fs/nilfs2/mdt.c

   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 "nilfs.h"
  30 #include "segment.h"
  31 #include "page.h"
  32 #include "mdt.h"
  33
  34
  35 #define NILFS_MDT_MAX_RA_BLOCKS         (16 - 1)
  36
  37 #define INIT_UNUSED_INODE_FIELDS
  38
  39 static int
  40 nilfs_mdt_insert_new_block(struct inode *inode, unsigned long block,
  41                            struct buffer_head *bh,
  42                            void (*init_block)(struct inode *,
  43                                               struct buffer_head *, void *))
  44 {
  45         struct nilfs_inode_info *ii = NILFS_I(inode);
  46         void *kaddr;
  47         int ret;
  48
  49         /* Caller exclude read accesses using page lock */
  50
  51         /* set_buffer_new(bh); */
  52         bh->b_blocknr = 0;
  53
  54         ret = nilfs_bmap_insert(ii->i_bmap, block, (unsigned long)bh);
  55         if (unlikely(ret))
  56                 return ret;
  57
  58         set_buffer_mapped(bh);
  59
  60         kaddr = kmap_atomic(bh->b_page, KM_USER0);
  61         memset(kaddr + bh_offset(bh), 0, 1 << inode->i_blkbits);
  62         if (init_block)
  63                 init_block(inode, bh, kaddr);
  64         flush_dcache_page(bh->b_page);
  65         kunmap_atomic(kaddr, KM_USER0);
  66
  67         set_buffer_uptodate(bh);
  68         nilfs_mark_buffer_dirty(bh);
  69         nilfs_mdt_mark_dirty(inode);
  70         return 0;
  71 }
  72
  73 static int nilfs_mdt_create_block(struct inode *inode, unsigned long block,
  74                                   struct buffer_head **out_bh,
  75                                   void (*init_block)(struct inode *,
  76                                                      struct buffer_head *,
  77                                                      void *))
  78 {
  79         struct the_nilfs *nilfs = NILFS_MDT(inode)->mi_nilfs;
  80         struct super_block *sb = inode->i_sb;
  81         struct nilfs_transaction_info ti;
  82         struct buffer_head *bh;
  83         int err;
  84
  85         if (!sb) {
  86                 /*
  87                  * Make sure this function is not called from any
  88                  * read-only context.
  89                  */
  90                 if (!nilfs->ns_writer) {
  91                         WARN_ON(1);
  92                         err = -EROFS;
  93                         goto out;
  94                 }
  95                 sb = nilfs->ns_writer->s_super;
  96         }
  97
  98         nilfs_transaction_begin(sb, &ti, 0);
  99
 100         err = -ENOMEM;
 101         bh = nilfs_grab_buffer(inode, inode->i_mapping, block, 0);
 102         if (unlikely(!bh))
 103                 goto failed_unlock;
 104
 105         err = -EEXIST;
 106         if (buffer_uptodate(bh))
 107                 goto failed_bh;
 108
 109         wait_on_buffer(bh);
 110         if (buffer_uptodate(bh))
 111                 goto failed_bh;
 112
 113         bh->b_bdev = nilfs->ns_bdev;
 114         err = nilfs_mdt_insert_new_block(inode, block, bh, init_block);
 115         if (likely(!err)) {
 116                 get_bh(bh);
 117                 *out_bh = bh;
 118         }
 119
 120  failed_bh:
 121         unlock_page(bh->b_page);
 122         page_cache_release(bh->b_page);
 123         brelse(bh);
 124
 125  failed_unlock:
 126         if (likely(!err))
 127                 err = nilfs_transaction_commit(sb);
 128         else
 129                 nilfs_transaction_abort(sb);
 130  out:
 131         return err;
 132 }
 133
 134 static int
 135 nilfs_mdt_submit_block(struct inode *inode, unsigned long blkoff,
 136                        int mode, struct buffer_head **out_bh)
 137 {
 138         struct buffer_head *bh;
 139         __u64 blknum = 0;
 140         int ret = -ENOMEM;
 141
 142         bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
 143         if (unlikely(!bh))
 144                 goto failed;
 145
 146         ret = -EEXIST; /* internal code */
 147         if (buffer_uptodate(bh))
 148                 goto out;
 149
 150         if (mode == READA) {
 151                 if (!trylock_buffer(bh)) {
 152                         ret = -EBUSY;
 153                         goto failed_bh;
 154                 }
 155         } else /* mode == READ */
 156                 lock_buffer(bh);
 157
 158         if (buffer_uptodate(bh)) {
 159                 unlock_buffer(bh);
 160                 goto out;
 161         }
 162
 163         ret = nilfs_bmap_lookup(NILFS_I(inode)->i_bmap, blkoff, &blknum);
 164         if (unlikely(ret)) {
 165                 unlock_buffer(bh);
 166                 goto failed_bh;
 167         }
 168         bh->b_bdev = NILFS_MDT(inode)->mi_nilfs->ns_bdev;
 169         bh->b_blocknr = (sector_t)blknum;
 170         set_buffer_mapped(bh);
 171
 172         bh->b_end_io = end_buffer_read_sync;
 173         get_bh(bh);
 174         submit_bh(mode, bh);
 175         ret = 0;
 176  out:
 177         get_bh(bh);
 178         *out_bh = bh;
 179
 180  failed_bh:
 181         unlock_page(bh->b_page);
 182         page_cache_release(bh->b_page);
 183         brelse(bh);
 184  failed:
 185         return ret;
 186 }
 187
 188 static int nilfs_mdt_read_block(struct inode *inode, unsigned long block,
 189                                 struct buffer_head **out_bh)
 190 {
 191         struct buffer_head *first_bh, *bh;
 192         unsigned long blkoff;
 193         int i, nr_ra_blocks = NILFS_MDT_MAX_RA_BLOCKS;
 194         int err;
 195
 196         err = nilfs_mdt_submit_block(inode, block, READ, &first_bh);
 197         if (err == -EEXIST) /* internal code */
 198                 goto out;
 199
 200         if (unlikely(err))
 201                 goto failed;
 202
 203         blkoff = block + 1;
 204         for (i = 0; i < nr_ra_blocks; i++, blkoff++) {
 205                 err = nilfs_mdt_submit_block(inode, blkoff, READA, &bh);
 206                 if (likely(!err || err == -EEXIST))
 207                         brelse(bh);
 208                 else if (err != -EBUSY)
 209                         break; /* abort readahead if bmap lookup failed */
 210
 211                 if (!buffer_locked(first_bh))
 212                         goto out_no_wait;
 213         }
 214
 215         wait_on_buffer(first_bh);
 216
 217  out_no_wait:
 218         err = -EIO;
 219         if (!buffer_uptodate(first_bh))
 220                 goto failed_bh;
 221  out:
 222         *out_bh = first_bh;
 223         return 0;
 224
 225  failed_bh:
 226         brelse(first_bh);
 227  failed:
 228         return err;
 229 }
 230
 231 /**
 232  * nilfs_mdt_get_block - read or create a buffer on meta data file.
 233  * @inode: inode of the meta data file
 234  * @blkoff: block offset
 235  * @create: create flag
 236  * @init_block: initializer used for newly allocated block
 237  * @out_bh: output of a pointer to the buffer_head
 238  *
 239  * nilfs_mdt_get_block() looks up the specified buffer and tries to create
 240  * a new buffer if @create is not zero.  On success, the returned buffer is
 241  * assured to be either existing or formatted using a buffer lock on success.
 242  * @out_bh is substituted only when zero is returned.
 243  *
 244  * Return Value: On success, it returns 0. On error, the following negative
 245  * error code is returned.
 246  *
 247  * %-ENOMEM - Insufficient memory available.
 248  *
 249  * %-EIO - I/O error
 250  *
 251  * %-ENOENT - the specified block does not exist (hole block)
 252  *
 253  * %-EINVAL - bmap is broken. (the caller should call nilfs_error())
 254  *
 255  * %-EROFS - Read only filesystem (for create mode)
 256  */
 257 int nilfs_mdt_get_block(struct inode *inode, unsigned long blkoff, int create,
 258                         void (*init_block)(struct inode *,
 259                                            struct buffer_head *, void *),
 260                         struct buffer_head **out_bh)
 261 {
 262         int ret;
 263
 264         /* Should be rewritten with merging nilfs_mdt_read_block() */
 265  retry:
 266         ret = nilfs_mdt_read_block(inode, blkoff, out_bh);
 267         if (!create || ret != -ENOENT)
 268                 return ret;
 269
 270         ret = nilfs_mdt_create_block(inode, blkoff, out_bh, init_block);
 271         if (unlikely(ret == -EEXIST)) {
 272                 /* create = 0; */  /* limit read-create loop retries */
 273                 goto retry;
 274         }
 275         return ret;
 276 }
 277
 278 /**
 279  * nilfs_mdt_delete_block - make a hole on the meta data file.
 280  * @inode: inode of the meta data file
 281  * @block: block offset
 282  *
 283  * Return Value: On success, zero is returned.
 284  * On error, one of the following negative error code is returned.
 285  *
 286  * %-ENOMEM - Insufficient memory available.
 287  *
 288  * %-EIO - I/O error
 289  *
 290  * %-EINVAL - bmap is broken. (the caller should call nilfs_error())
 291  */
 292 int nilfs_mdt_delete_block(struct inode *inode, unsigned long block)
 293 {
 294         struct nilfs_inode_info *ii = NILFS_I(inode);
 295         int err;
 296
 297         err = nilfs_bmap_delete(ii->i_bmap, block);
 298         if (!err || err == -ENOENT) {
 299                 nilfs_mdt_mark_dirty(inode);
 300                 nilfs_mdt_forget_block(inode, block);
 301         }
 302         return err;
 303 }
 304
 305 /**
 306  * nilfs_mdt_forget_block - discard dirty state and try to remove the page
 307  * @inode: inode of the meta data file
 308  * @block: block offset
 309  *
 310  * nilfs_mdt_forget_block() clears a dirty flag of the specified buffer, and
 311  * tries to release the page including the buffer from a page cache.
 312  *
 313  * Return Value: On success, 0 is returned. On error, one of the following
 314  * negative error code is returned.
 315  *
 316  * %-EBUSY - page has an active buffer.
 317  *
 318  * %-ENOENT - page cache has no page addressed by the offset.
 319  */
 320 int nilfs_mdt_forget_block(struct inode *inode, unsigned long block)
 321 {
 322         pgoff_t index = (pgoff_t)block >>
 323                 (PAGE_CACHE_SHIFT - inode->i_blkbits);
 324         struct page *page;
 325         unsigned long first_block;
 326         int ret = 0;
 327         int still_dirty;
 328
 329         page = find_lock_page(inode->i_mapping, index);
 330         if (!page)
 331                 return -ENOENT;
 332
 333         wait_on_page_writeback(page);
 334
 335         first_block = (unsigned long)index <<
 336                 (PAGE_CACHE_SHIFT - inode->i_blkbits);
 337         if (page_has_buffers(page)) {
 338                 struct buffer_head *bh;
 339
 340                 bh = nilfs_page_get_nth_block(page, block - first_block);
 341                 nilfs_forget_buffer(bh);
 342         }
 343         still_dirty = PageDirty(page);
 344         unlock_page(page);
 345         page_cache_release(page);
 346
 347         if (still_dirty ||
 348             invalidate_inode_pages2_range(inode->i_mapping, index, index) != 0)
 349                 ret = -EBUSY;
 350         return ret;
 351 }
 352
 353 /**
 354  * nilfs_mdt_mark_block_dirty - mark a block on the meta data file dirty.
 355  * @inode: inode of the meta data file
 356  * @block: block offset
 357  *
 358  * Return Value: On success, it returns 0. On error, the following negative
 359  * error code is returned.
 360  *
 361  * %-ENOMEM - Insufficient memory available.
 362  *
 363  * %-EIO - I/O error
 364  *
 365  * %-ENOENT - the specified block does not exist (hole block)
 366  *
 367  * %-EINVAL - bmap is broken. (the caller should call nilfs_error())
 368  */
 369 int nilfs_mdt_mark_block_dirty(struct inode *inode, unsigned long block)
 370 {
 371         struct buffer_head *bh;
 372         int err;
 373
 374         err = nilfs_mdt_read_block(inode, block, &bh);
 375         if (unlikely(err))
 376                 return err;
 377         nilfs_mark_buffer_dirty(bh);
 378         nilfs_mdt_mark_dirty(inode);
 379         brelse(bh);
 380         return 0;
 381 }
 382
 383 int nilfs_mdt_fetch_dirty(struct inode *inode)
 384 {
 385         struct nilfs_inode_info *ii = NILFS_I(inode);
 386
 387         if (nilfs_bmap_test_and_clear_dirty(ii->i_bmap)) {
 388                 set_bit(NILFS_I_DIRTY, &ii->i_state);
 389                 return 1;
 390         }
 391         return test_bit(NILFS_I_DIRTY, &ii->i_state);
 392 }
 393
 394 static int
 395 nilfs_mdt_write_page(struct page *page, struct writeback_control *wbc)
 396 {
 397         struct inode *inode = container_of(page->mapping,
 398                                            struct inode, i_data);
 399         struct super_block *sb = inode->i_sb;
 400         struct the_nilfs *nilfs = NILFS_MDT(inode)->mi_nilfs;
 401         struct nilfs_sb_info *writer = NULL;
 402         int err = 0;
 403
 404         redirty_page_for_writepage(wbc, page);
 405         unlock_page(page);
 406
 407         if (page->mapping->assoc_mapping)
 408                 return 0; /* Do not request flush for shadow page cache */
 409         if (!sb) {
 410                 down_read(&nilfs->ns_writer_sem);
 411                 writer = nilfs->ns_writer;
 412                 if (!writer) {
 413                         up_read(&nilfs->ns_writer_sem);
 414                         return -EROFS;
 415                 }
 416                 sb = writer->s_super;
 417         }
 418
 419         if (wbc->sync_mode == WB_SYNC_ALL)
 420                 err = nilfs_construct_segment(sb);
 421         else if (wbc->for_reclaim)
 422                 nilfs_flush_segment(sb, inode->i_ino);
 423
 424         if (writer)
 425                 up_read(&nilfs->ns_writer_sem);
 426         return err;
 427 }
 428
 429
 430 static const struct address_space_operations def_mdt_aops = {
 431         .writepage              = nilfs_mdt_write_page,
 432         .sync_page              = block_sync_page,
 433 };
 434
 435 static const struct inode_operations def_mdt_iops;
 436 static const struct file_operations def_mdt_fops;
 437
 438 /*
 439  * NILFS2 uses pseudo inodes for meta data files such as DAT, cpfile, sufile,
 440  * ifile, or gcinodes.  This allows the B-tree code and segment constructor
 441  * to treat them like regular files, and this helps to simplify the
 442  * implementation.
 443  *   On the other hand, some of the pseudo inodes have an irregular point:
 444  * They don't have valid inode->i_sb pointer because their lifetimes are
 445  * longer than those of the super block structs; they may continue for
 446  * several consecutive mounts/umounts.  This would need discussions.
 447  */
 448 struct inode *
 449 nilfs_mdt_new_common(struct the_nilfs *nilfs, struct super_block *sb,
 450                      ino_t ino, gfp_t gfp_mask)
 451 {
 452         struct inode *inode = nilfs_alloc_inode_common(nilfs);
 453
 454         if (!inode)
 455                 return NULL;
 456         else {
 457                 struct address_space * const mapping = &inode->i_data;
 458                 struct nilfs_mdt_info *mi = kzalloc(sizeof(*mi), GFP_NOFS);
 459
 460                 if (!mi) {
 461                         nilfs_destroy_inode(inode);
 462                         return NULL;
 463                 }
 464                 mi->mi_nilfs = nilfs;
 465                 init_rwsem(&mi->mi_sem);
 466
 467                 inode->i_sb = sb; /* sb may be NULL for some meta data files */
 468                 inode->i_blkbits = nilfs->ns_blocksize_bits;
 469                 inode->i_flags = 0;
 470                 atomic_set(&inode->i_count, 1);
 471                 inode->i_nlink = 1;
 472                 inode->i_ino = ino;
 473                 inode->i_mode = S_IFREG;
 474                 inode->i_private = mi;
 475
 476 #ifdef INIT_UNUSED_INODE_FIELDS
 477                 atomic_set(&inode->i_writecount, 0);
 478                 inode->i_size = 0;
 479                 inode->i_blocks = 0;
 480                 inode->i_bytes = 0;
 481                 inode->i_generation = 0;
 482 #ifdef CONFIG_QUOTA
 483                 memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
 484 #endif
 485                 inode->i_pipe = NULL;
 486                 inode->i_bdev = NULL;
 487                 inode->i_cdev = NULL;
 488                 inode->i_rdev = 0;
 489 #ifdef CONFIG_SECURITY
 490                 inode->i_security = NULL;
 491 #endif
 492                 inode->dirtied_when = 0;
 493
 494                 INIT_LIST_HEAD(&inode->i_list);
 495                 INIT_LIST_HEAD(&inode->i_sb_list);
 496                 inode->i_state = 0;
 497 #endif
 498
 499                 spin_lock_init(&inode->i_lock);
 500                 mutex_init(&inode->i_mutex);
 501                 init_rwsem(&inode->i_alloc_sem);
 502
 503                 mapping->host = NULL;  /* instead of inode */
 504                 mapping->flags = 0;
 505                 mapping_set_gfp_mask(mapping, gfp_mask);
 506                 mapping->assoc_mapping = NULL;
 507                 mapping->backing_dev_info = nilfs->ns_bdi;
 508
 509                 inode->i_mapping = mapping;
 510         }
 511
 512         return inode;
 513 }
 514
 515 struct inode *nilfs_mdt_new(struct the_nilfs *nilfs, struct super_block *sb,
 516                             ino_t ino)
 517 {
 518         struct inode *inode = nilfs_mdt_new_common(nilfs, sb, ino,
 519                                                    NILFS_MDT_GFP);
 520
 521         if (!inode)
 522                 return NULL;
 523
 524         inode->i_op = &def_mdt_iops;
 525         inode->i_fop = &def_mdt_fops;
 526         inode->i_mapping->a_ops = &def_mdt_aops;
 527         return inode;
 528 }
 529
 530 void nilfs_mdt_set_entry_size(struct inode *inode, unsigned entry_size,
 531                               unsigned header_size)
 532 {
 533         struct nilfs_mdt_info *mi = NILFS_MDT(inode);
 534
 535         mi->mi_entry_size = entry_size;
 536         mi->mi_entries_per_block = (1 << inode->i_blkbits) / entry_size;
 537         mi->mi_first_entry_offset = DIV_ROUND_UP(header_size, entry_size);
 538 }
 539
 540 void nilfs_mdt_set_shadow(struct inode *orig, struct inode *shadow)
 541 {
 542         shadow->i_mapping->assoc_mapping = orig->i_mapping;
 543         NILFS_I(shadow)->i_btnode_cache.assoc_mapping =
 544                 &NILFS_I(orig)->i_btnode_cache;
 545 }
 546
 547 void nilfs_mdt_clear(struct inode *inode)
 548 {
 549         struct nilfs_inode_info *ii = NILFS_I(inode);
 550
 551         invalidate_mapping_pages(inode->i_mapping, 0, -1);
 552         truncate_inode_pages(inode->i_mapping, 0);
 553
 554         nilfs_bmap_clear(ii->i_bmap);
 555         nilfs_btnode_cache_clear(&ii->i_btnode_cache);
 556 }
 557
 558 void nilfs_mdt_destroy(struct inode *inode)
 559 {
 560         struct nilfs_mdt_info *mdi = NILFS_MDT(inode);
 561
 562         kfree(mdi->mi_bgl); /* kfree(NULL) is safe */
 563         kfree(mdi);
 564         nilfs_destroy_inode(inode);
 565 }