Linux Kernel  3.7.1
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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 <[email protected]>, Amagai Yoshiji <[email protected]>,
21  * and Ryusuke Konishi <[email protected]>.
22  * Revised by Ryusuke Konishi <[email protected]>.
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  */
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  */
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 
152 int 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 
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;
179 
180  return 0;
181 }
182 
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);
196  iput(&ii->vfs_inode);
197  }
198 }