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Re: [PATCH v2 10/20] parallels: Add dirty bitmaps saving


From: Alexander Ivanov
Subject: Re: [PATCH v2 10/20] parallels: Add dirty bitmaps saving
Date: Mon, 23 Oct 2023 12:03:01 +0200
User-agent: Mozilla Thunderbird



On 10/21/23 12:40, Mike Maslenkin wrote:
On Thu, Oct 19, 2023 at 4:05 PM Alexander Ivanov
<alexander.ivanov@virtuozzo.com> wrote:
Now dirty bitmaps can be loaded but there is no their saving. Add code for
dirty bitmap storage.

Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
---
  block/parallels-ext.c | 167 ++++++++++++++++++++++++++++++++++++++++++
  block/parallels.c     |  16 +++-
  block/parallels.h     |   5 ++
  3 files changed, 186 insertions(+), 2 deletions(-)

diff --git a/block/parallels-ext.c b/block/parallels-ext.c
index 8a109f005a..0a632a2331 100644
--- a/block/parallels-ext.c
+++ b/block/parallels-ext.c
@@ -24,6 +24,7 @@
   */

  #include "qemu/osdep.h"
+#include "qemu/error-report.h"
  #include "qapi/error.h"
  #include "block/block-io.h"
  #include "block/block_int.h"
@@ -301,3 +302,169 @@ out:

      return ret;
  }
+
+static void parallels_save_bitmap(BlockDriverState *bs, BdrvDirtyBitmap 
*bitmap,
+                                  uint8_t **buf, int *buf_size)
+{
+    BDRVParallelsState *s = bs->opaque;
+    ParallelsFeatureHeader *fh;
+    ParallelsDirtyBitmapFeature *bh;
+    uint64_t *l1_table, l1_size, granularity, limit;
+    int64_t bm_size, ser_size, offset, buf_used;
+    int64_t alloc_size = 1;
+    const char *name;
+    uint8_t *bm_buf;
+    QemuUUID uuid;
+    int ret = 0;
+
+    if (!bdrv_dirty_bitmap_get_persistence(bitmap) ||
+        bdrv_dirty_bitmap_inconsistent(bitmap)) {
+        return;
+    }
+
+    bm_size = bdrv_dirty_bitmap_size(bitmap);
+    granularity = bdrv_dirty_bitmap_granularity(bitmap);
+    limit = bdrv_dirty_bitmap_serialization_coverage(s->cluster_size, bitmap);
+    ser_size = bdrv_dirty_bitmap_serialization_size(bitmap, 0, bm_size);
+    l1_size = DIV_ROUND_UP(ser_size, s->cluster_size);
+
+    buf_used = l1_size * 8 + sizeof(*fh) + sizeof(*bh);
+    /* Check if there is enough space for the final section */
+    if (*buf_size - buf_used < sizeof(*fh)) {
+        return;
+    }
+
+    name = bdrv_dirty_bitmap_name(bitmap);
+    ret = qemu_uuid_parse(name, &uuid);
+    if (ret < 0) {
+        error_report("Can't save dirty bitmap: ID parsing error: '%s'", name);
+        return;
+    }
+
+    fh = (ParallelsFeatureHeader *)*buf;
+    bh = (ParallelsDirtyBitmapFeature *)(*buf + sizeof(*fh));
+    l1_table = (uint64_t *)((uint8_t *)bh + sizeof(*bh));
+
+    fh->magic = cpu_to_le64(PARALLELS_DIRTY_BITMAP_FEATURE_MAGIC);
+    fh->data_size = cpu_to_le32(l1_size * 8 + sizeof(*bh));
+
+    bh->l1_size = cpu_to_le32(l1_size);
+    bh->size = cpu_to_le64(bm_size >> BDRV_SECTOR_BITS);
+    bh->granularity = cpu_to_le32(granularity >> BDRV_SECTOR_BITS);
+    memcpy(bh->id, &uuid, sizeof(uuid));
+
+    bm_buf = qemu_blockalign(bs, s->cluster_size);
+
+    offset = 0;
+    while ((offset = bdrv_dirty_bitmap_next_dirty(bitmap, offset, bm_size)) >= 
0) {
+        uint64_t idx = offset / limit;
+        int64_t cluster_off, end, write_size;
+
+        offset = QEMU_ALIGN_DOWN(offset, limit);
+        end = MIN(bm_size, offset + limit);
+        write_size = bdrv_dirty_bitmap_serialization_size(bitmap, offset,
+                                                          end - offset);
+        assert(write_size <= s->cluster_size);
+
+        bdrv_dirty_bitmap_serialize_part(bitmap, bm_buf, offset, end - offset);
+        if (write_size < s->cluster_size) {
+            memset(bm_buf + write_size, 0, s->cluster_size - write_size);
+        }
+
+        cluster_off = parallels_allocate_host_clusters(bs, &alloc_size);
+        if (cluster_off <= 0) {
+            goto end;
+        }
+
+        ret = bdrv_pwrite(bs->file, cluster_off, s->cluster_size, bm_buf, 0);
+        if (ret < 0) {
+            memset(&fh->magic, 0, sizeof(fh->magic));
+            parallels_mark_unused(bs, s->used_bmap, s->used_bmap_size,
+                                  cluster_off, 1);
+            goto end;
+        }
+
+        l1_table[idx] = cpu_to_le64(cluster_off >> BDRV_SECTOR_BITS);
+        offset = end;
+    }
+
+    *buf_size -= buf_used;
+    *buf += buf_used;
+
+end:
+    qemu_vfree(bm_buf);
+}
+
+void parallels_store_persistent_dirty_bitmaps(BlockDriverState *bs,
+                                              Error **errp)
+{
+    BDRVParallelsState *s = bs->opaque;
+    BdrvDirtyBitmap *bitmap;
+    ParallelsFormatExtensionHeader *eh;
+    int remaining = s->cluster_size;
+    uint8_t *buf, *pos;
+    int64_t header_off, alloc_size = 1;
+    g_autofree uint8_t *hash = NULL;
+    size_t hash_len = 0;
+    int ret;
+
+    s->header->ext_off = 0;
+
+    if (!bdrv_has_named_bitmaps(bs)) {
+        return;
+    }
+
+    buf = qemu_blockalign0(bs, s->cluster_size);
+
+    eh = (ParallelsFormatExtensionHeader *)buf;
+    pos = buf + sizeof(*eh);
+
+    eh->magic = cpu_to_le64(PARALLELS_FORMAT_EXTENSION_MAGIC);
+
+    FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
+        parallels_save_bitmap(bs, bitmap, &pos, &remaining);
+    }
+
+    header_off = parallels_allocate_host_clusters(bs, &alloc_size);
+    if (header_off < 0) {
+        error_report("Can't save dirty bitmap: cluster allocation error");
+        ret = header_off;
+        goto end;
+    }
+
+    ret = qcrypto_hash_bytes(QCRYPTO_HASH_ALG_MD5,
+                             (const char *)(buf + sizeof(*eh)),
+                             s->cluster_size - sizeof(*eh),
+                             &hash, &hash_len, errp);
+    if (ret < 0 || hash_len != sizeof(eh->check_sum)) {
+        error_report("Can't save dirty bitmap: hash error");
+        ret = -EINVAL;
+        goto end;
+    }
+    memcpy(eh->check_sum, hash, hash_len);
+
+    ret = bdrv_pwrite(bs->file, header_off, s->cluster_size, buf, 0);
+    if (ret < 0) {
+        error_report("Can't save dirty bitmap: IO error");
+        parallels_mark_unused(bs, s->used_bmap, s->used_bmap_size,
+                              header_off, 1);
+        goto end;
+    }
+
+    s->header->ext_off = cpu_to_le64(header_off / BDRV_SECTOR_SIZE);
+end:
+    qemu_vfree(buf);
+}
+
+bool coroutine_fn parallels_co_can_store_new_dirty_bitmap(BlockDriverState *bs,
+                                                          const char *name,
+                                                          uint32_t granularity,
+                                                          Error **errp)
+{
+    if (bdrv_find_dirty_bitmap(bs, name)) {
+        error_setg(errp, "Bitmap already exists: %s", name);
+        return false;
+    }
+
+    return true;
+}
diff --git a/block/parallels.c b/block/parallels.c
index 2ee2b42038..bb1e765ec8 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -1470,14 +1470,25 @@ fail:
  static int parallels_inactivate(BlockDriverState *bs)
  {
      BDRVParallelsState *s = bs->opaque;
+    Error *err = NULL;
      int ret;

+    parallels_store_persistent_dirty_bitmaps(bs, &err);
+    if (err != NULL) {
+        error_reportf_err(err, "Lost persistent bitmaps during "
+                          "inactivation of node '%s': ",
+                          bdrv_get_device_or_node_name(bs));
+    }
+
      s->header->inuse = 0;
      parallels_update_header(bs);

Recently bdrv_get_device_or_node_name() calls were guarded by
bdrv_graph_rd{,un}lock_main_loop.
There are no annotations for parallels_close() or
parallels_inactivate(), so may be it should be done in the same way?

Thank you, will take a look.

--
Best regards,
Alexander Ivanov




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