[PATCH] block: allocate aligned write buffer for 'truncate -m full'

[Andrey Drobyshev]

In case we're truncating an image opened with O_DIRECT, we might get
-EINVAL on write with unaligned buffer.  In particular, when running
iotests/298 with '-nocache' we get:

qemu-io: Failed to resize underlying file: Could not write zeros for
preallocation: Invalid argument

Let's just allocate the buffer using qemu_blockalign0() instead.

Signed-off-by: Andrey Drobyshev <andrey.drobys...@virtuozzo.com>
---
 block/file-posix.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index b862406c71..cee8de510b 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -2354,7 +2354,7 @@ static int handle_aiocb_truncate(void *opaque)
             goto out;
         }
 
-        buf = g_malloc0(65536);
+        buf = qemu_blockalign0(aiocb->bs, 65536);
 
         seek_result = lseek(fd, current_length, SEEK_SET);
         if (seek_result < 0) {
@@ -2413,7 +2413,7 @@ out:
         }
     }
 
-    g_free(buf);
+    qemu_vfree(buf);
     return result;
 }
 
-- 
2.39.3