qapi: backup: add max-chunk and max-workers to x-perf struct

Add new parameters to configure future backup features. The patch
doesn't introduce aio backup requests (so we actually have only one
worker) neither requests larger than one cluster. Still, formally we
satisfy these maximums anyway, so add the parameters now, to facilitate
further patch which will really change backup job behavior.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-11-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

diff --git a/block/backup.c b/block/backup.c
index 09ff5a92efdeda9e632b5b85d935ef0d439b0979..5522c0f3fe87a6a86d4e607215b9763e8fabf482 100644 (file)
--- a/block/backup.c
+++ b/block/backup.c
@@ -388,6 +388,29 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
         return NULL;
     }
 
+    cluster_size = backup_calculate_cluster_size(target, errp);
+    if (cluster_size < 0) {
+        goto error;
+    }
+
+    if (perf->max_workers < 1) {
+        error_setg(errp, "max-workers must be greater than zero");
+        return NULL;
+    }
+
+    if (perf->max_chunk < 0) {
+        error_setg(errp, "max-chunk must be zero (which means no limit) or "
+                   "positive");
+        return NULL;
+    }
+
+    if (perf->max_chunk && perf->max_chunk < cluster_size) {
+        error_setg(errp, "Required max-chunk (%" PRIi64 ") is less than backup "
+                   "cluster size (%" PRIi64 ")", perf->max_chunk, cluster_size);
+        return NULL;
+    }
+
+
     if (sync_bitmap) {
         /* If we need to write to this bitmap, check that we can: */
         if (bitmap_mode != BITMAP_SYNC_MODE_NEVER &&
@@ -420,11 +443,6 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
         goto error;
     }
 
-    cluster_size = backup_calculate_cluster_size(target, errp);
-    if (cluster_size < 0) {
-        goto error;
-    }
-
     /*
      * If source is in backing chain of target assume that target is going to be
      * used for "image fleecing", i.e. it should represent a kind of snapshot of

diff --git a/block/replication.c b/block/replication.c
index 22ffc811eef2bbc56054700b52537c469db0bc34..97be7ef4de54686705c833dced03187f5cb222b8 100644 (file)
--- a/block/replication.c
+++ b/block/replication.c
@@ -454,7 +454,7 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
     int64_t active_length, hidden_length, disk_length;
     AioContext *aio_context;
     Error *local_err = NULL;
-    BackupPerf perf = { .use_copy_range = true };
+    BackupPerf perf = { .use_copy_range = true, .max_workers = 1 };
 
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);

diff --git a/blockdev.c b/blockdev.c
index fc88dc03e1338f458b8ab085462e8aac54a02298..25aaacf2535f2e08291fbb04d88ce486f593ecfc 100644 (file)
--- a/blockdev.c
+++ b/blockdev.c
@@ -2829,7 +2829,7 @@ static BlockJob *do_backup_common(BackupCommon *backup,
 {
     BlockJob *job = NULL;
     BdrvDirtyBitmap *bmap = NULL;
-    BackupPerf perf = { .use_copy_range = true };
+    BackupPerf perf = { .use_copy_range = true, .max_workers = 64 };
     int job_flags = JOB_DEFAULT;
 
     if (!backup->has_speed) {
@@ -2858,6 +2858,12 @@ static BlockJob *do_backup_common(BackupCommon *backup,
         if (backup->x_perf->has_use_copy_range) {
             perf.use_copy_range = backup->x_perf->use_copy_range;
         }
+        if (backup->x_perf->has_max_workers) {
+            perf.max_workers = backup->x_perf->max_workers;
+        }
+        if (backup->x_perf->has_max_chunk) {
+            perf.max_chunk = backup->x_perf->max_chunk;
+        }
     }
 
     if ((backup->sync == MIRROR_SYNC_MODE_BITMAP) ||

diff --git a/qapi/block-core.json b/qapi/block-core.json
index 83f661d7f6b4a9b197f672e7620cd9dd0309b6bd..abcd41ed63062dfa5bcb7e0150d6733787fa2c91 100644 (file)
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1379,10 +1379,21 @@
 #
 # @use-copy-range: Use copy offloading. Default true.
 #
+# @max-workers: Maximum number of parallel requests for the sustained background
+#               copying process. Doesn't influence copy-before-write operations.
+#               Default 64.
+#
+# @max-chunk: Maximum request length for the sustained background copying
+#             process. Doesn't influence copy-before-write operations.
+#             0 means unlimited. If max-chunk is non-zero then it should not be
+#             less than job cluster size which is calculated as maximum of
+#             target image cluster size and 64k. Default 0.
+#
 # Since: 6.0
 ##
 { 'struct': 'BackupPerf',
-  'data': { '*use-copy-range': 'bool' }}
+  'data': { '*use-copy-range': 'bool',
+            '*max-workers': 'int', '*max-chunk': 'int64' } }
 
 ##
 # @BackupCommon: