git.oblomov.eu Git - linux-2.6/blob - 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         int             error;
 132
 133         xfs_ilock(rip, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 134         xfs_iflock(rip);
 135
 136         /*
 137          * Flush out the real time inodes.
 138          */
 139         if ((rbmip = mp->m_rbmip) != NULL) {
 140                 xfs_ilock(rbmip, XFS_ILOCK_EXCL);
 141                 xfs_iflock(rbmip);
 142                 error = xfs_iflush(rbmip, XFS_IFLUSH_SYNC);
 143                 xfs_iunlock(rbmip, XFS_ILOCK_EXCL);
 144
 145                 if (error == EFSCORRUPTED)
 146                         goto fscorrupt_out;
 147
 148                 ASSERT(vn_count(VFS_I(rbmip)) == 1);
 149
 150                 rsumip = mp->m_rsumip;
 151                 xfs_ilock(rsumip, XFS_ILOCK_EXCL);
 152                 xfs_iflock(rsumip);
 153                 error = xfs_iflush(rsumip, XFS_IFLUSH_SYNC);
 154                 xfs_iunlock(rsumip, XFS_ILOCK_EXCL);
 155
 156                 if (error == EFSCORRUPTED)
 157                         goto fscorrupt_out;
 158
 159                 ASSERT(vn_count(VFS_I(rsumip)) == 1);
 160         }
 161
 162         /*
 163          * Synchronously flush root inode to disk
 164          */
 165         error = xfs_iflush(rip, XFS_IFLUSH_SYNC);
 166         if (error == EFSCORRUPTED)
 167                 goto fscorrupt_out2;
 168
 169         if (vn_count(VFS_I(rip)) != 1 && !relocation) {
 170                 xfs_iunlock(rip, XFS_ILOCK_EXCL);
 171                 return XFS_ERROR(EBUSY);
 172         }
 173
 174         /*
 175          * Release dquot that rootinode, rbmino and rsumino might be holding,
 176          * flush and purge the quota inodes.
 177          */
 178         error = XFS_QM_UNMOUNT(mp);
 179         if (error == EFSCORRUPTED)
 180                 goto fscorrupt_out2;
 181
 182         if (rbmip) {
 183                 IRELE(rbmip);
 184                 IRELE(rsumip);
 185         }
 186
 187         xfs_iunlock(rip, XFS_ILOCK_EXCL);
 188         return 0;
 189
 190 fscorrupt_out:
 191         xfs_ifunlock(rip);
 192
 193 fscorrupt_out2:
 194         xfs_iunlock(rip, XFS_ILOCK_EXCL);
 195
 196         return XFS_ERROR(EFSCORRUPTED);
 197 }
 198
 199 /*
 200  * xfs_sync flushes any pending I/O to file system vfsp.
 201  *
 202  * This routine is called by vfs_sync() to make sure that things make it
 203  * out to disk eventually, on sync() system calls to flush out everything,
 204  * and when the file system is unmounted.  For the vfs_sync() case, all
 205  * we really need to do is sync out the log to make all of our meta-data
 206  * updates permanent (except for timestamps).  For calls from pflushd(),
 207  * dirty pages are kept moving by calling pdflush() on the inodes
 208  * containing them.  We also flush the inodes that we can lock without
 209  * sleeping and the superblock if we can lock it without sleeping from
 210  * vfs_sync() so that items at the tail of the log are always moving out.
 211  *
 212  * Flags:
 213  *      SYNC_BDFLUSH - We're being called from vfs_sync() so we don't want
 214  *                     to sleep if we can help it.  All we really need
 215  *                     to do is ensure that the log is synced at least
 216  *                     periodically.  We also push the inodes and
 217  *                     superblock if we can lock them without sleeping
 218  *                      and they are not pinned.
 219  *      SYNC_ATTR    - We need to flush the inodes.  If SYNC_BDFLUSH is not
 220  *                     set, then we really want to lock each inode and flush
 221  *                     it.
 222  *      SYNC_WAIT    - All the flushes that take place in this call should
 223  *                     be synchronous.
 224  *      SYNC_DELWRI  - This tells us to push dirty pages associated with
 225  *                     inodes.  SYNC_WAIT and SYNC_BDFLUSH are used to
 226  *                     determine if they should be flushed sync, async, or
 227  *                     delwri.
 228  *      SYNC_CLOSE   - This flag is passed when the system is being
 229  *                     unmounted.  We should sync and invalidate everything.
 230  *      SYNC_FSDATA  - This indicates that the caller would like to make
 231  *                     sure the superblock is safe on disk.  We can ensure
 232  *                     this by simply making sure the log gets flushed
 233  *                     if SYNC_BDFLUSH is set, and by actually writing it
 234  *                     out otherwise.
 235  *      SYNC_IOWAIT  - The caller wants us to wait for all data I/O to complete
 236  *                     before we return (including direct I/O). Forms the drain
 237  *                     side of the write barrier needed to safely quiesce the
 238  *                     filesystem.
 239  *
 240  */
 241 int
 242 xfs_sync(
 243         xfs_mount_t     *mp,
 244         int             flags)
 245 {
 246         int             error;
 247
 248         /*
 249          * Get the Quota Manager to flush the dquots.
 250          *
 251          * If XFS quota support is not enabled or this filesystem
 252          * instance does not use quotas XFS_QM_DQSYNC will always
 253          * return zero.
 254          */
 255         error = XFS_QM_DQSYNC(mp, flags);
 256         if (error) {
 257                 /*
 258                  * If we got an IO error, we will be shutting down.
 259                  * So, there's nothing more for us to do here.
 260                  */
 261                 ASSERT(error != EIO || XFS_FORCED_SHUTDOWN(mp));
 262                 if (XFS_FORCED_SHUTDOWN(mp))
 263                         return XFS_ERROR(error);
 264         }
 265
 266         if (flags & SYNC_IOWAIT)
 267                 xfs_filestream_flush(mp);
 268
 269         return xfs_syncsub(mp, flags, NULL);
 270 }
 271
 272 /*
 273  * xfs sync routine for internal use
 274  *
 275  * This routine supports all of the flags defined for the generic vfs_sync
 276  * interface as explained above under xfs_sync.
 277  *
 278  */
 279 int
 280 xfs_sync_inodes(
 281         xfs_mount_t     *mp,
 282         int             flags,
 283         int             *bypassed)
 284 {
 285         xfs_inode_t     *ip = NULL;
 286         struct inode    *vp = NULL;
 287         int             error;
 288         int             last_error;
 289         uint64_t        fflag;
 290         uint            lock_flags;
 291         uint            base_lock_flags;
 292         boolean_t       mount_locked;
 293         boolean_t       vnode_refed;
 294         int             preempt;
 295         xfs_iptr_t      *ipointer;
 296 #ifdef DEBUG
 297         boolean_t       ipointer_in = B_FALSE;
 298
 299 #define IPOINTER_SET    ipointer_in = B_TRUE
 300 #define IPOINTER_CLR    ipointer_in = B_FALSE
 301 #else
 302 #define IPOINTER_SET
 303 #define IPOINTER_CLR
 304 #endif
 305
 306
 307 /* Insert a marker record into the inode list after inode ip. The list
 308  * must be locked when this is called. After the call the list will no
 309  * longer be locked.
 310  */
 311 #define IPOINTER_INSERT(ip, mp) { \
 312                 ASSERT(ipointer_in == B_FALSE); \
 313                 ipointer->ip_mnext = ip->i_mnext; \
 314                 ipointer->ip_mprev = ip; \
 315                 ip->i_mnext = (xfs_inode_t *)ipointer; \
 316                 ipointer->ip_mnext->i_mprev = (xfs_inode_t *)ipointer; \
 317                 preempt = 0; \
 318                 XFS_MOUNT_IUNLOCK(mp); \
 319                 mount_locked = B_FALSE; \
 320                 IPOINTER_SET; \
 321         }
 322
 323 /* Remove the marker from the inode list. If the marker was the only item
 324  * in the list then there are no remaining inodes and we should zero out
 325  * the whole list. If we are the current head of the list then move the head
 326  * past us.
 327  */
 328 #define IPOINTER_REMOVE(ip, mp) { \
 329                 ASSERT(ipointer_in == B_TRUE); \
 330                 if (ipointer->ip_mnext != (xfs_inode_t *)ipointer) { \
 331                         ip = ipointer->ip_mnext; \
 332                         ip->i_mprev = ipointer->ip_mprev; \
 333                         ipointer->ip_mprev->i_mnext = ip; \
 334                         if (mp->m_inodes == (xfs_inode_t *)ipointer) { \
 335                                 mp->m_inodes = ip; \
 336                         } \
 337                 } else { \
 338                         ASSERT(mp->m_inodes == (xfs_inode_t *)ipointer); \
 339                         mp->m_inodes = NULL; \
 340                         ip = NULL; \
 341                 } \
 342                 IPOINTER_CLR; \
 343         }
 344
 345 #define XFS_PREEMPT_MASK        0x7f
 346
 347         ASSERT(!(flags & SYNC_BDFLUSH));
 348
 349         if (bypassed)
 350                 *bypassed = 0;
 351         if (mp->m_flags & XFS_MOUNT_RDONLY)
 352                 return 0;
 353         error = 0;
 354         last_error = 0;
 355         preempt = 0;
 356
 357         /* Allocate a reference marker */
 358         ipointer = (xfs_iptr_t *)kmem_zalloc(sizeof(xfs_iptr_t), KM_SLEEP);
 359
 360         fflag = XFS_B_ASYNC;            /* default is don't wait */
 361         if (flags & SYNC_DELWRI)
 362                 fflag = XFS_B_DELWRI;
 363         if (flags & SYNC_WAIT)
 364                 fflag = 0;              /* synchronous overrides all */
 365
 366         base_lock_flags = XFS_ILOCK_SHARED;
 367         if (flags & (SYNC_DELWRI | SYNC_CLOSE)) {
 368                 /*
 369                  * We need the I/O lock if we're going to call any of
 370                  * the flush/inval routines.
 371                  */
 372                 base_lock_flags |= XFS_IOLOCK_SHARED;
 373         }
 374
 375         XFS_MOUNT_ILOCK(mp);
 376
 377         ip = mp->m_inodes;
 378
 379         mount_locked = B_TRUE;
 380         vnode_refed  = B_FALSE;
 381
 382         IPOINTER_CLR;
 383
 384         do {
 385                 ASSERT(ipointer_in == B_FALSE);
 386                 ASSERT(vnode_refed == B_FALSE);
 387
 388                 lock_flags = base_lock_flags;
 389
 390                 /*
 391                  * There were no inodes in the list, just break out
 392                  * of the loop.
 393                  */
 394                 if (ip == NULL) {
 395                         break;
 396                 }
 397
 398                 /*
 399                  * We found another sync thread marker - skip it
 400                  */
 401                 if (ip->i_mount == NULL) {
 402                         ip = ip->i_mnext;
 403                         continue;
 404                 }
 405
 406                 vp = VFS_I(ip);
 407
 408                 /*
 409                  * If the vnode is gone then this is being torn down,
 410                  * call reclaim if it is flushed, else let regular flush
 411                  * code deal with it later in the loop.
 412                  */
 413
 414                 if (vp == NULL) {
 415                         /* Skip ones already in reclaim */
 416                         if (ip->i_flags & XFS_IRECLAIM) {
 417                                 ip = ip->i_mnext;
 418                                 continue;
 419                         }
 420                         if (xfs_ilock_nowait(ip, XFS_ILOCK_EXCL) == 0) {
 421                                 ip = ip->i_mnext;
 422                         } else if ((xfs_ipincount(ip) == 0) &&
 423                                     xfs_iflock_nowait(ip)) {
 424                                 IPOINTER_INSERT(ip, mp);
 425
 426                                 xfs_finish_reclaim(ip, 1,
 427                                                 XFS_IFLUSH_DELWRI_ELSE_ASYNC);
 428
 429                                 XFS_MOUNT_ILOCK(mp);
 430                                 mount_locked = B_TRUE;
 431                                 IPOINTER_REMOVE(ip, mp);
 432                         } else {
 433                                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 434                                 ip = ip->i_mnext;
 435                         }
 436                         continue;
 437                 }
 438
 439                 if (VN_BAD(vp)) {
 440                         ip = ip->i_mnext;
 441                         continue;
 442                 }
 443
 444                 if (XFS_FORCED_SHUTDOWN(mp) && !(flags & SYNC_CLOSE)) {
 445                         XFS_MOUNT_IUNLOCK(mp);
 446                         kmem_free(ipointer);
 447                         return 0;
 448                 }
 449
 450                 /*
 451                  * Try to lock without sleeping.  We're out of order with
 452                  * the inode list lock here, so if we fail we need to drop
 453                  * the mount lock and try again.  If we're called from
 454                  * bdflush() here, then don't bother.
 455                  *
 456                  * The inode lock here actually coordinates with the
 457                  * almost spurious inode lock in xfs_ireclaim() to prevent
 458                  * the vnode we handle here without a reference from
 459                  * being freed while we reference it.  If we lock the inode
 460                  * while it's on the mount list here, then the spurious inode
 461                  * lock in xfs_ireclaim() after the inode is pulled from
 462                  * the mount list will sleep until we release it here.
 463                  * This keeps the vnode from being freed while we reference
 464                  * it.
 465                  */
 466                 if (xfs_ilock_nowait(ip, lock_flags) == 0) {
 467                         if (vp == NULL) {
 468                                 ip = ip->i_mnext;
 469                                 continue;
 470                         }
 471
 472                         vp = vn_grab(vp);
 473                         if (vp == NULL) {
 474                                 ip = ip->i_mnext;
 475                                 continue;
 476                         }
 477
 478                         IPOINTER_INSERT(ip, mp);
 479                         xfs_ilock(ip, lock_flags);
 480
 481                         ASSERT(vp == VFS_I(ip));
 482                         ASSERT(ip->i_mount == mp);
 483
 484                         vnode_refed = B_TRUE;
 485                 }
 486
 487                 /* From here on in the loop we may have a marker record
 488                  * in the inode list.
 489                  */
 490
 491                 /*
 492                  * If we have to flush data or wait for I/O completion
 493                  * we need to drop the ilock that we currently hold.
 494                  * If we need to drop the lock, insert a marker if we
 495                  * have not already done so.
 496                  */
 497                 if ((flags & (SYNC_CLOSE|SYNC_IOWAIT)) ||
 498                     ((flags & SYNC_DELWRI) && VN_DIRTY(vp))) {
 499                         if (mount_locked) {
 500                                 IPOINTER_INSERT(ip, mp);
 501                         }
 502                         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 503
 504                         if (flags & SYNC_CLOSE) {
 505                                 /* Shutdown case. Flush and invalidate. */
 506                                 if (XFS_FORCED_SHUTDOWN(mp))
 507                                         xfs_tosspages(ip, 0, -1,
 508                                                              FI_REMAPF);
 509                                 else
 510                                         error = xfs_flushinval_pages(ip,
 511                                                         0, -1, FI_REMAPF);
 512                         } else if ((flags & SYNC_DELWRI) && VN_DIRTY(vp)) {
 513                                 error = xfs_flush_pages(ip, 0,
 514                                                         -1, fflag, FI_NONE);
 515                         }
 516
 517                         /*
 518                          * When freezing, we need to wait ensure all I/O (including direct
 519                          * I/O) is complete to ensure no further data modification can take
 520                          * place after this point
 521                          */
 522                         if (flags & SYNC_IOWAIT)
 523                                 vn_iowait(ip);
 524
 525                         xfs_ilock(ip, XFS_ILOCK_SHARED);
 526                 }
 527
 528                 if ((flags & SYNC_ATTR) &&
 529                     (ip->i_update_core ||
 530                      (ip->i_itemp && ip->i_itemp->ili_format.ilf_fields))) {
 531                         if (mount_locked)
 532                                 IPOINTER_INSERT(ip, mp);
 533
 534                         if (flags & SYNC_WAIT) {
 535                                 xfs_iflock(ip);
 536                                 error = xfs_iflush(ip, XFS_IFLUSH_SYNC);
 537
 538                         /*
 539                          * If we can't acquire the flush lock, then the inode
 540                          * is already being flushed so don't bother waiting.
 541                          *
 542                          * If we can lock it then do a delwri flush so we can
 543                          * combine multiple inode flushes in each disk write.
 544                          */
 545                         } else if (xfs_iflock_nowait(ip)) {
 546                                 error = xfs_iflush(ip, XFS_IFLUSH_DELWRI);
 547                         } else if (bypassed) {
 548                                 (*bypassed)++;
 549                         }
 550                 }
 551
 552                 if (lock_flags != 0) {
 553                         xfs_iunlock(ip, lock_flags);
 554                 }
 555
 556                 if (vnode_refed) {
 557                         /*
 558                          * If we had to take a reference on the vnode
 559                          * above, then wait until after we've unlocked
 560                          * the inode to release the reference.  This is
 561                          * because we can be already holding the inode
 562                          * lock when IRELE() calls xfs_inactive().
 563                          *
 564                          * Make sure to drop the mount lock before calling
 565                          * IRELE() so that we don't trip over ourselves if
 566                          * we have to go for the mount lock again in the
 567                          * inactive code.
 568                          */
 569                         if (mount_locked) {
 570                                 IPOINTER_INSERT(ip, mp);
 571                         }
 572
 573                         IRELE(ip);
 574
 575                         vnode_refed = B_FALSE;
 576                 }
 577
 578                 if (error) {
 579                         last_error = error;
 580                 }
 581
 582                 /*
 583                  * bail out if the filesystem is corrupted.
 584                  */
 585                 if (error == EFSCORRUPTED)  {
 586                         if (!mount_locked) {
 587                                 XFS_MOUNT_ILOCK(mp);
 588                                 IPOINTER_REMOVE(ip, mp);
 589                         }
 590                         XFS_MOUNT_IUNLOCK(mp);
 591                         ASSERT(ipointer_in == B_FALSE);
 592                         kmem_free(ipointer);
 593                         return XFS_ERROR(error);
 594                 }
 595
 596                 /* Let other threads have a chance at the mount lock
 597                  * if we have looped many times without dropping the
 598                  * lock.
 599                  */
 600                 if ((++preempt & XFS_PREEMPT_MASK) == 0) {
 601                         if (mount_locked) {
 602                                 IPOINTER_INSERT(ip, mp);
 603                         }
 604                 }
 605
 606                 if (mount_locked == B_FALSE) {
 607                         XFS_MOUNT_ILOCK(mp);
 608                         mount_locked = B_TRUE;
 609                         IPOINTER_REMOVE(ip, mp);
 610                         continue;
 611                 }
 612
 613                 ASSERT(ipointer_in == B_FALSE);
 614                 ip = ip->i_mnext;
 615
 616         } while (ip != mp->m_inodes);
 617
 618         XFS_MOUNT_IUNLOCK(mp);
 619
 620         ASSERT(ipointer_in == B_FALSE);
 621
 622         kmem_free(ipointer);
 623         return XFS_ERROR(last_error);
 624 }
 625
 626 /*
 627  * xfs sync routine for internal use
 628  *
 629  * This routine supports all of the flags defined for the generic vfs_sync
 630  * interface as explained above under xfs_sync.
 631  *
 632  */
 633 int
 634 xfs_syncsub(
 635         xfs_mount_t     *mp,
 636         int             flags,
 637         int             *bypassed)
 638 {
 639         int             error = 0;
 640         int             last_error = 0;
 641         uint            log_flags = XFS_LOG_FORCE;
 642         xfs_buf_t       *bp;
 643         xfs_buf_log_item_t      *bip;
 644
 645         /*
 646          * Sync out the log.  This ensures that the log is periodically
 647          * flushed even if there is not enough activity to fill it up.
 648          */
 649         if (flags & SYNC_WAIT)
 650                 log_flags |= XFS_LOG_SYNC;
 651
 652         xfs_log_force(mp, (xfs_lsn_t)0, log_flags);
 653
 654         if (flags & (SYNC_ATTR|SYNC_DELWRI)) {
 655                 if (flags & SYNC_BDFLUSH)
 656                         xfs_finish_reclaim_all(mp, 1);
 657                 else
 658                         error = xfs_sync_inodes(mp, flags, bypassed);
 659         }
 660
 661         /*
 662          * Flushing out dirty data above probably generated more
 663          * log activity, so if this isn't vfs_sync() then flush
 664          * the log again.
 665          */
 666         if (flags & SYNC_DELWRI) {
 667                 xfs_log_force(mp, (xfs_lsn_t)0, log_flags);
 668         }
 669
 670         if (flags & SYNC_FSDATA) {
 671                 /*
 672                  * If this is vfs_sync() then only sync the superblock
 673                  * if we can lock it without sleeping and it is not pinned.
 674                  */
 675                 if (flags & SYNC_BDFLUSH) {
 676                         bp = xfs_getsb(mp, XFS_BUF_TRYLOCK);
 677                         if (bp != NULL) {
 678                                 bip = XFS_BUF_FSPRIVATE(bp,xfs_buf_log_item_t*);
 679                                 if ((bip != NULL) &&
 680                                     xfs_buf_item_dirty(bip)) {
 681                                         if (!(XFS_BUF_ISPINNED(bp))) {
 682                                                 XFS_BUF_ASYNC(bp);
 683                                                 error = xfs_bwrite(mp, bp);
 684                                         } else {
 685                                                 xfs_buf_relse(bp);
 686                                         }
 687                                 } else {
 688                                         xfs_buf_relse(bp);
 689                                 }
 690                         }
 691                 } else {
 692                         bp = xfs_getsb(mp, 0);
 693                         /*
 694                          * If the buffer is pinned then push on the log so
 695                          * we won't get stuck waiting in the write for
 696                          * someone, maybe ourselves, to flush the log.
 697                          * Even though we just pushed the log above, we
 698                          * did not have the superblock buffer locked at
 699                          * that point so it can become pinned in between
 700                          * there and here.
 701                          */
 702                         if (XFS_BUF_ISPINNED(bp))
 703                                 xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
 704                         if (flags & SYNC_WAIT)
 705                                 XFS_BUF_UNASYNC(bp);
 706                         else
 707                                 XFS_BUF_ASYNC(bp);
 708                         error = xfs_bwrite(mp, bp);
 709                 }
 710                 if (error) {
 711                         last_error = error;
 712                 }
 713         }
 714
 715         /*
 716          * Now check to see if the log needs a "dummy" transaction.
 717          */
 718         if (!(flags & SYNC_REMOUNT) && xfs_log_need_covered(mp)) {
 719                 xfs_trans_t *tp;
 720                 xfs_inode_t *ip;
 721
 722                 /*
 723                  * Put a dummy transaction in the log to tell
 724                  * recovery that all others are OK.
 725                  */
 726                 tp = xfs_trans_alloc(mp, XFS_TRANS_DUMMY1);
 727                 if ((error = xfs_trans_reserve(tp, 0,
 728                                 XFS_ICHANGE_LOG_RES(mp),
 729                                 0, 0, 0)))  {
 730                         xfs_trans_cancel(tp, 0);
 731                         return error;
 732                 }
 733
 734                 ip = mp->m_rootip;
 735                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 736
 737                 xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 738                 xfs_trans_ihold(tp, ip);
 739                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 740                 error = xfs_trans_commit(tp, 0);
 741                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 742                 xfs_log_force(mp, (xfs_lsn_t)0, log_flags);
 743         }
 744
 745         /*
 746          * When shutting down, we need to insure that the AIL is pushed
 747          * to disk or the filesystem can appear corrupt from the PROM.
 748          */
 749         if ((flags & (SYNC_CLOSE|SYNC_WAIT)) == (SYNC_CLOSE|SYNC_WAIT)) {
 750                 XFS_bflush(mp->m_ddev_targp);
 751                 if (mp->m_rtdev_targp) {
 752                         XFS_bflush(mp->m_rtdev_targp);
 753                 }
 754         }
 755
 756         return XFS_ERROR(last_error);
 757 }