linux/fs/nilfs2/mdt.c
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   1/*
   2 * mdt.c - meta data file for NILFS
   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 Ryusuke Konishi <ryusuke@osrg.net>
  21 */
  22
  23#include <linux/buffer_head.h>
  24#include <linux/mpage.h>
  25#include <linux/mm.h>
  26#include <linux/writeback.h>
  27#include <linux/backing-dev.h>
  28#include <linux/swap.h>
  29#include <linux/slab.h>
  30#include "nilfs.h"
  31#include "btnode.h"
  32#include "segment.h"
  33#include "page.h"
  34#include "mdt.h"
  35
  36
  37#define NILFS_MDT_MAX_RA_BLOCKS         (16 - 1)
  38
  39
  40static int
  41nilfs_mdt_insert_new_block(struct inode *inode, unsigned long block,
  42                           struct buffer_head *bh,
  43                           void (*init_block)(struct inode *,
  44                                              struct buffer_head *, void *))
  45{
  46        struct nilfs_inode_info *ii = NILFS_I(inode);
  47        void *kaddr;
  48        int ret;
  49
  50        /* Caller exclude read accesses using page lock */
  51
  52        /* set_buffer_new(bh); */
  53        bh->b_blocknr = 0;
  54
  55        ret = nilfs_bmap_insert(ii->i_bmap, block, (unsigned long)bh);
  56        if (unlikely(ret))
  57                return ret;
  58
  59        set_buffer_mapped(bh);
  60
  61        kaddr = kmap_atomic(bh->b_page);
  62        memset(kaddr + bh_offset(bh), 0, 1 << inode->i_blkbits);
  63        if (init_block)
  64                init_block(inode, bh, kaddr);
  65        flush_dcache_page(bh->b_page);
  66        kunmap_atomic(kaddr);
  67
  68        set_buffer_uptodate(bh);
  69        mark_buffer_dirty(bh);
  70        nilfs_mdt_mark_dirty(inode);
  71        return 0;
  72}
  73
  74static int nilfs_mdt_create_block(struct inode *inode, unsigned long block,
  75                                  struct buffer_head **out_bh,
  76                                  void (*init_block)(struct inode *,
  77                                                     struct buffer_head *,
  78                                                     void *))
  79{
  80        struct super_block *sb = inode->i_sb;
  81        struct nilfs_transaction_info ti;
  82        struct buffer_head *bh;
  83        int err;
  84
  85        nilfs_transaction_begin(sb, &ti, 0);
  86
  87        err = -ENOMEM;
  88        bh = nilfs_grab_buffer(inode, inode->i_mapping, block, 0);
  89        if (unlikely(!bh))
  90                goto failed_unlock;
  91
  92        err = -EEXIST;
  93        if (buffer_uptodate(bh))
  94                goto failed_bh;
  95
  96        wait_on_buffer(bh);
  97        if (buffer_uptodate(bh))
  98                goto failed_bh;
  99
 100        bh->b_bdev = sb->s_bdev;
 101        err = nilfs_mdt_insert_new_block(inode, block, bh, init_block);
 102        if (likely(!err)) {
 103                get_bh(bh);
 104                *out_bh = bh;
 105        }
 106
 107 failed_bh:
 108        unlock_page(bh->b_page);
 109        page_cache_release(bh->b_page);
 110        brelse(bh);
 111
 112 failed_unlock:
 113        if (likely(!err))
 114                err = nilfs_transaction_commit(sb);
 115        else
 116                nilfs_transaction_abort(sb);
 117
 118        return err;
 119}
 120
 121static int
 122nilfs_mdt_submit_block(struct inode *inode, unsigned long blkoff,
 123                       int mode, struct buffer_head **out_bh)
 124{
 125        struct buffer_head *bh;
 126        __u64 blknum = 0;
 127        int ret = -ENOMEM;
 128
 129        bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
 130        if (unlikely(!bh))
 131                goto failed;
 132
 133        ret = -EEXIST; /* internal code */
 134        if (buffer_uptodate(bh))
 135                goto out;
 136
 137        if (mode == READA) {
 138                if (!trylock_buffer(bh)) {
 139                        ret = -EBUSY;
 140                        goto failed_bh;
 141                }
 142        } else /* mode == READ */
 143                lock_buffer(bh);
 144
 145        if (buffer_uptodate(bh)) {
 146                unlock_buffer(bh);
 147                goto out;
 148        }
 149
 150        ret = nilfs_bmap_lookup(NILFS_I(inode)->i_bmap, blkoff, &blknum);
 151        if (unlikely(ret)) {
 152                unlock_buffer(bh);
 153                goto failed_bh;
 154        }
 155        map_bh(bh, inode->i_sb, (sector_t)blknum);
 156
 157        bh->b_end_io = end_buffer_read_sync;
 158        get_bh(bh);
 159        submit_bh(mode, bh);
 160        ret = 0;
 161 out:
 162        get_bh(bh);
 163        *out_bh = bh;
 164
 165 failed_bh:
 166        unlock_page(bh->b_page);
 167        page_cache_release(bh->b_page);
 168        brelse(bh);
 169 failed:
 170        return ret;
 171}
 172
 173static int nilfs_mdt_read_block(struct inode *inode, unsigned long block,
 174                                int readahead, struct buffer_head **out_bh)
 175{
 176        struct buffer_head *first_bh, *bh;
 177        unsigned long blkoff;
 178        int i, nr_ra_blocks = NILFS_MDT_MAX_RA_BLOCKS;
 179        int err;
 180
 181        err = nilfs_mdt_submit_block(inode, block, READ, &first_bh);
 182        if (err == -EEXIST) /* internal code */
 183                goto out;
 184
 185        if (unlikely(err))
 186                goto failed;
 187
 188        if (readahead) {
 189                blkoff = block + 1;
 190                for (i = 0; i < nr_ra_blocks; i++, blkoff++) {
 191                        err = nilfs_mdt_submit_block(inode, blkoff, READA, &bh);
 192                        if (likely(!err || err == -EEXIST))
 193                                brelse(bh);
 194                        else if (err != -EBUSY)
 195                                break;
 196                                /* abort readahead if bmap lookup failed */
 197                        if (!buffer_locked(first_bh))
 198                                goto out_no_wait;
 199                }
 200        }
 201
 202        wait_on_buffer(first_bh);
 203
 204 out_no_wait:
 205        err = -EIO;
 206        if (!buffer_uptodate(first_bh))
 207                goto failed_bh;
 208 out:
 209        *out_bh = first_bh;
 210        return 0;
 211
 212 failed_bh:
 213        brelse(first_bh);
 214 failed:
 215        return err;
 216}
 217
 218/**
 219 * nilfs_mdt_get_block - read or create a buffer on meta data file.
 220 * @inode: inode of the meta data file
 221 * @blkoff: block offset
 222 * @create: create flag
 223 * @init_block: initializer used for newly allocated block
 224 * @out_bh: output of a pointer to the buffer_head
 225 *
 226 * nilfs_mdt_get_block() looks up the specified buffer and tries to create
 227 * a new buffer if @create is not zero.  On success, the returned buffer is
 228 * assured to be either existing or formatted using a buffer lock on success.
 229 * @out_bh is substituted only when zero is returned.
 230 *
 231 * Return Value: On success, it returns 0. On error, the following negative
 232 * error code is returned.
 233 *
 234 * %-ENOMEM - Insufficient memory available.
 235 *
 236 * %-EIO - I/O error
 237 *
 238 * %-ENOENT - the specified block does not exist (hole block)
 239 *
 240 * %-EROFS - Read only filesystem (for create mode)
 241 */
 242int nilfs_mdt_get_block(struct inode *inode, unsigned long blkoff, int create,
 243                        void (*init_block)(struct inode *,
 244                                           struct buffer_head *, void *),
 245                        struct buffer_head **out_bh)
 246{
 247        int ret;
 248
 249        /* Should be rewritten with merging nilfs_mdt_read_block() */
 250 retry:
 251        ret = nilfs_mdt_read_block(inode, blkoff, !create, out_bh);
 252        if (!create || ret != -ENOENT)
 253                return ret;
 254
 255        ret = nilfs_mdt_create_block(inode, blkoff, out_bh, init_block);
 256        if (unlikely(ret == -EEXIST)) {
 257                /* create = 0; */  /* limit read-create loop retries */
 258                goto retry;
 259        }
 260        return ret;
 261}
 262
 263/**
 264 * nilfs_mdt_delete_block - make a hole on the meta data file.
 265 * @inode: inode of the meta data file
 266 * @block: block offset
 267 *
 268 * Return Value: On success, zero is returned.
 269 * On error, one of the following negative error code is returned.
 270 *
 271 * %-ENOMEM - Insufficient memory available.
 272 *
 273 * %-EIO - I/O error
 274 */
 275int nilfs_mdt_delete_block(struct inode *inode, unsigned long block)
 276{
 277        struct nilfs_inode_info *ii = NILFS_I(inode);
 278        int err;
 279
 280        err = nilfs_bmap_delete(ii->i_bmap, block);
 281        if (!err || err == -ENOENT) {
 282                nilfs_mdt_mark_dirty(inode);
 283                nilfs_mdt_forget_block(inode, block);
 284        }
 285        return err;
 286}
 287
 288/**
 289 * nilfs_mdt_forget_block - discard dirty state and try to remove the page
 290 * @inode: inode of the meta data file
 291 * @block: block offset
 292 *
 293 * nilfs_mdt_forget_block() clears a dirty flag of the specified buffer, and
 294 * tries to release the page including the buffer from a page cache.
 295 *
 296 * Return Value: On success, 0 is returned. On error, one of the following
 297 * negative error code is returned.
 298 *
 299 * %-EBUSY - page has an active buffer.
 300 *
 301 * %-ENOENT - page cache has no page addressed by the offset.
 302 */
 303int nilfs_mdt_forget_block(struct inode *inode, unsigned long block)
 304{
 305        pgoff_t index = (pgoff_t)block >>
 306                (PAGE_CACHE_SHIFT - inode->i_blkbits);
 307        struct page *page;
 308        unsigned long first_block;
 309        int ret = 0;
 310        int still_dirty;
 311
 312        page = find_lock_page(inode->i_mapping, index);
 313        if (!page)
 314                return -ENOENT;
 315
 316        wait_on_page_writeback(page);
 317
 318        first_block = (unsigned long)index <<
 319                (PAGE_CACHE_SHIFT - inode->i_blkbits);
 320        if (page_has_buffers(page)) {
 321                struct buffer_head *bh;
 322
 323                bh = nilfs_page_get_nth_block(page, block - first_block);
 324                nilfs_forget_buffer(bh);
 325        }
 326        still_dirty = PageDirty(page);
 327        unlock_page(page);
 328        page_cache_release(page);
 329
 330        if (still_dirty ||
 331            invalidate_inode_pages2_range(inode->i_mapping, index, index) != 0)
 332                ret = -EBUSY;
 333        return ret;
 334}
 335
 336/**
 337 * nilfs_mdt_mark_block_dirty - mark a block on the meta data file dirty.
 338 * @inode: inode of the meta data file
 339 * @block: block offset
 340 *
 341 * Return Value: On success, it returns 0. On error, the following negative
 342 * error code is returned.
 343 *
 344 * %-ENOMEM - Insufficient memory available.
 345 *
 346 * %-EIO - I/O error
 347 *
 348 * %-ENOENT - the specified block does not exist (hole block)
 349 */
 350int nilfs_mdt_mark_block_dirty(struct inode *inode, unsigned long block)
 351{
 352        struct buffer_head *bh;
 353        int err;
 354
 355        err = nilfs_mdt_read_block(inode, block, 0, &bh);
 356        if (unlikely(err))
 357                return err;
 358        mark_buffer_dirty(bh);
 359        nilfs_mdt_mark_dirty(inode);
 360        brelse(bh);
 361        return 0;
 362}
 363
 364int nilfs_mdt_fetch_dirty(struct inode *inode)
 365{
 366        struct nilfs_inode_info *ii = NILFS_I(inode);
 367
 368        if (nilfs_bmap_test_and_clear_dirty(ii->i_bmap)) {
 369                set_bit(NILFS_I_DIRTY, &ii->i_state);
 370                return 1;
 371        }
 372        return test_bit(NILFS_I_DIRTY, &ii->i_state);
 373}
 374
 375static int
 376nilfs_mdt_write_page(struct page *page, struct writeback_control *wbc)
 377{
 378        struct inode *inode = page->mapping->host;
 379        struct super_block *sb;
 380        int err = 0;
 381
 382        if (inode && (inode->i_sb->s_flags & MS_RDONLY)) {
 383                /*
 384                 * It means that filesystem was remounted in read-only
 385                 * mode because of error or metadata corruption. But we
 386                 * have dirty pages that try to be flushed in background.
 387                 * So, here we simply discard this dirty page.
 388                 */
 389                nilfs_clear_dirty_page(page, false);
 390                unlock_page(page);
 391                return -EROFS;
 392        }
 393
 394        redirty_page_for_writepage(wbc, page);
 395        unlock_page(page);
 396
 397        if (!inode)
 398                return 0;
 399
 400        sb = inode->i_sb;
 401
 402        if (wbc->sync_mode == WB_SYNC_ALL)
 403                err = nilfs_construct_segment(sb);
 404        else if (wbc->for_reclaim)
 405                nilfs_flush_segment(sb, inode->i_ino);
 406
 407        return err;
 408}
 409
 410
 411static const struct address_space_operations def_mdt_aops = {
 412        .writepage              = nilfs_mdt_write_page,
 413};
 414
 415static const struct inode_operations def_mdt_iops;
 416static const struct file_operations def_mdt_fops;
 417
 418
 419int nilfs_mdt_init(struct inode *inode, gfp_t gfp_mask, size_t objsz)
 420{
 421        struct nilfs_mdt_info *mi;
 422
 423        mi = kzalloc(max(sizeof(*mi), objsz), GFP_NOFS);
 424        if (!mi)
 425                return -ENOMEM;
 426
 427        init_rwsem(&mi->mi_sem);
 428        inode->i_private = mi;
 429
 430        inode->i_mode = S_IFREG;
 431        mapping_set_gfp_mask(inode->i_mapping, gfp_mask);
 432        inode->i_mapping->backing_dev_info = inode->i_sb->s_bdi;
 433
 434        inode->i_op = &def_mdt_iops;
 435        inode->i_fop = &def_mdt_fops;
 436        inode->i_mapping->a_ops = &def_mdt_aops;
 437
 438        return 0;
 439}
 440
 441void nilfs_mdt_set_entry_size(struct inode *inode, unsigned entry_size,
 442                              unsigned header_size)
 443{
 444        struct nilfs_mdt_info *mi = NILFS_MDT(inode);
 445
 446        mi->mi_entry_size = entry_size;
 447        mi->mi_entries_per_block = (1 << inode->i_blkbits) / entry_size;
 448        mi->mi_first_entry_offset = DIV_ROUND_UP(header_size, entry_size);
 449}
 450
 451/**
 452 * nilfs_mdt_setup_shadow_map - setup shadow map and bind it to metadata file
 453 * @inode: inode of the metadata file
 454 * @shadow: shadow mapping
 455 */
 456int nilfs_mdt_setup_shadow_map(struct inode *inode,
 457                               struct nilfs_shadow_map *shadow)
 458{
 459        struct nilfs_mdt_info *mi = NILFS_MDT(inode);
 460        struct backing_dev_info *bdi = inode->i_sb->s_bdi;
 461
 462        INIT_LIST_HEAD(&shadow->frozen_buffers);
 463        address_space_init_once(&shadow->frozen_data);
 464        nilfs_mapping_init(&shadow->frozen_data, inode, bdi);
 465        address_space_init_once(&shadow->frozen_btnodes);
 466        nilfs_mapping_init(&shadow->frozen_btnodes, inode, bdi);
 467        mi->mi_shadow = shadow;
 468        return 0;
 469}
 470
 471/**
 472 * nilfs_mdt_save_to_shadow_map - copy bmap and dirty pages to shadow map
 473 * @inode: inode of the metadata file
 474 */
 475int nilfs_mdt_save_to_shadow_map(struct inode *inode)
 476{
 477        struct nilfs_mdt_info *mi = NILFS_MDT(inode);
 478        struct nilfs_inode_info *ii = NILFS_I(inode);
 479        struct nilfs_shadow_map *shadow = mi->mi_shadow;
 480        int ret;
 481
 482        ret = nilfs_copy_dirty_pages(&shadow->frozen_data, inode->i_mapping);
 483        if (ret)
 484                goto out;
 485
 486        ret = nilfs_copy_dirty_pages(&shadow->frozen_btnodes,
 487                                     &ii->i_btnode_cache);
 488        if (ret)
 489                goto out;
 490
 491        nilfs_bmap_save(ii->i_bmap, &shadow->bmap_store);
 492 out:
 493        return ret;
 494}
 495
 496int nilfs_mdt_freeze_buffer(struct inode *inode, struct buffer_head *bh)
 497{
 498        struct nilfs_shadow_map *shadow = NILFS_MDT(inode)->mi_shadow;
 499        struct buffer_head *bh_frozen;
 500        struct page *page;
 501        int blkbits = inode->i_blkbits;
 502
 503        page = grab_cache_page(&shadow->frozen_data, bh->b_page->index);
 504        if (!page)
 505                return -ENOMEM;
 506
 507        if (!page_has_buffers(page))
 508                create_empty_buffers(page, 1 << blkbits, 0);
 509
 510        bh_frozen = nilfs_page_get_nth_block(page, bh_offset(bh) >> blkbits);
 511
 512        if (!buffer_uptodate(bh_frozen))
 513                nilfs_copy_buffer(bh_frozen, bh);
 514        if (list_empty(&bh_frozen->b_assoc_buffers)) {
 515                list_add_tail(&bh_frozen->b_assoc_buffers,
 516                              &shadow->frozen_buffers);
 517                set_buffer_nilfs_redirected(bh);
 518        } else {
 519                brelse(bh_frozen); /* already frozen */
 520        }
 521
 522        unlock_page(page);
 523        page_cache_release(page);
 524        return 0;
 525}
 526
 527struct buffer_head *
 528nilfs_mdt_get_frozen_buffer(struct inode *inode, struct buffer_head *bh)
 529{
 530        struct nilfs_shadow_map *shadow = NILFS_MDT(inode)->mi_shadow;
 531        struct buffer_head *bh_frozen = NULL;
 532        struct page *page;
 533        int n;
 534
 535        page = find_lock_page(&shadow->frozen_data, bh->b_page->index);
 536        if (page) {
 537                if (page_has_buffers(page)) {
 538                        n = bh_offset(bh) >> inode->i_blkbits;
 539                        bh_frozen = nilfs_page_get_nth_block(page, n);
 540                }
 541                unlock_page(page);
 542                page_cache_release(page);
 543        }
 544        return bh_frozen;
 545}
 546
 547static void nilfs_release_frozen_buffers(struct nilfs_shadow_map *shadow)
 548{
 549        struct list_head *head = &shadow->frozen_buffers;
 550        struct buffer_head *bh;
 551
 552        while (!list_empty(head)) {
 553                bh = list_first_entry(head, struct buffer_head,
 554                                      b_assoc_buffers);
 555                list_del_init(&bh->b_assoc_buffers);
 556                brelse(bh); /* drop ref-count to make it releasable */
 557        }
 558}
 559
 560/**
 561 * nilfs_mdt_restore_from_shadow_map - restore dirty pages and bmap state
 562 * @inode: inode of the metadata file
 563 */
 564void nilfs_mdt_restore_from_shadow_map(struct inode *inode)
 565{
 566        struct nilfs_mdt_info *mi = NILFS_MDT(inode);
 567        struct nilfs_inode_info *ii = NILFS_I(inode);
 568        struct nilfs_shadow_map *shadow = mi->mi_shadow;
 569
 570        down_write(&mi->mi_sem);
 571
 572        if (mi->mi_palloc_cache)
 573                nilfs_palloc_clear_cache(inode);
 574
 575        nilfs_clear_dirty_pages(inode->i_mapping, true);
 576        nilfs_copy_back_pages(inode->i_mapping, &shadow->frozen_data);
 577
 578        nilfs_clear_dirty_pages(&ii->i_btnode_cache, true);
 579        nilfs_copy_back_pages(&ii->i_btnode_cache, &shadow->frozen_btnodes);
 580
 581        nilfs_bmap_restore(ii->i_bmap, &shadow->bmap_store);
 582
 583        up_write(&mi->mi_sem);
 584}
 585
 586/**
 587 * nilfs_mdt_clear_shadow_map - truncate pages in shadow map caches
 588 * @inode: inode of the metadata file
 589 */
 590void nilfs_mdt_clear_shadow_map(struct inode *inode)
 591{
 592        struct nilfs_mdt_info *mi = NILFS_MDT(inode);
 593        struct nilfs_shadow_map *shadow = mi->mi_shadow;
 594
 595        down_write(&mi->mi_sem);
 596        nilfs_release_frozen_buffers(shadow);
 597        truncate_inode_pages(&shadow->frozen_data, 0);
 598        truncate_inode_pages(&shadow->frozen_btnodes, 0);
 599        up_write(&mi->mi_sem);
 600}
 601
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