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