block: Update image size in bdrv_invalidate_cache()

After migration has completed, we call bdrv_invalidate_cache() so that
drivers which cache some data drop their stale copy of the data and
reread it from the image file to get a new version of data that the
source modified while the migration was running.

Reloading metadata from the image file is useless, though, if the size
of the image file stays stale (this is a value that is cached for all
image formats in block.c). Reads from (meta)data after the old EOF
return only zeroes, causing image corruption.

We need to update bs->total_sectors in all layers that could potentially
have changed their size (i.e. backing files are not a concern - if they
are changed, we're in bigger trouble)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/block.c b/block.c
index f1ef4b0109dbededb10b26552670d1fee60579aa..7b306fb62fc1a8a2edb363e20d2addc3bb649298 100644 (file)
--- a/block.c
+++ b/block.c
@@ -4776,9 +4776,17 @@ flush_parent:
 
 void bdrv_invalidate_cache(BlockDriverState *bs)
 {
-    if (bs->drv && bs->drv->bdrv_invalidate_cache) {
+    if (!bs->drv)  {
+        return;
+    }
+
+    if (bs->drv->bdrv_invalidate_cache) {
         bs->drv->bdrv_invalidate_cache(bs);
+    } else if (bs->file) {
+        bdrv_invalidate_cache(bs->file);
     }
+
+    refresh_total_sectors(bs, bs->total_sectors);
 }
 
 void bdrv_invalidate_cache_all(void)

diff --git a/block/qcow2.c b/block/qcow2.c
index cfe80befa05ffd19442313ad252a221de8e331bc..b5b1e8c1b92f61f3ca88eda31a3721877a3bcd25 100644 (file)
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1176,6 +1176,8 @@ static void qcow2_invalidate_cache(BlockDriverState *bs)
 
     qcow2_close(bs);
 
+    bdrv_invalidate_cache(bs->file);
+
     options = qdict_new();
     qdict_put(options, QCOW2_OPT_LAZY_REFCOUNTS,
               qbool_from_int(s->use_lazy_refcounts));

diff --git a/block/qed.c b/block/qed.c
index 8802ad3845bcb7b5fcbc3552f552d0d7115d4735..837accd39b4ab54def1e3a7f469b1f0381dd73b7 100644 (file)
--- a/block/qed.c
+++ b/block/qed.c
@@ -1563,6 +1563,9 @@ static void bdrv_qed_invalidate_cache(BlockDriverState *bs)
     BDRVQEDState *s = bs->opaque;
 
     bdrv_qed_close(bs);
+
+    bdrv_invalidate_cache(bs->file);
+
     memset(s, 0, sizeof(BDRVQEDState));
     bdrv_qed_open(bs, NULL, bs->open_flags, NULL);
 }