[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH v2] qcow2: Flush image after creation
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH v2] qcow2: Flush image after creation |
Date: |
Thu, 24 Oct 2013 20:35:06 +0200 |
Opening the qcow2 image with BDRV_O_NO_FLUSH prevents any flushes during
the image creation. This means that the image has not yet been flushed
to disk when qemu-img create exits. This flush is delayed until the next
operation on the image involving opening it without BDRV_O_NO_FLUSH and
closing (or directly flushing) it. For large images and/or images with a
small cluster size and preallocated metadata, this flush may take a
significant amount of time and may occur unexpectedly.
Reopening the image without BDRV_O_NO_FLUSH right before the end of
qcow2_create2() results in hoisting the potentially costly flush into
the image creation, which is expected to take some time (whereas
successive image operations may be not).
Signed-off-by: Max Reitz <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
---
v2:
- implemented Kevin's remarks:
- left ret = 0; in the code
- added goto out; in error handling of bdrv_open
- implemented Eric's remarks:
- changed indentation of bdrv_open arguments
- s/preponing/hoisting/ in the commit message
---
block/qcow2.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/block/qcow2.c b/block/qcow2.c
index 01269f9..6e5d98d 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1584,6 +1584,16 @@ static int qcow2_create2(const char *filename, int64_t
total_size,
}
}
+ bdrv_close(bs);
+
+ /* Reopen the image without BDRV_O_NO_FLUSH to flush it before returning */
+ ret = bdrv_open(bs, filename, NULL,
+ BDRV_O_RDWR | BDRV_O_CACHE_WB, drv, &local_err);
+ if (error_is_set(&local_err)) {
+ error_propagate(errp, local_err);
+ goto out;
+ }
+
ret = 0;
out:
bdrv_unref(bs);
--
1.8.3.1
- [Qemu-devel] [PATCH v2] qcow2: Flush image after creation,
Max Reitz <=