From: Kevin Wolf <kwolf@redhat.com>
Date: Wed, 21 May 2014 16:16:21 +0000 (+0200)
Subject: mirror: Handle failure for potentially large allocations
X-Git-Tag: qemu-xen-4.6.0-rc1~264^2~4
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=7504edf477d2bac9cbf53225811ec595abf045e4;p=qemu-upstream-4.6-testing.git

mirror: Handle failure for potentially large allocations

Some code in the block layer makes potentially huge allocations. Failure
is not completely unexpected there, so avoid aborting qemu and handle
out-of-memory situations gracefully.

This patch addresses the allocations in the mirror block job.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
---

diff --git a/block/mirror.c b/block/mirror.c
index c7a655fc5..5e7a166b3 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -367,7 +367,12 @@ static void coroutine_fn mirror_run(void *opaque)
     }
 
     end = s->common.len >> BDRV_SECTOR_BITS;
-    s->buf = qemu_blockalign(bs, s->buf_size);
+    s->buf = qemu_try_blockalign(bs, s->buf_size);
+    if (s->buf == NULL) {
+        ret = -ENOMEM;
+        goto immediate_exit;
+    }
+
     sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS;
     mirror_free_init(s);