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 across 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 separately 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/slab.h>
  49 #include <linux/swap.h>
  50 #include "nilfs.h"
  51 #include "page.h"
  52 #include "mdt.h"
  53 #include "dat.h"
  54 #include "ifile.h"
  55
  56 static const struct address_space_operations def_gcinode_aops = {
  57         .sync_page              = block_sync_page,
  58 };
  59
  60 /*
  61  * nilfs_gccache_submit_read_data() - add data buffer and submit read request
  62  * @inode - gc inode
  63  * @blkoff - dummy offset treated as the key for the page cache
  64  * @pbn - physical block number of the block
  65  * @vbn - virtual block number of the block, 0 for non-virtual block
  66  * @out_bh - indirect pointer to a buffer_head struct to receive the results
  67  *
  68  * Description: nilfs_gccache_submit_read_data() registers the data buffer
  69  * specified by @pbn to the GC pagecache with the key @blkoff.
  70  * This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
  71  *
  72  * Return Value: On success, 0 is returned. On Error, one of the following
  73  * negative error code is returned.
  74  *
  75  * %-EIO - I/O error.
  76  *
  77  * %-ENOMEM - Insufficient amount of memory available.
  78  *
  79  * %-ENOENT - The block specified with @pbn does not exist.
  80  */
  81 int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
  82                                    sector_t pbn, __u64 vbn,
  83                                    struct buffer_head **out_bh)
  84 {
  85         struct buffer_head *bh;
  86         int err;
  87
  88         bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
  89         if (unlikely(!bh))
  90                 return -ENOMEM;
  91
  92         if (buffer_uptodate(bh))
  93                 goto out;
  94
  95         if (pbn == 0) {
  96                 struct inode *dat_inode = NILFS_I_NILFS(inode)->ns_dat;
  97                                           /* use original dat, not gc dat. */
  98                 err = nilfs_dat_translate(dat_inode, vbn, &pbn);
  99                 if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
 100                         brelse(bh);
 101                         goto failed;
 102                 }
 103         }
 104
 105         lock_buffer(bh);
 106         if (buffer_uptodate(bh)) {
 107                 unlock_buffer(bh);
 108                 goto out;
 109         }
 110
 111         if (!buffer_mapped(bh)) {
 112                 bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
 113                 set_buffer_mapped(bh);
 114         }
 115         bh->b_blocknr = pbn;
 116         bh->b_end_io = end_buffer_read_sync;
 117         get_bh(bh);
 118         submit_bh(READ, bh);
 119         if (vbn)
 120                 bh->b_blocknr = vbn;
 121  out:
 122         err = 0;
 123         *out_bh = bh;
 124
 125  failed:
 126         unlock_page(bh->b_page);
 127         page_cache_release(bh->b_page);
 128         return err;
 129 }
 130
 131 /*
 132  * nilfs_gccache_submit_read_node() - add node buffer and submit read request
 133  * @inode - gc inode
 134  * @pbn - physical block number for the block
 135  * @vbn - virtual block number for the block
 136  * @out_bh - indirect pointer to a buffer_head struct to receive the results
 137  *
 138  * Description: nilfs_gccache_submit_read_node() registers the node buffer
 139  * specified by @vbn to the GC pagecache.  @pbn can be supplied by the
 140  * caller to avoid translation of the disk block address.
 141  *
 142  * Return Value: On success, 0 is returned. On Error, one of the following
 143  * negative error code is returned.
 144  *
 145  * %-EIO - I/O error.
 146  *
 147  * %-ENOMEM - Insufficient amount of memory available.
 148  */
 149 int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn,
 150                                    __u64 vbn, struct buffer_head **out_bh)
 151 {
 152         int ret = nilfs_btnode_submit_block(&NILFS_I(inode)->i_btnode_cache,
 153                                             vbn ? : pbn, pbn, out_bh);
 154         if (ret == -EEXIST) /* internal code (cache hit) */
 155                 ret = 0;
 156         return ret;
 157 }
 158
 159 int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
 160 {
 161         wait_on_buffer(bh);
 162         if (!buffer_uptodate(bh))
 163                 return -EIO;
 164         if (buffer_dirty(bh))
 165                 return -EEXIST;
 166
 167         if (buffer_nilfs_node(bh))
 168                 nilfs_btnode_mark_dirty(bh);
 169         else
 170                 nilfs_mdt_mark_buffer_dirty(bh);
 171         return 0;
 172 }
 173
 174 /*
 175  * nilfs_init_gccache() - allocate and initialize gc_inode hash table
 176  * @nilfs - the_nilfs
 177  *
 178  * Return Value: On success, 0.
 179  * On error, a negative error code is returned.
 180  */
 181 int nilfs_init_gccache(struct the_nilfs *nilfs)
 182 {
 183         int loop;
 184
 185         BUG_ON(nilfs->ns_gc_inodes_h);
 186
 187         INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
 188
 189         nilfs->ns_gc_inodes_h =
 190                 kmalloc(sizeof(struct hlist_head) * NILFS_GCINODE_HASH_SIZE,
 191                         GFP_NOFS);
 192         if (nilfs->ns_gc_inodes_h == NULL)
 193                 return -ENOMEM;
 194
 195         for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++)
 196                 INIT_HLIST_HEAD(&nilfs->ns_gc_inodes_h[loop]);
 197         return 0;
 198 }
 199
 200 /*
 201  * nilfs_destroy_gccache() - free gc_inode hash table
 202  * @nilfs - the nilfs
 203  */
 204 void nilfs_destroy_gccache(struct the_nilfs *nilfs)
 205 {
 206         if (nilfs->ns_gc_inodes_h) {
 207                 nilfs_remove_all_gcinode(nilfs);
 208                 kfree(nilfs->ns_gc_inodes_h);
 209                 nilfs->ns_gc_inodes_h = NULL;
 210         }
 211 }
 212
 213 static struct inode *alloc_gcinode(struct the_nilfs *nilfs, ino_t ino,
 214                                    __u64 cno)
 215 {
 216         struct inode *inode;
 217         struct nilfs_inode_info *ii;
 218
 219         inode = nilfs_mdt_new_common(nilfs, NULL, ino, GFP_NOFS, 0);
 220         if (!inode)
 221                 return NULL;
 222
 223         inode->i_op = NULL;
 224         inode->i_fop = NULL;
 225         inode->i_mapping->a_ops = &def_gcinode_aops;
 226
 227         ii = NILFS_I(inode);
 228         ii->i_cno = cno;
 229         ii->i_flags = 0;
 230         ii->i_state = 1 << NILFS_I_GCINODE;
 231         ii->i_bh = NULL;
 232         nilfs_bmap_init_gc(ii->i_bmap);
 233
 234         return inode;
 235 }
 236
 237 static unsigned long ihash(ino_t ino, __u64 cno)
 238 {
 239         return hash_long((unsigned long)((ino << 2) + cno),
 240                          NILFS_GCINODE_HASH_BITS);
 241 }
 242
 243 /*
 244  * nilfs_gc_iget() - find or create gc inode with specified (ino,cno)
 245  */
 246 struct inode *nilfs_gc_iget(struct the_nilfs *nilfs, ino_t ino, __u64 cno)
 247 {
 248         struct hlist_head *head = nilfs->ns_gc_inodes_h + ihash(ino, cno);
 249         struct hlist_node *node;
 250         struct inode *inode;
 251
 252         hlist_for_each_entry(inode, node, head, i_hash) {
 253                 if (inode->i_ino == ino && NILFS_I(inode)->i_cno == cno)
 254                         return inode;
 255         }
 256
 257         inode = alloc_gcinode(nilfs, ino, cno);
 258         if (likely(inode)) {
 259                 hlist_add_head(&inode->i_hash, head);
 260                 list_add(&NILFS_I(inode)->i_dirty, &nilfs->ns_gc_inodes);
 261         }
 262         return inode;
 263 }
 264
 265 /*
 266  * nilfs_clear_gcinode() - clear and free a gc inode
 267  */
 268 void nilfs_clear_gcinode(struct inode *inode)
 269 {
 270         nilfs_mdt_destroy(inode);
 271 }
 272
 273 /*
 274  * nilfs_remove_all_gcinode() - remove all inodes from the_nilfs
 275  */
 276 void nilfs_remove_all_gcinode(struct the_nilfs *nilfs)
 277 {
 278         struct hlist_head *head = nilfs->ns_gc_inodes_h;
 279         struct hlist_node *node, *n;
 280         struct inode *inode;
 281         int loop;
 282
 283         for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++, head++) {
 284                 hlist_for_each_entry_safe(inode, node, n, head, i_hash) {
 285                         hlist_del_init(&inode->i_hash);
 286                         list_del_init(&NILFS_I(inode)->i_dirty);
 287                         nilfs_clear_gcinode(inode); /* might sleep */
 288                 }
 289         }
 290 }