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>

1 files changed, 26 insertions, 8 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 61ce29d268a6..92867f3e945c 100644
--- 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;