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  * Written by Ryusuke Konishi.
  17  *
  18  */
  19
  20 #include <linux/pagemap.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/writeback.h>
  23 #include <linux/bitops.h>
  24 #include <linux/bio.h>
  25 #include <linux/completion.h>
  26 #include <linux/blkdev.h>
  27 #include <linux/backing-dev.h>
  28 #include <linux/freezer.h>
  29 #include <linux/kthread.h>
  30 #include <linux/crc32.h>
  31 #include <linux/pagevec.h>
  32 #include <linux/slab.h>
  33 #include "nilfs.h"
  34 #include "btnode.h"
  35 #include "page.h"
  36 #include "segment.h"
  37 #include "sufile.h"
  38 #include "cpfile.h"
  39 #include "ifile.h"
  40 #include "segbuf.h"
  41
  42
  43 /*
  44  * Segment constructor
  45  */
  46 #define SC_N_INODEVEC   16   /* Size of locally allocated inode vector */
  47
  48 #define SC_MAX_SEGDELTA 64   /*
  49                               * Upper limit of the number of segments
  50                               * appended in collection retry loop
  51                               */
  52
  53 /* Construction mode */
  54 enum {
  55         SC_LSEG_SR = 1, /* Make a logical segment having a super root */
  56         SC_LSEG_DSYNC,  /*
  57                          * Flush data blocks of a given file and make
  58                          * a logical segment without a super root.
  59                          */
  60         SC_FLUSH_FILE,  /*
  61                          * Flush data files, leads to segment writes without
  62                          * creating a checkpoint.
  63                          */
  64         SC_FLUSH_DAT,   /*
  65                          * Flush DAT file.  This also creates segments
  66                          * without a checkpoint.
  67                          */
  68 };
  69
  70 /* Stage numbers of dirty block collection */
  71 enum {
  72         NILFS_ST_INIT = 0,
  73         NILFS_ST_GC,            /* Collecting dirty blocks for GC */
  74         NILFS_ST_FILE,
  75         NILFS_ST_IFILE,
  76         NILFS_ST_CPFILE,
  77         NILFS_ST_SUFILE,
  78         NILFS_ST_DAT,
  79         NILFS_ST_SR,            /* Super root */
  80         NILFS_ST_DSYNC,         /* Data sync blocks */
  81         NILFS_ST_DONE,
  82 };
  83
  84 #define CREATE_TRACE_POINTS
  85 #include <trace/events/nilfs2.h>
  86
  87 /*
  88  * nilfs_sc_cstage_inc(), nilfs_sc_cstage_set(), nilfs_sc_cstage_get() are
  89  * wrapper functions of stage count (nilfs_sc_info->sc_stage.scnt). Users of
  90  * the variable must use them because transition of stage count must involve
  91  * trace events (trace_nilfs2_collection_stage_transition).
  92  *
  93  * nilfs_sc_cstage_get() isn't required for the above purpose because it doesn't
  94  * produce tracepoint events. It is provided just for making the intention
  95  * clear.
  96  */
  97 static inline void nilfs_sc_cstage_inc(struct nilfs_sc_info *sci)
  98 {
  99         sci->sc_stage.scnt++;
 100         trace_nilfs2_collection_stage_transition(sci);
 101 }
 102
 103 static inline void nilfs_sc_cstage_set(struct nilfs_sc_info *sci, int next_scnt)
 104 {
 105         sci->sc_stage.scnt = next_scnt;
 106         trace_nilfs2_collection_stage_transition(sci);
 107 }
 108
 109 static inline int nilfs_sc_cstage_get(struct nilfs_sc_info *sci)
 110 {
 111         return sci->sc_stage.scnt;
 112 }
 113
 114 /* State flags of collection */
 115 #define NILFS_CF_NODE           0x0001  /* Collecting node blocks */
 116 #define NILFS_CF_IFILE_STARTED  0x0002  /* IFILE stage has started */
 117 #define NILFS_CF_SUFREED        0x0004  /* segment usages has been freed */
 118 #define NILFS_CF_HISTORY_MASK   (NILFS_CF_IFILE_STARTED | NILFS_CF_SUFREED)
 119
 120 /* Operations depending on the construction mode and file type */
 121 struct nilfs_sc_operations {
 122         int (*collect_data)(struct nilfs_sc_info *, struct buffer_head *,
 123                             struct inode *);
 124         int (*collect_node)(struct nilfs_sc_info *, struct buffer_head *,
 125                             struct inode *);
 126         int (*collect_bmap)(struct nilfs_sc_info *, struct buffer_head *,
 127                             struct inode *);
 128         void (*write_data_binfo)(struct nilfs_sc_info *,
 129                                  struct nilfs_segsum_pointer *,
 130                                  union nilfs_binfo *);
 131         void (*write_node_binfo)(struct nilfs_sc_info *,
 132                                  struct nilfs_segsum_pointer *,
 133                                  union nilfs_binfo *);
 134 };
 135
 136 /*
 137  * Other definitions
 138  */
 139 static void nilfs_segctor_start_timer(struct nilfs_sc_info *);
 140 static void nilfs_segctor_do_flush(struct nilfs_sc_info *, int);
 141 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *);
 142 static void nilfs_dispose_list(struct the_nilfs *, struct list_head *, int);
 143
 144 #define nilfs_cnt32_gt(a, b)   \
 145         (typecheck(__u32, a) && typecheck(__u32, b) && \
 146          ((__s32)(b) - (__s32)(a) < 0))
 147 #define nilfs_cnt32_ge(a, b)   \
 148         (typecheck(__u32, a) && typecheck(__u32, b) && \
 149          ((__s32)(a) - (__s32)(b) >= 0))
 150 #define nilfs_cnt32_lt(a, b)  nilfs_cnt32_gt(b, a)
 151 #define nilfs_cnt32_le(a, b)  nilfs_cnt32_ge(b, a)
 152
 153 static int nilfs_prepare_segment_lock(struct super_block *sb,
 154                                       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
 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                 nilfs_msg(sb, KERN_WARNING, "journal info from a different FS");
 169                 save = current->journal_info;
 170         }
 171         if (!ti) {
 172                 ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
 173                 if (!ti)
 174                         return -ENOMEM;
 175                 ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
 176         } else {
 177                 ti->ti_flags = 0;
 178         }
 179         ti->ti_count = 0;
 180         ti->ti_save = save;
 181         ti->ti_magic = NILFS_TI_MAGIC;
 182         current->journal_info = ti;
 183         return 0;
 184 }
 185
 186 /**
 187  * nilfs_transaction_begin - start indivisible file operations.
 188  * @sb: super block
 189  * @ti: nilfs_transaction_info
 190  * @vacancy_check: flags for vacancy rate checks
 191  *
 192  * nilfs_transaction_begin() acquires a reader/writer semaphore, called
 193  * the segment semaphore, to make a segment construction and write tasks
 194  * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
 195  * The region enclosed by these two functions can be nested.  To avoid a
 196  * deadlock, the semaphore is only acquired or released in the outermost call.
 197  *
 198  * This function allocates a nilfs_transaction_info struct to keep context
 199  * information on it.  It is initialized and hooked onto the current task in
 200  * the outermost call.  If a pre-allocated struct is given to @ti, it is used
 201  * instead; otherwise a new struct is assigned from a slab.
 202  *
 203  * When @vacancy_check flag is set, this function will check the amount of
 204  * free space, and will wait for the GC to reclaim disk space if low capacity.
 205  *
 206  * Return Value: On success, 0 is returned. On error, one of the following
 207  * negative error code is returned.
 208  *
 209  * %-ENOMEM - Insufficient memory available.
 210  *
 211  * %-ENOSPC - No space left on device
 212  */
 213 int nilfs_transaction_begin(struct super_block *sb,
 214                             struct nilfs_transaction_info *ti,
 215                             int vacancy_check)
 216 {
 217         struct the_nilfs *nilfs;
 218         int ret = nilfs_prepare_segment_lock(sb, ti);
 219         struct nilfs_transaction_info *trace_ti;
 220
 221         if (unlikely(ret < 0))
 222                 return ret;
 223         if (ret > 0) {
 224                 trace_ti = current->journal_info;
 225
 226                 trace_nilfs2_transaction_transition(sb, trace_ti,
 227                                     trace_ti->ti_count, trace_ti->ti_flags,
 228                                     TRACE_NILFS2_TRANSACTION_BEGIN);
 229                 return 0;
 230         }
 231
 232         sb_start_intwrite(sb);
 233
 234         nilfs = sb->s_fs_info;
 235         down_read(&nilfs->ns_segctor_sem);
 236         if (vacancy_check && nilfs_near_disk_full(nilfs)) {
 237                 up_read(&nilfs->ns_segctor_sem);
 238                 ret = -ENOSPC;
 239                 goto failed;
 240         }
 241
 242         trace_ti = current->journal_info;
 243         trace_nilfs2_transaction_transition(sb, trace_ti, trace_ti->ti_count,
 244                                             trace_ti->ti_flags,
 245                                             TRACE_NILFS2_TRANSACTION_BEGIN);
 246         return 0;
 247
 248  failed:
 249         ti = current->journal_info;
 250         current->journal_info = ti->ti_save;
 251         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
 252                 kmem_cache_free(nilfs_transaction_cachep, ti);
 253         sb_end_intwrite(sb);
 254         return ret;
 255 }
 256
 257 /**
 258  * nilfs_transaction_commit - commit indivisible file operations.
 259  * @sb: super block
 260  *
 261  * nilfs_transaction_commit() releases the read semaphore which is
 262  * acquired by nilfs_transaction_begin(). This is only performed
 263  * in outermost call of this function.  If a commit flag is set,
 264  * nilfs_transaction_commit() sets a timer to start the segment
 265  * constructor.  If a sync flag is set, it starts construction
 266  * directly.
 267  */
 268 int nilfs_transaction_commit(struct super_block *sb)
 269 {
 270         struct nilfs_transaction_info *ti = current->journal_info;
 271         struct the_nilfs *nilfs = sb->s_fs_info;
 272         int err = 0;
 273
 274         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
 275         ti->ti_flags |= NILFS_TI_COMMIT;
 276         if (ti->ti_count > 0) {
 277                 ti->ti_count--;
 278                 trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
 279                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
 280                 return 0;
 281         }
 282         if (nilfs->ns_writer) {
 283                 struct nilfs_sc_info *sci = nilfs->ns_writer;
 284
 285                 if (ti->ti_flags & NILFS_TI_COMMIT)
 286                         nilfs_segctor_start_timer(sci);
 287                 if (atomic_read(&nilfs->ns_ndirtyblks) > sci->sc_watermark)
 288                         nilfs_segctor_do_flush(sci, 0);
 289         }
 290         up_read(&nilfs->ns_segctor_sem);
 291         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
 292                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
 293
 294         current->journal_info = ti->ti_save;
 295
 296         if (ti->ti_flags & NILFS_TI_SYNC)
 297                 err = nilfs_construct_segment(sb);
 298         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
 299                 kmem_cache_free(nilfs_transaction_cachep, ti);
 300         sb_end_intwrite(sb);
 301         return err;
 302 }
 303
 304 void nilfs_transaction_abort(struct super_block *sb)
 305 {
 306         struct nilfs_transaction_info *ti = current->journal_info;
 307         struct the_nilfs *nilfs = sb->s_fs_info;
 308
 309         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
 310         if (ti->ti_count > 0) {
 311                 ti->ti_count--;
 312                 trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
 313                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
 314                 return;
 315         }
 316         up_read(&nilfs->ns_segctor_sem);
 317
 318         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
 319                     ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
 320
 321         current->journal_info = ti->ti_save;
 322         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
 323                 kmem_cache_free(nilfs_transaction_cachep, ti);
 324         sb_end_intwrite(sb);
 325 }
 326
 327 void nilfs_relax_pressure_in_lock(struct super_block *sb)
 328 {
 329         struct the_nilfs *nilfs = sb->s_fs_info;
 330         struct nilfs_sc_info *sci = nilfs->ns_writer;
 331
 332         if (!sci || !sci->sc_flush_request)
 333                 return;
 334
 335         set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
 336         up_read(&nilfs->ns_segctor_sem);
 337
 338         down_write(&nilfs->ns_segctor_sem);
 339         if (sci->sc_flush_request &&
 340             test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
 341                 struct nilfs_transaction_info *ti = current->journal_info;
 342
 343                 ti->ti_flags |= NILFS_TI_WRITER;
 344                 nilfs_segctor_do_immediate_flush(sci);
 345                 ti->ti_flags &= ~NILFS_TI_WRITER;
 346         }
 347         downgrade_write(&nilfs->ns_segctor_sem);
 348 }
 349
 350 static void nilfs_transaction_lock(struct super_block *sb,
 351                                    struct nilfs_transaction_info *ti,
 352                                    int gcflag)
 353 {
 354         struct nilfs_transaction_info *cur_ti = current->journal_info;
 355         struct the_nilfs *nilfs = sb->s_fs_info;
 356         struct nilfs_sc_info *sci = nilfs->ns_writer;
 357
 358         WARN_ON(cur_ti);
 359         ti->ti_flags = NILFS_TI_WRITER;
 360         ti->ti_count = 0;
 361         ti->ti_save = cur_ti;
 362         ti->ti_magic = NILFS_TI_MAGIC;
 363         current->journal_info = ti;
 364
 365         for (;;) {
 366                 trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
 367                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_TRYLOCK);
 368
 369                 down_write(&nilfs->ns_segctor_sem);
 370                 if (!test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags))
 371                         break;
 372
 373                 nilfs_segctor_do_immediate_flush(sci);
 374
 375                 up_write(&nilfs->ns_segctor_sem);
 376                 cond_resched();
 377         }
 378         if (gcflag)
 379                 ti->ti_flags |= NILFS_TI_GC;
 380
 381         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
 382                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_LOCK);
 383 }
 384
 385 static void nilfs_transaction_unlock(struct super_block *sb)
 386 {
 387         struct nilfs_transaction_info *ti = current->journal_info;
 388         struct the_nilfs *nilfs = sb->s_fs_info;
 389
 390         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
 391         BUG_ON(ti->ti_count > 0);
 392
 393         up_write(&nilfs->ns_segctor_sem);
 394         current->journal_info = ti->ti_save;
 395
 396         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
 397                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_UNLOCK);
 398 }
 399
 400 static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
 401                                             struct nilfs_segsum_pointer *ssp,
 402                                             unsigned int bytes)
 403 {
 404         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
 405         unsigned int blocksize = sci->sc_super->s_blocksize;
 406         void *p;
 407
 408         if (unlikely(ssp->offset + bytes > blocksize)) {
 409                 ssp->offset = 0;
 410                 BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
 411                                                &segbuf->sb_segsum_buffers));
 412                 ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
 413         }
 414         p = ssp->bh->b_data + ssp->offset;
 415         ssp->offset += bytes;
 416         return p;
 417 }
 418
 419 /**
 420  * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
 421  * @sci: nilfs_sc_info
 422  */
 423 static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
 424 {
 425         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
 426         struct buffer_head *sumbh;
 427         unsigned int sumbytes;
 428         unsigned int flags = 0;
 429         int err;
 430
 431         if (nilfs_doing_gc())
 432                 flags = NILFS_SS_GC;
 433         err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime, sci->sc_cno);
 434         if (unlikely(err))
 435                 return err;
 436
 437         sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
 438         sumbytes = segbuf->sb_sum.sumbytes;
 439         sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
 440         sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
 441         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
 442         return 0;
 443 }
 444
 445 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
 446 {
 447         sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
 448         if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
 449                 return -E2BIG; /*
 450                                 * The current segment is filled up
 451                                 * (internal code)
 452                                 */
 453         sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
 454         return nilfs_segctor_reset_segment_buffer(sci);
 455 }
 456
 457 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
 458 {
 459         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
 460         int err;
 461
 462         if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
 463                 err = nilfs_segctor_feed_segment(sci);
 464                 if (err)
 465                         return err;
 466                 segbuf = sci->sc_curseg;
 467         }
 468         err = nilfs_segbuf_extend_payload(segbuf, &segbuf->sb_super_root);
 469         if (likely(!err))
 470                 segbuf->sb_sum.flags |= NILFS_SS_SR;
 471         return err;
 472 }
 473
 474 /*
 475  * Functions for making segment summary and payloads
 476  */
 477 static int nilfs_segctor_segsum_block_required(
 478         struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
 479         unsigned int binfo_size)
 480 {
 481         unsigned int blocksize = sci->sc_super->s_blocksize;
 482         /* Size of finfo and binfo is enough small against blocksize */
 483
 484         return ssp->offset + binfo_size +
 485                 (!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
 486                 blocksize;
 487 }
 488
 489 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
 490                                       struct inode *inode)
 491 {
 492         sci->sc_curseg->sb_sum.nfinfo++;
 493         sci->sc_binfo_ptr = sci->sc_finfo_ptr;
 494         nilfs_segctor_map_segsum_entry(
 495                 sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
 496
 497         if (NILFS_I(inode)->i_root &&
 498             !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
 499                 set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
 500         /* skip finfo */
 501 }
 502
 503 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
 504                                     struct inode *inode)
 505 {
 506         struct nilfs_finfo *finfo;
 507         struct nilfs_inode_info *ii;
 508         struct nilfs_segment_buffer *segbuf;
 509         __u64 cno;
 510
 511         if (sci->sc_blk_cnt == 0)
 512                 return;
 513
 514         ii = NILFS_I(inode);
 515
 516         if (test_bit(NILFS_I_GCINODE, &ii->i_state))
 517                 cno = ii->i_cno;
 518         else if (NILFS_ROOT_METADATA_FILE(inode->i_ino))
 519                 cno = 0;
 520         else
 521                 cno = sci->sc_cno;
 522
 523         finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
 524                                                  sizeof(*finfo));
 525         finfo->fi_ino = cpu_to_le64(inode->i_ino);
 526         finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
 527         finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
 528         finfo->fi_cno = cpu_to_le64(cno);
 529
 530         segbuf = sci->sc_curseg;
 531         segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
 532                 sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
 533         sci->sc_finfo_ptr = sci->sc_binfo_ptr;
 534         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
 535 }
 536
 537 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
 538                                         struct buffer_head *bh,
 539                                         struct inode *inode,
 540                                         unsigned int binfo_size)
 541 {
 542         struct nilfs_segment_buffer *segbuf;
 543         int required, err = 0;
 544
 545  retry:
 546         segbuf = sci->sc_curseg;
 547         required = nilfs_segctor_segsum_block_required(
 548                 sci, &sci->sc_binfo_ptr, binfo_size);
 549         if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
 550                 nilfs_segctor_end_finfo(sci, inode);
 551                 err = nilfs_segctor_feed_segment(sci);
 552                 if (err)
 553                         return err;
 554                 goto retry;
 555         }
 556         if (unlikely(required)) {
 557                 err = nilfs_segbuf_extend_segsum(segbuf);
 558                 if (unlikely(err))
 559                         goto failed;
 560         }
 561         if (sci->sc_blk_cnt == 0)
 562                 nilfs_segctor_begin_finfo(sci, inode);
 563
 564         nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
 565         /* Substitution to vblocknr is delayed until update_blocknr() */
 566         nilfs_segbuf_add_file_buffer(segbuf, bh);
 567         sci->sc_blk_cnt++;
 568  failed:
 569         return err;
 570 }
 571
 572 /*
 573  * Callback functions that enumerate, mark, and collect dirty blocks
 574  */
 575 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
 576                                    struct buffer_head *bh, struct inode *inode)
 577 {
 578         int err;
 579
 580         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
 581         if (err < 0)
 582                 return err;
 583
 584         err = nilfs_segctor_add_file_block(sci, bh, inode,
 585                                            sizeof(struct nilfs_binfo_v));
 586         if (!err)
 587                 sci->sc_datablk_cnt++;
 588         return err;
 589 }
 590
 591 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
 592                                    struct buffer_head *bh,
 593                                    struct inode *inode)
 594 {
 595         return nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
 596 }
 597
 598 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
 599                                    struct buffer_head *bh,
 600                                    struct inode *inode)
 601 {
 602         WARN_ON(!buffer_dirty(bh));
 603         return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
 604 }
 605
 606 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
 607                                         struct nilfs_segsum_pointer *ssp,
 608                                         union nilfs_binfo *binfo)
 609 {
 610         struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
 611                 sci, ssp, sizeof(*binfo_v));
 612         *binfo_v = binfo->bi_v;
 613 }
 614
 615 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
 616                                         struct nilfs_segsum_pointer *ssp,
 617                                         union nilfs_binfo *binfo)
 618 {
 619         __le64 *vblocknr = nilfs_segctor_map_segsum_entry(
 620                 sci, ssp, sizeof(*vblocknr));
 621         *vblocknr = binfo->bi_v.bi_vblocknr;
 622 }
 623
 624 static const struct nilfs_sc_operations nilfs_sc_file_ops = {
 625         .collect_data = nilfs_collect_file_data,
 626         .collect_node = nilfs_collect_file_node,
 627         .collect_bmap = nilfs_collect_file_bmap,
 628         .write_data_binfo = nilfs_write_file_data_binfo,
 629         .write_node_binfo = nilfs_write_file_node_binfo,
 630 };
 631
 632 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
 633                                   struct buffer_head *bh, struct inode *inode)
 634 {
 635         int err;
 636
 637         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
 638         if (err < 0)
 639                 return err;
 640
 641         err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
 642         if (!err)
 643                 sci->sc_datablk_cnt++;
 644         return err;
 645 }
 646
 647 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
 648                                   struct buffer_head *bh, struct inode *inode)
 649 {
 650         WARN_ON(!buffer_dirty(bh));
 651         return nilfs_segctor_add_file_block(sci, bh, inode,
 652                                             sizeof(struct nilfs_binfo_dat));
 653 }
 654
 655 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
 656                                        struct nilfs_segsum_pointer *ssp,
 657                                        union nilfs_binfo *binfo)
 658 {
 659         __le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
 660                                                           sizeof(*blkoff));
 661         *blkoff = binfo->bi_dat.bi_blkoff;
 662 }
 663
 664 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
 665                                        struct nilfs_segsum_pointer *ssp,
 666                                        union nilfs_binfo *binfo)
 667 {
 668         struct nilfs_binfo_dat *binfo_dat =
 669                 nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
 670         *binfo_dat = binfo->bi_dat;
 671 }
 672
 673 static const struct nilfs_sc_operations nilfs_sc_dat_ops = {
 674         .collect_data = nilfs_collect_dat_data,
 675         .collect_node = nilfs_collect_file_node,
 676         .collect_bmap = nilfs_collect_dat_bmap,
 677         .write_data_binfo = nilfs_write_dat_data_binfo,
 678         .write_node_binfo = nilfs_write_dat_node_binfo,
 679 };
 680
 681 static const struct nilfs_sc_operations nilfs_sc_dsync_ops = {
 682         .collect_data = nilfs_collect_file_data,
 683         .collect_node = NULL,
 684         .collect_bmap = NULL,
 685         .write_data_binfo = nilfs_write_file_data_binfo,
 686         .write_node_binfo = NULL,
 687 };
 688
 689 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
 690                                               struct list_head *listp,
 691                                               size_t nlimit,
 692                                               loff_t start, loff_t end)
 693 {
 694         struct address_space *mapping = inode->i_mapping;
 695         struct pagevec pvec;
 696         pgoff_t index = 0, last = ULONG_MAX;
 697         size_t ndirties = 0;
 698         int i;
 699
 700         if (unlikely(start != 0 || end != LLONG_MAX)) {
 701                 /*
 702                  * A valid range is given for sync-ing data pages. The
 703                  * range is rounded to per-page; extra dirty buffers
 704                  * may be included if blocksize < pagesize.
 705                  */
 706                 index = start >> PAGE_SHIFT;
 707                 last = end >> PAGE_SHIFT;
 708         }
 709         pagevec_init(&pvec, 0);
 710  repeat:
 711         if (unlikely(index > last) ||
 712             !pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
 713                                 min_t(pgoff_t, last - index,
 714                                       PAGEVEC_SIZE - 1) + 1))
 715                 return ndirties;
 716
 717         for (i = 0; i < pagevec_count(&pvec); i++) {
 718                 struct buffer_head *bh, *head;
 719                 struct page *page = pvec.pages[i];
 720
 721                 if (unlikely(page->index > last))
 722                         break;
 723
 724                 lock_page(page);
 725                 if (!page_has_buffers(page))
 726                         create_empty_buffers(page, 1 << inode->i_blkbits, 0);
 727                 unlock_page(page);
 728
 729                 bh = head = page_buffers(page);
 730                 do {
 731                         if (!buffer_dirty(bh) || buffer_async_write(bh))
 732                                 continue;
 733                         get_bh(bh);
 734                         list_add_tail(&bh->b_assoc_buffers, listp);
 735                         ndirties++;
 736                         if (unlikely(ndirties >= nlimit)) {
 737                                 pagevec_release(&pvec);
 738                                 cond_resched();
 739                                 return ndirties;
 740                         }
 741                 } while (bh = bh->b_this_page, bh != head);
 742         }
 743         pagevec_release(&pvec);
 744         cond_resched();
 745         goto repeat;
 746 }
 747
 748 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
 749                                             struct list_head *listp)
 750 {
 751         struct nilfs_inode_info *ii = NILFS_I(inode);
 752         struct address_space *mapping = &ii->i_btnode_cache;
 753         struct pagevec pvec;
 754         struct buffer_head *bh, *head;
 755         unsigned int i;
 756         pgoff_t index = 0;
 757
 758         pagevec_init(&pvec, 0);
 759
 760         while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
 761                                   PAGEVEC_SIZE)) {
 762                 for (i = 0; i < pagevec_count(&pvec); i++) {
 763                         bh = head = page_buffers(pvec.pages[i]);
 764                         do {
 765                                 if (buffer_dirty(bh) &&
 766                                                 !buffer_async_write(bh)) {
 767                                         get_bh(bh);
 768                                         list_add_tail(&bh->b_assoc_buffers,
 769                                                       listp);
 770                                 }
 771                                 bh = bh->b_this_page;
 772                         } while (bh != head);
 773                 }
 774                 pagevec_release(&pvec);
 775                 cond_resched();
 776         }
 777 }
 778
 779 static void nilfs_dispose_list(struct the_nilfs *nilfs,
 780                                struct list_head *head, int force)
 781 {
 782         struct nilfs_inode_info *ii, *n;
 783         struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
 784         unsigned int nv = 0;
 785
 786         while (!list_empty(head)) {
 787                 spin_lock(&nilfs->ns_inode_lock);
 788                 list_for_each_entry_safe(ii, n, head, i_dirty) {
 789                         list_del_init(&ii->i_dirty);
 790                         if (force) {
 791                                 if (unlikely(ii->i_bh)) {
 792                                         brelse(ii->i_bh);
 793                                         ii->i_bh = NULL;
 794                                 }
 795                         } else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
 796                                 set_bit(NILFS_I_QUEUED, &ii->i_state);
 797                                 list_add_tail(&ii->i_dirty,
 798                                               &nilfs->ns_dirty_files);
 799                                 continue;
 800                         }
 801                         ivec[nv++] = ii;
 802                         if (nv == SC_N_INODEVEC)
 803                                 break;
 804                 }
 805                 spin_unlock(&nilfs->ns_inode_lock);
 806
 807                 for (pii = ivec; nv > 0; pii++, nv--)
 808                         iput(&(*pii)->vfs_inode);
 809         }
 810 }
 811
 812 static void nilfs_iput_work_func(struct work_struct *work)
 813 {
 814         struct nilfs_sc_info *sci = container_of(work, struct nilfs_sc_info,
 815                                                  sc_iput_work);
 816         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
 817
 818         nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 0);
 819 }
 820
 821 static int nilfs_test_metadata_dirty(struct the_nilfs *nilfs,
 822                                      struct nilfs_root *root)
 823 {
 824         int ret = 0;
 825
 826         if (nilfs_mdt_fetch_dirty(root->ifile))
 827                 ret++;
 828         if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
 829                 ret++;
 830         if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
 831                 ret++;
 832         if ((ret || nilfs_doing_gc()) && nilfs_mdt_fetch_dirty(nilfs->ns_dat))
 833                 ret++;
 834         return ret;
 835 }
 836
 837 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
 838 {
 839         return list_empty(&sci->sc_dirty_files) &&
 840                 !test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
 841                 sci->sc_nfreesegs == 0 &&
 842                 (!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
 843 }
 844
 845 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
 846 {
 847         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
 848         int ret = 0;
 849
 850         if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
 851                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
 852
 853         spin_lock(&nilfs->ns_inode_lock);
 854         if (list_empty(&nilfs->ns_dirty_files) && nilfs_segctor_clean(sci))
 855                 ret++;
 856
 857         spin_unlock(&nilfs->ns_inode_lock);
 858         return ret;
 859 }
 860
 861 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
 862 {
 863         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
 864
 865         nilfs_mdt_clear_dirty(sci->sc_root->ifile);
 866         nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
 867         nilfs_mdt_clear_dirty(nilfs->ns_sufile);
 868         nilfs_mdt_clear_dirty(nilfs->ns_dat);
 869 }
 870
 871 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
 872 {
 873         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
 874         struct buffer_head *bh_cp;
 875         struct nilfs_checkpoint *raw_cp;
 876         int err;
 877
 878         /* XXX: this interface will be changed */
 879         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
 880                                           &raw_cp, &bh_cp);
 881         if (likely(!err)) {
 882                 /*
 883                  * The following code is duplicated with cpfile.  But, it is
 884                  * needed to collect the checkpoint even if it was not newly
 885                  * created.
 886                  */
 887                 mark_buffer_dirty(bh_cp);
 888                 nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
 889                 nilfs_cpfile_put_checkpoint(
 890                         nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
 891         } else
 892                 WARN_ON(err == -EINVAL || err == -ENOENT);
 893
 894         return err;
 895 }
 896
 897 static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
 898 {
 899         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
 900         struct buffer_head *bh_cp;
 901         struct nilfs_checkpoint *raw_cp;
 902         int err;
 903
 904         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
 905                                           &raw_cp, &bh_cp);
 906         if (unlikely(err)) {
 907                 WARN_ON(err == -EINVAL || err == -ENOENT);
 908                 goto failed_ibh;
 909         }
 910         raw_cp->cp_snapshot_list.ssl_next = 0;
 911         raw_cp->cp_snapshot_list.ssl_prev = 0;
 912         raw_cp->cp_inodes_count =
 913                 cpu_to_le64(atomic64_read(&sci->sc_root->inodes_count));
 914         raw_cp->cp_blocks_count =
 915                 cpu_to_le64(atomic64_read(&sci->sc_root->blocks_count));
 916         raw_cp->cp_nblk_inc =
 917                 cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
 918         raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
 919         raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
 920
 921         if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
 922                 nilfs_checkpoint_clear_minor(raw_cp);
 923         else
 924                 nilfs_checkpoint_set_minor(raw_cp);
 925
 926         nilfs_write_inode_common(sci->sc_root->ifile,
 927                                  &raw_cp->cp_ifile_inode, 1);
 928         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
 929         return 0;
 930
 931  failed_ibh:
 932         return err;
 933 }
 934
 935 static void nilfs_fill_in_file_bmap(struct inode *ifile,
 936                                     struct nilfs_inode_info *ii)
 937
 938 {
 939         struct buffer_head *ibh;
 940         struct nilfs_inode *raw_inode;
 941
 942         if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
 943                 ibh = ii->i_bh;
 944                 BUG_ON(!ibh);
 945                 raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
 946                                                   ibh);
 947                 nilfs_bmap_write(ii->i_bmap, raw_inode);
 948                 nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
 949         }
 950 }
 951
 952 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci)
 953 {
 954         struct nilfs_inode_info *ii;
 955
 956         list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
 957                 nilfs_fill_in_file_bmap(sci->sc_root->ifile, ii);
 958                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
 959         }
 960 }
 961
 962 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
 963                                              struct the_nilfs *nilfs)
 964 {
 965         struct buffer_head *bh_sr;
 966         struct nilfs_super_root *raw_sr;
 967         unsigned int isz, srsz;
 968
 969         bh_sr = NILFS_LAST_SEGBUF(&sci->sc_segbufs)->sb_super_root;
 970         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 971         isz = nilfs->ns_inode_size;
 972         srsz = NILFS_SR_BYTES(isz);
 973
 974         raw_sr->sr_bytes = cpu_to_le16(srsz);
 975         raw_sr->sr_nongc_ctime
 976                 = cpu_to_le64(nilfs_doing_gc() ?
 977                               nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
 978         raw_sr->sr_flags = 0;
 979
 980         nilfs_write_inode_common(nilfs->ns_dat, (void *)raw_sr +
 981                                  NILFS_SR_DAT_OFFSET(isz), 1);
 982         nilfs_write_inode_common(nilfs->ns_cpfile, (void *)raw_sr +
 983                                  NILFS_SR_CPFILE_OFFSET(isz), 1);
 984         nilfs_write_inode_common(nilfs->ns_sufile, (void *)raw_sr +
 985                                  NILFS_SR_SUFILE_OFFSET(isz), 1);
 986         memset((void *)raw_sr + srsz, 0, nilfs->ns_blocksize - srsz);
 987 }
 988
 989 static void nilfs_redirty_inodes(struct list_head *head)
 990 {
 991         struct nilfs_inode_info *ii;
 992
 993         list_for_each_entry(ii, head, i_dirty) {
 994                 if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
 995                         clear_bit(NILFS_I_COLLECTED, &ii->i_state);
 996         }
 997 }
 998
 999 static void nilfs_drop_collected_inodes(struct list_head *head)
1000 {
1001         struct nilfs_inode_info *ii;
1002
1003         list_for_each_entry(ii, head, i_dirty) {
1004                 if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
1005                         continue;
1006
1007                 clear_bit(NILFS_I_INODE_SYNC, &ii->i_state);
1008                 set_bit(NILFS_I_UPDATED, &ii->i_state);
1009         }
1010 }
1011
1012 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
1013                                        struct inode *inode,
1014                                        struct list_head *listp,
1015                                        int (*collect)(struct nilfs_sc_info *,
1016                                                       struct buffer_head *,
1017                                                       struct inode *))
1018 {
1019         struct buffer_head *bh, *n;
1020         int err = 0;
1021
1022         if (collect) {
1023                 list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
1024                         list_del_init(&bh->b_assoc_buffers);
1025                         err = collect(sci, bh, inode);
1026                         brelse(bh);
1027                         if (unlikely(err))
1028                                 goto dispose_buffers;
1029                 }
1030                 return 0;
1031         }
1032
1033  dispose_buffers:
1034         while (!list_empty(listp)) {
1035                 bh = list_first_entry(listp, struct buffer_head,
1036                                       b_assoc_buffers);
1037                 list_del_init(&bh->b_assoc_buffers);
1038                 brelse(bh);
1039         }
1040         return err;
1041 }
1042
1043 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
1044 {
1045         /* Remaining number of blocks within segment buffer */
1046         return sci->sc_segbuf_nblocks -
1047                 (sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
1048 }
1049
1050 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
1051                                    struct inode *inode,
1052                                    const struct nilfs_sc_operations *sc_ops)
1053 {
1054         LIST_HEAD(data_buffers);
1055         LIST_HEAD(node_buffers);
1056         int err;
1057
1058         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1059                 size_t n, rest = nilfs_segctor_buffer_rest(sci);
1060
1061                 n = nilfs_lookup_dirty_data_buffers(
1062                         inode, &data_buffers, rest + 1, 0, LLONG_MAX);
1063                 if (n > rest) {
1064                         err = nilfs_segctor_apply_buffers(
1065                                 sci, inode, &data_buffers,
1066                                 sc_ops->collect_data);
1067                         BUG_ON(!err); /* always receive -E2BIG or true error */
1068                         goto break_or_fail;
1069                 }
1070         }
1071         nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1072
1073         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1074                 err = nilfs_segctor_apply_buffers(
1075                         sci, inode, &data_buffers, sc_ops->collect_data);
1076                 if (unlikely(err)) {
1077                         /* dispose node list */
1078                         nilfs_segctor_apply_buffers(
1079                                 sci, inode, &node_buffers, NULL);
1080                         goto break_or_fail;
1081                 }
1082                 sci->sc_stage.flags |= NILFS_CF_NODE;
1083         }
1084         /* Collect node */
1085         err = nilfs_segctor_apply_buffers(
1086                 sci, inode, &node_buffers, sc_ops->collect_node);
1087         if (unlikely(err))
1088                 goto break_or_fail;
1089
1090         nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1091         err = nilfs_segctor_apply_buffers(
1092                 sci, inode, &node_buffers, sc_ops->collect_bmap);
1093         if (unlikely(err))
1094                 goto break_or_fail;
1095
1096         nilfs_segctor_end_finfo(sci, inode);
1097         sci->sc_stage.flags &= ~NILFS_CF_NODE;
1098
1099  break_or_fail:
1100         return err;
1101 }
1102
1103 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1104                                          struct inode *inode)
1105 {
1106         LIST_HEAD(data_buffers);
1107         size_t n, rest = nilfs_segctor_buffer_rest(sci);
1108         int err;
1109
1110         n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1111                                             sci->sc_dsync_start,
1112                                             sci->sc_dsync_end);
1113
1114         err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1115                                           nilfs_collect_file_data);
1116         if (!err) {
1117                 nilfs_segctor_end_finfo(sci, inode);
1118                 BUG_ON(n > rest);
1119                 /* always receive -E2BIG or true error if n > rest */
1120         }
1121         return err;
1122 }
1123
1124 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1125 {
1126         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1127         struct list_head *head;
1128         struct nilfs_inode_info *ii;
1129         size_t ndone;
1130         int err = 0;
1131
1132         switch (nilfs_sc_cstage_get(sci)) {
1133         case NILFS_ST_INIT:
1134                 /* Pre-processes */
1135                 sci->sc_stage.flags = 0;
1136
1137                 if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1138                         sci->sc_nblk_inc = 0;
1139                         sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1140                         if (mode == SC_LSEG_DSYNC) {
1141                                 nilfs_sc_cstage_set(sci, NILFS_ST_DSYNC);
1142                                 goto dsync_mode;
1143                         }
1144                 }
1145
1146                 sci->sc_stage.dirty_file_ptr = NULL;
1147                 sci->sc_stage.gc_inode_ptr = NULL;
1148                 if (mode == SC_FLUSH_DAT) {
1149                         nilfs_sc_cstage_set(sci, NILFS_ST_DAT);
1150                         goto dat_stage;
1151                 }
1152                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1153         case NILFS_ST_GC:
1154                 if (nilfs_doing_gc()) {
1155                         head = &sci->sc_gc_inodes;
1156                         ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1157                                                 head, i_dirty);
1158                         list_for_each_entry_continue(ii, head, i_dirty) {
1159                                 err = nilfs_segctor_scan_file(
1160                                         sci, &ii->vfs_inode,
1161                                         &nilfs_sc_file_ops);
1162                                 if (unlikely(err)) {
1163                                         sci->sc_stage.gc_inode_ptr = list_entry(
1164                                                 ii->i_dirty.prev,
1165                                                 struct nilfs_inode_info,
1166                                                 i_dirty);
1167                                         goto break_or_fail;
1168                                 }
1169                                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
1170                         }
1171                         sci->sc_stage.gc_inode_ptr = NULL;
1172                 }
1173                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1174         case NILFS_ST_FILE:
1175                 head = &sci->sc_dirty_files;
1176                 ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1177                                         i_dirty);
1178                 list_for_each_entry_continue(ii, head, i_dirty) {
1179                         clear_bit(NILFS_I_DIRTY, &ii->i_state);
1180
1181                         err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1182                                                       &nilfs_sc_file_ops);
1183                         if (unlikely(err)) {
1184                                 sci->sc_stage.dirty_file_ptr =
1185                                         list_entry(ii->i_dirty.prev,
1186                                                    struct nilfs_inode_info,
1187                                                    i_dirty);
1188                                 goto break_or_fail;
1189                         }
1190                         /* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1191                         /* XXX: required ? */
1192                 }
1193                 sci->sc_stage.dirty_file_ptr = NULL;
1194                 if (mode == SC_FLUSH_FILE) {
1195                         nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1196                         return 0;
1197                 }
1198                 nilfs_sc_cstage_inc(sci);
1199                 sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1200                 /* Fall through */
1201         case NILFS_ST_IFILE:
1202                 err = nilfs_segctor_scan_file(sci, sci->sc_root->ifile,
1203                                               &nilfs_sc_file_ops);
1204                 if (unlikely(err))
1205                         break;
1206                 nilfs_sc_cstage_inc(sci);
1207                 /* Creating a checkpoint */
1208                 err = nilfs_segctor_create_checkpoint(sci);
1209                 if (unlikely(err))
1210                         break;
1211                 /* Fall through */
1212         case NILFS_ST_CPFILE:
1213                 err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1214                                               &nilfs_sc_file_ops);
1215                 if (unlikely(err))
1216                         break;
1217                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1218         case NILFS_ST_SUFILE:
1219                 err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1220                                          sci->sc_nfreesegs, &ndone);
1221                 if (unlikely(err)) {
1222                         nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1223                                                   sci->sc_freesegs, ndone,
1224                                                   NULL);
1225                         break;
1226                 }
1227                 sci->sc_stage.flags |= NILFS_CF_SUFREED;
1228
1229                 err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1230                                               &nilfs_sc_file_ops);
1231                 if (unlikely(err))
1232                         break;
1233                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1234         case NILFS_ST_DAT:
1235  dat_stage:
1236                 err = nilfs_segctor_scan_file(sci, nilfs->ns_dat,
1237                                               &nilfs_sc_dat_ops);
1238                 if (unlikely(err))
1239                         break;
1240                 if (mode == SC_FLUSH_DAT) {
1241                         nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1242                         return 0;
1243                 }
1244                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1245         case NILFS_ST_SR:
1246                 if (mode == SC_LSEG_SR) {
1247                         /* Appending a super root */
1248                         err = nilfs_segctor_add_super_root(sci);
1249                         if (unlikely(err))
1250                                 break;
1251                 }
1252                 /* End of a logical segment */
1253                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1254                 nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1255                 return 0;
1256         case NILFS_ST_DSYNC:
1257  dsync_mode:
1258                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1259                 ii = sci->sc_dsync_inode;
1260                 if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1261                         break;
1262
1263                 err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1264                 if (unlikely(err))
1265                         break;
1266                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1267                 nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1268                 return 0;
1269         case NILFS_ST_DONE:
1270                 return 0;
1271         default:
1272                 BUG();
1273         }
1274
1275  break_or_fail:
1276         return err;
1277 }
1278
1279 /**
1280  * nilfs_segctor_begin_construction - setup segment buffer to make a new log
1281  * @sci: nilfs_sc_info
1282  * @nilfs: nilfs object
1283  */
1284 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1285                                             struct the_nilfs *nilfs)
1286 {
1287         struct nilfs_segment_buffer *segbuf, *prev;
1288         __u64 nextnum;
1289         int err, alloc = 0;
1290
1291         segbuf = nilfs_segbuf_new(sci->sc_super);
1292         if (unlikely(!segbuf))
1293                 return -ENOMEM;
1294
1295         if (list_empty(&sci->sc_write_logs)) {
1296                 nilfs_segbuf_map(segbuf, nilfs->ns_segnum,
1297                                  nilfs->ns_pseg_offset, nilfs);
1298                 if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1299                         nilfs_shift_to_next_segment(nilfs);
1300                         nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1301                 }
1302
1303                 segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1304                 nextnum = nilfs->ns_nextnum;
1305
1306                 if (nilfs->ns_segnum == nilfs->ns_nextnum)
1307                         /* Start from the head of a new full segment */
1308                         alloc++;
1309         } else {
1310                 /* Continue logs */
1311                 prev = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1312                 nilfs_segbuf_map_cont(segbuf, prev);
1313                 segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq;
1314                 nextnum = prev->sb_nextnum;
1315
1316                 if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1317                         nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1318                         segbuf->sb_sum.seg_seq++;
1319                         alloc++;
1320                 }
1321         }
1322
1323         err = nilfs_sufile_mark_dirty(nilfs->ns_sufile, segbuf->sb_segnum);
1324         if (err)
1325                 goto failed;
1326
1327         if (alloc) {
1328                 err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1329                 if (err)
1330                         goto failed;
1331         }
1332         nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1333
1334         BUG_ON(!list_empty(&sci->sc_segbufs));
1335         list_add_tail(&segbuf->sb_list, &sci->sc_segbufs);
1336         sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1337         return 0;
1338
1339  failed:
1340         nilfs_segbuf_free(segbuf);
1341         return err;
1342 }
1343
1344 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1345                                          struct the_nilfs *nilfs, int nadd)
1346 {
1347         struct nilfs_segment_buffer *segbuf, *prev;
1348         struct inode *sufile = nilfs->ns_sufile;
1349         __u64 nextnextnum;
1350         LIST_HEAD(list);
1351         int err, ret, i;
1352
1353         prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1354         /*
1355          * Since the segment specified with nextnum might be allocated during
1356          * the previous construction, the buffer including its segusage may
1357          * not be dirty.  The following call ensures that the buffer is dirty
1358          * and will pin the buffer on memory until the sufile is written.
1359          */
1360         err = nilfs_sufile_mark_dirty(sufile, prev->sb_nextnum);
1361         if (unlikely(err))
1362                 return err;
1363
1364         for (i = 0; i < nadd; i++) {
1365                 /* extend segment info */
1366                 err = -ENOMEM;
1367                 segbuf = nilfs_segbuf_new(sci->sc_super);
1368                 if (unlikely(!segbuf))
1369                         goto failed;
1370
1371                 /* map this buffer to region of segment on-disk */
1372                 nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1373                 sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1374
1375                 /* allocate the next next full segment */
1376                 err = nilfs_sufile_alloc(sufile, &nextnextnum);
1377                 if (unlikely(err))
1378                         goto failed_segbuf;
1379
1380                 segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1381                 nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1382
1383                 list_add_tail(&segbuf->sb_list, &list);
1384                 prev = segbuf;
1385         }
1386         list_splice_tail(&list, &sci->sc_segbufs);
1387         return 0;
1388
1389  failed_segbuf:
1390         nilfs_segbuf_free(segbuf);
1391  failed:
1392         list_for_each_entry(segbuf, &list, sb_list) {
1393                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1394                 WARN_ON(ret); /* never fails */
1395         }
1396         nilfs_destroy_logs(&list);
1397         return err;
1398 }
1399
1400 static void nilfs_free_incomplete_logs(struct list_head *logs,
1401                                        struct the_nilfs *nilfs)
1402 {
1403         struct nilfs_segment_buffer *segbuf, *prev;
1404         struct inode *sufile = nilfs->ns_sufile;
1405         int ret;
1406
1407         segbuf = NILFS_FIRST_SEGBUF(logs);
1408         if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1409                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1410                 WARN_ON(ret); /* never fails */
1411         }
1412         if (atomic_read(&segbuf->sb_err)) {
1413                 /* Case 1: The first segment failed */
1414                 if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1415                         /*
1416                          * Case 1a:  Partial segment appended into an existing
1417                          * segment
1418                          */
1419                         nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1420                                                 segbuf->sb_fseg_end);
1421                 else /* Case 1b:  New full segment */
1422                         set_nilfs_discontinued(nilfs);
1423         }
1424
1425         prev = segbuf;
1426         list_for_each_entry_continue(segbuf, logs, sb_list) {
1427                 if (prev->sb_nextnum != segbuf->sb_nextnum) {
1428                         ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1429                         WARN_ON(ret); /* never fails */
1430                 }
1431                 if (atomic_read(&segbuf->sb_err) &&
1432                     segbuf->sb_segnum != nilfs->ns_nextnum)
1433                         /* Case 2: extended segment (!= next) failed */
1434                         nilfs_sufile_set_error(sufile, segbuf->sb_segnum);
1435                 prev = segbuf;
1436         }
1437 }
1438
1439 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1440                                           struct inode *sufile)
1441 {
1442         struct nilfs_segment_buffer *segbuf;
1443         unsigned long live_blocks;
1444         int ret;
1445
1446         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1447                 live_blocks = segbuf->sb_sum.nblocks +
1448                         (segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1449                 ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1450                                                      live_blocks,
1451                                                      sci->sc_seg_ctime);
1452                 WARN_ON(ret); /* always succeed because the segusage is dirty */
1453         }
1454 }
1455
1456 static void nilfs_cancel_segusage(struct list_head *logs, struct inode *sufile)
1457 {
1458         struct nilfs_segment_buffer *segbuf;
1459         int ret;
1460
1461         segbuf = NILFS_FIRST_SEGBUF(logs);
1462         ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1463                                              segbuf->sb_pseg_start -
1464                                              segbuf->sb_fseg_start, 0);
1465         WARN_ON(ret); /* always succeed because the segusage is dirty */
1466
1467         list_for_each_entry_continue(segbuf, logs, sb_list) {
1468                 ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1469                                                      0, 0);
1470                 WARN_ON(ret); /* always succeed */
1471         }
1472 }
1473
1474 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1475                                             struct nilfs_segment_buffer *last,
1476                                             struct inode *sufile)
1477 {
1478         struct nilfs_segment_buffer *segbuf = last;
1479         int ret;
1480
1481         list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1482                 sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1483                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1484                 WARN_ON(ret);
1485         }
1486         nilfs_truncate_logs(&sci->sc_segbufs, last);
1487 }
1488
1489
1490 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1491                                  struct the_nilfs *nilfs, int mode)
1492 {
1493         struct nilfs_cstage prev_stage = sci->sc_stage;
1494         int err, nadd = 1;
1495
1496         /* Collection retry loop */
1497         for (;;) {
1498                 sci->sc_nblk_this_inc = 0;
1499                 sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1500
1501                 err = nilfs_segctor_reset_segment_buffer(sci);
1502                 if (unlikely(err))
1503                         goto failed;
1504
1505                 err = nilfs_segctor_collect_blocks(sci, mode);
1506                 sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1507                 if (!err)
1508                         break;
1509
1510                 if (unlikely(err != -E2BIG))
1511                         goto failed;
1512
1513                 /* The current segment is filled up */
1514                 if (mode != SC_LSEG_SR ||
1515                     nilfs_sc_cstage_get(sci) < NILFS_ST_CPFILE)
1516                         break;
1517
1518                 nilfs_clear_logs(&sci->sc_segbufs);
1519
1520                 if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1521                         err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1522                                                         sci->sc_freesegs,
1523                                                         sci->sc_nfreesegs,
1524                                                         NULL);
1525                         WARN_ON(err); /* do not happen */
1526                         sci->sc_stage.flags &= ~NILFS_CF_SUFREED;
1527                 }
1528
1529                 err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1530                 if (unlikely(err))
1531                         return err;
1532
1533                 nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1534                 sci->sc_stage = prev_stage;
1535         }
1536         nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1537         return 0;
1538
1539  failed:
1540         return err;
1541 }
1542
1543 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1544                                       struct buffer_head *new_bh)
1545 {
1546         BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1547
1548         list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1549         /* The caller must release old_bh */
1550 }
1551
1552 static int
1553 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1554                                      struct nilfs_segment_buffer *segbuf,
1555                                      int mode)
1556 {
1557         struct inode *inode = NULL;
1558         sector_t blocknr;
1559         unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1560         unsigned long nblocks = 0, ndatablk = 0;
1561         const struct nilfs_sc_operations *sc_op = NULL;
1562         struct nilfs_segsum_pointer ssp;
1563         struct nilfs_finfo *finfo = NULL;
1564         union nilfs_binfo binfo;
1565         struct buffer_head *bh, *bh_org;
1566         ino_t ino = 0;
1567         int err = 0;
1568
1569         if (!nfinfo)
1570                 goto out;
1571
1572         blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1573         ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1574         ssp.offset = sizeof(struct nilfs_segment_summary);
1575
1576         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1577                 if (bh == segbuf->sb_super_root)
1578                         break;
1579                 if (!finfo) {
1580                         finfo = nilfs_segctor_map_segsum_entry(
1581                                 sci, &ssp, sizeof(*finfo));
1582                         ino = le64_to_cpu(finfo->fi_ino);
1583                         nblocks = le32_to_cpu(finfo->fi_nblocks);
1584                         ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1585
1586                         inode = bh->b_page->mapping->host;
1587
1588                         if (mode == SC_LSEG_DSYNC)
1589                                 sc_op = &nilfs_sc_dsync_ops;
1590                         else if (ino == NILFS_DAT_INO)
1591                                 sc_op = &nilfs_sc_dat_ops;
1592                         else /* file blocks */
1593                                 sc_op = &nilfs_sc_file_ops;
1594                 }
1595                 bh_org = bh;
1596                 get_bh(bh_org);
1597                 err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1598                                         &binfo);
1599                 if (bh != bh_org)
1600                         nilfs_list_replace_buffer(bh_org, bh);
1601                 brelse(bh_org);
1602                 if (unlikely(err))
1603                         goto failed_bmap;
1604
1605                 if (ndatablk > 0)
1606                         sc_op->write_data_binfo(sci, &ssp, &binfo);
1607                 else
1608                         sc_op->write_node_binfo(sci, &ssp, &binfo);
1609
1610                 blocknr++;
1611                 if (--nblocks == 0) {
1612                         finfo = NULL;
1613                         if (--nfinfo == 0)
1614                                 break;
1615                 } else if (ndatablk > 0)
1616                         ndatablk--;
1617         }
1618  out:
1619         return 0;
1620
1621  failed_bmap:
1622         return err;
1623 }
1624
1625 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1626 {
1627         struct nilfs_segment_buffer *segbuf;
1628         int err;
1629
1630         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1631                 err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1632                 if (unlikely(err))
1633                         return err;
1634                 nilfs_segbuf_fill_in_segsum(segbuf);
1635         }
1636         return 0;
1637 }
1638
1639 static void nilfs_begin_page_io(struct page *page)
1640 {
1641         if (!page || PageWriteback(page))
1642                 /*
1643                  * For split b-tree node pages, this function may be called
1644                  * twice.  We ignore the 2nd or later calls by this check.
1645                  */
1646                 return;
1647
1648         lock_page(page);
1649         clear_page_dirty_for_io(page);
1650         set_page_writeback(page);
1651         unlock_page(page);
1652 }
1653
1654 static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
1655 {
1656         struct nilfs_segment_buffer *segbuf;
1657         struct page *bd_page = NULL, *fs_page = NULL;
1658
1659         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1660                 struct buffer_head *bh;
1661
1662                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1663                                     b_assoc_buffers) {
1664                         if (bh->b_page != bd_page) {
1665                                 if (bd_page) {
1666                                         lock_page(bd_page);
1667                                         clear_page_dirty_for_io(bd_page);
1668                                         set_page_writeback(bd_page);
1669                                         unlock_page(bd_page);
1670                                 }
1671                                 bd_page = bh->b_page;
1672                         }
1673                 }
1674
1675                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1676                                     b_assoc_buffers) {
1677                         set_buffer_async_write(bh);
1678                         if (bh == segbuf->sb_super_root) {
1679                                 if (bh->b_page != bd_page) {
1680                                         lock_page(bd_page);
1681                                         clear_page_dirty_for_io(bd_page);
1682                                         set_page_writeback(bd_page);
1683                                         unlock_page(bd_page);
1684                                         bd_page = bh->b_page;
1685                                 }
1686                                 break;
1687                         }
1688                         if (bh->b_page != fs_page) {
1689                                 nilfs_begin_page_io(fs_page);
1690                                 fs_page = bh->b_page;
1691                         }
1692                 }
1693         }
1694         if (bd_page) {
1695                 lock_page(bd_page);
1696                 clear_page_dirty_for_io(bd_page);
1697                 set_page_writeback(bd_page);
1698                 unlock_page(bd_page);
1699         }
1700         nilfs_begin_page_io(fs_page);
1701 }
1702
1703 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1704                                struct the_nilfs *nilfs)
1705 {
1706         int ret;
1707
1708         ret = nilfs_write_logs(&sci->sc_segbufs, nilfs);
1709         list_splice_tail_init(&sci->sc_segbufs, &sci->sc_write_logs);
1710         return ret;
1711 }
1712
1713 static void nilfs_end_page_io(struct page *page, int err)
1714 {
1715         if (!page)
1716                 return;
1717
1718         if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1719                 /*
1720                  * For b-tree node pages, this function may be called twice
1721                  * or more because they might be split in a segment.
1722                  */
1723                 if (PageDirty(page)) {
1724                         /*
1725                          * For pages holding split b-tree node buffers, dirty
1726                          * flag on the buffers may be cleared discretely.
1727                          * In that case, the page is once redirtied for
1728                          * remaining buffers, and it must be cancelled if
1729                          * all the buffers get cleaned later.
1730                          */
1731                         lock_page(page);
1732                         if (nilfs_page_buffers_clean(page))
1733                                 __nilfs_clear_page_dirty(page);
1734                         unlock_page(page);
1735                 }
1736                 return;
1737         }
1738
1739         if (!err) {
1740                 if (!nilfs_page_buffers_clean(page))
1741                         __set_page_dirty_nobuffers(page);
1742                 ClearPageError(page);
1743         } else {
1744                 __set_page_dirty_nobuffers(page);
1745                 SetPageError(page);
1746         }
1747
1748         end_page_writeback(page);
1749 }
1750
1751 static void nilfs_abort_logs(struct list_head *logs, int err)
1752 {
1753         struct nilfs_segment_buffer *segbuf;
1754         struct page *bd_page = NULL, *fs_page = NULL;
1755         struct buffer_head *bh;
1756
1757         if (list_empty(logs))
1758                 return;
1759
1760         list_for_each_entry(segbuf, logs, sb_list) {
1761                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1762                                     b_assoc_buffers) {
1763                         if (bh->b_page != bd_page) {
1764                                 if (bd_page)
1765                                         end_page_writeback(bd_page);
1766                                 bd_page = bh->b_page;
1767                         }
1768                 }
1769
1770                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1771                                     b_assoc_buffers) {
1772                         clear_buffer_async_write(bh);
1773                         if (bh == segbuf->sb_super_root) {
1774                                 if (bh->b_page != bd_page) {
1775                                         end_page_writeback(bd_page);
1776                                         bd_page = bh->b_page;
1777                                 }
1778                                 break;
1779                         }
1780                         if (bh->b_page != fs_page) {
1781                                 nilfs_end_page_io(fs_page, err);
1782                                 fs_page = bh->b_page;
1783                         }
1784                 }
1785         }
1786         if (bd_page)
1787                 end_page_writeback(bd_page);
1788
1789         nilfs_end_page_io(fs_page, err);
1790 }
1791
1792 static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
1793                                              struct the_nilfs *nilfs, int err)
1794 {
1795         LIST_HEAD(logs);
1796         int ret;
1797
1798         list_splice_tail_init(&sci->sc_write_logs, &logs);
1799         ret = nilfs_wait_on_logs(&logs);
1800         nilfs_abort_logs(&logs, ret ? : err);
1801
1802         list_splice_tail_init(&sci->sc_segbufs, &logs);
1803         nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
1804         nilfs_free_incomplete_logs(&logs, nilfs);
1805
1806         if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1807                 ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1808                                                 sci->sc_freesegs,
1809                                                 sci->sc_nfreesegs,
1810                                                 NULL);
1811                 WARN_ON(ret); /* do not happen */
1812         }
1813
1814         nilfs_destroy_logs(&logs);
1815 }
1816
1817 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1818                                    struct nilfs_segment_buffer *segbuf)
1819 {
1820         nilfs->ns_segnum = segbuf->sb_segnum;
1821         nilfs->ns_nextnum = segbuf->sb_nextnum;
1822         nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1823                 + segbuf->sb_sum.nblocks;
1824         nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1825         nilfs->ns_ctime = segbuf->sb_sum.ctime;
1826 }
1827
1828 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1829 {
1830         struct nilfs_segment_buffer *segbuf;
1831         struct page *bd_page = NULL, *fs_page = NULL;
1832         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1833         int update_sr = false;
1834
1835         list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
1836                 struct buffer_head *bh;
1837
1838                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1839                                     b_assoc_buffers) {
1840                         set_buffer_uptodate(bh);
1841                         clear_buffer_dirty(bh);
1842                         if (bh->b_page != bd_page) {
1843                                 if (bd_page)
1844                                         end_page_writeback(bd_page);
1845                                 bd_page = bh->b_page;
1846                         }
1847                 }
1848                 /*
1849                  * We assume that the buffers which belong to the same page
1850                  * continue over the buffer list.
1851                  * Under this assumption, the last BHs of pages is
1852                  * identifiable by the discontinuity of bh->b_page
1853                  * (page != fs_page).
1854                  *
1855                  * For B-tree node blocks, however, this assumption is not
1856                  * guaranteed.  The cleanup code of B-tree node pages needs
1857                  * special care.
1858                  */
1859                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1860                                     b_assoc_buffers) {
1861                         const unsigned long set_bits = BIT(BH_Uptodate);
1862                         const unsigned long clear_bits =
1863                                 (BIT(BH_Dirty) | BIT(BH_Async_Write) |
1864                                  BIT(BH_Delay) | BIT(BH_NILFS_Volatile) |
1865                                  BIT(BH_NILFS_Redirected));
1866
1867                         set_mask_bits(&bh->b_state, clear_bits, set_bits);
1868                         if (bh == segbuf->sb_super_root) {
1869                                 if (bh->b_page != bd_page) {
1870                                         end_page_writeback(bd_page);
1871                                         bd_page = bh->b_page;
1872                                 }
1873                                 update_sr = true;
1874                                 break;
1875                         }
1876                         if (bh->b_page != fs_page) {
1877                                 nilfs_end_page_io(fs_page, 0);
1878                                 fs_page = bh->b_page;
1879                         }
1880                 }
1881
1882                 if (!nilfs_segbuf_simplex(segbuf)) {
1883                         if (segbuf->sb_sum.flags & NILFS_SS_LOGBGN) {
1884                                 set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1885                                 sci->sc_lseg_stime = jiffies;
1886                         }
1887                         if (segbuf->sb_sum.flags & NILFS_SS_LOGEND)
1888                                 clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1889                 }
1890         }
1891         /*
1892          * Since pages may continue over multiple segment buffers,
1893          * end of the last page must be checked outside of the loop.
1894          */
1895         if (bd_page)
1896                 end_page_writeback(bd_page);
1897
1898         nilfs_end_page_io(fs_page, 0);
1899
1900         nilfs_drop_collected_inodes(&sci->sc_dirty_files);
1901
1902         if (nilfs_doing_gc())
1903                 nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
1904         else
1905                 nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
1906
1907         sci->sc_nblk_inc += sci->sc_nblk_this_inc;
1908
1909         segbuf = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1910         nilfs_set_next_segment(nilfs, segbuf);
1911
1912         if (update_sr) {
1913                 nilfs->ns_flushed_device = 0;
1914                 nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
1915                                        segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
1916
1917                 clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
1918                 clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1919                 set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1920                 nilfs_segctor_clear_metadata_dirty(sci);
1921         } else
1922                 clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1923 }
1924
1925 static int nilfs_segctor_wait(struct nilfs_sc_info *sci)
1926 {
1927         int ret;
1928
1929         ret = nilfs_wait_on_logs(&sci->sc_write_logs);
1930         if (!ret) {
1931                 nilfs_segctor_complete_write(sci);
1932                 nilfs_destroy_logs(&sci->sc_write_logs);
1933         }
1934         return ret;
1935 }
1936
1937 static int nilfs_segctor_collect_dirty_files(struct nilfs_sc_info *sci,
1938                                              struct the_nilfs *nilfs)
1939 {
1940         struct nilfs_inode_info *ii, *n;
1941         struct inode *ifile = sci->sc_root->ifile;
1942
1943         spin_lock(&nilfs->ns_inode_lock);
1944  retry:
1945         list_for_each_entry_safe(ii, n, &nilfs->ns_dirty_files, i_dirty) {
1946                 if (!ii->i_bh) {
1947                         struct buffer_head *ibh;
1948                         int err;
1949
1950                         spin_unlock(&nilfs->ns_inode_lock);
1951                         err = nilfs_ifile_get_inode_block(
1952                                 ifile, ii->vfs_inode.i_ino, &ibh);
1953                         if (unlikely(err)) {
1954                                 nilfs_msg(sci->sc_super, KERN_WARNING,
1955                                           "log writer: error %d getting inode block (ino=%lu)",
1956                                           err, ii->vfs_inode.i_ino);
1957                                 return err;
1958                         }
1959                         mark_buffer_dirty(ibh);
1960                         nilfs_mdt_mark_dirty(ifile);
1961                         spin_lock(&nilfs->ns_inode_lock);
1962                         if (likely(!ii->i_bh))
1963                                 ii->i_bh = ibh;
1964                         else
1965                                 brelse(ibh);
1966                         goto retry;
1967                 }
1968
1969                 clear_bit(NILFS_I_QUEUED, &ii->i_state);
1970                 set_bit(NILFS_I_BUSY, &ii->i_state);
1971                 list_move_tail(&ii->i_dirty, &sci->sc_dirty_files);
1972         }
1973         spin_unlock(&nilfs->ns_inode_lock);
1974
1975         return 0;
1976 }
1977
1978 static void nilfs_segctor_drop_written_files(struct nilfs_sc_info *sci,
1979                                              struct the_nilfs *nilfs)
1980 {
1981         struct nilfs_inode_info *ii, *n;
1982         int during_mount = !(sci->sc_super->s_flags & MS_ACTIVE);
1983         int defer_iput = false;
1984
1985         spin_lock(&nilfs->ns_inode_lock);
1986         list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
1987                 if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
1988                     test_bit(NILFS_I_DIRTY, &ii->i_state))
1989                         continue;
1990
1991                 clear_bit(NILFS_I_BUSY, &ii->i_state);
1992                 brelse(ii->i_bh);
1993                 ii->i_bh = NULL;
1994                 list_del_init(&ii->i_dirty);
1995                 if (!ii->vfs_inode.i_nlink || during_mount) {
1996                         /*
1997                          * Defer calling iput() to avoid deadlocks if
1998                          * i_nlink == 0 or mount is not yet finished.
1999                          */
2000                         list_add_tail(&ii->i_dirty, &sci->sc_iput_queue);
2001                         defer_iput = true;
2002                 } else {
2003                         spin_unlock(&nilfs->ns_inode_lock);
2004                         iput(&ii->vfs_inode);
2005                         spin_lock(&nilfs->ns_inode_lock);
2006                 }
2007         }
2008         spin_unlock(&nilfs->ns_inode_lock);
2009
2010         if (defer_iput)
2011                 schedule_work(&sci->sc_iput_work);
2012 }
2013
2014 /*
2015  * Main procedure of segment constructor
2016  */
2017 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
2018 {
2019         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2020         int err;
2021
2022         nilfs_sc_cstage_set(sci, NILFS_ST_INIT);
2023         sci->sc_cno = nilfs->ns_cno;
2024
2025         err = nilfs_segctor_collect_dirty_files(sci, nilfs);
2026         if (unlikely(err))
2027                 goto out;
2028
2029         if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
2030                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2031
2032         if (nilfs_segctor_clean(sci))
2033                 goto out;
2034
2035         do {
2036                 sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
2037
2038                 err = nilfs_segctor_begin_construction(sci, nilfs);
2039                 if (unlikely(err))
2040                         goto out;
2041
2042                 /* Update time stamp */
2043                 sci->sc_seg_ctime = get_seconds();
2044
2045                 err = nilfs_segctor_collect(sci, nilfs, mode);
2046                 if (unlikely(err))
2047                         goto failed;
2048
2049                 /* Avoid empty segment */
2050                 if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE &&
2051                     nilfs_segbuf_empty(sci->sc_curseg)) {
2052                         nilfs_segctor_abort_construction(sci, nilfs, 1);
2053                         goto out;
2054                 }
2055
2056                 err = nilfs_segctor_assign(sci, mode);
2057                 if (unlikely(err))
2058                         goto failed;
2059
2060                 if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2061                         nilfs_segctor_fill_in_file_bmap(sci);
2062
2063                 if (mode == SC_LSEG_SR &&
2064                     nilfs_sc_cstage_get(sci) >= NILFS_ST_CPFILE) {
2065                         err = nilfs_segctor_fill_in_checkpoint(sci);
2066                         if (unlikely(err))
2067                                 goto failed_to_write;
2068
2069                         nilfs_segctor_fill_in_super_root(sci, nilfs);
2070                 }
2071                 nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2072
2073                 /* Write partial segments */
2074                 nilfs_segctor_prepare_write(sci);
2075
2076                 nilfs_add_checksums_on_logs(&sci->sc_segbufs,
2077                                             nilfs->ns_crc_seed);
2078
2079                 err = nilfs_segctor_write(sci, nilfs);
2080                 if (unlikely(err))
2081                         goto failed_to_write;
2082
2083                 if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE ||
2084                     nilfs->ns_blocksize_bits != PAGE_SHIFT) {
2085                         /*
2086                          * At this point, we avoid double buffering
2087                          * for blocksize < pagesize because page dirty
2088                          * flag is turned off during write and dirty
2089                          * buffers are not properly collected for
2090                          * pages crossing over segments.
2091                          */
2092                         err = nilfs_segctor_wait(sci);
2093                         if (err)
2094                                 goto failed_to_write;
2095                 }
2096         } while (nilfs_sc_cstage_get(sci) != NILFS_ST_DONE);
2097
2098  out:
2099         nilfs_segctor_drop_written_files(sci, nilfs);
2100         return err;
2101
2102  failed_to_write:
2103         if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2104                 nilfs_redirty_inodes(&sci->sc_dirty_files);
2105
2106  failed:
2107         if (nilfs_doing_gc())
2108                 nilfs_redirty_inodes(&sci->sc_gc_inodes);
2109         nilfs_segctor_abort_construction(sci, nilfs, err);
2110         goto out;
2111 }
2112
2113 /**
2114  * nilfs_segctor_start_timer - set timer of background write
2115  * @sci: nilfs_sc_info
2116  *
2117  * If the timer has already been set, it ignores the new request.
2118  * This function MUST be called within a section locking the segment
2119  * semaphore.
2120  */
2121 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2122 {
2123         spin_lock(&sci->sc_state_lock);
2124         if (!(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2125                 sci->sc_timer.expires = jiffies + sci->sc_interval;
2126                 add_timer(&sci->sc_timer);
2127                 sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2128         }
2129         spin_unlock(&sci->sc_state_lock);
2130 }
2131
2132 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2133 {
2134         spin_lock(&sci->sc_state_lock);
2135         if (!(sci->sc_flush_request & BIT(bn))) {
2136                 unsigned long prev_req = sci->sc_flush_request;
2137
2138                 sci->sc_flush_request |= BIT(bn);
2139                 if (!prev_req)
2140                         wake_up(&sci->sc_wait_daemon);
2141         }
2142         spin_unlock(&sci->sc_state_lock);
2143 }
2144
2145 /**
2146  * nilfs_flush_segment - trigger a segment construction for resource control
2147  * @sb: super block
2148  * @ino: inode number of the file to be flushed out.
2149  */
2150 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2151 {
2152         struct the_nilfs *nilfs = sb->s_fs_info;
2153         struct nilfs_sc_info *sci = nilfs->ns_writer;
2154
2155         if (!sci || nilfs_doing_construction())
2156                 return;
2157         nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2158                                         /* assign bit 0 to data files */
2159 }
2160
2161 struct nilfs_segctor_wait_request {
2162         wait_queue_t    wq;
2163         __u32           seq;
2164         int             err;
2165         atomic_t        done;
2166 };
2167
2168 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2169 {
2170         struct nilfs_segctor_wait_request wait_req;
2171         int err = 0;
2172
2173         spin_lock(&sci->sc_state_lock);
2174         init_wait(&wait_req.wq);
2175         wait_req.err = 0;
2176         atomic_set(&wait_req.done, 0);
2177         wait_req.seq = ++sci->sc_seq_request;
2178         spin_unlock(&sci->sc_state_lock);
2179
2180         init_waitqueue_entry(&wait_req.wq, current);
2181         add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2182         set_current_state(TASK_INTERRUPTIBLE);
2183         wake_up(&sci->sc_wait_daemon);
2184
2185         for (;;) {
2186                 if (atomic_read(&wait_req.done)) {
2187                         err = wait_req.err;
2188                         break;
2189                 }
2190                 if (!signal_pending(current)) {
2191                         schedule();
2192                         continue;
2193                 }
2194                 err = -ERESTARTSYS;
2195                 break;
2196         }
2197         finish_wait(&sci->sc_wait_request, &wait_req.wq);
2198         return err;
2199 }
2200
2201 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2202 {
2203         struct nilfs_segctor_wait_request *wrq, *n;
2204         unsigned long flags;
2205
2206         spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2207         list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.task_list,
2208                                  wq.task_list) {
2209                 if (!atomic_read(&wrq->done) &&
2210                     nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2211                         wrq->err = err;
2212                         atomic_set(&wrq->done, 1);
2213                 }
2214                 if (atomic_read(&wrq->done)) {
2215                         wrq->wq.func(&wrq->wq,
2216                                      TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2217                                      0, NULL);
2218                 }
2219         }
2220         spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2221 }
2222
2223 /**
2224  * nilfs_construct_segment - construct a logical segment
2225  * @sb: super block
2226  *
2227  * Return Value: On success, 0 is retured. On errors, one of the following
2228  * negative error code is returned.
2229  *
2230  * %-EROFS - Read only filesystem.
2231  *
2232  * %-EIO - I/O error
2233  *
2234  * %-ENOSPC - No space left on device (only in a panic state).
2235  *
2236  * %-ERESTARTSYS - Interrupted.
2237  *
2238  * %-ENOMEM - Insufficient memory available.
2239  */
2240 int nilfs_construct_segment(struct super_block *sb)
2241 {
2242         struct the_nilfs *nilfs = sb->s_fs_info;
2243         struct nilfs_sc_info *sci = nilfs->ns_writer;
2244         struct nilfs_transaction_info *ti;
2245         int err;
2246
2247         if (!sci)
2248                 return -EROFS;
2249
2250         /* A call inside transactions causes a deadlock. */
2251         BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2252
2253         err = nilfs_segctor_sync(sci);
2254         return err;
2255 }
2256
2257 /**
2258  * nilfs_construct_dsync_segment - construct a data-only logical segment
2259  * @sb: super block
2260  * @inode: inode whose data blocks should be written out
2261  * @start: start byte offset
2262  * @end: end byte offset (inclusive)
2263  *
2264  * Return Value: On success, 0 is retured. On errors, one of the following
2265  * negative error code is returned.
2266  *
2267  * %-EROFS - Read only filesystem.
2268  *
2269  * %-EIO - I/O error
2270  *
2271  * %-ENOSPC - No space left on device (only in a panic state).
2272  *
2273  * %-ERESTARTSYS - Interrupted.
2274  *
2275  * %-ENOMEM - Insufficient memory available.
2276  */
2277 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2278                                   loff_t start, loff_t end)
2279 {
2280         struct the_nilfs *nilfs = sb->s_fs_info;
2281         struct nilfs_sc_info *sci = nilfs->ns_writer;
2282         struct nilfs_inode_info *ii;
2283         struct nilfs_transaction_info ti;
2284         int err = 0;
2285
2286         if (!sci)
2287                 return -EROFS;
2288
2289         nilfs_transaction_lock(sb, &ti, 0);
2290
2291         ii = NILFS_I(inode);
2292         if (test_bit(NILFS_I_INODE_SYNC, &ii->i_state) ||
2293             nilfs_test_opt(nilfs, STRICT_ORDER) ||
2294             test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2295             nilfs_discontinued(nilfs)) {
2296                 nilfs_transaction_unlock(sb);
2297                 err = nilfs_segctor_sync(sci);
2298                 return err;
2299         }
2300
2301         spin_lock(&nilfs->ns_inode_lock);
2302         if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2303             !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2304                 spin_unlock(&nilfs->ns_inode_lock);
2305                 nilfs_transaction_unlock(sb);
2306                 return 0;
2307         }
2308         spin_unlock(&nilfs->ns_inode_lock);
2309         sci->sc_dsync_inode = ii;
2310         sci->sc_dsync_start = start;
2311         sci->sc_dsync_end = end;
2312
2313         err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2314         if (!err)
2315                 nilfs->ns_flushed_device = 0;
2316
2317         nilfs_transaction_unlock(sb);
2318         return err;
2319 }
2320
2321 #define FLUSH_FILE_BIT  (0x1) /* data file only */
2322 #define FLUSH_DAT_BIT   BIT(NILFS_DAT_INO) /* DAT only */
2323
2324 /**
2325  * nilfs_segctor_accept - record accepted sequence count of log-write requests
2326  * @sci: segment constructor object
2327  */
2328 static void nilfs_segctor_accept(struct nilfs_sc_info *sci)
2329 {
2330         spin_lock(&sci->sc_state_lock);
2331         sci->sc_seq_accepted = sci->sc_seq_request;
2332         spin_unlock(&sci->sc_state_lock);
2333         del_timer_sync(&sci->sc_timer);
2334 }
2335
2336 /**
2337  * nilfs_segctor_notify - notify the result of request to caller threads
2338  * @sci: segment constructor object
2339  * @mode: mode of log forming
2340  * @err: error code to be notified
2341  */
2342 static void nilfs_segctor_notify(struct nilfs_sc_info *sci, int mode, int err)
2343 {
2344         /* Clear requests (even when the construction failed) */
2345         spin_lock(&sci->sc_state_lock);
2346
2347         if (mode == SC_LSEG_SR) {
2348                 sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2349                 sci->sc_seq_done = sci->sc_seq_accepted;
2350                 nilfs_segctor_wakeup(sci, err);
2351                 sci->sc_flush_request = 0;
2352         } else {
2353                 if (mode == SC_FLUSH_FILE)
2354                         sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2355                 else if (mode == SC_FLUSH_DAT)
2356                         sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2357
2358                 /* re-enable timer if checkpoint creation was not done */
2359                 if ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2360                     time_before(jiffies, sci->sc_timer.expires))
2361                         add_timer(&sci->sc_timer);
2362         }
2363         spin_unlock(&sci->sc_state_lock);
2364 }
2365
2366 /**
2367  * nilfs_segctor_construct - form logs and write them to disk
2368  * @sci: segment constructor object
2369  * @mode: mode of log forming
2370  */
2371 static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
2372 {
2373         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2374         struct nilfs_super_block **sbp;
2375         int err = 0;
2376
2377         nilfs_segctor_accept(sci);
2378
2379         if (nilfs_discontinued(nilfs))
2380                 mode = SC_LSEG_SR;
2381         if (!nilfs_segctor_confirm(sci))
2382                 err = nilfs_segctor_do_construct(sci, mode);
2383
2384         if (likely(!err)) {
2385                 if (mode != SC_FLUSH_DAT)
2386                         atomic_set(&nilfs->ns_ndirtyblks, 0);
2387                 if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2388                     nilfs_discontinued(nilfs)) {
2389                         down_write(&nilfs->ns_sem);
2390                         err = -EIO;
2391                         sbp = nilfs_prepare_super(sci->sc_super,
2392                                                   nilfs_sb_will_flip(nilfs));
2393                         if (likely(sbp)) {
2394                                 nilfs_set_log_cursor(sbp[0], nilfs);
2395                                 err = nilfs_commit_super(sci->sc_super,
2396                                                          NILFS_SB_COMMIT);
2397                         }
2398                         up_write(&nilfs->ns_sem);
2399                 }
2400         }
2401
2402         nilfs_segctor_notify(sci, mode, err);
2403         return err;
2404 }
2405
2406 static void nilfs_construction_timeout(unsigned long data)
2407 {
2408         struct task_struct *p = (struct task_struct *)data;
2409
2410         wake_up_process(p);
2411 }
2412
2413 static void
2414 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2415 {
2416         struct nilfs_inode_info *ii, *n;
2417
2418         list_for_each_entry_safe(ii, n, head, i_dirty) {
2419                 if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2420                         continue;
2421                 list_del_init(&ii->i_dirty);
2422                 truncate_inode_pages(&ii->vfs_inode.i_data, 0);
2423                 nilfs_btnode_cache_clear(&ii->i_btnode_cache);
2424                 iput(&ii->vfs_inode);
2425         }
2426 }
2427
2428 int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2429                          void **kbufs)
2430 {
2431         struct the_nilfs *nilfs = sb->s_fs_info;
2432         struct nilfs_sc_info *sci = nilfs->ns_writer;
2433         struct nilfs_transaction_info ti;
2434         int err;
2435
2436         if (unlikely(!sci))
2437                 return -EROFS;
2438
2439         nilfs_transaction_lock(sb, &ti, 1);
2440
2441         err = nilfs_mdt_save_to_shadow_map(nilfs->ns_dat);
2442         if (unlikely(err))
2443                 goto out_unlock;
2444
2445         err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2446         if (unlikely(err)) {
2447                 nilfs_mdt_restore_from_shadow_map(nilfs->ns_dat);
2448                 goto out_unlock;
2449         }
2450
2451         sci->sc_freesegs = kbufs[4];
2452         sci->sc_nfreesegs = argv[4].v_nmembs;
2453         list_splice_tail_init(&nilfs->ns_gc_inodes, &sci->sc_gc_inodes);
2454
2455         for (;;) {
2456                 err = nilfs_segctor_construct(sci, SC_LSEG_SR);
2457                 nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2458
2459                 if (likely(!err))
2460                         break;
2461
2462                 nilfs_msg(sb, KERN_WARNING, "error %d cleaning segments", err);
2463                 set_current_state(TASK_INTERRUPTIBLE);
2464                 schedule_timeout(sci->sc_interval);
2465         }
2466         if (nilfs_test_opt(nilfs, DISCARD)) {
2467                 int ret = nilfs_discard_segments(nilfs, sci->sc_freesegs,
2468                                                  sci->sc_nfreesegs);
2469                 if (ret) {
2470                         nilfs_msg(sb, KERN_WARNING,
2471                                   "error %d on discard request, turning discards off for the device",
2472                                   ret);
2473                         nilfs_clear_opt(nilfs, DISCARD);
2474                 }
2475         }
2476
2477  out_unlock:
2478         sci->sc_freesegs = NULL;
2479         sci->sc_nfreesegs = 0;
2480         nilfs_mdt_clear_shadow_map(nilfs->ns_dat);
2481         nilfs_transaction_unlock(sb);
2482         return err;
2483 }
2484
2485 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2486 {
2487         struct nilfs_transaction_info ti;
2488
2489         nilfs_transaction_lock(sci->sc_super, &ti, 0);
2490         nilfs_segctor_construct(sci, mode);
2491
2492         /*
2493          * Unclosed segment should be retried.  We do this using sc_timer.
2494          * Timeout of sc_timer will invoke complete construction which leads
2495          * to close the current logical segment.
2496          */
2497         if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2498                 nilfs_segctor_start_timer(sci);
2499
2500         nilfs_transaction_unlock(sci->sc_super);
2501 }
2502
2503 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2504 {
2505         int mode = 0;
2506
2507         spin_lock(&sci->sc_state_lock);
2508         mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2509                 SC_FLUSH_DAT : SC_FLUSH_FILE;
2510         spin_unlock(&sci->sc_state_lock);
2511
2512         if (mode) {
2513                 nilfs_segctor_do_construct(sci, mode);
2514
2515                 spin_lock(&sci->sc_state_lock);
2516                 sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2517                         ~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2518                 spin_unlock(&sci->sc_state_lock);
2519         }
2520         clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2521 }
2522
2523 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2524 {
2525         if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2526             time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2527                 if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2528                         return SC_FLUSH_FILE;
2529                 else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2530                         return SC_FLUSH_DAT;
2531         }
2532         return SC_LSEG_SR;
2533 }
2534
2535 /**
2536  * nilfs_segctor_thread - main loop of the segment constructor thread.
2537  * @arg: pointer to a struct nilfs_sc_info.
2538  *
2539  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2540  * to execute segment constructions.
2541  */
2542 static int nilfs_segctor_thread(void *arg)
2543 {
2544         struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2545         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2546         int timeout = 0;
2547
2548         sci->sc_timer.data = (unsigned long)current;
2549         sci->sc_timer.function = nilfs_construction_timeout;
2550
2551         /* start sync. */
2552         sci->sc_task = current;
2553         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2554         nilfs_msg(sci->sc_super, KERN_INFO,
2555                   "segctord starting. Construction interval = %lu seconds, CP frequency < %lu seconds",
2556                   sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2557
2558         spin_lock(&sci->sc_state_lock);
2559  loop:
2560         for (;;) {
2561                 int mode;
2562
2563                 if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2564                         goto end_thread;
2565
2566                 if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2567                         mode = SC_LSEG_SR;
2568                 else if (sci->sc_flush_request)
2569                         mode = nilfs_segctor_flush_mode(sci);
2570                 else
2571                         break;
2572
2573                 spin_unlock(&sci->sc_state_lock);
2574                 nilfs_segctor_thread_construct(sci, mode);
2575                 spin_lock(&sci->sc_state_lock);
2576                 timeout = 0;
2577         }
2578
2579
2580         if (freezing(current)) {
2581                 spin_unlock(&sci->sc_state_lock);
2582                 try_to_freeze();
2583                 spin_lock(&sci->sc_state_lock);
2584         } else {
2585                 DEFINE_WAIT(wait);
2586                 int should_sleep = 1;
2587
2588                 prepare_to_wait(&sci->sc_wait_daemon, &wait,
2589                                 TASK_INTERRUPTIBLE);
2590
2591                 if (sci->sc_seq_request != sci->sc_seq_done)
2592                         should_sleep = 0;
2593                 else if (sci->sc_flush_request)
2594                         should_sleep = 0;
2595                 else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2596                         should_sleep = time_before(jiffies,
2597                                         sci->sc_timer.expires);
2598
2599                 if (should_sleep) {
2600                         spin_unlock(&sci->sc_state_lock);
2601                         schedule();
2602                         spin_lock(&sci->sc_state_lock);
2603                 }
2604                 finish_wait(&sci->sc_wait_daemon, &wait);
2605                 timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2606                            time_after_eq(jiffies, sci->sc_timer.expires));
2607
2608                 if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
2609                         set_nilfs_discontinued(nilfs);
2610         }
2611         goto loop;
2612
2613  end_thread:
2614         spin_unlock(&sci->sc_state_lock);
2615
2616         /* end sync. */
2617         sci->sc_task = NULL;
2618         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2619         return 0;
2620 }
2621
2622 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2623 {
2624         struct task_struct *t;
2625
2626         t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2627         if (IS_ERR(t)) {
2628                 int err = PTR_ERR(t);
2629
2630                 nilfs_msg(sci->sc_super, KERN_ERR,
2631                           "error %d creating segctord thread", err);
2632                 return err;
2633         }
2634         wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2635         return 0;
2636 }
2637
2638 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2639         __acquires(&sci->sc_state_lock)
2640         __releases(&sci->sc_state_lock)
2641 {
2642         sci->sc_state |= NILFS_SEGCTOR_QUIT;
2643
2644         while (sci->sc_task) {
2645                 wake_up(&sci->sc_wait_daemon);
2646                 spin_unlock(&sci->sc_state_lock);
2647                 wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2648                 spin_lock(&sci->sc_state_lock);
2649         }
2650 }
2651
2652 /*
2653  * Setup & clean-up functions
2654  */
2655 static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
2656                                                struct nilfs_root *root)
2657 {
2658         struct the_nilfs *nilfs = sb->s_fs_info;
2659         struct nilfs_sc_info *sci;
2660
2661         sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2662         if (!sci)
2663                 return NULL;
2664
2665         sci->sc_super = sb;
2666
2667         nilfs_get_root(root);
2668         sci->sc_root = root;
2669
2670         init_waitqueue_head(&sci->sc_wait_request);
2671         init_waitqueue_head(&sci->sc_wait_daemon);
2672         init_waitqueue_head(&sci->sc_wait_task);
2673         spin_lock_init(&sci->sc_state_lock);
2674         INIT_LIST_HEAD(&sci->sc_dirty_files);
2675         INIT_LIST_HEAD(&sci->sc_segbufs);
2676         INIT_LIST_HEAD(&sci->sc_write_logs);
2677         INIT_LIST_HEAD(&sci->sc_gc_inodes);
2678         INIT_LIST_HEAD(&sci->sc_iput_queue);
2679         INIT_WORK(&sci->sc_iput_work, nilfs_iput_work_func);
2680         init_timer(&sci->sc_timer);
2681
2682         sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2683         sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2684         sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2685
2686         if (nilfs->ns_interval)
2687                 sci->sc_interval = HZ * nilfs->ns_interval;
2688         if (nilfs->ns_watermark)
2689                 sci->sc_watermark = nilfs->ns_watermark;
2690         return sci;
2691 }
2692
2693 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2694 {
2695         int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2696
2697         /*
2698          * The segctord thread was stopped and its timer was removed.
2699          * But some tasks remain.
2700          */
2701         do {
2702                 struct nilfs_transaction_info ti;
2703
2704                 nilfs_transaction_lock(sci->sc_super, &ti, 0);
2705                 ret = nilfs_segctor_construct(sci, SC_LSEG_SR);
2706                 nilfs_transaction_unlock(sci->sc_super);
2707
2708                 flush_work(&sci->sc_iput_work);
2709
2710         } while (ret && retrycount-- > 0);
2711 }
2712
2713 /**
2714  * nilfs_segctor_destroy - destroy the segment constructor.
2715  * @sci: nilfs_sc_info
2716  *
2717  * nilfs_segctor_destroy() kills the segctord thread and frees
2718  * the nilfs_sc_info struct.
2719  * Caller must hold the segment semaphore.
2720  */
2721 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2722 {
2723         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2724         int flag;
2725
2726         up_write(&nilfs->ns_segctor_sem);
2727
2728         spin_lock(&sci->sc_state_lock);
2729         nilfs_segctor_kill_thread(sci);
2730         flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2731                 || sci->sc_seq_request != sci->sc_seq_done);
2732         spin_unlock(&sci->sc_state_lock);
2733
2734         if (flush_work(&sci->sc_iput_work))
2735                 flag = true;
2736
2737         if (flag || !nilfs_segctor_confirm(sci))
2738                 nilfs_segctor_write_out(sci);
2739
2740         if (!list_empty(&sci->sc_dirty_files)) {
2741                 nilfs_msg(sci->sc_super, KERN_WARNING,
2742                           "disposed unprocessed dirty file(s) when stopping log writer");
2743                 nilfs_dispose_list(nilfs, &sci->sc_dirty_files, 1);
2744         }
2745
2746         if (!list_empty(&sci->sc_iput_queue)) {
2747                 nilfs_msg(sci->sc_super, KERN_WARNING,
2748                           "disposed unprocessed inode(s) in iput queue when stopping log writer");
2749                 nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 1);
2750         }
2751
2752         WARN_ON(!list_empty(&sci->sc_segbufs));
2753         WARN_ON(!list_empty(&sci->sc_write_logs));
2754
2755         nilfs_put_root(sci->sc_root);
2756
2757         down_write(&nilfs->ns_segctor_sem);
2758
2759         del_timer_sync(&sci->sc_timer);
2760         kfree(sci);
2761 }
2762
2763 /**
2764  * nilfs_attach_log_writer - attach log writer
2765  * @sb: super block instance
2766  * @root: root object of the current filesystem tree
2767  *
2768  * This allocates a log writer object, initializes it, and starts the
2769  * log writer.
2770  *
2771  * Return Value: On success, 0 is returned. On error, one of the following
2772  * negative error code is returned.
2773  *
2774  * %-ENOMEM - Insufficient memory available.
2775  */
2776 int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
2777 {
2778         struct the_nilfs *nilfs = sb->s_fs_info;
2779         int err;
2780
2781         if (nilfs->ns_writer) {
2782                 /*
2783                  * This happens if the filesystem was remounted
2784                  * read/write after nilfs_error degenerated it into a
2785                  * read-only mount.
2786                  */
2787                 nilfs_detach_log_writer(sb);
2788         }
2789
2790         nilfs->ns_writer = nilfs_segctor_new(sb, root);
2791         if (!nilfs->ns_writer)
2792                 return -ENOMEM;
2793
2794         err = nilfs_segctor_start_thread(nilfs->ns_writer);
2795         if (err) {
2796                 kfree(nilfs->ns_writer);
2797                 nilfs->ns_writer = NULL;
2798         }
2799         return err;
2800 }
2801
2802 /**
2803  * nilfs_detach_log_writer - destroy log writer
2804  * @sb: super block instance
2805  *
2806  * This kills log writer daemon, frees the log writer object, and
2807  * destroys list of dirty files.
2808  */
2809 void nilfs_detach_log_writer(struct super_block *sb)
2810 {
2811         struct the_nilfs *nilfs = sb->s_fs_info;
2812         LIST_HEAD(garbage_list);
2813
2814         down_write(&nilfs->ns_segctor_sem);
2815         if (nilfs->ns_writer) {
2816                 nilfs_segctor_destroy(nilfs->ns_writer);
2817                 nilfs->ns_writer = NULL;
2818         }
2819
2820         /* Force to free the list of dirty files */
2821         spin_lock(&nilfs->ns_inode_lock);
2822         if (!list_empty(&nilfs->ns_dirty_files)) {
2823                 list_splice_init(&nilfs->ns_dirty_files, &garbage_list);
2824                 nilfs_msg(sb, KERN_WARNING,
2825                           "disposed unprocessed dirty file(s) when detaching log writer");
2826         }
2827         spin_unlock(&nilfs->ns_inode_lock);
2828         up_write(&nilfs->ns_segctor_sem);
2829
2830         nilfs_dispose_list(nilfs, &garbage_list, 1);
2831 }