Merge commit 'v2.6.27-rc3' into x86/xsave
[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         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 }