1 files changed, 15 insertions, 4 deletions

diff --git a/Documentation/filesystems/seq_file.txt b/Documentation/filesystems/seq_file.txt
index 7fb8e6dc62bf..b843743aa0b5 100644
--- a/Documentation/filesystems/seq_file.txt
+++ b/Documentation/filesystems/seq_file.txt
@@ -122,8 +122,7 @@ stop() is the place to free it.
         }
 
 Finally, the show() function should format the object currently pointed to
-by the iterator for output. It should return zero, or an error code if
-something goes wrong. The example module's show() function is:
+by the iterator for output.  The example module's show() function is:
 
         static int ct_seq_show(struct seq_file *s, void *v)
         {
@@ -132,6 +131,12 @@ something goes wrong. The example module's show() function is:
                 return 0;
         }
 
+If all is well, the show() function should return zero.  A negative error
+code in the usual manner indicates that something went wrong; it will be
+passed back to user space.  This function can also return SEQ_SKIP, which
+causes the current item to be skipped; if the show() function has already
+generated output before returning SEQ_SKIP, that output will be dropped.
+
 We will look at seq_printf() in a moment. But first, the definition of the
 seq_file iterator is finished by creating a seq_operations structure with
 the four functions we have just defined:
@@ -182,12 +187,18 @@ The first two output a single character and a string, just like one would
 expect. seq_escape() is like seq_puts(), except that any character in s
 which is in the string esc will be represented in octal form in the output.
 
-There is also a function for printing filenames:
+There is also a pair of functions for printing filenames:
 
         int seq_path(struct seq_file *m, struct path *path, char *esc);
+        int seq_path_root(struct seq_file *m, struct path *path,
+                          struct path *root, char *esc)
 
 Here, path indicates the file of interest, and esc is a set of characters
-which should be escaped in the output.
+which should be escaped in the output.  A call to seq_path() will output
+the path relative to the current process's filesystem root.  If a different
+root is desired, it can be used with seq_path_root().  Note that, if it
+turns out that path cannot be reached from root, the value of root will be
+changed in seq_file_root() to a root which *does* work.
 
 
 Making it all work