add formats for dentry/file pathnames

New formats: %p[dD][234]?.  The next pointer is interpreted as struct dentry *
or struct file * resp. ('d' => dentry, 'D' => file) and the last component(s)
of pathname are printed (%pd => just the last one, %pd2 => the last two, etc.)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 9 insertions, 0 deletions

diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 3e8cb73ac43c..9552a3299ec9 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -168,6 +168,15 @@ UUID/GUID addresses:
 	Where no additional specifiers are used the default little endian
 	order with lower case hex characters will be printed.
 
+dentry names:
+	%pd{,2,3,4}
+	%pD{,2,3,4}
+
+	For printing dentry name; if we race with d_move(), the name might be
+	a mix of old and new ones, but it won't oops.  %pd dentry is a safer
+	equivalent of %s dentry->d_name.name we used to use, %pd<n> prints
+	n last components.  %pD does the same thing for struct file.
+
 struct va_format:
 
 	%pV