qcow2: Store data file name in the image
Rather than requiring that the external data file node is passed
explicitly when creating the qcow2 node, store the filename in the
designated header extension during .bdrv_create and read it from there
as a default during .bdrv_open.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/qcow2.c b/block/qcow2.c
index c20141b..f32ddda 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -398,6 +398,21 @@
#endif
break;
+ case QCOW2_EXT_MAGIC_DATA_FILE:
+ {
+ s->image_data_file = g_malloc0(ext.len + 1);
+ ret = bdrv_pread(bs->file, offset, s->image_data_file, ext.len);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret,
+ "ERROR: Could not read data file name");
+ return ret;
+ }
+#ifdef DEBUG_EXT
+ printf("Qcow2: Got external data file %s\n", s->image_data_file);
+#endif
+ break;
+ }
+
default:
/* unknown magic - save it in case we need to rewrite the header */
/* If you add a new feature, make sure to also update the fast
@@ -1463,6 +1478,15 @@
}
if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) {
+ if (!s->data_file && s->image_data_file) {
+ s->data_file = bdrv_open_child(s->image_data_file, options,
+ "data-file", bs, &child_file,
+ false, errp);
+ if (!s->data_file) {
+ ret = -EINVAL;
+ goto fail;
+ }
+ }
if (!s->data_file) {
error_setg(errp, "'data-file' is required for this image");
ret = -EINVAL;
@@ -1650,6 +1674,7 @@
return ret;
fail:
+ g_free(s->image_data_file);
if (has_data_file(bs)) {
bdrv_unref_child(bs, s->data_file);
}
@@ -2269,6 +2294,7 @@
g_free(s->unknown_header_fields);
cleanup_unknown_header_ext(bs);
+ g_free(s->image_data_file);
g_free(s->image_backing_file);
g_free(s->image_backing_format);
@@ -2445,6 +2471,19 @@
buflen -= ret;
}
+ /* External data file header extension */
+ if (has_data_file(bs) && s->image_data_file) {
+ ret = header_ext_add(buf, QCOW2_EXT_MAGIC_DATA_FILE,
+ s->image_data_file, strlen(s->image_data_file),
+ buflen);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ buf += ret;
+ buflen -= ret;
+ }
+
/* Full disk encryption header pointer extension */
if (s->crypto_header.offset != 0) {
s->crypto_header.offset = cpu_to_be64(s->crypto_header.offset);
@@ -3086,6 +3125,12 @@
abort();
}
+ /* Set the external data file if necessary */
+ if (data_bs) {
+ BDRVQcow2State *s = blk_bs(blk)->opaque;
+ s->image_data_file = g_strdup(data_bs->filename);
+ }
+
/* Create a full header (including things like feature table) */
ret = qcow2_update_header(blk_bs(blk));
if (ret < 0) {
@@ -3165,6 +3210,7 @@
QDict *qdict;
Visitor *v;
BlockDriverState *bs = NULL;
+ BlockDriverState *data_bs = NULL;
Error *local_err = NULL;
const char *val;
int ret;
@@ -3228,6 +3274,26 @@
goto finish;
}
+ /* Create and open an external data file (protocol layer) */
+ val = qdict_get_try_str(qdict, BLOCK_OPT_DATA_FILE);
+ if (val) {
+ ret = bdrv_create_file(val, opts, errp);
+ if (ret < 0) {
+ goto finish;
+ }
+
+ data_bs = bdrv_open(val, NULL, NULL,
+ BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
+ errp);
+ if (data_bs == NULL) {
+ ret = -EIO;
+ goto finish;
+ }
+
+ qdict_del(qdict, BLOCK_OPT_DATA_FILE);
+ qdict_put_str(qdict, "data-file", data_bs->node_name);
+ }
+
/* Set 'driver' and 'node' options */
qdict_put_str(qdict, "driver", "qcow2");
qdict_put_str(qdict, "file", bs->node_name);
@@ -3262,6 +3328,7 @@
finish:
qobject_unref(qdict);
bdrv_unref(bs);
+ bdrv_unref(data_bs);
qapi_free_BlockdevCreateOptions(create_options);
return ret;
}
@@ -4552,6 +4619,8 @@
.refcount_bits = s->refcount_bits,
.has_bitmaps = !!bitmaps,
.bitmaps = bitmaps,
+ .has_data_file = !!s->image_data_file,
+ .data_file = g_strdup(s->image_data_file),
};
} else {
/* if this assertion fails, this probably means a new version was
@@ -4754,7 +4823,7 @@
BDRVQcow2State *s = bs->opaque;
int old_version = s->qcow_version, new_version = old_version;
uint64_t new_size = 0;
- const char *backing_file = NULL, *backing_format = NULL;
+ const char *backing_file = NULL, *backing_format = NULL, *data_file = NULL;
bool lazy_refcounts = s->use_lazy_refcounts;
const char *compat = NULL;
uint64_t cluster_size = s->cluster_size;
@@ -4836,6 +4905,13 @@
"may not exceed 64 bits");
return -EINVAL;
}
+ } else if (!strcmp(desc->name, BLOCK_OPT_DATA_FILE)) {
+ data_file = qemu_opt_get(opts, BLOCK_OPT_DATA_FILE);
+ if (data_file && !has_data_file(bs)) {
+ error_setg(errp, "data-file can only be set for images that "
+ "use an external data file");
+ return -EINVAL;
+ }
} else {
/* if this point is reached, this probably means a new option was
* added without having it covered here */
@@ -4882,6 +4958,17 @@
}
}
+ if (data_file) {
+ g_free(s->image_data_file);
+ s->image_data_file = *data_file ? g_strdup(data_file) : NULL;
+ }
+
+ ret = qcow2_update_header(bs);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "Failed to update the image header");
+ return ret;
+ }
+
if (backing_file || backing_format) {
ret = qcow2_change_backing_file(bs,
backing_file ?: s->image_backing_file,
@@ -5030,6 +5117,11 @@
.help = "Image format of the base image"
},
{
+ .name = BLOCK_OPT_DATA_FILE,
+ .type = QEMU_OPT_STRING,
+ .help = "File name of an external data file"
+ },
+ {
.name = BLOCK_OPT_ENCRYPT,
.type = QEMU_OPT_BOOL,
.help = "Encrypt the image with format 'aes'. (Deprecated "
