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qemu-img: Check for backing image if specified during create

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Or, rather, force the open of a backing image if one was specified
for creation. Using a similar -unsafe option as rebase, allow qemu-img
to ignore the backing file validation if possible.

It may not always be possible, as in the existing case when a filesize
for the new image was not specified.

This is accomplished by shifting around the conditionals in
bdrv_img_create, such that a backing file is always opened unless we
provide BDRV_O_NO_BACKING. qemu-img is adjusted to pass this new flag
when -u is provided to create.

Sorry for the heinous looking diffstat, but it's mostly whitespace.

Inspired by: https://bugzilla.redhat.com/show_bug.cgi?id=1213786

Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
John Snow 2017-07-17 20:34:22 -04:00 • committed by Kevin Wolf
parent 2a32c6e82e
commit 6e6e55f5c2
12 changed files with 85 additions and 61 deletions
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98
block.c
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@ -4396,55 +4396,65 @@ void bdrv_img_create(const char *filename, const char *fmt,
backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
// The size for the image must always be specified, with one exception:
// If we are using a backing file, we can obtain the size from there
/* The size for the image must always be specified, unless we have a backing
* file and we have not been forbidden from opening it. */
size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 0);
if (size == -1) {
if (backing_file) {
BlockDriverState *bs;
char *full_backing = g_new0(char, PATH_MAX);
int64_t size;
int back_flags;
QDict *backing_options = NULL;
if (backing_file && !(flags & BDRV_O_NO_BACKING)) {
BlockDriverState *bs;
char *full_backing = g_new0(char, PATH_MAX);
int back_flags;
QDict *backing_options = NULL;
bdrv_get_full_backing_filename_from_filename(filename, backing_file,
full_backing, PATH_MAX,
&local_err);
if (local_err) {
g_free(full_backing);
goto out;
}
/* backing files always opened read-only */
back_flags = flags;
back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
if (backing_fmt) {
backing_options = qdict_new();
qdict_put_str(backing_options, "driver", backing_fmt);
}
bs = bdrv_open(full_backing, NULL, backing_options, back_flags,
&local_err);
bdrv_get_full_backing_filename_from_filename(filename, backing_file,
full_backing, PATH_MAX,
&local_err);
if (local_err) {
g_free(full_backing);
if (!bs) {
goto out;
}
size = bdrv_getlength(bs);
if (size < 0) {
error_setg_errno(errp, -size, "Could not get size of '%s'",
backing_file);
bdrv_unref(bs);
goto out;
}
qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort);
bdrv_unref(bs);
} else {
error_setg(errp, "Image creation needs a size parameter");
goto out;
}
/* backing files always opened read-only */
back_flags = flags;
back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
if (backing_fmt) {
backing_options = qdict_new();
qdict_put_str(backing_options, "driver", backing_fmt);
}
bs = bdrv_open(full_backing, NULL, backing_options, back_flags,
&local_err);
g_free(full_backing);
if (!bs && size != -1) {
/* Couldn't open BS, but we have a size, so it's nonfatal */
warn_reportf_err(local_err,
"Could not verify backing image. "
"This may become an error in future versions.\n");
local_err = NULL;
} else if (!bs) {
/* Couldn't open bs, do not have size */
error_append_hint(&local_err,
"Could not open backing image to determine size.\n");
goto out;
} else {
if (size == -1) {
/* Opened BS, have no size */
size = bdrv_getlength(bs);
if (size < 0) {
error_setg_errno(errp, -size, "Could not get size of '%s'",
backing_file);
bdrv_unref(bs);
goto out;
}
qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort);
}
bdrv_unref(bs);
}
} /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */
if (size == -1) {
error_setg(errp, "Image creation needs a size parameter");
goto out;
}
if (!quiet) {