Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux...
[linux-2.6.git] / fs / xfs / linux-2.6 / xfs_lrw.c
1 /*
2  * Copyright (c) 2000-2003,2005 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_bit.h"
21 #include "xfs_log.h"
22 #include "xfs_inum.h"
23 #include "xfs_trans.h"
24 #include "xfs_sb.h"
25 #include "xfs_ag.h"
26 #include "xfs_dir2.h"
27 #include "xfs_alloc.h"
28 #include "xfs_dmapi.h"
29 #include "xfs_quota.h"
30 #include "xfs_mount.h"
31 #include "xfs_bmap_btree.h"
32 #include "xfs_alloc_btree.h"
33 #include "xfs_ialloc_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_bmap.h"
39 #include "xfs_btree.h"
40 #include "xfs_ialloc.h"
41 #include "xfs_rtalloc.h"
42 #include "xfs_error.h"
43 #include "xfs_itable.h"
44 #include "xfs_rw.h"
45 #include "xfs_attr.h"
46 #include "xfs_inode_item.h"
47 #include "xfs_buf_item.h"
48 #include "xfs_utils.h"
49 #include "xfs_iomap.h"
50 #include "xfs_vnodeops.h"
51
52 #include <linux/capability.h>
53 #include <linux/writeback.h>
54
55
56 #if defined(XFS_RW_TRACE)
57 void
58 xfs_rw_enter_trace(
59         int                     tag,
60         xfs_inode_t             *ip,
61         void                    *data,
62         size_t                  segs,
63         loff_t                  offset,
64         int                     ioflags)
65 {
66         if (ip->i_rwtrace == NULL)
67                 return;
68         ktrace_enter(ip->i_rwtrace,
69                 (void *)(unsigned long)tag,
70                 (void *)ip,
71                 (void *)((unsigned long)((ip->i_d.di_size >> 32) & 0xffffffff)),
72                 (void *)((unsigned long)(ip->i_d.di_size & 0xffffffff)),
73                 (void *)data,
74                 (void *)((unsigned long)segs),
75                 (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
76                 (void *)((unsigned long)(offset & 0xffffffff)),
77                 (void *)((unsigned long)ioflags),
78                 (void *)((unsigned long)((ip->i_new_size >> 32) & 0xffffffff)),
79                 (void *)((unsigned long)(ip->i_new_size & 0xffffffff)),
80                 (void *)((unsigned long)current_pid()),
81                 (void *)NULL,
82                 (void *)NULL,
83                 (void *)NULL,
84                 (void *)NULL);
85 }
86
87 void
88 xfs_inval_cached_trace(
89         xfs_inode_t     *ip,
90         xfs_off_t       offset,
91         xfs_off_t       len,
92         xfs_off_t       first,
93         xfs_off_t       last)
94 {
95
96         if (ip->i_rwtrace == NULL)
97                 return;
98         ktrace_enter(ip->i_rwtrace,
99                 (void *)(__psint_t)XFS_INVAL_CACHED,
100                 (void *)ip,
101                 (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
102                 (void *)((unsigned long)(offset & 0xffffffff)),
103                 (void *)((unsigned long)((len >> 32) & 0xffffffff)),
104                 (void *)((unsigned long)(len & 0xffffffff)),
105                 (void *)((unsigned long)((first >> 32) & 0xffffffff)),
106                 (void *)((unsigned long)(first & 0xffffffff)),
107                 (void *)((unsigned long)((last >> 32) & 0xffffffff)),
108                 (void *)((unsigned long)(last & 0xffffffff)),
109                 (void *)((unsigned long)current_pid()),
110                 (void *)NULL,
111                 (void *)NULL,
112                 (void *)NULL,
113                 (void *)NULL,
114                 (void *)NULL);
115 }
116 #endif
117
118 /*
119  *      xfs_iozero
120  *
121  *      xfs_iozero clears the specified range of buffer supplied,
122  *      and marks all the affected blocks as valid and modified.  If
123  *      an affected block is not allocated, it will be allocated.  If
124  *      an affected block is not completely overwritten, and is not
125  *      valid before the operation, it will be read from disk before
126  *      being partially zeroed.
127  */
128 STATIC int
129 xfs_iozero(
130         struct xfs_inode        *ip,    /* inode                        */
131         loff_t                  pos,    /* offset in file               */
132         size_t                  count)  /* size of data to zero         */
133 {
134         struct page             *page;
135         struct address_space    *mapping;
136         int                     status;
137
138         mapping = VFS_I(ip)->i_mapping;
139         do {
140                 unsigned offset, bytes;
141                 void *fsdata;
142
143                 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
144                 bytes = PAGE_CACHE_SIZE - offset;
145                 if (bytes > count)
146                         bytes = count;
147
148                 status = pagecache_write_begin(NULL, mapping, pos, bytes,
149                                         AOP_FLAG_UNINTERRUPTIBLE,
150                                         &page, &fsdata);
151                 if (status)
152                         break;
153
154                 zero_user(page, offset, bytes);
155
156                 status = pagecache_write_end(NULL, mapping, pos, bytes, bytes,
157                                         page, fsdata);
158                 WARN_ON(status <= 0); /* can't return less than zero! */
159                 pos += bytes;
160                 count -= bytes;
161                 status = 0;
162         } while (count);
163
164         return (-status);
165 }
166
167 ssize_t                 /* bytes read, or (-)  error */
168 xfs_read(
169         xfs_inode_t             *ip,
170         struct kiocb            *iocb,
171         const struct iovec      *iovp,
172         unsigned int            segs,
173         loff_t                  *offset,
174         int                     ioflags)
175 {
176         struct file             *file = iocb->ki_filp;
177         struct inode            *inode = file->f_mapping->host;
178         xfs_mount_t             *mp = ip->i_mount;
179         size_t                  size = 0;
180         ssize_t                 ret = 0;
181         xfs_fsize_t             n;
182         unsigned long           seg;
183
184
185         XFS_STATS_INC(xs_read_calls);
186
187         /* START copy & waste from filemap.c */
188         for (seg = 0; seg < segs; seg++) {
189                 const struct iovec *iv = &iovp[seg];
190
191                 /*
192                  * If any segment has a negative length, or the cumulative
193                  * length ever wraps negative then return -EINVAL.
194                  */
195                 size += iv->iov_len;
196                 if (unlikely((ssize_t)(size|iv->iov_len) < 0))
197                         return XFS_ERROR(-EINVAL);
198         }
199         /* END copy & waste from filemap.c */
200
201         if (unlikely(ioflags & IO_ISDIRECT)) {
202                 xfs_buftarg_t   *target =
203                         XFS_IS_REALTIME_INODE(ip) ?
204                                 mp->m_rtdev_targp : mp->m_ddev_targp;
205                 if ((*offset & target->bt_smask) ||
206                     (size & target->bt_smask)) {
207                         if (*offset == ip->i_size) {
208                                 return (0);
209                         }
210                         return -XFS_ERROR(EINVAL);
211                 }
212         }
213
214         n = XFS_MAXIOFFSET(mp) - *offset;
215         if ((n <= 0) || (size == 0))
216                 return 0;
217
218         if (n < size)
219                 size = n;
220
221         if (XFS_FORCED_SHUTDOWN(mp))
222                 return -EIO;
223
224         if (unlikely(ioflags & IO_ISDIRECT))
225                 mutex_lock(&inode->i_mutex);
226         xfs_ilock(ip, XFS_IOLOCK_SHARED);
227
228         if (DM_EVENT_ENABLED(ip, DM_EVENT_READ) && !(ioflags & IO_INVIS)) {
229                 int dmflags = FILP_DELAY_FLAG(file) | DM_SEM_FLAG_RD(ioflags);
230                 int iolock = XFS_IOLOCK_SHARED;
231
232                 ret = -XFS_SEND_DATA(mp, DM_EVENT_READ, ip, *offset, size,
233                                         dmflags, &iolock);
234                 if (ret) {
235                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
236                         if (unlikely(ioflags & IO_ISDIRECT))
237                                 mutex_unlock(&inode->i_mutex);
238                         return ret;
239                 }
240         }
241
242         if (unlikely(ioflags & IO_ISDIRECT)) {
243                 if (inode->i_mapping->nrpages)
244                         ret = -xfs_flushinval_pages(ip, (*offset & PAGE_CACHE_MASK),
245                                                     -1, FI_REMAPF_LOCKED);
246                 mutex_unlock(&inode->i_mutex);
247                 if (ret) {
248                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
249                         return ret;
250                 }
251         }
252
253         xfs_rw_enter_trace(XFS_READ_ENTER, ip,
254                                 (void *)iovp, segs, *offset, ioflags);
255
256         iocb->ki_pos = *offset;
257         ret = generic_file_aio_read(iocb, iovp, segs, *offset);
258         if (ret > 0)
259                 XFS_STATS_ADD(xs_read_bytes, ret);
260
261         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
262         return ret;
263 }
264
265 ssize_t
266 xfs_splice_read(
267         xfs_inode_t             *ip,
268         struct file             *infilp,
269         loff_t                  *ppos,
270         struct pipe_inode_info  *pipe,
271         size_t                  count,
272         int                     flags,
273         int                     ioflags)
274 {
275         xfs_mount_t             *mp = ip->i_mount;
276         ssize_t                 ret;
277
278         XFS_STATS_INC(xs_read_calls);
279         if (XFS_FORCED_SHUTDOWN(ip->i_mount))
280                 return -EIO;
281
282         xfs_ilock(ip, XFS_IOLOCK_SHARED);
283
284         if (DM_EVENT_ENABLED(ip, DM_EVENT_READ) && !(ioflags & IO_INVIS)) {
285                 int iolock = XFS_IOLOCK_SHARED;
286                 int error;
287
288                 error = XFS_SEND_DATA(mp, DM_EVENT_READ, ip, *ppos, count,
289                                         FILP_DELAY_FLAG(infilp), &iolock);
290                 if (error) {
291                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
292                         return -error;
293                 }
294         }
295         xfs_rw_enter_trace(XFS_SPLICE_READ_ENTER, ip,
296                            pipe, count, *ppos, ioflags);
297         ret = generic_file_splice_read(infilp, ppos, pipe, count, flags);
298         if (ret > 0)
299                 XFS_STATS_ADD(xs_read_bytes, ret);
300
301         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
302         return ret;
303 }
304
305 ssize_t
306 xfs_splice_write(
307         xfs_inode_t             *ip,
308         struct pipe_inode_info  *pipe,
309         struct file             *outfilp,
310         loff_t                  *ppos,
311         size_t                  count,
312         int                     flags,
313         int                     ioflags)
314 {
315         xfs_mount_t             *mp = ip->i_mount;
316         ssize_t                 ret;
317         struct inode            *inode = outfilp->f_mapping->host;
318         xfs_fsize_t             isize, new_size;
319
320         XFS_STATS_INC(xs_write_calls);
321         if (XFS_FORCED_SHUTDOWN(ip->i_mount))
322                 return -EIO;
323
324         xfs_ilock(ip, XFS_IOLOCK_EXCL);
325
326         if (DM_EVENT_ENABLED(ip, DM_EVENT_WRITE) && !(ioflags & IO_INVIS)) {
327                 int iolock = XFS_IOLOCK_EXCL;
328                 int error;
329
330                 error = XFS_SEND_DATA(mp, DM_EVENT_WRITE, ip, *ppos, count,
331                                         FILP_DELAY_FLAG(outfilp), &iolock);
332                 if (error) {
333                         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
334                         return -error;
335                 }
336         }
337
338         new_size = *ppos + count;
339
340         xfs_ilock(ip, XFS_ILOCK_EXCL);
341         if (new_size > ip->i_size)
342                 ip->i_new_size = new_size;
343         xfs_iunlock(ip, XFS_ILOCK_EXCL);
344
345         xfs_rw_enter_trace(XFS_SPLICE_WRITE_ENTER, ip,
346                            pipe, count, *ppos, ioflags);
347         ret = generic_file_splice_write(pipe, outfilp, ppos, count, flags);
348         if (ret > 0)
349                 XFS_STATS_ADD(xs_write_bytes, ret);
350
351         isize = i_size_read(inode);
352         if (unlikely(ret < 0 && ret != -EFAULT && *ppos > isize))
353                 *ppos = isize;
354
355         if (*ppos > ip->i_size) {
356                 xfs_ilock(ip, XFS_ILOCK_EXCL);
357                 if (*ppos > ip->i_size)
358                         ip->i_size = *ppos;
359                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
360         }
361
362         if (ip->i_new_size) {
363                 xfs_ilock(ip, XFS_ILOCK_EXCL);
364                 ip->i_new_size = 0;
365                 if (ip->i_d.di_size > ip->i_size)
366                         ip->i_d.di_size = ip->i_size;
367                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
368         }
369         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
370         return ret;
371 }
372
373 /*
374  * This routine is called to handle zeroing any space in the last
375  * block of the file that is beyond the EOF.  We do this since the
376  * size is being increased without writing anything to that block
377  * and we don't want anyone to read the garbage on the disk.
378  */
379 STATIC int                              /* error (positive) */
380 xfs_zero_last_block(
381         xfs_inode_t     *ip,
382         xfs_fsize_t     offset,
383         xfs_fsize_t     isize)
384 {
385         xfs_fileoff_t   last_fsb;
386         xfs_mount_t     *mp = ip->i_mount;
387         int             nimaps;
388         int             zero_offset;
389         int             zero_len;
390         int             error = 0;
391         xfs_bmbt_irec_t imap;
392
393         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
394
395         zero_offset = XFS_B_FSB_OFFSET(mp, isize);
396         if (zero_offset == 0) {
397                 /*
398                  * There are no extra bytes in the last block on disk to
399                  * zero, so return.
400                  */
401                 return 0;
402         }
403
404         last_fsb = XFS_B_TO_FSBT(mp, isize);
405         nimaps = 1;
406         error = xfs_bmapi(NULL, ip, last_fsb, 1, 0, NULL, 0, &imap,
407                           &nimaps, NULL, NULL);
408         if (error) {
409                 return error;
410         }
411         ASSERT(nimaps > 0);
412         /*
413          * If the block underlying isize is just a hole, then there
414          * is nothing to zero.
415          */
416         if (imap.br_startblock == HOLESTARTBLOCK) {
417                 return 0;
418         }
419         /*
420          * Zero the part of the last block beyond the EOF, and write it
421          * out sync.  We need to drop the ilock while we do this so we
422          * don't deadlock when the buffer cache calls back to us.
423          */
424         xfs_iunlock(ip, XFS_ILOCK_EXCL);
425
426         zero_len = mp->m_sb.sb_blocksize - zero_offset;
427         if (isize + zero_len > offset)
428                 zero_len = offset - isize;
429         error = xfs_iozero(ip, isize, zero_len);
430
431         xfs_ilock(ip, XFS_ILOCK_EXCL);
432         ASSERT(error >= 0);
433         return error;
434 }
435
436 /*
437  * Zero any on disk space between the current EOF and the new,
438  * larger EOF.  This handles the normal case of zeroing the remainder
439  * of the last block in the file and the unusual case of zeroing blocks
440  * out beyond the size of the file.  This second case only happens
441  * with fixed size extents and when the system crashes before the inode
442  * size was updated but after blocks were allocated.  If fill is set,
443  * then any holes in the range are filled and zeroed.  If not, the holes
444  * are left alone as holes.
445  */
446
447 int                                     /* error (positive) */
448 xfs_zero_eof(
449         xfs_inode_t     *ip,
450         xfs_off_t       offset,         /* starting I/O offset */
451         xfs_fsize_t     isize)          /* current inode size */
452 {
453         xfs_mount_t     *mp = ip->i_mount;
454         xfs_fileoff_t   start_zero_fsb;
455         xfs_fileoff_t   end_zero_fsb;
456         xfs_fileoff_t   zero_count_fsb;
457         xfs_fileoff_t   last_fsb;
458         xfs_fileoff_t   zero_off;
459         xfs_fsize_t     zero_len;
460         int             nimaps;
461         int             error = 0;
462         xfs_bmbt_irec_t imap;
463
464         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
465         ASSERT(offset > isize);
466
467         /*
468          * First handle zeroing the block on which isize resides.
469          * We only zero a part of that block so it is handled specially.
470          */
471         error = xfs_zero_last_block(ip, offset, isize);
472         if (error) {
473                 ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
474                 return error;
475         }
476
477         /*
478          * Calculate the range between the new size and the old
479          * where blocks needing to be zeroed may exist.  To get the
480          * block where the last byte in the file currently resides,
481          * we need to subtract one from the size and truncate back
482          * to a block boundary.  We subtract 1 in case the size is
483          * exactly on a block boundary.
484          */
485         last_fsb = isize ? XFS_B_TO_FSBT(mp, isize - 1) : (xfs_fileoff_t)-1;
486         start_zero_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)isize);
487         end_zero_fsb = XFS_B_TO_FSBT(mp, offset - 1);
488         ASSERT((xfs_sfiloff_t)last_fsb < (xfs_sfiloff_t)start_zero_fsb);
489         if (last_fsb == end_zero_fsb) {
490                 /*
491                  * The size was only incremented on its last block.
492                  * We took care of that above, so just return.
493                  */
494                 return 0;
495         }
496
497         ASSERT(start_zero_fsb <= end_zero_fsb);
498         while (start_zero_fsb <= end_zero_fsb) {
499                 nimaps = 1;
500                 zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
501                 error = xfs_bmapi(NULL, ip, start_zero_fsb, zero_count_fsb,
502                                   0, NULL, 0, &imap, &nimaps, NULL, NULL);
503                 if (error) {
504                         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
505                         return error;
506                 }
507                 ASSERT(nimaps > 0);
508
509                 if (imap.br_state == XFS_EXT_UNWRITTEN ||
510                     imap.br_startblock == HOLESTARTBLOCK) {
511                         /*
512                          * This loop handles initializing pages that were
513                          * partially initialized by the code below this
514                          * loop. It basically zeroes the part of the page
515                          * that sits on a hole and sets the page as P_HOLE
516                          * and calls remapf if it is a mapped file.
517                          */
518                         start_zero_fsb = imap.br_startoff + imap.br_blockcount;
519                         ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
520                         continue;
521                 }
522
523                 /*
524                  * There are blocks we need to zero.
525                  * Drop the inode lock while we're doing the I/O.
526                  * We'll still have the iolock to protect us.
527                  */
528                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
529
530                 zero_off = XFS_FSB_TO_B(mp, start_zero_fsb);
531                 zero_len = XFS_FSB_TO_B(mp, imap.br_blockcount);
532
533                 if ((zero_off + zero_len) > offset)
534                         zero_len = offset - zero_off;
535
536                 error = xfs_iozero(ip, zero_off, zero_len);
537                 if (error) {
538                         goto out_lock;
539                 }
540
541                 start_zero_fsb = imap.br_startoff + imap.br_blockcount;
542                 ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
543
544                 xfs_ilock(ip, XFS_ILOCK_EXCL);
545         }
546
547         return 0;
548
549 out_lock:
550         xfs_ilock(ip, XFS_ILOCK_EXCL);
551         ASSERT(error >= 0);
552         return error;
553 }
554
555 ssize_t                         /* bytes written, or (-) error */
556 xfs_write(
557         struct xfs_inode        *xip,
558         struct kiocb            *iocb,
559         const struct iovec      *iovp,
560         unsigned int            nsegs,
561         loff_t                  *offset,
562         int                     ioflags)
563 {
564         struct file             *file = iocb->ki_filp;
565         struct address_space    *mapping = file->f_mapping;
566         struct inode            *inode = mapping->host;
567         unsigned long           segs = nsegs;
568         xfs_mount_t             *mp;
569         ssize_t                 ret = 0, error = 0;
570         xfs_fsize_t             isize, new_size;
571         int                     iolock;
572         int                     eventsent = 0;
573         size_t                  ocount = 0, count;
574         loff_t                  pos;
575         int                     need_i_mutex;
576
577         XFS_STATS_INC(xs_write_calls);
578
579         error = generic_segment_checks(iovp, &segs, &ocount, VERIFY_READ);
580         if (error)
581                 return error;
582
583         count = ocount;
584         pos = *offset;
585
586         if (count == 0)
587                 return 0;
588
589         mp = xip->i_mount;
590
591         xfs_wait_for_freeze(mp, SB_FREEZE_WRITE);
592
593         if (XFS_FORCED_SHUTDOWN(mp))
594                 return -EIO;
595
596 relock:
597         if (ioflags & IO_ISDIRECT) {
598                 iolock = XFS_IOLOCK_SHARED;
599                 need_i_mutex = 0;
600         } else {
601                 iolock = XFS_IOLOCK_EXCL;
602                 need_i_mutex = 1;
603                 mutex_lock(&inode->i_mutex);
604         }
605
606         xfs_ilock(xip, XFS_ILOCK_EXCL|iolock);
607
608 start:
609         error = -generic_write_checks(file, &pos, &count,
610                                         S_ISBLK(inode->i_mode));
611         if (error) {
612                 xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
613                 goto out_unlock_mutex;
614         }
615
616         if ((DM_EVENT_ENABLED(xip, DM_EVENT_WRITE) &&
617             !(ioflags & IO_INVIS) && !eventsent)) {
618                 int             dmflags = FILP_DELAY_FLAG(file);
619
620                 if (need_i_mutex)
621                         dmflags |= DM_FLAGS_IMUX;
622
623                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
624                 error = XFS_SEND_DATA(xip->i_mount, DM_EVENT_WRITE, xip,
625                                       pos, count, dmflags, &iolock);
626                 if (error) {
627                         goto out_unlock_internal;
628                 }
629                 xfs_ilock(xip, XFS_ILOCK_EXCL);
630                 eventsent = 1;
631
632                 /*
633                  * The iolock was dropped and reacquired in XFS_SEND_DATA
634                  * so we have to recheck the size when appending.
635                  * We will only "goto start;" once, since having sent the
636                  * event prevents another call to XFS_SEND_DATA, which is
637                  * what allows the size to change in the first place.
638                  */
639                 if ((file->f_flags & O_APPEND) && pos != xip->i_size)
640                         goto start;
641         }
642
643         if (ioflags & IO_ISDIRECT) {
644                 xfs_buftarg_t   *target =
645                         XFS_IS_REALTIME_INODE(xip) ?
646                                 mp->m_rtdev_targp : mp->m_ddev_targp;
647
648                 if ((pos & target->bt_smask) || (count & target->bt_smask)) {
649                         xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
650                         return XFS_ERROR(-EINVAL);
651                 }
652
653                 if (!need_i_mutex && (mapping->nrpages || pos > xip->i_size)) {
654                         xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
655                         iolock = XFS_IOLOCK_EXCL;
656                         need_i_mutex = 1;
657                         mutex_lock(&inode->i_mutex);
658                         xfs_ilock(xip, XFS_ILOCK_EXCL|iolock);
659                         goto start;
660                 }
661         }
662
663         new_size = pos + count;
664         if (new_size > xip->i_size)
665                 xip->i_new_size = new_size;
666
667         if (likely(!(ioflags & IO_INVIS)))
668                 file_update_time(file);
669
670         /*
671          * If the offset is beyond the size of the file, we have a couple
672          * of things to do. First, if there is already space allocated
673          * we need to either create holes or zero the disk or ...
674          *
675          * If there is a page where the previous size lands, we need
676          * to zero it out up to the new size.
677          */
678
679         if (pos > xip->i_size) {
680                 error = xfs_zero_eof(xip, pos, xip->i_size);
681                 if (error) {
682                         xfs_iunlock(xip, XFS_ILOCK_EXCL);
683                         goto out_unlock_internal;
684                 }
685         }
686         xfs_iunlock(xip, XFS_ILOCK_EXCL);
687
688         /*
689          * If we're writing the file then make sure to clear the
690          * setuid and setgid bits if the process is not being run
691          * by root.  This keeps people from modifying setuid and
692          * setgid binaries.
693          */
694
695         if (((xip->i_d.di_mode & S_ISUID) ||
696             ((xip->i_d.di_mode & (S_ISGID | S_IXGRP)) ==
697                 (S_ISGID | S_IXGRP))) &&
698              !capable(CAP_FSETID)) {
699                 error = xfs_write_clear_setuid(xip);
700                 if (likely(!error))
701                         error = -file_remove_suid(file);
702                 if (unlikely(error)) {
703                         goto out_unlock_internal;
704                 }
705         }
706
707         /* We can write back this queue in page reclaim */
708         current->backing_dev_info = mapping->backing_dev_info;
709
710         if ((ioflags & IO_ISDIRECT)) {
711                 if (mapping->nrpages) {
712                         WARN_ON(need_i_mutex == 0);
713                         xfs_inval_cached_trace(xip, pos, -1,
714                                         (pos & PAGE_CACHE_MASK), -1);
715                         error = xfs_flushinval_pages(xip,
716                                         (pos & PAGE_CACHE_MASK),
717                                         -1, FI_REMAPF_LOCKED);
718                         if (error)
719                                 goto out_unlock_internal;
720                 }
721
722                 if (need_i_mutex) {
723                         /* demote the lock now the cached pages are gone */
724                         xfs_ilock_demote(xip, XFS_IOLOCK_EXCL);
725                         mutex_unlock(&inode->i_mutex);
726
727                         iolock = XFS_IOLOCK_SHARED;
728                         need_i_mutex = 0;
729                 }
730
731                 xfs_rw_enter_trace(XFS_DIOWR_ENTER, xip, (void *)iovp, segs,
732                                 *offset, ioflags);
733                 ret = generic_file_direct_write(iocb, iovp,
734                                 &segs, pos, offset, count, ocount);
735
736                 /*
737                  * direct-io write to a hole: fall through to buffered I/O
738                  * for completing the rest of the request.
739                  */
740                 if (ret >= 0 && ret != count) {
741                         XFS_STATS_ADD(xs_write_bytes, ret);
742
743                         pos += ret;
744                         count -= ret;
745
746                         ioflags &= ~IO_ISDIRECT;
747                         xfs_iunlock(xip, iolock);
748                         goto relock;
749                 }
750         } else {
751                 int enospc = 0;
752                 ssize_t ret2 = 0;
753
754 write_retry:
755                 xfs_rw_enter_trace(XFS_WRITE_ENTER, xip, (void *)iovp, segs,
756                                 *offset, ioflags);
757                 ret2 = generic_file_buffered_write(iocb, iovp, segs,
758                                 pos, offset, count, ret);
759                 /*
760                  * if we just got an ENOSPC, flush the inode now we
761                  * aren't holding any page locks and retry *once*
762                  */
763                 if (ret2 == -ENOSPC && !enospc) {
764                         error = xfs_flush_pages(xip, 0, -1, 0, FI_NONE);
765                         if (error)
766                                 goto out_unlock_internal;
767                         enospc = 1;
768                         goto write_retry;
769                 }
770                 ret = ret2;
771         }
772
773         current->backing_dev_info = NULL;
774
775         isize = i_size_read(inode);
776         if (unlikely(ret < 0 && ret != -EFAULT && *offset > isize))
777                 *offset = isize;
778
779         if (*offset > xip->i_size) {
780                 xfs_ilock(xip, XFS_ILOCK_EXCL);
781                 if (*offset > xip->i_size)
782                         xip->i_size = *offset;
783                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
784         }
785
786         if (ret == -ENOSPC &&
787             DM_EVENT_ENABLED(xip, DM_EVENT_NOSPACE) && !(ioflags & IO_INVIS)) {
788                 xfs_iunlock(xip, iolock);
789                 if (need_i_mutex)
790                         mutex_unlock(&inode->i_mutex);
791                 error = XFS_SEND_NAMESP(xip->i_mount, DM_EVENT_NOSPACE, xip,
792                                 DM_RIGHT_NULL, xip, DM_RIGHT_NULL, NULL, NULL,
793                                 0, 0, 0); /* Delay flag intentionally  unused */
794                 if (need_i_mutex)
795                         mutex_lock(&inode->i_mutex);
796                 xfs_ilock(xip, iolock);
797                 if (error)
798                         goto out_unlock_internal;
799                 goto start;
800         }
801
802         error = -ret;
803         if (ret <= 0)
804                 goto out_unlock_internal;
805
806         XFS_STATS_ADD(xs_write_bytes, ret);
807
808         /* Handle various SYNC-type writes */
809         if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
810                 loff_t end = pos + ret - 1;
811                 int error2;
812
813                 xfs_iunlock(xip, iolock);
814                 if (need_i_mutex)
815                         mutex_unlock(&inode->i_mutex);
816
817                 error2 = filemap_write_and_wait_range(mapping, pos, end);
818                 if (!error)
819                         error = error2;
820                 if (need_i_mutex)
821                         mutex_lock(&inode->i_mutex);
822                 xfs_ilock(xip, iolock);
823
824                 error2 = xfs_fsync(xip);
825                 if (!error)
826                         error = error2;
827         }
828
829  out_unlock_internal:
830         if (xip->i_new_size) {
831                 xfs_ilock(xip, XFS_ILOCK_EXCL);
832                 xip->i_new_size = 0;
833                 /*
834                  * If this was a direct or synchronous I/O that failed (such
835                  * as ENOSPC) then part of the I/O may have been written to
836                  * disk before the error occured.  In this case the on-disk
837                  * file size may have been adjusted beyond the in-memory file
838                  * size and now needs to be truncated back.
839                  */
840                 if (xip->i_d.di_size > xip->i_size)
841                         xip->i_d.di_size = xip->i_size;
842                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
843         }
844         xfs_iunlock(xip, iolock);
845  out_unlock_mutex:
846         if (need_i_mutex)
847                 mutex_unlock(&inode->i_mutex);
848         return -error;
849 }
850
851 /*
852  * All xfs metadata buffers except log state machine buffers
853  * get this attached as their b_bdstrat callback function.
854  * This is so that we can catch a buffer
855  * after prematurely unpinning it to forcibly shutdown the filesystem.
856  */
857 int
858 xfs_bdstrat_cb(struct xfs_buf *bp)
859 {
860         if (XFS_FORCED_SHUTDOWN(bp->b_mount)) {
861                 xfs_buftrace("XFS__BDSTRAT IOERROR", bp);
862                 /*
863                  * Metadata write that didn't get logged but
864                  * written delayed anyway. These aren't associated
865                  * with a transaction, and can be ignored.
866                  */
867                 if (XFS_BUF_IODONE_FUNC(bp) == NULL &&
868                     (XFS_BUF_ISREAD(bp)) == 0)
869                         return (xfs_bioerror_relse(bp));
870                 else
871                         return (xfs_bioerror(bp));
872         }
873
874         xfs_buf_iorequest(bp);
875         return 0;
876 }
877
878 /*
879  * Wrapper around bdstrat so that we can stop data from going to disk in case
880  * we are shutting down the filesystem.  Typically user data goes thru this
881  * path; one of the exceptions is the superblock.
882  */
883 void
884 xfsbdstrat(
885         struct xfs_mount        *mp,
886         struct xfs_buf          *bp)
887 {
888         ASSERT(mp);
889         if (!XFS_FORCED_SHUTDOWN(mp)) {
890                 xfs_buf_iorequest(bp);
891                 return;
892         }
893
894         xfs_buftrace("XFSBDSTRAT IOERROR", bp);
895         xfs_bioerror_relse(bp);
896 }
897
898 /*
899  * If the underlying (data/log/rt) device is readonly, there are some
900  * operations that cannot proceed.
901  */
902 int
903 xfs_dev_is_read_only(
904         xfs_mount_t             *mp,
905         char                    *message)
906 {
907         if (xfs_readonly_buftarg(mp->m_ddev_targp) ||
908             xfs_readonly_buftarg(mp->m_logdev_targp) ||
909             (mp->m_rtdev_targp && xfs_readonly_buftarg(mp->m_rtdev_targp))) {
910                 cmn_err(CE_NOTE,
911                         "XFS: %s required on read-only device.", message);
912                 cmn_err(CE_NOTE,
913                         "XFS: write access unavailable, cannot proceed.");
914                 return EROFS;
915         }
916         return 0;
917 }