fs/xfs/xfs_vfsops.c

   1 /*
   2  * Copyright (c) 2000-2005 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #include "xfs.h"
  19 #include "xfs_fs.h"
  20 #include "xfs_types.h"
  21 #include "xfs_bit.h"
  22 #include "xfs_log.h"
  23 #include "xfs_inum.h"
  24 #include "xfs_trans.h"
  25 #include "xfs_sb.h"
  26 #include "xfs_ag.h"
  27 #include "xfs_dir2.h"
  28 #include "xfs_dmapi.h"
  29 #include "xfs_mount.h"
  30 #include "xfs_da_btree.h"
  31 #include "xfs_bmap_btree.h"
  32 #include "xfs_ialloc_btree.h"
  33 #include "xfs_alloc_btree.h"
  34 #include "xfs_dir2_sf.h"
  35 #include "xfs_attr_sf.h"
  36 #include "xfs_dinode.h"
  37 #include "xfs_inode.h"
  38 #include "xfs_inode_item.h"
  39 #include "xfs_btree.h"
  40 #include "xfs_alloc.h"
  41 #include "xfs_ialloc.h"
  42 #include "xfs_quota.h"
  43 #include "xfs_error.h"
  44 #include "xfs_bmap.h"
  45 #include "xfs_rw.h"
  46 #include "xfs_buf_item.h"
  47 #include "xfs_log_priv.h"
  48 #include "xfs_dir2_trace.h"
  49 #include "xfs_extfree_item.h"
  50 #include "xfs_acl.h"
  51 #include "xfs_attr.h"
  52 #include "xfs_clnt.h"
  53 #include "xfs_mru_cache.h"
  54 #include "xfs_filestream.h"
  55 #include "xfs_fsops.h"
  56 #include "xfs_vnodeops.h"
  57 #include "xfs_vfsops.h"
  58 #include "xfs_utils.h"
  59
  60
  61 STATIC void
  62 xfs_quiesce_fs(
  63         xfs_mount_t             *mp)
  64 {
  65         int                     count = 0, pincount;
  66
  67         xfs_flush_buftarg(mp->m_ddev_targp, 0);
  68         xfs_finish_reclaim_all(mp, 0);
  69
  70         /* This loop must run at least twice.
  71          * The first instance of the loop will flush
  72          * most meta data but that will generate more
  73          * meta data (typically directory updates).
  74          * Which then must be flushed and logged before
  75          * we can write the unmount record.
  76          */
  77         do {
  78                 xfs_syncsub(mp, SYNC_INODE_QUIESCE, NULL);
  79                 pincount = xfs_flush_buftarg(mp->m_ddev_targp, 1);
  80                 if (!pincount) {
  81                         delay(50);
  82                         count++;
  83                 }
  84         } while (count < 2);
  85 }
  86
  87 /*
  88  * Second stage of a quiesce. The data is already synced, now we have to take
  89  * care of the metadata. New transactions are already blocked, so we need to
  90  * wait for any remaining transactions to drain out before proceding.
  91  */
  92 void
  93 xfs_attr_quiesce(
  94         xfs_mount_t     *mp)
  95 {
  96         int     error = 0;
  97
  98         /* wait for all modifications to complete */
  99         while (atomic_read(&mp->m_active_trans) > 0)
 100                 delay(100);
 101
 102         /* flush inodes and push all remaining buffers out to disk */
 103         xfs_quiesce_fs(mp);
 104
 105         ASSERT_ALWAYS(atomic_read(&mp->m_active_trans) == 0);
 106
 107         /* Push the superblock and write an unmount record */
 108         error = xfs_log_sbcount(mp, 1);
 109         if (error)
 110                 xfs_fs_cmn_err(CE_WARN, mp,
 111                                 "xfs_attr_quiesce: failed to log sb changes. "
 112                                 "Frozen image may not be consistent.");
 113         xfs_log_unmount_write(mp);
 114         xfs_unmountfs_writesb(mp);
 115 }
 116
 117 /*
 118  * xfs_unmount_flush implements a set of flush operation on special
 119  * inodes, which are needed as a separate set of operations so that
 120  * they can be called as part of relocation process.
 121  */
 122 int
 123 xfs_unmount_flush(
 124         xfs_mount_t     *mp,            /* Mount structure we are getting
 125                                            rid of. */
 126         int             relocation)     /* Called from vfs relocation. */
 127 {
 128         xfs_inode_t     *rip = mp->m_rootip;
 129         xfs_inode_t     *rbmip;
 130         xfs_inode_t     *rsumip = NULL;
 131         bhv_vnode_t     *rvp = XFS_ITOV(rip);
 132         int             error;
 133
 134         xfs_ilock(rip, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 135         xfs_iflock(rip);
 136
 137         /*
 138          * Flush out the real time inodes.
 139          */
 140         if ((rbmip = mp->m_rbmip) != NULL) {
 141                 xfs_ilock(rbmip, XFS_ILOCK_EXCL);
 142                 xfs_iflock(rbmip);
 143                 error = xfs_iflush(rbmip, XFS_IFLUSH_SYNC);
 144                 xfs_iunlock(rbmip, XFS_ILOCK_EXCL);
 145
 146                 if (error == EFSCORRUPTED)
 147                         goto fscorrupt_out;
 148
 149                 ASSERT(vn_count(XFS_ITOV(rbmip)) == 1);
 150
 151                 rsumip = mp->m_rsumip;
 152                 xfs_ilock(rsumip, XFS_ILOCK_EXCL);
 153                 xfs_iflock(rsumip);
 154                 error = xfs_iflush(rsumip, XFS_IFLUSH_SYNC);
 155                 xfs_iunlock(rsumip, XFS_ILOCK_EXCL);
 156
 157                 if (error == EFSCORRUPTED)
 158                         goto fscorrupt_out;
 159
 160                 ASSERT(vn_count(XFS_ITOV(rsumip)) == 1);
 161         }
 162
 163         /*
 164          * Synchronously flush root inode to disk
 165          */
 166         error = xfs_iflush(rip, XFS_IFLUSH_SYNC);
 167         if (error == EFSCORRUPTED)
 168                 goto fscorrupt_out2;
 169
 170         if (vn_count(rvp) != 1 && !relocation) {
 171                 xfs_iunlock(rip, XFS_ILOCK_EXCL);
 172                 return XFS_ERROR(EBUSY);
 173         }
 174
 175         /*
 176          * Release dquot that rootinode, rbmino and rsumino might be holding,
 177          * flush and purge the quota inodes.
 178          */
 179         error = XFS_QM_UNMOUNT(mp);
 180         if (error == EFSCORRUPTED)
 181                 goto fscorrupt_out2;
 182
 183         if (rbmip) {
 184                 IRELE(rbmip);
 185                 IRELE(rsumip);
 186         }
 187
 188         xfs_iunlock(rip, XFS_ILOCK_EXCL);
 189         return 0;
 190
 191 fscorrupt_out:
 192         xfs_ifunlock(rip);
 193
 194 fscorrupt_out2:
 195         xfs_iunlock(rip, XFS_ILOCK_EXCL);
 196
 197         return XFS_ERROR(EFSCORRUPTED);
 198 }
 199
 200 /*
 201  * xfs_sync flushes any pending I/O to file system vfsp.
 202  *
 203  * This routine is called by vfs_sync() to make sure that things make it
 204  * out to disk eventually, on sync() system calls to flush out everything,
 205  * and when the file system is unmounted.  For the vfs_sync() case, all
 206  * we really need to do is sync out the log to make all of our meta-data
 207  * updates permanent (except for timestamps).  For calls from pflushd(),
 208  * dirty pages are kept moving by calling pdflush() on the inodes
 209  * containing them.  We also flush the inodes that we can lock without
 210  * sleeping and the superblock if we can lock it without sleeping from
 211  * vfs_sync() so that items at the tail of the log are always moving out.
 212  *
 213  * Flags:
 214  *      SYNC_BDFLUSH - We're being called from vfs_sync() so we don't want
 215  *                     to sleep if we can help it.  All we really need
 216  *                     to do is ensure that the log is synced at least
 217  *                     periodically.  We also push the inodes and
 218  *                     superblock if we can lock them without sleeping
 219  *                      and they are not pinned.
 220  *      SYNC_ATTR    - We need to flush the inodes.  If SYNC_BDFLUSH is not
 221  *                     set, then we really want to lock each inode and flush
 222  *                     it.
 223  *      SYNC_WAIT    - All the flushes that take place in this call should
 224  *                     be synchronous.
 225  *      SYNC_DELWRI  - This tells us to push dirty pages associated with
 226  *                     inodes.  SYNC_WAIT and SYNC_BDFLUSH are used to
 227  *                     determine if they should be flushed sync, async, or
 228  *                     delwri.
 229  *      SYNC_CLOSE   - This flag is passed when the system is being
 230  *                     unmounted.  We should sync and invalidate everything.
 231  *      SYNC_FSDATA  - This indicates that the caller would like to make
 232  *                     sure the superblock is safe on disk.  We can ensure
 233  *                     this by simply making sure the log gets flushed
 234  *                     if SYNC_BDFLUSH is set, and by actually writing it
 235  *                     out otherwise.
 236  *      SYNC_IOWAIT  - The caller wants us to wait for all data I/O to complete
 237  *                     before we return (including direct I/O). Forms the drain
 238  *                     side of the write barrier needed to safely quiesce the
 239  *                     filesystem.
 240  *
 241  */
 242 int
 243 xfs_sync(
 244         xfs_mount_t     *mp,
 245         int             flags)
 246 {
 247         int             error;
 248
 249         /*
 250          * Get the Quota Manager to flush the dquots.
 251          *
 252          * If XFS quota support is not enabled or this filesystem
 253          * instance does not use quotas XFS_QM_DQSYNC will always
 254          * return zero.
 255          */
 256         error = XFS_QM_DQSYNC(mp, flags);
 257         if (error) {
 258                 /*
 259                  * If we got an IO error, we will be shutting down.
 260                  * So, there's nothing more for us to do here.
 261                  */
 262                 ASSERT(error != EIO || XFS_FORCED_SHUTDOWN(mp));
 263                 if (XFS_FORCED_SHUTDOWN(mp))
 264                         return XFS_ERROR(error);
 265         }
 266
 267         if (flags & SYNC_IOWAIT)
 268                 xfs_filestream_flush(mp);
 269
 270         return xfs_syncsub(mp, flags, NULL);
 271 }
 272
 273 /*
 274  * xfs sync routine for internal use
 275  *
 276  * This routine supports all of the flags defined for the generic vfs_sync
 277  * interface as explained above under xfs_sync.
 278  *
 279  */
 280 int
 281 xfs_sync_inodes(
 282         xfs_mount_t     *mp,
 283         int             flags,
 284         int             *bypassed)
 285 {
 286         xfs_inode_t     *ip = NULL;
 287         bhv_vnode_t     *vp = NULL;
 288         int             error;
 289         int             last_error;
 290         uint64_t        fflag;
 291         uint            lock_flags;
 292         uint            base_lock_flags;
 293         boolean_t       mount_locked;
 294         boolean_t       vnode_refed;
 295         int             preempt;
 296         xfs_iptr_t      *ipointer;
 297 #ifdef DEBUG
 298         boolean_t       ipointer_in = B_FALSE;
 299
 300 #define IPOINTER_SET    ipointer_in = B_TRUE
 301 #define IPOINTER_CLR    ipointer_in = B_FALSE
 302 #else
 303 #define IPOINTER_SET
 304 #define IPOINTER_CLR
 305 #endif
 306
 307
 308 /* Insert a marker record into the inode list after inode ip. The list
 309  * must be locked when this is called. After the call the list will no
 310  * longer be locked.
 311  */
 312 #define IPOINTER_INSERT(ip, mp) { \
 313                 ASSERT(ipointer_in == B_FALSE); \
 314                 ipointer->ip_mnext = ip->i_mnext; \
 315                 ipointer->ip_mprev = ip; \
 316                 ip->i_mnext = (xfs_inode_t *)ipointer; \
 317                 ipointer->ip_mnext->i_mprev = (xfs_inode_t *)ipointer; \
 318                 preempt = 0; \
 319                 XFS_MOUNT_IUNLOCK(mp); \
 320                 mount_locked = B_FALSE; \
 321                 IPOINTER_SET; \
 322         }
 323
 324 /* Remove the marker from the inode list. If the marker was the only item
 325  * in the list then there are no remaining inodes and we should zero out
 326  * the whole list. If we are the current head of the list then move the head
 327  * past us.
 328  */
 329 #define IPOINTER_REMOVE(ip, mp) { \
 330                 ASSERT(ipointer_in == B_TRUE); \
 331                 if (ipointer->ip_mnext != (xfs_inode_t *)ipointer) { \
 332                         ip = ipointer->ip_mnext; \
 333                         ip->i_mprev = ipointer->ip_mprev; \
 334                         ipointer->ip_mprev->i_mnext = ip; \
 335                         if (mp->m_inodes == (xfs_inode_t *)ipointer) { \
 336                                 mp->m_inodes = ip; \
 337                         } \
 338                 } else { \
 339                         ASSERT(mp->m_inodes == (xfs_inode_t *)ipointer); \
 340                         mp->m_inodes = NULL; \
 341                         ip = NULL; \
 342                 } \
 343                 IPOINTER_CLR; \
 344         }
 345
 346 #define XFS_PREEMPT_MASK        0x7f
 347
 348         ASSERT(!(flags & SYNC_BDFLUSH));
 349
 350         if (bypassed)
 351                 *bypassed = 0;
 352         if (mp->m_flags & XFS_MOUNT_RDONLY)
 353                 return 0;
 354         error = 0;
 355         last_error = 0;
 356         preempt = 0;
 357
 358         /* Allocate a reference marker */
 359         ipointer = (xfs_iptr_t *)kmem_zalloc(sizeof(xfs_iptr_t), KM_SLEEP);
 360
 361         fflag = XFS_B_ASYNC;            /* default is don't wait */
 362         if (flags & SYNC_DELWRI)
 363                 fflag = XFS_B_DELWRI;
 364         if (flags & SYNC_WAIT)
 365                 fflag = 0;              /* synchronous overrides all */
 366
 367         base_lock_flags = XFS_ILOCK_SHARED;
 368         if (flags & (SYNC_DELWRI | SYNC_CLOSE)) {
 369                 /*
 370                  * We need the I/O lock if we're going to call any of
 371                  * the flush/inval routines.
 372                  */
 373                 base_lock_flags |= XFS_IOLOCK_SHARED;
 374         }
 375
 376         XFS_MOUNT_ILOCK(mp);
 377
 378         ip = mp->m_inodes;
 379
 380         mount_locked = B_TRUE;
 381         vnode_refed  = B_FALSE;
 382
 383         IPOINTER_CLR;
 384
 385         do {
 386                 ASSERT(ipointer_in == B_FALSE);
 387                 ASSERT(vnode_refed == B_FALSE);
 388
 389                 lock_flags = base_lock_flags;
 390
 391                 /*
 392                  * There were no inodes in the list, just break out
 393                  * of the loop.
 394                  */
 395                 if (ip == NULL) {
 396                         break;
 397                 }
 398
 399                 /*
 400                  * We found another sync thread marker - skip it
 401                  */
 402                 if (ip->i_mount == NULL) {
 403                         ip = ip->i_mnext;
 404                         continue;
 405                 }
 406
 407                 vp = XFS_ITOV_NULL(ip);
 408
 409                 /*
 410                  * If the vnode is gone then this is being torn down,
 411                  * call reclaim if it is flushed, else let regular flush
 412                  * code deal with it later in the loop.
 413                  */
 414
 415                 if (vp == NULL) {
 416                         /* Skip ones already in reclaim */
 417                         if (ip->i_flags & XFS_IRECLAIM) {
 418                                 ip = ip->i_mnext;
 419                                 continue;
 420                         }
 421                         if (xfs_ilock_nowait(ip, XFS_ILOCK_EXCL) == 0) {
 422                                 ip = ip->i_mnext;
 423                         } else if ((xfs_ipincount(ip) == 0) &&
 424                                     xfs_iflock_nowait(ip)) {
 425                                 IPOINTER_INSERT(ip, mp);
 426
 427                                 xfs_finish_reclaim(ip, 1,
 428                                                 XFS_IFLUSH_DELWRI_ELSE_ASYNC);
 429
 430                                 XFS_MOUNT_ILOCK(mp);
 431                                 mount_locked = B_TRUE;
 432                                 IPOINTER_REMOVE(ip, mp);
 433                         } else {
 434                                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 435                                 ip = ip->i_mnext;
 436                         }
 437                         continue;
 438                 }
 439
 440                 if (VN_BAD(vp)) {
 441                         ip = ip->i_mnext;
 442                         continue;
 443                 }
 444
 445                 if (XFS_FORCED_SHUTDOWN(mp) && !(flags & SYNC_CLOSE)) {
 446                         XFS_MOUNT_IUNLOCK(mp);
 447                         kmem_free(ipointer);
 448                         return 0;
 449                 }
 450
 451                 /*
 452                  * Try to lock without sleeping.  We're out of order with
 453                  * the inode list lock here, so if we fail we need to drop
 454                  * the mount lock and try again.  If we're called from
 455                  * bdflush() here, then don't bother.
 456                  *
 457                  * The inode lock here actually coordinates with the
 458                  * almost spurious inode lock in xfs_ireclaim() to prevent
 459                  * the vnode we handle here without a reference from
 460                  * being freed while we reference it.  If we lock the inode
 461                  * while it's on the mount list here, then the spurious inode
 462                  * lock in xfs_ireclaim() after the inode is pulled from
 463                  * the mount list will sleep until we release it here.
 464                  * This keeps the vnode from being freed while we reference
 465                  * it.
 466                  */
 467                 if (xfs_ilock_nowait(ip, lock_flags) == 0) {
 468                         if (vp == NULL) {
 469                                 ip = ip->i_mnext;
 470                                 continue;
 471                         }
 472
 473                         vp = vn_grab(vp);
 474                         if (vp == NULL) {
 475                                 ip = ip->i_mnext;
 476                                 continue;
 477                         }
 478
 479                         IPOINTER_INSERT(ip, mp);
 480                         xfs_ilock(ip, lock_flags);
 481
 482                         ASSERT(vp == XFS_ITOV(ip));
 483                         ASSERT(ip->i_mount == mp);
 484
 485                         vnode_refed = B_TRUE;
 486                 }
 487
 488                 /* From here on in the loop we may have a marker record
 489                  * in the inode list.
 490                  */
 491
 492                 /*
 493                  * If we have to flush data or wait for I/O completion
 494                  * we need to drop the ilock that we currently hold.
 495                  * If we need to drop the lock, insert a marker if we
 496                  * have not already done so.
 497                  */
 498                 if ((flags & (SYNC_CLOSE|SYNC_IOWAIT)) ||
 499                     ((flags & SYNC_DELWRI) && VN_DIRTY(vp))) {
 500                         if (mount_locked) {
 501                                 IPOINTER_INSERT(ip, mp);
 502                         }
 503                         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 504
 505                         if (flags & SYNC_CLOSE) {
 506                                 /* Shutdown case. Flush and invalidate. */
 507                                 if (XFS_FORCED_SHUTDOWN(mp))
 508                                         xfs_tosspages(ip, 0, -1,
 509                                                              FI_REMAPF);
 510                                 else
 511                                         error = xfs_flushinval_pages(ip,
 512                                                         0, -1, FI_REMAPF);
 513                         } else if ((flags & SYNC_DELWRI) && VN_DIRTY(vp)) {
 514                                 error = xfs_flush_pages(ip, 0,
 515                                                         -1, fflag, FI_NONE);
 516                         }
 517
 518                         /*
 519                          * When freezing, we need to wait ensure all I/O (including direct
 520                          * I/O) is complete to ensure no further data modification can take
 521                          * place after this point
 522                          */
 523                         if (flags & SYNC_IOWAIT)
 524                                 vn_iowait(ip);
 525
 526                         xfs_ilock(ip, XFS_ILOCK_SHARED);
 527                 }
 528
 529                 if ((flags & SYNC_ATTR) &&
 530                     (ip->i_update_core ||
 531                      (ip->i_itemp && ip->i_itemp->ili_format.ilf_fields))) {
 532                         if (mount_locked)
 533                                 IPOINTER_INSERT(ip, mp);
 534
 535                         if (flags & SYNC_WAIT) {
 536                                 xfs_iflock(ip);
 537                                 error = xfs_iflush(ip, XFS_IFLUSH_SYNC);
 538
 539                         /*
 540                          * If we can't acquire the flush lock, then the inode
 541                          * is already being flushed so don't bother waiting.
 542                          *
 543                          * If we can lock it then do a delwri flush so we can
 544                          * combine multiple inode flushes in each disk write.
 545                          */
 546                         } else if (xfs_iflock_nowait(ip)) {
 547                                 error = xfs_iflush(ip, XFS_IFLUSH_DELWRI);
 548                         } else if (bypassed) {
 549                                 (*bypassed)++;
 550                         }
 551                 }
 552
 553                 if (lock_flags != 0) {
 554                         xfs_iunlock(ip, lock_flags);
 555                 }
 556
 557                 if (vnode_refed) {
 558                         /*
 559                          * If we had to take a reference on the vnode
 560                          * above, then wait until after we've unlocked
 561                          * the inode to release the reference.  This is
 562                          * because we can be already holding the inode
 563                          * lock when IRELE() calls xfs_inactive().
 564                          *
 565                          * Make sure to drop the mount lock before calling
 566                          * IRELE() so that we don't trip over ourselves if
 567                          * we have to go for the mount lock again in the
 568                          * inactive code.
 569                          */
 570                         if (mount_locked) {
 571                                 IPOINTER_INSERT(ip, mp);
 572                         }
 573
 574                         IRELE(ip);
 575
 576                         vnode_refed = B_FALSE;
 577                 }
 578
 579                 if (error) {
 580                         last_error = error;
 581                 }
 582
 583                 /*
 584                  * bail out if the filesystem is corrupted.
 585                  */
 586                 if (error == EFSCORRUPTED)  {
 587                         if (!mount_locked) {
 588                                 XFS_MOUNT_ILOCK(mp);
 589                                 IPOINTER_REMOVE(ip, mp);
 590                         }
 591                         XFS_MOUNT_IUNLOCK(mp);
 592                         ASSERT(ipointer_in == B_FALSE);
 593                         kmem_free(ipointer);
 594                         return XFS_ERROR(error);
 595                 }
 596
 597                 /* Let other threads have a chance at the mount lock
 598                  * if we have looped many times without dropping the
 599                  * lock.
 600                  */
 601                 if ((++preempt & XFS_PREEMPT_MASK) == 0) {
 602                         if (mount_locked) {
 603                                 IPOINTER_INSERT(ip, mp);
 604                         }
 605                 }
 606
 607                 if (mount_locked == B_FALSE) {
 608                         XFS_MOUNT_ILOCK(mp);
 609                         mount_locked = B_TRUE;
 610                         IPOINTER_REMOVE(ip, mp);
 611                         continue;
 612                 }
 613
 614                 ASSERT(ipointer_in == B_FALSE);
 615                 ip = ip->i_mnext;
 616
 617         } while (ip != mp->m_inodes);
 618
 619         XFS_MOUNT_IUNLOCK(mp);
 620
 621         ASSERT(ipointer_in == B_FALSE);
 622
 623         kmem_free(ipointer);
 624         return XFS_ERROR(last_error);
 625 }
 626
 627 /*
 628  * xfs sync routine for internal use
 629  *
 630  * This routine supports all of the flags defined for the generic vfs_sync
 631  * interface as explained above under xfs_sync.
 632  *
 633  */
 634 int
 635 xfs_syncsub(
 636         xfs_mount_t     *mp,
 637         int             flags,
 638         int             *bypassed)
 639 {
 640         int             error = 0;
 641         int             last_error = 0;
 642         uint            log_flags = XFS_LOG_FORCE;
 643         xfs_buf_t       *bp;
 644         xfs_buf_log_item_t      *bip;
 645
 646         /*
 647          * Sync out the log.  This ensures that the log is periodically
 648          * flushed even if there is not enough activity to fill it up.
 649          */
 650         if (flags & SYNC_WAIT)
 651                 log_flags |= XFS_LOG_SYNC;
 652
 653         xfs_log_force(mp, (xfs_lsn_t)0, log_flags);
 654
 655         if (flags & (SYNC_ATTR|SYNC_DELWRI)) {
 656                 if (flags & SYNC_BDFLUSH)
 657                         xfs_finish_reclaim_all(mp, 1);
 658                 else
 659                         error = xfs_sync_inodes(mp, flags, bypassed);
 660         }
 661
 662         /*
 663          * Flushing out dirty data above probably generated more
 664          * log activity, so if this isn't vfs_sync() then flush
 665          * the log again.
 666          */
 667         if (flags & SYNC_DELWRI) {
 668                 xfs_log_force(mp, (xfs_lsn_t)0, log_flags);
 669         }
 670
 671         if (flags & SYNC_FSDATA) {
 672                 /*
 673                  * If this is vfs_sync() then only sync the superblock
 674                  * if we can lock it without sleeping and it is not pinned.
 675                  */
 676                 if (flags & SYNC_BDFLUSH) {
 677                         bp = xfs_getsb(mp, XFS_BUF_TRYLOCK);
 678                         if (bp != NULL) {
 679                                 bip = XFS_BUF_FSPRIVATE(bp,xfs_buf_log_item_t*);
 680                                 if ((bip != NULL) &&
 681                                     xfs_buf_item_dirty(bip)) {
 682                                         if (!(XFS_BUF_ISPINNED(bp))) {
 683                                                 XFS_BUF_ASYNC(bp);
 684                                                 error = xfs_bwrite(mp, bp);
 685                                         } else {
 686                                                 xfs_buf_relse(bp);
 687                                         }
 688                                 } else {
 689                                         xfs_buf_relse(bp);
 690                                 }
 691                         }
 692                 } else {
 693                         bp = xfs_getsb(mp, 0);
 694                         /*
 695                          * If the buffer is pinned then push on the log so
 696                          * we won't get stuck waiting in the write for
 697                          * someone, maybe ourselves, to flush the log.
 698                          * Even though we just pushed the log above, we
 699                          * did not have the superblock buffer locked at
 700                          * that point so it can become pinned in between
 701                          * there and here.
 702                          */
 703                         if (XFS_BUF_ISPINNED(bp))
 704                                 xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
 705                         if (flags & SYNC_WAIT)
 706                                 XFS_BUF_UNASYNC(bp);
 707                         else
 708                                 XFS_BUF_ASYNC(bp);
 709                         error = xfs_bwrite(mp, bp);
 710                 }
 711                 if (error) {
 712                         last_error = error;
 713                 }
 714         }
 715
 716         /*
 717          * Now check to see if the log needs a "dummy" transaction.
 718          */
 719         if (!(flags & SYNC_REMOUNT) && xfs_log_need_covered(mp)) {
 720                 xfs_trans_t *tp;
 721                 xfs_inode_t *ip;
 722
 723                 /*
 724                  * Put a dummy transaction in the log to tell
 725                  * recovery that all others are OK.
 726                  */
 727                 tp = xfs_trans_alloc(mp, XFS_TRANS_DUMMY1);
 728                 if ((error = xfs_trans_reserve(tp, 0,
 729                                 XFS_ICHANGE_LOG_RES(mp),
 730                                 0, 0, 0)))  {
 731                         xfs_trans_cancel(tp, 0);
 732                         return error;
 733                 }
 734
 735                 ip = mp->m_rootip;
 736                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 737
 738                 xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 739                 xfs_trans_ihold(tp, ip);
 740                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 741                 error = xfs_trans_commit(tp, 0);
 742                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 743                 xfs_log_force(mp, (xfs_lsn_t)0, log_flags);
 744         }
 745
 746         /*
 747          * When shutting down, we need to insure that the AIL is pushed
 748          * to disk or the filesystem can appear corrupt from the PROM.
 749          */
 750         if ((flags & (SYNC_CLOSE|SYNC_WAIT)) == (SYNC_CLOSE|SYNC_WAIT)) {
 751                 XFS_bflush(mp->m_ddev_targp);
 752                 if (mp->m_rtdev_targp) {
 753                         XFS_bflush(mp->m_rtdev_targp);
 754                 }
 755         }
 756
 757         return XFS_ERROR(last_error);
 758 }