diff --git a/fs/namei.c b/fs/namei.c
index ffcd4e114b6e34c1f13a727bd01bacb286547036..5abab917690345dba94a2eadb76524ba14965ce2 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2192,6 +2192,19 @@ static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode)
 	return security_inode_create(dir->dentry->d_inode, dentry, mode);
 }
 
+/*
+ * Attempt to atomically look up, create and open a file from a negative
+ * dentry.
+ *
+ * Returns 0 if successful.  The file will have been created and attached to
+ * @file by the filesystem calling finish_open().
+ *
+ * Returns 1 if the file was looked up only or didn't need creating.  The
+ * caller will need to perform the open themselves.  @path will have been
+ * updated to point to the new dentry.  This may be negative.
+ *
+ * Returns an error code otherwise.
+ */
 static int atomic_open(struct nameidata *nd, struct dentry *dentry,
 			struct path *path, struct file *file,
 			const struct open_flags *op,
@@ -2336,12 +2349,22 @@ static int atomic_open(struct nameidata *nd, struct dentry *dentry,
 }
 
 /*
- * Lookup, maybe create and open the last component
+ * Look up and maybe create and open the last component.
  *
  * Must be called with i_mutex held on parent.
  *
- * Returns open file or NULL on success, error otherwise.  NULL means no open
- * was performed, only lookup.
+ * Returns 0 if the file was successfully atomically created (if necessary) and
+ * opened.  In this case the file will be returned attached to @file.
+ *
+ * Returns 1 if the file was not completely opened at this time, though lookups
+ * and creations will have been performed and the dentry returned in @path will
+ * be positive upon return if O_CREAT was specified.  If O_CREAT wasn't
+ * specified then a negative dentry may be returned.
+ *
+ * An error code is returned otherwise.
+ *
+ * FILE_CREATE will be set in @*opened if the dentry was created and will be
+ * cleared otherwise prior to returning.
  */
 static int lookup_open(struct nameidata *nd, struct path *path,
 			struct file *file,