buffer: add kernel-doc for bforget() and __bforget()

Distinguish these functions from brelse() and __brelse().

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
Tested-by: Randy Dunlap <[e-mail]>
Cc: Pankaj Raghav <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

fs/buffer.c

···
 }
 EXPORT_SYMBOL(__brelse);
 
-/*
- * bforget() is like brelse(), except it discards any
- * potentially dirty data.
+/**
+ * __bforget - Discard any dirty data in a buffer.
+ * @bh: The buffer to forget.
+ *
+ * This variant of bforget() can be called if @bh is guaranteed to not
+ * be NULL.
  */
 void __bforget(struct buffer_head *bh)
 {

include/linux/buffer_head.h

···
 		__brelse(bh);
 }
 
+/**
+ * bforget - Discard any dirty data in a buffer.
+ * @bh: The buffer to forget.
+ *
+ * Call this function instead of brelse() if the data written to a buffer
+ * no longer needs to be written back.  It will clear the buffer's dirty
+ * flag so writeback of this buffer will be skipped.
+ *
+ * Context: Any context.
+ */
 static inline void bforget(struct buffer_head *bh)
 {
 	if (bh)