original development tree for Linux kernel GTP module; now long in mainline.
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/*
* gcinode.c - dummy inodes to buffer blocks for garbage collection
*
* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* Written by Seiji Kihara <kihara@osrg.net>, Amagai Yoshiji <amagai@osrg.net>,
* and Ryusuke Konishi <ryusuke@osrg.net>.
* 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.
*
* 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>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include "nilfs.h"
#include "btree.h"
#include "btnode.h"
#include "page.h"
#include "mdt.h"
#include "dat.h"
#include "ifile.h"
/*
* nilfs_gccache_submit_read_data() - add data buffer and submit read request
* @inode - gc inode
* @blkoff - dummy offset treated as the key for the page cache
* @pbn - physical block number of the block
* @vbn - virtual block number of the block, 0 for non-virtual block
* @out_bh - indirect pointer to a buffer_head struct to receive the results
*
* Description: nilfs_gccache_submit_read_data() registers the data buffer
* specified by @pbn to the GC pagecache with the key @blkoff.
* This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
*
* Return Value: On success, 0 is returned. On Error, one of the following
* negative error code is returned.
*
* %-EIO - I/O error.
*
* %-ENOMEM - Insufficient amount of memory available.
*
* %-ENOENT - The block specified with @pbn does not exist.
*/
int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
sector_t pbn, __u64 vbn,
struct buffer_head **out_bh)
{
struct buffer_head *bh;
int err;
bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
if (unlikely(!bh))
return -ENOMEM;
if (buffer_uptodate(bh))
goto out;
if (pbn == 0) {
struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
err = nilfs_dat_translate(nilfs->ns_dat, vbn, &pbn);
if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
brelse(bh);
goto failed;
}
}
lock_buffer(bh);
if (buffer_uptodate(bh)) {
unlock_buffer(bh);
goto out;
}
if (!buffer_mapped(bh)) {
bh->b_bdev = inode->i_sb->s_bdev;
set_buffer_mapped(bh);
}
bh->b_blocknr = pbn;
bh->b_end_io = end_buffer_read_sync;
get_bh(bh);
submit_bh(READ, bh);
if (vbn)
bh->b_blocknr = vbn;
out:
err = 0;
*out_bh = bh;
failed:
unlock_page(bh->b_page);
page_cache_release(bh->b_page);
return err;
}
/*
* nilfs_gccache_submit_read_node() - add node buffer and submit read request
* @inode - gc inode
* @pbn - physical block number for the block
* @vbn - virtual block number for the block
* @out_bh - indirect pointer to a buffer_head struct to receive the results
*
* Description: nilfs_gccache_submit_read_node() registers the node buffer
* specified by @vbn to the GC pagecache. @pbn can be supplied by the
* caller to avoid translation of the disk block address.
*
* Return Value: On success, 0 is returned. On Error, one of the following
* negative error code is returned.
*
* %-EIO - I/O error.
*
* %-ENOMEM - Insufficient amount of memory available.
*/
int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn,
__u64 vbn, struct buffer_head **out_bh)
{
int ret;
ret = nilfs_btnode_submit_block(&NILFS_I(inode)->i_btnode_cache,
vbn ? : pbn, pbn, READ, out_bh, &pbn);
if (ret == -EEXIST) /* internal code (cache hit) */
ret = 0;
return ret;
}
int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
{
wait_on_buffer(bh);
if (!buffer_uptodate(bh))
return -EIO;
if (buffer_dirty(bh))
return -EEXIST;
if (buffer_nilfs_node(bh) && nilfs_btree_broken_node_block(bh)) {
clear_buffer_uptodate(bh);
return -EIO;
}
mark_buffer_dirty(bh);
return 0;
}
int nilfs_init_gcinode(struct inode *inode)
{
struct nilfs_inode_info *ii = NILFS_I(inode);
inode->i_mode = S_IFREG;
mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
inode->i_mapping->a_ops = &empty_aops;
inode->i_mapping->backing_dev_info = inode->i_sb->s_bdi;
ii->i_flags = 0;
nilfs_bmap_init_gc(ii->i_bmap);
return 0;
}
/**
* nilfs_remove_all_gcinodes() - remove all unprocessed gc inodes
*/
void nilfs_remove_all_gcinodes(struct the_nilfs *nilfs)
{
struct list_head *head = &nilfs->ns_gc_inodes;
struct nilfs_inode_info *ii;
while (!list_empty(head)) {
ii = list_first_entry(head, struct nilfs_inode_info, i_dirty);
list_del_init(&ii->i_dirty);
truncate_inode_pages(&ii->vfs_inode.i_data, 0);
nilfs_btnode_cache_clear(&ii->i_btnode_cache);
iput(&ii->vfs_inode);
}
}