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         memset(btnc, 0, sizeof(*btnc));
  41         INIT_RADIX_TREE(&btnc->page_tree, GFP_ATOMIC);
  42         spin_lock_init(&btnc->tree_lock);
  43         INIT_LIST_HEAD(&btnc->private_list);
  44         spin_lock_init(&btnc->private_lock);
  45
  46         spin_lock_init(&btnc->i_mmap_lock);
  47         INIT_RAW_PRIO_TREE_ROOT(&btnc->i_mmap);
  48         INIT_LIST_HEAD(&btnc->i_mmap_nonlinear);
  49 }
  50
  51 static const struct address_space_operations def_btnode_aops = {
  52         .sync_page              = block_sync_page,
  53 };
  54
  55 void nilfs_btnode_cache_init(struct address_space *btnc,
  56                              struct backing_dev_info *bdi)
  57 {
  58         btnc->host = NULL;  /* can safely set to host inode ? */
  59         btnc->flags = 0;
  60         mapping_set_gfp_mask(btnc, GFP_NOFS);
  61         btnc->assoc_mapping = NULL;
  62         btnc->backing_dev_info = bdi;
  63         btnc->a_ops = &def_btnode_aops;
  64 }
  65
  66 void nilfs_btnode_cache_clear(struct address_space *btnc)
  67 {
  68         invalidate_mapping_pages(btnc, 0, -1);
  69         truncate_inode_pages(btnc, 0);
  70 }
  71
  72 struct buffer_head *
  73 nilfs_btnode_create_block(struct address_space *btnc, __u64 blocknr)
  74 {
  75         struct inode *inode = NILFS_BTNC_I(btnc);
  76         struct buffer_head *bh;
  77
  78         bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
  79         if (unlikely(!bh))
  80                 return NULL;
  81
  82         if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
  83                      buffer_dirty(bh))) {
  84                 brelse(bh);
  85                 BUG();
  86         }
  87         memset(bh->b_data, 0, 1 << inode->i_blkbits);
  88         bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
  89         bh->b_blocknr = blocknr;
  90         set_buffer_mapped(bh);
  91         set_buffer_uptodate(bh);
  92
  93         unlock_page(bh->b_page);
  94         page_cache_release(bh->b_page);
  95         return bh;
  96 }
  97
  98 int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
  99                               sector_t pblocknr, int mode,
 100                               struct buffer_head **pbh, sector_t *submit_ptr)
 101 {
 102         struct buffer_head *bh;
 103         struct inode *inode = NILFS_BTNC_I(btnc);
 104         struct page *page;
 105         int err;
 106
 107         bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
 108         if (unlikely(!bh))
 109                 return -ENOMEM;
 110
 111         err = -EEXIST; /* internal code */
 112         page = bh->b_page;
 113
 114         if (buffer_uptodate(bh) || buffer_dirty(bh))
 115                 goto found;
 116
 117         if (pblocknr == 0) {
 118                 pblocknr = blocknr;
 119                 if (inode->i_ino != NILFS_DAT_INO) {
 120                         struct inode *dat =
 121                                 nilfs_dat_inode(NILFS_I_NILFS(inode));
 122
 123                         /* blocknr is a virtual block number */
 124                         err = nilfs_dat_translate(dat, blocknr, &pblocknr);
 125                         if (unlikely(err)) {
 126                                 brelse(bh);
 127                                 goto out_locked;
 128                         }
 129                 }
 130         }
 131
 132         if (mode == READA) {
 133                 if (pblocknr != *submit_ptr + 1 || !trylock_buffer(bh)) {
 134                         err = -EBUSY; /* internal code */
 135                         brelse(bh);
 136                         goto out_locked;
 137                 }
 138         } else { /* mode == READ */
 139                 lock_buffer(bh);
 140         }
 141         if (buffer_uptodate(bh)) {
 142                 unlock_buffer(bh);
 143                 err = -EEXIST; /* internal code */
 144                 goto found;
 145         }
 146         set_buffer_mapped(bh);
 147         bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
 148         bh->b_blocknr = pblocknr; /* set block address for read */
 149         bh->b_end_io = end_buffer_read_sync;
 150         get_bh(bh);
 151         submit_bh(mode, bh);
 152         bh->b_blocknr = blocknr; /* set back to the given block address */
 153         *submit_ptr = pblocknr;
 154         err = 0;
 155 found:
 156         *pbh = bh;
 157
 158 out_locked:
 159         unlock_page(page);
 160         page_cache_release(page);
 161         return err;
 162 }
 163
 164 /**
 165  * nilfs_btnode_delete - delete B-tree node buffer
 166  * @bh: buffer to be deleted
 167  *
 168  * nilfs_btnode_delete() invalidates the specified buffer and delete the page
 169  * including the buffer if the page gets unbusy.
 170  */
 171 void nilfs_btnode_delete(struct buffer_head *bh)
 172 {
 173         struct address_space *mapping;
 174         struct page *page = bh->b_page;
 175         pgoff_t index = page_index(page);
 176         int still_dirty;
 177
 178         page_cache_get(page);
 179         lock_page(page);
 180         wait_on_page_writeback(page);
 181
 182         nilfs_forget_buffer(bh);
 183         still_dirty = PageDirty(page);
 184         mapping = page->mapping;
 185         unlock_page(page);
 186         page_cache_release(page);
 187
 188         if (!still_dirty && mapping)
 189                 invalidate_inode_pages2_range(mapping, index, index);
 190 }
 191
 192 /**
 193  * nilfs_btnode_prepare_change_key
 194  *  prepare to move contents of the block for old key to one of new key.
 195  *  the old buffer will not be removed, but might be reused for new buffer.
 196  *  it might return -ENOMEM because of memory allocation errors,
 197  *  and might return -EIO because of disk read errors.
 198  */
 199 int nilfs_btnode_prepare_change_key(struct address_space *btnc,
 200                                     struct nilfs_btnode_chkey_ctxt *ctxt)
 201 {
 202         struct buffer_head *obh, *nbh;
 203         struct inode *inode = NILFS_BTNC_I(btnc);
 204         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 205         int err;
 206
 207         if (oldkey == newkey)
 208                 return 0;
 209
 210         obh = ctxt->bh;
 211         ctxt->newbh = NULL;
 212
 213         if (inode->i_blkbits == PAGE_CACHE_SHIFT) {
 214                 lock_page(obh->b_page);
 215                 /*
 216                  * We cannot call radix_tree_preload for the kernels older
 217                  * than 2.6.23, because it is not exported for modules.
 218                  */
 219 retry:
 220                 err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
 221                 if (err)
 222                         goto failed_unlock;
 223                 /* BUG_ON(oldkey != obh->b_page->index); */
 224                 if (unlikely(oldkey != obh->b_page->index))
 225                         NILFS_PAGE_BUG(obh->b_page,
 226                                        "invalid oldkey %lld (newkey=%lld)",
 227                                        (unsigned long long)oldkey,
 228                                        (unsigned long long)newkey);
 229
 230                 spin_lock_irq(&btnc->tree_lock);
 231                 err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);
 232                 spin_unlock_irq(&btnc->tree_lock);
 233                 /*
 234                  * Note: page->index will not change to newkey until
 235                  * nilfs_btnode_commit_change_key() will be called.
 236                  * To protect the page in intermediate state, the page lock
 237                  * is held.
 238                  */
 239                 radix_tree_preload_end();
 240                 if (!err)
 241                         return 0;
 242                 else if (err != -EEXIST)
 243                         goto failed_unlock;
 244
 245                 err = invalidate_inode_pages2_range(btnc, newkey, newkey);
 246                 if (!err)
 247                         goto retry;
 248                 /* fallback to copy mode */
 249                 unlock_page(obh->b_page);
 250         }
 251
 252         nbh = nilfs_btnode_create_block(btnc, newkey);
 253         if (!nbh)
 254                 return -ENOMEM;
 255
 256         BUG_ON(nbh == obh);
 257         ctxt->newbh = nbh;
 258         return 0;
 259
 260  failed_unlock:
 261         unlock_page(obh->b_page);
 262         return err;
 263 }
 264
 265 /**
 266  * nilfs_btnode_commit_change_key
 267  *  commit the change_key operation prepared by prepare_change_key().
 268  */
 269 void nilfs_btnode_commit_change_key(struct address_space *btnc,
 270                                     struct nilfs_btnode_chkey_ctxt *ctxt)
 271 {
 272         struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
 273         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 274         struct page *opage;
 275
 276         if (oldkey == newkey)
 277                 return;
 278
 279         if (nbh == NULL) {      /* blocksize == pagesize */
 280                 opage = obh->b_page;
 281                 if (unlikely(oldkey != opage->index))
 282                         NILFS_PAGE_BUG(opage,
 283                                        "invalid oldkey %lld (newkey=%lld)",
 284                                        (unsigned long long)oldkey,
 285                                        (unsigned long long)newkey);
 286                 nilfs_btnode_mark_dirty(obh);
 287
 288                 spin_lock_irq(&btnc->tree_lock);
 289                 radix_tree_delete(&btnc->page_tree, oldkey);
 290                 radix_tree_tag_set(&btnc->page_tree, newkey,
 291                                    PAGECACHE_TAG_DIRTY);
 292                 spin_unlock_irq(&btnc->tree_lock);
 293
 294                 opage->index = obh->b_blocknr = newkey;
 295                 unlock_page(opage);
 296         } else {
 297                 nilfs_copy_buffer(nbh, obh);
 298                 nilfs_btnode_mark_dirty(nbh);
 299
 300                 nbh->b_blocknr = newkey;
 301                 ctxt->bh = nbh;
 302                 nilfs_btnode_delete(obh); /* will decrement bh->b_count */
 303         }
 304 }
 305
 306 /**
 307  * nilfs_btnode_abort_change_key
 308  *  abort the change_key operation prepared by prepare_change_key().
 309  */
 310 void nilfs_btnode_abort_change_key(struct address_space *btnc,
 311                                    struct nilfs_btnode_chkey_ctxt *ctxt)
 312 {
 313         struct buffer_head *nbh = ctxt->newbh;
 314         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 315
 316         if (oldkey == newkey)
 317                 return;
 318
 319         if (nbh == NULL) {      /* blocksize == pagesize */
 320                 spin_lock_irq(&btnc->tree_lock);
 321                 radix_tree_delete(&btnc->page_tree, newkey);
 322                 spin_unlock_irq(&btnc->tree_lock);
 323                 unlock_page(ctxt->bh->b_page);
 324         } else
 325                 brelse(nbh);
 326 }