err.no Git - linux-2.6/blob - 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_acl.h"
  46 #include "xfs_attr.h"
  47 #include "xfs_inode_item.h"
  48 #include "xfs_buf_item.h"
  49 #include "xfs_utils.h"
  50 #include "xfs_iomap.h"
  51 #include "xfs_vnodeops.h"
  52
  53 #include <linux/capability.h>
  54 #include <linux/mount.h>
  55 #include <linux/writeback.h>
  56
  57
  58 #if defined(XFS_RW_TRACE)
  59 void
  60 xfs_rw_enter_trace(
  61         int                     tag,
  62         xfs_inode_t             *ip,
  63         void                    *data,
  64         size_t                  segs,
  65         loff_t                  offset,
  66         int                     ioflags)
  67 {
  68         if (ip->i_rwtrace == NULL)
  69                 return;
  70         ktrace_enter(ip->i_rwtrace,
  71                 (void *)(unsigned long)tag,
  72                 (void *)ip,
  73                 (void *)((unsigned long)((ip->i_d.di_size >> 32) & 0xffffffff)),
  74                 (void *)((unsigned long)(ip->i_d.di_size & 0xffffffff)),
  75                 (void *)data,
  76                 (void *)((unsigned long)segs),
  77                 (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
  78                 (void *)((unsigned long)(offset & 0xffffffff)),
  79                 (void *)((unsigned long)ioflags),
  80                 (void *)((unsigned long)((ip->i_new_size >> 32) & 0xffffffff)),
  81                 (void *)((unsigned long)(ip->i_new_size & 0xffffffff)),
  82                 (void *)((unsigned long)current_pid()),
  83                 (void *)NULL,
  84                 (void *)NULL,
  85                 (void *)NULL,
  86                 (void *)NULL);
  87 }
  88
  89 void
  90 xfs_inval_cached_trace(
  91         xfs_inode_t     *ip,
  92         xfs_off_t       offset,
  93         xfs_off_t       len,
  94         xfs_off_t       first,
  95         xfs_off_t       last)
  96 {
  97
  98         if (ip->i_rwtrace == NULL)
  99                 return;
 100         ktrace_enter(ip->i_rwtrace,
 101                 (void *)(__psint_t)XFS_INVAL_CACHED,
 102                 (void *)ip,
 103                 (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
 104                 (void *)((unsigned long)(offset & 0xffffffff)),
 105                 (void *)((unsigned long)((len >> 32) & 0xffffffff)),
 106                 (void *)((unsigned long)(len & 0xffffffff)),
 107                 (void *)((unsigned long)((first >> 32) & 0xffffffff)),
 108                 (void *)((unsigned long)(first & 0xffffffff)),
 109                 (void *)((unsigned long)((last >> 32) & 0xffffffff)),
 110                 (void *)((unsigned long)(last & 0xffffffff)),
 111                 (void *)((unsigned long)current_pid()),
 112                 (void *)NULL,
 113                 (void *)NULL,
 114                 (void *)NULL,
 115                 (void *)NULL,
 116                 (void *)NULL);
 117 }
 118 #endif
 119
 120 /*
 121  *      xfs_iozero
 122  *
 123  *      xfs_iozero clears the specified range of buffer supplied,
 124  *      and marks all the affected blocks as valid and modified.  If
 125  *      an affected block is not allocated, it will be allocated.  If
 126  *      an affected block is not completely overwritten, and is not
 127  *      valid before the operation, it will be read from disk before
 128  *      being partially zeroed.
 129  */
 130 STATIC int
 131 xfs_iozero(
 132         struct xfs_inode        *ip,    /* inode                        */
 133         loff_t                  pos,    /* offset in file               */
 134         size_t                  count)  /* size of data to zero         */
 135 {
 136         struct page             *page;
 137         struct address_space    *mapping;
 138         int                     status;
 139
 140         mapping = ip->i_vnode->i_mapping;
 141         do {
 142                 unsigned offset, bytes;
 143                 void *fsdata;
 144
 145                 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
 146                 bytes = PAGE_CACHE_SIZE - offset;
 147                 if (bytes > count)
 148                         bytes = count;
 149
 150                 status = pagecache_write_begin(NULL, mapping, pos, bytes,
 151                                         AOP_FLAG_UNINTERRUPTIBLE,
 152                                         &page, &fsdata);
 153                 if (status)
 154                         break;
 155
 156                 zero_user(page, offset, bytes);
 157
 158                 status = pagecache_write_end(NULL, mapping, pos, bytes, bytes,
 159                                         page, fsdata);
 160                 WARN_ON(status <= 0); /* can't return less than zero! */
 161                 pos += bytes;
 162                 count -= bytes;
 163                 status = 0;
 164         } while (count);
 165
 166         return (-status);
 167 }
 168
 169 ssize_t                 /* bytes read, or (-)  error */
 170 xfs_read(
 171         xfs_inode_t             *ip,
 172         struct kiocb            *iocb,
 173         const struct iovec      *iovp,
 174         unsigned int            segs,
 175         loff_t                  *offset,
 176         int                     ioflags)
 177 {
 178         struct file             *file = iocb->ki_filp;
 179         struct inode            *inode = file->f_mapping->host;
 180         xfs_mount_t             *mp = ip->i_mount;
 181         size_t                  size = 0;
 182         ssize_t                 ret = 0;
 183         xfs_fsize_t             n;
 184         unsigned long           seg;
 185
 186
 187         XFS_STATS_INC(xs_read_calls);
 188
 189         /* START copy & waste from filemap.c */
 190         for (seg = 0; seg < segs; seg++) {
 191                 const struct iovec *iv = &iovp[seg];
 192
 193                 /*
 194                  * If any segment has a negative length, or the cumulative
 195                  * length ever wraps negative then return -EINVAL.
 196                  */
 197                 size += iv->iov_len;
 198                 if (unlikely((ssize_t)(size|iv->iov_len) < 0))
 199                         return XFS_ERROR(-EINVAL);
 200         }
 201         /* END copy & waste from filemap.c */
 202
 203         if (unlikely(ioflags & IO_ISDIRECT)) {
 204                 xfs_buftarg_t   *target =
 205                         XFS_IS_REALTIME_INODE(ip) ?
 206                                 mp->m_rtdev_targp : mp->m_ddev_targp;
 207                 if ((*offset & target->bt_smask) ||
 208                     (size & target->bt_smask)) {
 209                         if (*offset == ip->i_size) {
 210                                 return (0);
 211                         }
 212                         return -XFS_ERROR(EINVAL);
 213                 }
 214         }
 215
 216         n = XFS_MAXIOFFSET(mp) - *offset;
 217         if ((n <= 0) || (size == 0))
 218                 return 0;
 219
 220         if (n < size)
 221                 size = n;
 222
 223         if (XFS_FORCED_SHUTDOWN(mp))
 224                 return -EIO;
 225
 226         if (unlikely(ioflags & IO_ISDIRECT))
 227                 mutex_lock(&inode->i_mutex);
 228         xfs_ilock(ip, XFS_IOLOCK_SHARED);
 229
 230         if (DM_EVENT_ENABLED(ip, DM_EVENT_READ) && !(ioflags & IO_INVIS)) {
 231                 int dmflags = FILP_DELAY_FLAG(file) | DM_SEM_FLAG_RD(ioflags);
 232                 int iolock = XFS_IOLOCK_SHARED;
 233
 234                 ret = -XFS_SEND_DATA(mp, DM_EVENT_READ, ip, *offset, size,
 235                                         dmflags, &iolock);
 236                 if (ret) {
 237                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 238                         if (unlikely(ioflags & IO_ISDIRECT))
 239                                 mutex_unlock(&inode->i_mutex);
 240                         return ret;
 241                 }
 242         }
 243
 244         if (unlikely(ioflags & IO_ISDIRECT)) {
 245                 if (inode->i_mapping->nrpages)
 246                         ret = xfs_flushinval_pages(ip, (*offset & PAGE_CACHE_MASK),
 247                                                     -1, FI_REMAPF_LOCKED);
 248                 mutex_unlock(&inode->i_mutex);
 249                 if (ret) {
 250                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 251                         return ret;
 252                 }
 253         }
 254
 255         xfs_rw_enter_trace(XFS_READ_ENTER, ip,
 256                                 (void *)iovp, segs, *offset, ioflags);
 257
 258         iocb->ki_pos = *offset;
 259         ret = generic_file_aio_read(iocb, iovp, segs, *offset);
 260         if (ret == -EIOCBQUEUED && !(ioflags & IO_ISAIO))
 261                 ret = wait_on_sync_kiocb(iocb);
 262         if (ret > 0)
 263                 XFS_STATS_ADD(xs_read_bytes, ret);
 264
 265         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 266         return ret;
 267 }
 268
 269 ssize_t
 270 xfs_splice_read(
 271         xfs_inode_t             *ip,
 272         struct file             *infilp,
 273         loff_t                  *ppos,
 274         struct pipe_inode_info  *pipe,
 275         size_t                  count,
 276         int                     flags,
 277         int                     ioflags)
 278 {
 279         xfs_mount_t             *mp = ip->i_mount;
 280         ssize_t                 ret;
 281
 282         XFS_STATS_INC(xs_read_calls);
 283         if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 284                 return -EIO;
 285
 286         xfs_ilock(ip, XFS_IOLOCK_SHARED);
 287
 288         if (DM_EVENT_ENABLED(ip, DM_EVENT_READ) && !(ioflags & IO_INVIS)) {
 289                 int iolock = XFS_IOLOCK_SHARED;
 290                 int error;
 291
 292                 error = XFS_SEND_DATA(mp, DM_EVENT_READ, ip, *ppos, count,
 293                                         FILP_DELAY_FLAG(infilp), &iolock);
 294                 if (error) {
 295                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 296                         return -error;
 297                 }
 298         }
 299         xfs_rw_enter_trace(XFS_SPLICE_READ_ENTER, ip,
 300                            pipe, count, *ppos, ioflags);
 301         ret = generic_file_splice_read(infilp, ppos, pipe, count, flags);
 302         if (ret > 0)
 303                 XFS_STATS_ADD(xs_read_bytes, ret);
 304
 305         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 306         return ret;
 307 }
 308
 309 ssize_t
 310 xfs_splice_write(
 311         xfs_inode_t             *ip,
 312         struct pipe_inode_info  *pipe,
 313         struct file             *outfilp,
 314         loff_t                  *ppos,
 315         size_t                  count,
 316         int                     flags,
 317         int                     ioflags)
 318 {
 319         xfs_mount_t             *mp = ip->i_mount;
 320         ssize_t                 ret;
 321         struct inode            *inode = outfilp->f_mapping->host;
 322         xfs_fsize_t             isize, new_size;
 323
 324         XFS_STATS_INC(xs_write_calls);
 325         if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 326                 return -EIO;
 327
 328         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 329
 330         if (DM_EVENT_ENABLED(ip, DM_EVENT_WRITE) && !(ioflags & IO_INVIS)) {
 331                 int iolock = XFS_IOLOCK_EXCL;
 332                 int error;
 333
 334                 error = XFS_SEND_DATA(mp, DM_EVENT_WRITE, ip, *ppos, count,
 335                                         FILP_DELAY_FLAG(outfilp), &iolock);
 336                 if (error) {
 337                         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 338                         return -error;
 339                 }
 340         }
 341
 342         new_size = *ppos + count;
 343
 344         xfs_ilock(ip, XFS_ILOCK_EXCL);
 345         if (new_size > ip->i_size)
 346                 ip->i_new_size = new_size;
 347         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 348
 349         xfs_rw_enter_trace(XFS_SPLICE_WRITE_ENTER, ip,
 350                            pipe, count, *ppos, ioflags);
 351         ret = generic_file_splice_write(pipe, outfilp, ppos, count, flags);
 352         if (ret > 0)
 353                 XFS_STATS_ADD(xs_write_bytes, ret);
 354
 355         isize = i_size_read(inode);
 356         if (unlikely(ret < 0 && ret != -EFAULT && *ppos > isize))
 357                 *ppos = isize;
 358
 359         if (*ppos > ip->i_size) {
 360                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 361                 if (*ppos > ip->i_size)
 362                         ip->i_size = *ppos;
 363                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 364         }
 365
 366         if (ip->i_new_size) {
 367                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 368                 ip->i_new_size = 0;
 369                 if (ip->i_d.di_size > ip->i_size)
 370                         ip->i_d.di_size = ip->i_size;
 371                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 372         }
 373         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 374         return ret;
 375 }
 376
 377 /*
 378  * This routine is called to handle zeroing any space in the last
 379  * block of the file that is beyond the EOF.  We do this since the
 380  * size is being increased without writing anything to that block
 381  * and we don't want anyone to read the garbage on the disk.
 382  */
 383 STATIC int                              /* error (positive) */
 384 xfs_zero_last_block(
 385         xfs_inode_t     *ip,
 386         xfs_fsize_t     offset,
 387         xfs_fsize_t     isize)
 388 {
 389         xfs_fileoff_t   last_fsb;
 390         xfs_mount_t     *mp = ip->i_mount;
 391         int             nimaps;
 392         int             zero_offset;
 393         int             zero_len;
 394         int             error = 0;
 395         xfs_bmbt_irec_t imap;
 396
 397         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 398
 399         zero_offset = XFS_B_FSB_OFFSET(mp, isize);
 400         if (zero_offset == 0) {
 401                 /*
 402                  * There are no extra bytes in the last block on disk to
 403                  * zero, so return.
 404                  */
 405                 return 0;
 406         }
 407
 408         last_fsb = XFS_B_TO_FSBT(mp, isize);
 409         nimaps = 1;
 410         error = xfs_bmapi(NULL, ip, last_fsb, 1, 0, NULL, 0, &imap,
 411                           &nimaps, NULL, NULL);
 412         if (error) {
 413                 return error;
 414         }
 415         ASSERT(nimaps > 0);
 416         /*
 417          * If the block underlying isize is just a hole, then there
 418          * is nothing to zero.
 419          */
 420         if (imap.br_startblock == HOLESTARTBLOCK) {
 421                 return 0;
 422         }
 423         /*
 424          * Zero the part of the last block beyond the EOF, and write it
 425          * out sync.  We need to drop the ilock while we do this so we
 426          * don't deadlock when the buffer cache calls back to us.
 427          */
 428         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 429
 430         zero_len = mp->m_sb.sb_blocksize - zero_offset;
 431         if (isize + zero_len > offset)
 432                 zero_len = offset - isize;
 433         error = xfs_iozero(ip, isize, zero_len);
 434
 435         xfs_ilock(ip, XFS_ILOCK_EXCL);
 436         ASSERT(error >= 0);
 437         return error;
 438 }
 439
 440 /*
 441  * Zero any on disk space between the current EOF and the new,
 442  * larger EOF.  This handles the normal case of zeroing the remainder
 443  * of the last block in the file and the unusual case of zeroing blocks
 444  * out beyond the size of the file.  This second case only happens
 445  * with fixed size extents and when the system crashes before the inode
 446  * size was updated but after blocks were allocated.  If fill is set,
 447  * then any holes in the range are filled and zeroed.  If not, the holes
 448  * are left alone as holes.
 449  */
 450
 451 int                                     /* error (positive) */
 452 xfs_zero_eof(
 453         xfs_inode_t     *ip,
 454         xfs_off_t       offset,         /* starting I/O offset */
 455         xfs_fsize_t     isize)          /* current inode size */
 456 {
 457         xfs_mount_t     *mp = ip->i_mount;
 458         xfs_fileoff_t   start_zero_fsb;
 459         xfs_fileoff_t   end_zero_fsb;
 460         xfs_fileoff_t   zero_count_fsb;
 461         xfs_fileoff_t   last_fsb;
 462         xfs_fileoff_t   zero_off;
 463         xfs_fsize_t     zero_len;
 464         int             nimaps;
 465         int             error = 0;
 466         xfs_bmbt_irec_t imap;
 467
 468         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
 469         ASSERT(offset > isize);
 470
 471         /*
 472          * First handle zeroing the block on which isize resides.
 473          * We only zero a part of that block so it is handled specially.
 474          */
 475         error = xfs_zero_last_block(ip, offset, isize);
 476         if (error) {
 477                 ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
 478                 return error;
 479         }
 480
 481         /*
 482          * Calculate the range between the new size and the old
 483          * where blocks needing to be zeroed may exist.  To get the
 484          * block where the last byte in the file currently resides,
 485          * we need to subtract one from the size and truncate back
 486          * to a block boundary.  We subtract 1 in case the size is
 487          * exactly on a block boundary.
 488          */
 489         last_fsb = isize ? XFS_B_TO_FSBT(mp, isize - 1) : (xfs_fileoff_t)-1;
 490         start_zero_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)isize);
 491         end_zero_fsb = XFS_B_TO_FSBT(mp, offset - 1);
 492         ASSERT((xfs_sfiloff_t)last_fsb < (xfs_sfiloff_t)start_zero_fsb);
 493         if (last_fsb == end_zero_fsb) {
 494                 /*
 495                  * The size was only incremented on its last block.
 496                  * We took care of that above, so just return.
 497                  */
 498                 return 0;
 499         }
 500
 501         ASSERT(start_zero_fsb <= end_zero_fsb);
 502         while (start_zero_fsb <= end_zero_fsb) {
 503                 nimaps = 1;
 504                 zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
 505                 error = xfs_bmapi(NULL, ip, start_zero_fsb, zero_count_fsb,
 506                                   0, NULL, 0, &imap, &nimaps, NULL, NULL);
 507                 if (error) {
 508                         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
 509                         return error;
 510                 }
 511                 ASSERT(nimaps > 0);
 512
 513                 if (imap.br_state == XFS_EXT_UNWRITTEN ||
 514                     imap.br_startblock == HOLESTARTBLOCK) {
 515                         /*
 516                          * This loop handles initializing pages that were
 517                          * partially initialized by the code below this
 518                          * loop. It basically zeroes the part of the page
 519                          * that sits on a hole and sets the page as P_HOLE
 520                          * and calls remapf if it is a mapped file.
 521                          */
 522                         start_zero_fsb = imap.br_startoff + imap.br_blockcount;
 523                         ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 524                         continue;
 525                 }
 526
 527                 /*
 528                  * There are blocks we need to zero.
 529                  * Drop the inode lock while we're doing the I/O.
 530                  * We'll still have the iolock to protect us.
 531                  */
 532                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 533
 534                 zero_off = XFS_FSB_TO_B(mp, start_zero_fsb);
 535                 zero_len = XFS_FSB_TO_B(mp, imap.br_blockcount);
 536
 537                 if ((zero_off + zero_len) > offset)
 538                         zero_len = offset - zero_off;
 539
 540                 error = xfs_iozero(ip, zero_off, zero_len);
 541                 if (error) {
 542                         goto out_lock;
 543                 }
 544
 545                 start_zero_fsb = imap.br_startoff + imap.br_blockcount;
 546                 ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 547
 548                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 549         }
 550
 551         return 0;
 552
 553 out_lock:
 554         xfs_ilock(ip, XFS_ILOCK_EXCL);
 555         ASSERT(error >= 0);
 556         return error;
 557 }
 558
 559 ssize_t                         /* bytes written, or (-) error */
 560 xfs_write(
 561         struct xfs_inode        *xip,
 562         struct kiocb            *iocb,
 563         const struct iovec      *iovp,
 564         unsigned int            nsegs,
 565         loff_t                  *offset,
 566         int                     ioflags)
 567 {
 568         struct file             *file = iocb->ki_filp;
 569         struct address_space    *mapping = file->f_mapping;
 570         struct inode            *inode = mapping->host;
 571         unsigned long           segs = nsegs;
 572         xfs_mount_t             *mp;
 573         ssize_t                 ret = 0, error = 0;
 574         xfs_fsize_t             isize, new_size;
 575         int                     iolock;
 576         int                     eventsent = 0;
 577         size_t                  ocount = 0, count;
 578         loff_t                  pos;
 579         int                     need_i_mutex;
 580
 581         XFS_STATS_INC(xs_write_calls);
 582
 583         error = generic_segment_checks(iovp, &segs, &ocount, VERIFY_READ);
 584         if (error)
 585                 return error;
 586
 587         count = ocount;
 588         pos = *offset;
 589
 590         if (count == 0)
 591                 return 0;
 592
 593         mp = xip->i_mount;
 594
 595         xfs_wait_for_freeze(mp, SB_FREEZE_WRITE);
 596
 597         if (XFS_FORCED_SHUTDOWN(mp))
 598                 return -EIO;
 599
 600 relock:
 601         if (ioflags & IO_ISDIRECT) {
 602                 iolock = XFS_IOLOCK_SHARED;
 603                 need_i_mutex = 0;
 604         } else {
 605                 iolock = XFS_IOLOCK_EXCL;
 606                 need_i_mutex = 1;
 607                 mutex_lock(&inode->i_mutex);
 608         }
 609
 610         xfs_ilock(xip, XFS_ILOCK_EXCL|iolock);
 611
 612 start:
 613         error = -generic_write_checks(file, &pos, &count,
 614                                         S_ISBLK(inode->i_mode));
 615         if (error) {
 616                 xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
 617                 goto out_unlock_mutex;
 618         }
 619
 620         if ((DM_EVENT_ENABLED(xip, DM_EVENT_WRITE) &&
 621             !(ioflags & IO_INVIS) && !eventsent)) {
 622                 int             dmflags = FILP_DELAY_FLAG(file);
 623
 624                 if (need_i_mutex)
 625                         dmflags |= DM_FLAGS_IMUX;
 626
 627                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
 628                 error = XFS_SEND_DATA(xip->i_mount, DM_EVENT_WRITE, xip,
 629                                       pos, count, dmflags, &iolock);
 630                 if (error) {
 631                         goto out_unlock_internal;
 632                 }
 633                 xfs_ilock(xip, XFS_ILOCK_EXCL);
 634                 eventsent = 1;
 635
 636                 /*
 637                  * The iolock was dropped and reacquired in XFS_SEND_DATA
 638                  * so we have to recheck the size when appending.
 639                  * We will only "goto start;" once, since having sent the
 640                  * event prevents another call to XFS_SEND_DATA, which is
 641                  * what allows the size to change in the first place.
 642                  */
 643                 if ((file->f_flags & O_APPEND) && pos != xip->i_size)
 644                         goto start;
 645         }
 646
 647         if (ioflags & IO_ISDIRECT) {
 648                 xfs_buftarg_t   *target =
 649                         XFS_IS_REALTIME_INODE(xip) ?
 650                                 mp->m_rtdev_targp : mp->m_ddev_targp;
 651
 652                 if ((pos & target->bt_smask) || (count & target->bt_smask)) {
 653                         xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
 654                         return XFS_ERROR(-EINVAL);
 655                 }
 656
 657                 if (!need_i_mutex && (mapping->nrpages || pos > xip->i_size)) {
 658                         xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
 659                         iolock = XFS_IOLOCK_EXCL;
 660                         need_i_mutex = 1;
 661                         mutex_lock(&inode->i_mutex);
 662                         xfs_ilock(xip, XFS_ILOCK_EXCL|iolock);
 663                         goto start;
 664                 }
 665         }
 666
 667         new_size = pos + count;
 668         if (new_size > xip->i_size)
 669                 xip->i_new_size = new_size;
 670
 671         /*
 672          * We're not supposed to change timestamps in readonly-mounted
 673          * filesystems.  Throw it away if anyone asks us.
 674          */
 675         if (likely(!(ioflags & IO_INVIS) &&
 676                    !mnt_want_write(file->f_path.mnt))) {
 677                 file_update_time(file);
 678                 xfs_ichgtime_fast(xip, inode,
 679                                   XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 680                 mnt_drop_write(file->f_path.mnt);
 681         }
 682
 683         /*
 684          * If the offset is beyond the size of the file, we have a couple
 685          * of things to do. First, if there is already space allocated
 686          * we need to either create holes or zero the disk or ...
 687          *
 688          * If there is a page where the previous size lands, we need
 689          * to zero it out up to the new size.
 690          */
 691
 692         if (pos > xip->i_size) {
 693                 error = xfs_zero_eof(xip, pos, xip->i_size);
 694                 if (error) {
 695                         xfs_iunlock(xip, XFS_ILOCK_EXCL);
 696                         goto out_unlock_internal;
 697                 }
 698         }
 699         xfs_iunlock(xip, XFS_ILOCK_EXCL);
 700
 701         /*
 702          * If we're writing the file then make sure to clear the
 703          * setuid and setgid bits if the process is not being run
 704          * by root.  This keeps people from modifying setuid and
 705          * setgid binaries.
 706          */
 707
 708         if (((xip->i_d.di_mode & S_ISUID) ||
 709             ((xip->i_d.di_mode & (S_ISGID | S_IXGRP)) ==
 710                 (S_ISGID | S_IXGRP))) &&
 711              !capable(CAP_FSETID)) {
 712                 error = xfs_write_clear_setuid(xip);
 713                 if (likely(!error))
 714                         error = -remove_suid(file->f_path.dentry);
 715                 if (unlikely(error)) {
 716                         goto out_unlock_internal;
 717                 }
 718         }
 719
 720 retry:
 721         /* We can write back this queue in page reclaim */
 722         current->backing_dev_info = mapping->backing_dev_info;
 723
 724         if ((ioflags & IO_ISDIRECT)) {
 725                 if (mapping->nrpages) {
 726                         WARN_ON(need_i_mutex == 0);
 727                         xfs_inval_cached_trace(xip, pos, -1,
 728                                         (pos & PAGE_CACHE_MASK), -1);
 729                         error = xfs_flushinval_pages(xip,
 730                                         (pos & PAGE_CACHE_MASK),
 731                                         -1, FI_REMAPF_LOCKED);
 732                         if (error)
 733                                 goto out_unlock_internal;
 734                 }
 735
 736                 if (need_i_mutex) {
 737                         /* demote the lock now the cached pages are gone */
 738                         xfs_ilock_demote(xip, XFS_IOLOCK_EXCL);
 739                         mutex_unlock(&inode->i_mutex);
 740
 741                         iolock = XFS_IOLOCK_SHARED;
 742                         need_i_mutex = 0;
 743                 }
 744
 745                 xfs_rw_enter_trace(XFS_DIOWR_ENTER, xip, (void *)iovp, segs,
 746                                 *offset, ioflags);
 747                 ret = generic_file_direct_write(iocb, iovp,
 748                                 &segs, pos, offset, count, ocount);
 749
 750                 /*
 751                  * direct-io write to a hole: fall through to buffered I/O
 752                  * for completing the rest of the request.
 753                  */
 754                 if (ret >= 0 && ret != count) {
 755                         XFS_STATS_ADD(xs_write_bytes, ret);
 756
 757                         pos += ret;
 758                         count -= ret;
 759
 760                         ioflags &= ~IO_ISDIRECT;
 761                         xfs_iunlock(xip, iolock);
 762                         goto relock;
 763                 }
 764         } else {
 765                 xfs_rw_enter_trace(XFS_WRITE_ENTER, xip, (void *)iovp, segs,
 766                                 *offset, ioflags);
 767                 ret = generic_file_buffered_write(iocb, iovp, segs,
 768                                 pos, offset, count, ret);
 769         }
 770
 771         current->backing_dev_info = NULL;
 772
 773         if (ret == -EIOCBQUEUED && !(ioflags & IO_ISAIO))
 774                 ret = wait_on_sync_kiocb(iocb);
 775
 776         if (ret == -ENOSPC &&
 777             DM_EVENT_ENABLED(xip, DM_EVENT_NOSPACE) && !(ioflags & IO_INVIS)) {
 778                 xfs_iunlock(xip, iolock);
 779                 if (need_i_mutex)
 780                         mutex_unlock(&inode->i_mutex);
 781                 error = XFS_SEND_NAMESP(xip->i_mount, DM_EVENT_NOSPACE, xip,
 782                                 DM_RIGHT_NULL, xip, DM_RIGHT_NULL, NULL, NULL,
 783                                 0, 0, 0); /* Delay flag intentionally  unused */
 784                 if (need_i_mutex)
 785                         mutex_lock(&inode->i_mutex);
 786                 xfs_ilock(xip, iolock);
 787                 if (error)
 788                         goto out_unlock_internal;
 789                 pos = xip->i_size;
 790                 ret = 0;
 791                 goto retry;
 792         }
 793
 794         isize = i_size_read(inode);
 795         if (unlikely(ret < 0 && ret != -EFAULT && *offset > isize))
 796                 *offset = isize;
 797
 798         if (*offset > xip->i_size) {
 799                 xfs_ilock(xip, XFS_ILOCK_EXCL);
 800                 if (*offset > xip->i_size)
 801                         xip->i_size = *offset;
 802                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
 803         }
 804
 805         error = -ret;
 806         if (ret <= 0)
 807                 goto out_unlock_internal;
 808
 809         XFS_STATS_ADD(xs_write_bytes, ret);
 810
 811         /* Handle various SYNC-type writes */
 812         if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
 813                 int error2;
 814
 815                 xfs_iunlock(xip, iolock);
 816                 if (need_i_mutex)
 817                         mutex_unlock(&inode->i_mutex);
 818                 error2 = sync_page_range(inode, mapping, pos, ret);
 819                 if (!error)
 820                         error = error2;
 821                 if (need_i_mutex)
 822                         mutex_lock(&inode->i_mutex);
 823                 xfs_ilock(xip, iolock);
 824                 error2 = xfs_write_sync_logforce(mp, 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         xfs_mount_t     *mp;
 861
 862         mp = XFS_BUF_FSPRIVATE3(bp, xfs_mount_t *);
 863         if (!XFS_FORCED_SHUTDOWN(mp)) {
 864                 xfs_buf_iorequest(bp);
 865                 return 0;
 866         } else {
 867                 xfs_buftrace("XFS__BDSTRAT IOERROR", bp);
 868                 /*
 869                  * Metadata write that didn't get logged but
 870                  * written delayed anyway. These aren't associated
 871                  * with a transaction, and can be ignored.
 872                  */
 873                 if (XFS_BUF_IODONE_FUNC(bp) == NULL &&
 874                     (XFS_BUF_ISREAD(bp)) == 0)
 875                         return (xfs_bioerror_relse(bp));
 876                 else
 877                         return (xfs_bioerror(bp));
 878         }
 879 }
 880
 881 /*
 882  * Wrapper around bdstrat so that we can stop data from going to disk in case
 883  * we are shutting down the filesystem.  Typically user data goes thru this
 884  * path; one of the exceptions is the superblock.
 885  */
 886 void
 887 xfsbdstrat(
 888         struct xfs_mount        *mp,
 889         struct xfs_buf          *bp)
 890 {
 891         ASSERT(mp);
 892         if (!XFS_FORCED_SHUTDOWN(mp)) {
 893                 xfs_buf_iorequest(bp);
 894                 return;
 895         }
 896
 897         xfs_buftrace("XFSBDSTRAT IOERROR", bp);
 898         xfs_bioerror_relse(bp);
 899 }
 900
 901 /*
 902  * If the underlying (data/log/rt) device is readonly, there are some
 903  * operations that cannot proceed.
 904  */
 905 int
 906 xfs_dev_is_read_only(
 907         xfs_mount_t             *mp,
 908         char                    *message)
 909 {
 910         if (xfs_readonly_buftarg(mp->m_ddev_targp) ||
 911             xfs_readonly_buftarg(mp->m_logdev_targp) ||
 912             (mp->m_rtdev_targp && xfs_readonly_buftarg(mp->m_rtdev_targp))) {
 913                 cmn_err(CE_NOTE,
 914                         "XFS: %s required on read-only device.", message);
 915                 cmn_err(CE_NOTE,
 916                         "XFS: write access unavailable, cannot proceed.");
 917                 return EROFS;
 918         }
 919         return 0;
 920 }