[Qemu-devel] [PATCH 12/12] block/backup: loosen restriction on readonly bitmaps

From: John Snow <jsnow@redhat.com>
To: qemu-devel@nongnu.org, qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <fam@euphon.net>,
	vsementsov@virtuozzo.com, Wen Congyang <wencongyang2@huawei.com>,
	Xie Changlong <xiechanglong.d@gmail.com>,
	Markus Armbruster <armbru@redhat.com>,
	Max Reitz <mreitz@redhat.com>, John Snow <jsnow@redhat.com>
Subject: [Qemu-devel] [PATCH 12/12] block/backup: loosen restriction on readonly bitmaps
Date: Wed, 19 Jun 2019 21:03:56 -0400	[thread overview]
Message-ID: <20190620010356.19164-13-jsnow@redhat.com> (raw)
In-Reply-To: <20190620010356.19164-1-jsnow@redhat.com>

With the "never" sync policy, we actually can utilize readonly bitmaps
now. Loosen the check at the QMP level, and tighten it based on
provided arguments down at the job creation level instead.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 block/backup.c | 6 ++++++
 blockdev.c     | 4 ++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index beb2078696..ead9a049e2 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -614,6 +614,12 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
             return NULL;
         }
 
+        /* If we need to write to this bitmap, check that we can: */
+        if (bitmap_mode != BITMAP_SYNC_MODE_NEVER &&
+            bdrv_dirty_bitmap_check(sync_bitmap, BDRV_BITMAP_DEFAULT, errp)) {
+            return NULL;
+        }
+
         /* Create a new bitmap, and freeze/disable this one. */
         if (bdrv_dirty_bitmap_create_successor(bs, sync_bitmap, errp) < 0) {
             return NULL;
diff --git a/blockdev.c b/blockdev.c
index 7abbd6bbf2..173a6b85c6 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3560,7 +3560,7 @@ static BlockJob *do_drive_backup(DriveBackup *backup, JobTxn *txn,
             error_setg(errp, "Bitmap '%s' could not be found", backup->bitmap);
             goto unref;
         }
-        if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_DEFAULT, errp)) {
+        if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_ALLOW_RO, errp)) {
             goto unref;
         }
     }
@@ -3667,7 +3667,7 @@ BlockJob *do_blockdev_backup(BlockdevBackup *backup, JobTxn *txn,
             error_setg(errp, "Bitmap '%s' could not be found", backup->bitmap);
             goto out;
         }
-        if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_DEFAULT, errp)) {
+        if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_ALLOW_RO, errp)) {
             goto out;
         }
     }
-- 
2.21.0


