Merge tag 'for-6.12-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "A few more one-liners that fix some user visible problems:

   - use correct range when clearing qgroup reservations after COW

   - properly reset freed delayed ref list head

   - fix ro/rw subvolume mounts to be backward compatible with old and
     new mount API"

* tag 'for-6.12-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fix the length of reserved qgroup to free
  btrfs: reinitialize delayed ref list after deleting it from the list
  btrfs: fix per-subvolume RO/RW flags with new mount API

Author: torvalds

fs/btrfs/delayed-ref.c

@@ -649,7 +649,7 @@ static bool insert_delayed_ref(struct btrfs_trans_handle *trans,
 					      &href->ref_add_list);
 			else if (ref->action == BTRFS_DROP_DELAYED_REF) {
 				ASSERT(!list_empty(&exist->add_list));
-				list_del(&exist->add_list);
+				list_del_init(&exist->add_list);
 			} else {
 				ASSERT(0);
 			}

fs/btrfs/inode.c

@@ -1618,7 +1618,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
 		clear_bits |= EXTENT_CLEAR_DATA_RESV;
 		extent_clear_unlock_delalloc(inode, start, end, locked_folio,
 					     &cached, clear_bits, page_ops);
-		btrfs_qgroup_free_data(inode, NULL, start, cur_alloc_size, NULL);
+		btrfs_qgroup_free_data(inode, NULL, start, end - start + 1, NULL);
 	}
 	return ret;
 }

fs/btrfs/super.c

@@ -1979,25 +1979,10 @@ static int btrfs_get_tree_super(struct fs_context *fc)
  *     fsconfig(FSCONFIG_SET_FLAG, "ro"). This option is seen by the filesystem
  *     in fc->sb_flags.
  *
- * This disambiguation has rather positive consequences.  Mounting a subvolume
- * ro will not also turn the superblock ro. Only the mount for the subvolume
- * will become ro.
- *
- * So, if the superblock creation request comes from the new mount API the
- * caller must have explicitly done:
- *
- *      fsconfig(FSCONFIG_SET_FLAG, "ro")
- *      fsmount/mount_setattr(MOUNT_ATTR_RDONLY)
- *
- * IOW, at some point the caller must have explicitly turned the whole
- * superblock ro and we shouldn't just undo it like we did for the old mount
- * API. In any case, it lets us avoid the hack in the new mount API.
- *
- * Consequently, the remounting hack must only be used for requests originating
- * from the old mount API and should be marked for full deprecation so it can be
- * turned off in a couple of years.
- *
- * The new mount API has no reason to support this hack.
+ * But, currently the util-linux mount command already utilizes the new mount
+ * API and is still setting fsconfig(FSCONFIG_SET_FLAG, "ro") no matter if it's
+ * btrfs or not, setting the whole super block RO.  To make per-subvolume mounting
+ * work with different options work we need to keep backward compatibility.
  */
 static struct vfsmount *btrfs_reconfigure_for_mount(struct fs_context *fc)
 {
@@ -2019,7 +2004,7 @@ static struct vfsmount *btrfs_reconfigure_for_mount(struct fs_context *fc)
 	if (IS_ERR(mnt))
 		return mnt;
 
-	if (!fc->oldapi || !ro2rw)
+	if (!ro2rw)
 		return mnt;
 
 	/* We need to convert to rw, call reconfigure. */