rbd: dynamically allocate object prefix

There is no need to impose a small limit the length of the object
prefix recorded for an rbd image in a struct rbd_image_header.
Remove the limitation by allocating space for the object prefix
dynamically.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 61ce29d..92867f3 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -77,7 +77,7 @@
  */
 struct rbd_image_header {
        u64 image_size;
-       char object_prefix[32];
+       char *object_prefix;
        __u8 obj_order;
        __u8 crypt_type;
        __u8 comp_type;
@@ -517,8 +517,15 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
                header->snap_names = NULL;
                header->snap_sizes = NULL;
        }
+
+       header->object_prefix = kmalloc(sizeof (ondisk->block_name) + 1,
+                                       gfp_flags);
+       if (!header->object_prefix)
+               goto err_sizes;
+
        memcpy(header->object_prefix, ondisk->block_name,
               sizeof(ondisk->block_name));
+       header->object_prefix[sizeof (ondisk->block_name)] = '\0';
 
        header->image_size = le64_to_cpu(ondisk->image_size);
        header->obj_order = ondisk->options.order;
@@ -545,6 +552,8 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
 
        return 0;
 
+err_sizes:
+       kfree(header->snap_sizes);
 err_names:
        kfree(header->snap_names);
 err_snapc:
@@ -610,9 +619,10 @@ done:
 
 static void rbd_header_free(struct rbd_image_header *header)
 {
-       kfree(header->snapc);
-       kfree(header->snap_names);
+       kfree(header->object_prefix);
        kfree(header->snap_sizes);
+       kfree(header->snap_names);
+       kfree(header->snapc);
 }
 
 /*
@@ -1710,15 +1720,20 @@ static int __rbd_refresh_header(struct rbd_device *rbd_dev)
                   if head moves */
                follow_seq = 1;
 
-       kfree(rbd_dev->header.snapc);
-       kfree(rbd_dev->header.snap_names);
+       /* rbd_dev->header.object_prefix shouldn't change */
        kfree(rbd_dev->header.snap_sizes);
+       kfree(rbd_dev->header.snap_names);
+       kfree(rbd_dev->header.snapc);
 
        rbd_dev->header.total_snaps = h.total_snaps;
        rbd_dev->header.snapc = h.snapc;
        rbd_dev->header.snap_names = h.snap_names;
        rbd_dev->header.snap_names_len = h.snap_names_len;
        rbd_dev->header.snap_sizes = h.snap_sizes;
+       /* Free the extra copy of the object prefix */
+       WARN_ON(strcmp(rbd_dev->header.object_prefix, h.object_prefix));
+       kfree(h.object_prefix);
+
        if (follow_seq)
                rbd_dev->header.snapc->seq = rbd_dev->header.snapc->snaps[0];
        else
@@ -2361,10 +2376,11 @@ static int rbd_add_parse_args(struct rbd_device *rbd_dev,
        if (!rbd_dev->pool_name)
                return -ENOMEM;
 
-       ret = -EINVAL;
        len = copy_token(&buf, rbd_dev->obj, sizeof (rbd_dev->obj));
-       if (!len || len >= sizeof (rbd_dev->obj))
+       if (!len || len >= sizeof (rbd_dev->obj)) {
+               ret = -EINVAL;
                goto out_err;
+       }
 
        /* We have the object length in hand, save it. */
 
@@ -2382,8 +2398,10 @@ static int rbd_add_parse_args(struct rbd_device *rbd_dev,
        if (!len)
                memcpy(rbd_dev->snap_name, RBD_SNAP_HEAD_NAME,
                        sizeof (RBD_SNAP_HEAD_NAME));
-       else if (len >= sizeof (rbd_dev->snap_name))
+       else if (len >= sizeof (rbd_dev->snap_name)) {
+               ret = -EINVAL;
                goto out_err;
+       }
 
        return 0;