Merge commit 'v2.6.27-rc6' into x86/cleanups
[linux-2.6] / 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 }