block/migration: Disable cache invalidate for incoming migration

When migrated using libvirt with "--copy-storage-all", at the end of
migration there is race between NBD mirroring task trying to do flush
and migration completion, both end up invalidating cache. Since qcow2
driver does not handle this situation very well, random crashes happen.

This disables the BDRV_O_INCOMING flag for the block device being migrated
once the cache has been invalidated.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
--

fixed parens by hand
Signed-off-by: Juan Quintela <quintela@redhat.com>

diff --git a/block.c b/block.c
index d3aebeb050b5467b0a7fdd7d377ab1a6c083eba3..27533f3a8125508a5506f2f189318719a11735f2 100644 (file)
--- a/block.c
+++ b/block.c
@@ -5043,6 +5043,11 @@ void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp)
         return;
     }
 
+    if (!(bs->open_flags & BDRV_O_INCOMING)) {
+        return;
+    }
+    bs->open_flags &= ~BDRV_O_INCOMING;
+
     if (bs->drv->bdrv_invalidate_cache) {
         bs->drv->bdrv_invalidate_cache(bs, &local_err);
     } else if (bs->file) {
@@ -5078,19 +5083,6 @@ void bdrv_invalidate_cache_all(Error **errp)
     }
 }
 
-void bdrv_clear_incoming_migration_all(void)
-{
-    BlockDriverState *bs;
-
-    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
-        AioContext *aio_context = bdrv_get_aio_context(bs);
-
-        aio_context_acquire(aio_context);
-        bs->open_flags = bs->open_flags & ~(BDRV_O_INCOMING);
-        aio_context_release(aio_context);
-    }
-}
-
 int bdrv_flush(BlockDriverState *bs)
 {
     Coroutine *co;

diff --git a/migration.c b/migration.c
index 8d675b31a1792a0e0ed174b1844354fe9efdcd8c..c49a05a16595993ca255eb7b1b84519b31e5fa2c 100644 (file)
--- a/migration.c
+++ b/migration.c
@@ -103,7 +103,6 @@ static void process_incoming_migration_co(void *opaque)
     }
     qemu_announce_self();
 
-    bdrv_clear_incoming_migration_all();
     /* Make sure all file formats flush their mutable metadata */
     bdrv_invalidate_cache_all(&local_err);
     if (local_err) {

diff --git a/nbd.c b/nbd.c
index e9b539be58307b880fec09463a97d9ab94c505bb..a7bce451178104ba126b58651b0dbe557802c8a8 100644 (file)
--- a/nbd.c
+++ b/nbd.c
@@ -972,6 +972,12 @@ NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset,
     exp->ctx = bdrv_get_aio_context(bs);
     bdrv_ref(bs);
     bdrv_add_aio_context_notifier(bs, bs_aio_attached, bs_aio_detach, exp);
+    /*
+     * NBD exports are used for non-shared storage migration.  Make sure
+     * that BDRV_O_INCOMING is cleared and the image is ready for write
+     * access since the export could be available before migration handover.
+     */
+    bdrv_invalidate_cache(bs, NULL);
     return exp;
 }