diff mbox series

[for-4.0,v2,2/3] block: freeze the backing chain earlier in stream_start()

Message ID 9ddb290573f04bdcf98985e569001efb5d19a9de.1553789986.git.berto@igalia.com
State New
Headers show
Series freeze the backing chain earlier in stream_start() | expand

Commit Message

Alberto Garcia March 28, 2019, 4:25 p.m. UTC 
Commit 6585493369819a48d34a86d57ec6b97cb5cd9bc0 added code to freeze
the backing chain from 'top' to 'base' for the duration of the
block-stream job.

The problem is that the freezing happens too late in stream_start():
during the bdrv_reopen_set_read_only() call earlier in that function
another job can jump in and remove the base image. If that happens we
have an invalid chain and QEMU crashes.

This patch puts the bdrv_freeze_backing_chain() call at the beginning
of the function.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/stream.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/block/stream.c b/block/stream.c
index 6253c86fae..bfaebb861a 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -238,11 +238,16 @@  void stream_start(const char *job_id, BlockDriverState *bs,
     BlockDriverState *iter;
     bool bs_read_only;
 
+    if (bdrv_freeze_backing_chain(bs, base, errp) < 0) {
+        return;
+    }
+
     /* Make sure that the image is opened in read-write mode */
     bs_read_only = bdrv_is_read_only(bs);
     if (bs_read_only) {
         if (bdrv_reopen_set_read_only(bs, false, errp) != 0) {
-            return;
+            bs_read_only = false;
+            goto fail;
         }
     }
 
@@ -269,11 +274,6 @@  void stream_start(const char *job_id, BlockDriverState *bs,
                            &error_abort);
     }
 
-    if (bdrv_freeze_backing_chain(bs, base, errp) < 0) {
-        job_early_fail(&s->common.job);
-        goto fail;
-    }
-
     s->base = base;
     s->backing_file_str = g_strdup(backing_file_str);
     s->bs_read_only = bs_read_only;
@@ -288,4 +288,5 @@  fail:
     if (bs_read_only) {
         bdrv_reopen_set_read_only(bs, true, NULL);
     }
+    bdrv_unfreeze_backing_chain(bs, base);
 }