linux/fs/nilfs2/gcinode.c
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   1/*
   2 * gcinode.c - dummy inodes to buffer blocks for garbage collection
   3 *
   4 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program; if not, write to the Free Software
  18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19 *
  20 * Written by Seiji Kihara <kihara@osrg.net>, Amagai Yoshiji <amagai@osrg.net>,
  21 *            and Ryusuke Konishi <ryusuke@osrg.net>.
  22 * Revised by Ryusuke Konishi <ryusuke@osrg.net>.
  23 *
  24 */
  25/*
  26 * This file adds the cache of on-disk blocks to be moved in garbage
  27 * collection.  The disk blocks are held with dummy inodes (called
  28 * gcinodes), and this file provides lookup function of the dummy
  29 * inodes and their buffer read function.
  30 *
  31 * Buffers and pages held by the dummy inodes will be released each
  32 * time after they are copied to a new log.  Dirty blocks made on the
  33 * current generation and the blocks to be moved by GC never overlap
  34 * because the dirty blocks make a new generation; they rather must be
  35 * written individually.
  36 */
  37
  38#include <linux/buffer_head.h>
  39#include <linux/mpage.h>
  40#include <linux/hash.h>
  41#include <linux/slab.h>
  42#include <linux/swap.h>
  43#include "nilfs.h"
  44#include "btree.h"
  45#include "btnode.h"
  46#include "page.h"
  47#include "mdt.h"
  48#include "dat.h"
  49#include "ifile.h"
  50
  51/*
  52 * nilfs_gccache_submit_read_data() - add data buffer and submit read request
  53 * @inode - gc inode
  54 * @blkoff - dummy offset treated as the key for the page cache
  55 * @pbn - physical block number of the block
  56 * @vbn - virtual block number of the block, 0 for non-virtual block
  57 * @out_bh - indirect pointer to a buffer_head struct to receive the results
  58 *
  59 * Description: nilfs_gccache_submit_read_data() registers the data buffer
  60 * specified by @pbn to the GC pagecache with the key @blkoff.
  61 * This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
  62 *
  63 * Return Value: On success, 0 is returned. On Error, one of the following
  64 * negative error code is returned.
  65 *
  66 * %-EIO - I/O error.
  67 *
  68 * %-ENOMEM - Insufficient amount of memory available.
  69 *
  70 * %-ENOENT - The block specified with @pbn does not exist.
  71 */
  72int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
  73                                   sector_t pbn, __u64 vbn,
  74                                   struct buffer_head **out_bh)
  75{
  76        struct buffer_head *bh;
  77        int err;
  78
  79        bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
  80        if (unlikely(!bh))
  81                return -ENOMEM;
  82
  83        if (buffer_uptodate(bh))
  84                goto out;
  85
  86        if (pbn == 0) {
  87                struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
  88
  89                err = nilfs_dat_translate(nilfs->ns_dat, vbn, &pbn);
  90                if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
  91                        brelse(bh);
  92                        goto failed;
  93                }
  94        }
  95
  96        lock_buffer(bh);
  97        if (buffer_uptodate(bh)) {
  98                unlock_buffer(bh);
  99                goto out;
 100        }
 101
 102        if (!buffer_mapped(bh)) {
 103                bh->b_bdev = inode->i_sb->s_bdev;
 104                set_buffer_mapped(bh);
 105        }
 106        bh->b_blocknr = pbn;
 107        bh->b_end_io = end_buffer_read_sync;
 108        get_bh(bh);
 109        submit_bh(READ, bh);
 110        if (vbn)
 111                bh->b_blocknr = vbn;
 112 out:
 113        err = 0;
 114        *out_bh = bh;
 115
 116 failed:
 117        unlock_page(bh->b_page);
 118        page_cache_release(bh->b_page);
 119        return err;
 120}
 121
 122/*
 123 * nilfs_gccache_submit_read_node() - add node buffer and submit read request
 124 * @inode - gc inode
 125 * @pbn - physical block number for the block
 126 * @vbn - virtual block number for the block
 127 * @out_bh - indirect pointer to a buffer_head struct to receive the results
 128 *
 129 * Description: nilfs_gccache_submit_read_node() registers the node buffer
 130 * specified by @vbn to the GC pagecache.  @pbn can be supplied by the
 131 * caller to avoid translation of the disk block address.
 132 *
 133 * Return Value: On success, 0 is returned. On Error, one of the following
 134 * negative error code is returned.
 135 *
 136 * %-EIO - I/O error.
 137 *
 138 * %-ENOMEM - Insufficient amount of memory available.
 139 */
 140int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn,
 141                                   __u64 vbn, struct buffer_head **out_bh)
 142{
 143        int ret;
 144
 145        ret = nilfs_btnode_submit_block(&NILFS_I(inode)->i_btnode_cache,
 146                                        vbn ? : pbn, pbn, READ, out_bh, &pbn);
 147        if (ret == -EEXIST) /* internal code (cache hit) */
 148                ret = 0;
 149        return ret;
 150}
 151
 152int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
 153{
 154        wait_on_buffer(bh);
 155        if (!buffer_uptodate(bh))
 156                return -EIO;
 157        if (buffer_dirty(bh))
 158                return -EEXIST;
 159
 160        if (buffer_nilfs_node(bh) && nilfs_btree_broken_node_block(bh)) {
 161                clear_buffer_uptodate(bh);
 162                return -EIO;
 163        }
 164        mark_buffer_dirty(bh);
 165        return 0;
 166}
 167
 168int nilfs_init_gcinode(struct inode *inode)
 169{
 170        struct nilfs_inode_info *ii = NILFS_I(inode);
 171
 172        inode->i_mode = S_IFREG;
 173        mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
 174        inode->i_mapping->a_ops = &empty_aops;
 175        inode->i_mapping->backing_dev_info = inode->i_sb->s_bdi;
 176
 177        ii->i_flags = 0;
 178        nilfs_bmap_init_gc(ii->i_bmap);
 179
 180        return 0;
 181}
 182
 183/**
 184 * nilfs_remove_all_gcinodes() - remove all unprocessed gc inodes
 185 */
 186void nilfs_remove_all_gcinodes(struct the_nilfs *nilfs)
 187{
 188        struct list_head *head = &nilfs->ns_gc_inodes;
 189        struct nilfs_inode_info *ii;
 190
 191        while (!list_empty(head)) {
 192                ii = list_first_entry(head, struct nilfs_inode_info, i_dirty);
 193                list_del_init(&ii->i_dirty);
 194                truncate_inode_pages(&ii->vfs_inode.i_data, 0);
 195                nilfs_btnode_cache_clear(&ii->i_btnode_cache);
 196                iput(&ii->vfs_inode);
 197        }
 198}
 199
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