[Qemu-devel] [PATCH 2/2] block/rbd: Attempt to parse legacy filenames

[Jeff Cody]

When we converted rbd to get rid of the older key/value-centric
encoding format, we broke compatibility with image files with backing
file strings encoded in the old format.

This leaves a bit of an ugly conundrum, and a hacky solution.

If the initial attempt to parse the "proper" options fails, it assumes
that we may have an older key/value encoded filename.  Fall back to
attempting to parse the filename, and extract the required options from
it.  If that fails, pass along the original error message.

This approach has a potential drawback: if for some reason there are
some options supplied the new way, and some the old way, we may not
catch all the old options if they are not required options (since it
won't cause the initial failure).

Signed-off-by: Jeff Cody <address@hidden>
---
 block/rbd.c | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/block/rbd.c b/block/rbd.c
index a8e79d01d2..bce86b8bde 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -685,7 +685,7 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict 
*options, int flags,
     BlockdevOptionsRbd *opts = NULL;
     const QDictEntry *e;
     Error *local_err = NULL;
-    char *keypairs, *secretid;
+    char *keypairs, *secretid, *filename;
     int r;
 
     keypairs = g_strdup(qdict_get_try_str(options, "=keyvalue-pairs"));
@@ -700,8 +700,32 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict 
*options, int flags,
 
     r = qemu_rbd_convert_options(bs, options, &opts, &local_err);
     if (local_err) {
-        error_propagate(errp, local_err);
-        goto out;
+        /* If the initial attempt to convert and process the options failed,
+         * we may be attempting to open an image file that has the rbd options
+         * specified in the older format consisting of all key/value pairs
+         * encoded in the filename.  Go ahead and attempt to parse the
+         * filename, and see if we can pull out the required options */
+        Error *parse_err = NULL;
+
+        filename = g_strdup(qdict_get_try_str(options, "filename"));
+        qdict_del(options, "filename");
+
+        qemu_rbd_parse_filename(filename, options, NULL);
+
+        g_free(keypairs);
+        keypairs = g_strdup(qdict_get_try_str(options, "=keyvalue-pairs"));
+        if (keypairs) {
+            qdict_del(options, "=keyvalue-pairs");
+        }
+
+        r = qemu_rbd_convert_options(bs, options, &opts, &parse_err);
+        if (parse_err) {
+            /* if the second attempt failed, pass along the original error
+             * message for the current format */
+            error_propagate(errp, local_err);
+            error_free(parse_err);
+            goto out;
+        }
     }
 
     /* Remove the processed options from the QDict (the visitor processes
-- 
2.17.1