fs/nilfs2/btnode.c

   1 /*
   2  * btnode.c - NILFS B-tree node cache
   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  * This file was originally written by Seiji Kihara <kihara@osrg.net>
  21  * and fully revised by Ryusuke Konishi <ryusuke@osrg.net> for
  22  * stabilization and simplification.
  23  *
  24  */
  25
  26 #include <linux/types.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/mm.h>
  29 #include <linux/backing-dev.h>
  30 #include <linux/gfp.h>
  31 #include "nilfs.h"
  32 #include "mdt.h"
  33 #include "dat.h"
  34 #include "page.h"
  35 #include "btnode.h"
  36
  37
  38 void nilfs_btnode_cache_init_once(struct address_space *btnc)
  39 {
  40         nilfs_mapping_init_once(btnc);
  41 }
  42
  43 static const struct address_space_operations def_btnode_aops = {
  44         .sync_page              = block_sync_page,
  45 };
  46
  47 void nilfs_btnode_cache_init(struct address_space *btnc,
  48                              struct backing_dev_info *bdi)
  49 {
  50         nilfs_mapping_init(btnc, bdi, &def_btnode_aops);
  51 }
  52
  53 void nilfs_btnode_cache_clear(struct address_space *btnc)
  54 {
  55         invalidate_mapping_pages(btnc, 0, -1);
  56         truncate_inode_pages(btnc, 0);
  57 }
  58
  59 struct buffer_head *
  60 nilfs_btnode_create_block(struct address_space *btnc, __u64 blocknr)
  61 {
  62         struct inode *inode = NILFS_BTNC_I(btnc);
  63         struct buffer_head *bh;
  64
  65         bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
  66         if (unlikely(!bh))
  67                 return NULL;
  68
  69         if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
  70                      buffer_dirty(bh))) {
  71                 brelse(bh);
  72                 BUG();
  73         }
  74         memset(bh->b_data, 0, 1 << inode->i_blkbits);
  75         bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
  76         bh->b_blocknr = blocknr;
  77         set_buffer_mapped(bh);
  78         set_buffer_uptodate(bh);
  79
  80         unlock_page(bh->b_page);
  81         page_cache_release(bh->b_page);
  82         return bh;
  83 }
  84
  85 int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
  86                               sector_t pblocknr, int mode,
  87                               struct buffer_head **pbh, sector_t *submit_ptr)
  88 {
  89         struct buffer_head *bh;
  90         struct inode *inode = NILFS_BTNC_I(btnc);
  91         struct page *page;
  92         int err;
  93
  94         bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
  95         if (unlikely(!bh))
  96                 return -ENOMEM;
  97
  98         err = -EEXIST; /* internal code */
  99         page = bh->b_page;
 100
 101         if (buffer_uptodate(bh) || buffer_dirty(bh))
 102                 goto found;
 103
 104         if (pblocknr == 0) {
 105                 pblocknr = blocknr;
 106                 if (inode->i_ino != NILFS_DAT_INO) {
 107                         struct inode *dat = NILFS_I_NILFS(inode)->ns_dat;
 108
 109                         /* blocknr is a virtual block number */
 110                         err = nilfs_dat_translate(dat, blocknr, &pblocknr);
 111                         if (unlikely(err)) {
 112                                 brelse(bh);
 113                                 goto out_locked;
 114                         }
 115                 }
 116         }
 117
 118         if (mode == READA) {
 119                 if (pblocknr != *submit_ptr + 1 || !trylock_buffer(bh)) {
 120                         err = -EBUSY; /* internal code */
 121                         brelse(bh);
 122                         goto out_locked;
 123                 }
 124         } else { /* mode == READ */
 125                 lock_buffer(bh);
 126         }
 127         if (buffer_uptodate(bh)) {
 128                 unlock_buffer(bh);
 129                 err = -EEXIST; /* internal code */
 130                 goto found;
 131         }
 132         set_buffer_mapped(bh);
 133         bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
 134         bh->b_blocknr = pblocknr; /* set block address for read */
 135         bh->b_end_io = end_buffer_read_sync;
 136         get_bh(bh);
 137         submit_bh(mode, bh);
 138         bh->b_blocknr = blocknr; /* set back to the given block address */
 139         *submit_ptr = pblocknr;
 140         err = 0;
 141 found:
 142         *pbh = bh;
 143
 144 out_locked:
 145         unlock_page(page);
 146         page_cache_release(page);
 147         return err;
 148 }
 149
 150 /**
 151  * nilfs_btnode_delete - delete B-tree node buffer
 152  * @bh: buffer to be deleted
 153  *
 154  * nilfs_btnode_delete() invalidates the specified buffer and delete the page
 155  * including the buffer if the page gets unbusy.
 156  */
 157 void nilfs_btnode_delete(struct buffer_head *bh)
 158 {
 159         struct address_space *mapping;
 160         struct page *page = bh->b_page;
 161         pgoff_t index = page_index(page);
 162         int still_dirty;
 163
 164         page_cache_get(page);
 165         lock_page(page);
 166         wait_on_page_writeback(page);
 167
 168         nilfs_forget_buffer(bh);
 169         still_dirty = PageDirty(page);
 170         mapping = page->mapping;
 171         unlock_page(page);
 172         page_cache_release(page);
 173
 174         if (!still_dirty && mapping)
 175                 invalidate_inode_pages2_range(mapping, index, index);
 176 }
 177
 178 /**
 179  * nilfs_btnode_prepare_change_key
 180  *  prepare to move contents of the block for old key to one of new key.
 181  *  the old buffer will not be removed, but might be reused for new buffer.
 182  *  it might return -ENOMEM because of memory allocation errors,
 183  *  and might return -EIO because of disk read errors.
 184  */
 185 int nilfs_btnode_prepare_change_key(struct address_space *btnc,
 186                                     struct nilfs_btnode_chkey_ctxt *ctxt)
 187 {
 188         struct buffer_head *obh, *nbh;
 189         struct inode *inode = NILFS_BTNC_I(btnc);
 190         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 191         int err;
 192
 193         if (oldkey == newkey)
 194                 return 0;
 195
 196         obh = ctxt->bh;
 197         ctxt->newbh = NULL;
 198
 199         if (inode->i_blkbits == PAGE_CACHE_SHIFT) {
 200                 lock_page(obh->b_page);
 201                 /*
 202                  * We cannot call radix_tree_preload for the kernels older
 203                  * than 2.6.23, because it is not exported for modules.
 204                  */
 205 retry:
 206                 err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
 207                 if (err)
 208                         goto failed_unlock;
 209                 /* BUG_ON(oldkey != obh->b_page->index); */
 210                 if (unlikely(oldkey != obh->b_page->index))
 211                         NILFS_PAGE_BUG(obh->b_page,
 212                                        "invalid oldkey %lld (newkey=%lld)",
 213                                        (unsigned long long)oldkey,
 214                                        (unsigned long long)newkey);
 215
 216                 spin_lock_irq(&btnc->tree_lock);
 217                 err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);
 218                 spin_unlock_irq(&btnc->tree_lock);
 219                 /*
 220                  * Note: page->index will not change to newkey until
 221                  * nilfs_btnode_commit_change_key() will be called.
 222                  * To protect the page in intermediate state, the page lock
 223                  * is held.
 224                  */
 225                 radix_tree_preload_end();
 226                 if (!err)
 227                         return 0;
 228                 else if (err != -EEXIST)
 229                         goto failed_unlock;
 230
 231                 err = invalidate_inode_pages2_range(btnc, newkey, newkey);
 232                 if (!err)
 233                         goto retry;
 234                 /* fallback to copy mode */
 235                 unlock_page(obh->b_page);
 236         }
 237
 238         nbh = nilfs_btnode_create_block(btnc, newkey);
 239         if (!nbh)
 240                 return -ENOMEM;
 241
 242         BUG_ON(nbh == obh);
 243         ctxt->newbh = nbh;
 244         return 0;
 245
 246  failed_unlock:
 247         unlock_page(obh->b_page);
 248         return err;
 249 }
 250
 251 /**
 252  * nilfs_btnode_commit_change_key
 253  *  commit the change_key operation prepared by prepare_change_key().
 254  */
 255 void nilfs_btnode_commit_change_key(struct address_space *btnc,
 256                                     struct nilfs_btnode_chkey_ctxt *ctxt)
 257 {
 258         struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
 259         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 260         struct page *opage;
 261
 262         if (oldkey == newkey)
 263                 return;
 264
 265         if (nbh == NULL) {      /* blocksize == pagesize */
 266                 opage = obh->b_page;
 267                 if (unlikely(oldkey != opage->index))
 268                         NILFS_PAGE_BUG(opage,
 269                                        "invalid oldkey %lld (newkey=%lld)",
 270                                        (unsigned long long)oldkey,
 271                                        (unsigned long long)newkey);
 272                 nilfs_btnode_mark_dirty(obh);
 273
 274                 spin_lock_irq(&btnc->tree_lock);
 275                 radix_tree_delete(&btnc->page_tree, oldkey);
 276                 radix_tree_tag_set(&btnc->page_tree, newkey,
 277                                    PAGECACHE_TAG_DIRTY);
 278                 spin_unlock_irq(&btnc->tree_lock);
 279
 280                 opage->index = obh->b_blocknr = newkey;
 281                 unlock_page(opage);
 282         } else {
 283                 nilfs_copy_buffer(nbh, obh);
 284                 nilfs_btnode_mark_dirty(nbh);
 285
 286                 nbh->b_blocknr = newkey;
 287                 ctxt->bh = nbh;
 288                 nilfs_btnode_delete(obh); /* will decrement bh->b_count */
 289         }
 290 }
 291
 292 /**
 293  * nilfs_btnode_abort_change_key
 294  *  abort the change_key operation prepared by prepare_change_key().
 295  */
 296 void nilfs_btnode_abort_change_key(struct address_space *btnc,
 297                                    struct nilfs_btnode_chkey_ctxt *ctxt)
 298 {
 299         struct buffer_head *nbh = ctxt->newbh;
 300         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 301
 302         if (oldkey == newkey)
 303                 return;
 304
 305         if (nbh == NULL) {      /* blocksize == pagesize */
 306                 spin_lock_irq(&btnc->tree_lock);
 307                 radix_tree_delete(&btnc->page_tree, newkey);
 308                 spin_unlock_irq(&btnc->tree_lock);
 309                 unlock_page(ctxt->bh->b_page);
 310         } else
 311                 brelse(nbh);
 312 }