From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: John Snow <jsnow@redhat.com>

Date: Mon, 6 Apr 2020 12:17:04 +0200

Subject: [PATCH] drive-mirror: add support for conditional and always bitmap

 sync modes

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Teach mirror two new tricks for using bitmaps:

Always: no matter what, we synchronize the copy_bitmap back to the

sync_bitmap. In effect, this allows us resume a failed mirror at a later

date.

Conditional: On success only, we sync the bitmap. This is akin to

incremental backup modes; we can use this bitmap to later refresh a

successfully created mirror.

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

---

 block/mirror.c | 24 ++++++++++++++++++------

 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c

index 0821214138..c688726fae 100644

--- a/block/mirror.c

+++ b/block/mirror.c

@@ -674,8 +674,6 @@ static int mirror_exit_common(Job *job)

         bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs);

     }

-    bdrv_release_dirty_bitmap(s->dirty_bitmap);

-

     /* Make sure that the source BDS doesn't go away during bdrv_replace_node,

      * before we can call bdrv_drained_end */

     bdrv_ref(src);

@@ -783,6 +781,18 @@ static int mirror_exit_common(Job *job)

     blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort);

     blk_insert_bs(bjob->blk, mirror_top_bs, &error_abort);

+    if (s->sync_bitmap) {

+        if (s->bitmap_mode == BITMAP_SYNC_MODE_ALWAYS ||

+            (s->bitmap_mode == BITMAP_SYNC_MODE_ON_SUCCESS &&

+             job->ret == 0 && ret == 0)) {

+            /* Success; synchronize copy back to sync. */

+            bdrv_clear_dirty_bitmap(s->sync_bitmap, NULL);

+            bdrv_merge_dirty_bitmap(s->sync_bitmap, s->dirty_bitmap,

+                                    NULL, &error_abort);

+        }

+    }

+    bdrv_release_dirty_bitmap(s->dirty_bitmap);

+

     bs_opaque->job = NULL;

     bdrv_drained_end(src);

@@ -1635,10 +1645,6 @@ static BlockJob *mirror_start_job(

                        " sync mode",

                        MirrorSyncMode_str(sync_mode));

             return NULL;

-        } else if (bitmap_mode != BITMAP_SYNC_MODE_NEVER) {

-            error_setg(errp,

-                       "Bitmap Sync Mode '%s' is not supported by Mirror",

-                       BitmapSyncMode_str(bitmap_mode));

         }

     } else if (bitmap) {

         error_setg(errp,

@@ -1655,6 +1661,12 @@ static BlockJob *mirror_start_job(

             return NULL;

         }

         granularity = bdrv_dirty_bitmap_granularity(bitmap);

+

+        if (bitmap_mode != BITMAP_SYNC_MODE_NEVER) {

+            if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, errp)) {

+                return NULL;

+            }

+        }

     } else if (granularity == 0) {

         granularity = bdrv_get_default_bitmap_granularity(target);

     }