commit eee13dfe302833944d1176677d12a6ea421a94ea
author Paolo Bonzini <pbonzini@redhat.com> Mon Jan 21 17:09:46 2013 +0100
committer Kevin Wolf <kwolf@redhat.com> Fri Jan 25 18:18:34 2013 +0100
tree 53581a0a6c022df243eabdf32cf8e03232113c1c
parent 50717e941b9f306a45292621999eeafbaa954418

mirror: allow customizing the granularity

The desired granularity may be very different depending on the kind of
operation (e.g. continuous replication vs. collapse-to-raw) and whether
the VM is expected to perform lots of I/O while mirroring is in progress.

Allow the user to customize it, while providing a sane default so that
in general there will be no extra allocated space in the target compared
to the source.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

blockdev.c

diff --git a/blockdev.c b/blockdev.c
index 1eb62b6..07fd327 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1193,6 +1193,7 @@
                       enum MirrorSyncMode sync,
                       bool has_mode, enum NewImageMode mode,
                       bool has_speed, int64_t speed,
+                      bool has_granularity, uint32_t granularity,
                       bool has_on_source_error, BlockdevOnError on_source_error,
                       bool has_on_target_error, BlockdevOnError on_target_error,
                       Error **errp)
@@ -1218,6 +1219,17 @@
     if (!has_mode) {
         mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
     }
+    if (!has_granularity) {
+        granularity = 0;
+    }
+    if (granularity != 0 && (granularity < 512 || granularity > 1048576 * 64)) {
+        error_set(errp, QERR_INVALID_PARAMETER, device);
+        return;
+    }
+    if (granularity & (granularity - 1)) {
+        error_set(errp, QERR_INVALID_PARAMETER, device);
+        return;
+    }
 
     bs = bdrv_find(device);
     if (!bs) {
@@ -1299,7 +1311,8 @@
         return;
     }
 
-    mirror_start(bs, target_bs, speed, sync, on_source_error, on_target_error,
+    mirror_start(bs, target_bs, speed, granularity, sync,
+                 on_source_error, on_target_error,
                  block_job_cb, bs, &local_err);
     if (local_err != NULL) {
         bdrv_delete(target_bs);