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qemu-img: Empty image after commit

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After the top image has been committed, it should be emptied unless
specified otherwise.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 1414159063-25977-10-git-send-email-mreitz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Max Reitz 2014-10-24 15:57:38 +02:00 committed by Stefan Hajnoczi
parent d4a3238af5
commit 9a86fe4895
3 changed files with 38 additions and 6 deletions
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4
qemu-img-cmds.hx
View file

@ -22,9 +22,9 @@ STEXI
ETEXI
DEF("commit", img_commit,
"commit [-q] [-f fmt] [-t cache] filename")
"commit [-q] [-f fmt] [-t cache] [-d] filename")
STEXI
@item commit [-q] [-f @var{fmt}] [-t @var{cache}] @var{filename}
@item commit [-q] [-f @var{fmt}] [-t @var{cache}] [-d] @var{filename}
ETEXI
DEF("compare", img_compare,

34
qemu-img.c
View file

@ -757,14 +757,14 @@ static int img_commit(int argc, char **argv)
const char *filename, *fmt, *cache;
BlockBackend *blk;
BlockDriverState *bs, *base_bs;
bool quiet = false;
bool quiet = false, drop = false;
Error *local_err = NULL;
CommonBlockJobCBInfo cbi;
fmt = NULL;
cache = BDRV_DEFAULT_CACHE;
for(;;) {
c = getopt(argc, argv, "f:ht:q");
c = getopt(argc, argv, "f:ht:dq");
if (c == -1) {
break;
}
@ -779,6 +779,9 @@ static int img_commit(int argc, char **argv)
case 't':
cache = optarg;
break;
case 'd':
drop = true;
break;
case 'q':
quiet = true;
break;
@ -789,7 +792,7 @@ static int img_commit(int argc, char **argv)
}
filename = argv[optind++];
flags = BDRV_O_RDWR;
flags = BDRV_O_RDWR | BDRV_O_UNMAP;
ret = bdrv_parse_cache_flags(cache, &flags);
if (ret < 0) {
error_report("Invalid cache option: %s", cache);
@ -822,7 +825,32 @@ static int img_commit(int argc, char **argv)
goto done;
}
/* The block job will swap base_bs and bs (which is not what we really want
* here, but okay) and unref base_bs (after the swap, i.e., the old top
* image). In order to still be able to empty that top image afterwards,
* increment the reference counter here preemptively. */
if (!drop) {
bdrv_ref(base_bs);
}
run_block_job(bs->job, &local_err);
if (local_err) {
goto unref_backing;
}
if (!drop && base_bs->drv->bdrv_make_empty) {
ret = base_bs->drv->bdrv_make_empty(base_bs);
if (ret) {
error_setg_errno(&local_err, -ret, "Could not empty %s",
filename);
goto unref_backing;
}
}
unref_backing:
if (!drop) {
bdrv_unref(base_bs);
}
done:
blk_unref(blk);

6
qemu-img.texi
View file

@ -167,7 +167,7 @@ this case. @var{backing_file} will never be modified unless you use the
The size can also be specified using the @var{size} option with @code{-o},
it doesn't need to be specified separately in this case.
@item commit [-f @var{fmt}] [-t @var{cache}] @var{filename}
@item commit [-f @var{fmt}] [-t @var{cache}] [-d] @var{filename}
Commit the changes recorded in @var{filename} in its base image or backing file.
If the backing file is smaller than the snapshot, then the backing file will be
@ -176,6 +176,10 @@ the backing file, the backing file will not be truncated. If you want the
backing file to match the size of the smaller snapshot, you can safely truncate
it yourself once the commit operation successfully completes.
The image @var{filename} is emptied after the operation has succeeded. If you do
not need @var{filename} afterwards and intend to drop it, you may skip emptying
@var{filename} by specifying the @code{-d} flag.
@item compare [-f @var{fmt}] [-F @var{fmt}] [-T @var{src_cache}] [-p] [-s] [-q] @var{filename1} @var{filename2}
Check if two images have the same content. You can compare images with