fs/nilfs2/gcinode.c

   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  * Since NILFS2 keeps up multiple checkpoints/snapshots accross GC, it
  32  * has to treat blocks that belong to a same file but have different
  33  * checkpoint numbers.  To avoid interference among generations, dummy
  34  * inodes are managed separatly from actual inodes, and their lookup
  35  * function (nilfs_gc_iget) is designed to be specified with a
  36  * checkpoint number argument as well as an inode number.
  37  *
  38  * Buffers and pages held by the dummy inodes will be released each
  39  * time after they are copied to a new log.  Dirty blocks made on the
  40  * current generation and the blocks to be moved by GC never overlap
  41  * because the dirty blocks make a new generation; they rather must be
  42  * written individually.
  43  */
  44
  45 #include <linux/buffer_head.h>
  46 #include <linux/mpage.h>
  47 #include <linux/hash.h>
  48 #include <linux/swap.h>
  49 #include "nilfs.h"
  50 #include "page.h"
  51 #include "mdt.h"
  52 #include "dat.h"
  53 #include "ifile.h"
  54
  55 static struct address_space_operations def_gcinode_aops = {};
  56 /* XXX need def_gcinode_iops/fops? */
  57
  58 /*
  59  * nilfs_gccache_submit_read_data() - add data buffer and submit read request
  60  * @inode - gc inode
  61  * @blkoff - dummy offset treated as the key for the page cache
  62  * @pbn - physical block number of the block
  63  * @vbn - virtual block number of the block, 0 for non-virtual block
  64  * @out_bh - indirect pointer to a buffer_head struct to receive the results
  65  *
  66  * Description: nilfs_gccache_submit_read_data() registers the data buffer
  67  * specified by @pbn to the GC pagecache with the key @blkoff.
  68  * This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
  69  *
  70  * Return Value: On success, 0 is returned. On Error, one of the following
  71  * negative error code is returned.
  72  *
  73  * %-EIO - I/O error.
  74  *
  75  * %-ENOMEM - Insufficient amount of memory available.
  76  *
  77  * %-ENOENT - The block specified with @pbn does not exist.
  78  */
  79 int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
  80                                    sector_t pbn, __u64 vbn,
  81                                    struct buffer_head **out_bh)
  82 {
  83         struct buffer_head *bh;
  84         int err;
  85
  86         bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
  87         if (unlikely(!bh))
  88                 return -ENOMEM;
  89
  90         if (buffer_uptodate(bh))
  91                 goto out;
  92
  93         if (pbn == 0) {
  94                 struct inode *dat_inode = NILFS_I_NILFS(inode)->ns_dat;
  95                                           /* use original dat, not gc dat. */
  96                 err = nilfs_dat_translate(dat_inode, vbn, &pbn);
  97                 if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
  98                         brelse(bh);
  99                         goto failed;
 100                 }
 101         }
 102
 103         lock_buffer(bh);
 104         if (buffer_uptodate(bh)) {
 105                 unlock_buffer(bh);
 106                 goto out;
 107         }
 108
 109         if (!buffer_mapped(bh)) {
 110                 bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
 111                 set_buffer_mapped(bh);
 112         }
 113         bh->b_blocknr = pbn;
 114         bh->b_end_io = end_buffer_read_sync;
 115         get_bh(bh);
 116         submit_bh(READ, bh);
 117         if (vbn)
 118                 bh->b_blocknr = vbn;
 119  out:
 120         err = 0;
 121         *out_bh = bh;
 122
 123  failed:
 124         unlock_page(bh->b_page);
 125         page_cache_release(bh->b_page);
 126         return err;
 127 }
 128
 129 /*
 130  * nilfs_gccache_submit_read_node() - add node buffer and submit read request
 131  * @inode - gc inode
 132  * @pbn - physical block number for the block
 133  * @vbn - virtual block number for the block
 134  * @out_bh - indirect pointer to a buffer_head struct to receive the results
 135  *
 136  * Description: nilfs_gccache_submit_read_node() registers the node buffer
 137  * specified by @vbn to the GC pagecache.  @pbn can be supplied by the
 138  * caller to avoid translation of the disk block address.
 139  *
 140  * Return Value: On success, 0 is returned. On Error, one of the following
 141  * negative error code is returned.
 142  *
 143  * %-EIO - I/O error.
 144  *
 145  * %-ENOMEM - Insufficient amount of memory available.
 146  */
 147 int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn,
 148                                    __u64 vbn, struct buffer_head **out_bh)
 149 {
 150         int ret = nilfs_btnode_submit_block(&NILFS_I(inode)->i_btnode_cache,
 151                                             vbn ? : pbn, pbn, out_bh, 0);
 152         if (ret == -EEXIST) /* internal code (cache hit) */
 153                 ret = 0;
 154         return ret;
 155 }
 156
 157 int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
 158 {
 159         wait_on_buffer(bh);
 160         if (!buffer_uptodate(bh))
 161                 return -EIO;
 162         if (buffer_dirty(bh))
 163                 return -EEXIST;
 164
 165         if (buffer_nilfs_node(bh))
 166                 nilfs_btnode_mark_dirty(bh);
 167         else
 168                 nilfs_mdt_mark_buffer_dirty(bh);
 169         return 0;
 170 }
 171
 172 /*
 173  * nilfs_init_gccache() - allocate and initialize gc_inode hash table
 174  * @nilfs - the_nilfs
 175  *
 176  * Return Value: On success, 0.
 177  * On error, a negative error code is returned.
 178  */
 179 int nilfs_init_gccache(struct the_nilfs *nilfs)
 180 {
 181         int loop;
 182
 183         BUG_ON(nilfs->ns_gc_inodes_h);
 184
 185         INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
 186
 187         nilfs->ns_gc_inodes_h =
 188                 kmalloc(sizeof(struct hlist_head) * NILFS_GCINODE_HASH_SIZE,
 189                         GFP_NOFS);
 190         if (nilfs->ns_gc_inodes_h == NULL)
 191                 return -ENOMEM;
 192
 193         for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++)
 194                 INIT_HLIST_HEAD(&nilfs->ns_gc_inodes_h[loop]);
 195         return 0;
 196 }
 197
 198 /*
 199  * nilfs_destroy_gccache() - free gc_inode hash table
 200  * @nilfs - the nilfs
 201  */
 202 void nilfs_destroy_gccache(struct the_nilfs *nilfs)
 203 {
 204         if (nilfs->ns_gc_inodes_h) {
 205                 nilfs_remove_all_gcinode(nilfs);
 206                 kfree(nilfs->ns_gc_inodes_h);
 207                 nilfs->ns_gc_inodes_h = NULL;
 208         }
 209 }
 210
 211 static struct inode *alloc_gcinode(struct the_nilfs *nilfs, ino_t ino,
 212                                    __u64 cno)
 213 {
 214         struct inode *inode = nilfs_mdt_new_common(nilfs, NULL, ino, GFP_NOFS);
 215         struct nilfs_inode_info *ii;
 216
 217         if (!inode)
 218                 return NULL;
 219
 220         inode->i_op = NULL;
 221         inode->i_fop = NULL;
 222         inode->i_mapping->a_ops = &def_gcinode_aops;
 223
 224         ii = NILFS_I(inode);
 225         ii->i_cno = cno;
 226         ii->i_flags = 0;
 227         ii->i_state = 1 << NILFS_I_GCINODE;
 228         ii->i_bh = NULL;
 229         nilfs_bmap_init_gc(ii->i_bmap);
 230
 231         return inode;
 232 }
 233
 234 static unsigned long ihash(ino_t ino, __u64 cno)
 235 {
 236         return hash_long((unsigned long)((ino << 2) + cno),
 237                          NILFS_GCINODE_HASH_BITS);
 238 }
 239
 240 /*
 241  * nilfs_gc_iget() - find or create gc inode with specified (ino,cno)
 242  */
 243 struct inode *nilfs_gc_iget(struct the_nilfs *nilfs, ino_t ino, __u64 cno)
 244 {
 245         struct hlist_head *head = nilfs->ns_gc_inodes_h + ihash(ino, cno);
 246         struct hlist_node *node;
 247         struct inode *inode;
 248
 249         hlist_for_each_entry(inode, node, head, i_hash) {
 250                 if (inode->i_ino == ino && NILFS_I(inode)->i_cno == cno)
 251                         return inode;
 252         }
 253
 254         inode = alloc_gcinode(nilfs, ino, cno);
 255         if (likely(inode)) {
 256                 hlist_add_head(&inode->i_hash, head);
 257                 list_add(&NILFS_I(inode)->i_dirty, &nilfs->ns_gc_inodes);
 258         }
 259         return inode;
 260 }
 261
 262 /*
 263  * nilfs_clear_gcinode() - clear and free a gc inode
 264  */
 265 void nilfs_clear_gcinode(struct inode *inode)
 266 {
 267         nilfs_mdt_clear(inode);
 268         nilfs_mdt_destroy(inode);
 269 }
 270
 271 /*
 272  * nilfs_remove_all_gcinode() - remove all inodes from the_nilfs
 273  */
 274 void nilfs_remove_all_gcinode(struct the_nilfs *nilfs)
 275 {
 276         struct hlist_head *head = nilfs->ns_gc_inodes_h;
 277         struct hlist_node *node, *n;
 278         struct inode *inode;
 279         int loop;
 280
 281         for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++, head++) {
 282                 hlist_for_each_entry_safe(inode, node, n, head, i_hash) {
 283                         hlist_del_init(&inode->i_hash);
 284                         list_del_init(&NILFS_I(inode)->i_dirty);
 285                         nilfs_clear_gcinode(inode); /* might sleep */
 286                 }
 287         }
 288 }