Merge remote-tracking branch 'remotes/jnsnow/tags/bitmaps-pull-request' into staging

Pull request

# gpg: Signature made Wed 20 Feb 2019 18:01:00 GMT
# gpg:                using RSA key F9B7ABDBBCACDF95BE76CBD07DEF8106AAFC390E
# gpg: Good signature from "John Snow (John Huston) <jsnow@redhat.com>" [full]
# 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:
  blockdev: acquire aio_context for bitmap add/remove
  block/dirty-bitmap: Documentation and Comment fixups
  dirty-bitmap: Expose persistent flag to 'query-block'

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

5 files changed, 79 insertions, 22 deletions

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 00ea36f554..c6d4acebfa 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -29,12 +29,20 @@
 #include "block/blockjob.h"
 
 /**
- * A BdrvDirtyBitmap can be in three possible states:
- * (1) successor is NULL and disabled is false: full r/w mode
- * (2) successor is NULL and disabled is true: read only mode ("disabled")
- * (3) successor is set: frozen mode.
- *     A frozen bitmap cannot be renamed, deleted, anonymized, cleared, set,
- *     or enabled. A frozen bitmap can only abdicate() or reclaim().
+ * A BdrvDirtyBitmap can be in four possible user-visible states:
+ * (1) Active:   successor is NULL, and disabled is false: full r/w mode
+ * (2) Disabled: successor is NULL, and disabled is true: qualified r/w mode,
+ *               guest writes are dropped, but monitor writes are possible,
+ *               through commands like merge and clear.
+ * (3) Frozen:   successor is not NULL.
+ *               A frozen bitmap cannot be renamed, deleted, cleared, set,
+ *               enabled, merged to, etc. A frozen bitmap can only abdicate()
+ *               or reclaim().
+ *               In this state, the anonymous successor bitmap may be either
+ *               Active and recording writes from the guest (e.g. backup jobs),
+ *               but it can be Disabled and not recording writes.
+ * (4) Locked:   Whether Active or Disabled, the user cannot modify this bitmap
+ *               in any way from the monitor.
  */
 struct BdrvDirtyBitmap {
     QemuMutex *mutex;
@@ -440,6 +448,7 @@ BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs)
         info->has_name = !!bm->name;
         info->name = g_strdup(bm->name);
         info->status = bdrv_dirty_bitmap_status(bm);
+        info->persistent = bm->persistent;
         entry->value = info;
         *plist = entry;
         plist = &entry->next;
diff --git a/blockdev.c b/blockdev.c
index fb18e9c975..8714ad2702 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2820,6 +2820,7 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
 {
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
+    AioContext *aio_context = NULL;
 
     if (!name || name[0] == '\0') {
         error_setg(errp, "Bitmap name cannot be empty");
@@ -2854,15 +2855,17 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
         disabled = false;
     }
 
-    if (persistent &&
-        !bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp))
-    {
-        return;
+    if (persistent) {
+        aio_context = bdrv_get_aio_context(bs);
+        aio_context_acquire(aio_context);
+        if (!bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp)) {
+            goto out;
+        }
     }
 
     bitmap = bdrv_create_dirty_bitmap(bs, granularity, name, errp);
     if (bitmap == NULL) {
-        return;
+        goto out;
     }
 
     if (disabled) {
@@ -2870,6 +2873,10 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
     }
 
     bdrv_dirty_bitmap_set_persistance(bitmap, persistent);
+ out:
+    if (aio_context) {
+        aio_context_release(aio_context);
+    }
 }
 
 void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
@@ -2878,6 +2885,7 @@ void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
     Error *local_err = NULL;
+    AioContext *aio_context = NULL;
 
     bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
     if (!bitmap || !bs) {
@@ -2892,14 +2900,20 @@ void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
     }
 
     if (bdrv_dirty_bitmap_get_persistance(bitmap)) {
+        aio_context = bdrv_get_aio_context(bs);
+        aio_context_acquire(aio_context);
         bdrv_remove_persistent_dirty_bitmap(bs, name, &local_err);
         if (local_err != NULL) {
             error_propagate(errp, local_err);
-            return;
+            goto out;
         }
     }
 
     bdrv_release_dirty_bitmap(bs, bitmap);
+ out:
+    if (aio_context) {
+        aio_context_release(aio_context);
+    }
 }
 
 /**
diff --git a/qapi/block-core.json b/qapi/block-core.json
index ee1ab7a8a2..2b8afbb924 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -420,17 +420,27 @@
 #
 # An enumeration of possible states that a dirty bitmap can report to the user.
 #
-# @frozen: The bitmap is currently in-use by a backup operation or block job,
-#          and is immutable.
-#
-# @disabled: The bitmap is currently in-use by an internal operation and is
-#            read-only. It can still be deleted.
+# @frozen: The bitmap is currently in-use by some operation and is immutable.
+#          If the bitmap was @active prior to the operation, new writes by the
+#          guest are being recorded in a temporary buffer, and will not be lost.
+#          Generally, bitmaps are cleared on successful use in an operation and
+#          the temporary buffer is committed into the bitmap. On failure, the
+#          temporary buffer is merged back into the bitmap without first
+#          clearing it.
+#          Please refer to the documentation for each bitmap-using operation,
+#          See also @blockdev-backup, @drive-backup.
+#
+# @disabled: The bitmap is not currently recording new writes by the guest.
+#            This is requested explicitly via @block-dirty-bitmap-disable.
+#            It can still be cleared, deleted, or used for backup operations.
 #
 # @active: The bitmap is actively monitoring for new writes, and can be cleared,
 #          deleted, or used for backup operations.
 #
-# @locked: The bitmap is currently in-use by some operation and can not be
-#          cleared, deleted, or used for backup operations. (Since 2.12)
+# @locked: The bitmap is currently in-use by some operation and is immutable.
+#          If the bitmap was @active prior to the operation, it is still
+#          recording new writes. If the bitmap was @disabled, it is not
+#          recording new writes. (Since 2.12)
 #
 # Since: 2.4
 ##
@@ -450,11 +460,14 @@
 #
 # @status: current status of the dirty bitmap (since 2.4)
 #
+# @persistent: true if the bitmap will eventually be flushed to persistent
+#              storage (since 4.0)
+#
 # Since: 1.3
 ##
 { 'struct': 'BlockDirtyInfo',
   'data': {'*name': 'str', 'count': 'int', 'granularity': 'uint32',
-           'status': 'DirtyBitmapStatus'} }
+           'status': 'DirtyBitmapStatus', 'persistent': 'bool' } }
 
 ##
 # @Qcow2BitmapInfoFlags:
@@ -2091,9 +2104,15 @@
 # @block-dirty-bitmap-merge:
 #
 # Merge dirty bitmaps listed in @bitmaps to the @target dirty bitmap.
-# The @bitmaps dirty bitmaps are unchanged.
+# Dirty bitmaps in @bitmaps will be unchanged, except if it also appears
+# as the @target bitmap. Any bits already set in @target will still be
+# set after the merge, i.e., this operation does not clear the target.
 # On error, @target is unchanged.
 #
+# The resulting bitmap will count as dirty any clusters that were dirty in any
+# of the source bitmaps. This can be used to achieve backup checkpoints, or in
+# simpler usages, to copy bitmaps.
+#
 # Returns: nothing on success
 #          If @node is not a valid block device, DeviceNotFound
 #          If any bitmap in @bitmaps or @target is not found, GenericError
@@ -2128,7 +2147,7 @@
 ##
 # @x-debug-block-dirty-bitmap-sha256:
 #
-# Get bitmap SHA256
+# Get bitmap SHA256.
 #
 # Returns: BlockDirtyBitmapSha256 on success
 #          If @node is not a valid block device, DeviceNotFound
diff --git a/tests/qemu-iotests/124 b/tests/qemu-iotests/124
index 9f189e3b54..5aa1bf1bd6 100755
--- a/tests/qemu-iotests/124
+++ b/tests/qemu-iotests/124
@@ -350,6 +350,7 @@ class TestIncrementalBackup(TestIncrementalBackupBase):
         self.assert_qmp(result, 'return[0]/dirty-bitmaps[0]/count', 458752)
         self.assert_qmp(result, 'return[0]/dirty-bitmaps[0]/granularity', 65536)
         self.assert_qmp(result, 'return[0]/dirty-bitmaps[0]/status', 'active')
+        self.assert_qmp(result, 'return[0]/dirty-bitmaps[0]/persistent', False)
 
         # Prepare a cluster_size=128k backup target without a backing file.
         (target, _) = bitmap0.new_target()
diff --git a/tests/qemu-iotests/236.out b/tests/qemu-iotests/236.out
index bb2d71ea5e..5006f7bca1 100644
--- a/tests/qemu-iotests/236.out
+++ b/tests/qemu-iotests/236.out
@@ -25,12 +25,14 @@ write -P0xcd 0x3ff0000 64k
         "count": 262144,
         "granularity": 65536,
         "name": "bitmapB",
+        "persistent": false,
         "status": "active"
       },
       {
         "count": 262144,
         "granularity": 65536,
         "name": "bitmapA",
+        "persistent": false,
         "status": "active"
       }
     ]
@@ -85,12 +87,14 @@ write -P0xcd 0x3ff0000 64k
         "count": 262144,
         "granularity": 65536,
         "name": "bitmapB",
+        "persistent": false,
         "status": "active"
       },
       {
         "count": 262144,
         "granularity": 65536,
         "name": "bitmapA",
+        "persistent": false,
         "status": "active"
       }
     ]
@@ -183,18 +187,21 @@ write -P0xea 0x3fe0000 64k
         "count": 393216,
         "granularity": 65536,
         "name": "bitmapC",
+        "persistent": false,
         "status": "disabled"
       },
       {
         "count": 262144,
         "granularity": 65536,
         "name": "bitmapB",
+        "persistent": false,
         "status": "disabled"
       },
       {
         "count": 458752,
         "granularity": 65536,
         "name": "bitmapA",
+        "persistent": false,
         "status": "disabled"
       }
     ]
@@ -247,18 +254,21 @@ write -P0xea 0x3fe0000 64k
         "count": 393216,
         "granularity": 65536,
         "name": "bitmapC",
+        "persistent": false,
         "status": "disabled"
       },
       {
         "count": 262144,
         "granularity": 65536,
         "name": "bitmapB",
+        "persistent": false,
         "status": "disabled"
       },
       {
         "count": 458752,
         "granularity": 65536,
         "name": "bitmapA",
+        "persistent": false,
         "status": "disabled"
       }
     ]
@@ -304,24 +314,28 @@ write -P0xea 0x3fe0000 64k
         "count": 458752,
         "granularity": 65536,
         "name": "bitmapD",
+        "persistent": false,
         "status": "disabled"
       },
       {
         "count": 393216,
         "granularity": 65536,
         "name": "bitmapC",
+        "persistent": false,
         "status": "disabled"
       },
       {
         "count": 262144,
         "granularity": 65536,
         "name": "bitmapB",
+        "persistent": false,
         "status": "disabled"
       },
       {
         "count": 458752,
         "granularity": 65536,
         "name": "bitmapA",
+        "persistent": false,
         "status": "disabled"
       }
     ]