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@xxxxxxxxx> and <20080917224953.GB14644@xxxxxxxxx>). This follows the comment. Cc: Joern Engel <joern@xxxxxxxxx> Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx> --- fs/nilfs2/gcinode.c | 21 ++++++++++++++++++++- 1 files changed, 20 insertions(+), 1 deletions(-) diff --git a/fs/nilfs2/gcinode.c b/fs/nilfs2/gcinode.c index 0013952..77615aa 100644 --- a/fs/nilfs2/gcinode.c +++ b/fs/nilfs2/gcinode.c @@ -1,5 +1,5 @@ /* - * 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@xxxxxxxx>. * */ +/* + * 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> -- 1.5.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
