btrfs: rename btrfs_add_delalloc_inodes() to singular form

The function btrfs_add_delalloc_inodes() adds a single inode its root's
list of delalloc inodes, so it doesn't make any sense at all for the
function's name to be plural. Rename it to the singular form
btrfs_add_delalloc_inode() to avoid any confusion.
Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/inode.c

@@ -2385,7 +2385,7 @@ void btrfs_merge_delalloc_extent(struct btrfs_inode *inode, struct extent_state
 	spin_unlock(&inode->lock);
 }
 
-static void btrfs_add_delalloc_inodes(struct btrfs_inode *inode)
+static void btrfs_add_delalloc_inode(struct btrfs_inode *inode)
 {
 	struct btrfs_root *root = inode->root;
 	struct btrfs_fs_info *fs_info = root->fs_info;
@@ -2472,7 +2472,7 @@ void btrfs_set_delalloc_extent(struct btrfs_inode *inode, struct extent_state *s
 			inode->defrag_bytes += len;
 		if (do_list && !test_bit(BTRFS_INODE_IN_DELALLOC_LIST,
 					 &inode->runtime_flags))
-			btrfs_add_delalloc_inodes(inode);
+			btrfs_add_delalloc_inode(inode);
 		spin_unlock(&inode->lock);
 	}