block: Allow empty integrity profile

Allow a block device to allocate and register an integrity profile
without providing a template.  This allows DM to preallocate a profile
to avoid deadlocks during table reconfiguration.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 14 insertions, 11 deletions

diff --git a/block/blk-integrity.c b/block/blk-integrity.c
index 61a8e2f8fdd0..91fa8e06b6a5 100644
--- a/block/blk-integrity.c
+++ b/block/blk-integrity.c
@@ -309,24 +309,24 @@ static struct kobj_type integrity_ktype = {
 /**
  * blk_integrity_register - Register a gendisk as being integrity-capable
  * @disk:       struct gendisk pointer to make integrity-aware
- * @template:   integrity profile
+ * @template:   optional integrity profile to register
  *
  * Description: When a device needs to advertise itself as being able
  * to send/receive integrity metadata it must use this function to
  * register the capability with the block layer.  The template is a
  * blk_integrity struct with values appropriate for the underlying
- * hardware.  See Documentation/block/data-integrity.txt.
+ * hardware.  If template is NULL the new profile is allocated but
+ * not filled out. See Documentation/block/data-integrity.txt.
  */
 int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
 {
         struct blk_integrity *bi;
 
         BUG_ON(disk == NULL);
-        BUG_ON(template == NULL);
 
         if (disk->integrity == NULL) {
                 bi = kmem_cache_alloc(integrity_cachep,
-                                                GFP_KERNEL | __GFP_ZERO);
+                                      GFP_KERNEL | __GFP_ZERO);
                 if (!bi)
                         return -1;
 
@@ -346,13 +346,16 @@ int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
                 bi = disk->integrity;
 
         /* Use the provided profile as template */
-        bi->name = template->name;
-        bi->generate_fn = template->generate_fn;
-        bi->verify_fn = template->verify_fn;
-        bi->tuple_size = template->tuple_size;
-        bi->set_tag_fn = template->set_tag_fn;
-        bi->get_tag_fn = template->get_tag_fn;
-        bi->tag_size = template->tag_size;
+        if (template != NULL) {
+                bi->name = template->name;
+                bi->generate_fn = template->generate_fn;
+                bi->verify_fn = template->verify_fn;
+                bi->tuple_size = template->tuple_size;
+                bi->set_tag_fn = template->set_tag_fn;
+                bi->get_tag_fn = template->get_tag_fn;
+                bi->tag_size = template->tag_size;
+        } else
+                bi->name = "unsupported";
 
         return 0;
 }