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From f02d8f3eb38c3ed03742cbb981823a1917b3c5b2 Mon Sep 17 00:00:00 2001
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From: Jeffrey Cody <jcody@redhat.com>
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Date: Wed, 20 Nov 2013 19:44:00 +0100
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Subject: [PATCH 17/25] block: vhdx write support
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RH-Author: Jeffrey Cody <jcody@redhat.com>
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Message-id: <aa16eed6f83efd7ff007cb38cca8d52f4c696054.1384975172.git.jcody@redhat.com>
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Patchwork-id: 55810
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O-Subject: [RHEL7 qemu-kvm PATCH 17/26] block: vhdx write support
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Bugzilla: 879234
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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This adds support for writing to VHDX image files, using coroutines.
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Writes into the BAT table goes through the VHDX log.  Currently, BAT
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table writes occur when expanding a dynamic VHDX file, and allocating a
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new BAT entry.
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Signed-off-by: Jeff Cody <jcody@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit d92aa8833c051b53d3bf2614ff885df0037f10bb)
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---
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 block/vhdx.c | 212 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
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 block/vhdx.h |   2 +-
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 2 files changed, 209 insertions(+), 5 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/vhdx.c |  212 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
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 block/vhdx.h |    2 +-
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 2 files changed, 209 insertions(+), 5 deletions(-)
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diff --git a/block/vhdx.c b/block/vhdx.c
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index e36c60e..baf8970 100644
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--- a/block/vhdx.c
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+++ b/block/vhdx.c
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@@ -914,7 +914,7 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags,
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         if (payblocks--) {
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             /* payload bat entries */
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             if ((s->bat[i] & VHDX_BAT_STATE_BIT_MASK) ==
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-                    PAYLOAD_BLOCK_FULL_PRESENT) {
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+                    PAYLOAD_BLOCK_FULLY_PRESENT) {
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                 ret = vhdx_region_check(s, s->bat[i] & VHDX_BAT_FILE_OFF_MASK,
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                                         s->block_size);
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                 if (ret < 0) {
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@@ -935,7 +935,7 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags,
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         }
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     }
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-    /* TODO: differencing files, write */
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+    /* TODO: differencing files */
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     /* Disable migration when VHDX images are used */
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     error_set(&s->migration_blocker,
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@@ -1052,7 +1052,7 @@ static coroutine_fn int vhdx_co_readv(BlockDriverState *bs, int64_t sector_num,
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                 /* return zero */
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                 qemu_iovec_memset(&hd_qiov, 0, 0, sinfo.bytes_avail);
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                 break;
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-            case PAYLOAD_BLOCK_FULL_PRESENT:
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+            case PAYLOAD_BLOCK_FULLY_PRESENT:
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                 qemu_co_mutex_unlock(&s->lock);
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                 ret = bdrv_co_readv(bs->file,
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                                     sinfo.file_offset >> BDRV_SECTOR_BITS,
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@@ -1082,7 +1082,43 @@ exit:
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     return ret;
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 }
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+/*
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+ * Allocate a new payload block at the end of the file.
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+ *
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+ * Allocation will happen at 1MB alignment inside the file
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+ *
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+ * Returns the file offset start of the new payload block
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+ */
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+static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s,
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+                                    uint64_t *new_offset)
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+{
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+    *new_offset = bdrv_getlength(bs->file);
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+
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+    /* per the spec, the address for a block is in units of 1MB */
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+    *new_offset = ROUND_UP(*new_offset, 1024 * 1024);
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+
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+    return bdrv_truncate(bs->file, *new_offset + s->block_size);
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+}
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+
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+/*
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+ * Update the BAT table entry with the new file offset, and the new entry
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+ * state */
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+static void vhdx_update_bat_table_entry(BlockDriverState *bs, BDRVVHDXState *s,
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+                                       VHDXSectorInfo *sinfo,
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+                                       uint64_t *bat_entry_le,
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+                                       uint64_t *bat_offset, int state)
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+{
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+    /* The BAT entry is a uint64, with 44 bits for the file offset in units of
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+     * 1MB, and 3 bits for the block state. */
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+    s->bat[sinfo->bat_idx]  = ((sinfo->file_offset>>20) <<
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+                               VHDX_BAT_FILE_OFF_BITS);
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+    s->bat[sinfo->bat_idx] |= state & VHDX_BAT_STATE_BIT_MASK;
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+
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+    *bat_entry_le = cpu_to_le64(s->bat[sinfo->bat_idx]);
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+    *bat_offset = s->bat_offset + sinfo->bat_idx * sizeof(VHDXBatEntry);
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+
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+}
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 /* Per the spec, on the first write of guest-visible data to the file the
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  * data write guid must be updated in the header */
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@@ -1099,7 +1135,175 @@ int vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s)
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 static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num,
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                                       int nb_sectors, QEMUIOVector *qiov)
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 {
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-    return -ENOTSUP;
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+    int ret = -ENOTSUP;
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+    BDRVVHDXState *s = bs->opaque;
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+    VHDXSectorInfo sinfo;
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+    uint64_t bytes_done = 0;
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+    uint64_t bat_entry = 0;
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+    uint64_t bat_entry_offset = 0;
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+    QEMUIOVector hd_qiov;
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+    struct iovec iov1 = { 0 };
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+    struct iovec iov2 = { 0 };
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+    int sectors_to_write;
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+    int bat_state;
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+    uint64_t bat_prior_offset = 0;
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+    bool bat_update = false;
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+
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+    qemu_iovec_init(&hd_qiov, qiov->niov);
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+
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+    qemu_co_mutex_lock(&s->lock);
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+
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+    ret = vhdx_user_visible_write(bs, s);
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+    if (ret < 0) {
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+        goto exit;
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+    }
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+
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+    while (nb_sectors > 0) {
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+        bool use_zero_buffers = false;
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+        bat_update = false;
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+        if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) {
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+            /* not supported yet */
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+            ret = -ENOTSUP;
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+            goto exit;
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+        } else {
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+            vhdx_block_translate(s, sector_num, nb_sectors, &sinfo);
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+            sectors_to_write = sinfo.sectors_avail;
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+
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+            qemu_iovec_reset(&hd_qiov);
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+            /* check the payload block state */
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+            bat_state = s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK;
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+            switch (bat_state) {
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+            case PAYLOAD_BLOCK_ZERO:
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+                /* in this case, we need to preserve zero writes for
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+                 * data that is not part of this write, so we must pad
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+                 * the rest of the buffer to zeroes */
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+
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+                /* if we are on a posix system with ftruncate() that extends
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+                 * a file, then it is zero-filled for us.  On Win32, the raw
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+                 * layer uses SetFilePointer and SetFileEnd, which does not
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+                 * zero fill AFAIK */
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+
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+                /* Queue another write of zero buffers if the underlying file
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+                 * does not zero-fill on file extension */
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+
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+                if (bdrv_has_zero_init(bs->file) == 0) {
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+                    use_zero_buffers = true;
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+
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+                    /* zero fill the front, if any */
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+                    if (sinfo.block_offset) {
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+                        iov1.iov_len = sinfo.block_offset;
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+                        iov1.iov_base = qemu_blockalign(bs, iov1.iov_len);
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+                        memset(iov1.iov_base, 0, iov1.iov_len);
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+                        qemu_iovec_concat_iov(&hd_qiov, &iov1, 1, 0,
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+                                              sinfo.block_offset);
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+                        sectors_to_write += iov1.iov_len >> BDRV_SECTOR_BITS;
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+                    }
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+
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+                    /* our actual data */
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+                    qemu_iovec_concat(&hd_qiov, qiov,  bytes_done,
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+                                      sinfo.bytes_avail);
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+
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+                    /* zero fill the back, if any */
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+                    if ((sinfo.bytes_avail - sinfo.block_offset) <
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+                         s->block_size) {
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+                        iov2.iov_len = s->block_size -
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+                                      (sinfo.bytes_avail + sinfo.block_offset);
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+                        iov2.iov_base = qemu_blockalign(bs, iov2.iov_len);
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+                        memset(iov2.iov_base, 0, iov2.iov_len);
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+                        qemu_iovec_concat_iov(&hd_qiov, &iov2, 1, 0,
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+                                              sinfo.block_offset);
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+                        sectors_to_write += iov2.iov_len >> BDRV_SECTOR_BITS;
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+                    }
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+                }
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+
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+                /* fall through */
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+            case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */
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+            case PAYLOAD_BLOCK_UNMAPPED:    /* fall through */
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+            case PAYLOAD_BLOCK_UNDEFINED:   /* fall through */
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+                bat_prior_offset = sinfo.file_offset;
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+                ret = vhdx_allocate_block(bs, s, &sinfo.file_offset);
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+                if (ret < 0) {
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+                    goto exit;
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+                }
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+                /* once we support differencing files, this may also be
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+                 * partially present */
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+                /* update block state to the newly specified state */
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+                vhdx_update_bat_table_entry(bs, s, &sinfo, &bat_entry,
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+                                            &bat_entry_offset,
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+                                            PAYLOAD_BLOCK_FULLY_PRESENT);
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+                bat_update = true;
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+                /* since we just allocated a block, file_offset is the
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+                 * beginning of the payload block. It needs to be the
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+                 * write address, which includes the offset into the block */
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+                if (!use_zero_buffers) {
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+                    sinfo.file_offset += sinfo.block_offset;
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+                }
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+                /* fall through */
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+            case PAYLOAD_BLOCK_FULLY_PRESENT:
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+                /* if the file offset address is in the header zone,
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+                 * there is a problem */
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+                if (sinfo.file_offset < (1024 * 1024)) {
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+                    ret = -EFAULT;
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+                    goto error_bat_restore;
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+                }
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+
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+                if (!use_zero_buffers) {
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+                    qemu_iovec_concat(&hd_qiov, qiov,  bytes_done,
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+                                      sinfo.bytes_avail);
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+                }
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+                /* block exists, so we can just overwrite it */
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+                qemu_co_mutex_unlock(&s->lock);
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+                ret = bdrv_co_writev(bs->file,
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+                                    sinfo.file_offset >> BDRV_SECTOR_BITS,
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+                                    sectors_to_write, &hd_qiov);
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+                qemu_co_mutex_lock(&s->lock);
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+                if (ret < 0) {
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+                    goto error_bat_restore;
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+                }
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+                break;
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+            case PAYLOAD_BLOCK_PARTIALLY_PRESENT:
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+                /* we don't yet support difference files, fall through
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+                 * to error */
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+            default:
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+                ret = -EIO;
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+                goto exit;
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+                break;
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+            }
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+
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+            if (bat_update) {
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+                /* this will update the BAT entry into the log journal, and
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+                 * then flush the log journal out to disk */
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+                ret =  vhdx_log_write_and_flush(bs, s, &bat_entry,
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+                                                sizeof(VHDXBatEntry),
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+                                                bat_entry_offset);
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+                if (ret < 0) {
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+                    goto exit;
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+                }
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+            }
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+
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+            nb_sectors -= sinfo.sectors_avail;
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+            sector_num += sinfo.sectors_avail;
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+            bytes_done += sinfo.bytes_avail;
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+
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+        }
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+    }
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+
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+    goto exit;
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+
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+error_bat_restore:
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+    if (bat_update) {
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+        /* keep metadata in sync, and restore the bat entry state
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+         * if error. */
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+        sinfo.file_offset = bat_prior_offset;
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+        vhdx_update_bat_table_entry(bs, s, &sinfo, &bat_entry,
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+                                    &bat_entry_offset, bat_state);
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+    }
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+exit:
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+    qemu_vfree(iov1.iov_base);
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+    qemu_vfree(iov2.iov_base);
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+    qemu_co_mutex_unlock(&s->lock);
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+    qemu_iovec_destroy(&hd_qiov);
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+    return ret;
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 }
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diff --git a/block/vhdx.h b/block/vhdx.h
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index 4bb83de..a85c5c8 100644
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--- a/block/vhdx.h
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+++ b/block/vhdx.h
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@@ -217,7 +217,7 @@ typedef struct QEMU_PACKED VHDXLogDataSector {
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 #define PAYLOAD_BLOCK_UNDEFINED         1
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 #define PAYLOAD_BLOCK_ZERO              2
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 #define PAYLOAD_BLOCK_UNMAPPED          5
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-#define PAYLOAD_BLOCK_FULL_PRESENT      6
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+#define PAYLOAD_BLOCK_FULLY_PRESENT     6
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 #define PAYLOAD_BLOCK_PARTIALLY_PRESENT 7
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 #define SB_BLOCK_NOT_PRESENT    0
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-- 
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1.7.1
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