SAFE public projects git trees. - safe/jmp/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/writeback.h>
  55
  56
  57 #if defined(XFS_RW_TRACE)
  58 void
  59 xfs_rw_enter_trace(
  60         int                     tag,
  61         xfs_inode_t             *ip,
  62         void                    *data,
  63         size_t                  segs,
  64         loff_t                  offset,
  65         int                     ioflags)
  66 {
  67         if (ip->i_rwtrace == NULL)
  68                 return;
  69         ktrace_enter(ip->i_rwtrace,
  70                 (void *)(unsigned long)tag,
  71                 (void *)ip,
  72                 (void *)((unsigned long)((ip->i_d.di_size >> 32) & 0xffffffff)),
  73                 (void *)((unsigned long)(ip->i_d.di_size & 0xffffffff)),
  74                 (void *)data,
  75                 (void *)((unsigned long)segs),
  76                 (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
  77                 (void *)((unsigned long)(offset & 0xffffffff)),
  78                 (void *)((unsigned long)ioflags),
  79                 (void *)((unsigned long)((ip->i_new_size >> 32) & 0xffffffff)),
  80                 (void *)((unsigned long)(ip->i_new_size & 0xffffffff)),
  81                 (void *)((unsigned long)current_pid()),
  82                 (void *)NULL,
  83                 (void *)NULL,
  84                 (void *)NULL,
  85                 (void *)NULL);
  86 }
  87
  88 void
  89 xfs_inval_cached_trace(
  90         xfs_inode_t     *ip,
  91         xfs_off_t       offset,
  92         xfs_off_t       len,
  93         xfs_off_t       first,
  94         xfs_off_t       last)
  95 {
  96
  97         if (ip->i_rwtrace == NULL)
  98                 return;
  99         ktrace_enter(ip->i_rwtrace,
 100                 (void *)(__psint_t)XFS_INVAL_CACHED,
 101                 (void *)ip,
 102                 (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
 103                 (void *)((unsigned long)(offset & 0xffffffff)),
 104                 (void *)((unsigned long)((len >> 32) & 0xffffffff)),
 105                 (void *)((unsigned long)(len & 0xffffffff)),
 106                 (void *)((unsigned long)((first >> 32) & 0xffffffff)),
 107                 (void *)((unsigned long)(first & 0xffffffff)),
 108                 (void *)((unsigned long)((last >> 32) & 0xffffffff)),
 109                 (void *)((unsigned long)(last & 0xffffffff)),
 110                 (void *)((unsigned long)current_pid()),
 111                 (void *)NULL,
 112                 (void *)NULL,
 113                 (void *)NULL,
 114                 (void *)NULL,
 115                 (void *)NULL);
 116 }
 117 #endif
 118
 119 /*
 120  *      xfs_iozero
 121  *
 122  *      xfs_iozero clears the specified range of buffer supplied,
 123  *      and marks all the affected blocks as valid and modified.  If
 124  *      an affected block is not allocated, it will be allocated.  If
 125  *      an affected block is not completely overwritten, and is not
 126  *      valid before the operation, it will be read from disk before
 127  *      being partially zeroed.
 128  */
 129 STATIC int
 130 xfs_iozero(
 131         struct xfs_inode        *ip,    /* inode                        */
 132         loff_t                  pos,    /* offset in file               */
 133         size_t                  count)  /* size of data to zero         */
 134 {
 135         struct page             *page;
 136         struct address_space    *mapping;
 137         int                     status;
 138
 139         mapping = ip->i_vnode->i_mapping;
 140         do {
 141                 unsigned offset, bytes;
 142                 void *fsdata;
 143
 144                 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
 145                 bytes = PAGE_CACHE_SIZE - offset;
 146                 if (bytes > count)
 147                         bytes = count;
 148
 149                 status = pagecache_write_begin(NULL, mapping, pos, bytes,
 150                                         AOP_FLAG_UNINTERRUPTIBLE,
 151                                         &page, &fsdata);
 152                 if (status)
 153                         break;
 154
 155                 zero_user_page(page, offset, bytes, KM_USER0);
 156
 157                 status = pagecache_write_end(NULL, mapping, pos, bytes, bytes,
 158                                         page, fsdata);
 159                 WARN_ON(status <= 0); /* can't return less than zero! */
 160                 pos += bytes;
 161                 count -= bytes;
 162                 status = 0;
 163         } while (count);
 164
 165         return (-status);
 166 }
 167
 168 ssize_t                 /* bytes read, or (-)  error */
 169 xfs_read(
 170         xfs_inode_t             *ip,
 171         struct kiocb            *iocb,
 172         const struct iovec      *iovp,
 173         unsigned int            segs,
 174         loff_t                  *offset,
 175         int                     ioflags)
 176 {
 177         struct file             *file = iocb->ki_filp;
 178         struct inode            *inode = file->f_mapping->host;
 179         bhv_vnode_t             *vp = XFS_ITOV(ip);
 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                 bhv_vrwlock_t locktype = VRWLOCK_READ;
 232                 int dmflags = FILP_DELAY_FLAG(file) | DM_SEM_FLAG_RD(ioflags);
 233
 234                 ret = -XFS_SEND_DATA(mp, DM_EVENT_READ, vp, *offset, size,
 235                                         dmflags, &locktype);
 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 (VN_CACHED(vp))
 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         bhv_vnode_t             *vp = XFS_ITOV(ip);
 280         xfs_mount_t             *mp = ip->i_mount;
 281         ssize_t                 ret;
 282
 283         XFS_STATS_INC(xs_read_calls);
 284         if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 285                 return -EIO;
 286
 287         xfs_ilock(ip, XFS_IOLOCK_SHARED);
 288
 289         if (DM_EVENT_ENABLED(ip, DM_EVENT_READ) && !(ioflags & IO_INVIS)) {
 290                 bhv_vrwlock_t locktype = VRWLOCK_READ;
 291                 int error;
 292
 293                 error = XFS_SEND_DATA(mp, DM_EVENT_READ, vp, *ppos, count,
 294                                         FILP_DELAY_FLAG(infilp), &locktype);
 295                 if (error) {
 296                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 297                         return -error;
 298                 }
 299         }
 300         xfs_rw_enter_trace(XFS_SPLICE_READ_ENTER, ip,
 301                            pipe, count, *ppos, ioflags);
 302         ret = generic_file_splice_read(infilp, ppos, pipe, count, flags);
 303         if (ret > 0)
 304                 XFS_STATS_ADD(xs_read_bytes, ret);
 305
 306         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 307         return ret;
 308 }
 309
 310 ssize_t
 311 xfs_splice_write(
 312         xfs_inode_t             *ip,
 313         struct pipe_inode_info  *pipe,
 314         struct file             *outfilp,
 315         loff_t                  *ppos,
 316         size_t                  count,
 317         int                     flags,
 318         int                     ioflags)
 319 {
 320         bhv_vnode_t             *vp = XFS_ITOV(ip);
 321         xfs_mount_t             *mp = ip->i_mount;
 322         ssize_t                 ret;
 323         struct inode            *inode = outfilp->f_mapping->host;
 324         xfs_fsize_t             isize, new_size;
 325
 326         XFS_STATS_INC(xs_write_calls);
 327         if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 328                 return -EIO;
 329
 330         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 331
 332         if (DM_EVENT_ENABLED(ip, DM_EVENT_WRITE) && !(ioflags & IO_INVIS)) {
 333                 bhv_vrwlock_t locktype = VRWLOCK_WRITE;
 334                 int error;
 335
 336                 error = XFS_SEND_DATA(mp, DM_EVENT_WRITE, vp, *ppos, count,
 337                                         FILP_DELAY_FLAG(outfilp), &locktype);
 338                 if (error) {
 339                         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 340                         return -error;
 341                 }
 342         }
 343
 344         new_size = *ppos + count;
 345
 346         xfs_ilock(ip, XFS_ILOCK_EXCL);
 347         if (new_size > ip->i_size)
 348                 ip->i_new_size = new_size;
 349         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 350
 351         xfs_rw_enter_trace(XFS_SPLICE_WRITE_ENTER, ip,
 352                            pipe, count, *ppos, ioflags);
 353         ret = generic_file_splice_write(pipe, outfilp, ppos, count, flags);
 354         if (ret > 0)
 355                 XFS_STATS_ADD(xs_write_bytes, ret);
 356
 357         isize = i_size_read(inode);
 358         if (unlikely(ret < 0 && ret != -EFAULT && *ppos > isize))
 359                 *ppos = isize;
 360
 361         if (*ppos > ip->i_size) {
 362                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 363                 if (*ppos > ip->i_size)
 364                         ip->i_size = *ppos;
 365                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 366         }
 367
 368         if (ip->i_new_size) {
 369                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 370                 ip->i_new_size = 0;
 371                 if (ip->i_d.di_size > ip->i_size)
 372                         ip->i_d.di_size = ip->i_size;
 373                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 374         }
 375         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 376         return ret;
 377 }
 378
 379 /*
 380  * This routine is called to handle zeroing any space in the last
 381  * block of the file that is beyond the EOF.  We do this since the
 382  * size is being increased without writing anything to that block
 383  * and we don't want anyone to read the garbage on the disk.
 384  */
 385 STATIC int                              /* error (positive) */
 386 xfs_zero_last_block(
 387         xfs_inode_t     *ip,
 388         xfs_fsize_t     offset,
 389         xfs_fsize_t     isize)
 390 {
 391         xfs_fileoff_t   last_fsb;
 392         xfs_mount_t     *mp = ip->i_mount;
 393         int             nimaps;
 394         int             zero_offset;
 395         int             zero_len;
 396         int             error = 0;
 397         xfs_bmbt_irec_t imap;
 398
 399         ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE) != 0);
 400
 401         zero_offset = XFS_B_FSB_OFFSET(mp, isize);
 402         if (zero_offset == 0) {
 403                 /*
 404                  * There are no extra bytes in the last block on disk to
 405                  * zero, so return.
 406                  */
 407                 return 0;
 408         }
 409
 410         last_fsb = XFS_B_TO_FSBT(mp, isize);
 411         nimaps = 1;
 412         error = xfs_bmapi(NULL, ip, last_fsb, 1, 0, NULL, 0, &imap,
 413                           &nimaps, NULL, NULL);
 414         if (error) {
 415                 return error;
 416         }
 417         ASSERT(nimaps > 0);
 418         /*
 419          * If the block underlying isize is just a hole, then there
 420          * is nothing to zero.
 421          */
 422         if (imap.br_startblock == HOLESTARTBLOCK) {
 423                 return 0;
 424         }
 425         /*
 426          * Zero the part of the last block beyond the EOF, and write it
 427          * out sync.  We need to drop the ilock while we do this so we
 428          * don't deadlock when the buffer cache calls back to us.
 429          */
 430         xfs_iunlock(ip, XFS_ILOCK_EXCL| XFS_EXTSIZE_RD);
 431
 432         zero_len = mp->m_sb.sb_blocksize - zero_offset;
 433         if (isize + zero_len > offset)
 434                 zero_len = offset - isize;
 435         error = xfs_iozero(ip, isize, zero_len);
 436
 437         xfs_ilock(ip, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 438         ASSERT(error >= 0);
 439         return error;
 440 }
 441
 442 /*
 443  * Zero any on disk space between the current EOF and the new,
 444  * larger EOF.  This handles the normal case of zeroing the remainder
 445  * of the last block in the file and the unusual case of zeroing blocks
 446  * out beyond the size of the file.  This second case only happens
 447  * with fixed size extents and when the system crashes before the inode
 448  * size was updated but after blocks were allocated.  If fill is set,
 449  * then any holes in the range are filled and zeroed.  If not, the holes
 450  * are left alone as holes.
 451  */
 452
 453 int                                     /* error (positive) */
 454 xfs_zero_eof(
 455         xfs_inode_t     *ip,
 456         xfs_off_t       offset,         /* starting I/O offset */
 457         xfs_fsize_t     isize)          /* current inode size */
 458 {
 459         xfs_mount_t     *mp = ip->i_mount;
 460         xfs_fileoff_t   start_zero_fsb;
 461         xfs_fileoff_t   end_zero_fsb;
 462         xfs_fileoff_t   zero_count_fsb;
 463         xfs_fileoff_t   last_fsb;
 464         xfs_fileoff_t   zero_off;
 465         xfs_fsize_t     zero_len;
 466         int             nimaps;
 467         int             error = 0;
 468         xfs_bmbt_irec_t imap;
 469
 470         ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE));
 471         ASSERT(ismrlocked(&ip->i_iolock, MR_UPDATE));
 472         ASSERT(offset > isize);
 473
 474         /*
 475          * First handle zeroing the block on which isize resides.
 476          * We only zero a part of that block so it is handled specially.
 477          */
 478         error = xfs_zero_last_block(ip, offset, isize);
 479         if (error) {
 480                 ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE));
 481                 ASSERT(ismrlocked(&ip->i_iolock, MR_UPDATE));
 482                 return error;
 483         }
 484
 485         /*
 486          * Calculate the range between the new size and the old
 487          * where blocks needing to be zeroed may exist.  To get the
 488          * block where the last byte in the file currently resides,
 489          * we need to subtract one from the size and truncate back
 490          * to a block boundary.  We subtract 1 in case the size is
 491          * exactly on a block boundary.
 492          */
 493         last_fsb = isize ? XFS_B_TO_FSBT(mp, isize - 1) : (xfs_fileoff_t)-1;
 494         start_zero_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)isize);
 495         end_zero_fsb = XFS_B_TO_FSBT(mp, offset - 1);
 496         ASSERT((xfs_sfiloff_t)last_fsb < (xfs_sfiloff_t)start_zero_fsb);
 497         if (last_fsb == end_zero_fsb) {
 498                 /*
 499                  * The size was only incremented on its last block.
 500                  * We took care of that above, so just return.
 501                  */
 502                 return 0;
 503         }
 504
 505         ASSERT(start_zero_fsb <= end_zero_fsb);
 506         while (start_zero_fsb <= end_zero_fsb) {
 507                 nimaps = 1;
 508                 zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
 509                 error = xfs_bmapi(NULL, ip, start_zero_fsb, zero_count_fsb,
 510                                   0, NULL, 0, &imap, &nimaps, NULL, NULL);
 511                 if (error) {
 512                         ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE));
 513                         ASSERT(ismrlocked(&ip->i_iolock, MR_UPDATE));
 514                         return error;
 515                 }
 516                 ASSERT(nimaps > 0);
 517
 518                 if (imap.br_state == XFS_EXT_UNWRITTEN ||
 519                     imap.br_startblock == HOLESTARTBLOCK) {
 520                         /*
 521                          * This loop handles initializing pages that were
 522                          * partially initialized by the code below this
 523                          * loop. It basically zeroes the part of the page
 524                          * that sits on a hole and sets the page as P_HOLE
 525                          * and calls remapf if it is a mapped file.
 526                          */
 527                         start_zero_fsb = imap.br_startoff + imap.br_blockcount;
 528                         ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 529                         continue;
 530                 }
 531
 532                 /*
 533                  * There are blocks we need to zero.
 534                  * Drop the inode lock while we're doing the I/O.
 535                  * We'll still have the iolock to protect us.
 536                  */
 537                 xfs_iunlock(ip, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 538
 539                 zero_off = XFS_FSB_TO_B(mp, start_zero_fsb);
 540                 zero_len = XFS_FSB_TO_B(mp, imap.br_blockcount);
 541
 542                 if ((zero_off + zero_len) > offset)
 543                         zero_len = offset - zero_off;
 544
 545                 error = xfs_iozero(ip, zero_off, zero_len);
 546                 if (error) {
 547                         goto out_lock;
 548                 }
 549
 550                 start_zero_fsb = imap.br_startoff + imap.br_blockcount;
 551                 ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 552
 553                 xfs_ilock(ip, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 554         }
 555
 556         return 0;
 557
 558 out_lock:
 559         xfs_ilock(ip, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 560         ASSERT(error >= 0);
 561         return error;
 562 }
 563
 564 ssize_t                         /* bytes written, or (-) error */
 565 xfs_write(
 566         struct xfs_inode        *xip,
 567         struct kiocb            *iocb,
 568         const struct iovec      *iovp,
 569         unsigned int            nsegs,
 570         loff_t                  *offset,
 571         int                     ioflags)
 572 {
 573         struct file             *file = iocb->ki_filp;
 574         struct address_space    *mapping = file->f_mapping;
 575         struct inode            *inode = mapping->host;
 576         bhv_vnode_t             *vp = XFS_ITOV(xip);
 577         unsigned long           segs = nsegs;
 578         xfs_mount_t             *mp;
 579         ssize_t                 ret = 0, error = 0;
 580         xfs_fsize_t             isize, new_size;
 581         int                     iolock;
 582         int                     eventsent = 0;
 583         bhv_vrwlock_t           locktype;
 584         size_t                  ocount = 0, count;
 585         loff_t                  pos;
 586         int                     need_i_mutex;
 587
 588         XFS_STATS_INC(xs_write_calls);
 589
 590         error = generic_segment_checks(iovp, &segs, &ocount, VERIFY_READ);
 591         if (error)
 592                 return error;
 593
 594         count = ocount;
 595         pos = *offset;
 596
 597         if (count == 0)
 598                 return 0;
 599
 600         mp = xip->i_mount;
 601
 602         xfs_wait_for_freeze(mp, SB_FREEZE_WRITE);
 603
 604         if (XFS_FORCED_SHUTDOWN(mp))
 605                 return -EIO;
 606
 607 relock:
 608         if (ioflags & IO_ISDIRECT) {
 609                 iolock = XFS_IOLOCK_SHARED;
 610                 locktype = VRWLOCK_WRITE_DIRECT;
 611                 need_i_mutex = 0;
 612         } else {
 613                 iolock = XFS_IOLOCK_EXCL;
 614                 locktype = VRWLOCK_WRITE;
 615                 need_i_mutex = 1;
 616                 mutex_lock(&inode->i_mutex);
 617         }
 618
 619         xfs_ilock(xip, XFS_ILOCK_EXCL|iolock);
 620
 621 start:
 622         error = -generic_write_checks(file, &pos, &count,
 623                                         S_ISBLK(inode->i_mode));
 624         if (error) {
 625                 xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
 626                 goto out_unlock_mutex;
 627         }
 628
 629         if ((DM_EVENT_ENABLED(xip, DM_EVENT_WRITE) &&
 630             !(ioflags & IO_INVIS) && !eventsent)) {
 631                 int             dmflags = FILP_DELAY_FLAG(file);
 632
 633                 if (need_i_mutex)
 634                         dmflags |= DM_FLAGS_IMUX;
 635
 636                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
 637                 error = XFS_SEND_DATA(xip->i_mount, DM_EVENT_WRITE, vp,
 638                                       pos, count,
 639                                       dmflags, &locktype);
 640                 if (error) {
 641                         goto out_unlock_internal;
 642                 }
 643                 xfs_ilock(xip, XFS_ILOCK_EXCL);
 644                 eventsent = 1;
 645
 646                 /*
 647                  * The iolock was dropped and reacquired in XFS_SEND_DATA
 648                  * so we have to recheck the size when appending.
 649                  * We will only "goto start;" once, since having sent the
 650                  * event prevents another call to XFS_SEND_DATA, which is
 651                  * what allows the size to change in the first place.
 652                  */
 653                 if ((file->f_flags & O_APPEND) && pos != xip->i_size)
 654                         goto start;
 655         }
 656
 657         if (ioflags & IO_ISDIRECT) {
 658                 xfs_buftarg_t   *target =
 659                         XFS_IS_REALTIME_INODE(xip) ?
 660                                 mp->m_rtdev_targp : mp->m_ddev_targp;
 661
 662                 if ((pos & target->bt_smask) || (count & target->bt_smask)) {
 663                         xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
 664                         return XFS_ERROR(-EINVAL);
 665                 }
 666
 667                 if (!need_i_mutex && (VN_CACHED(vp) || pos > xip->i_size)) {
 668                         xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
 669                         iolock = XFS_IOLOCK_EXCL;
 670                         locktype = VRWLOCK_WRITE;
 671                         need_i_mutex = 1;
 672                         mutex_lock(&inode->i_mutex);
 673                         xfs_ilock(xip, XFS_ILOCK_EXCL|iolock);
 674                         goto start;
 675                 }
 676         }
 677
 678         new_size = pos + count;
 679         if (new_size > xip->i_size)
 680                 xip->i_new_size = new_size;
 681
 682         if (likely(!(ioflags & IO_INVIS))) {
 683                 file_update_time(file);
 684                 xfs_ichgtime_fast(xip, inode,
 685                                   XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 686         }
 687
 688         /*
 689          * If the offset is beyond the size of the file, we have a couple
 690          * of things to do. First, if there is already space allocated
 691          * we need to either create holes or zero the disk or ...
 692          *
 693          * If there is a page where the previous size lands, we need
 694          * to zero it out up to the new size.
 695          */
 696
 697         if (pos > xip->i_size) {
 698                 error = xfs_zero_eof(xip, pos, xip->i_size);
 699                 if (error) {
 700                         xfs_iunlock(xip, XFS_ILOCK_EXCL);
 701                         goto out_unlock_internal;
 702                 }
 703         }
 704         xfs_iunlock(xip, XFS_ILOCK_EXCL);
 705
 706         /*
 707          * If we're writing the file then make sure to clear the
 708          * setuid and setgid bits if the process is not being run
 709          * by root.  This keeps people from modifying setuid and
 710          * setgid binaries.
 711          */
 712
 713         if (((xip->i_d.di_mode & S_ISUID) ||
 714             ((xip->i_d.di_mode & (S_ISGID | S_IXGRP)) ==
 715                 (S_ISGID | S_IXGRP))) &&
 716              !capable(CAP_FSETID)) {
 717                 error = xfs_write_clear_setuid(xip);
 718                 if (likely(!error))
 719                         error = -remove_suid(file->f_path.dentry);
 720                 if (unlikely(error)) {
 721                         goto out_unlock_internal;
 722                 }
 723         }
 724
 725 retry:
 726         /* We can write back this queue in page reclaim */
 727         current->backing_dev_info = mapping->backing_dev_info;
 728
 729         if ((ioflags & IO_ISDIRECT)) {
 730                 if (VN_CACHED(vp)) {
 731                         WARN_ON(need_i_mutex == 0);
 732                         xfs_inval_cached_trace(xip, pos, -1,
 733                                         (pos & PAGE_CACHE_MASK), -1);
 734                         error = xfs_flushinval_pages(xip,
 735                                         (pos & PAGE_CACHE_MASK),
 736                                         -1, FI_REMAPF_LOCKED);
 737                         if (error)
 738                                 goto out_unlock_internal;
 739                 }
 740
 741                 if (need_i_mutex) {
 742                         /* demote the lock now the cached pages are gone */
 743                         xfs_ilock_demote(xip, XFS_IOLOCK_EXCL);
 744                         mutex_unlock(&inode->i_mutex);
 745
 746                         iolock = XFS_IOLOCK_SHARED;
 747                         locktype = VRWLOCK_WRITE_DIRECT;
 748                         need_i_mutex = 0;
 749                 }
 750
 751                 xfs_rw_enter_trace(XFS_DIOWR_ENTER, xip, (void *)iovp, segs,
 752                                 *offset, ioflags);
 753                 ret = generic_file_direct_write(iocb, iovp,
 754                                 &segs, pos, offset, count, ocount);
 755
 756                 /*
 757                  * direct-io write to a hole: fall through to buffered I/O
 758                  * for completing the rest of the request.
 759                  */
 760                 if (ret >= 0 && ret != count) {
 761                         XFS_STATS_ADD(xs_write_bytes, ret);
 762
 763                         pos += ret;
 764                         count -= ret;
 765
 766                         ioflags &= ~IO_ISDIRECT;
 767                         xfs_iunlock(xip, iolock);
 768                         goto relock;
 769                 }
 770         } else {
 771                 xfs_rw_enter_trace(XFS_WRITE_ENTER, xip, (void *)iovp, segs,
 772                                 *offset, ioflags);
 773                 ret = generic_file_buffered_write(iocb, iovp, segs,
 774                                 pos, offset, count, ret);
 775         }
 776
 777         current->backing_dev_info = NULL;
 778
 779         if (ret == -EIOCBQUEUED && !(ioflags & IO_ISAIO))
 780                 ret = wait_on_sync_kiocb(iocb);
 781
 782         if (ret == -ENOSPC &&
 783             DM_EVENT_ENABLED(xip, DM_EVENT_NOSPACE) && !(ioflags & IO_INVIS)) {
 784                 xfs_rwunlock(xip, locktype);
 785                 if (need_i_mutex)
 786                         mutex_unlock(&inode->i_mutex);
 787                 error = XFS_SEND_NAMESP(xip->i_mount, DM_EVENT_NOSPACE, vp,
 788                                 DM_RIGHT_NULL, vp, DM_RIGHT_NULL, NULL, NULL,
 789                                 0, 0, 0); /* Delay flag intentionally  unused */
 790                 if (need_i_mutex)
 791                         mutex_lock(&inode->i_mutex);
 792                 xfs_rwlock(xip, locktype);
 793                 if (error)
 794                         goto out_unlock_internal;
 795                 pos = xip->i_size;
 796                 ret = 0;
 797                 goto retry;
 798         }
 799
 800         isize = i_size_read(inode);
 801         if (unlikely(ret < 0 && ret != -EFAULT && *offset > isize))
 802                 *offset = isize;
 803
 804         if (*offset > xip->i_size) {
 805                 xfs_ilock(xip, XFS_ILOCK_EXCL);
 806                 if (*offset > xip->i_size)
 807                         xip->i_size = *offset;
 808                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
 809         }
 810
 811         error = -ret;
 812         if (ret <= 0)
 813                 goto out_unlock_internal;
 814
 815         XFS_STATS_ADD(xs_write_bytes, ret);
 816
 817         /* Handle various SYNC-type writes */
 818         if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
 819                 int error2;
 820                 xfs_rwunlock(xip, locktype);
 821                 if (need_i_mutex)
 822                         mutex_unlock(&inode->i_mutex);
 823                 error2 = sync_page_range(inode, mapping, pos, ret);
 824                 if (!error)
 825                         error = error2;
 826                 if (need_i_mutex)
 827                         mutex_lock(&inode->i_mutex);
 828                 xfs_rwlock(xip, locktype);
 829                 error2 = xfs_write_sync_logforce(mp, xip);
 830                 if (!error)
 831                         error = error2;
 832         }
 833
 834  out_unlock_internal:
 835         if (xip->i_new_size) {
 836                 xfs_ilock(xip, XFS_ILOCK_EXCL);
 837                 xip->i_new_size = 0;
 838                 /*
 839                  * If this was a direct or synchronous I/O that failed (such
 840                  * as ENOSPC) then part of the I/O may have been written to
 841                  * disk before the error occured.  In this case the on-disk
 842                  * file size may have been adjusted beyond the in-memory file
 843                  * size and now needs to be truncated back.
 844                  */
 845                 if (xip->i_d.di_size > xip->i_size)
 846                         xip->i_d.di_size = xip->i_size;
 847                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
 848         }
 849         xfs_rwunlock(xip, locktype);
 850  out_unlock_mutex:
 851         if (need_i_mutex)
 852                 mutex_unlock(&inode->i_mutex);
 853         return -error;
 854 }
 855
 856 /*
 857  * All xfs metadata buffers except log state machine buffers
 858  * get this attached as their b_bdstrat callback function.
 859  * This is so that we can catch a buffer
 860  * after prematurely unpinning it to forcibly shutdown the filesystem.
 861  */
 862 int
 863 xfs_bdstrat_cb(struct xfs_buf *bp)
 864 {
 865         xfs_mount_t     *mp;
 866
 867         mp = XFS_BUF_FSPRIVATE3(bp, xfs_mount_t *);
 868         if (!XFS_FORCED_SHUTDOWN(mp)) {
 869                 xfs_buf_iorequest(bp);
 870                 return 0;
 871         } else {
 872                 xfs_buftrace("XFS__BDSTRAT IOERROR", bp);
 873                 /*
 874                  * Metadata write that didn't get logged but
 875                  * written delayed anyway. These aren't associated
 876                  * with a transaction, and can be ignored.
 877                  */
 878                 if (XFS_BUF_IODONE_FUNC(bp) == NULL &&
 879                     (XFS_BUF_ISREAD(bp)) == 0)
 880                         return (xfs_bioerror_relse(bp));
 881                 else
 882                         return (xfs_bioerror(bp));
 883         }
 884 }
 885
 886 /*
 887  * Wrapper around bdstrat so that we can stop data
 888  * from going to disk in case we are shutting down the filesystem.
 889  * Typically user data goes thru this path; one of the exceptions
 890  * is the superblock.
 891  */
 892 int
 893 xfsbdstrat(
 894         struct xfs_mount        *mp,
 895         struct xfs_buf          *bp)
 896 {
 897         ASSERT(mp);
 898         if (!XFS_FORCED_SHUTDOWN(mp)) {
 899                 /* Grio redirection would go here
 900                  * if (XFS_BUF_IS_GRIO(bp)) {
 901                  */
 902
 903                 xfs_buf_iorequest(bp);
 904                 return 0;
 905         }
 906
 907         xfs_buftrace("XFSBDSTRAT IOERROR", bp);
 908         return (xfs_bioerror_relse(bp));
 909 }
 910
 911 /*
 912  * If the underlying (data/log/rt) device is readonly, there are some
 913  * operations that cannot proceed.
 914  */
 915 int
 916 xfs_dev_is_read_only(
 917         xfs_mount_t             *mp,
 918         char                    *message)
 919 {
 920         if (xfs_readonly_buftarg(mp->m_ddev_targp) ||
 921             xfs_readonly_buftarg(mp->m_logdev_targp) ||
 922             (mp->m_rtdev_targp && xfs_readonly_buftarg(mp->m_rtdev_targp))) {
 923                 cmn_err(CE_NOTE,
 924                         "XFS: %s required on read-only device.", message);
 925                 cmn_err(CE_NOTE,
 926                         "XFS: write access unavailable, cannot proceed.");
 927                 return EROFS;
 928         }
 929         return 0;
 930 }