Unified diff: What does @@ mean?

Question

--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1147,8 +1147,8 @@ static struct dentry *__lookup_hash(struct qstr *name, struct dentry *base,
  *  small and for now I'd prefer to have fast path as straight as possible.
  *  It _is_ time-critical.
  */
-static int do_lookup(struct nameidata *nd, struct qstr *name,
-           struct path *path, struct inode **inode)
+static int lookup_fast(struct nameidata *nd, struct qstr *name,
+              struct path *path, struct inode **inode)
 {
    struct vfsmount *mnt = nd->path.mnt;
    struct dentry *dentry, *parent = nd->path.dentry;
@@ -1217,7 +1217,6 @@ unlazy:
        }
    }

This is a code piece. What does this line mean？ Could anyone explain it to me? Thank you!

Answer 1

It's simply a block marker. If you want to find out more about the format, searching for "unified diff" might help.

Everything in the line after the second @@ is ignored so it's often used to display the function header related to the code block.