- /dev/null
+/*
+ * 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-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, 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, 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, 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,
+ 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, 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)) {
+ 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) < 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, 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_errno(errp, EPERM,
+ "VHDX image file '%s' opened read-only, but "
+ "contains a log that needs to be replayed. To "
+ "replay the log, execute:\n qemu-img check -r "
+ "all '%s'",
+ bs->filename, 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),
+ .last_file_offset = bdrv_getlength(bs->file),
+ };
+
+ 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, 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,
+ 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;
+}
+
Code Review / kvmfornfv.git / blobdiff