Adding qemu as a submodule of KVMFORNFV

This Patch includes the changes to add qemu as a submodule to
kvmfornfv repo and make use of the updated latest qemu for the
execution of all testcase
Change-Id: I1280af507a857675c7f81d30c95255635667bdd7
Signed-off-by:RajithaY<rajithax.yerrumsetty@intel.com>

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, &sectors_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, &sectors_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, &sectors_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, &sectors_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;
-}
-