Merge commit 'origin/master' into next

[pandora-kernel.git] / fs / nilfs2 / gcinode.c

diff --git a/fs/nilfs2/gcinode.c b/fs/nilfs2/gcinode.c
index 0013952..1b3c2bb 100644 (file)
--- 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@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>
@@ -33,8 +52,9 @@
 #include "dat.h"
 #include "ifile.h"
 
-static struct address_space_operations def_gcinode_aops = {};
-/* XXX need def_gcinode_iops/fops? */
+static struct address_space_operations def_gcinode_aops = {
+       .sync_page              = block_sync_page,
+};
 
 /*
  * nilfs_gccache_submit_read_data() - add data buffer and submit read request
@@ -207,7 +227,6 @@ static struct inode *alloc_gcinode(struct the_nilfs *nilfs, ino_t ino,
        ii->i_flags = 0;
        ii->i_state = 1 << NILFS_I_GCINODE;
        ii->i_bh = NULL;
-       ii->i_dtime = 0;
        nilfs_bmap_init_gc(ii->i_bmap);
 
        return inode;