git.oblomov.eu Git - linux-2.6/blob - fs/nilfs2/segment.c

   1 /*
   2  * segment.c - NILFS segment constructor.
   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
  24 #include <linux/pagemap.h>
  25 #include <linux/buffer_head.h>
  26 #include <linux/writeback.h>
  27 #include <linux/bio.h>
  28 #include <linux/completion.h>
  29 #include <linux/blkdev.h>
  30 #include <linux/backing-dev.h>
  31 #include <linux/freezer.h>
  32 #include <linux/kthread.h>
  33 #include <linux/crc32.h>
  34 #include <linux/pagevec.h>
  35 #include "nilfs.h"
  36 #include "btnode.h"
  37 #include "page.h"
  38 #include "segment.h"
  39 #include "sufile.h"
  40 #include "cpfile.h"
  41 #include "ifile.h"
  42 #include "seglist.h"
  43 #include "segbuf.h"
  44
  45
  46 /*
  47  * Segment constructor
  48  */
  49 #define SC_N_INODEVEC   16   /* Size of locally allocated inode vector */
  50
  51 #define SC_MAX_SEGDELTA 64   /* Upper limit of the number of segments
  52                                 appended in collection retry loop */
  53
  54 /* Construction mode */
  55 enum {
  56         SC_LSEG_SR = 1, /* Make a logical segment having a super root */
  57         SC_LSEG_DSYNC,  /* Flush data blocks of a given file and make
  58                            a logical segment without a super root */
  59         SC_FLUSH_FILE,  /* Flush data files, leads to segment writes without
  60                            creating a checkpoint */
  61         SC_FLUSH_DAT,   /* Flush DAT file. This also creates segments without
  62                            a checkpoint */
  63 };
  64
  65 /* Stage numbers of dirty block collection */
  66 enum {
  67         NILFS_ST_INIT = 0,
  68         NILFS_ST_GC,            /* Collecting dirty blocks for GC */
  69         NILFS_ST_FILE,
  70         NILFS_ST_IFILE,
  71         NILFS_ST_CPFILE,
  72         NILFS_ST_SUFILE,
  73         NILFS_ST_DAT,
  74         NILFS_ST_SR,            /* Super root */
  75         NILFS_ST_DSYNC,         /* Data sync blocks */
  76         NILFS_ST_DONE,
  77 };
  78
  79 /* State flags of collection */
  80 #define NILFS_CF_NODE           0x0001  /* Collecting node blocks */
  81 #define NILFS_CF_IFILE_STARTED  0x0002  /* IFILE stage has started */
  82 #define NILFS_CF_HISTORY_MASK   (NILFS_CF_IFILE_STARTED)
  83
  84 /* Operations depending on the construction mode and file type */
  85 struct nilfs_sc_operations {
  86         int (*collect_data)(struct nilfs_sc_info *, struct buffer_head *,
  87                             struct inode *);
  88         int (*collect_node)(struct nilfs_sc_info *, struct buffer_head *,
  89                             struct inode *);
  90         int (*collect_bmap)(struct nilfs_sc_info *, struct buffer_head *,
  91                             struct inode *);
  92         void (*write_data_binfo)(struct nilfs_sc_info *,
  93                                  struct nilfs_segsum_pointer *,
  94                                  union nilfs_binfo *);
  95         void (*write_node_binfo)(struct nilfs_sc_info *,
  96                                  struct nilfs_segsum_pointer *,
  97                                  union nilfs_binfo *);
  98 };
  99
 100 /*
 101  * Other definitions
 102  */
 103 static void nilfs_segctor_start_timer(struct nilfs_sc_info *);
 104 static void nilfs_segctor_do_flush(struct nilfs_sc_info *, int);
 105 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *);
 106 static void nilfs_dispose_list(struct nilfs_sb_info *, struct list_head *,
 107                                int);
 108
 109 #define nilfs_cnt32_gt(a, b)   \
 110         (typecheck(__u32, a) && typecheck(__u32, b) && \
 111          ((__s32)(b) - (__s32)(a) < 0))
 112 #define nilfs_cnt32_ge(a, b)   \
 113         (typecheck(__u32, a) && typecheck(__u32, b) && \
 114          ((__s32)(a) - (__s32)(b) >= 0))
 115 #define nilfs_cnt32_lt(a, b)  nilfs_cnt32_gt(b, a)
 116 #define nilfs_cnt32_le(a, b)  nilfs_cnt32_ge(b, a)
 117
 118 /*
 119  * Transaction
 120  */
 121 static struct kmem_cache *nilfs_transaction_cachep;
 122
 123 /**
 124  * nilfs_init_transaction_cache - create a cache for nilfs_transaction_info
 125  *
 126  * nilfs_init_transaction_cache() creates a slab cache for the struct
 127  * nilfs_transaction_info.
 128  *
 129  * Return Value: On success, it returns 0. On error, one of the following
 130  * negative error code is returned.
 131  *
 132  * %-ENOMEM - Insufficient memory available.
 133  */
 134 int nilfs_init_transaction_cache(void)
 135 {
 136         nilfs_transaction_cachep =
 137                 kmem_cache_create("nilfs2_transaction_cache",
 138                                   sizeof(struct nilfs_transaction_info),
 139                                   0, SLAB_RECLAIM_ACCOUNT, NULL);
 140         return (nilfs_transaction_cachep == NULL) ? -ENOMEM : 0;
 141 }
 142
 143 /**
 144  * nilfs_detroy_transaction_cache - destroy the cache for transaction info
 145  *
 146  * nilfs_destroy_transaction_cache() frees the slab cache for the struct
 147  * nilfs_transaction_info.
 148  */
 149 void nilfs_destroy_transaction_cache(void)
 150 {
 151         kmem_cache_destroy(nilfs_transaction_cachep);
 152 }
 153
 154 static int nilfs_prepare_segment_lock(struct nilfs_transaction_info *ti)
 155 {
 156         struct nilfs_transaction_info *cur_ti = current->journal_info;
 157         void *save = NULL;
 158
 159         if (cur_ti) {
 160                 if (cur_ti->ti_magic == NILFS_TI_MAGIC)
 161                         return ++cur_ti->ti_count;
 162                 else {
 163                         /*
 164                          * If journal_info field is occupied by other FS,
 165                          * it is saved and will be restored on
 166                          * nilfs_transaction_commit().
 167                          */
 168                         printk(KERN_WARNING
 169                                "NILFS warning: journal info from a different "
 170                                "FS\n");
 171                         save = current->journal_info;
 172                 }
 173         }
 174         if (!ti) {
 175                 ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
 176                 if (!ti)
 177                         return -ENOMEM;
 178                 ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
 179         } else {
 180                 ti->ti_flags = 0;
 181         }
 182         ti->ti_count = 0;
 183         ti->ti_save = save;
 184         ti->ti_magic = NILFS_TI_MAGIC;
 185         current->journal_info = ti;
 186         return 0;
 187 }
 188
 189 /**
 190  * nilfs_transaction_begin - start indivisible file operations.
 191  * @sb: super block
 192  * @ti: nilfs_transaction_info
 193  * @vacancy_check: flags for vacancy rate checks
 194  *
 195  * nilfs_transaction_begin() acquires a reader/writer semaphore, called
 196  * the segment semaphore, to make a segment construction and write tasks
 197  * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
 198  * The region enclosed by these two functions can be nested.  To avoid a
 199  * deadlock, the semaphore is only acquired or released in the outermost call.
 200  *
 201  * This function allocates a nilfs_transaction_info struct to keep context
 202  * information on it.  It is initialized and hooked onto the current task in
 203  * the outermost call.  If a pre-allocated struct is given to @ti, it is used
 204  * instead; othewise a new struct is assigned from a slab.
 205  *
 206  * When @vacancy_check flag is set, this function will check the amount of
 207  * free space, and will wait for the GC to reclaim disk space if low capacity.
 208  *
 209  * Return Value: On success, 0 is returned. On error, one of the following
 210  * negative error code is returned.
 211  *
 212  * %-ENOMEM - Insufficient memory available.
 213  *
 214  * %-ENOSPC - No space left on device
 215  */
 216 int nilfs_transaction_begin(struct super_block *sb,
 217                             struct nilfs_transaction_info *ti,
 218                             int vacancy_check)
 219 {
 220         struct nilfs_sb_info *sbi;
 221         struct the_nilfs *nilfs;
 222         int ret = nilfs_prepare_segment_lock(ti);
 223
 224         if (unlikely(ret < 0))
 225                 return ret;
 226         if (ret > 0)
 227                 return 0;
 228
 229         sbi = NILFS_SB(sb);
 230         nilfs = sbi->s_nilfs;
 231         down_read(&nilfs->ns_segctor_sem);
 232         if (vacancy_check && nilfs_near_disk_full(nilfs)) {
 233                 up_read(&nilfs->ns_segctor_sem);
 234                 ret = -ENOSPC;
 235                 goto failed;
 236         }
 237         return 0;
 238
 239  failed:
 240         ti = current->journal_info;
 241         current->journal_info = ti->ti_save;
 242         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
 243                 kmem_cache_free(nilfs_transaction_cachep, ti);
 244         return ret;
 245 }
 246
 247 /**
 248  * nilfs_transaction_commit - commit indivisible file operations.
 249  * @sb: super block
 250  *
 251  * nilfs_transaction_commit() releases the read semaphore which is
 252  * acquired by nilfs_transaction_begin(). This is only performed
 253  * in outermost call of this function.  If a commit flag is set,
 254  * nilfs_transaction_commit() sets a timer to start the segment
 255  * constructor.  If a sync flag is set, it starts construction
 256  * directly.
 257  */
 258 int nilfs_transaction_commit(struct super_block *sb)
 259 {
 260         struct nilfs_transaction_info *ti = current->journal_info;
 261         struct nilfs_sb_info *sbi;
 262         struct nilfs_sc_info *sci;
 263         int err = 0;
 264
 265         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
 266         ti->ti_flags |= NILFS_TI_COMMIT;
 267         if (ti->ti_count > 0) {
 268                 ti->ti_count--;
 269                 return 0;
 270         }
 271         sbi = NILFS_SB(sb);
 272         sci = NILFS_SC(sbi);
 273         if (sci != NULL) {
 274                 if (ti->ti_flags & NILFS_TI_COMMIT)
 275                         nilfs_segctor_start_timer(sci);
 276                 if (atomic_read(&sbi->s_nilfs->ns_ndirtyblks) >
 277                     sci->sc_watermark)
 278                         nilfs_segctor_do_flush(sci, 0);
 279         }
 280         up_read(&sbi->s_nilfs->ns_segctor_sem);
 281         current->journal_info = ti->ti_save;
 282
 283         if (ti->ti_flags & NILFS_TI_SYNC)
 284                 err = nilfs_construct_segment(sb);
 285         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
 286                 kmem_cache_free(nilfs_transaction_cachep, ti);
 287         return err;
 288 }
 289
 290 void nilfs_transaction_abort(struct super_block *sb)
 291 {
 292         struct nilfs_transaction_info *ti = current->journal_info;
 293
 294         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
 295         if (ti->ti_count > 0) {
 296                 ti->ti_count--;
 297                 return;
 298         }
 299         up_read(&NILFS_SB(sb)->s_nilfs->ns_segctor_sem);
 300
 301         current->journal_info = ti->ti_save;
 302         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
 303                 kmem_cache_free(nilfs_transaction_cachep, ti);
 304 }
 305
 306 void nilfs_relax_pressure_in_lock(struct super_block *sb)
 307 {
 308         struct nilfs_sb_info *sbi = NILFS_SB(sb);
 309         struct nilfs_sc_info *sci = NILFS_SC(sbi);
 310         struct the_nilfs *nilfs = sbi->s_nilfs;
 311
 312         if (!sci || !sci->sc_flush_request)
 313                 return;
 314
 315         set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
 316         up_read(&nilfs->ns_segctor_sem);
 317
 318         down_write(&nilfs->ns_segctor_sem);
 319         if (sci->sc_flush_request &&
 320             test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
 321                 struct nilfs_transaction_info *ti = current->journal_info;
 322
 323                 ti->ti_flags |= NILFS_TI_WRITER;
 324                 nilfs_segctor_do_immediate_flush(sci);
 325                 ti->ti_flags &= ~NILFS_TI_WRITER;
 326         }
 327         downgrade_write(&nilfs->ns_segctor_sem);
 328 }
 329
 330 static void nilfs_transaction_lock(struct nilfs_sb_info *sbi,
 331                                    struct nilfs_transaction_info *ti,
 332                                    int gcflag)
 333 {
 334         struct nilfs_transaction_info *cur_ti = current->journal_info;
 335
 336         WARN_ON(cur_ti);
 337         ti->ti_flags = NILFS_TI_WRITER;
 338         ti->ti_count = 0;
 339         ti->ti_save = cur_ti;
 340         ti->ti_magic = NILFS_TI_MAGIC;
 341         INIT_LIST_HEAD(&ti->ti_garbage);
 342         current->journal_info = ti;
 343
 344         for (;;) {
 345                 down_write(&sbi->s_nilfs->ns_segctor_sem);
 346                 if (!test_bit(NILFS_SC_PRIOR_FLUSH, &NILFS_SC(sbi)->sc_flags))
 347                         break;
 348
 349                 nilfs_segctor_do_immediate_flush(NILFS_SC(sbi));
 350
 351                 up_write(&sbi->s_nilfs->ns_segctor_sem);
 352                 yield();
 353         }
 354         if (gcflag)
 355                 ti->ti_flags |= NILFS_TI_GC;
 356 }
 357
 358 static void nilfs_transaction_unlock(struct nilfs_sb_info *sbi)
 359 {
 360         struct nilfs_transaction_info *ti = current->journal_info;
 361
 362         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
 363         BUG_ON(ti->ti_count > 0);
 364
 365         up_write(&sbi->s_nilfs->ns_segctor_sem);
 366         current->journal_info = ti->ti_save;
 367         if (!list_empty(&ti->ti_garbage))
 368                 nilfs_dispose_list(sbi, &ti->ti_garbage, 0);
 369 }
 370
 371 static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
 372                                             struct nilfs_segsum_pointer *ssp,
 373                                             unsigned bytes)
 374 {
 375         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
 376         unsigned blocksize = sci->sc_super->s_blocksize;
 377         void *p;
 378
 379         if (unlikely(ssp->offset + bytes > blocksize)) {
 380                 ssp->offset = 0;
 381                 BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
 382                                                &segbuf->sb_segsum_buffers));
 383                 ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
 384         }
 385         p = ssp->bh->b_data + ssp->offset;
 386         ssp->offset += bytes;
 387         return p;
 388 }
 389
 390 /**
 391  * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
 392  * @sci: nilfs_sc_info
 393  */
 394 static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
 395 {
 396         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
 397         struct buffer_head *sumbh;
 398         unsigned sumbytes;
 399         unsigned flags = 0;
 400         int err;
 401
 402         if (nilfs_doing_gc())
 403                 flags = NILFS_SS_GC;
 404         err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime);
 405         if (unlikely(err))
 406                 return err;
 407
 408         sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
 409         sumbytes = segbuf->sb_sum.sumbytes;
 410         sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
 411         sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
 412         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
 413         return 0;
 414 }
 415
 416 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
 417 {
 418         sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
 419         if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
 420                 return -E2BIG; /* The current segment is filled up
 421                                   (internal code) */
 422         sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
 423         return nilfs_segctor_reset_segment_buffer(sci);
 424 }
 425
 426 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
 427 {
 428         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
 429         int err;
 430
 431         if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
 432                 err = nilfs_segctor_feed_segment(sci);
 433                 if (err)
 434                         return err;
 435                 segbuf = sci->sc_curseg;
 436         }
 437         err = nilfs_segbuf_extend_payload(segbuf, &sci->sc_super_root);
 438         if (likely(!err))
 439                 segbuf->sb_sum.flags |= NILFS_SS_SR;
 440         return err;
 441 }
 442
 443 /*
 444  * Functions for making segment summary and payloads
 445  */
 446 static int nilfs_segctor_segsum_block_required(
 447         struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
 448         unsigned binfo_size)
 449 {
 450         unsigned blocksize = sci->sc_super->s_blocksize;
 451         /* Size of finfo and binfo is enough small against blocksize */
 452
 453         return ssp->offset + binfo_size +
 454                 (!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
 455                 blocksize;
 456 }
 457
 458 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
 459                                       struct inode *inode)
 460 {
 461         sci->sc_curseg->sb_sum.nfinfo++;
 462         sci->sc_binfo_ptr = sci->sc_finfo_ptr;
 463         nilfs_segctor_map_segsum_entry(
 464                 sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
 465
 466         if (inode->i_sb && !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
 467                 set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
 468         /* skip finfo */
 469 }
 470
 471 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
 472                                     struct inode *inode)
 473 {
 474         struct nilfs_finfo *finfo;
 475         struct nilfs_inode_info *ii;
 476         struct nilfs_segment_buffer *segbuf;
 477
 478         if (sci->sc_blk_cnt == 0)
 479                 return;
 480
 481         ii = NILFS_I(inode);
 482         finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
 483                                                  sizeof(*finfo));
 484         finfo->fi_ino = cpu_to_le64(inode->i_ino);
 485         finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
 486         finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
 487         finfo->fi_cno = cpu_to_le64(ii->i_cno);
 488
 489         segbuf = sci->sc_curseg;
 490         segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
 491                 sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
 492         sci->sc_finfo_ptr = sci->sc_binfo_ptr;
 493         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
 494 }
 495
 496 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
 497                                         struct buffer_head *bh,
 498                                         struct inode *inode,
 499                                         unsigned binfo_size)
 500 {
 501         struct nilfs_segment_buffer *segbuf;
 502         int required, err = 0;
 503
 504  retry:
 505         segbuf = sci->sc_curseg;
 506         required = nilfs_segctor_segsum_block_required(
 507                 sci, &sci->sc_binfo_ptr, binfo_size);
 508         if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
 509                 nilfs_segctor_end_finfo(sci, inode);
 510                 err = nilfs_segctor_feed_segment(sci);
 511                 if (err)
 512                         return err;
 513                 goto retry;
 514         }
 515         if (unlikely(required)) {
 516                 err = nilfs_segbuf_extend_segsum(segbuf);
 517                 if (unlikely(err))
 518                         goto failed;
 519         }
 520         if (sci->sc_blk_cnt == 0)
 521                 nilfs_segctor_begin_finfo(sci, inode);
 522
 523         nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
 524         /* Substitution to vblocknr is delayed until update_blocknr() */
 525         nilfs_segbuf_add_file_buffer(segbuf, bh);
 526         sci->sc_blk_cnt++;
 527  failed:
 528         return err;
 529 }
 530
 531 static int nilfs_handle_bmap_error(int err, const char *fname,
 532                                    struct inode *inode, struct super_block *sb)
 533 {
 534         if (err == -EINVAL) {
 535                 nilfs_error(sb, fname, "broken bmap (inode=%lu)\n",
 536                             inode->i_ino);
 537                 err = -EIO;
 538         }
 539         return err;
 540 }
 541
 542 /*
 543  * Callback functions that enumerate, mark, and collect dirty blocks
 544  */
 545 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
 546                                    struct buffer_head *bh, struct inode *inode)
 547 {
 548         int err;
 549
 550         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
 551         if (unlikely(err < 0))
 552                 return nilfs_handle_bmap_error(err, __func__, inode,
 553                                                sci->sc_super);
 554
 555         err = nilfs_segctor_add_file_block(sci, bh, inode,
 556                                            sizeof(struct nilfs_binfo_v));
 557         if (!err)
 558                 sci->sc_datablk_cnt++;
 559         return err;
 560 }
 561
 562 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
 563                                    struct buffer_head *bh,
 564                                    struct inode *inode)
 565 {
 566         int err;
 567
 568         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
 569         if (unlikely(err < 0))
 570                 return nilfs_handle_bmap_error(err, __func__, inode,
 571                                                sci->sc_super);
 572         return 0;
 573 }
 574
 575 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
 576                                    struct buffer_head *bh,
 577                                    struct inode *inode)
 578 {
 579         WARN_ON(!buffer_dirty(bh));
 580         return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
 581 }
 582
 583 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
 584                                         struct nilfs_segsum_pointer *ssp,
 585                                         union nilfs_binfo *binfo)
 586 {
 587         struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
 588                 sci, ssp, sizeof(*binfo_v));
 589         *binfo_v = binfo->bi_v;
 590 }
 591
 592 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
 593                                         struct nilfs_segsum_pointer *ssp,
 594                                         union nilfs_binfo *binfo)
 595 {
 596         __le64 *vblocknr = nilfs_segctor_map_segsum_entry(
 597                 sci, ssp, sizeof(*vblocknr));
 598         *vblocknr = binfo->bi_v.bi_vblocknr;
 599 }
 600
 601 struct nilfs_sc_operations nilfs_sc_file_ops = {
 602         .collect_data = nilfs_collect_file_data,
 603         .collect_node = nilfs_collect_file_node,
 604         .collect_bmap = nilfs_collect_file_bmap,
 605         .write_data_binfo = nilfs_write_file_data_binfo,
 606         .write_node_binfo = nilfs_write_file_node_binfo,
 607 };
 608
 609 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
 610                                   struct buffer_head *bh, struct inode *inode)
 611 {
 612         int err;
 613
 614         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
 615         if (unlikely(err < 0))
 616                 return nilfs_handle_bmap_error(err, __func__, inode,
 617                                                sci->sc_super);
 618
 619         err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
 620         if (!err)
 621                 sci->sc_datablk_cnt++;
 622         return err;
 623 }
 624
 625 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
 626                                   struct buffer_head *bh, struct inode *inode)
 627 {
 628         WARN_ON(!buffer_dirty(bh));
 629         return nilfs_segctor_add_file_block(sci, bh, inode,
 630                                             sizeof(struct nilfs_binfo_dat));
 631 }
 632
 633 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
 634                                        struct nilfs_segsum_pointer *ssp,
 635                                        union nilfs_binfo *binfo)
 636 {
 637         __le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
 638                                                           sizeof(*blkoff));
 639         *blkoff = binfo->bi_dat.bi_blkoff;
 640 }
 641
 642 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
 643                                        struct nilfs_segsum_pointer *ssp,
 644                                        union nilfs_binfo *binfo)
 645 {
 646         struct nilfs_binfo_dat *binfo_dat =
 647                 nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
 648         *binfo_dat = binfo->bi_dat;
 649 }
 650
 651 struct nilfs_sc_operations nilfs_sc_dat_ops = {
 652         .collect_data = nilfs_collect_dat_data,
 653         .collect_node = nilfs_collect_file_node,
 654         .collect_bmap = nilfs_collect_dat_bmap,
 655         .write_data_binfo = nilfs_write_dat_data_binfo,
 656         .write_node_binfo = nilfs_write_dat_node_binfo,
 657 };
 658
 659 struct nilfs_sc_operations nilfs_sc_dsync_ops = {
 660         .collect_data = nilfs_collect_file_data,
 661         .collect_node = NULL,
 662         .collect_bmap = NULL,
 663         .write_data_binfo = nilfs_write_file_data_binfo,
 664         .write_node_binfo = NULL,
 665 };
 666
 667 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
 668                                               struct list_head *listp,
 669                                               size_t nlimit,
 670                                               loff_t start, loff_t end)
 671 {
 672         struct address_space *mapping = inode->i_mapping;
 673         struct pagevec pvec;
 674         pgoff_t index = 0, last = ULONG_MAX;
 675         size_t ndirties = 0;
 676         int i;
 677
 678         if (unlikely(start != 0 || end != LLONG_MAX)) {
 679                 /*
 680                  * A valid range is given for sync-ing data pages. The
 681                  * range is rounded to per-page; extra dirty buffers
 682                  * may be included if blocksize < pagesize.
 683                  */
 684                 index = start >> PAGE_SHIFT;
 685                 last = end >> PAGE_SHIFT;
 686         }
 687         pagevec_init(&pvec, 0);
 688  repeat:
 689         if (unlikely(index > last) ||
 690             !pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
 691                                 min_t(pgoff_t, last - index,
 692                                       PAGEVEC_SIZE - 1) + 1))
 693                 return ndirties;
 694
 695         for (i = 0; i < pagevec_count(&pvec); i++) {
 696                 struct buffer_head *bh, *head;
 697                 struct page *page = pvec.pages[i];
 698
 699                 if (unlikely(page->index > last))
 700                         break;
 701
 702                 if (mapping->host) {
 703                         lock_page(page);
 704                         if (!page_has_buffers(page))
 705                                 create_empty_buffers(page,
 706                                                      1 << inode->i_blkbits, 0);
 707                         unlock_page(page);
 708                 }
 709
 710                 bh = head = page_buffers(page);
 711                 do {
 712                         if (!buffer_dirty(bh))
 713                                 continue;
 714                         get_bh(bh);
 715                         list_add_tail(&bh->b_assoc_buffers, listp);
 716                         ndirties++;
 717                         if (unlikely(ndirties >= nlimit)) {
 718                                 pagevec_release(&pvec);
 719                                 cond_resched();
 720                                 return ndirties;
 721                         }
 722                 } while (bh = bh->b_this_page, bh != head);
 723         }
 724         pagevec_release(&pvec);
 725         cond_resched();
 726         goto repeat;
 727 }
 728
 729 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
 730                                             struct list_head *listp)
 731 {
 732         struct nilfs_inode_info *ii = NILFS_I(inode);
 733         struct address_space *mapping = &ii->i_btnode_cache;
 734         struct pagevec pvec;
 735         struct buffer_head *bh, *head;
 736         unsigned int i;
 737         pgoff_t index = 0;
 738
 739         pagevec_init(&pvec, 0);
 740
 741         while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
 742                                   PAGEVEC_SIZE)) {
 743                 for (i = 0; i < pagevec_count(&pvec); i++) {
 744                         bh = head = page_buffers(pvec.pages[i]);
 745                         do {
 746                                 if (buffer_dirty(bh)) {
 747                                         get_bh(bh);
 748                                         list_add_tail(&bh->b_assoc_buffers,
 749                                                       listp);
 750                                 }
 751                                 bh = bh->b_this_page;
 752                         } while (bh != head);
 753                 }
 754                 pagevec_release(&pvec);
 755                 cond_resched();
 756         }
 757 }
 758
 759 static void nilfs_dispose_list(struct nilfs_sb_info *sbi,
 760                                struct list_head *head, int force)
 761 {
 762         struct nilfs_inode_info *ii, *n;
 763         struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
 764         unsigned nv = 0;
 765
 766         while (!list_empty(head)) {
 767                 spin_lock(&sbi->s_inode_lock);
 768                 list_for_each_entry_safe(ii, n, head, i_dirty) {
 769                         list_del_init(&ii->i_dirty);
 770                         if (force) {
 771                                 if (unlikely(ii->i_bh)) {
 772                                         brelse(ii->i_bh);
 773                                         ii->i_bh = NULL;
 774                                 }
 775                         } else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
 776                                 set_bit(NILFS_I_QUEUED, &ii->i_state);
 777                                 list_add_tail(&ii->i_dirty,
 778                                               &sbi->s_dirty_files);
 779                                 continue;
 780                         }
 781                         ivec[nv++] = ii;
 782                         if (nv == SC_N_INODEVEC)
 783                                 break;
 784                 }
 785                 spin_unlock(&sbi->s_inode_lock);
 786
 787                 for (pii = ivec; nv > 0; pii++, nv--)
 788                         iput(&(*pii)->vfs_inode);
 789         }
 790 }
 791
 792 static int nilfs_test_metadata_dirty(struct nilfs_sb_info *sbi)
 793 {
 794         struct the_nilfs *nilfs = sbi->s_nilfs;
 795         int ret = 0;
 796
 797         if (nilfs_mdt_fetch_dirty(sbi->s_ifile))
 798                 ret++;
 799         if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
 800                 ret++;
 801         if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
 802                 ret++;
 803         if (ret || nilfs_doing_gc())
 804                 if (nilfs_mdt_fetch_dirty(nilfs_dat_inode(nilfs)))
 805                         ret++;
 806         return ret;
 807 }
 808
 809 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
 810 {
 811         return list_empty(&sci->sc_dirty_files) &&
 812                 !test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
 813                 list_empty(&sci->sc_cleaning_segments) &&
 814                 (!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
 815 }
 816
 817 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
 818 {
 819         struct nilfs_sb_info *sbi = sci->sc_sbi;
 820         int ret = 0;
 821
 822         if (nilfs_test_metadata_dirty(sbi))
 823                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
 824
 825         spin_lock(&sbi->s_inode_lock);
 826         if (list_empty(&sbi->s_dirty_files) && nilfs_segctor_clean(sci))
 827                 ret++;
 828
 829         spin_unlock(&sbi->s_inode_lock);
 830         return ret;
 831 }
 832
 833 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
 834 {
 835         struct nilfs_sb_info *sbi = sci->sc_sbi;
 836         struct the_nilfs *nilfs = sbi->s_nilfs;
 837
 838         nilfs_mdt_clear_dirty(sbi->s_ifile);
 839         nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
 840         nilfs_mdt_clear_dirty(nilfs->ns_sufile);
 841         nilfs_mdt_clear_dirty(nilfs_dat_inode(nilfs));
 842 }
 843
 844 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
 845 {
 846         struct the_nilfs *nilfs = sci->sc_sbi->s_nilfs;
 847         struct buffer_head *bh_cp;
 848         struct nilfs_checkpoint *raw_cp;
 849         int err;
 850
 851         /* XXX: this interface will be changed */
 852         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
 853                                           &raw_cp, &bh_cp);
 854         if (likely(!err)) {
 855                 /* The following code is duplicated with cpfile.  But, it is
 856                    needed to collect the checkpoint even if it was not newly
 857                    created */
 858                 nilfs_mdt_mark_buffer_dirty(bh_cp);
 859                 nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
 860                 nilfs_cpfile_put_checkpoint(
 861                         nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
 862         } else
 863                 WARN_ON(err == -EINVAL || err == -ENOENT);
 864
 865         return err;
 866 }
 867
 868 static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
 869 {
 870         struct nilfs_sb_info *sbi = sci->sc_sbi;
 871         struct the_nilfs *nilfs = sbi->s_nilfs;
 872         struct buffer_head *bh_cp;
 873         struct nilfs_checkpoint *raw_cp;
 874         int err;
 875
 876         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
 877                                           &raw_cp, &bh_cp);
 878         if (unlikely(err)) {
 879                 WARN_ON(err == -EINVAL || err == -ENOENT);
 880                 goto failed_ibh;
 881         }
 882         raw_cp->cp_snapshot_list.ssl_next = 0;
 883         raw_cp->cp_snapshot_list.ssl_prev = 0;
 884         raw_cp->cp_inodes_count =
 885                 cpu_to_le64(atomic_read(&sbi->s_inodes_count));
 886         raw_cp->cp_blocks_count =
 887                 cpu_to_le64(atomic_read(&sbi->s_blocks_count));
 888         raw_cp->cp_nblk_inc =
 889                 cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
 890         raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
 891         raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
 892
 893         if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
 894                 nilfs_checkpoint_clear_minor(raw_cp);
 895         else
 896                 nilfs_checkpoint_set_minor(raw_cp);
 897
 898         nilfs_write_inode_common(sbi->s_ifile, &raw_cp->cp_ifile_inode, 1);
 899         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
 900         return 0;
 901
 902  failed_ibh:
 903         return err;
 904 }
 905
 906 static void nilfs_fill_in_file_bmap(struct inode *ifile,
 907                                     struct nilfs_inode_info *ii)
 908
 909 {
 910         struct buffer_head *ibh;
 911         struct nilfs_inode *raw_inode;
 912
 913         if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
 914                 ibh = ii->i_bh;
 915                 BUG_ON(!ibh);
 916                 raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
 917                                                   ibh);
 918                 nilfs_bmap_write(ii->i_bmap, raw_inode);
 919                 nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
 920         }
 921 }
 922
 923 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci,
 924                                             struct inode *ifile)
 925 {
 926         struct nilfs_inode_info *ii;
 927
 928         list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
 929                 nilfs_fill_in_file_bmap(ifile, ii);
 930                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
 931         }
 932 }
 933
 934 /*
 935  * CRC calculation routines
 936  */
 937 static void nilfs_fill_in_super_root_crc(struct buffer_head *bh_sr, u32 seed)
 938 {
 939         struct nilfs_super_root *raw_sr =
 940                 (struct nilfs_super_root *)bh_sr->b_data;
 941         u32 crc;
 942
 943         crc = crc32_le(seed,
 944                        (unsigned char *)raw_sr + sizeof(raw_sr->sr_sum),
 945                        NILFS_SR_BYTES - sizeof(raw_sr->sr_sum));
 946         raw_sr->sr_sum = cpu_to_le32(crc);
 947 }
 948
 949 static void nilfs_segctor_fill_in_checksums(struct nilfs_sc_info *sci,
 950                                             u32 seed)
 951 {
 952         struct nilfs_segment_buffer *segbuf;
 953
 954         if (sci->sc_super_root)
 955                 nilfs_fill_in_super_root_crc(sci->sc_super_root, seed);
 956
 957         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
 958                 nilfs_segbuf_fill_in_segsum_crc(segbuf, seed);
 959                 nilfs_segbuf_fill_in_data_crc(segbuf, seed);
 960         }
 961 }
 962
 963 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
 964                                              struct the_nilfs *nilfs)
 965 {
 966         struct buffer_head *bh_sr = sci->sc_super_root;
 967         struct nilfs_super_root *raw_sr =
 968                 (struct nilfs_super_root *)bh_sr->b_data;
 969         unsigned isz = nilfs->ns_inode_size;
 970
 971         raw_sr->sr_bytes = cpu_to_le16(NILFS_SR_BYTES);
 972         raw_sr->sr_nongc_ctime
 973                 = cpu_to_le64(nilfs_doing_gc() ?
 974                               nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
 975         raw_sr->sr_flags = 0;
 976
 977         nilfs_mdt_write_inode_direct(
 978                 nilfs_dat_inode(nilfs), bh_sr, NILFS_SR_DAT_OFFSET(isz));
 979         nilfs_mdt_write_inode_direct(
 980                 nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(isz));
 981         nilfs_mdt_write_inode_direct(
 982                 nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(isz));
 983 }
 984
 985 static void nilfs_redirty_inodes(struct list_head *head)
 986 {
 987         struct nilfs_inode_info *ii;
 988
 989         list_for_each_entry(ii, head, i_dirty) {
 990                 if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
 991                         clear_bit(NILFS_I_COLLECTED, &ii->i_state);
 992         }
 993 }
 994
 995 static void nilfs_drop_collected_inodes(struct list_head *head)
 996 {
 997         struct nilfs_inode_info *ii;
 998
 999         list_for_each_entry(ii, head, i_dirty) {
1000                 if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
1001                         continue;
1002
1003                 clear_bit(NILFS_I_INODE_DIRTY, &ii->i_state);
1004                 set_bit(NILFS_I_UPDATED, &ii->i_state);
1005         }
1006 }
1007
1008 static void nilfs_segctor_cancel_free_segments(struct nilfs_sc_info *sci,
1009                                                struct inode *sufile)
1010
1011 {
1012         struct list_head *head = &sci->sc_cleaning_segments;
1013         struct nilfs_segment_entry *ent;
1014         int err;
1015
1016         list_for_each_entry(ent, head, list) {
1017                 if (!(ent->flags & NILFS_SLH_FREED))
1018                         break;
1019                 err = nilfs_sufile_cancel_free(sufile, ent->segnum);
1020                 WARN_ON(err); /* do not happen */
1021                 ent->flags &= ~NILFS_SLH_FREED;
1022         }
1023 }
1024
1025 static int nilfs_segctor_prepare_free_segments(struct nilfs_sc_info *sci,
1026                                                struct inode *sufile)
1027 {
1028         struct list_head *head = &sci->sc_cleaning_segments;
1029         struct nilfs_segment_entry *ent;
1030         int err;
1031
1032         list_for_each_entry(ent, head, list) {
1033                 err = nilfs_sufile_free(sufile, ent->segnum);
1034                 if (unlikely(err))
1035                         return err;
1036                 ent->flags |= NILFS_SLH_FREED;
1037         }
1038         return 0;
1039 }
1040
1041 static void nilfs_segctor_commit_free_segments(struct nilfs_sc_info *sci)
1042 {
1043         nilfs_dispose_segment_list(&sci->sc_cleaning_segments);
1044 }
1045
1046 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
1047                                        struct inode *inode,
1048                                        struct list_head *listp,
1049                                        int (*collect)(struct nilfs_sc_info *,
1050                                                       struct buffer_head *,
1051                                                       struct inode *))
1052 {
1053         struct buffer_head *bh, *n;
1054         int err = 0;
1055
1056         if (collect) {
1057                 list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
1058                         list_del_init(&bh->b_assoc_buffers);
1059                         err = collect(sci, bh, inode);
1060                         brelse(bh);
1061                         if (unlikely(err))
1062                                 goto dispose_buffers;
1063                 }
1064                 return 0;
1065         }
1066
1067  dispose_buffers:
1068         while (!list_empty(listp)) {
1069                 bh = list_entry(listp->next, struct buffer_head,
1070                                 b_assoc_buffers);
1071                 list_del_init(&bh->b_assoc_buffers);
1072                 brelse(bh);
1073         }
1074         return err;
1075 }
1076
1077 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
1078 {
1079         /* Remaining number of blocks within segment buffer */
1080         return sci->sc_segbuf_nblocks -
1081                 (sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
1082 }
1083
1084 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
1085                                    struct inode *inode,
1086                                    struct nilfs_sc_operations *sc_ops)
1087 {
1088         LIST_HEAD(data_buffers);
1089         LIST_HEAD(node_buffers);
1090         int err;
1091
1092         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1093                 size_t n, rest = nilfs_segctor_buffer_rest(sci);
1094
1095                 n = nilfs_lookup_dirty_data_buffers(
1096                         inode, &data_buffers, rest + 1, 0, LLONG_MAX);
1097                 if (n > rest) {
1098                         err = nilfs_segctor_apply_buffers(
1099                                 sci, inode, &data_buffers,
1100                                 sc_ops->collect_data);
1101                         BUG_ON(!err); /* always receive -E2BIG or true error */
1102                         goto break_or_fail;
1103                 }
1104         }
1105         nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1106
1107         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1108                 err = nilfs_segctor_apply_buffers(
1109                         sci, inode, &data_buffers, sc_ops->collect_data);
1110                 if (unlikely(err)) {
1111                         /* dispose node list */
1112                         nilfs_segctor_apply_buffers(
1113                                 sci, inode, &node_buffers, NULL);
1114                         goto break_or_fail;
1115                 }
1116                 sci->sc_stage.flags |= NILFS_CF_NODE;
1117         }
1118         /* Collect node */
1119         err = nilfs_segctor_apply_buffers(
1120                 sci, inode, &node_buffers, sc_ops->collect_node);
1121         if (unlikely(err))
1122                 goto break_or_fail;
1123
1124         nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1125         err = nilfs_segctor_apply_buffers(
1126                 sci, inode, &node_buffers, sc_ops->collect_bmap);
1127         if (unlikely(err))
1128                 goto break_or_fail;
1129
1130         nilfs_segctor_end_finfo(sci, inode);
1131         sci->sc_stage.flags &= ~NILFS_CF_NODE;
1132
1133  break_or_fail:
1134         return err;
1135 }
1136
1137 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1138                                          struct inode *inode)
1139 {
1140         LIST_HEAD(data_buffers);
1141         size_t n, rest = nilfs_segctor_buffer_rest(sci);
1142         int err;
1143
1144         n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1145                                             sci->sc_dsync_start,
1146                                             sci->sc_dsync_end);
1147
1148         err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1149                                           nilfs_collect_file_data);
1150         if (!err) {
1151                 nilfs_segctor_end_finfo(sci, inode);
1152                 BUG_ON(n > rest);
1153                 /* always receive -E2BIG or true error if n > rest */
1154         }
1155         return err;
1156 }
1157
1158 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1159 {
1160         struct nilfs_sb_info *sbi = sci->sc_sbi;
1161         struct the_nilfs *nilfs = sbi->s_nilfs;
1162         struct list_head *head;
1163         struct nilfs_inode_info *ii;
1164         int err = 0;
1165
1166         switch (sci->sc_stage.scnt) {
1167         case NILFS_ST_INIT:
1168                 /* Pre-processes */
1169                 sci->sc_stage.flags = 0;
1170
1171                 if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1172                         sci->sc_nblk_inc = 0;
1173                         sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1174                         if (mode == SC_LSEG_DSYNC) {
1175                                 sci->sc_stage.scnt = NILFS_ST_DSYNC;
1176                                 goto dsync_mode;
1177                         }
1178                 }
1179
1180                 sci->sc_stage.dirty_file_ptr = NULL;
1181                 sci->sc_stage.gc_inode_ptr = NULL;
1182                 if (mode == SC_FLUSH_DAT) {
1183                         sci->sc_stage.scnt = NILFS_ST_DAT;
1184                         goto dat_stage;
1185                 }
1186                 sci->sc_stage.scnt++;  /* Fall through */
1187         case NILFS_ST_GC:
1188                 if (nilfs_doing_gc()) {
1189                         head = &sci->sc_gc_inodes;
1190                         ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1191                                                 head, i_dirty);
1192                         list_for_each_entry_continue(ii, head, i_dirty) {
1193                                 err = nilfs_segctor_scan_file(
1194                                         sci, &ii->vfs_inode,
1195                                         &nilfs_sc_file_ops);
1196                                 if (unlikely(err)) {
1197                                         sci->sc_stage.gc_inode_ptr = list_entry(
1198                                                 ii->i_dirty.prev,
1199                                                 struct nilfs_inode_info,
1200                                                 i_dirty);
1201                                         goto break_or_fail;
1202                                 }
1203                                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
1204                         }
1205                         sci->sc_stage.gc_inode_ptr = NULL;
1206                 }
1207                 sci->sc_stage.scnt++;  /* Fall through */
1208         case NILFS_ST_FILE:
1209                 head = &sci->sc_dirty_files;
1210                 ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1211                                         i_dirty);
1212                 list_for_each_entry_continue(ii, head, i_dirty) {
1213                         clear_bit(NILFS_I_DIRTY, &ii->i_state);
1214
1215                         err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1216                                                       &nilfs_sc_file_ops);
1217                         if (unlikely(err)) {
1218                                 sci->sc_stage.dirty_file_ptr =
1219                                         list_entry(ii->i_dirty.prev,
1220                                                    struct nilfs_inode_info,
1221                                                    i_dirty);
1222                                 goto break_or_fail;
1223                         }
1224                         /* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1225                         /* XXX: required ? */
1226                 }
1227                 sci->sc_stage.dirty_file_ptr = NULL;
1228                 if (mode == SC_FLUSH_FILE) {
1229                         sci->sc_stage.scnt = NILFS_ST_DONE;
1230                         return 0;
1231                 }
1232                 sci->sc_stage.scnt++;
1233                 sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1234                 /* Fall through */
1235         case NILFS_ST_IFILE:
1236                 err = nilfs_segctor_scan_file(sci, sbi->s_ifile,
1237                                               &nilfs_sc_file_ops);
1238                 if (unlikely(err))
1239                         break;
1240                 sci->sc_stage.scnt++;
1241                 /* Creating a checkpoint */
1242                 err = nilfs_segctor_create_checkpoint(sci);
1243                 if (unlikely(err))
1244                         break;
1245                 /* Fall through */
1246         case NILFS_ST_CPFILE:
1247                 err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1248                                               &nilfs_sc_file_ops);
1249                 if (unlikely(err))
1250                         break;
1251                 sci->sc_stage.scnt++;  /* Fall through */
1252         case NILFS_ST_SUFILE:
1253                 err = nilfs_segctor_prepare_free_segments(sci,
1254                                                           nilfs->ns_sufile);
1255                 if (unlikely(err))
1256                         break;
1257                 err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1258                                               &nilfs_sc_file_ops);
1259                 if (unlikely(err))
1260                         break;
1261                 sci->sc_stage.scnt++;  /* Fall through */
1262         case NILFS_ST_DAT:
1263  dat_stage:
1264                 err = nilfs_segctor_scan_file(sci, nilfs_dat_inode(nilfs),
1265                                               &nilfs_sc_dat_ops);
1266                 if (unlikely(err))
1267                         break;
1268                 if (mode == SC_FLUSH_DAT) {
1269                         sci->sc_stage.scnt = NILFS_ST_DONE;
1270                         return 0;
1271                 }
1272                 sci->sc_stage.scnt++;  /* Fall through */
1273         case NILFS_ST_SR:
1274                 if (mode == SC_LSEG_SR) {
1275                         /* Appending a super root */
1276                         err = nilfs_segctor_add_super_root(sci);
1277                         if (unlikely(err))
1278                                 break;
1279                 }
1280                 /* End of a logical segment */
1281                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1282                 sci->sc_stage.scnt = NILFS_ST_DONE;
1283                 return 0;
1284         case NILFS_ST_DSYNC:
1285  dsync_mode:
1286                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1287                 ii = sci->sc_dsync_inode;
1288                 if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1289                         break;
1290
1291                 err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1292                 if (unlikely(err))
1293                         break;
1294                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1295                 sci->sc_stage.scnt = NILFS_ST_DONE;
1296                 return 0;
1297         case NILFS_ST_DONE:
1298                 return 0;
1299         default:
1300                 BUG();
1301         }
1302
1303  break_or_fail:
1304         return err;
1305 }
1306
1307 static int nilfs_touch_segusage(struct inode *sufile, __u64 segnum)
1308 {
1309         struct buffer_head *bh_su;
1310         struct nilfs_segment_usage *raw_su;
1311         int err;
1312
1313         err = nilfs_sufile_get_segment_usage(sufile, segnum, &raw_su, &bh_su);
1314         if (unlikely(err))
1315                 return err;
1316         nilfs_mdt_mark_buffer_dirty(bh_su);
1317         nilfs_mdt_mark_dirty(sufile);
1318         nilfs_sufile_put_segment_usage(sufile, segnum, bh_su);
1319         return 0;
1320 }
1321
1322 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1323                                             struct the_nilfs *nilfs)
1324 {
1325         struct nilfs_segment_buffer *segbuf, *n;
1326         __u64 nextnum;
1327         int err;
1328
1329         if (list_empty(&sci->sc_segbufs)) {
1330                 segbuf = nilfs_segbuf_new(sci->sc_super);
1331                 if (unlikely(!segbuf))
1332                         return -ENOMEM;
1333                 list_add(&segbuf->sb_list, &sci->sc_segbufs);
1334         } else
1335                 segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1336
1337         nilfs_segbuf_map(segbuf, nilfs->ns_segnum, nilfs->ns_pseg_offset,
1338                          nilfs);
1339
1340         if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1341                 nilfs_shift_to_next_segment(nilfs);
1342                 nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1343         }
1344         sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1345
1346         err = nilfs_touch_segusage(nilfs->ns_sufile, segbuf->sb_segnum);
1347         if (unlikely(err))
1348                 return err;
1349
1350         if (nilfs->ns_segnum == nilfs->ns_nextnum) {
1351                 /* Start from the head of a new full segment */
1352                 err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1353                 if (unlikely(err))
1354                         return err;
1355         } else
1356                 nextnum = nilfs->ns_nextnum;
1357
1358         segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1359         nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1360
1361         /* truncating segment buffers */
1362         list_for_each_entry_safe_continue(segbuf, n, &sci->sc_segbufs,
1363                                           sb_list) {
1364                 list_del_init(&segbuf->sb_list);
1365                 nilfs_segbuf_free(segbuf);
1366         }
1367         return 0;
1368 }
1369
1370 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1371                                          struct the_nilfs *nilfs, int nadd)
1372 {
1373         struct nilfs_segment_buffer *segbuf, *prev, *n;
1374         struct inode *sufile = nilfs->ns_sufile;
1375         __u64 nextnextnum;
1376         LIST_HEAD(list);
1377         int err, ret, i;
1378
1379         prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1380         /*
1381          * Since the segment specified with nextnum might be allocated during
1382          * the previous construction, the buffer including its segusage may
1383          * not be dirty.  The following call ensures that the buffer is dirty
1384          * and will pin the buffer on memory until the sufile is written.
1385          */
1386         err = nilfs_touch_segusage(sufile, prev->sb_nextnum);
1387         if (unlikely(err))
1388                 return err;
1389
1390         for (i = 0; i < nadd; i++) {
1391                 /* extend segment info */
1392                 err = -ENOMEM;
1393                 segbuf = nilfs_segbuf_new(sci->sc_super);
1394                 if (unlikely(!segbuf))
1395                         goto failed;
1396
1397                 /* map this buffer to region of segment on-disk */
1398                 nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1399                 sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1400
1401                 /* allocate the next next full segment */
1402                 err = nilfs_sufile_alloc(sufile, &nextnextnum);
1403                 if (unlikely(err))
1404                         goto failed_segbuf;
1405
1406                 segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1407                 nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1408
1409                 list_add_tail(&segbuf->sb_list, &list);
1410                 prev = segbuf;
1411         }
1412         list_splice(&list, sci->sc_segbufs.prev);
1413         return 0;
1414
1415  failed_segbuf:
1416         nilfs_segbuf_free(segbuf);
1417  failed:
1418         list_for_each_entry_safe(segbuf, n, &list, sb_list) {
1419                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1420                 WARN_ON(ret); /* never fails */
1421                 list_del_init(&segbuf->sb_list);
1422                 nilfs_segbuf_free(segbuf);
1423         }
1424         return err;
1425 }
1426
1427 static void nilfs_segctor_free_incomplete_segments(struct nilfs_sc_info *sci,
1428                                                    struct the_nilfs *nilfs)
1429 {
1430         struct nilfs_segment_buffer *segbuf;
1431         int ret, done = 0;
1432
1433         segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1434         if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1435                 ret = nilfs_sufile_free(nilfs->ns_sufile, segbuf->sb_nextnum);
1436                 WARN_ON(ret); /* never fails */
1437         }
1438         if (segbuf->sb_io_error) {
1439                 /* Case 1: The first segment failed */
1440                 if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1441                         /* Case 1a:  Partial segment appended into an existing
1442                            segment */
1443                         nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1444                                                 segbuf->sb_fseg_end);
1445                 else /* Case 1b:  New full segment */
1446                         set_nilfs_discontinued(nilfs);
1447                 done++;
1448         }
1449
1450         list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1451                 ret = nilfs_sufile_free(nilfs->ns_sufile, segbuf->sb_nextnum);
1452                 WARN_ON(ret); /* never fails */
1453                 if (!done && segbuf->sb_io_error) {
1454                         if (segbuf->sb_segnum != nilfs->ns_nextnum)
1455                                 /* Case 2: extended segment (!= next) failed */
1456                                 nilfs_sufile_set_error(nilfs->ns_sufile,
1457                                                        segbuf->sb_segnum);
1458                         done++;
1459                 }
1460         }
1461 }
1462
1463 static void nilfs_segctor_clear_segment_buffers(struct nilfs_sc_info *sci)
1464 {
1465         struct nilfs_segment_buffer *segbuf;
1466
1467         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list)
1468                 nilfs_segbuf_clear(segbuf);
1469         sci->sc_super_root = NULL;
1470 }
1471
1472 static void nilfs_segctor_destroy_segment_buffers(struct nilfs_sc_info *sci)
1473 {
1474         struct nilfs_segment_buffer *segbuf;
1475
1476         while (!list_empty(&sci->sc_segbufs)) {
1477                 segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1478                 list_del_init(&segbuf->sb_list);
1479                 nilfs_segbuf_free(segbuf);
1480         }
1481         /* sci->sc_curseg = NULL; */
1482 }
1483
1484 static void nilfs_segctor_end_construction(struct nilfs_sc_info *sci,
1485                                            struct the_nilfs *nilfs, int err)
1486 {
1487         if (unlikely(err)) {
1488                 nilfs_segctor_free_incomplete_segments(sci, nilfs);
1489                 nilfs_segctor_cancel_free_segments(sci, nilfs->ns_sufile);
1490         }
1491         nilfs_segctor_clear_segment_buffers(sci);
1492 }
1493
1494 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1495                                           struct inode *sufile)
1496 {
1497         struct nilfs_segment_buffer *segbuf;
1498         struct buffer_head *bh_su;
1499         struct nilfs_segment_usage *raw_su;
1500         unsigned long live_blocks;
1501         int ret;
1502
1503         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1504                 ret = nilfs_sufile_get_segment_usage(sufile, segbuf->sb_segnum,
1505                                                      &raw_su, &bh_su);
1506                 WARN_ON(ret); /* always succeed because bh_su is dirty */
1507                 live_blocks = segbuf->sb_sum.nblocks +
1508                         (segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1509                 raw_su->su_lastmod = cpu_to_le64(sci->sc_seg_ctime);
1510                 raw_su->su_nblocks = cpu_to_le32(live_blocks);
1511                 nilfs_sufile_put_segment_usage(sufile, segbuf->sb_segnum,
1512                                                bh_su);
1513         }
1514 }
1515
1516 static void nilfs_segctor_cancel_segusage(struct nilfs_sc_info *sci,
1517                                           struct inode *sufile)
1518 {
1519         struct nilfs_segment_buffer *segbuf;
1520         struct buffer_head *bh_su;
1521         struct nilfs_segment_usage *raw_su;
1522         int ret;
1523
1524         segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1525         ret = nilfs_sufile_get_segment_usage(sufile, segbuf->sb_segnum,
1526                                              &raw_su, &bh_su);
1527         WARN_ON(ret); /* always succeed because bh_su is dirty */
1528         raw_su->su_nblocks = cpu_to_le32(segbuf->sb_pseg_start -
1529                                          segbuf->sb_fseg_start);
1530         nilfs_sufile_put_segment_usage(sufile, segbuf->sb_segnum, bh_su);
1531
1532         list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1533                 ret = nilfs_sufile_get_segment_usage(sufile, segbuf->sb_segnum,
1534                                                      &raw_su, &bh_su);
1535                 WARN_ON(ret); /* always succeed */
1536                 raw_su->su_nblocks = 0;
1537                 nilfs_sufile_put_segment_usage(sufile, segbuf->sb_segnum,
1538                                                bh_su);
1539         }
1540 }
1541
1542 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1543                                             struct nilfs_segment_buffer *last,
1544                                             struct inode *sufile)
1545 {
1546         struct nilfs_segment_buffer *segbuf = last, *n;
1547         int ret;
1548
1549         list_for_each_entry_safe_continue(segbuf, n, &sci->sc_segbufs,
1550                                           sb_list) {
1551                 list_del_init(&segbuf->sb_list);
1552                 sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1553                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1554                 WARN_ON(ret);
1555                 nilfs_segbuf_free(segbuf);
1556         }
1557 }
1558
1559
1560 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1561                                  struct the_nilfs *nilfs, int mode)
1562 {
1563         struct nilfs_cstage prev_stage = sci->sc_stage;
1564         int err, nadd = 1;
1565
1566         /* Collection retry loop */
1567         for (;;) {
1568                 sci->sc_super_root = NULL;
1569                 sci->sc_nblk_this_inc = 0;
1570                 sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1571
1572                 err = nilfs_segctor_reset_segment_buffer(sci);
1573                 if (unlikely(err))
1574                         goto failed;
1575
1576                 err = nilfs_segctor_collect_blocks(sci, mode);
1577                 sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1578                 if (!err)
1579                         break;
1580
1581                 if (unlikely(err != -E2BIG))
1582                         goto failed;
1583
1584                 /* The current segment is filled up */
1585                 if (mode != SC_LSEG_SR || sci->sc_stage.scnt < NILFS_ST_CPFILE)
1586                         break;
1587
1588                 nilfs_segctor_cancel_free_segments(sci, nilfs->ns_sufile);
1589                 nilfs_segctor_clear_segment_buffers(sci);
1590
1591                 err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1592                 if (unlikely(err))
1593                         return err;
1594
1595                 nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1596                 sci->sc_stage = prev_stage;
1597         }
1598         nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1599         return 0;
1600
1601  failed:
1602         return err;
1603 }
1604
1605 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1606                                       struct buffer_head *new_bh)
1607 {
1608         BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1609
1610         list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1611         /* The caller must release old_bh */
1612 }
1613
1614 static int
1615 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1616                                      struct nilfs_segment_buffer *segbuf,
1617                                      int mode)
1618 {
1619         struct inode *inode = NULL;
1620         sector_t blocknr;
1621         unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1622         unsigned long nblocks = 0, ndatablk = 0;
1623         struct nilfs_sc_operations *sc_op = NULL;
1624         struct nilfs_segsum_pointer ssp;
1625         struct nilfs_finfo *finfo = NULL;
1626         union nilfs_binfo binfo;
1627         struct buffer_head *bh, *bh_org;
1628         ino_t ino = 0;
1629         int err = 0;
1630
1631         if (!nfinfo)
1632                 goto out;
1633
1634         blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1635         ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1636         ssp.offset = sizeof(struct nilfs_segment_summary);
1637
1638         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1639                 if (bh == sci->sc_super_root)
1640                         break;
1641                 if (!finfo) {
1642                         finfo = nilfs_segctor_map_segsum_entry(
1643                                 sci, &ssp, sizeof(*finfo));
1644                         ino = le64_to_cpu(finfo->fi_ino);
1645                         nblocks = le32_to_cpu(finfo->fi_nblocks);
1646                         ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1647
1648                         if (buffer_nilfs_node(bh))
1649                                 inode = NILFS_BTNC_I(bh->b_page->mapping);
1650                         else
1651                                 inode = NILFS_AS_I(bh->b_page->mapping);
1652
1653                         if (mode == SC_LSEG_DSYNC)
1654                                 sc_op = &nilfs_sc_dsync_ops;
1655                         else if (ino == NILFS_DAT_INO)
1656                                 sc_op = &nilfs_sc_dat_ops;
1657                         else /* file blocks */
1658                                 sc_op = &nilfs_sc_file_ops;
1659                 }
1660                 bh_org = bh;
1661                 get_bh(bh_org);
1662                 err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1663                                         &binfo);
1664                 if (bh != bh_org)
1665                         nilfs_list_replace_buffer(bh_org, bh);
1666                 brelse(bh_org);
1667                 if (unlikely(err))
1668                         goto failed_bmap;
1669
1670                 if (ndatablk > 0)
1671                         sc_op->write_data_binfo(sci, &ssp, &binfo);
1672                 else
1673                         sc_op->write_node_binfo(sci, &ssp, &binfo);
1674
1675                 blocknr++;
1676                 if (--nblocks == 0) {
1677                         finfo = NULL;
1678                         if (--nfinfo == 0)
1679                                 break;
1680                 } else if (ndatablk > 0)
1681                         ndatablk--;
1682         }
1683  out:
1684         return 0;
1685
1686  failed_bmap:
1687         err = nilfs_handle_bmap_error(err, __func__, inode, sci->sc_super);
1688         return err;
1689 }
1690
1691 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1692 {
1693         struct nilfs_segment_buffer *segbuf;
1694         int err;
1695
1696         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1697                 err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1698                 if (unlikely(err))
1699                         return err;
1700                 nilfs_segbuf_fill_in_segsum(segbuf);
1701         }
1702         return 0;
1703 }
1704
1705 static int
1706 nilfs_copy_replace_page_buffers(struct page *page, struct list_head *out)
1707 {
1708         struct page *clone_page;
1709         struct buffer_head *bh, *head, *bh2;
1710         void *kaddr;
1711
1712         bh = head = page_buffers(page);
1713
1714         clone_page = nilfs_alloc_private_page(bh->b_bdev, bh->b_size, 0);
1715         if (unlikely(!clone_page))
1716                 return -ENOMEM;
1717
1718         bh2 = page_buffers(clone_page);
1719         kaddr = kmap_atomic(page, KM_USER0);
1720         do {
1721                 if (list_empty(&bh->b_assoc_buffers))
1722                         continue;
1723                 get_bh(bh2);
1724                 page_cache_get(clone_page); /* for each bh */
1725                 memcpy(bh2->b_data, kaddr + bh_offset(bh), bh2->b_size);
1726                 bh2->b_blocknr = bh->b_blocknr;
1727                 list_replace(&bh->b_assoc_buffers, &bh2->b_assoc_buffers);
1728                 list_add_tail(&bh->b_assoc_buffers, out);
1729         } while (bh = bh->b_this_page, bh2 = bh2->b_this_page, bh != head);
1730         kunmap_atomic(kaddr, KM_USER0);
1731
1732         if (!TestSetPageWriteback(clone_page))
1733                 inc_zone_page_state(clone_page, NR_WRITEBACK);
1734         unlock_page(clone_page);
1735
1736         return 0;
1737 }
1738
1739 static int nilfs_test_page_to_be_frozen(struct page *page)
1740 {
1741         struct address_space *mapping = page->mapping;
1742
1743         if (!mapping || !mapping->host || S_ISDIR(mapping->host->i_mode))
1744                 return 0;
1745
1746         if (page_mapped(page)) {
1747                 ClearPageChecked(page);
1748                 return 1;
1749         }
1750         return PageChecked(page);
1751 }
1752
1753 static int nilfs_begin_page_io(struct page *page, struct list_head *out)
1754 {
1755         if (!page || PageWriteback(page))
1756                 /* For split b-tree node pages, this function may be called
1757                    twice.  We ignore the 2nd or later calls by this check. */
1758                 return 0;
1759
1760         lock_page(page);
1761         clear_page_dirty_for_io(page);
1762         set_page_writeback(page);
1763         unlock_page(page);
1764
1765         if (nilfs_test_page_to_be_frozen(page)) {
1766                 int err = nilfs_copy_replace_page_buffers(page, out);
1767                 if (unlikely(err))
1768                         return err;
1769         }
1770         return 0;
1771 }
1772
1773 static int nilfs_segctor_prepare_write(struct nilfs_sc_info *sci,
1774                                        struct page **failed_page)
1775 {
1776         struct nilfs_segment_buffer *segbuf;
1777         struct page *bd_page = NULL, *fs_page = NULL;
1778         struct list_head *list = &sci->sc_copied_buffers;
1779         int err;
1780
1781         *failed_page = NULL;
1782         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1783                 struct buffer_head *bh;
1784
1785                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1786                                     b_assoc_buffers) {
1787                         if (bh->b_page != bd_page) {
1788                                 if (bd_page) {
1789                                         lock_page(bd_page);
1790                                         clear_page_dirty_for_io(bd_page);
1791                                         set_page_writeback(bd_page);
1792                                         unlock_page(bd_page);
1793                                 }
1794                                 bd_page = bh->b_page;
1795                         }
1796                 }
1797
1798                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1799                                     b_assoc_buffers) {
1800                         if (bh == sci->sc_super_root) {
1801                                 if (bh->b_page != bd_page) {
1802                                         lock_page(bd_page);
1803                                         clear_page_dirty_for_io(bd_page);
1804                                         set_page_writeback(bd_page);
1805                                         unlock_page(bd_page);
1806                                         bd_page = bh->b_page;
1807                                 }
1808                                 break;
1809                         }
1810                         if (bh->b_page != fs_page) {
1811                                 err = nilfs_begin_page_io(fs_page, list);
1812                                 if (unlikely(err)) {
1813                                         *failed_page = fs_page;
1814                                         goto out;
1815                                 }
1816                                 fs_page = bh->b_page;
1817                         }
1818                 }
1819         }
1820         if (bd_page) {
1821                 lock_page(bd_page);
1822                 clear_page_dirty_for_io(bd_page);
1823                 set_page_writeback(bd_page);
1824                 unlock_page(bd_page);
1825         }
1826         err = nilfs_begin_page_io(fs_page, list);
1827         if (unlikely(err))
1828                 *failed_page = fs_page;
1829  out:
1830         return err;
1831 }
1832
1833 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1834                                struct backing_dev_info *bdi)
1835 {
1836         struct nilfs_segment_buffer *segbuf;
1837         struct nilfs_write_info wi;
1838         int err, res;
1839
1840         wi.sb = sci->sc_super;
1841         wi.bh_sr = sci->sc_super_root;
1842         wi.bdi = bdi;
1843
1844         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1845                 nilfs_segbuf_prepare_write(segbuf, &wi);
1846                 err = nilfs_segbuf_write(segbuf, &wi);
1847
1848                 res = nilfs_segbuf_wait(segbuf, &wi);
1849                 err = unlikely(err) ? : res;
1850                 if (unlikely(err))
1851                         return err;
1852         }
1853         return 0;
1854 }
1855
1856 static int nilfs_page_has_uncleared_buffer(struct page *page)
1857 {
1858         struct buffer_head *head, *bh;
1859
1860         head = bh = page_buffers(page);
1861         do {
1862                 if (buffer_dirty(bh) && !list_empty(&bh->b_assoc_buffers))
1863                         return 1;
1864                 bh = bh->b_this_page;
1865         } while (bh != head);
1866         return 0;
1867 }
1868
1869 static void __nilfs_end_page_io(struct page *page, int err)
1870 {
1871         if (!err) {
1872                 if (!nilfs_page_buffers_clean(page))
1873                         __set_page_dirty_nobuffers(page);
1874                 ClearPageError(page);
1875         } else {
1876                 __set_page_dirty_nobuffers(page);
1877                 SetPageError(page);
1878         }
1879
1880         if (buffer_nilfs_allocated(page_buffers(page))) {
1881                 if (TestClearPageWriteback(page))
1882                         dec_zone_page_state(page, NR_WRITEBACK);
1883         } else
1884                 end_page_writeback(page);
1885 }
1886
1887 static void nilfs_end_page_io(struct page *page, int err)
1888 {
1889         if (!page)
1890                 return;
1891
1892         if (buffer_nilfs_node(page_buffers(page)) &&
1893             nilfs_page_has_uncleared_buffer(page))
1894                 /* For b-tree node pages, this function may be called twice
1895                    or more because they might be split in a segment.
1896                    This check assures that cleanup has been done for all
1897                    buffers in a split btnode page. */
1898                 return;
1899
1900         __nilfs_end_page_io(page, err);
1901 }
1902
1903 static void nilfs_clear_copied_buffers(struct list_head *list, int err)
1904 {
1905         struct buffer_head *bh, *head;
1906         struct page *page;
1907
1908         while (!list_empty(list)) {
1909                 bh = list_entry(list->next, struct buffer_head,
1910                                 b_assoc_buffers);
1911                 page = bh->b_page;
1912                 page_cache_get(page);
1913                 head = bh = page_buffers(page);
1914                 do {
1915                         if (!list_empty(&bh->b_assoc_buffers)) {
1916                                 list_del_init(&bh->b_assoc_buffers);
1917                                 if (!err) {
1918                                         set_buffer_uptodate(bh);
1919                                         clear_buffer_dirty(bh);
1920                                         clear_buffer_nilfs_volatile(bh);
1921                                 }
1922                                 brelse(bh); /* for b_assoc_buffers */
1923                         }
1924                 } while ((bh = bh->b_this_page) != head);
1925
1926                 __nilfs_end_page_io(page, err);
1927                 page_cache_release(page);
1928         }
1929 }
1930
1931 static void nilfs_segctor_abort_write(struct nilfs_sc_info *sci,
1932                                       struct page *failed_page, int err)
1933 {
1934         struct nilfs_segment_buffer *segbuf;
1935         struct page *bd_page = NULL, *fs_page = NULL;
1936
1937         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1938                 struct buffer_head *bh;
1939
1940                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1941                                     b_assoc_buffers) {
1942                         if (bh->b_page != bd_page) {
1943                                 if (bd_page)
1944                                         end_page_writeback(bd_page);
1945                                 bd_page = bh->b_page;
1946                         }
1947                 }
1948
1949                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1950                                     b_assoc_buffers) {
1951                         if (bh == sci->sc_super_root) {
1952                                 if (bh->b_page != bd_page) {
1953                                         end_page_writeback(bd_page);
1954                                         bd_page = bh->b_page;
1955                                 }
1956                                 break;
1957                         }
1958                         if (bh->b_page != fs_page) {
1959                                 nilfs_end_page_io(fs_page, err);
1960                                 if (unlikely(fs_page == failed_page))
1961                                         goto done;
1962                                 fs_page = bh->b_page;
1963                         }
1964                 }
1965         }
1966         if (bd_page)
1967                 end_page_writeback(bd_page);
1968
1969         nilfs_end_page_io(fs_page, err);
1970  done:
1971         nilfs_clear_copied_buffers(&sci->sc_copied_buffers, err);
1972 }
1973
1974 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1975                                    struct nilfs_segment_buffer *segbuf)
1976 {
1977         nilfs->ns_segnum = segbuf->sb_segnum;
1978         nilfs->ns_nextnum = segbuf->sb_nextnum;
1979         nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1980                 + segbuf->sb_sum.nblocks;
1981         nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1982         nilfs->ns_ctime = segbuf->sb_sum.ctime;
1983 }
1984
1985 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1986 {
1987         struct nilfs_segment_buffer *segbuf;
1988         struct page *bd_page = NULL, *fs_page = NULL;
1989         struct nilfs_sb_info *sbi = sci->sc_sbi;
1990         struct the_nilfs *nilfs = sbi->s_nilfs;
1991         int update_sr = (sci->sc_super_root != NULL);
1992
1993         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1994                 struct buffer_head *bh;
1995
1996                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1997                                     b_assoc_buffers) {
1998                         set_buffer_uptodate(bh);
1999                         clear_buffer_dirty(bh);
2000                         if (bh->b_page != bd_page) {
2001                                 if (bd_page)
2002                                         end_page_writeback(bd_page);
2003                                 bd_page = bh->b_page;
2004                         }
2005                 }
2006                 /*
2007                  * We assume that the buffers which belong to the same page
2008                  * continue over the buffer list.
2009                  * Under this assumption, the last BHs of pages is
2010                  * identifiable by the discontinuity of bh->b_page
2011                  * (page != fs_page).
2012                  *
2013                  * For B-tree node blocks, however, this assumption is not
2014                  * guaranteed.  The cleanup code of B-tree node pages needs
2015                  * special care.
2016                  */
2017                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
2018                                     b_assoc_buffers) {
2019                         set_buffer_uptodate(bh);
2020                         clear_buffer_dirty(bh);
2021                         clear_buffer_nilfs_volatile(bh);
2022                         if (bh == sci->sc_super_root) {
2023                                 if (bh->b_page != bd_page) {
2024                                         end_page_writeback(bd_page);
2025                                         bd_page = bh->b_page;
2026                                 }
2027                                 break;
2028                         }
2029                         if (bh->b_page != fs_page) {
2030                                 nilfs_end_page_io(fs_page, 0);
2031                                 fs_page = bh->b_page;
2032                         }
2033                 }
2034
2035                 if (!NILFS_SEG_SIMPLEX(&segbuf->sb_sum)) {
2036                         if (NILFS_SEG_LOGBGN(&segbuf->sb_sum)) {
2037                                 set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
2038                                 sci->sc_lseg_stime = jiffies;
2039                         }
2040                         if (NILFS_SEG_LOGEND(&segbuf->sb_sum))
2041                                 clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
2042                 }
2043         }
2044         /*
2045          * Since pages may continue over multiple segment buffers,
2046          * end of the last page must be checked outside of the loop.
2047          */
2048         if (bd_page)
2049                 end_page_writeback(bd_page);
2050
2051         nilfs_end_page_io(fs_page, 0);
2052
2053         nilfs_clear_copied_buffers(&sci->sc_copied_buffers, 0);
2054
2055         nilfs_drop_collected_inodes(&sci->sc_dirty_files);
2056
2057         if (nilfs_doing_gc()) {
2058                 nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
2059                 if (update_sr)
2060                         nilfs_commit_gcdat_inode(nilfs);
2061         } else
2062                 nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
2063
2064         sci->sc_nblk_inc += sci->sc_nblk_this_inc;
2065
2066         segbuf = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
2067         nilfs_set_next_segment(nilfs, segbuf);
2068
2069         if (update_sr) {
2070                 nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
2071                                        segbuf->sb_sum.seg_seq, nilfs->ns_cno);
2072
2073                 clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
2074                 clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2075                 set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
2076         } else
2077                 clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
2078 }
2079
2080 static int nilfs_segctor_check_in_files(struct nilfs_sc_info *sci,
2081                                         struct nilfs_sb_info *sbi)
2082 {
2083         struct nilfs_inode_info *ii, *n;
2084         __u64 cno = sbi->s_nilfs->ns_cno;
2085
2086         spin_lock(&sbi->s_inode_lock);
2087  retry:
2088         list_for_each_entry_safe(ii, n, &sbi->s_dirty_files, i_dirty) {
2089                 if (!ii->i_bh) {
2090                         struct buffer_head *ibh;
2091                         int err;
2092
2093                         spin_unlock(&sbi->s_inode_lock);
2094                         err = nilfs_ifile_get_inode_block(
2095                                 sbi->s_ifile, ii->vfs_inode.i_ino, &ibh);
2096                         if (unlikely(err)) {
2097                                 nilfs_warning(sbi->s_super, __func__,
2098                                               "failed to get inode block.\n");
2099                                 return err;
2100                         }
2101                         nilfs_mdt_mark_buffer_dirty(ibh);
2102                         nilfs_mdt_mark_dirty(sbi->s_ifile);
2103                         spin_lock(&sbi->s_inode_lock);
2104                         if (likely(!ii->i_bh))
2105                                 ii->i_bh = ibh;
2106                         else
2107                                 brelse(ibh);
2108                         goto retry;
2109                 }
2110                 ii->i_cno = cno;
2111
2112                 clear_bit(NILFS_I_QUEUED, &ii->i_state);
2113                 set_bit(NILFS_I_BUSY, &ii->i_state);
2114                 list_del(&ii->i_dirty);
2115                 list_add_tail(&ii->i_dirty, &sci->sc_dirty_files);
2116         }
2117         spin_unlock(&sbi->s_inode_lock);
2118
2119         NILFS_I(sbi->s_ifile)->i_cno = cno;
2120
2121         return 0;
2122 }
2123
2124 static void nilfs_segctor_check_out_files(struct nilfs_sc_info *sci,
2125                                           struct nilfs_sb_info *sbi)
2126 {
2127         struct nilfs_transaction_info *ti = current->journal_info;
2128         struct nilfs_inode_info *ii, *n;
2129         __u64 cno = sbi->s_nilfs->ns_cno;
2130
2131         spin_lock(&sbi->s_inode_lock);
2132         list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
2133                 if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
2134                     test_bit(NILFS_I_DIRTY, &ii->i_state)) {
2135                         /* The current checkpoint number (=nilfs->ns_cno) is
2136                            changed between check-in and check-out only if the
2137                            super root is written out.  So, we can update i_cno
2138                            for the inodes that remain in the dirty list. */
2139                         ii->i_cno = cno;
2140                         continue;
2141                 }
2142                 clear_bit(NILFS_I_BUSY, &ii->i_state);
2143                 brelse(ii->i_bh);
2144                 ii->i_bh = NULL;
2145                 list_del(&ii->i_dirty);
2146                 list_add_tail(&ii->i_dirty, &ti->ti_garbage);
2147         }
2148         spin_unlock(&sbi->s_inode_lock);
2149 }
2150
2151 /*
2152  * Main procedure of segment constructor
2153  */
2154 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
2155 {
2156         struct nilfs_sb_info *sbi = sci->sc_sbi;
2157         struct the_nilfs *nilfs = sbi->s_nilfs;
2158         struct page *failed_page;
2159         int err, has_sr = 0;
2160
2161         sci->sc_stage.scnt = NILFS_ST_INIT;
2162
2163         err = nilfs_segctor_check_in_files(sci, sbi);
2164         if (unlikely(err))
2165                 goto out;
2166
2167         if (nilfs_test_metadata_dirty(sbi))
2168                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2169
2170         if (nilfs_segctor_clean(sci))
2171                 goto out;
2172
2173         do {
2174                 sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
2175
2176                 err = nilfs_segctor_begin_construction(sci, nilfs);
2177                 if (unlikely(err))
2178                         goto out;
2179
2180                 /* Update time stamp */
2181                 sci->sc_seg_ctime = get_seconds();
2182
2183                 err = nilfs_segctor_collect(sci, nilfs, mode);
2184                 if (unlikely(err))
2185                         goto failed;
2186
2187                 has_sr = (sci->sc_super_root != NULL);
2188
2189                 /* Avoid empty segment */
2190                 if (sci->sc_stage.scnt == NILFS_ST_DONE &&
2191                     NILFS_SEG_EMPTY(&sci->sc_curseg->sb_sum)) {
2192                         nilfs_segctor_end_construction(sci, nilfs, 1);
2193                         goto out;
2194                 }
2195
2196                 err = nilfs_segctor_assign(sci, mode);
2197                 if (unlikely(err))
2198                         goto failed;
2199
2200                 if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2201                         nilfs_segctor_fill_in_file_bmap(sci, sbi->s_ifile);
2202
2203                 if (has_sr) {
2204                         err = nilfs_segctor_fill_in_checkpoint(sci);
2205                         if (unlikely(err))
2206                                 goto failed_to_make_up;
2207
2208                         nilfs_segctor_fill_in_super_root(sci, nilfs);
2209                 }
2210                 nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2211
2212                 /* Write partial segments */
2213                 err = nilfs_segctor_prepare_write(sci, &failed_page);
2214                 if (unlikely(err))
2215                         goto failed_to_write;
2216
2217                 nilfs_segctor_fill_in_checksums(sci, nilfs->ns_crc_seed);
2218
2219                 err = nilfs_segctor_write(sci, nilfs->ns_bdi);
2220                 if (unlikely(err))
2221                         goto failed_to_write;
2222
2223                 nilfs_segctor_complete_write(sci);
2224
2225                 /* Commit segments */
2226                 if (has_sr) {
2227                         down_write(&nilfs->ns_sem);
2228                         nilfs_update_last_segment(sbi, 1);
2229                         up_write(&nilfs->ns_sem);
2230                         nilfs_segctor_commit_free_segments(sci);
2231                         nilfs_segctor_clear_metadata_dirty(sci);
2232                 }
2233
2234                 nilfs_segctor_end_construction(sci, nilfs, 0);
2235
2236         } while (sci->sc_stage.scnt != NILFS_ST_DONE);
2237
2238  out:
2239         nilfs_segctor_destroy_segment_buffers(sci);
2240         nilfs_segctor_check_out_files(sci, sbi);
2241         return err;
2242
2243  failed_to_write:
2244         nilfs_segctor_abort_write(sci, failed_page, err);
2245         nilfs_segctor_cancel_segusage(sci, nilfs->ns_sufile);
2246
2247  failed_to_make_up:
2248         if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2249                 nilfs_redirty_inodes(&sci->sc_dirty_files);
2250
2251  failed:
2252         if (nilfs_doing_gc())
2253                 nilfs_redirty_inodes(&sci->sc_gc_inodes);
2254         nilfs_segctor_end_construction(sci, nilfs, err);
2255         goto out;
2256 }
2257
2258 /**
2259  * nilfs_secgtor_start_timer - set timer of background write
2260  * @sci: nilfs_sc_info
2261  *
2262  * If the timer has already been set, it ignores the new request.
2263  * This function MUST be called within a section locking the segment
2264  * semaphore.
2265  */
2266 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2267 {
2268         spin_lock(&sci->sc_state_lock);
2269         if (sci->sc_timer && !(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2270                 sci->sc_timer->expires = jiffies + sci->sc_interval;
2271                 add_timer(sci->sc_timer);
2272                 sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2273         }
2274         spin_unlock(&sci->sc_state_lock);
2275 }
2276
2277 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2278 {
2279         spin_lock(&sci->sc_state_lock);
2280         if (!(sci->sc_flush_request & (1 << bn))) {
2281                 unsigned long prev_req = sci->sc_flush_request;
2282
2283                 sci->sc_flush_request |= (1 << bn);
2284                 if (!prev_req)
2285                         wake_up(&sci->sc_wait_daemon);
2286         }
2287         spin_unlock(&sci->sc_state_lock);
2288 }
2289
2290 /**
2291  * nilfs_flush_segment - trigger a segment construction for resource control
2292  * @sb: super block
2293  * @ino: inode number of the file to be flushed out.
2294  */
2295 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2296 {
2297         struct nilfs_sb_info *sbi = NILFS_SB(sb);
2298         struct nilfs_sc_info *sci = NILFS_SC(sbi);
2299
2300         if (!sci || nilfs_doing_construction())
2301                 return;
2302         nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2303                                         /* assign bit 0 to data files */
2304 }
2305
2306 int nilfs_segctor_add_segments_to_be_freed(struct nilfs_sc_info *sci,
2307                                            __u64 *segnum, size_t nsegs)
2308 {
2309         struct nilfs_segment_entry *ent;
2310         struct the_nilfs *nilfs = sci->sc_sbi->s_nilfs;
2311         struct inode *sufile = nilfs->ns_sufile;
2312         LIST_HEAD(list);
2313         __u64 *pnum;
2314         size_t i;
2315         int err;
2316
2317         for (pnum = segnum, i = 0; i < nsegs; pnum++, i++) {
2318                 ent = nilfs_alloc_segment_entry(*pnum);
2319                 if (unlikely(!ent)) {
2320                         err = -ENOMEM;
2321                         goto failed;
2322                 }
2323                 list_add_tail(&ent->list, &list);
2324
2325                 err = nilfs_open_segment_entry(ent, sufile);
2326                 if (unlikely(err))
2327                         goto failed;
2328
2329                 if (unlikely(!nilfs_segment_usage_dirty(ent->raw_su)))
2330                         printk(KERN_WARNING "NILFS: unused segment is "
2331                                "requested to be cleaned (segnum=%llu)\n",
2332                                (unsigned long long)ent->segnum);
2333                 nilfs_close_segment_entry(ent, sufile);
2334         }
2335         list_splice(&list, sci->sc_cleaning_segments.prev);
2336         return 0;
2337
2338  failed:
2339         nilfs_dispose_segment_list(&list);
2340         return err;
2341 }
2342
2343 void nilfs_segctor_clear_segments_to_be_freed(struct nilfs_sc_info *sci)
2344 {
2345         nilfs_dispose_segment_list(&sci->sc_cleaning_segments);
2346 }
2347
2348 struct nilfs_segctor_wait_request {
2349         wait_queue_t    wq;
2350         __u32           seq;
2351         int             err;
2352         atomic_t        done;
2353 };
2354
2355 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2356 {
2357         struct nilfs_segctor_wait_request wait_req;
2358         int err = 0;
2359
2360         spin_lock(&sci->sc_state_lock);
2361         init_wait(&wait_req.wq);
2362         wait_req.err = 0;
2363         atomic_set(&wait_req.done, 0);
2364         wait_req.seq = ++sci->sc_seq_request;
2365         spin_unlock(&sci->sc_state_lock);
2366
2367         init_waitqueue_entry(&wait_req.wq, current);
2368         add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2369         set_current_state(TASK_INTERRUPTIBLE);
2370         wake_up(&sci->sc_wait_daemon);
2371
2372         for (;;) {
2373                 if (atomic_read(&wait_req.done)) {
2374                         err = wait_req.err;
2375                         break;
2376                 }
2377                 if (!signal_pending(current)) {
2378                         schedule();
2379                         continue;
2380                 }
2381                 err = -ERESTARTSYS;
2382                 break;
2383         }
2384         finish_wait(&sci->sc_wait_request, &wait_req.wq);
2385         return err;
2386 }
2387
2388 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2389 {
2390         struct nilfs_segctor_wait_request *wrq, *n;
2391         unsigned long flags;
2392
2393         spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2394         list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.task_list,
2395                                  wq.task_list) {
2396                 if (!atomic_read(&wrq->done) &&
2397                     nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2398                         wrq->err = err;
2399                         atomic_set(&wrq->done, 1);
2400                 }
2401                 if (atomic_read(&wrq->done)) {
2402                         wrq->wq.func(&wrq->wq,
2403                                      TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2404                                      0, NULL);
2405                 }
2406         }
2407         spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2408 }
2409
2410 /**
2411  * nilfs_construct_segment - construct a logical segment
2412  * @sb: super block
2413  *
2414  * Return Value: On success, 0 is retured. On errors, one of the following
2415  * negative error code is returned.
2416  *
2417  * %-EROFS - Read only filesystem.
2418  *
2419  * %-EIO - I/O error
2420  *
2421  * %-ENOSPC - No space left on device (only in a panic state).
2422  *
2423  * %-ERESTARTSYS - Interrupted.
2424  *
2425  * %-ENOMEM - Insufficient memory available.
2426  */
2427 int nilfs_construct_segment(struct super_block *sb)
2428 {
2429         struct nilfs_sb_info *sbi = NILFS_SB(sb);
2430         struct nilfs_sc_info *sci = NILFS_SC(sbi);
2431         struct nilfs_transaction_info *ti;
2432         int err;
2433
2434         if (!sci)
2435                 return -EROFS;
2436
2437         /* A call inside transactions causes a deadlock. */
2438         BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2439
2440         err = nilfs_segctor_sync(sci);
2441         return err;
2442 }
2443
2444 /**
2445  * nilfs_construct_dsync_segment - construct a data-only logical segment
2446  * @sb: super block
2447  * @inode: inode whose data blocks should be written out
2448  * @start: start byte offset
2449  * @end: end byte offset (inclusive)
2450  *
2451  * Return Value: On success, 0 is retured. On errors, one of the following
2452  * negative error code is returned.
2453  *
2454  * %-EROFS - Read only filesystem.
2455  *
2456  * %-EIO - I/O error
2457  *
2458  * %-ENOSPC - No space left on device (only in a panic state).
2459  *
2460  * %-ERESTARTSYS - Interrupted.
2461  *
2462  * %-ENOMEM - Insufficient memory available.
2463  */
2464 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2465                                   loff_t start, loff_t end)
2466 {
2467         struct nilfs_sb_info *sbi = NILFS_SB(sb);
2468         struct nilfs_sc_info *sci = NILFS_SC(sbi);
2469         struct nilfs_inode_info *ii;
2470         struct nilfs_transaction_info ti;
2471         int err = 0;
2472
2473         if (!sci)
2474                 return -EROFS;
2475
2476         nilfs_transaction_lock(sbi, &ti, 0);
2477
2478         ii = NILFS_I(inode);
2479         if (test_bit(NILFS_I_INODE_DIRTY, &ii->i_state) ||
2480             nilfs_test_opt(sbi, STRICT_ORDER) ||
2481             test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2482             nilfs_discontinued(sbi->s_nilfs)) {
2483                 nilfs_transaction_unlock(sbi);
2484                 err = nilfs_segctor_sync(sci);
2485                 return err;
2486         }
2487
2488         spin_lock(&sbi->s_inode_lock);
2489         if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2490             !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2491                 spin_unlock(&sbi->s_inode_lock);
2492                 nilfs_transaction_unlock(sbi);
2493                 return 0;
2494         }
2495         spin_unlock(&sbi->s_inode_lock);
2496         sci->sc_dsync_inode = ii;
2497         sci->sc_dsync_start = start;
2498         sci->sc_dsync_end = end;
2499
2500         err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2501
2502         nilfs_transaction_unlock(sbi);
2503         return err;
2504 }
2505
2506 struct nilfs_segctor_req {
2507         int mode;
2508         __u32 seq_accepted;
2509         int sc_err;  /* construction failure */
2510         int sb_err;  /* super block writeback failure */
2511 };
2512
2513 #define FLUSH_FILE_BIT  (0x1) /* data file only */
2514 #define FLUSH_DAT_BIT   (1 << NILFS_DAT_INO) /* DAT only */
2515
2516 static void nilfs_segctor_accept(struct nilfs_sc_info *sci,
2517                                  struct nilfs_segctor_req *req)
2518 {
2519         req->sc_err = req->sb_err = 0;
2520         spin_lock(&sci->sc_state_lock);
2521         req->seq_accepted = sci->sc_seq_request;
2522         spin_unlock(&sci->sc_state_lock);
2523
2524         if (sci->sc_timer)
2525                 del_timer_sync(sci->sc_timer);
2526 }
2527
2528 static void nilfs_segctor_notify(struct nilfs_sc_info *sci,
2529                                  struct nilfs_segctor_req *req)
2530 {
2531         /* Clear requests (even when the construction failed) */
2532         spin_lock(&sci->sc_state_lock);
2533
2534         sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2535
2536         if (req->mode == SC_LSEG_SR) {
2537                 sci->sc_seq_done = req->seq_accepted;
2538                 nilfs_segctor_wakeup(sci, req->sc_err ? : req->sb_err);
2539                 sci->sc_flush_request = 0;
2540         } else if (req->mode == SC_FLUSH_FILE)
2541                 sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2542         else if (req->mode == SC_FLUSH_DAT)
2543                 sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2544
2545         spin_unlock(&sci->sc_state_lock);
2546 }
2547
2548 static int nilfs_segctor_construct(struct nilfs_sc_info *sci,
2549                                    struct nilfs_segctor_req *req)
2550 {
2551         struct nilfs_sb_info *sbi = sci->sc_sbi;
2552         struct the_nilfs *nilfs = sbi->s_nilfs;
2553         int err = 0;
2554
2555         if (nilfs_discontinued(nilfs))
2556                 req->mode = SC_LSEG_SR;
2557         if (!nilfs_segctor_confirm(sci)) {
2558                 err = nilfs_segctor_do_construct(sci, req->mode);
2559                 req->sc_err = err;
2560         }
2561         if (likely(!err)) {
2562                 if (req->mode != SC_FLUSH_DAT)
2563                         atomic_set(&nilfs->ns_ndirtyblks, 0);
2564                 if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2565                     nilfs_discontinued(nilfs)) {
2566                         down_write(&nilfs->ns_sem);
2567                         req->sb_err = nilfs_commit_super(sbi);
2568                         up_write(&nilfs->ns_sem);
2569                 }
2570         }
2571         return err;
2572 }
2573
2574 static void nilfs_construction_timeout(unsigned long data)
2575 {
2576         struct task_struct *p = (struct task_struct *)data;
2577         wake_up_process(p);
2578 }
2579
2580 static void
2581 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2582 {
2583         struct nilfs_inode_info *ii, *n;
2584
2585         list_for_each_entry_safe(ii, n, head, i_dirty) {
2586                 if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2587                         continue;
2588                 hlist_del_init(&ii->vfs_inode.i_hash);
2589                 list_del_init(&ii->i_dirty);
2590                 nilfs_clear_gcinode(&ii->vfs_inode);
2591         }
2592 }
2593
2594 int nilfs_clean_segments(struct super_block *sb, void __user *argp)
2595 {
2596         struct nilfs_sb_info *sbi = NILFS_SB(sb);
2597         struct nilfs_sc_info *sci = NILFS_SC(sbi);
2598         struct the_nilfs *nilfs = sbi->s_nilfs;
2599         struct nilfs_transaction_info ti;
2600         struct nilfs_segctor_req req = { .mode = SC_LSEG_SR };
2601         int err;
2602
2603         if (unlikely(!sci))
2604                 return -EROFS;
2605
2606         nilfs_transaction_lock(sbi, &ti, 1);
2607
2608         err = nilfs_init_gcdat_inode(nilfs);
2609         if (unlikely(err))
2610                 goto out_unlock;
2611         err = nilfs_ioctl_prepare_clean_segments(nilfs, argp);
2612         if (unlikely(err))
2613                 goto out_unlock;
2614
2615         list_splice_init(&nilfs->ns_gc_inodes, sci->sc_gc_inodes.prev);
2616
2617         for (;;) {
2618                 nilfs_segctor_accept(sci, &req);
2619                 err = nilfs_segctor_construct(sci, &req);
2620                 nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2621                 nilfs_segctor_notify(sci, &req);
2622
2623                 if (likely(!err))
2624                         break;
2625
2626                 nilfs_warning(sb, __func__,
2627                               "segment construction failed. (err=%d)", err);
2628                 set_current_state(TASK_INTERRUPTIBLE);
2629                 schedule_timeout(sci->sc_interval);
2630         }
2631
2632  out_unlock:
2633         nilfs_clear_gcdat_inode(nilfs);
2634         nilfs_transaction_unlock(sbi);
2635         return err;
2636 }
2637
2638 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2639 {
2640         struct nilfs_sb_info *sbi = sci->sc_sbi;
2641         struct nilfs_transaction_info ti;
2642         struct nilfs_segctor_req req = { .mode = mode };
2643
2644         nilfs_transaction_lock(sbi, &ti, 0);
2645
2646         nilfs_segctor_accept(sci, &req);
2647         nilfs_segctor_construct(sci, &req);
2648         nilfs_segctor_notify(sci, &req);
2649
2650         /*
2651          * Unclosed segment should be retried.  We do this using sc_timer.
2652          * Timeout of sc_timer will invoke complete construction which leads
2653          * to close the current logical segment.
2654          */
2655         if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2656                 nilfs_segctor_start_timer(sci);
2657
2658         nilfs_transaction_unlock(sbi);
2659 }
2660
2661 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2662 {
2663         int mode = 0;
2664         int err;
2665
2666         spin_lock(&sci->sc_state_lock);
2667         mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2668                 SC_FLUSH_DAT : SC_FLUSH_FILE;
2669         spin_unlock(&sci->sc_state_lock);
2670
2671         if (mode) {
2672                 err = nilfs_segctor_do_construct(sci, mode);
2673
2674                 spin_lock(&sci->sc_state_lock);
2675                 sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2676                         ~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2677                 spin_unlock(&sci->sc_state_lock);
2678         }
2679         clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2680 }
2681
2682 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2683 {
2684         if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2685             time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2686                 if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2687                         return SC_FLUSH_FILE;
2688                 else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2689                         return SC_FLUSH_DAT;
2690         }
2691         return SC_LSEG_SR;
2692 }
2693
2694 /**
2695  * nilfs_segctor_thread - main loop of the segment constructor thread.
2696  * @arg: pointer to a struct nilfs_sc_info.
2697  *
2698  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2699  * to execute segment constructions.
2700  */
2701 static int nilfs_segctor_thread(void *arg)
2702 {
2703         struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2704         struct timer_list timer;
2705         int timeout = 0;
2706
2707         init_timer(&timer);
2708         timer.data = (unsigned long)current;
2709         timer.function = nilfs_construction_timeout;
2710         sci->sc_timer = &timer;
2711
2712         /* start sync. */
2713         sci->sc_task = current;
2714         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2715         printk(KERN_INFO
2716                "segctord starting. Construction interval = %lu seconds, "
2717                "CP frequency < %lu seconds\n",
2718                sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2719
2720         spin_lock(&sci->sc_state_lock);
2721  loop:
2722         for (;;) {
2723                 int mode;
2724
2725                 if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2726                         goto end_thread;
2727
2728                 if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2729                         mode = SC_LSEG_SR;
2730                 else if (!sci->sc_flush_request)
2731                         break;
2732                 else
2733                         mode = nilfs_segctor_flush_mode(sci);
2734
2735                 spin_unlock(&sci->sc_state_lock);
2736                 nilfs_segctor_thread_construct(sci, mode);
2737                 spin_lock(&sci->sc_state_lock);
2738                 timeout = 0;
2739         }
2740
2741
2742         if (freezing(current)) {
2743                 spin_unlock(&sci->sc_state_lock);
2744                 refrigerator();
2745                 spin_lock(&sci->sc_state_lock);
2746         } else {
2747                 DEFINE_WAIT(wait);
2748                 int should_sleep = 1;
2749
2750                 prepare_to_wait(&sci->sc_wait_daemon, &wait,
2751                                 TASK_INTERRUPTIBLE);
2752
2753                 if (sci->sc_seq_request != sci->sc_seq_done)
2754                         should_sleep = 0;
2755                 else if (sci->sc_flush_request)
2756                         should_sleep = 0;
2757                 else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2758                         should_sleep = time_before(jiffies,
2759                                                    sci->sc_timer->expires);
2760
2761                 if (should_sleep) {
2762                         spin_unlock(&sci->sc_state_lock);
2763                         schedule();
2764                         spin_lock(&sci->sc_state_lock);
2765                 }
2766                 finish_wait(&sci->sc_wait_daemon, &wait);
2767                 timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2768                            time_after_eq(jiffies, sci->sc_timer->expires));
2769         }
2770         goto loop;
2771
2772  end_thread:
2773         spin_unlock(&sci->sc_state_lock);
2774         del_timer_sync(sci->sc_timer);
2775         sci->sc_timer = NULL;
2776
2777         /* end sync. */
2778         sci->sc_task = NULL;
2779         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2780         return 0;
2781 }
2782
2783 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2784 {
2785         struct task_struct *t;
2786
2787         t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2788         if (IS_ERR(t)) {
2789                 int err = PTR_ERR(t);
2790
2791                 printk(KERN_ERR "NILFS: error %d creating segctord thread\n",
2792                        err);
2793                 return err;
2794         }
2795         wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2796         return 0;
2797 }
2798
2799 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2800 {
2801         sci->sc_state |= NILFS_SEGCTOR_QUIT;
2802
2803         while (sci->sc_task) {
2804                 wake_up(&sci->sc_wait_daemon);
2805                 spin_unlock(&sci->sc_state_lock);
2806                 wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2807                 spin_lock(&sci->sc_state_lock);
2808         }
2809 }
2810
2811 static int nilfs_segctor_init(struct nilfs_sc_info *sci)
2812 {
2813         sci->sc_seq_done = sci->sc_seq_request;
2814
2815         return nilfs_segctor_start_thread(sci);
2816 }
2817
2818 /*
2819  * Setup & clean-up functions
2820  */
2821 static struct nilfs_sc_info *nilfs_segctor_new(struct nilfs_sb_info *sbi)
2822 {
2823         struct nilfs_sc_info *sci;
2824
2825         sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2826         if (!sci)
2827                 return NULL;
2828
2829         sci->sc_sbi = sbi;
2830         sci->sc_super = sbi->s_super;
2831
2832         init_waitqueue_head(&sci->sc_wait_request);
2833         init_waitqueue_head(&sci->sc_wait_daemon);
2834         init_waitqueue_head(&sci->sc_wait_task);
2835         spin_lock_init(&sci->sc_state_lock);
2836         INIT_LIST_HEAD(&sci->sc_dirty_files);
2837         INIT_LIST_HEAD(&sci->sc_segbufs);
2838         INIT_LIST_HEAD(&sci->sc_gc_inodes);
2839         INIT_LIST_HEAD(&sci->sc_cleaning_segments);
2840         INIT_LIST_HEAD(&sci->sc_copied_buffers);
2841
2842         sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2843         sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2844         sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2845
2846         if (sbi->s_interval)
2847                 sci->sc_interval = sbi->s_interval;
2848         if (sbi->s_watermark)
2849                 sci->sc_watermark = sbi->s_watermark;
2850         return sci;
2851 }
2852
2853 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2854 {
2855         int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2856
2857         /* The segctord thread was stopped and its timer was removed.
2858            But some tasks remain. */
2859         do {
2860                 struct nilfs_sb_info *sbi = sci->sc_sbi;
2861                 struct nilfs_transaction_info ti;
2862                 struct nilfs_segctor_req req = { .mode = SC_LSEG_SR };
2863
2864                 nilfs_transaction_lock(sbi, &ti, 0);
2865                 nilfs_segctor_accept(sci, &req);
2866                 ret = nilfs_segctor_construct(sci, &req);
2867                 nilfs_segctor_notify(sci, &req);
2868                 nilfs_transaction_unlock(sbi);
2869
2870         } while (ret && retrycount-- > 0);
2871 }
2872
2873 /**
2874  * nilfs_segctor_destroy - destroy the segment constructor.
2875  * @sci: nilfs_sc_info
2876  *
2877  * nilfs_segctor_destroy() kills the segctord thread and frees
2878  * the nilfs_sc_info struct.
2879  * Caller must hold the segment semaphore.
2880  */
2881 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2882 {
2883         struct nilfs_sb_info *sbi = sci->sc_sbi;
2884         int flag;
2885
2886         up_write(&sbi->s_nilfs->ns_segctor_sem);
2887
2888         spin_lock(&sci->sc_state_lock);
2889         nilfs_segctor_kill_thread(sci);
2890         flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2891                 || sci->sc_seq_request != sci->sc_seq_done);
2892         spin_unlock(&sci->sc_state_lock);
2893
2894         if (flag || nilfs_segctor_confirm(sci))
2895                 nilfs_segctor_write_out(sci);
2896
2897         WARN_ON(!list_empty(&sci->sc_copied_buffers));
2898
2899         if (!list_empty(&sci->sc_dirty_files)) {
2900                 nilfs_warning(sbi->s_super, __func__,
2901                               "dirty file(s) after the final construction\n");
2902                 nilfs_dispose_list(sbi, &sci->sc_dirty_files, 1);
2903         }
2904
2905         if (!list_empty(&sci->sc_cleaning_segments))
2906                 nilfs_dispose_segment_list(&sci->sc_cleaning_segments);
2907
2908         WARN_ON(!list_empty(&sci->sc_segbufs));
2909
2910         down_write(&sbi->s_nilfs->ns_segctor_sem);
2911
2912         kfree(sci);
2913 }
2914
2915 /**
2916  * nilfs_attach_segment_constructor - attach a segment constructor
2917  * @sbi: nilfs_sb_info
2918  *
2919  * nilfs_attach_segment_constructor() allocates a struct nilfs_sc_info,
2920  * initilizes it, and starts the segment constructor.
2921  *
2922  * Return Value: On success, 0 is returned. On error, one of the following
2923  * negative error code is returned.
2924  *
2925  * %-ENOMEM - Insufficient memory available.
2926  */
2927 int nilfs_attach_segment_constructor(struct nilfs_sb_info *sbi)
2928 {
2929         struct the_nilfs *nilfs = sbi->s_nilfs;
2930         int err;
2931
2932         /* Each field of nilfs_segctor is cleared through the initialization
2933            of super-block info */
2934         sbi->s_sc_info = nilfs_segctor_new(sbi);
2935         if (!sbi->s_sc_info)
2936                 return -ENOMEM;
2937
2938         nilfs_attach_writer(nilfs, sbi);
2939         err = nilfs_segctor_init(NILFS_SC(sbi));
2940         if (err) {
2941                 nilfs_detach_writer(nilfs, sbi);
2942                 kfree(sbi->s_sc_info);
2943                 sbi->s_sc_info = NULL;
2944         }
2945         return err;
2946 }
2947
2948 /**
2949  * nilfs_detach_segment_constructor - destroy the segment constructor
2950  * @sbi: nilfs_sb_info
2951  *
2952  * nilfs_detach_segment_constructor() kills the segment constructor daemon,
2953  * frees the struct nilfs_sc_info, and destroy the dirty file list.
2954  */
2955 void nilfs_detach_segment_constructor(struct nilfs_sb_info *sbi)
2956 {
2957         struct the_nilfs *nilfs = sbi->s_nilfs;
2958         LIST_HEAD(garbage_list);
2959
2960         down_write(&nilfs->ns_segctor_sem);
2961         if (NILFS_SC(sbi)) {
2962                 nilfs_segctor_destroy(NILFS_SC(sbi));
2963                 sbi->s_sc_info = NULL;
2964         }
2965
2966         /* Force to free the list of dirty files */
2967         spin_lock(&sbi->s_inode_lock);
2968         if (!list_empty(&sbi->s_dirty_files)) {
2969                 list_splice_init(&sbi->s_dirty_files, &garbage_list);
2970                 nilfs_warning(sbi->s_super, __func__,
2971                               "Non empty dirty list after the last "
2972                               "segment construction\n");
2973         }
2974         spin_unlock(&sbi->s_inode_lock);
2975         up_write(&nilfs->ns_segctor_sem);
2976
2977         nilfs_dispose_list(sbi, &garbage_list, 1);
2978         nilfs_detach_writer(nilfs, sbi);
2979 }