fs/gfs2/log.c

   1 /*
   2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3  * Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
   4  *
   5  * This copyrighted material is made available to anyone wishing to use,
   6  * modify, copy, or redistribute it subject to the terms and conditions
   7  * of the GNU General Public License version 2.
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/slab.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/completion.h>
  14 #include <linux/buffer_head.h>
  15 #include <linux/gfs2_ondisk.h>
  16 #include <linux/crc32.h>
  17 #include <linux/delay.h>
  18 #include <linux/kthread.h>
  19 #include <linux/freezer.h>
  20 #include <linux/bio.h>
  21 #include <linux/blkdev.h>
  22 #include <linux/writeback.h>
  23 #include <linux/list_sort.h>
  24
  25 #include "gfs2.h"
  26 #include "incore.h"
  27 #include "bmap.h"
  28 #include "glock.h"
  29 #include "log.h"
  30 #include "lops.h"
  31 #include "meta_io.h"
  32 #include "util.h"
  33 #include "dir.h"
  34 #include "trace_gfs2.h"
  35
  36 /**
  37  * gfs2_struct2blk - compute stuff
  38  * @sdp: the filesystem
  39  * @nstruct: the number of structures
  40  * @ssize: the size of the structures
  41  *
  42  * Compute the number of log descriptor blocks needed to hold a certain number
  43  * of structures of a certain size.
  44  *
  45  * Returns: the number of blocks needed (minimum is always 1)
  46  */
  47
  48 unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct,
  49                              unsigned int ssize)
  50 {
  51         unsigned int blks;
  52         unsigned int first, second;
  53
  54         blks = 1;
  55         first = (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_log_descriptor)) / ssize;
  56
  57         if (nstruct > first) {
  58                 second = (sdp->sd_sb.sb_bsize -
  59                           sizeof(struct gfs2_meta_header)) / ssize;
  60                 blks += DIV_ROUND_UP(nstruct - first, second);
  61         }
  62
  63         return blks;
  64 }
  65
  66 /**
  67  * gfs2_remove_from_ail - Remove an entry from the ail lists, updating counters
  68  * @mapping: The associated mapping (maybe NULL)
  69  * @bd: The gfs2_bufdata to remove
  70  *
  71  * The ail lock _must_ be held when calling this function
  72  *
  73  */
  74
  75 void gfs2_remove_from_ail(struct gfs2_bufdata *bd)
  76 {
  77         bd->bd_tr = NULL;
  78         list_del_init(&bd->bd_ail_st_list);
  79         list_del_init(&bd->bd_ail_gl_list);
  80         atomic_dec(&bd->bd_gl->gl_ail_count);
  81         brelse(bd->bd_bh);
  82 }
  83
  84 /**
  85  * gfs2_ail1_start_one - Start I/O on a part of the AIL
  86  * @sdp: the filesystem
  87  * @wbc: The writeback control structure
  88  * @ai: The ail structure
  89  *
  90  */
  91
  92 static int gfs2_ail1_start_one(struct gfs2_sbd *sdp,
  93                                struct writeback_control *wbc,
  94                                struct gfs2_trans *tr)
  95 __releases(&sdp->sd_ail_lock)
  96 __acquires(&sdp->sd_ail_lock)
  97 {
  98         struct gfs2_glock *gl = NULL;
  99         struct address_space *mapping;
 100         struct gfs2_bufdata *bd, *s;
 101         struct buffer_head *bh;
 102
 103         list_for_each_entry_safe_reverse(bd, s, &tr->tr_ail1_list, bd_ail_st_list) {
 104                 bh = bd->bd_bh;
 105
 106                 gfs2_assert(sdp, bd->bd_tr == tr);
 107
 108                 if (!buffer_busy(bh)) {
 109                         if (!buffer_uptodate(bh))
 110                                 gfs2_io_error_bh(sdp, bh);
 111                         list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
 112                         continue;
 113                 }
 114
 115                 if (!buffer_dirty(bh))
 116                         continue;
 117                 if (gl == bd->bd_gl)
 118                         continue;
 119                 gl = bd->bd_gl;
 120                 list_move(&bd->bd_ail_st_list, &tr->tr_ail1_list);
 121                 mapping = bh->b_page->mapping;
 122                 if (!mapping)
 123                         continue;
 124                 spin_unlock(&sdp->sd_ail_lock);
 125                 generic_writepages(mapping, wbc);
 126                 spin_lock(&sdp->sd_ail_lock);
 127                 if (wbc->nr_to_write <= 0)
 128                         break;
 129                 return 1;
 130         }
 131
 132         return 0;
 133 }
 134
 135
 136 /**
 137  * gfs2_ail1_flush - start writeback of some ail1 entries
 138  * @sdp: The super block
 139  * @wbc: The writeback control structure
 140  *
 141  * Writes back some ail1 entries, according to the limits in the
 142  * writeback control structure
 143  */
 144
 145 void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc)
 146 {
 147         struct list_head *head = &sdp->sd_ail1_list;
 148         struct gfs2_trans *tr;
 149         struct blk_plug plug;
 150
 151         trace_gfs2_ail_flush(sdp, wbc, 1);
 152         blk_start_plug(&plug);
 153         spin_lock(&sdp->sd_ail_lock);
 154 restart:
 155         list_for_each_entry_reverse(tr, head, tr_list) {
 156                 if (wbc->nr_to_write <= 0)
 157                         break;
 158                 if (gfs2_ail1_start_one(sdp, wbc, tr))
 159                         goto restart;
 160         }
 161         spin_unlock(&sdp->sd_ail_lock);
 162         blk_finish_plug(&plug);
 163         trace_gfs2_ail_flush(sdp, wbc, 0);
 164 }
 165
 166 /**
 167  * gfs2_ail1_start - start writeback of all ail1 entries
 168  * @sdp: The superblock
 169  */
 170
 171 static void gfs2_ail1_start(struct gfs2_sbd *sdp)
 172 {
 173         struct writeback_control wbc = {
 174                 .sync_mode = WB_SYNC_NONE,
 175                 .nr_to_write = LONG_MAX,
 176                 .range_start = 0,
 177                 .range_end = LLONG_MAX,
 178         };
 179
 180         return gfs2_ail1_flush(sdp, &wbc);
 181 }
 182
 183 /**
 184  * gfs2_ail1_empty_one - Check whether or not a trans in the AIL has been synced
 185  * @sdp: the filesystem
 186  * @ai: the AIL entry
 187  *
 188  */
 189
 190 static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 191 {
 192         struct gfs2_bufdata *bd, *s;
 193         struct buffer_head *bh;
 194
 195         list_for_each_entry_safe_reverse(bd, s, &tr->tr_ail1_list,
 196                                          bd_ail_st_list) {
 197                 bh = bd->bd_bh;
 198                 gfs2_assert(sdp, bd->bd_tr == tr);
 199                 if (buffer_busy(bh))
 200                         continue;
 201                 if (!buffer_uptodate(bh))
 202                         gfs2_io_error_bh(sdp, bh);
 203                 list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
 204         }
 205
 206 }
 207
 208 /**
 209  * gfs2_ail1_empty - Try to empty the ail1 lists
 210  * @sdp: The superblock
 211  *
 212  * Tries to empty the ail1 lists, starting with the oldest first
 213  */
 214
 215 static int gfs2_ail1_empty(struct gfs2_sbd *sdp)
 216 {
 217         struct gfs2_trans *tr, *s;
 218         int oldest_tr = 1;
 219         int ret;
 220
 221         spin_lock(&sdp->sd_ail_lock);
 222         list_for_each_entry_safe_reverse(tr, s, &sdp->sd_ail1_list, tr_list) {
 223                 gfs2_ail1_empty_one(sdp, tr);
 224                 if (list_empty(&tr->tr_ail1_list) && oldest_tr)
 225                         list_move(&tr->tr_list, &sdp->sd_ail2_list);
 226                 else
 227                         oldest_tr = 0;
 228         }
 229         ret = list_empty(&sdp->sd_ail1_list);
 230         spin_unlock(&sdp->sd_ail_lock);
 231
 232         return ret;
 233 }
 234
 235 static void gfs2_ail1_wait(struct gfs2_sbd *sdp)
 236 {
 237         struct gfs2_trans *tr;
 238         struct gfs2_bufdata *bd;
 239         struct buffer_head *bh;
 240
 241         spin_lock(&sdp->sd_ail_lock);
 242         list_for_each_entry_reverse(tr, &sdp->sd_ail1_list, tr_list) {
 243                 list_for_each_entry(bd, &tr->tr_ail1_list, bd_ail_st_list) {
 244                         bh = bd->bd_bh;
 245                         if (!buffer_locked(bh))
 246                                 continue;
 247                         get_bh(bh);
 248                         spin_unlock(&sdp->sd_ail_lock);
 249                         wait_on_buffer(bh);
 250                         brelse(bh);
 251                         return;
 252                 }
 253         }
 254         spin_unlock(&sdp->sd_ail_lock);
 255 }
 256
 257 /**
 258  * gfs2_ail2_empty_one - Check whether or not a trans in the AIL has been synced
 259  * @sdp: the filesystem
 260  * @ai: the AIL entry
 261  *
 262  */
 263
 264 static void gfs2_ail2_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 265 {
 266         struct list_head *head = &tr->tr_ail2_list;
 267         struct gfs2_bufdata *bd;
 268
 269         while (!list_empty(head)) {
 270                 bd = list_entry(head->prev, struct gfs2_bufdata,
 271                                 bd_ail_st_list);
 272                 gfs2_assert(sdp, bd->bd_tr == tr);
 273                 gfs2_remove_from_ail(bd);
 274         }
 275 }
 276
 277 static void ail2_empty(struct gfs2_sbd *sdp, unsigned int new_tail)
 278 {
 279         struct gfs2_trans *tr, *safe;
 280         unsigned int old_tail = sdp->sd_log_tail;
 281         int wrap = (new_tail < old_tail);
 282         int a, b, rm;
 283
 284         spin_lock(&sdp->sd_ail_lock);
 285
 286         list_for_each_entry_safe(tr, safe, &sdp->sd_ail2_list, tr_list) {
 287                 a = (old_tail <= tr->tr_first);
 288                 b = (tr->tr_first < new_tail);
 289                 rm = (wrap) ? (a || b) : (a && b);
 290                 if (!rm)
 291                         continue;
 292
 293                 gfs2_ail2_empty_one(sdp, tr);
 294                 list_del(&tr->tr_list);
 295                 gfs2_assert_warn(sdp, list_empty(&tr->tr_ail1_list));
 296                 gfs2_assert_warn(sdp, list_empty(&tr->tr_ail2_list));
 297                 kfree(tr);
 298         }
 299
 300         spin_unlock(&sdp->sd_ail_lock);
 301 }
 302
 303 /**
 304  * gfs2_log_release - Release a given number of log blocks
 305  * @sdp: The GFS2 superblock
 306  * @blks: The number of blocks
 307  *
 308  */
 309
 310 void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks)
 311 {
 312
 313         atomic_add(blks, &sdp->sd_log_blks_free);
 314         trace_gfs2_log_blocks(sdp, blks);
 315         gfs2_assert_withdraw(sdp, atomic_read(&sdp->sd_log_blks_free) <=
 316                                   sdp->sd_jdesc->jd_blocks);
 317         up_read(&sdp->sd_log_flush_lock);
 318 }
 319
 320 /**
 321  * gfs2_log_reserve - Make a log reservation
 322  * @sdp: The GFS2 superblock
 323  * @blks: The number of blocks to reserve
 324  *
 325  * Note that we never give out the last few blocks of the journal. Thats
 326  * due to the fact that there is a small number of header blocks
 327  * associated with each log flush. The exact number can't be known until
 328  * flush time, so we ensure that we have just enough free blocks at all
 329  * times to avoid running out during a log flush.
 330  *
 331  * We no longer flush the log here, instead we wake up logd to do that
 332  * for us. To avoid the thundering herd and to ensure that we deal fairly
 333  * with queued waiters, we use an exclusive wait. This means that when we
 334  * get woken with enough journal space to get our reservation, we need to
 335  * wake the next waiter on the list.
 336  *
 337  * Returns: errno
 338  */
 339
 340 int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks)
 341 {
 342         int ret = 0;
 343         unsigned reserved_blks = 7 * (4096 / sdp->sd_vfs->s_blocksize);
 344         unsigned wanted = blks + reserved_blks;
 345         DEFINE_WAIT(wait);
 346         int did_wait = 0;
 347         unsigned int free_blocks;
 348
 349         if (gfs2_assert_warn(sdp, blks) ||
 350             gfs2_assert_warn(sdp, blks <= sdp->sd_jdesc->jd_blocks))
 351                 return -EINVAL;
 352         atomic_add(blks, &sdp->sd_log_blks_needed);
 353 retry:
 354         free_blocks = atomic_read(&sdp->sd_log_blks_free);
 355         if (unlikely(free_blocks <= wanted)) {
 356                 do {
 357                         prepare_to_wait_exclusive(&sdp->sd_log_waitq, &wait,
 358                                         TASK_UNINTERRUPTIBLE);
 359                         wake_up(&sdp->sd_logd_waitq);
 360                         did_wait = 1;
 361                         if (atomic_read(&sdp->sd_log_blks_free) <= wanted)
 362                                 io_schedule();
 363                         free_blocks = atomic_read(&sdp->sd_log_blks_free);
 364                 } while(free_blocks <= wanted);
 365                 finish_wait(&sdp->sd_log_waitq, &wait);
 366         }
 367         atomic_inc(&sdp->sd_reserving_log);
 368         if (atomic_cmpxchg(&sdp->sd_log_blks_free, free_blocks,
 369                                 free_blocks - blks) != free_blocks) {
 370                 if (atomic_dec_and_test(&sdp->sd_reserving_log))
 371                         wake_up(&sdp->sd_reserving_log_wait);
 372                 goto retry;
 373         }
 374         atomic_sub(blks, &sdp->sd_log_blks_needed);
 375         trace_gfs2_log_blocks(sdp, -blks);
 376
 377         /*
 378          * If we waited, then so might others, wake them up _after_ we get
 379          * our share of the log.
 380          */
 381         if (unlikely(did_wait))
 382                 wake_up(&sdp->sd_log_waitq);
 383
 384         down_read(&sdp->sd_log_flush_lock);
 385         if (unlikely(!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))) {
 386                 gfs2_log_release(sdp, blks);
 387                 ret = -EROFS;
 388         }
 389         if (atomic_dec_and_test(&sdp->sd_reserving_log))
 390                 wake_up(&sdp->sd_reserving_log_wait);
 391         return ret;
 392 }
 393
 394 /**
 395  * log_distance - Compute distance between two journal blocks
 396  * @sdp: The GFS2 superblock
 397  * @newer: The most recent journal block of the pair
 398  * @older: The older journal block of the pair
 399  *
 400  *   Compute the distance (in the journal direction) between two
 401  *   blocks in the journal
 402  *
 403  * Returns: the distance in blocks
 404  */
 405
 406 static inline unsigned int log_distance(struct gfs2_sbd *sdp, unsigned int newer,
 407                                         unsigned int older)
 408 {
 409         int dist;
 410
 411         dist = newer - older;
 412         if (dist < 0)
 413                 dist += sdp->sd_jdesc->jd_blocks;
 414
 415         return dist;
 416 }
 417
 418 /**
 419  * calc_reserved - Calculate the number of blocks to reserve when
 420  *                 refunding a transaction's unused buffers.
 421  * @sdp: The GFS2 superblock
 422  *
 423  * This is complex.  We need to reserve room for all our currently used
 424  * metadata buffers (e.g. normal file I/O rewriting file time stamps) and
 425  * all our journaled data buffers for journaled files (e.g. files in the
 426  * meta_fs like rindex, or files for which chattr +j was done.)
 427  * If we don't reserve enough space, gfs2_log_refund and gfs2_log_flush
 428  * will count it as free space (sd_log_blks_free) and corruption will follow.
 429  *
 430  * We can have metadata bufs and jdata bufs in the same journal.  So each
 431  * type gets its own log header, for which we need to reserve a block.
 432  * In fact, each type has the potential for needing more than one header
 433  * in cases where we have more buffers than will fit on a journal page.
 434  * Metadata journal entries take up half the space of journaled buffer entries.
 435  * Thus, metadata entries have buf_limit (502) and journaled buffers have
 436  * databuf_limit (251) before they cause a wrap around.
 437  *
 438  * Also, we need to reserve blocks for revoke journal entries and one for an
 439  * overall header for the lot.
 440  *
 441  * Returns: the number of blocks reserved
 442  */
 443 static unsigned int calc_reserved(struct gfs2_sbd *sdp)
 444 {
 445         unsigned int reserved = 0;
 446         unsigned int mbuf;
 447         unsigned int dbuf;
 448         struct gfs2_trans *tr = sdp->sd_log_tr;
 449
 450         if (tr) {
 451                 mbuf = tr->tr_num_buf_new - tr->tr_num_buf_rm;
 452                 dbuf = tr->tr_num_databuf_new - tr->tr_num_databuf_rm;
 453                 reserved = mbuf + dbuf;
 454                 /* Account for header blocks */
 455                 reserved += DIV_ROUND_UP(mbuf, buf_limit(sdp));
 456                 reserved += DIV_ROUND_UP(dbuf, databuf_limit(sdp));
 457         }
 458
 459         if (sdp->sd_log_commited_revoke > 0)
 460                 reserved += gfs2_struct2blk(sdp, sdp->sd_log_commited_revoke,
 461                                           sizeof(u64));
 462         /* One for the overall header */
 463         if (reserved)
 464                 reserved++;
 465         return reserved;
 466 }
 467
 468 static unsigned int current_tail(struct gfs2_sbd *sdp)
 469 {
 470         struct gfs2_trans *tr;
 471         unsigned int tail;
 472
 473         spin_lock(&sdp->sd_ail_lock);
 474
 475         if (list_empty(&sdp->sd_ail1_list)) {
 476                 tail = sdp->sd_log_head;
 477         } else {
 478                 tr = list_entry(sdp->sd_ail1_list.prev, struct gfs2_trans,
 479                                 tr_list);
 480                 tail = tr->tr_first;
 481         }
 482
 483         spin_unlock(&sdp->sd_ail_lock);
 484
 485         return tail;
 486 }
 487
 488 static void log_pull_tail(struct gfs2_sbd *sdp, unsigned int new_tail)
 489 {
 490         unsigned int dist = log_distance(sdp, new_tail, sdp->sd_log_tail);
 491
 492         ail2_empty(sdp, new_tail);
 493
 494         atomic_add(dist, &sdp->sd_log_blks_free);
 495         trace_gfs2_log_blocks(sdp, dist);
 496         gfs2_assert_withdraw(sdp, atomic_read(&sdp->sd_log_blks_free) <=
 497                              sdp->sd_jdesc->jd_blocks);
 498
 499         sdp->sd_log_tail = new_tail;
 500 }
 501
 502
 503 static void log_flush_wait(struct gfs2_sbd *sdp)
 504 {
 505         DEFINE_WAIT(wait);
 506
 507         if (atomic_read(&sdp->sd_log_in_flight)) {
 508                 do {
 509                         prepare_to_wait(&sdp->sd_log_flush_wait, &wait,
 510                                         TASK_UNINTERRUPTIBLE);
 511                         if (atomic_read(&sdp->sd_log_in_flight))
 512                                 io_schedule();
 513                 } while(atomic_read(&sdp->sd_log_in_flight));
 514                 finish_wait(&sdp->sd_log_flush_wait, &wait);
 515         }
 516 }
 517
 518 static int ip_cmp(void *priv, struct list_head *a, struct list_head *b)
 519 {
 520         struct gfs2_inode *ipa, *ipb;
 521
 522         ipa = list_entry(a, struct gfs2_inode, i_ordered);
 523         ipb = list_entry(b, struct gfs2_inode, i_ordered);
 524
 525         if (ipa->i_no_addr < ipb->i_no_addr)
 526                 return -1;
 527         if (ipa->i_no_addr > ipb->i_no_addr)
 528                 return 1;
 529         return 0;
 530 }
 531
 532 static void gfs2_ordered_write(struct gfs2_sbd *sdp)
 533 {
 534         struct gfs2_inode *ip;
 535         LIST_HEAD(written);
 536
 537         spin_lock(&sdp->sd_ordered_lock);
 538         list_sort(NULL, &sdp->sd_log_le_ordered, &ip_cmp);
 539         while (!list_empty(&sdp->sd_log_le_ordered)) {
 540                 ip = list_entry(sdp->sd_log_le_ordered.next, struct gfs2_inode, i_ordered);
 541                 list_move(&ip->i_ordered, &written);
 542                 if (ip->i_inode.i_mapping->nrpages == 0)
 543                         continue;
 544                 spin_unlock(&sdp->sd_ordered_lock);
 545                 filemap_fdatawrite(ip->i_inode.i_mapping);
 546                 spin_lock(&sdp->sd_ordered_lock);
 547         }
 548         list_splice(&written, &sdp->sd_log_le_ordered);
 549         spin_unlock(&sdp->sd_ordered_lock);
 550 }
 551
 552 static void gfs2_ordered_wait(struct gfs2_sbd *sdp)
 553 {
 554         struct gfs2_inode *ip;
 555
 556         spin_lock(&sdp->sd_ordered_lock);
 557         while (!list_empty(&sdp->sd_log_le_ordered)) {
 558                 ip = list_entry(sdp->sd_log_le_ordered.next, struct gfs2_inode, i_ordered);
 559                 list_del(&ip->i_ordered);
 560                 WARN_ON(!test_and_clear_bit(GIF_ORDERED, &ip->i_flags));
 561                 if (ip->i_inode.i_mapping->nrpages == 0)
 562                         continue;
 563                 spin_unlock(&sdp->sd_ordered_lock);
 564                 filemap_fdatawait(ip->i_inode.i_mapping);
 565                 spin_lock(&sdp->sd_ordered_lock);
 566         }
 567         spin_unlock(&sdp->sd_ordered_lock);
 568 }
 569
 570 void gfs2_ordered_del_inode(struct gfs2_inode *ip)
 571 {
 572         struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 573
 574         spin_lock(&sdp->sd_ordered_lock);
 575         if (test_and_clear_bit(GIF_ORDERED, &ip->i_flags))
 576                 list_del(&ip->i_ordered);
 577         spin_unlock(&sdp->sd_ordered_lock);
 578 }
 579
 580 void gfs2_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
 581 {
 582         struct buffer_head *bh = bd->bd_bh;
 583         struct gfs2_glock *gl = bd->bd_gl;
 584
 585         bh->b_private = NULL;
 586         bd->bd_blkno = bh->b_blocknr;
 587         gfs2_remove_from_ail(bd); /* drops ref on bh */
 588         bd->bd_bh = NULL;
 589         bd->bd_ops = &gfs2_revoke_lops;
 590         sdp->sd_log_num_revoke++;
 591         atomic_inc(&gl->gl_revokes);
 592         set_bit(GLF_LFLUSH, &gl->gl_flags);
 593         list_add(&bd->bd_list, &sdp->sd_log_le_revoke);
 594 }
 595
 596 void gfs2_write_revokes(struct gfs2_sbd *sdp)
 597 {
 598         struct gfs2_trans *tr;
 599         struct gfs2_bufdata *bd, *tmp;
 600         int have_revokes = 0;
 601         int max_revokes = (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_log_descriptor)) / sizeof(u64);
 602
 603         gfs2_ail1_empty(sdp);
 604         spin_lock(&sdp->sd_ail_lock);
 605         list_for_each_entry(tr, &sdp->sd_ail1_list, tr_list) {
 606                 list_for_each_entry(bd, &tr->tr_ail2_list, bd_ail_st_list) {
 607                         if (list_empty(&bd->bd_list)) {
 608                                 have_revokes = 1;
 609                                 goto done;
 610                         }
 611                 }
 612         }
 613 done:
 614         spin_unlock(&sdp->sd_ail_lock);
 615         if (have_revokes == 0)
 616                 return;
 617         while (sdp->sd_log_num_revoke > max_revokes)
 618                 max_revokes += (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_meta_header)) / sizeof(u64);
 619         max_revokes -= sdp->sd_log_num_revoke;
 620         if (!sdp->sd_log_num_revoke) {
 621                 atomic_dec(&sdp->sd_log_blks_free);
 622                 /* If no blocks have been reserved, we need to also
 623                  * reserve a block for the header */
 624                 if (!sdp->sd_log_blks_reserved)
 625                         atomic_dec(&sdp->sd_log_blks_free);
 626         }
 627         gfs2_log_lock(sdp);
 628         spin_lock(&sdp->sd_ail_lock);
 629         list_for_each_entry(tr, &sdp->sd_ail1_list, tr_list) {
 630                 list_for_each_entry_safe(bd, tmp, &tr->tr_ail2_list, bd_ail_st_list) {
 631                         if (max_revokes == 0)
 632                                 goto out_of_blocks;
 633                         if (!list_empty(&bd->bd_list))
 634                                 continue;
 635                         gfs2_add_revoke(sdp, bd);
 636                         max_revokes--;
 637                 }
 638         }
 639 out_of_blocks:
 640         spin_unlock(&sdp->sd_ail_lock);
 641         gfs2_log_unlock(sdp);
 642
 643         if (!sdp->sd_log_num_revoke) {
 644                 atomic_inc(&sdp->sd_log_blks_free);
 645                 if (!sdp->sd_log_blks_reserved)
 646                         atomic_inc(&sdp->sd_log_blks_free);
 647         }
 648 }
 649
 650 /**
 651  * log_write_header - Get and initialize a journal header buffer
 652  * @sdp: The GFS2 superblock
 653  *
 654  * Returns: the initialized log buffer descriptor
 655  */
 656
 657 static void log_write_header(struct gfs2_sbd *sdp, u32 flags)
 658 {
 659         struct gfs2_log_header *lh;
 660         unsigned int tail;
 661         u32 hash;
 662         int op_flags = REQ_PREFLUSH | REQ_FUA | REQ_META;
 663         struct page *page = mempool_alloc(gfs2_page_pool, GFP_NOIO);
 664         enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);
 665         lh = page_address(page);
 666         clear_page(lh);
 667
 668         gfs2_assert_withdraw(sdp, (state != SFS_FROZEN));
 669
 670         tail = current_tail(sdp);
 671
 672         lh->lh_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
 673         lh->lh_header.mh_type = cpu_to_be32(GFS2_METATYPE_LH);
 674         lh->lh_header.__pad0 = cpu_to_be64(0);
 675         lh->lh_header.mh_format = cpu_to_be32(GFS2_FORMAT_LH);
 676         lh->lh_header.mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);
 677         lh->lh_sequence = cpu_to_be64(sdp->sd_log_sequence++);
 678         lh->lh_flags = cpu_to_be32(flags);
 679         lh->lh_tail = cpu_to_be32(tail);
 680         lh->lh_blkno = cpu_to_be32(sdp->sd_log_flush_head);
 681         hash = gfs2_disk_hash(page_address(page), sizeof(struct gfs2_log_header));
 682         lh->lh_hash = cpu_to_be32(hash);
 683
 684         if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags)) {
 685                 gfs2_ordered_wait(sdp);
 686                 log_flush_wait(sdp);
 687                 op_flags = REQ_SYNC | REQ_META | REQ_PRIO;
 688         }
 689
 690         sdp->sd_log_idle = (tail == sdp->sd_log_flush_head);
 691         gfs2_log_write_page(sdp, page);
 692         gfs2_log_flush_bio(sdp, REQ_OP_WRITE, op_flags);
 693         log_flush_wait(sdp);
 694
 695         if (sdp->sd_log_tail != tail)
 696                 log_pull_tail(sdp, tail);
 697 }
 698
 699 /**
 700  * gfs2_log_flush - flush incore transaction(s)
 701  * @sdp: the filesystem
 702  * @gl: The glock structure to flush.  If NULL, flush the whole incore log
 703  *
 704  */
 705
 706 void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl,
 707                     enum gfs2_flush_type type)
 708 {
 709         struct gfs2_trans *tr;
 710         enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);
 711
 712         down_write(&sdp->sd_log_flush_lock);
 713
 714         /* Log might have been flushed while we waited for the flush lock */
 715         if (gl && !test_bit(GLF_LFLUSH, &gl->gl_flags)) {
 716                 up_write(&sdp->sd_log_flush_lock);
 717                 return;
 718         }
 719         trace_gfs2_log_flush(sdp, 1);
 720
 721         if (type == SHUTDOWN_FLUSH)
 722                 clear_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
 723
 724         sdp->sd_log_flush_head = sdp->sd_log_head;
 725         sdp->sd_log_flush_wrapped = 0;
 726         tr = sdp->sd_log_tr;
 727         if (tr) {
 728                 sdp->sd_log_tr = NULL;
 729                 INIT_LIST_HEAD(&tr->tr_ail1_list);
 730                 INIT_LIST_HEAD(&tr->tr_ail2_list);
 731                 tr->tr_first = sdp->sd_log_flush_head;
 732                 if (unlikely (state == SFS_FROZEN))
 733                         gfs2_assert_withdraw(sdp, !tr->tr_num_buf_new && !tr->tr_num_databuf_new);
 734         }
 735
 736         if (unlikely(state == SFS_FROZEN))
 737                 gfs2_assert_withdraw(sdp, !sdp->sd_log_num_revoke);
 738         gfs2_assert_withdraw(sdp,
 739                         sdp->sd_log_num_revoke == sdp->sd_log_commited_revoke);
 740
 741         gfs2_ordered_write(sdp);
 742         lops_before_commit(sdp, tr);
 743         gfs2_log_flush_bio(sdp, REQ_OP_WRITE, 0);
 744
 745         if (sdp->sd_log_head != sdp->sd_log_flush_head) {
 746                 log_flush_wait(sdp);
 747                 log_write_header(sdp, 0);
 748         } else if (sdp->sd_log_tail != current_tail(sdp) && !sdp->sd_log_idle){
 749                 atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */
 750                 trace_gfs2_log_blocks(sdp, -1);
 751                 log_write_header(sdp, 0);
 752         }
 753         lops_after_commit(sdp, tr);
 754
 755         gfs2_log_lock(sdp);
 756         sdp->sd_log_head = sdp->sd_log_flush_head;
 757         sdp->sd_log_blks_reserved = 0;
 758         sdp->sd_log_commited_revoke = 0;
 759
 760         spin_lock(&sdp->sd_ail_lock);
 761         if (tr && !list_empty(&tr->tr_ail1_list)) {
 762                 list_add(&tr->tr_list, &sdp->sd_ail1_list);
 763                 tr = NULL;
 764         }
 765         spin_unlock(&sdp->sd_ail_lock);
 766         gfs2_log_unlock(sdp);
 767
 768         if (type != NORMAL_FLUSH) {
 769                 if (!sdp->sd_log_idle) {
 770                         for (;;) {
 771                                 gfs2_ail1_start(sdp);
 772                                 gfs2_ail1_wait(sdp);
 773                                 if (gfs2_ail1_empty(sdp))
 774                                         break;
 775                         }
 776                         atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */
 777                         trace_gfs2_log_blocks(sdp, -1);
 778                         sdp->sd_log_flush_wrapped = 0;
 779                         log_write_header(sdp, 0);
 780                         sdp->sd_log_head = sdp->sd_log_flush_head;
 781                 }
 782                 if (type == SHUTDOWN_FLUSH || type == FREEZE_FLUSH)
 783                         gfs2_log_shutdown(sdp);
 784                 if (type == FREEZE_FLUSH)
 785                         atomic_set(&sdp->sd_freeze_state, SFS_FROZEN);
 786         }
 787
 788         trace_gfs2_log_flush(sdp, 0);
 789         up_write(&sdp->sd_log_flush_lock);
 790
 791         kfree(tr);
 792 }
 793
 794 /**
 795  * gfs2_merge_trans - Merge a new transaction into a cached transaction
 796  * @old: Original transaction to be expanded
 797  * @new: New transaction to be merged
 798  */
 799
 800 static void gfs2_merge_trans(struct gfs2_trans *old, struct gfs2_trans *new)
 801 {
 802         WARN_ON_ONCE(!test_bit(TR_ATTACHED, &old->tr_flags));
 803
 804         old->tr_num_buf_new     += new->tr_num_buf_new;
 805         old->tr_num_databuf_new += new->tr_num_databuf_new;
 806         old->tr_num_buf_rm      += new->tr_num_buf_rm;
 807         old->tr_num_databuf_rm  += new->tr_num_databuf_rm;
 808         old->tr_num_revoke      += new->tr_num_revoke;
 809         old->tr_num_revoke_rm   += new->tr_num_revoke_rm;
 810
 811         list_splice_tail_init(&new->tr_databuf, &old->tr_databuf);
 812         list_splice_tail_init(&new->tr_buf, &old->tr_buf);
 813 }
 814
 815 static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 816 {
 817         unsigned int reserved;
 818         unsigned int unused;
 819         unsigned int maxres;
 820
 821         gfs2_log_lock(sdp);
 822
 823         if (sdp->sd_log_tr) {
 824                 gfs2_merge_trans(sdp->sd_log_tr, tr);
 825         } else if (tr->tr_num_buf_new || tr->tr_num_databuf_new) {
 826                 gfs2_assert_withdraw(sdp, test_bit(TR_ALLOCED, &tr->tr_flags));
 827                 sdp->sd_log_tr = tr;
 828                 set_bit(TR_ATTACHED, &tr->tr_flags);
 829         }
 830
 831         sdp->sd_log_commited_revoke += tr->tr_num_revoke - tr->tr_num_revoke_rm;
 832         reserved = calc_reserved(sdp);
 833         maxres = sdp->sd_log_blks_reserved + tr->tr_reserved;
 834         gfs2_assert_withdraw(sdp, maxres >= reserved);
 835         unused = maxres - reserved;
 836         atomic_add(unused, &sdp->sd_log_blks_free);
 837         trace_gfs2_log_blocks(sdp, unused);
 838         gfs2_assert_withdraw(sdp, atomic_read(&sdp->sd_log_blks_free) <=
 839                              sdp->sd_jdesc->jd_blocks);
 840         sdp->sd_log_blks_reserved = reserved;
 841
 842         gfs2_log_unlock(sdp);
 843 }
 844
 845 /**
 846  * gfs2_log_commit - Commit a transaction to the log
 847  * @sdp: the filesystem
 848  * @tr: the transaction
 849  *
 850  * We wake up gfs2_logd if the number of pinned blocks exceed thresh1
 851  * or the total number of used blocks (pinned blocks plus AIL blocks)
 852  * is greater than thresh2.
 853  *
 854  * At mount time thresh1 is 1/3rd of journal size, thresh2 is 2/3rd of
 855  * journal size.
 856  *
 857  * Returns: errno
 858  */
 859
 860 void gfs2_log_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 861 {
 862         log_refund(sdp, tr);
 863
 864         if (atomic_read(&sdp->sd_log_pinned) > atomic_read(&sdp->sd_log_thresh1) ||
 865             ((sdp->sd_jdesc->jd_blocks - atomic_read(&sdp->sd_log_blks_free)) >
 866             atomic_read(&sdp->sd_log_thresh2)))
 867                 wake_up(&sdp->sd_logd_waitq);
 868 }
 869
 870 /**
 871  * gfs2_log_shutdown - write a shutdown header into a journal
 872  * @sdp: the filesystem
 873  *
 874  */
 875
 876 void gfs2_log_shutdown(struct gfs2_sbd *sdp)
 877 {
 878         gfs2_assert_withdraw(sdp, !sdp->sd_log_blks_reserved);
 879         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_revoke);
 880         gfs2_assert_withdraw(sdp, list_empty(&sdp->sd_ail1_list));
 881
 882         sdp->sd_log_flush_head = sdp->sd_log_head;
 883         sdp->sd_log_flush_wrapped = 0;
 884
 885         log_write_header(sdp, GFS2_LOG_HEAD_UNMOUNT);
 886
 887         gfs2_assert_warn(sdp, sdp->sd_log_head == sdp->sd_log_tail);
 888         gfs2_assert_warn(sdp, list_empty(&sdp->sd_ail2_list));
 889
 890         sdp->sd_log_head = sdp->sd_log_flush_head;
 891         sdp->sd_log_tail = sdp->sd_log_head;
 892 }
 893
 894 static inline int gfs2_jrnl_flush_reqd(struct gfs2_sbd *sdp)
 895 {
 896         return (atomic_read(&sdp->sd_log_pinned) +
 897                 atomic_read(&sdp->sd_log_blks_needed) >=
 898                 atomic_read(&sdp->sd_log_thresh1));
 899 }
 900
 901 static inline int gfs2_ail_flush_reqd(struct gfs2_sbd *sdp)
 902 {
 903         unsigned int used_blocks = sdp->sd_jdesc->jd_blocks - atomic_read(&sdp->sd_log_blks_free);
 904         return used_blocks + atomic_read(&sdp->sd_log_blks_needed) >=
 905                 atomic_read(&sdp->sd_log_thresh2);
 906 }
 907
 908 /**
 909  * gfs2_logd - Update log tail as Active Items get flushed to in-place blocks
 910  * @sdp: Pointer to GFS2 superblock
 911  *
 912  * Also, periodically check to make sure that we're using the most recent
 913  * journal index.
 914  */
 915
 916 int gfs2_logd(void *data)
 917 {
 918         struct gfs2_sbd *sdp = data;
 919         unsigned long t = 1;
 920         DEFINE_WAIT(wait);
 921         bool did_flush;
 922
 923         while (!kthread_should_stop()) {
 924
 925                 did_flush = false;
 926                 if (gfs2_jrnl_flush_reqd(sdp) || t == 0) {
 927                         gfs2_ail1_empty(sdp);
 928                         gfs2_log_flush(sdp, NULL, NORMAL_FLUSH);
 929                         did_flush = true;
 930                 }
 931
 932                 if (gfs2_ail_flush_reqd(sdp)) {
 933                         gfs2_ail1_start(sdp);
 934                         gfs2_ail1_wait(sdp);
 935                         gfs2_ail1_empty(sdp);
 936                         gfs2_log_flush(sdp, NULL, NORMAL_FLUSH);
 937                         did_flush = true;
 938                 }
 939
 940                 if (!gfs2_ail_flush_reqd(sdp) || did_flush)
 941                         wake_up(&sdp->sd_log_waitq);
 942
 943                 t = gfs2_tune_get(sdp, gt_logd_secs) * HZ;
 944
 945                 try_to_freeze();
 946
 947                 do {
 948                         prepare_to_wait(&sdp->sd_logd_waitq, &wait,
 949                                         TASK_INTERRUPTIBLE);
 950                         if (!gfs2_ail_flush_reqd(sdp) &&
 951                             !gfs2_jrnl_flush_reqd(sdp) &&
 952                             !kthread_should_stop())
 953                                 t = schedule_timeout(t);
 954                 } while(t && !gfs2_ail_flush_reqd(sdp) &&
 955                         !gfs2_jrnl_flush_reqd(sdp) &&
 956                         !kthread_should_stop());
 957                 finish_wait(&sdp->sd_logd_waitq, &wait);
 958         }
 959
 960         return 0;
 961 }
 962