Currently, if an image file is logically larger than its backing file,
committing it via 'qemu-img commit' will fail.
For instance, if we have a base image with a virtual size 10G, and a
snapshot image of size 20G, then committing the snapshot offline with
'qemu-img commit' will likely fail.
This will automatically attempt to resize the base image, if the
snapshot image to be committed is larger.
Signed-off-by: Jeff Cody <jc...@redhat.com>
Reviewed-by: Fam Zheng <f...@redhat.com>
Reviewed-by: Eric Blake <ebl...@redhat.com>
Reviewed-by: Benoit Canet <ben...@irqsave.net>
---
block.c | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)
diff --git a/block.c b/block.c
index 64e7d22..dea7591 100644
--- a/block.c
+++ b/block.c
@@ -1876,10 +1876,10 @@ int bdrv_check(BlockDriverState *bs, BdrvCheckResult
*res, BdrvCheckMode fix)
int bdrv_commit(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
- int64_t sector, total_sectors;
+ int64_t sector, total_sectors, length, backing_length;
int n, ro, open_flags;
int ret = 0;
- uint8_t *buf;
+ uint8_t *buf = NULL;
char filename[PATH_MAX];
if (!drv)
@@ -1904,7 +1904,24 @@ int bdrv_commit(BlockDriverState *bs)
}
}
- total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
+ length = bdrv_getlength(bs);
+ backing_length = bdrv_getlength(bs->backing_hd);
+
+ if (length < 0 || backing_length < 0) {
+ goto ro_cleanup;
+ }
+
+ /* If our top snapshot is larger than the backing file image,
+ * grow the backing file image if possible. If not possible,
+ * we must return an error */
+ if (length > backing_length) {
+ ret = bdrv_truncate(bs->backing_hd, length);
+ if (ret < 0) {
+ goto ro_cleanup;
+ }
+ }
+
+ total_sectors = length >> BDRV_SECTOR_BITS;
buf = g_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE);
for (sector = 0; sector < total_sectors; sector += n) {
--
1.8.3.1
