git.oblomov.eu 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_dir.h"
  27 #include "xfs_dir2.h"
  28 #include "xfs_alloc.h"
  29 #include "xfs_dmapi.h"
  30 #include "xfs_quota.h"
  31 #include "xfs_mount.h"
  32 #include "xfs_bmap_btree.h"
  33 #include "xfs_alloc_btree.h"
  34 #include "xfs_ialloc_btree.h"
  35 #include "xfs_dir_sf.h"
  36 #include "xfs_dir2_sf.h"
  37 #include "xfs_attr_sf.h"
  38 #include "xfs_dinode.h"
  39 #include "xfs_inode.h"
  40 #include "xfs_bmap.h"
  41 #include "xfs_btree.h"
  42 #include "xfs_ialloc.h"
  43 #include "xfs_rtalloc.h"
  44 #include "xfs_error.h"
  45 #include "xfs_itable.h"
  46 #include "xfs_rw.h"
  47 #include "xfs_acl.h"
  48 #include "xfs_cap.h"
  49 #include "xfs_mac.h"
  50 #include "xfs_attr.h"
  51 #include "xfs_inode_item.h"
  52 #include "xfs_buf_item.h"
  53 #include "xfs_utils.h"
  54 #include "xfs_iomap.h"
  55
  56 #include <linux/capability.h>
  57 #include <linux/writeback.h>
  58
  59
  60 #if defined(XFS_RW_TRACE)
  61 void
  62 xfs_rw_enter_trace(
  63         int                     tag,
  64         xfs_iocore_t            *io,
  65         void                    *data,
  66         size_t                  segs,
  67         loff_t                  offset,
  68         int                     ioflags)
  69 {
  70         xfs_inode_t     *ip = XFS_IO_INODE(io);
  71
  72         if (ip->i_rwtrace == NULL)
  73                 return;
  74         ktrace_enter(ip->i_rwtrace,
  75                 (void *)(unsigned long)tag,
  76                 (void *)ip,
  77                 (void *)((unsigned long)((ip->i_d.di_size >> 32) & 0xffffffff)),
  78                 (void *)((unsigned long)(ip->i_d.di_size & 0xffffffff)),
  79                 (void *)data,
  80                 (void *)((unsigned long)segs),
  81                 (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
  82                 (void *)((unsigned long)(offset & 0xffffffff)),
  83                 (void *)((unsigned long)ioflags),
  84                 (void *)((unsigned long)((io->io_new_size >> 32) & 0xffffffff)),
  85                 (void *)((unsigned long)(io->io_new_size & 0xffffffff)),
  86                 (void *)NULL,
  87                 (void *)NULL,
  88                 (void *)NULL,
  89                 (void *)NULL,
  90                 (void *)NULL);
  91 }
  92
  93 void
  94 xfs_inval_cached_trace(
  95         xfs_iocore_t    *io,
  96         xfs_off_t       offset,
  97         xfs_off_t       len,
  98         xfs_off_t       first,
  99         xfs_off_t       last)
 100 {
 101         xfs_inode_t     *ip = XFS_IO_INODE(io);
 102
 103         if (ip->i_rwtrace == NULL)
 104                 return;
 105         ktrace_enter(ip->i_rwtrace,
 106                 (void *)(__psint_t)XFS_INVAL_CACHED,
 107                 (void *)ip,
 108                 (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
 109                 (void *)((unsigned long)(offset & 0xffffffff)),
 110                 (void *)((unsigned long)((len >> 32) & 0xffffffff)),
 111                 (void *)((unsigned long)(len & 0xffffffff)),
 112                 (void *)((unsigned long)((first >> 32) & 0xffffffff)),
 113                 (void *)((unsigned long)(first & 0xffffffff)),
 114                 (void *)((unsigned long)((last >> 32) & 0xffffffff)),
 115                 (void *)((unsigned long)(last & 0xffffffff)),
 116                 (void *)NULL,
 117                 (void *)NULL,
 118                 (void *)NULL,
 119                 (void *)NULL,
 120                 (void *)NULL,
 121                 (void *)NULL);
 122 }
 123 #endif
 124
 125 /*
 126  *      xfs_iozero
 127  *
 128  *      xfs_iozero clears the specified range of buffer supplied,
 129  *      and marks all the affected blocks as valid and modified.  If
 130  *      an affected block is not allocated, it will be allocated.  If
 131  *      an affected block is not completely overwritten, and is not
 132  *      valid before the operation, it will be read from disk before
 133  *      being partially zeroed.
 134  */
 135 STATIC int
 136 xfs_iozero(
 137         struct inode            *ip,    /* inode                        */
 138         loff_t                  pos,    /* offset in file               */
 139         size_t                  count,  /* size of data to zero         */
 140         loff_t                  end_size)       /* max file size to set */
 141 {
 142         unsigned                bytes;
 143         struct page             *page;
 144         struct address_space    *mapping;
 145         char                    *kaddr;
 146         int                     status;
 147
 148         mapping = ip->i_mapping;
 149         do {
 150                 unsigned long index, offset;
 151
 152                 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
 153                 index = pos >> PAGE_CACHE_SHIFT;
 154                 bytes = PAGE_CACHE_SIZE - offset;
 155                 if (bytes > count)
 156                         bytes = count;
 157
 158                 status = -ENOMEM;
 159                 page = grab_cache_page(mapping, index);
 160                 if (!page)
 161                         break;
 162
 163                 kaddr = kmap(page);
 164                 status = mapping->a_ops->prepare_write(NULL, page, offset,
 165                                                         offset + bytes);
 166                 if (status) {
 167                         goto unlock;
 168                 }
 169
 170                 memset((void *) (kaddr + offset), 0, bytes);
 171                 flush_dcache_page(page);
 172                 status = mapping->a_ops->commit_write(NULL, page, offset,
 173                                                         offset + bytes);
 174                 if (!status) {
 175                         pos += bytes;
 176                         count -= bytes;
 177                         if (pos > i_size_read(ip))
 178                                 i_size_write(ip, pos < end_size ? pos : end_size);
 179                 }
 180
 181 unlock:
 182                 kunmap(page);
 183                 unlock_page(page);
 184                 page_cache_release(page);
 185                 if (status)
 186                         break;
 187         } while (count);
 188
 189         return (-status);
 190 }
 191
 192 ssize_t                 /* bytes read, or (-)  error */
 193 xfs_read(
 194         bhv_desc_t              *bdp,
 195         struct kiocb            *iocb,
 196         const struct iovec      *iovp,
 197         unsigned int            segs,
 198         loff_t                  *offset,
 199         int                     ioflags,
 200         cred_t                  *credp)
 201 {
 202         struct file             *file = iocb->ki_filp;
 203         struct inode            *inode = file->f_mapping->host;
 204         size_t                  size = 0;
 205         ssize_t                 ret;
 206         xfs_fsize_t             n;
 207         xfs_inode_t             *ip;
 208         xfs_mount_t             *mp;
 209         vnode_t                 *vp;
 210         unsigned long           seg;
 211
 212         ip = XFS_BHVTOI(bdp);
 213         vp = BHV_TO_VNODE(bdp);
 214         mp = ip->i_mount;
 215
 216         XFS_STATS_INC(xs_read_calls);
 217
 218         /* START copy & waste from filemap.c */
 219         for (seg = 0; seg < segs; seg++) {
 220                 const struct iovec *iv = &iovp[seg];
 221
 222                 /*
 223                  * If any segment has a negative length, or the cumulative
 224                  * length ever wraps negative then return -EINVAL.
 225                  */
 226                 size += iv->iov_len;
 227                 if (unlikely((ssize_t)(size|iv->iov_len) < 0))
 228                         return XFS_ERROR(-EINVAL);
 229         }
 230         /* END copy & waste from filemap.c */
 231
 232         if (unlikely(ioflags & IO_ISDIRECT)) {
 233                 xfs_buftarg_t   *target =
 234                         (ip->i_d.di_flags & XFS_DIFLAG_REALTIME) ?
 235                                 mp->m_rtdev_targp : mp->m_ddev_targp;
 236                 if ((*offset & target->pbr_smask) ||
 237                     (size & target->pbr_smask)) {
 238                         if (*offset == ip->i_d.di_size) {
 239                                 return (0);
 240                         }
 241                         return -XFS_ERROR(EINVAL);
 242                 }
 243         }
 244
 245         n = XFS_MAXIOFFSET(mp) - *offset;
 246         if ((n <= 0) || (size == 0))
 247                 return 0;
 248
 249         if (n < size)
 250                 size = n;
 251
 252         if (XFS_FORCED_SHUTDOWN(mp)) {
 253                 return -EIO;
 254         }
 255
 256         if (unlikely(ioflags & IO_ISDIRECT))
 257                 down(&inode->i_sem);
 258         xfs_ilock(ip, XFS_IOLOCK_SHARED);
 259
 260         if (DM_EVENT_ENABLED(vp->v_vfsp, ip, DM_EVENT_READ) &&
 261             !(ioflags & IO_INVIS)) {
 262                 vrwlock_t locktype = VRWLOCK_READ;
 263                 int dmflags = FILP_DELAY_FLAG(file) | DM_SEM_FLAG_RD(ioflags);
 264
 265                 ret = -XFS_SEND_DATA(mp, DM_EVENT_READ,
 266                                         BHV_TO_VNODE(bdp), *offset, size,
 267                                         dmflags, &locktype);
 268                 if (ret) {
 269                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 270                         goto unlock_isem;
 271                 }
 272         }
 273
 274         xfs_rw_enter_trace(XFS_READ_ENTER, &ip->i_iocore,
 275                                 (void *)iovp, segs, *offset, ioflags);
 276         ret = __generic_file_aio_read(iocb, iovp, segs, offset);
 277         if (ret == -EIOCBQUEUED && !(ioflags & IO_ISAIO))
 278                 ret = wait_on_sync_kiocb(iocb);
 279         if (ret > 0)
 280                 XFS_STATS_ADD(xs_read_bytes, ret);
 281
 282         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 283
 284         if (likely(!(ioflags & IO_INVIS)))
 285                 xfs_ichgtime_fast(ip, inode, XFS_ICHGTIME_ACC);
 286
 287 unlock_isem:
 288         if (unlikely(ioflags & IO_ISDIRECT))
 289                 up(&inode->i_sem);
 290         return ret;
 291 }
 292
 293 ssize_t
 294 xfs_sendfile(
 295         bhv_desc_t              *bdp,
 296         struct file             *filp,
 297         loff_t                  *offset,
 298         int                     ioflags,
 299         size_t                  count,
 300         read_actor_t            actor,
 301         void                    *target,
 302         cred_t                  *credp)
 303 {
 304         ssize_t                 ret;
 305         xfs_fsize_t             n;
 306         xfs_inode_t             *ip;
 307         xfs_mount_t             *mp;
 308         vnode_t                 *vp;
 309
 310         ip = XFS_BHVTOI(bdp);
 311         vp = BHV_TO_VNODE(bdp);
 312         mp = ip->i_mount;
 313
 314         XFS_STATS_INC(xs_read_calls);
 315
 316         n = XFS_MAXIOFFSET(mp) - *offset;
 317         if ((n <= 0) || (count == 0))
 318                 return 0;
 319
 320         if (n < count)
 321                 count = n;
 322
 323         if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 324                 return -EIO;
 325
 326         xfs_ilock(ip, XFS_IOLOCK_SHARED);
 327
 328         if (DM_EVENT_ENABLED(vp->v_vfsp, ip, DM_EVENT_READ) &&
 329             (!(ioflags & IO_INVIS))) {
 330                 vrwlock_t locktype = VRWLOCK_READ;
 331                 int error;
 332
 333                 error = XFS_SEND_DATA(mp, DM_EVENT_READ, BHV_TO_VNODE(bdp), *offset, count,
 334                                       FILP_DELAY_FLAG(filp), &locktype);
 335                 if (error) {
 336                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 337                         return -error;
 338                 }
 339         }
 340         xfs_rw_enter_trace(XFS_SENDFILE_ENTER, &ip->i_iocore,
 341                    (void *)(unsigned long)target, count, *offset, ioflags);
 342         ret = generic_file_sendfile(filp, offset, count, actor, target);
 343
 344         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 345
 346         if (ret > 0)
 347                 XFS_STATS_ADD(xs_read_bytes, ret);
 348
 349         if (likely(!(ioflags & IO_INVIS)))
 350                 xfs_ichgtime_fast(ip, LINVFS_GET_IP(vp), XFS_ICHGTIME_ACC);
 351
 352         return ret;
 353 }
 354
 355 /*
 356  * This routine is called to handle zeroing any space in the last
 357  * block of the file that is beyond the EOF.  We do this since the
 358  * size is being increased without writing anything to that block
 359  * and we don't want anyone to read the garbage on the disk.
 360  */
 361 STATIC int                              /* error (positive) */
 362 xfs_zero_last_block(
 363         struct inode    *ip,
 364         xfs_iocore_t    *io,
 365         xfs_off_t       offset,
 366         xfs_fsize_t     isize,
 367         xfs_fsize_t     end_size)
 368 {
 369         xfs_fileoff_t   last_fsb;
 370         xfs_mount_t     *mp;
 371         int             nimaps;
 372         int             zero_offset;
 373         int             zero_len;
 374         int             isize_fsb_offset;
 375         int             error = 0;
 376         xfs_bmbt_irec_t imap;
 377         loff_t          loff;
 378         size_t          lsize;
 379
 380         ASSERT(ismrlocked(io->io_lock, MR_UPDATE) != 0);
 381         ASSERT(offset > isize);
 382
 383         mp = io->io_mount;
 384
 385         isize_fsb_offset = XFS_B_FSB_OFFSET(mp, isize);
 386         if (isize_fsb_offset == 0) {
 387                 /*
 388                  * There are no extra bytes in the last block on disk to
 389                  * zero, so return.
 390                  */
 391                 return 0;
 392         }
 393
 394         last_fsb = XFS_B_TO_FSBT(mp, isize);
 395         nimaps = 1;
 396         error = XFS_BMAPI(mp, NULL, io, last_fsb, 1, 0, NULL, 0, &imap,
 397                           &nimaps, NULL);
 398         if (error) {
 399                 return error;
 400         }
 401         ASSERT(nimaps > 0);
 402         /*
 403          * If the block underlying isize is just a hole, then there
 404          * is nothing to zero.
 405          */
 406         if (imap.br_startblock == HOLESTARTBLOCK) {
 407                 return 0;
 408         }
 409         /*
 410          * Zero the part of the last block beyond the EOF, and write it
 411          * out sync.  We need to drop the ilock while we do this so we
 412          * don't deadlock when the buffer cache calls back to us.
 413          */
 414         XFS_IUNLOCK(mp, io, XFS_ILOCK_EXCL| XFS_EXTSIZE_RD);
 415         loff = XFS_FSB_TO_B(mp, last_fsb);
 416         lsize = XFS_FSB_TO_B(mp, 1);
 417
 418         zero_offset = isize_fsb_offset;
 419         zero_len = mp->m_sb.sb_blocksize - isize_fsb_offset;
 420
 421         error = xfs_iozero(ip, loff + zero_offset, zero_len, end_size);
 422
 423         XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 424         ASSERT(error >= 0);
 425         return error;
 426 }
 427
 428 /*
 429  * Zero any on disk space between the current EOF and the new,
 430  * larger EOF.  This handles the normal case of zeroing the remainder
 431  * of the last block in the file and the unusual case of zeroing blocks
 432  * out beyond the size of the file.  This second case only happens
 433  * with fixed size extents and when the system crashes before the inode
 434  * size was updated but after blocks were allocated.  If fill is set,
 435  * then any holes in the range are filled and zeroed.  If not, the holes
 436  * are left alone as holes.
 437  */
 438
 439 int                                     /* error (positive) */
 440 xfs_zero_eof(
 441         vnode_t         *vp,
 442         xfs_iocore_t    *io,
 443         xfs_off_t       offset,         /* starting I/O offset */
 444         xfs_fsize_t     isize,          /* current inode size */
 445         xfs_fsize_t     end_size)       /* terminal inode size */
 446 {
 447         struct inode    *ip = LINVFS_GET_IP(vp);
 448         xfs_fileoff_t   start_zero_fsb;
 449         xfs_fileoff_t   end_zero_fsb;
 450         xfs_fileoff_t   prev_zero_fsb;
 451         xfs_fileoff_t   zero_count_fsb;
 452         xfs_fileoff_t   last_fsb;
 453         xfs_extlen_t    buf_len_fsb;
 454         xfs_extlen_t    prev_zero_count;
 455         xfs_mount_t     *mp;
 456         int             nimaps;
 457         int             error = 0;
 458         xfs_bmbt_irec_t imap;
 459         loff_t          loff;
 460         size_t          lsize;
 461
 462         ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
 463         ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));
 464
 465         mp = io->io_mount;
 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, io, offset, isize, end_size);
 472         if (error) {
 473                 ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
 474                 ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));
 475                 return error;
 476         }
 477
 478         /*
 479          * Calculate the range between the new size and the old
 480          * where blocks needing to be zeroed may exist.  To get the
 481          * block where the last byte in the file currently resides,
 482          * we need to subtract one from the size and truncate back
 483          * to a block boundary.  We subtract 1 in case the size is
 484          * exactly on a block boundary.
 485          */
 486         last_fsb = isize ? XFS_B_TO_FSBT(mp, isize - 1) : (xfs_fileoff_t)-1;
 487         start_zero_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)isize);
 488         end_zero_fsb = XFS_B_TO_FSBT(mp, offset - 1);
 489         ASSERT((xfs_sfiloff_t)last_fsb < (xfs_sfiloff_t)start_zero_fsb);
 490         if (last_fsb == end_zero_fsb) {
 491                 /*
 492                  * The size was only incremented on its last block.
 493                  * We took care of that above, so just return.
 494                  */
 495                 return 0;
 496         }
 497
 498         ASSERT(start_zero_fsb <= end_zero_fsb);
 499         prev_zero_fsb = NULLFILEOFF;
 500         prev_zero_count = 0;
 501         while (start_zero_fsb <= end_zero_fsb) {
 502                 nimaps = 1;
 503                 zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
 504                 error = XFS_BMAPI(mp, NULL, io, start_zero_fsb, zero_count_fsb,
 505                                   0, NULL, 0, &imap, &nimaps, NULL);
 506                 if (error) {
 507                         ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
 508                         ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));
 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                         prev_zero_fsb = NULLFILEOFF;
 523                         prev_zero_count = 0;
 524                         start_zero_fsb = imap.br_startoff +
 525                                          imap.br_blockcount;
 526                         ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 527                         continue;
 528                 }
 529
 530                 /*
 531                  * There are blocks in the range requested.
 532                  * Zero them a single write at a time.  We actually
 533                  * don't zero the entire range returned if it is
 534                  * too big and simply loop around to get the rest.
 535                  * That is not the most efficient thing to do, but it
 536                  * is simple and this path should not be exercised often.
 537                  */
 538                 buf_len_fsb = XFS_FILBLKS_MIN(imap.br_blockcount,
 539                                               mp->m_writeio_blocks << 8);
 540                 /*
 541                  * Drop the inode lock while we're doing the I/O.
 542                  * We'll still have the iolock to protect us.
 543                  */
 544                 XFS_IUNLOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 545
 546                 loff = XFS_FSB_TO_B(mp, start_zero_fsb);
 547                 lsize = XFS_FSB_TO_B(mp, buf_len_fsb);
 548
 549                 error = xfs_iozero(ip, loff, lsize, end_size);
 550
 551                 if (error) {
 552                         goto out_lock;
 553                 }
 554
 555                 prev_zero_fsb = start_zero_fsb;
 556                 prev_zero_count = buf_len_fsb;
 557                 start_zero_fsb = imap.br_startoff + buf_len_fsb;
 558                 ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 559
 560                 XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 561         }
 562
 563         return 0;
 564
 565 out_lock:
 566
 567         XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 568         ASSERT(error >= 0);
 569         return error;
 570 }
 571
 572 ssize_t                         /* bytes written, or (-) error */
 573 xfs_write(
 574         bhv_desc_t              *bdp,
 575         struct kiocb            *iocb,
 576         const struct iovec      *iovp,
 577         unsigned int            nsegs,
 578         loff_t                  *offset,
 579         int                     ioflags,
 580         cred_t                  *credp)
 581 {
 582         struct file             *file = iocb->ki_filp;
 583         struct address_space    *mapping = file->f_mapping;
 584         struct inode            *inode = mapping->host;
 585         unsigned long           segs = nsegs;
 586         xfs_inode_t             *xip;
 587         xfs_mount_t             *mp;
 588         ssize_t                 ret = 0, error = 0;
 589         xfs_fsize_t             isize, new_size;
 590         xfs_iocore_t            *io;
 591         vnode_t                 *vp;
 592         unsigned long           seg;
 593         int                     iolock;
 594         int                     eventsent = 0;
 595         vrwlock_t               locktype;
 596         size_t                  ocount = 0, count;
 597         loff_t                  pos;
 598         int                     need_isem = 1, need_flush = 0;
 599
 600         XFS_STATS_INC(xs_write_calls);
 601
 602         vp = BHV_TO_VNODE(bdp);
 603         xip = XFS_BHVTOI(bdp);
 604
 605         for (seg = 0; seg < segs; seg++) {
 606                 const struct iovec *iv = &iovp[seg];
 607
 608                 /*
 609                  * If any segment has a negative length, or the cumulative
 610                  * length ever wraps negative then return -EINVAL.
 611                  */
 612                 ocount += iv->iov_len;
 613                 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
 614                         return -EINVAL;
 615                 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
 616                         continue;
 617                 if (seg == 0)
 618                         return -EFAULT;
 619                 segs = seg;
 620                 ocount -= iv->iov_len;  /* This segment is no good */
 621                 break;
 622         }
 623
 624         count = ocount;
 625         pos = *offset;
 626
 627         if (count == 0)
 628                 return 0;
 629
 630         io = &xip->i_iocore;
 631         mp = io->io_mount;
 632
 633         if (XFS_FORCED_SHUTDOWN(mp))
 634                 return -EIO;
 635
 636         fs_check_frozen(vp->v_vfsp, SB_FREEZE_WRITE);
 637
 638         if (ioflags & IO_ISDIRECT) {
 639                 xfs_buftarg_t   *target =
 640                         (xip->i_d.di_flags & XFS_DIFLAG_REALTIME) ?
 641                                 mp->m_rtdev_targp : mp->m_ddev_targp;
 642
 643                 if ((pos & target->pbr_smask) || (count & target->pbr_smask))
 644                         return XFS_ERROR(-EINVAL);
 645
 646                 if (!VN_CACHED(vp) && pos < i_size_read(inode))
 647                         need_isem = 0;
 648
 649                 if (VN_CACHED(vp))
 650                         need_flush = 1;
 651         }
 652
 653 relock:
 654         if (need_isem) {
 655                 iolock = XFS_IOLOCK_EXCL;
 656                 locktype = VRWLOCK_WRITE;
 657
 658                 down(&inode->i_sem);
 659         } else {
 660                 iolock = XFS_IOLOCK_SHARED;
 661                 locktype = VRWLOCK_WRITE_DIRECT;
 662         }
 663
 664         xfs_ilock(xip, XFS_ILOCK_EXCL|iolock);
 665
 666         isize = i_size_read(inode);
 667
 668         if (file->f_flags & O_APPEND)
 669                 *offset = isize;
 670
 671 start:
 672         error = -generic_write_checks(file, &pos, &count,
 673                                         S_ISBLK(inode->i_mode));
 674         if (error) {
 675                 xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
 676                 goto out_unlock_isem;
 677         }
 678
 679         new_size = pos + count;
 680         if (new_size > isize)
 681                 io->io_new_size = new_size;
 682
 683         if ((DM_EVENT_ENABLED(vp->v_vfsp, xip, DM_EVENT_WRITE) &&
 684             !(ioflags & IO_INVIS) && !eventsent)) {
 685                 loff_t          savedsize = pos;
 686                 int             dmflags = FILP_DELAY_FLAG(file);
 687
 688                 if (need_isem)
 689                         dmflags |= DM_FLAGS_ISEM;
 690
 691                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
 692                 error = XFS_SEND_DATA(xip->i_mount, DM_EVENT_WRITE, vp,
 693                                       pos, count,
 694                                       dmflags, &locktype);
 695                 if (error) {
 696                         xfs_iunlock(xip, iolock);
 697                         goto out_unlock_isem;
 698                 }
 699                 xfs_ilock(xip, XFS_ILOCK_EXCL);
 700                 eventsent = 1;
 701
 702                 /*
 703                  * The iolock was dropped and reaquired in XFS_SEND_DATA
 704                  * so we have to recheck the size when appending.
 705                  * We will only "goto start;" once, since having sent the
 706                  * event prevents another call to XFS_SEND_DATA, which is
 707                  * what allows the size to change in the first place.
 708                  */
 709                 if ((file->f_flags & O_APPEND) && savedsize != isize) {
 710                         pos = isize = xip->i_d.di_size;
 711                         goto start;
 712                 }
 713         }
 714
 715         if (likely(!(ioflags & IO_INVIS))) {
 716                 inode_update_time(inode, 1);
 717                 xfs_ichgtime_fast(xip, inode,
 718                                   XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 719         }
 720
 721         /*
 722          * If the offset is beyond the size of the file, we have a couple
 723          * of things to do. First, if there is already space allocated
 724          * we need to either create holes or zero the disk or ...
 725          *
 726          * If there is a page where the previous size lands, we need
 727          * to zero it out up to the new size.
 728          */
 729
 730         if (pos > isize) {
 731                 error = xfs_zero_eof(BHV_TO_VNODE(bdp), io, pos,
 732                                         isize, pos + count);
 733                 if (error) {
 734                         xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
 735                         goto out_unlock_isem;
 736                 }
 737         }
 738         xfs_iunlock(xip, XFS_ILOCK_EXCL);
 739
 740         /*
 741          * If we're writing the file then make sure to clear the
 742          * setuid and setgid bits if the process is not being run
 743          * by root.  This keeps people from modifying setuid and
 744          * setgid binaries.
 745          */
 746
 747         if (((xip->i_d.di_mode & S_ISUID) ||
 748             ((xip->i_d.di_mode & (S_ISGID | S_IXGRP)) ==
 749                 (S_ISGID | S_IXGRP))) &&
 750              !capable(CAP_FSETID)) {
 751                 error = xfs_write_clear_setuid(xip);
 752                 if (likely(!error))
 753                         error = -remove_suid(file->f_dentry);
 754                 if (unlikely(error)) {
 755                         xfs_iunlock(xip, iolock);
 756                         goto out_unlock_isem;
 757                 }
 758         }
 759
 760 retry:
 761         /* We can write back this queue in page reclaim */
 762         current->backing_dev_info = mapping->backing_dev_info;
 763
 764         if ((ioflags & IO_ISDIRECT)) {
 765                 if (need_flush) {
 766                         xfs_inval_cached_trace(io, pos, -1,
 767                                         ctooff(offtoct(pos)), -1);
 768                         VOP_FLUSHINVAL_PAGES(vp, ctooff(offtoct(pos)),
 769                                         -1, FI_REMAPF_LOCKED);
 770                 }
 771
 772                 if (need_isem) {
 773                         /* demote the lock now the cached pages are gone */
 774                         XFS_ILOCK_DEMOTE(mp, io, XFS_IOLOCK_EXCL);
 775                         up(&inode->i_sem);
 776
 777                         iolock = XFS_IOLOCK_SHARED;
 778                         locktype = VRWLOCK_WRITE_DIRECT;
 779                         need_isem = 0;
 780                 }
 781
 782                 xfs_rw_enter_trace(XFS_DIOWR_ENTER, io, (void *)iovp, segs,
 783                                 *offset, ioflags);
 784                 ret = generic_file_direct_write(iocb, iovp,
 785                                 &segs, pos, offset, count, ocount);
 786
 787                 /*
 788                  * direct-io write to a hole: fall through to buffered I/O
 789                  * for completing the rest of the request.
 790                  */
 791                 if (ret >= 0 && ret != count) {
 792                         XFS_STATS_ADD(xs_write_bytes, ret);
 793
 794                         pos += ret;
 795                         count -= ret;
 796
 797                         need_isem = 1;
 798                         ioflags &= ~IO_ISDIRECT;
 799                         xfs_iunlock(xip, iolock);
 800                         goto relock;
 801                 }
 802         } else {
 803                 xfs_rw_enter_trace(XFS_WRITE_ENTER, io, (void *)iovp, segs,
 804                                 *offset, ioflags);
 805                 ret = generic_file_buffered_write(iocb, iovp, segs,
 806                                 pos, offset, count, ret);
 807         }
 808
 809         current->backing_dev_info = NULL;
 810
 811         if (ret == -EIOCBQUEUED && !(ioflags & IO_ISAIO))
 812                 ret = wait_on_sync_kiocb(iocb);
 813
 814         if ((ret == -ENOSPC) &&
 815             DM_EVENT_ENABLED(vp->v_vfsp, xip, DM_EVENT_NOSPACE) &&
 816             !(ioflags & IO_INVIS)) {
 817
 818                 xfs_rwunlock(bdp, locktype);
 819                 if (need_isem)
 820                         up(&inode->i_sem);
 821                 error = XFS_SEND_NAMESP(xip->i_mount, DM_EVENT_NOSPACE, vp,
 822                                 DM_RIGHT_NULL, vp, DM_RIGHT_NULL, NULL, NULL,
 823                                 0, 0, 0); /* Delay flag intentionally  unused */
 824                 if (error)
 825                         goto out_nounlocks;
 826                 if (need_isem)
 827                         down(&inode->i_sem);
 828                 xfs_rwlock(bdp, locktype);
 829                 pos = xip->i_d.di_size;
 830                 ret = 0;
 831                 goto retry;
 832         }
 833
 834         if (*offset > xip->i_d.di_size) {
 835                 xfs_ilock(xip, XFS_ILOCK_EXCL);
 836                 if (*offset > xip->i_d.di_size) {
 837                         xip->i_d.di_size = *offset;
 838                         i_size_write(inode, *offset);
 839                         xip->i_update_core = 1;
 840                         xip->i_update_size = 1;
 841                 }
 842                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
 843         }
 844
 845         error = -ret;
 846         if (ret <= 0)
 847                 goto out_unlock_internal;
 848
 849         XFS_STATS_ADD(xs_write_bytes, ret);
 850
 851         /* Handle various SYNC-type writes */
 852         if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
 853                 /*
 854                  * If we're treating this as O_DSYNC and we have not updated the
 855                  * size, force the log.
 856                  */
 857                 if (!(mp->m_flags & XFS_MOUNT_OSYNCISOSYNC) &&
 858                     !(xip->i_update_size)) {
 859                         xfs_inode_log_item_t    *iip = xip->i_itemp;
 860
 861                         /*
 862                          * If an allocation transaction occurred
 863                          * without extending the size, then we have to force
 864                          * the log up the proper point to ensure that the
 865                          * allocation is permanent.  We can't count on
 866                          * the fact that buffered writes lock out direct I/O
 867                          * writes - the direct I/O write could have extended
 868                          * the size nontransactionally, then finished before
 869                          * we started.  xfs_write_file will think that the file
 870                          * didn't grow but the update isn't safe unless the
 871                          * size change is logged.
 872                          *
 873                          * Force the log if we've committed a transaction
 874                          * against the inode or if someone else has and
 875                          * the commit record hasn't gone to disk (e.g.
 876                          * the inode is pinned).  This guarantees that
 877                          * all changes affecting the inode are permanent
 878                          * when we return.
 879                          */
 880                         if (iip && iip->ili_last_lsn) {
 881                                 xfs_log_force(mp, iip->ili_last_lsn,
 882                                                 XFS_LOG_FORCE | XFS_LOG_SYNC);
 883                         } else if (xfs_ipincount(xip) > 0) {
 884                                 xfs_log_force(mp, (xfs_lsn_t)0,
 885                                                 XFS_LOG_FORCE | XFS_LOG_SYNC);
 886                         }
 887
 888                 } else {
 889                         xfs_trans_t     *tp;
 890
 891                         /*
 892                          * O_SYNC or O_DSYNC _with_ a size update are handled
 893                          * the same way.
 894                          *
 895                          * If the write was synchronous then we need to make
 896                          * sure that the inode modification time is permanent.
 897                          * We'll have updated the timestamp above, so here
 898                          * we use a synchronous transaction to log the inode.
 899                          * It's not fast, but it's necessary.
 900                          *
 901                          * If this a dsync write and the size got changed
 902                          * non-transactionally, then we need to ensure that
 903                          * the size change gets logged in a synchronous
 904                          * transaction.
 905                          */
 906
 907                         tp = xfs_trans_alloc(mp, XFS_TRANS_WRITE_SYNC);
 908                         if ((error = xfs_trans_reserve(tp, 0,
 909                                                       XFS_SWRITE_LOG_RES(mp),
 910                                                       0, 0, 0))) {
 911                                 /* Transaction reserve failed */
 912                                 xfs_trans_cancel(tp, 0);
 913                         } else {
 914                                 /* Transaction reserve successful */
 915                                 xfs_ilock(xip, XFS_ILOCK_EXCL);
 916                                 xfs_trans_ijoin(tp, xip, XFS_ILOCK_EXCL);
 917                                 xfs_trans_ihold(tp, xip);
 918                                 xfs_trans_log_inode(tp, xip, XFS_ILOG_CORE);
 919                                 xfs_trans_set_sync(tp);
 920                                 error = xfs_trans_commit(tp, 0, NULL);
 921                                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
 922                         }
 923                         if (error)
 924                                 goto out_unlock_internal;
 925                 }
 926
 927                 xfs_rwunlock(bdp, locktype);
 928                 if (need_isem)
 929                         up(&inode->i_sem);
 930
 931                 error = sync_page_range(inode, mapping, pos, ret);
 932                 if (!error)
 933                         error = ret;
 934                 return error;
 935         }
 936
 937  out_unlock_internal:
 938         xfs_rwunlock(bdp, locktype);
 939  out_unlock_isem:
 940         if (need_isem)
 941                 up(&inode->i_sem);
 942  out_nounlocks:
 943         return -error;
 944 }
 945
 946 /*
 947  * All xfs metadata buffers except log state machine buffers
 948  * get this attached as their b_bdstrat callback function.
 949  * This is so that we can catch a buffer
 950  * after prematurely unpinning it to forcibly shutdown the filesystem.
 951  */
 952 int
 953 xfs_bdstrat_cb(struct xfs_buf *bp)
 954 {
 955         xfs_mount_t     *mp;
 956
 957         mp = XFS_BUF_FSPRIVATE3(bp, xfs_mount_t *);
 958         if (!XFS_FORCED_SHUTDOWN(mp)) {
 959                 pagebuf_iorequest(bp);
 960                 return 0;
 961         } else {
 962                 xfs_buftrace("XFS__BDSTRAT IOERROR", bp);
 963                 /*
 964                  * Metadata write that didn't get logged but
 965                  * written delayed anyway. These aren't associated
 966                  * with a transaction, and can be ignored.
 967                  */
 968                 if (XFS_BUF_IODONE_FUNC(bp) == NULL &&
 969                     (XFS_BUF_ISREAD(bp)) == 0)
 970                         return (xfs_bioerror_relse(bp));
 971                 else
 972                         return (xfs_bioerror(bp));
 973         }
 974 }
 975
 976
 977 int
 978 xfs_bmap(bhv_desc_t     *bdp,
 979         xfs_off_t       offset,
 980         ssize_t         count,
 981         int             flags,
 982         xfs_iomap_t     *iomapp,
 983         int             *niomaps)
 984 {
 985         xfs_inode_t     *ip = XFS_BHVTOI(bdp);
 986         xfs_iocore_t    *io = &ip->i_iocore;
 987
 988         ASSERT((ip->i_d.di_mode & S_IFMT) == S_IFREG);
 989         ASSERT(((ip->i_d.di_flags & XFS_DIFLAG_REALTIME) != 0) ==
 990                ((ip->i_iocore.io_flags & XFS_IOCORE_RT) != 0));
 991
 992         return xfs_iomap(io, offset, count, flags, iomapp, niomaps);
 993 }
 994
 995 /*
 996  * Wrapper around bdstrat so that we can stop data
 997  * from going to disk in case we are shutting down the filesystem.
 998  * Typically user data goes thru this path; one of the exceptions
 999  * is the superblock.
1000  */
1001 int
1002 xfsbdstrat(
1003         struct xfs_mount        *mp,
1004         struct xfs_buf          *bp)
1005 {
1006         ASSERT(mp);
1007         if (!XFS_FORCED_SHUTDOWN(mp)) {
1008                 /* Grio redirection would go here
1009                  * if (XFS_BUF_IS_GRIO(bp)) {
1010                  */
1011
1012                 pagebuf_iorequest(bp);
1013                 return 0;
1014         }
1015
1016         xfs_buftrace("XFSBDSTRAT IOERROR", bp);
1017         return (xfs_bioerror_relse(bp));
1018 }
1019
1020 /*
1021  * If the underlying (data/log/rt) device is readonly, there are some
1022  * operations that cannot proceed.
1023  */
1024 int
1025 xfs_dev_is_read_only(
1026         xfs_mount_t             *mp,
1027         char                    *message)
1028 {
1029         if (xfs_readonly_buftarg(mp->m_ddev_targp) ||
1030             xfs_readonly_buftarg(mp->m_logdev_targp) ||
1031             (mp->m_rtdev_targp && xfs_readonly_buftarg(mp->m_rtdev_targp))) {
1032                 cmn_err(CE_NOTE,
1033                         "XFS: %s required on read-only device.", message);
1034                 cmn_err(CE_NOTE,
1035                         "XFS: write access unavailable, cannot proceed.");
1036                 return EROFS;
1037         }
1038         return 0;
1039 }