block: Add error handling to bdrv_invalidate_cache()

If it returns an error, the migrated VM will not be started, but qemu
exits with an error message.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>

block.c

@@ -4781,27 +4781,43 @@ flush_parent:
     return bdrv_co_flush(bs->file);
 }
 
-void bdrv_invalidate_cache(BlockDriverState *bs)
+void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp)
 {
+    Error *local_err = NULL;
+    int ret;
+
     if (!bs->drv)  {
         return;
     }
 
     if (bs->drv->bdrv_invalidate_cache) {
-        bs->drv->bdrv_invalidate_cache(bs);
+        bs->drv->bdrv_invalidate_cache(bs, &local_err);
     } else if (bs->file) {
-        bdrv_invalidate_cache(bs->file);
+        bdrv_invalidate_cache(bs->file, &local_err);
+    }
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
     }
 
-    refresh_total_sectors(bs, bs->total_sectors);
+    ret = refresh_total_sectors(bs, bs->total_sectors);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "Could not refresh total sector count");
+        return;
+    }
 }
 
-void bdrv_invalidate_cache_all(void)
+void bdrv_invalidate_cache_all(Error **errp)
 {
     BlockDriverState *bs;
+    Error *local_err = NULL;
 
     QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
-        bdrv_invalidate_cache(bs);
+        bdrv_invalidate_cache(bs, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
     }
 }
 

block/qcow2.c

@@ -1156,7 +1156,7 @@ static void qcow2_close(BlockDriverState *bs)
     qcow2_free_snapshots(bs);
 }
 
-static void qcow2_invalidate_cache(BlockDriverState *bs)
+static void qcow2_invalidate_cache(BlockDriverState *bs, Error **errp)
 {
     BDRVQcowState *s = bs->opaque;
     int flags = s->flags;
@@ -1164,6 +1164,8 @@ static void qcow2_invalidate_cache(BlockDriverState *bs)
     AES_KEY aes_decrypt_key;
     uint32_t crypt_method = 0;
     QDict *options;
+    Error *local_err = NULL;
+    int ret;
 
     /*
      * Backing files are read-only which makes all of their metadata immutable,
@@ -1178,11 +1180,25 @@ static void qcow2_invalidate_cache(BlockDriverState *bs)
 
     qcow2_close(bs);
 
-    bdrv_invalidate_cache(bs->file);
+    bdrv_invalidate_cache(bs->file, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
 
     memset(s, 0, sizeof(BDRVQcowState));
     options = qdict_clone_shallow(bs->options);
-    qcow2_open(bs, options, flags, NULL);
+
+    ret = qcow2_open(bs, options, flags, &local_err);
+    if (local_err) {
+        error_setg(errp, "Could not reopen qcow2 layer: %s",
+                   error_get_pretty(local_err));
+        error_free(local_err);
+        return;
+    } else if (ret < 0) {
+        error_setg_errno(errp, -ret, "Could not reopen qcow2 layer");
+        return;
+    }
 
     QDECREF(options);
 

block/qed.c

@@ -1558,16 +1558,31 @@ static int bdrv_qed_change_backing_file(BlockDriverState *bs,
     return ret;
 }
 
-static void bdrv_qed_invalidate_cache(BlockDriverState *bs)
+static void bdrv_qed_invalidate_cache(BlockDriverState *bs, Error **errp)
 {
     BDRVQEDState *s = bs->opaque;
+    Error *local_err = NULL;
+    int ret;
 
     bdrv_qed_close(bs);
 
-    bdrv_invalidate_cache(bs->file);
+    bdrv_invalidate_cache(bs->file, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
 
     memset(s, 0, sizeof(BDRVQEDState));
-    bdrv_qed_open(bs, NULL, bs->open_flags, NULL);
+    ret = bdrv_qed_open(bs, NULL, bs->open_flags, &local_err);
+    if (local_err) {
+        error_setg(errp, "Could not reopen qed layer: %s",
+                   error_get_pretty(local_err));
+        error_free(local_err);
+        return;
+    } else if (ret < 0) {
+        error_setg_errno(errp, -ret, "Could not reopen qed layer");
+        return;
+    }
 }
 
 static int bdrv_qed_check(BlockDriverState *bs, BdrvCheckResult *result,

block/quorum.c

@@ -625,13 +625,18 @@ static int64_t quorum_getlength(BlockDriverState *bs)
     return result;
 }
 
-static void quorum_invalidate_cache(BlockDriverState *bs)
+static void quorum_invalidate_cache(BlockDriverState *bs, Error **errp)
 {
     BDRVQuorumState *s = bs->opaque;
+    Error *local_err = NULL;
     int i;
 
     for (i = 0; i < s->num_children; i++) {
-        bdrv_invalidate_cache(s->bs[i]);
+        bdrv_invalidate_cache(s->bs[i], &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
     }
 }
 

include/block/block.h

@@ -329,8 +329,8 @@ BlockDriverAIOCB *bdrv_aio_ioctl(BlockDriverState *bs,
         BlockDriverCompletionFunc *cb, void *opaque);
 
 /* Invalidate any cached metadata used by image formats */
-void bdrv_invalidate_cache(BlockDriverState *bs);
+void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp);
-void bdrv_invalidate_cache_all(void);
+void bdrv_invalidate_cache_all(Error **errp);
 
 void bdrv_clear_incoming_migration_all(void);
 

include/block/block_int.h

@@ -153,7 +153,7 @@ struct BlockDriver {
     /*
      * Invalidate any cached meta-data.
      */
-    void (*bdrv_invalidate_cache)(BlockDriverState *bs);
+    void (*bdrv_invalidate_cache)(BlockDriverState *bs, Error **errp);
 
     /*
      * Flushes all data that was already written to the OS all the way down to

migration.c

@@ -101,6 +101,7 @@ void qemu_start_incoming_migration(const char *uri, Error **errp)
 static void process_incoming_migration_co(void *opaque)
 {
     QEMUFile *f = opaque;
+    Error *local_err = NULL;
     int ret;
 
     ret = qemu_loadvm_state(f);
@@ -115,7 +116,12 @@ static void process_incoming_migration_co(void *opaque)
 
     bdrv_clear_incoming_migration_all();
     /* Make sure all file formats flush their mutable metadata */
-    bdrv_invalidate_cache_all();
+    bdrv_invalidate_cache_all(&local_err);
+    if (local_err) {
+        qerror_report_err(local_err);
+        error_free(local_err);
+        exit(EXIT_FAILURE);
+    }
 
     if (autostart) {
         vm_start();