[Qemu-devel] [PATCH 2/6] qmp: add query-block-dirty-bitmap-ranges

[Vladimir Sementsov-Ogievskiy]

Add qmp command to query dirty bitmap contents. This is needed for
external backup.

Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 block/dirty-bitmap.c         | 55 +++++++++++++++++++++++++++++++++++++++
 blockdev.c                   | 62 ++++++++++++++++++++++++++++++++++++++++++++
 include/block/dirty-bitmap.h |  7 +++++
 qapi/block-core.json         | 54 ++++++++++++++++++++++++++++++++++++++
 qmp-commands.hx              | 33 +++++++++++++++++++++++
 5 files changed, 211 insertions(+)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 6da27d9..4c108e4 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -495,3 +495,58 @@ int64_t bdrv_dirty_bitmap_next_zero(BdrvDirtyBitmap 
*bitmap, uint64_t start)
 {
     return hbitmap_next_zero(bitmap->bitmap, start);
 }
+
+/* bdrv_query_dirty_bitmap_ranges
+ * start, count and resulting ranges are all in bytes
+ */
+BlockDirtyRangeList *bdrv_query_dirty_bitmap_ranges(BlockDriverState *bs,
+        BdrvDirtyBitmap *bitmap, uint64_t start, uint64_t count,
+        uint32_t max_ranges)
+{
+    BlockDirtyRangeList *list = NULL, *last_entry = NULL;
+    BlockDirtyRangeList **plist = &list;
+    uint64_t begin, end;
+    uint64_t start_sector = start >> BDRV_SECTOR_BITS;
+    uint64_t last_sector = (start + count - 1) >> BDRV_SECTOR_BITS;
+    uint32_t nb_ranges = 0;
+
+    BdrvDirtyBitmapIter *it = bdrv_dirty_iter_new(bitmap, start_sector);
+
+    while ((begin = bdrv_dirty_iter_next(it)) != -1 && nb_ranges < max_ranges) 
{
+        BlockDirtyRange *region;
+        if (begin > last_sector) {
+            break;
+        }
+
+        end = bdrv_dirty_bitmap_next_zero(bitmap, begin + 1);
+
+        region = g_new0(BlockDirtyRange, 1);
+        region->start = begin << BDRV_SECTOR_BITS;
+        region->count = (end - begin) << BDRV_SECTOR_BITS;
+
+        last_entry = g_new0(BlockDirtyRangeList, 1);
+        last_entry->value = region;
+
+        *plist = last_entry;
+        plist = &last_entry->next;
+        nb_ranges++;
+
+        bdrv_set_dirty_iter(it, end + 1);
+    }
+
+    bdrv_dirty_iter_free(it);
+
+    if (list != NULL) {
+        if (list->value->start < start) {
+            list->value->count -= start - list->value->start;
+            list->value->start = start;
+        }
+
+        if (last_entry->value->start +
+            last_entry->value->count > start + count) {
+            last_entry->value->count = start + count - 
last_entry->value->start;
+        }
+    }
+
+    return list;
+}
diff --git a/blockdev.c b/blockdev.c
index 1392fff..fa34cf6 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2733,6 +2733,68 @@ void qmp_block_dirty_bitmap_clear(const char *node, 
const char *name,
     aio_context_release(aio_context);
 }
 
+BlockDirtyRangeList *qmp_query_block_dirty_bitmap_ranges(const char *node,
+        const char *name, bool has_start, uint64_t start, bool has_count,
+        uint64_t count, uint32_t max_ranges, bool has_block_io, bool block_io,
+        Error **errp)
+{
+    AioContext *aio_context;
+    BdrvDirtyBitmap *bitmap;
+    BlockDriverState *bs;
+    BlockDirtyRangeList *ret = NULL;
+    int64_t disk_size;
+
+    if (!has_block_io) {
+        block_io = true;
+    }
+
+    bitmap = block_dirty_bitmap_lookup(node, name, &bs,
+                                       block_io ? &aio_context : NULL,
+                                       errp);
+    if (!bitmap) {
+        return NULL;
+    }
+
+    if (!block_io && bdrv_dirty_bitmap_enabled(bitmap)) {
+        error_setg(errp, "The bitmap is enabled, block-io must be on");
+        return NULL;
+    }
+
+    disk_size = bdrv_getlength(bs);
+    if (disk_size < 0) {
+        error_setg_errno(errp, -disk_size, "bdrv_getlength failed");
+        goto out;
+    }
+
+    if (has_start) {
+        if (start >= disk_size) {
+            error_setg(errp, "Start must be less than disk size");
+            goto out;
+        }
+    } else {
+        start = 0;
+    }
+
+    if (has_count) {
+        if (start + count > disk_size) {
+            error_setg(errp,
+                       "(start + count) must not be greater than disk size");
+            goto out;
+        }
+    } else {
+        count = disk_size - start;
+    }
+
+    ret = bdrv_query_dirty_bitmap_ranges(bs, bitmap, start, count, max_ranges);
+
+out:
+    if (block_io) {
+        aio_context_release(aio_context);
+    }
+
+    return ret;
+}
+
 void hmp_drive_del(Monitor *mon, const QDict *qdict)
 {
     const char *id = qdict_get_str(qdict, "id");
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index 0033942..7918310 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -70,4 +70,11 @@ void bdrv_dirty_bitmap_deserialize_finish(BdrvDirtyBitmap 
*bitmap);
 
 int64_t bdrv_dirty_bitmap_next_zero(BdrvDirtyBitmap *bitmap, uint64_t start);
 
+/* bdrv_query_dirty_bitmap_ranges
+ * start, count and resulting ranges are all in bytes
+ */
+BlockDirtyRangeList *bdrv_query_dirty_bitmap_ranges(BlockDriverState *bs,
+        BdrvDirtyBitmap *bitmap, uint64_t start, uint64_t count,
+        uint32_t max_ranges);
+
 #endif
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 0a915ed..89bdeaf 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -414,6 +414,60 @@
 ##
 { 'command': 'query-block', 'returns': ['BlockInfo'] }
 
+##
+# @BlockDirtyRegion:
+#
+# Region in bytes.
+#
+# @start: first byte
+#
+# @count: number of bytes in the region
+#
+# Since: 2.6
+##
+{ 'struct': 'BlockDirtyRange',
+  'data': { 'start': 'uint64', 'count': 'uint64' } }
+
+##
+# @BlockDirtyBitmapQueryRanges
+#
+# @node: name of device/node which the bitmap is tracking
+#
+# @name: name of the dirty bitmap
+#
+# @start: #optional start of quered range, default is zero for
+#         query-block-dirty-bitmap-ranges
+#
+# @count: #optional lenght of quered range, default is (disk-size - @start)
+#         for query-block-dirty-bitmap-ranges
+#
+# @max-ranges: max dirty ranges to be returned. If there are more than
+#              @max-ranges dirty ranges within quered range, then first
+#              @max-ranges dirty ranges from quered range will be returned.
+#
+# @block-io: #optional wheter aio-context should be acquired while oparating.
+#            False value is allowed only for frozen or disabled bitmaps.
+#            Default is true for query-block-dirty-bitmap-ranges.
+#
+# Since 2.6
+##
+{ 'struct': 'BlockDirtyBitmapQueryRanges',
+  'data': { 'node': 'str', 'name': 'str', '*start': 'uint64',
+            '*count': 'uint64', 'max-ranges': 'uint32', '*block-io': 'bool'} }
+
+##
+# @query-block-dirty-bitmap-ranges
+#
+# Get a description for specified dirty bitmap including it's dirty regions.
+# This command is in general for testing purposes.
+#
+# Returns: @BlockDirtyBitmapInfo
+#
+# Since: 2.6
+##
+{ 'command': 'query-block-dirty-bitmap-ranges',
+  'data': 'BlockDirtyBitmapQueryRanges',
+  'returns': ['BlockDirtyRange'] }
 
 ##
 # @BlockDeviceTimedStats:
diff --git a/qmp-commands.hx b/qmp-commands.hx
index db072a6..02de44c 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1457,6 +1457,39 @@ Example:
 EQMP
 
     {
+        .name       = "query-block-dirty-bitmap-ranges",
+        .args_type  = "node:B,name:s,start:i?,count:i?,max-ranges:i,"
+                      "block-io:b?",
+        .mhandler.cmd_new = qmp_marshal_query_block_dirty_bitmap_ranges,
+    },
+
+SQMP
+
+query-block-dirty-bitmap-ranges
+------------------------
+Since 2.6
+
+Get contens of specified dirty bitmap. Bitmap data is returned as array of
+dirty ranges.
+
+Arguments:
+
+- "node": device/node on which to remove dirty bitmap (json-string)
+- "name": name of the dirty bitmap (json-string)
+- "start": start of quered range in bytes (json-int, optional, default 0)
+- "count": lenght of quered range in bytes
+           (json-int, optional, default (disk-size - @start))
+- "max-ranges": max dirty ranges to be returned. If there are more than
+                @max-ranges dirty ranges within quered range, then first
+                @max-ranges dirty ranges from quered range will be returned.
+                (json-int)
+- "block-io": wheter aio-context should be acquired while oparating. False
+              value is allowed only for frozen or disabled bitmaps.
+              (json-bool, optional, default true)
+
+EQMP
+
+    {
         .name       = "blockdev-snapshot-sync",
         .args_type  = 
"device:s?,node-name:s?,snapshot-file:s,snapshot-node-name:s?,format:s?,mode:s?",
         .mhandler.cmd_new = qmp_marshal_blockdev_snapshot_sync,
-- 
1.8.3.1