Merge remote-tracking branch 'remotes/jnsnow/tags/bitmaps-pull-reques…

…t' into staging

Pull request

# gpg: Signature made Mon 29 Oct 2018 21:24:08 GMT
# gpg:                using RSA key 7DEF8106AAFC390E
# gpg: Good signature from "John Snow (John Huston) <jsnow@redhat.com>"
# Primary key fingerprint: FAEB 9711 A12C F475 812F  18F2 88A9 064D 1835 61EB
#      Subkey fingerprint: F9B7 ABDB BCAC DF95 BE76  CBD0 7DEF 8106 AAFC 390E

* remotes/jnsnow/tags/bitmaps-pull-request:
  iotests: 169: add cases for source vm resuming
  iotests: improve 169
  dirty-bitmaps: clean-up bitmaps loading and migration logic
  bitmap: Update count after a merge
  nbd: forbid use of frozen bitmaps
  block/backup: prohibit backup from using in use bitmaps
  block/dirty-bitmaps: prohibit enable/disable on locked/frozen bitmaps
  block/dirty-bitmaps: allow clear on disabled bitmaps
  block/dirty-bitmaps: fix merge permissions
  block/dirty-bitmaps: add user_locked status checker
  bloc/qcow2: drop dirty_bitmaps_loaded state variable
  block/qcow2: improve error message in qcow2_inactivate
  iotests: 169: drop deprecated 'autoload' parameter
  qapi: add transaction support for x-block-dirty-bitmap-merge
  blockdev: rename block-dirty-bitmap-clear transaction handlers
  dirty-bitmap: make it possible to restore bitmap after merge
  dirty-bitmap: rename bdrv_undo_clear_dirty_bitmap
  dirty-bitmap: switch assert-fails to errors in bdrv_merge_dirty_bitmap
  blockdev-backup: add bitmap argument

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

block.c

@@ -4403,6 +4403,7 @@ static void coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs,
     uint64_t perm, shared_perm;
     Error *local_err = NULL;
     int ret;
+    BdrvDirtyBitmap *bm;
 
     if (!bs->drv)  {
         return;
@@ -4452,6 +4453,12 @@ static void coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs,
         }
     }
 
+    for (bm = bdrv_dirty_bitmap_next(bs, NULL); bm;
+         bm = bdrv_dirty_bitmap_next(bs, bm))
+    {
+        bdrv_dirty_bitmap_set_migration(bm, false);
+    }
+
     ret = refresh_total_sectors(bs, bs->total_sectors);
     if (ret < 0) {
         bs->open_flags |= BDRV_O_INACTIVE;
@@ -4566,10 +4573,6 @@ static int bdrv_inactivate_recurse(BlockDriverState *bs,
         }
     }
 
-    /* At this point persistent bitmaps should be already stored by the format
-     * driver */
-    bdrv_release_persistent_dirty_bitmaps(bs);
-
     return 0;
 }
 

block/dirty-bitmap.c

@@ -55,6 +55,10 @@ struct BdrvDirtyBitmap {
                                    and this bitmap must remain unchanged while
                                    this flag is set. */
     bool persistent;            /* bitmap must be saved to owner disk image */
+    bool migration;             /* Bitmap is selected for migration, it should
+                                   not be stored on the next inactivation
+                                   (persistent flag doesn't matter until next
+                                   invalidation).*/
     QLIST_ENTRY(BdrvDirtyBitmap) list;
 };
 
@@ -176,6 +180,12 @@ bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap)
     return bitmap->successor;
 }
 
+/* Both conditions disallow user-modification via QMP. */
+bool bdrv_dirty_bitmap_user_locked(BdrvDirtyBitmap *bitmap) {
+    return bdrv_dirty_bitmap_frozen(bitmap) ||
+           bdrv_dirty_bitmap_qmp_locked(bitmap);
+}
+
 void bdrv_dirty_bitmap_set_qmp_locked(BdrvDirtyBitmap *bitmap, bool qmp_locked)
 {
     qemu_mutex_lock(bitmap->mutex);
@@ -314,7 +324,7 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap_locked(BlockDriverState *bs,
         return NULL;
     }
 
-    if (!hbitmap_merge(parent->bitmap, successor->bitmap)) {
+    if (!hbitmap_merge(parent->bitmap, successor->bitmap, parent->bitmap)) {
         error_setg(errp, "Merging of parent and successor bitmap failed");
         return NULL;
     }
@@ -383,26 +393,6 @@ void bdrv_release_named_dirty_bitmaps(BlockDriverState *bs)
     bdrv_dirty_bitmaps_unlock(bs);
 }
 
-/**
- * Release all persistent dirty bitmaps attached to a BDS (for use in
- * bdrv_inactivate_recurse()).
- * There must not be any frozen bitmaps attached.
- * This function does not remove persistent bitmaps from the storage.
- * Called with BQL taken.
- */
-void bdrv_release_persistent_dirty_bitmaps(BlockDriverState *bs)
-{
-    BdrvDirtyBitmap *bm, *next;
-
-    bdrv_dirty_bitmaps_lock(bs);
-    QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, next) {
-        if (bdrv_dirty_bitmap_get_persistance(bm)) {
-            bdrv_release_dirty_bitmap_locked(bm);
-        }
-    }
-    bdrv_dirty_bitmaps_unlock(bs);
-}
-
 /**
  * Remove persistent dirty bitmap from the storage if it exists.
  * Absence of bitmap is not an error, because we have the following scenario:
@@ -619,7 +609,6 @@ void bdrv_reset_dirty_bitmap(BdrvDirtyBitmap *bitmap,
 
 void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap **out)
 {
-    assert(bdrv_dirty_bitmap_enabled(bitmap));
     assert(!bdrv_dirty_bitmap_readonly(bitmap));
     bdrv_dirty_bitmap_lock(bitmap);
     if (!out) {
@@ -633,12 +622,12 @@ void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap **out)
     bdrv_dirty_bitmap_unlock(bitmap);
 }
 
-void bdrv_undo_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap *in)
+void bdrv_restore_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap *backup)
 {
     HBitmap *tmp = bitmap->bitmap;
     assert(bdrv_dirty_bitmap_enabled(bitmap));
     assert(!bdrv_dirty_bitmap_readonly(bitmap));
-    bitmap->bitmap = in;
+    bitmap->bitmap = backup;
     hbitmap_free(tmp);
 }
 
@@ -756,16 +745,24 @@ void bdrv_dirty_bitmap_set_persistance(BdrvDirtyBitmap *bitmap, bool persistent)
     qemu_mutex_unlock(bitmap->mutex);
 }
 
+/* Called with BQL taken. */
+void bdrv_dirty_bitmap_set_migration(BdrvDirtyBitmap *bitmap, bool migration)
+{
+    qemu_mutex_lock(bitmap->mutex);
+    bitmap->migration = migration;
+    qemu_mutex_unlock(bitmap->mutex);
+}
+
 bool bdrv_dirty_bitmap_get_persistance(BdrvDirtyBitmap *bitmap)
 {
-    return bitmap->persistent;
+    return bitmap->persistent && !bitmap->migration;
 }
 
 bool bdrv_has_changed_persistent_bitmaps(BlockDriverState *bs)
 {
     BdrvDirtyBitmap *bm;
     QLIST_FOREACH(bm, &bs->dirty_bitmaps, list) {
-        if (bm->persistent && !bm->readonly) {
+        if (bm->persistent && !bm->readonly && !bm->migration) {
             return true;
         }
     }
@@ -791,19 +788,41 @@ int64_t bdrv_dirty_bitmap_next_zero(BdrvDirtyBitmap *bitmap, uint64_t offset)
 }
 
 void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src,
-                             Error **errp)
+                             HBitmap **backup, Error **errp)
 {
+    bool ret;
+
     /* only bitmaps from one bds are supported */
     assert(dest->mutex == src->mutex);
 
     qemu_mutex_lock(dest->mutex);
 
-    assert(bdrv_dirty_bitmap_enabled(dest));
-    assert(!bdrv_dirty_bitmap_readonly(dest));
+    if (bdrv_dirty_bitmap_user_locked(dest)) {
+        error_setg(errp, "Bitmap '%s' is currently in use by another"
+        " operation and cannot be modified", dest->name);
+        goto out;
+    }
+
+    if (bdrv_dirty_bitmap_readonly(dest)) {
+        error_setg(errp, "Bitmap '%s' is readonly and cannot be modified",
+                   dest->name);
+        goto out;
+    }
 
-    if (!hbitmap_merge(dest->bitmap, src->bitmap)) {
+    if (!hbitmap_can_merge(dest->bitmap, src->bitmap)) {
         error_setg(errp, "Bitmaps are incompatible and can't be merged");
+        goto out;
+    }
+
+    if (backup) {
+        *backup = dest->bitmap;
+        dest->bitmap = hbitmap_alloc(dest->size, hbitmap_granularity(*backup));
+        ret = hbitmap_merge(*backup, src->bitmap, dest->bitmap);
+    } else {
+        ret = hbitmap_merge(dest->bitmap, src->bitmap, dest->bitmap);
     }
+    assert(ret);
 
+out:
     qemu_mutex_unlock(dest->mutex);
 }

block/qcow2-bitmap.c

@@ -1418,6 +1418,22 @@ void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp)
         g_free(tb);
     }
 
+    QSIMPLEQ_FOREACH(bm, bm_list, entry) {
+        /* For safety, we remove bitmap after storing.
+         * We may be here in two cases:
+         * 1. bdrv_close. It's ok to drop bitmap.
+         * 2. inactivation. It means migration without 'dirty-bitmaps'
+         *    capability, so bitmaps are not marked with
+         *    BdrvDirtyBitmap.migration flags. It's not bad to drop them too,
+         *    and reload on invalidation.
+         */
+        if (bm->dirty_bitmap == NULL) {
+            continue;
+        }
+
+        bdrv_release_dirty_bitmap(bs, bm->dirty_bitmap);
+    }
+
     bitmap_list_free(bm_list);
     return;
 

block/qcow2.c

@@ -1153,7 +1153,6 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
     uint64_t ext_end;
     uint64_t l1_vm_state_index;
     bool update_header = false;
-    bool header_updated = false;
 
     ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
     if (ret < 0) {
@@ -1492,23 +1491,70 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
         s->autoclear_features &= QCOW2_AUTOCLEAR_MASK;
     }
 
-    if (s->dirty_bitmaps_loaded) {
-        /* It's some kind of reopen. There are no known cases where we need to
-         * reload bitmaps in such a situation, so it's safer to skip them.
-         *
-         * Moreover, if we have some readonly bitmaps and we are reopening for
-         * rw we should reopen bitmaps correspondingly.
-         */
-        if (bdrv_has_readonly_bitmaps(bs) &&
-            !bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIVE))
-        {
-            qcow2_reopen_bitmaps_rw_hint(bs, &header_updated, &local_err);
-        }
-    } else {
-        header_updated = qcow2_load_dirty_bitmaps(bs, &local_err);
-        s->dirty_bitmaps_loaded = true;
+    /* == Handle persistent dirty bitmaps ==
+     *
+     * We want load dirty bitmaps in three cases:
+     *
+     * 1. Normal open of the disk in active mode, not related to invalidation
+     *    after migration.
+     *
+     * 2. Invalidation of the target vm after pre-copy phase of migration, if
+     *    bitmaps are _not_ migrating through migration channel, i.e.
+     *    'dirty-bitmaps' capability is disabled.
+     *
+     * 3. Invalidation of source vm after failed or canceled migration.
+     *    This is a very interesting case. There are two possible types of
+     *    bitmaps:
+     *
+     *    A. Stored on inactivation and removed. They should be loaded from the
+     *       image.
+     *
+     *    B. Not stored: not-persistent bitmaps and bitmaps, migrated through
+     *       the migration channel (with dirty-bitmaps capability).
+     *
+     *    On the other hand, there are two possible sub-cases:
+     *
+     *    3.1 disk was changed by somebody else while were inactive. In this
+     *        case all in-RAM dirty bitmaps (both persistent and not) are
+     *        definitely invalid. And we don't have any method to determine
+     *        this.
+     *
+     *        Simple and safe thing is to just drop all the bitmaps of type B on
+     *        inactivation. But in this case we lose bitmaps in valid 4.2 case.
+     *
+     *        On the other hand, resuming source vm, if disk was already changed
+     *        is a bad thing anyway: not only bitmaps, the whole vm state is
+     *        out of sync with disk.
+     *
+     *        This means, that user or management tool, who for some reason
+     *        decided to resume source vm, after disk was already changed by
+     *        target vm, should at least drop all dirty bitmaps by hand.
+     *
+     *        So, we can ignore this case for now, but TODO: "generation"
+     *        extension for qcow2, to determine, that image was changed after
+     *        last inactivation. And if it is changed, we will drop (or at least
+     *        mark as 'invalid' all the bitmaps of type B, both persistent
+     *        and not).
+     *
+     *    3.2 disk was _not_ changed while were inactive. Bitmaps may be saved
+     *        to disk ('dirty-bitmaps' capability disabled), or not saved
+     *        ('dirty-bitmaps' capability enabled), but we don't need to care
+     *        of: let's load bitmaps as always: stored bitmaps will be loaded,
+     *        and not stored has flag IN_USE=1 in the image and will be skipped
+     *        on loading.
+     *
+     * One remaining possible case when we don't want load bitmaps:
+     *
+     * 4. Open disk in inactive mode in target vm (bitmaps are migrating or
+     *    will be loaded on invalidation, no needs try loading them before)
+     */
+
+    if (!(bdrv_get_flags(bs) & BDRV_O_INACTIVE)) {
+        /* It's case 1, 2 or 3.2. Or 3.1 which is BUG in management layer. */
+        bool header_updated = qcow2_load_dirty_bitmaps(bs, &local_err);
+
+        update_header = update_header && !header_updated;
     }
-    update_header = update_header && !header_updated;
     if (local_err != NULL) {
         error_propagate(errp, local_err);
         ret = -EINVAL;
@@ -2123,9 +2169,9 @@ static int qcow2_inactivate(BlockDriverState *bs)
     qcow2_store_persistent_dirty_bitmaps(bs, &local_err);
     if (local_err != NULL) {
         result = -EINVAL;
-        error_report_err(local_err);
-        error_report("Persistent bitmaps are lost for node '%s'",
-                     bdrv_get_device_or_node_name(bs));
+        error_reportf_err(local_err, "Lost persistent bitmaps during "
+                          "inactivation of node '%s': ",
+                          bdrv_get_device_or_node_name(bs));
     }
 
     ret = qcow2_cache_flush(bs, s->l2_table_cache);

block/qcow2.h

@@ -300,7 +300,6 @@ typedef struct BDRVQcow2State {
     uint32_t nb_bitmaps;
     uint64_t bitmap_directory_size;
     uint64_t bitmap_directory_offset;
-    bool dirty_bitmaps_loaded;
 
     int flags;
     int qcow_version;