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block: resize backing image during active layer commit, if needed

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If the top image to commit is the active layer, and also larger than
the base image, then an I/O error will likely be returned during
block-commit.

For instance, if we have a base image with a virtual size 10G, and a
active layer image of size 20G, then committing the snapshot via
'block-commit' will likely fail.

This will automatically attempt to resize the base image, if the
active layer image to be committed is larger.

Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Jeff Cody 2014-01-24 09:02:36 -05:00 committed by Kevin Wolf
parent 72706ea4cd
commit 4da8358596
1 changed files with 38 additions and 0 deletions
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38
block/mirror.c
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@ -631,11 +631,49 @@ void commit_active_start(BlockDriverState *bs, BlockDriverState *base,
BlockDriverCompletionFunc *cb,
void *opaque, Error **errp)
{
int64_t length, base_length;
int orig_base_flags;
orig_base_flags = bdrv_get_flags(base);
if (bdrv_reopen(base, bs->open_flags, errp)) {
return;
}
length = bdrv_getlength(bs);
if (length < 0) {
error_setg(errp, "Unable to determine length of %s", bs->filename);
goto error_restore_flags;
}
base_length = bdrv_getlength(base);
if (base_length < 0) {
error_setg(errp, "Unable to determine length of %s", base->filename);
goto error_restore_flags;
}
if (length > base_length) {
if (bdrv_truncate(base, length) < 0) {
error_setg(errp, "Top image %s is larger than base image %s, and "
"resize of base image failed",
bs->filename, base->filename);
goto error_restore_flags;
}
}
bdrv_ref(base);
mirror_start_job(bs, base, speed, 0, 0,
on_error, on_error, cb, opaque, errp,
&commit_active_job_driver, false, base);
if (error_is_set(errp)) {
goto error_restore_flags;
}
return;
error_restore_flags:
/* ignore error and errp for bdrv_reopen, because we want to propagate
* the original error */
bdrv_reopen(base, orig_base_flags, NULL);
return;
}