release/src-rt-6.x.4708/linux/linux-2.6.36/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 "btree.h"
  52 #include "btnode.h"
  53 #include "page.h"
  54 #include "mdt.h"
  55 #include "dat.h"
  56 #include "ifile.h"
  57
  58 static const struct address_space_operations def_gcinode_aops = {
  59         .sync_page              = block_sync_page,
  60 };
  61
  62 /*
  63  * nilfs_gccache_submit_read_data() - add data buffer and submit read request
  64  * @inode - gc inode
  65  * @blkoff - dummy offset treated as the key for the page cache
  66  * @pbn - physical block number of the block
  67  * @vbn - virtual block number of the block, 0 for non-virtual block
  68  * @out_bh - indirect pointer to a buffer_head struct to receive the results
  69  *
  70  * Description: nilfs_gccache_submit_read_data() registers the data buffer
  71  * specified by @pbn to the GC pagecache with the key @blkoff.
  72  * This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
  73  *
  74  * Return Value: On success, 0 is returned. On Error, one of the following
  75  * negative error code is returned.
  76  *
  77  * %-EIO - I/O error.
  78  *
  79  * %-ENOMEM - Insufficient amount of memory available.
  80  *
  81  * %-ENOENT - The block specified with @pbn does not exist.
  82  */
  83 int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
  84                                    sector_t pbn, __u64 vbn,
  85                                    struct buffer_head **out_bh)
  86 {
  87         struct buffer_head *bh;
  88         int err;
  89
  90         bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
  91         if (unlikely(!bh))
  92                 return -ENOMEM;
  93
  94         if (buffer_uptodate(bh))
  95                 goto out;
  96
  97         if (pbn == 0) {
  98                 struct inode *dat_inode = NILFS_I_NILFS(inode)->ns_dat;
  99                                           /* use original dat, not gc dat. */
 100                 err = nilfs_dat_translate(dat_inode, vbn, &pbn);
 101                 if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
 102                         brelse(bh);
 103                         goto failed;
 104                 }
 105         }
 106
 107         lock_buffer(bh);
 108         if (buffer_uptodate(bh)) {
 109                 unlock_buffer(bh);
 110                 goto out;
 111         }
 112
 113         if (!buffer_mapped(bh)) {
 114                 bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
 115                 set_buffer_mapped(bh);
 116         }
 117         bh->b_blocknr = pbn;
 118         bh->b_end_io = end_buffer_read_sync;
 119         get_bh(bh);
 120         submit_bh(READ, bh);
 121         if (vbn)
 122                 bh->b_blocknr = vbn;
 123  out:
 124         err = 0;
 125         *out_bh = bh;
 126
 127  failed:
 128         unlock_page(bh->b_page);
 129         page_cache_release(bh->b_page);
 130         return err;
 131 }
 132
 133 /*
 134  * nilfs_gccache_submit_read_node() - add node buffer and submit read request
 135  * @inode - gc inode
 136  * @pbn - physical block number for the block
 137  * @vbn - virtual block number for the block
 138  * @out_bh - indirect pointer to a buffer_head struct to receive the results
 139  *
 140  * Description: nilfs_gccache_submit_read_node() registers the node buffer
 141  * specified by @vbn to the GC pagecache.  @pbn can be supplied by the
 142  * caller to avoid translation of the disk block address.
 143  *
 144  * Return Value: On success, 0 is returned. On Error, one of the following
 145  * negative error code is returned.
 146  *
 147  * %-EIO - I/O error.
 148  *
 149  * %-ENOMEM - Insufficient amount of memory available.
 150  */
 151 int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn,
 152                                    __u64 vbn, struct buffer_head **out_bh)
 153 {
 154         int ret;
 155
 156         ret = nilfs_btnode_submit_block(&NILFS_I(inode)->i_btnode_cache,
 157                                         vbn ? : pbn, pbn, READ, out_bh, &pbn);
 158         if (ret == -EEXIST) /* internal code (cache hit) */
 159                 ret = 0;
 160         return ret;
 161 }
 162
 163 int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
 164 {
 165         wait_on_buffer(bh);
 166         if (!buffer_uptodate(bh))
 167                 return -EIO;
 168         if (buffer_dirty(bh))
 169                 return -EEXIST;
 170
 171         if (buffer_nilfs_node(bh)) {
 172                 if (nilfs_btree_broken_node_block(bh)) {
 173                         clear_buffer_uptodate(bh);
 174                         return -EIO;
 175                 }
 176                 nilfs_btnode_mark_dirty(bh);
 177         } else {
 178                 nilfs_mdt_mark_buffer_dirty(bh);
 179         }
 180         return 0;
 181 }
 182
 183 /*
 184  * nilfs_init_gccache() - allocate and initialize gc_inode hash table
 185  * @nilfs - the_nilfs
 186  *
 187  * Return Value: On success, 0.
 188  * On error, a negative error code is returned.
 189  */
 190 int nilfs_init_gccache(struct the_nilfs *nilfs)
 191 {
 192         int loop;
 193
 194         BUG_ON(nilfs->ns_gc_inodes_h);
 195
 196         INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
 197
 198         nilfs->ns_gc_inodes_h =
 199                 kmalloc(sizeof(struct hlist_head) * NILFS_GCINODE_HASH_SIZE,
 200                         GFP_NOFS);
 201         if (nilfs->ns_gc_inodes_h == NULL)
 202                 return -ENOMEM;
 203
 204         for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++)
 205                 INIT_HLIST_HEAD(&nilfs->ns_gc_inodes_h[loop]);
 206         return 0;
 207 }
 208
 209 /*
 210  * nilfs_destroy_gccache() - free gc_inode hash table
 211  * @nilfs - the nilfs
 212  */
 213 void nilfs_destroy_gccache(struct the_nilfs *nilfs)
 214 {
 215         if (nilfs->ns_gc_inodes_h) {
 216                 nilfs_remove_all_gcinode(nilfs);
 217                 kfree(nilfs->ns_gc_inodes_h);
 218                 nilfs->ns_gc_inodes_h = NULL;
 219         }
 220 }
 221
 222 static struct inode *alloc_gcinode(struct the_nilfs *nilfs, ino_t ino,
 223                                    __u64 cno)
 224 {
 225         struct inode *inode;
 226         struct nilfs_inode_info *ii;
 227
 228         inode = nilfs_mdt_new_common(nilfs, NULL, ino, GFP_NOFS, 0);
 229         if (!inode)
 230                 return NULL;
 231
 232         inode->i_op = NULL;
 233         inode->i_fop = NULL;
 234         inode->i_mapping->a_ops = &def_gcinode_aops;
 235
 236         ii = NILFS_I(inode);
 237         ii->i_cno = cno;
 238         ii->i_flags = 0;
 239         ii->i_state = 1 << NILFS_I_GCINODE;
 240         ii->i_bh = NULL;
 241         nilfs_bmap_init_gc(ii->i_bmap);
 242
 243         return inode;
 244 }
 245
 246 static unsigned long ihash(ino_t ino, __u64 cno)
 247 {
 248         return hash_long((unsigned long)((ino << 2) + cno),
 249                          NILFS_GCINODE_HASH_BITS);
 250 }
 251
 252 /*
 253  * nilfs_gc_iget() - find or create gc inode with specified (ino,cno)
 254  */
 255 struct inode *nilfs_gc_iget(struct the_nilfs *nilfs, ino_t ino, __u64 cno)
 256 {
 257         struct hlist_head *head = nilfs->ns_gc_inodes_h + ihash(ino, cno);
 258         struct hlist_node *node;
 259         struct inode *inode;
 260
 261         hlist_for_each_entry(inode, node, head, i_hash) {
 262                 if (inode->i_ino == ino && NILFS_I(inode)->i_cno == cno)
 263                         return inode;
 264         }
 265
 266         inode = alloc_gcinode(nilfs, ino, cno);
 267         if (likely(inode)) {
 268                 hlist_add_head(&inode->i_hash, head);
 269                 list_add(&NILFS_I(inode)->i_dirty, &nilfs->ns_gc_inodes);
 270         }
 271         return inode;
 272 }
 273
 274 /*
 275  * nilfs_clear_gcinode() - clear and free a gc inode
 276  */
 277 void nilfs_clear_gcinode(struct inode *inode)
 278 {
 279         nilfs_mdt_destroy(inode);
 280 }
 281
 282 /*
 283  * nilfs_remove_all_gcinode() - remove all inodes from the_nilfs
 284  */
 285 void nilfs_remove_all_gcinode(struct the_nilfs *nilfs)
 286 {
 287         struct hlist_head *head = nilfs->ns_gc_inodes_h;
 288         struct hlist_node *node, *n;
 289         struct inode *inode;
 290         int loop;
 291
 292         for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++, head++) {
 293                 hlist_for_each_entry_safe(inode, node, n, head, i_hash) {
 294                         hlist_del_init(&inode->i_hash);
 295                         list_del_init(&NILFS_I(inode)->i_dirty);
 296                         nilfs_clear_gcinode(inode); /* might sleep */
 297                 }
 298         }
 299 }