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   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, struct buffer_head **pbh)
 100 {
 101         struct buffer_head *bh;
 102         struct inode *inode = NILFS_BTNC_I(btnc);
 103         int err;
 104
 105         bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
 106         if (unlikely(!bh))
 107                 return -ENOMEM;
 108
 109         err = -EEXIST; /* internal code */
 110
 111         if (buffer_uptodate(bh) || buffer_dirty(bh))
 112                 goto found;
 113
 114         if (pblocknr == 0) {
 115                 pblocknr = blocknr;
 116                 if (inode->i_ino != NILFS_DAT_INO) {
 117                         struct inode *dat =
 118                                 nilfs_dat_inode(NILFS_I_NILFS(inode));
 119
 120                         /* blocknr is a virtual block number */
 121                         err = nilfs_dat_translate(dat, blocknr, &pblocknr);
 122                         if (unlikely(err)) {
 123                                 brelse(bh);
 124                                 goto out_locked;
 125                         }
 126                 }
 127         }
 128         lock_buffer(bh);
 129         if (buffer_uptodate(bh)) {
 130                 unlock_buffer(bh);
 131                 err = -EEXIST; /* internal code */
 132                 goto found;
 133         }
 134         set_buffer_mapped(bh);
 135         bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
 136         bh->b_blocknr = pblocknr; /* set block address for read */
 137         bh->b_end_io = end_buffer_read_sync;
 138         get_bh(bh);
 139         submit_bh(READ, bh);
 140         bh->b_blocknr = blocknr; /* set back to the given block address */
 141         err = 0;
 142 found:
 143         *pbh = bh;
 144
 145 out_locked:
 146         unlock_page(bh->b_page);
 147         page_cache_release(bh->b_page);
 148         return err;
 149 }
 150
 151 /**
 152  * nilfs_btnode_delete - delete B-tree node buffer
 153  * @bh: buffer to be deleted
 154  *
 155  * nilfs_btnode_delete() invalidates the specified buffer and delete the page
 156  * including the buffer if the page gets unbusy.
 157  */
 158 void nilfs_btnode_delete(struct buffer_head *bh)
 159 {
 160         struct address_space *mapping;
 161         struct page *page = bh->b_page;
 162         pgoff_t index = page_index(page);
 163         int still_dirty;
 164
 165         page_cache_get(page);
 166         lock_page(page);
 167         wait_on_page_writeback(page);
 168
 169         nilfs_forget_buffer(bh);
 170         still_dirty = PageDirty(page);
 171         mapping = page->mapping;
 172         unlock_page(page);
 173         page_cache_release(page);
 174
 175         if (!still_dirty && mapping)
 176                 invalidate_inode_pages2_range(mapping, index, index);
 177 }
 178
 179 /**
 180  * nilfs_btnode_prepare_change_key
 181  *  prepare to move contents of the block for old key to one of new key.
 182  *  the old buffer will not be removed, but might be reused for new buffer.
 183  *  it might return -ENOMEM because of memory allocation errors,
 184  *  and might return -EIO because of disk read errors.
 185  */
 186 int nilfs_btnode_prepare_change_key(struct address_space *btnc,
 187                                     struct nilfs_btnode_chkey_ctxt *ctxt)
 188 {
 189         struct buffer_head *obh, *nbh;
 190         struct inode *inode = NILFS_BTNC_I(btnc);
 191         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 192         int err;
 193
 194         if (oldkey == newkey)
 195                 return 0;
 196
 197         obh = ctxt->bh;
 198         ctxt->newbh = NULL;
 199
 200         if (inode->i_blkbits == PAGE_CACHE_SHIFT) {
 201                 lock_page(obh->b_page);
 202                 /*
 203                  * We cannot call radix_tree_preload for the kernels older
 204                  * than 2.6.23, because it is not exported for modules.
 205                  */
 206 retry:
 207                 err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
 208                 if (err)
 209                         goto failed_unlock;
 210                 /* BUG_ON(oldkey != obh->b_page->index); */
 211                 if (unlikely(oldkey != obh->b_page->index))
 212                         NILFS_PAGE_BUG(obh->b_page,
 213                                        "invalid oldkey %lld (newkey=%lld)",
 214                                        (unsigned long long)oldkey,
 215                                        (unsigned long long)newkey);
 216
 217                 spin_lock_irq(&btnc->tree_lock);
 218                 err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);
 219                 spin_unlock_irq(&btnc->tree_lock);
 220                 /*
 221                  * Note: page->index will not change to newkey until
 222                  * nilfs_btnode_commit_change_key() will be called.
 223                  * To protect the page in intermediate state, the page lock
 224                  * is held.
 225                  */
 226                 radix_tree_preload_end();
 227                 if (!err)
 228                         return 0;
 229                 else if (err != -EEXIST)
 230                         goto failed_unlock;
 231
 232                 err = invalidate_inode_pages2_range(btnc, newkey, newkey);
 233                 if (!err)
 234                         goto retry;
 235                 /* fallback to copy mode */
 236                 unlock_page(obh->b_page);
 237         }
 238
 239         nbh = nilfs_btnode_create_block(btnc, newkey);
 240         if (!nbh)
 241                 return -ENOMEM;
 242
 243         BUG_ON(nbh == obh);
 244         ctxt->newbh = nbh;
 245         return 0;
 246
 247  failed_unlock:
 248         unlock_page(obh->b_page);
 249         return err;
 250 }
 251
 252 /**
 253  * nilfs_btnode_commit_change_key
 254  *  commit the change_key operation prepared by prepare_change_key().
 255  */
 256 void nilfs_btnode_commit_change_key(struct address_space *btnc,
 257                                     struct nilfs_btnode_chkey_ctxt *ctxt)
 258 {
 259         struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
 260         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 261         struct page *opage;
 262
 263         if (oldkey == newkey)
 264                 return;
 265
 266         if (nbh == NULL) {      /* blocksize == pagesize */
 267                 opage = obh->b_page;
 268                 if (unlikely(oldkey != opage->index))
 269                         NILFS_PAGE_BUG(opage,
 270                                        "invalid oldkey %lld (newkey=%lld)",
 271                                        (unsigned long long)oldkey,
 272                                        (unsigned long long)newkey);
 273                 nilfs_btnode_mark_dirty(obh);
 274
 275                 spin_lock_irq(&btnc->tree_lock);
 276                 radix_tree_delete(&btnc->page_tree, oldkey);
 277                 radix_tree_tag_set(&btnc->page_tree, newkey,
 278                                    PAGECACHE_TAG_DIRTY);
 279                 spin_unlock_irq(&btnc->tree_lock);
 280
 281                 opage->index = obh->b_blocknr = newkey;
 282                 unlock_page(opage);
 283         } else {
 284                 nilfs_copy_buffer(nbh, obh);
 285                 nilfs_btnode_mark_dirty(nbh);
 286
 287                 nbh->b_blocknr = newkey;
 288                 ctxt->bh = nbh;
 289                 nilfs_btnode_delete(obh); /* will decrement bh->b_count */
 290         }
 291 }
 292
 293 /**
 294  * nilfs_btnode_abort_change_key
 295  *  abort the change_key operation prepared by prepare_change_key().
 296  */
 297 void nilfs_btnode_abort_change_key(struct address_space *btnc,
 298                                    struct nilfs_btnode_chkey_ctxt *ctxt)
 299 {
 300         struct buffer_head *nbh = ctxt->newbh;
 301         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 302
 303         if (oldkey == newkey)
 304                 return;
 305
 306         if (nbh == NULL) {      /* blocksize == pagesize */
 307                 spin_lock_irq(&btnc->tree_lock);
 308                 radix_tree_delete(&btnc->page_tree, newkey);
 309                 spin_unlock_irq(&btnc->tree_lock);
 310                 unlock_page(ctxt->bh->b_page);
 311         } else
 312                 brelse(nbh);
 313 }