The patch titled
nilfs2: insert explanations in gcinode file
has been added to the -mm tree. Its filename is
nilfs2-insert-explanations-in-gcinode-file.patch
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------------------------------------------------------
Subject: nilfs2: insert explanations in gcinode file
From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
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>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/nilfs2/gcinode.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff -puN fs/nilfs2/gcinode.c~nilfs2-insert-explanations-in-gcinode-file fs/nilfs2/gcinode.c
--- a/fs/nilfs2/gcinode.c~nilfs2-insert-explanations-in-gcinode-file
+++ a/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>
_
Patches currently in -mm which might be from konishi.ryusuke@xxxxxxxxxxxxx are
nilfs2-add-document.patch
nilfs2-disk-format-and-userland-interface.patch
nilfs2-add-inode-and-other-major-structures.patch
nilfs2-integrated-block-mapping.patch
nilfs2-b-tree-based-block-mapping.patch
nilfs2-direct-block-mapping.patch
nilfs2-b-tree-node-cache.patch
nilfs2-buffer-and-page-operations.patch
nilfs2-meta-data-file.patch
nilfs2-persistent-object-allocator.patch
nilfs2-disk-address-translator.patch
nilfs2-inode-map-file.patch
nilfs2-checkpoint-file.patch
nilfs2-segment-usage-file.patch
nilfs2-inode-operations.patch
nilfs2-inode-operations-fix.patch
nilfs2-file-operations.patch
nilfs2-directory-entry-operations.patch
nilfs2-pathname-operations.patch
nilfs2-pathname-operations-fix.patch
nilfs2-operations-for-the_nilfs-core-object.patch
nilfs2-super-block-operations.patch
nilfs2-super-block-operations-fix.patch
nilfs2-segment-buffer.patch
nilfs2-segment-constructor.patch
nilfs2-recovery-functions.patch
nilfs2-another-dat-for-garbage-collection.patch
nilfs2-block-cache-for-garbage-collection.patch
nilfs2-ioctl-operations.patch
nilfs2-update-makefile-and-kconfig.patch
nilfs2-fix-problems-of-memory-allocation-in-ioctl.patch
nilfs2-cleanup-nilfs_clear_inode.patch
nilfs2-avoid-double-error-caused-by-nilfs_transaction_end.patch
nilfs2-insert-explanations-in-gcinode-file.patch
nilfs2-add-maintainer.patch
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