Commit 047180f2 authored by Ryusuke Konishi's avatar Ryusuke Konishi Committed by Linus Torvalds
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nilfs2: insert explanations in gcinode file



The file gcinode.c gives buffer cache functions for on-disk blocks
moved in garbage collection.  Joern Engel has suggested inserting its
explanations in the source file (Message-ID:
<20080917144146.GD8750@logfs.org> and
<20080917224953.GB14644@logfs.org>).

This follows the comment.

Cc: Joern Engel <joern@logfs.org>
Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 47420c79
/*
* gcinode.c - NILFS memory inode for GC
* gcinode.c - dummy inodes to buffer blocks for garbage collection
*
* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
*
......@@ -22,6 +22,25 @@
* Revised by Ryusuke Konishi <ryusuke@osrg.net>.
*
*/
/*
* This file adds the cache of on-disk blocks to be moved in garbage
* collection. The disk blocks are held with dummy inodes (called
* gcinodes), and this file provides lookup function of the dummy
* inodes and their buffer read function.
*
* Since NILFS2 keeps up multiple checkpoints/snapshots accross GC, it
* has to treat blocks that belong to a same file but have different
* checkpoint numbers. To avoid interference among generations, dummy
* inodes are managed separatly from actual inodes, and their lookup
* function (nilfs_gc_iget) is designed to be specified with a
* checkpoint number argument as well as an inode number.
*
* Buffers and pages held by the dummy inodes will be released each
* time after they are copied to a new log. Dirty blocks made on the
* current generation and the blocks to be moved by GC never overlap
* because the dirty blocks make a new generation; they rather must be
* written individually.
*/
#include <linux/buffer_head.h>
#include <linux/mpage.h>
......
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