block/dirty-bitmap: add readonly field to BdrvDirtyBitmap

It will be needed in following commits for persistent bitmaps.
If bitmap is loaded from read-only storage (and we can't mark it
"in use" in this storage) corresponding BdrvDirtyBitmap should be
read-only.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20170628120530.31251-11-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/block/io.c b/block/io.c
index 23170a57ee..b413727524 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1315,6 +1315,10 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child,
     uint64_t bytes_remaining = bytes;
     int max_transfer;
 
+    if (bdrv_has_readonly_bitmaps(bs)) {
+        return -EPERM;
+    }
+
     assert(is_power_of_2(align));
     assert((offset & (align - 1)) == 0);
     assert((bytes & (align - 1)) == 0);
@@ -2287,6 +2291,10 @@ int coroutine_fn bdrv_co_pdiscard(BlockDriverState *bs, int64_t offset,
         return -ENOMEDIUM;
     }
 
+    if (bdrv_has_readonly_bitmaps(bs)) {
+        return -EPERM;
+    }
+
     ret = bdrv_check_byte_request(bs, offset, bytes);
     if (ret < 0) {
         return ret;