Include description of 'debugfs_create_dir_with_tmpfiles()' call.
Signed-off-by: Roman Pen <r.peni...@gmail.com>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org
---
Documentation/filesystems/debugfs.txt | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/Documentation/filesystems/debugfs.txt
b/Documentation/filesystems/debugfs.txt
index 4f45f71..150fabf 100644
--- a/Documentation/filesystems/debugfs.txt
+++ b/Documentation/filesystems/debugfs.txt
@@ -36,6 +36,31 @@ wrong. If ERR_PTR(-ENODEV) is returned, that is an
indication that the
kernel has been built without debugfs support and none of the functions
described below will work.
+Another way to create a directory where temporary files will be created
+on demand is:
+
+ struct dentry *debugfs_create_dir_with_tmpfiles(const char *name,
+ umode_t mode, struct dentry *parent, void *data,
+ const struct file_operations *fops);
+
+This function creates a directory in debugfs with the given name with
+possibility to create temporary files on demand. Any attempt to open
+a non-existent file in that directory will create a temporary file,
+wich will be deleted when the last file descriptor is closed. This
+temporary file is very similar to opening a directory with O_TMPFILE,
+with the difference that a resulting dentry has a name, but still is
+unhashed, so is invisible to outer world and can never be reached via
+any pathname.
+
+How those temporary files on demand can be used? This is a way to provide
+one additional parameter in a file name and specify an object name. E.g.:
+
+ # cat /sys/kernel/debug/my_objects/$UUID
+
+Where $UUID is a UUID of an object which should be requested. This $UUID
+file will never appear in lookup and will be deleted when 'cat' closes last
+file descriptor.
+
The most general way to create a file within a debugfs directory is with:
struct dentry *debugfs_create_file(const char *name, umode_t mode,
--
2.6.2
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