git.oblomov.eu Git - linux-2.6/blob - fs/gfs2/super.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/crc32.h>
  16 #include <linux/gfs2_ondisk.h>
  17 #include <linux/bio.h>
  18 #include <linux/lm_interface.h>
  19
  20 #include "gfs2.h"
  21 #include "incore.h"
  22 #include "bmap.h"
  23 #include "dir.h"
  24 #include "glock.h"
  25 #include "glops.h"
  26 #include "inode.h"
  27 #include "log.h"
  28 #include "meta_io.h"
  29 #include "quota.h"
  30 #include "recovery.h"
  31 #include "rgrp.h"
  32 #include "super.h"
  33 #include "trans.h"
  34 #include "util.h"
  35
  36 /**
  37  * gfs2_jindex_hold - Grab a lock on the jindex
  38  * @sdp: The GFS2 superblock
  39  * @ji_gh: the holder for the jindex glock
  40  *
  41  * This is very similar to the gfs2_rindex_hold() function, except that
  42  * in general we hold the jindex lock for longer periods of time and
  43  * we grab it far less frequently (in general) then the rgrp lock.
  44  *
  45  * Returns: errno
  46  */
  47
  48 int gfs2_jindex_hold(struct gfs2_sbd *sdp, struct gfs2_holder *ji_gh)
  49 {
  50         struct gfs2_inode *dip = GFS2_I(sdp->sd_jindex);
  51         struct qstr name;
  52         char buf[20];
  53         struct gfs2_jdesc *jd;
  54         int error;
  55
  56         name.name = buf;
  57
  58         mutex_lock(&sdp->sd_jindex_mutex);
  59
  60         for (;;) {
  61                 error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, ji_gh);
  62                 if (error)
  63                         break;
  64
  65                 name.len = sprintf(buf, "journal%u", sdp->sd_journals);
  66                 name.hash = gfs2_disk_hash(name.name, name.len);
  67
  68                 error = gfs2_dir_check(sdp->sd_jindex, &name, NULL);
  69                 if (error == -ENOENT) {
  70                         error = 0;
  71                         break;
  72                 }
  73
  74                 gfs2_glock_dq_uninit(ji_gh);
  75
  76                 if (error)
  77                         break;
  78
  79                 error = -ENOMEM;
  80                 jd = kzalloc(sizeof(struct gfs2_jdesc), GFP_KERNEL);
  81                 if (!jd)
  82                         break;
  83
  84                 INIT_LIST_HEAD(&jd->extent_list);
  85                 jd->jd_inode = gfs2_lookupi(sdp->sd_jindex, &name, 1);
  86                 if (!jd->jd_inode || IS_ERR(jd->jd_inode)) {
  87                         if (!jd->jd_inode)
  88                                 error = -ENOENT;
  89                         else
  90                                 error = PTR_ERR(jd->jd_inode);
  91                         kfree(jd);
  92                         break;
  93                 }
  94
  95                 spin_lock(&sdp->sd_jindex_spin);
  96                 jd->jd_jid = sdp->sd_journals++;
  97                 list_add_tail(&jd->jd_list, &sdp->sd_jindex_list);
  98                 spin_unlock(&sdp->sd_jindex_spin);
  99         }
 100
 101         mutex_unlock(&sdp->sd_jindex_mutex);
 102
 103         return error;
 104 }
 105
 106 /**
 107  * gfs2_jindex_free - Clear all the journal index information
 108  * @sdp: The GFS2 superblock
 109  *
 110  */
 111
 112 void gfs2_jindex_free(struct gfs2_sbd *sdp)
 113 {
 114         struct list_head list, *head;
 115         struct gfs2_jdesc *jd;
 116         struct gfs2_journal_extent *jext;
 117
 118         spin_lock(&sdp->sd_jindex_spin);
 119         list_add(&list, &sdp->sd_jindex_list);
 120         list_del_init(&sdp->sd_jindex_list);
 121         sdp->sd_journals = 0;
 122         spin_unlock(&sdp->sd_jindex_spin);
 123
 124         while (!list_empty(&list)) {
 125                 jd = list_entry(list.next, struct gfs2_jdesc, jd_list);
 126                 head = &jd->extent_list;
 127                 while (!list_empty(head)) {
 128                         jext = list_entry(head->next,
 129                                           struct gfs2_journal_extent,
 130                                           extent_list);
 131                         list_del(&jext->extent_list);
 132                         kfree(jext);
 133                 }
 134                 list_del(&jd->jd_list);
 135                 iput(jd->jd_inode);
 136                 kfree(jd);
 137         }
 138 }
 139
 140 static struct gfs2_jdesc *jdesc_find_i(struct list_head *head, unsigned int jid)
 141 {
 142         struct gfs2_jdesc *jd;
 143         int found = 0;
 144
 145         list_for_each_entry(jd, head, jd_list) {
 146                 if (jd->jd_jid == jid) {
 147                         found = 1;
 148                         break;
 149                 }
 150         }
 151
 152         if (!found)
 153                 jd = NULL;
 154
 155         return jd;
 156 }
 157
 158 struct gfs2_jdesc *gfs2_jdesc_find(struct gfs2_sbd *sdp, unsigned int jid)
 159 {
 160         struct gfs2_jdesc *jd;
 161
 162         spin_lock(&sdp->sd_jindex_spin);
 163         jd = jdesc_find_i(&sdp->sd_jindex_list, jid);
 164         spin_unlock(&sdp->sd_jindex_spin);
 165
 166         return jd;
 167 }
 168
 169 void gfs2_jdesc_make_dirty(struct gfs2_sbd *sdp, unsigned int jid)
 170 {
 171         struct gfs2_jdesc *jd;
 172
 173         spin_lock(&sdp->sd_jindex_spin);
 174         jd = jdesc_find_i(&sdp->sd_jindex_list, jid);
 175         if (jd)
 176                 jd->jd_dirty = 1;
 177         spin_unlock(&sdp->sd_jindex_spin);
 178 }
 179
 180 struct gfs2_jdesc *gfs2_jdesc_find_dirty(struct gfs2_sbd *sdp)
 181 {
 182         struct gfs2_jdesc *jd;
 183         int found = 0;
 184
 185         spin_lock(&sdp->sd_jindex_spin);
 186
 187         list_for_each_entry(jd, &sdp->sd_jindex_list, jd_list) {
 188                 if (jd->jd_dirty) {
 189                         jd->jd_dirty = 0;
 190                         found = 1;
 191                         break;
 192                 }
 193         }
 194         spin_unlock(&sdp->sd_jindex_spin);
 195
 196         if (!found)
 197                 jd = NULL;
 198
 199         return jd;
 200 }
 201
 202 int gfs2_jdesc_check(struct gfs2_jdesc *jd)
 203 {
 204         struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
 205         struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 206         int ar;
 207         int error;
 208
 209         if (ip->i_di.di_size < (8 << 20) || ip->i_di.di_size > (1 << 30) ||
 210             (ip->i_di.di_size & (sdp->sd_sb.sb_bsize - 1))) {
 211                 gfs2_consist_inode(ip);
 212                 return -EIO;
 213         }
 214         jd->jd_blocks = ip->i_di.di_size >> sdp->sd_sb.sb_bsize_shift;
 215
 216         error = gfs2_write_alloc_required(ip, 0, ip->i_di.di_size, &ar);
 217         if (!error && ar) {
 218                 gfs2_consist_inode(ip);
 219                 error = -EIO;
 220         }
 221
 222         return error;
 223 }
 224
 225 /**
 226  * gfs2_make_fs_rw - Turn a Read-Only FS into a Read-Write one
 227  * @sdp: the filesystem
 228  *
 229  * Returns: errno
 230  */
 231
 232 int gfs2_make_fs_rw(struct gfs2_sbd *sdp)
 233 {
 234         struct gfs2_inode *ip = GFS2_I(sdp->sd_jdesc->jd_inode);
 235         struct gfs2_glock *j_gl = ip->i_gl;
 236         struct gfs2_holder t_gh;
 237         struct gfs2_log_header_host head;
 238         int error;
 239
 240         error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_SHARED, 0, &t_gh);
 241         if (error)
 242                 return error;
 243
 244         j_gl->gl_ops->go_inval(j_gl, DIO_METADATA);
 245
 246         error = gfs2_find_jhead(sdp->sd_jdesc, &head);
 247         if (error)
 248                 goto fail;
 249
 250         if (!(head.lh_flags & GFS2_LOG_HEAD_UNMOUNT)) {
 251                 gfs2_consist(sdp);
 252                 error = -EIO;
 253                 goto fail;
 254         }
 255
 256         /*  Initialize some head of the log stuff  */
 257         sdp->sd_log_sequence = head.lh_sequence + 1;
 258         gfs2_log_pointers_init(sdp, head.lh_blkno);
 259
 260         error = gfs2_quota_init(sdp);
 261         if (error)
 262                 goto fail;
 263
 264         set_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
 265
 266         gfs2_glock_dq_uninit(&t_gh);
 267
 268         return 0;
 269
 270 fail:
 271         t_gh.gh_flags |= GL_NOCACHE;
 272         gfs2_glock_dq_uninit(&t_gh);
 273
 274         return error;
 275 }
 276
 277 static void gfs2_statfs_change_in(struct gfs2_statfs_change_host *sc, const void *buf)
 278 {
 279         const struct gfs2_statfs_change *str = buf;
 280
 281         sc->sc_total = be64_to_cpu(str->sc_total);
 282         sc->sc_free = be64_to_cpu(str->sc_free);
 283         sc->sc_dinodes = be64_to_cpu(str->sc_dinodes);
 284 }
 285
 286 static void gfs2_statfs_change_out(const struct gfs2_statfs_change_host *sc, void *buf)
 287 {
 288         struct gfs2_statfs_change *str = buf;
 289
 290         str->sc_total = cpu_to_be64(sc->sc_total);
 291         str->sc_free = cpu_to_be64(sc->sc_free);
 292         str->sc_dinodes = cpu_to_be64(sc->sc_dinodes);
 293 }
 294
 295 int gfs2_statfs_init(struct gfs2_sbd *sdp)
 296 {
 297         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 298         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 299         struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
 300         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 301         struct buffer_head *m_bh, *l_bh;
 302         struct gfs2_holder gh;
 303         int error;
 304
 305         error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE, GL_NOCACHE,
 306                                    &gh);
 307         if (error)
 308                 return error;
 309
 310         error = gfs2_meta_inode_buffer(m_ip, &m_bh);
 311         if (error)
 312                 goto out;
 313
 314         if (sdp->sd_args.ar_spectator) {
 315                 spin_lock(&sdp->sd_statfs_spin);
 316                 gfs2_statfs_change_in(m_sc, m_bh->b_data +
 317                                       sizeof(struct gfs2_dinode));
 318                 spin_unlock(&sdp->sd_statfs_spin);
 319         } else {
 320                 error = gfs2_meta_inode_buffer(l_ip, &l_bh);
 321                 if (error)
 322                         goto out_m_bh;
 323
 324                 spin_lock(&sdp->sd_statfs_spin);
 325                 gfs2_statfs_change_in(m_sc, m_bh->b_data +
 326                                       sizeof(struct gfs2_dinode));
 327                 gfs2_statfs_change_in(l_sc, l_bh->b_data +
 328                                       sizeof(struct gfs2_dinode));
 329                 spin_unlock(&sdp->sd_statfs_spin);
 330
 331                 brelse(l_bh);
 332         }
 333
 334 out_m_bh:
 335         brelse(m_bh);
 336 out:
 337         gfs2_glock_dq_uninit(&gh);
 338         return 0;
 339 }
 340
 341 void gfs2_statfs_change(struct gfs2_sbd *sdp, s64 total, s64 free,
 342                         s64 dinodes)
 343 {
 344         struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
 345         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 346         struct buffer_head *l_bh;
 347         int error;
 348
 349         error = gfs2_meta_inode_buffer(l_ip, &l_bh);
 350         if (error)
 351                 return;
 352
 353         gfs2_trans_add_bh(l_ip->i_gl, l_bh, 1);
 354
 355         spin_lock(&sdp->sd_statfs_spin);
 356         l_sc->sc_total += total;
 357         l_sc->sc_free += free;
 358         l_sc->sc_dinodes += dinodes;
 359         gfs2_statfs_change_out(l_sc, l_bh->b_data + sizeof(struct gfs2_dinode));
 360         spin_unlock(&sdp->sd_statfs_spin);
 361
 362         brelse(l_bh);
 363 }
 364
 365 int gfs2_statfs_sync(struct gfs2_sbd *sdp)
 366 {
 367         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 368         struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
 369         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 370         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 371         struct gfs2_holder gh;
 372         struct buffer_head *m_bh, *l_bh;
 373         int error;
 374
 375         error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE, GL_NOCACHE,
 376                                    &gh);
 377         if (error)
 378                 return error;
 379
 380         error = gfs2_meta_inode_buffer(m_ip, &m_bh);
 381         if (error)
 382                 goto out;
 383
 384         spin_lock(&sdp->sd_statfs_spin);
 385         gfs2_statfs_change_in(m_sc, m_bh->b_data +
 386                               sizeof(struct gfs2_dinode));
 387         if (!l_sc->sc_total && !l_sc->sc_free && !l_sc->sc_dinodes) {
 388                 spin_unlock(&sdp->sd_statfs_spin);
 389                 goto out_bh;
 390         }
 391         spin_unlock(&sdp->sd_statfs_spin);
 392
 393         error = gfs2_meta_inode_buffer(l_ip, &l_bh);
 394         if (error)
 395                 goto out_bh;
 396
 397         error = gfs2_trans_begin(sdp, 2 * RES_DINODE, 0);
 398         if (error)
 399                 goto out_bh2;
 400
 401         gfs2_trans_add_bh(l_ip->i_gl, l_bh, 1);
 402
 403         spin_lock(&sdp->sd_statfs_spin);
 404         m_sc->sc_total += l_sc->sc_total;
 405         m_sc->sc_free += l_sc->sc_free;
 406         m_sc->sc_dinodes += l_sc->sc_dinodes;
 407         memset(l_sc, 0, sizeof(struct gfs2_statfs_change));
 408         memset(l_bh->b_data + sizeof(struct gfs2_dinode),
 409                0, sizeof(struct gfs2_statfs_change));
 410         spin_unlock(&sdp->sd_statfs_spin);
 411
 412         gfs2_trans_add_bh(m_ip->i_gl, m_bh, 1);
 413         gfs2_statfs_change_out(m_sc, m_bh->b_data + sizeof(struct gfs2_dinode));
 414
 415         gfs2_trans_end(sdp);
 416
 417 out_bh2:
 418         brelse(l_bh);
 419 out_bh:
 420         brelse(m_bh);
 421 out:
 422         gfs2_glock_dq_uninit(&gh);
 423         return error;
 424 }
 425
 426 /**
 427  * gfs2_statfs_i - Do a statfs
 428  * @sdp: the filesystem
 429  * @sg: the sg structure
 430  *
 431  * Returns: errno
 432  */
 433
 434 int gfs2_statfs_i(struct gfs2_sbd *sdp, struct gfs2_statfs_change_host *sc)
 435 {
 436         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 437         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 438
 439         spin_lock(&sdp->sd_statfs_spin);
 440
 441         *sc = *m_sc;
 442         sc->sc_total += l_sc->sc_total;
 443         sc->sc_free += l_sc->sc_free;
 444         sc->sc_dinodes += l_sc->sc_dinodes;
 445
 446         spin_unlock(&sdp->sd_statfs_spin);
 447
 448         if (sc->sc_free < 0)
 449                 sc->sc_free = 0;
 450         if (sc->sc_free > sc->sc_total)
 451                 sc->sc_free = sc->sc_total;
 452         if (sc->sc_dinodes < 0)
 453                 sc->sc_dinodes = 0;
 454
 455         return 0;
 456 }
 457
 458 /**
 459  * statfs_fill - fill in the sg for a given RG
 460  * @rgd: the RG
 461  * @sc: the sc structure
 462  *
 463  * Returns: 0 on success, -ESTALE if the LVB is invalid
 464  */
 465
 466 static int statfs_slow_fill(struct gfs2_rgrpd *rgd,
 467                             struct gfs2_statfs_change_host *sc)
 468 {
 469         gfs2_rgrp_verify(rgd);
 470         sc->sc_total += rgd->rd_data;
 471         sc->sc_free += rgd->rd_rg.rg_free;
 472         sc->sc_dinodes += rgd->rd_rg.rg_dinodes;
 473         return 0;
 474 }
 475
 476 /**
 477  * gfs2_statfs_slow - Stat a filesystem using asynchronous locking
 478  * @sdp: the filesystem
 479  * @sc: the sc info that will be returned
 480  *
 481  * Any error (other than a signal) will cause this routine to fall back
 482  * to the synchronous version.
 483  *
 484  * FIXME: This really shouldn't busy wait like this.
 485  *
 486  * Returns: errno
 487  */
 488
 489 int gfs2_statfs_slow(struct gfs2_sbd *sdp, struct gfs2_statfs_change_host *sc)
 490 {
 491         struct gfs2_holder ri_gh;
 492         struct gfs2_rgrpd *rgd_next;
 493         struct gfs2_holder *gha, *gh;
 494         unsigned int slots = 64;
 495         unsigned int x;
 496         int done;
 497         int error = 0, err;
 498
 499         memset(sc, 0, sizeof(struct gfs2_statfs_change_host));
 500         gha = kcalloc(slots, sizeof(struct gfs2_holder), GFP_KERNEL);
 501         if (!gha)
 502                 return -ENOMEM;
 503
 504         error = gfs2_rindex_hold(sdp, &ri_gh);
 505         if (error)
 506                 goto out;
 507
 508         rgd_next = gfs2_rgrpd_get_first(sdp);
 509
 510         for (;;) {
 511                 done = 1;
 512
 513                 for (x = 0; x < slots; x++) {
 514                         gh = gha + x;
 515
 516                         if (gh->gh_gl && gfs2_glock_poll(gh)) {
 517                                 err = gfs2_glock_wait(gh);
 518                                 if (err) {
 519                                         gfs2_holder_uninit(gh);
 520                                         error = err;
 521                                 } else {
 522                                         if (!error)
 523                                                 error = statfs_slow_fill(
 524                                                         gh->gh_gl->gl_object, sc);
 525                                         gfs2_glock_dq_uninit(gh);
 526                                 }
 527                         }
 528
 529                         if (gh->gh_gl)
 530                                 done = 0;
 531                         else if (rgd_next && !error) {
 532                                 error = gfs2_glock_nq_init(rgd_next->rd_gl,
 533                                                            LM_ST_SHARED,
 534                                                            GL_ASYNC,
 535                                                            gh);
 536                                 rgd_next = gfs2_rgrpd_get_next(rgd_next);
 537                                 done = 0;
 538                         }
 539
 540                         if (signal_pending(current))
 541                                 error = -ERESTARTSYS;
 542                 }
 543
 544                 if (done)
 545                         break;
 546
 547                 yield();
 548         }
 549
 550         gfs2_glock_dq_uninit(&ri_gh);
 551
 552 out:
 553         kfree(gha);
 554         return error;
 555 }
 556
 557 struct lfcc {
 558         struct list_head list;
 559         struct gfs2_holder gh;
 560 };
 561
 562 /**
 563  * gfs2_lock_fs_check_clean - Stop all writes to the FS and check that all
 564  *                            journals are clean
 565  * @sdp: the file system
 566  * @state: the state to put the transaction lock into
 567  * @t_gh: the hold on the transaction lock
 568  *
 569  * Returns: errno
 570  */
 571
 572 static int gfs2_lock_fs_check_clean(struct gfs2_sbd *sdp,
 573                                     struct gfs2_holder *t_gh)
 574 {
 575         struct gfs2_inode *ip;
 576         struct gfs2_holder ji_gh;
 577         struct gfs2_jdesc *jd;
 578         struct lfcc *lfcc;
 579         LIST_HEAD(list);
 580         struct gfs2_log_header_host lh;
 581         int error;
 582
 583         error = gfs2_jindex_hold(sdp, &ji_gh);
 584         if (error)
 585                 return error;
 586
 587         list_for_each_entry(jd, &sdp->sd_jindex_list, jd_list) {
 588                 lfcc = kmalloc(sizeof(struct lfcc), GFP_KERNEL);
 589                 if (!lfcc) {
 590                         error = -ENOMEM;
 591                         goto out;
 592                 }
 593                 ip = GFS2_I(jd->jd_inode);
 594                 error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &lfcc->gh);
 595                 if (error) {
 596                         kfree(lfcc);
 597                         goto out;
 598                 }
 599                 list_add(&lfcc->list, &list);
 600         }
 601
 602         error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_DEFERRED,
 603                                    GL_NOCACHE, t_gh);
 604
 605         list_for_each_entry(jd, &sdp->sd_jindex_list, jd_list) {
 606                 error = gfs2_jdesc_check(jd);
 607                 if (error)
 608                         break;
 609                 error = gfs2_find_jhead(jd, &lh);
 610                 if (error)
 611                         break;
 612                 if (!(lh.lh_flags & GFS2_LOG_HEAD_UNMOUNT)) {
 613                         error = -EBUSY;
 614                         break;
 615                 }
 616         }
 617
 618         if (error)
 619                 gfs2_glock_dq_uninit(t_gh);
 620
 621 out:
 622         while (!list_empty(&list)) {
 623                 lfcc = list_entry(list.next, struct lfcc, list);
 624                 list_del(&lfcc->list);
 625                 gfs2_glock_dq_uninit(&lfcc->gh);
 626                 kfree(lfcc);
 627         }
 628         gfs2_glock_dq_uninit(&ji_gh);
 629         return error;
 630 }
 631
 632 /**
 633  * gfs2_freeze_fs - freezes the file system
 634  * @sdp: the file system
 635  *
 636  * This function flushes data and meta data for all machines by
 637  * aquiring the transaction log exclusively.  All journals are
 638  * ensured to be in a clean state as well.
 639  *
 640  * Returns: errno
 641  */
 642
 643 int gfs2_freeze_fs(struct gfs2_sbd *sdp)
 644 {
 645         int error = 0;
 646
 647         mutex_lock(&sdp->sd_freeze_lock);
 648
 649         if (!sdp->sd_freeze_count++) {
 650                 error = gfs2_lock_fs_check_clean(sdp, &sdp->sd_freeze_gh);
 651                 if (error)
 652                         sdp->sd_freeze_count--;
 653         }
 654
 655         mutex_unlock(&sdp->sd_freeze_lock);
 656
 657         return error;
 658 }
 659
 660 /**
 661  * gfs2_unfreeze_fs - unfreezes the file system
 662  * @sdp: the file system
 663  *
 664  * This function allows the file system to proceed by unlocking
 665  * the exclusively held transaction lock.  Other GFS2 nodes are
 666  * now free to acquire the lock shared and go on with their lives.
 667  *
 668  */
 669
 670 void gfs2_unfreeze_fs(struct gfs2_sbd *sdp)
 671 {
 672         mutex_lock(&sdp->sd_freeze_lock);
 673
 674         if (sdp->sd_freeze_count && !--sdp->sd_freeze_count)
 675                 gfs2_glock_dq_uninit(&sdp->sd_freeze_gh);
 676
 677         mutex_unlock(&sdp->sd_freeze_lock);
 678 }
 679