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 *)((unsigned long)current_pid()),
  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 *)((unsigned long)current_pid()),
 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->bt_smask) ||
 237                     (size & target->bt_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         if (unlikely(ioflags & IO_ISDIRECT))
 256                 mutex_lock(&inode->i_mutex);
 257         xfs_ilock(ip, XFS_IOLOCK_SHARED);
 258
 259         if (DM_EVENT_ENABLED(vp->v_vfsp, ip, DM_EVENT_READ) &&
 260             !(ioflags & IO_INVIS)) {
 261                 vrwlock_t locktype = VRWLOCK_READ;
 262                 int dmflags = FILP_DELAY_FLAG(file) | DM_SEM_FLAG_RD(ioflags);
 263
 264                 ret = -XFS_SEND_DATA(mp, DM_EVENT_READ,
 265                                         BHV_TO_VNODE(bdp), *offset, size,
 266                                         dmflags, &locktype);
 267                 if (ret) {
 268                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 269                         goto unlock_mutex;
 270                 }
 271         }
 272
 273         if (unlikely((ioflags & IO_ISDIRECT) && VN_CACHED(vp)))
 274                 VOP_FLUSHINVAL_PAGES(vp, ctooff(offtoct(*offset)),
 275                                                 -1, FI_REMAPF_LOCKED);
 276
 277         xfs_rw_enter_trace(XFS_READ_ENTER, &ip->i_iocore,
 278                                 (void *)iovp, segs, *offset, ioflags);
 279         ret = __generic_file_aio_read(iocb, iovp, segs, offset);
 280         if (ret == -EIOCBQUEUED && !(ioflags & IO_ISAIO))
 281                 ret = wait_on_sync_kiocb(iocb);
 282         if (ret > 0)
 283                 XFS_STATS_ADD(xs_read_bytes, ret);
 284
 285         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 286
 287 unlock_mutex:
 288         if (unlikely(ioflags & IO_ISDIRECT))
 289                 mutex_unlock(&inode->i_mutex);
 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         xfs_inode_t             *ip = XFS_BHVTOI(bdp);
 305         xfs_mount_t             *mp = ip->i_mount;
 306         ssize_t                 ret;
 307
 308         XFS_STATS_INC(xs_read_calls);
 309         if (XFS_FORCED_SHUTDOWN(mp))
 310                 return -EIO;
 311
 312         xfs_ilock(ip, XFS_IOLOCK_SHARED);
 313
 314         if (DM_EVENT_ENABLED(BHV_TO_VNODE(bdp)->v_vfsp, ip, DM_EVENT_READ) &&
 315             (!(ioflags & IO_INVIS))) {
 316                 vrwlock_t locktype = VRWLOCK_READ;
 317                 int error;
 318
 319                 error = XFS_SEND_DATA(mp, DM_EVENT_READ, BHV_TO_VNODE(bdp),
 320                                       *offset, count,
 321                                       FILP_DELAY_FLAG(filp), &locktype);
 322                 if (error) {
 323                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 324                         return -error;
 325                 }
 326         }
 327         xfs_rw_enter_trace(XFS_SENDFILE_ENTER, &ip->i_iocore,
 328                    (void *)(unsigned long)target, count, *offset, ioflags);
 329         ret = generic_file_sendfile(filp, offset, count, actor, target);
 330         if (ret > 0)
 331                 XFS_STATS_ADD(xs_read_bytes, ret);
 332
 333         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 334         return ret;
 335 }
 336
 337 ssize_t
 338 xfs_splice_read(
 339         bhv_desc_t              *bdp,
 340         struct file             *infilp,
 341         struct pipe_inode_info  *pipe,
 342         size_t                  count,
 343         int                     flags,
 344         int                     ioflags,
 345         cred_t                  *credp)
 346 {
 347         xfs_inode_t             *ip = XFS_BHVTOI(bdp);
 348         xfs_mount_t             *mp = ip->i_mount;
 349         ssize_t                 ret;
 350
 351         XFS_STATS_INC(xs_read_calls);
 352         if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 353                 return -EIO;
 354
 355         xfs_ilock(ip, XFS_IOLOCK_SHARED);
 356
 357         if (DM_EVENT_ENABLED(BHV_TO_VNODE(bdp)->v_vfsp, ip, DM_EVENT_READ) &&
 358             (!(ioflags & IO_INVIS))) {
 359                 vrwlock_t locktype = VRWLOCK_READ;
 360                 int error;
 361
 362                 error = XFS_SEND_DATA(mp, DM_EVENT_READ, BHV_TO_VNODE(bdp),
 363                                         infilp->f_pos, count,
 364                                         FILP_DELAY_FLAG(infilp), &locktype);
 365                 if (error) {
 366                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 367                         return -error;
 368                 }
 369         }
 370         xfs_rw_enter_trace(XFS_SPLICE_READ_ENTER, &ip->i_iocore,
 371                            pipe, count, infilp->f_pos, ioflags);
 372         ret = generic_file_splice_read(infilp, pipe, count, flags);
 373         if (ret > 0)
 374                 XFS_STATS_ADD(xs_read_bytes, ret);
 375
 376         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 377         return ret;
 378 }
 379
 380 ssize_t
 381 xfs_splice_write(
 382         bhv_desc_t              *bdp,
 383         struct pipe_inode_info  *pipe,
 384         struct file             *outfilp,
 385         size_t                  count,
 386         int                     flags,
 387         int                     ioflags,
 388         cred_t                  *credp)
 389 {
 390         xfs_inode_t             *ip = XFS_BHVTOI(bdp);
 391         xfs_mount_t             *mp = ip->i_mount;
 392         ssize_t                 ret;
 393
 394         XFS_STATS_INC(xs_write_calls);
 395         if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 396                 return -EIO;
 397
 398         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 399
 400         if (DM_EVENT_ENABLED(BHV_TO_VNODE(bdp)->v_vfsp, ip, DM_EVENT_WRITE) &&
 401             (!(ioflags & IO_INVIS))) {
 402                 vrwlock_t locktype = VRWLOCK_WRITE;
 403                 int error;
 404
 405                 error = XFS_SEND_DATA(mp, DM_EVENT_WRITE, BHV_TO_VNODE(bdp),
 406                                         outfilp->f_pos, count,
 407                                         FILP_DELAY_FLAG(outfilp), &locktype);
 408                 if (error) {
 409                         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 410                         return -error;
 411                 }
 412         }
 413         xfs_rw_enter_trace(XFS_SPLICE_WRITE_ENTER, &ip->i_iocore,
 414                            pipe, count, outfilp->f_pos, ioflags);
 415         ret = generic_file_splice_write(pipe, outfilp, count, flags);
 416         if (ret > 0)
 417                 XFS_STATS_ADD(xs_write_bytes, ret);
 418
 419         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 420         return ret;
 421 }
 422
 423 /*
 424  * This routine is called to handle zeroing any space in the last
 425  * block of the file that is beyond the EOF.  We do this since the
 426  * size is being increased without writing anything to that block
 427  * and we don't want anyone to read the garbage on the disk.
 428  */
 429 STATIC int                              /* error (positive) */
 430 xfs_zero_last_block(
 431         struct inode    *ip,
 432         xfs_iocore_t    *io,
 433         xfs_fsize_t     isize,
 434         xfs_fsize_t     end_size)
 435 {
 436         xfs_fileoff_t   last_fsb;
 437         xfs_mount_t     *mp = io->io_mount;
 438         int             nimaps;
 439         int             zero_offset;
 440         int             zero_len;
 441         int             error = 0;
 442         xfs_bmbt_irec_t imap;
 443         loff_t          loff;
 444
 445         ASSERT(ismrlocked(io->io_lock, MR_UPDATE) != 0);
 446
 447         zero_offset = XFS_B_FSB_OFFSET(mp, isize);
 448         if (zero_offset == 0) {
 449                 /*
 450                  * There are no extra bytes in the last block on disk to
 451                  * zero, so return.
 452                  */
 453                 return 0;
 454         }
 455
 456         last_fsb = XFS_B_TO_FSBT(mp, isize);
 457         nimaps = 1;
 458         error = XFS_BMAPI(mp, NULL, io, last_fsb, 1, 0, NULL, 0, &imap,
 459                           &nimaps, NULL);
 460         if (error) {
 461                 return error;
 462         }
 463         ASSERT(nimaps > 0);
 464         /*
 465          * If the block underlying isize is just a hole, then there
 466          * is nothing to zero.
 467          */
 468         if (imap.br_startblock == HOLESTARTBLOCK) {
 469                 return 0;
 470         }
 471         /*
 472          * Zero the part of the last block beyond the EOF, and write it
 473          * out sync.  We need to drop the ilock while we do this so we
 474          * don't deadlock when the buffer cache calls back to us.
 475          */
 476         XFS_IUNLOCK(mp, io, XFS_ILOCK_EXCL| XFS_EXTSIZE_RD);
 477
 478         loff = XFS_FSB_TO_B(mp, last_fsb);
 479         zero_len = mp->m_sb.sb_blocksize - zero_offset;
 480         error = xfs_iozero(ip, loff + zero_offset, zero_len, end_size);
 481
 482         XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 483         ASSERT(error >= 0);
 484         return error;
 485 }
 486
 487 /*
 488  * Zero any on disk space between the current EOF and the new,
 489  * larger EOF.  This handles the normal case of zeroing the remainder
 490  * of the last block in the file and the unusual case of zeroing blocks
 491  * out beyond the size of the file.  This second case only happens
 492  * with fixed size extents and when the system crashes before the inode
 493  * size was updated but after blocks were allocated.  If fill is set,
 494  * then any holes in the range are filled and zeroed.  If not, the holes
 495  * are left alone as holes.
 496  */
 497
 498 int                                     /* error (positive) */
 499 xfs_zero_eof(
 500         vnode_t         *vp,
 501         xfs_iocore_t    *io,
 502         xfs_off_t       offset,         /* starting I/O offset */
 503         xfs_fsize_t     isize,          /* current inode size */
 504         xfs_fsize_t     end_size)       /* terminal inode size */
 505 {
 506         struct inode    *ip = vn_to_inode(vp);
 507         xfs_fileoff_t   start_zero_fsb;
 508         xfs_fileoff_t   end_zero_fsb;
 509         xfs_fileoff_t   zero_count_fsb;
 510         xfs_fileoff_t   last_fsb;
 511         xfs_extlen_t    buf_len_fsb;
 512         xfs_mount_t     *mp = io->io_mount;
 513         int             nimaps;
 514         int             error = 0;
 515         xfs_bmbt_irec_t imap;
 516
 517         ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
 518         ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));
 519         ASSERT(offset > isize);
 520
 521         /*
 522          * First handle zeroing the block on which isize resides.
 523          * We only zero a part of that block so it is handled specially.
 524          */
 525         error = xfs_zero_last_block(ip, io, isize, end_size);
 526         if (error) {
 527                 ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
 528                 ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));
 529                 return error;
 530         }
 531
 532         /*
 533          * Calculate the range between the new size and the old
 534          * where blocks needing to be zeroed may exist.  To get the
 535          * block where the last byte in the file currently resides,
 536          * we need to subtract one from the size and truncate back
 537          * to a block boundary.  We subtract 1 in case the size is
 538          * exactly on a block boundary.
 539          */
 540         last_fsb = isize ? XFS_B_TO_FSBT(mp, isize - 1) : (xfs_fileoff_t)-1;
 541         start_zero_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)isize);
 542         end_zero_fsb = XFS_B_TO_FSBT(mp, offset - 1);
 543         ASSERT((xfs_sfiloff_t)last_fsb < (xfs_sfiloff_t)start_zero_fsb);
 544         if (last_fsb == end_zero_fsb) {
 545                 /*
 546                  * The size was only incremented on its last block.
 547                  * We took care of that above, so just return.
 548                  */
 549                 return 0;
 550         }
 551
 552         ASSERT(start_zero_fsb <= end_zero_fsb);
 553         while (start_zero_fsb <= end_zero_fsb) {
 554                 nimaps = 1;
 555                 zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
 556                 error = XFS_BMAPI(mp, NULL, io, start_zero_fsb, zero_count_fsb,
 557                                   0, NULL, 0, &imap, &nimaps, NULL);
 558                 if (error) {
 559                         ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
 560                         ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));
 561                         return error;
 562                 }
 563                 ASSERT(nimaps > 0);
 564
 565                 if (imap.br_state == XFS_EXT_UNWRITTEN ||
 566                     imap.br_startblock == HOLESTARTBLOCK) {
 567                         /*
 568                          * This loop handles initializing pages that were
 569                          * partially initialized by the code below this
 570                          * loop. It basically zeroes the part of the page
 571                          * that sits on a hole and sets the page as P_HOLE
 572                          * and calls remapf if it is a mapped file.
 573                          */
 574                         start_zero_fsb = imap.br_startoff + imap.br_blockcount;
 575                         ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 576                         continue;
 577                 }
 578
 579                 /*
 580                  * There are blocks in the range requested.
 581                  * Zero them a single write at a time.  We actually
 582                  * don't zero the entire range returned if it is
 583                  * too big and simply loop around to get the rest.
 584                  * That is not the most efficient thing to do, but it
 585                  * is simple and this path should not be exercised often.
 586                  */
 587                 buf_len_fsb = XFS_FILBLKS_MIN(imap.br_blockcount,
 588                                               mp->m_writeio_blocks << 8);
 589                 /*
 590                  * Drop the inode lock while we're doing the I/O.
 591                  * We'll still have the iolock to protect us.
 592                  */
 593                 XFS_IUNLOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 594
 595                 error = xfs_iozero(ip,
 596                                    XFS_FSB_TO_B(mp, start_zero_fsb),
 597                                    XFS_FSB_TO_B(mp, buf_len_fsb),
 598                                    end_size);
 599
 600                 if (error) {
 601                         goto out_lock;
 602                 }
 603
 604                 start_zero_fsb = imap.br_startoff + buf_len_fsb;
 605                 ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
 606
 607                 XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 608         }
 609
 610         return 0;
 611
 612 out_lock:
 613
 614         XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
 615         ASSERT(error >= 0);
 616         return error;
 617 }
 618
 619 ssize_t                         /* bytes written, or (-) error */
 620 xfs_write(
 621         bhv_desc_t              *bdp,
 622         struct kiocb            *iocb,
 623         const struct iovec      *iovp,
 624         unsigned int            nsegs,
 625         loff_t                  *offset,
 626         int                     ioflags,
 627         cred_t                  *credp)
 628 {
 629         struct file             *file = iocb->ki_filp;
 630         struct address_space    *mapping = file->f_mapping;
 631         struct inode            *inode = mapping->host;
 632         unsigned long           segs = nsegs;
 633         xfs_inode_t             *xip;
 634         xfs_mount_t             *mp;
 635         ssize_t                 ret = 0, error = 0;
 636         xfs_fsize_t             isize, new_size;
 637         xfs_iocore_t            *io;
 638         vnode_t                 *vp;
 639         unsigned long           seg;
 640         int                     iolock;
 641         int                     eventsent = 0;
 642         vrwlock_t               locktype;
 643         size_t                  ocount = 0, count;
 644         loff_t                  pos;
 645         int                     need_i_mutex = 1, need_flush = 0;
 646
 647         XFS_STATS_INC(xs_write_calls);
 648
 649         vp = BHV_TO_VNODE(bdp);
 650         xip = XFS_BHVTOI(bdp);
 651
 652         for (seg = 0; seg < segs; seg++) {
 653                 const struct iovec *iv = &iovp[seg];
 654
 655                 /*
 656                  * If any segment has a negative length, or the cumulative
 657                  * length ever wraps negative then return -EINVAL.
 658                  */
 659                 ocount += iv->iov_len;
 660                 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
 661                         return -EINVAL;
 662                 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
 663                         continue;
 664                 if (seg == 0)
 665                         return -EFAULT;
 666                 segs = seg;
 667                 ocount -= iv->iov_len;  /* This segment is no good */
 668                 break;
 669         }
 670
 671         count = ocount;
 672         pos = *offset;
 673
 674         if (count == 0)
 675                 return 0;
 676
 677         io = &xip->i_iocore;
 678         mp = io->io_mount;
 679
 680         if (XFS_FORCED_SHUTDOWN(mp))
 681                 return -EIO;
 682
 683         fs_check_frozen(vp->v_vfsp, SB_FREEZE_WRITE);
 684
 685         if (ioflags & IO_ISDIRECT) {
 686                 xfs_buftarg_t   *target =
 687                         (xip->i_d.di_flags & XFS_DIFLAG_REALTIME) ?
 688                                 mp->m_rtdev_targp : mp->m_ddev_targp;
 689
 690                 if ((pos & target->bt_smask) || (count & target->bt_smask))
 691                         return XFS_ERROR(-EINVAL);
 692
 693                 if (!VN_CACHED(vp) && pos < i_size_read(inode))
 694                         need_i_mutex = 0;
 695
 696                 if (VN_CACHED(vp))
 697                         need_flush = 1;
 698         }
 699
 700 relock:
 701         if (need_i_mutex) {
 702                 iolock = XFS_IOLOCK_EXCL;
 703                 locktype = VRWLOCK_WRITE;
 704
 705                 mutex_lock(&inode->i_mutex);
 706         } else {
 707                 iolock = XFS_IOLOCK_SHARED;
 708                 locktype = VRWLOCK_WRITE_DIRECT;
 709         }
 710
 711         xfs_ilock(xip, XFS_ILOCK_EXCL|iolock);
 712
 713         isize = i_size_read(inode);
 714
 715         if (file->f_flags & O_APPEND)
 716                 *offset = isize;
 717
 718 start:
 719         error = -generic_write_checks(file, &pos, &count,
 720                                         S_ISBLK(inode->i_mode));
 721         if (error) {
 722                 xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
 723                 goto out_unlock_mutex;
 724         }
 725
 726         new_size = pos + count;
 727         if (new_size > isize)
 728                 io->io_new_size = new_size;
 729
 730         if ((DM_EVENT_ENABLED(vp->v_vfsp, xip, DM_EVENT_WRITE) &&
 731             !(ioflags & IO_INVIS) && !eventsent)) {
 732                 loff_t          savedsize = pos;
 733                 int             dmflags = FILP_DELAY_FLAG(file);
 734
 735                 if (need_i_mutex)
 736                         dmflags |= DM_FLAGS_IMUX;
 737
 738                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
 739                 error = XFS_SEND_DATA(xip->i_mount, DM_EVENT_WRITE, vp,
 740                                       pos, count,
 741                                       dmflags, &locktype);
 742                 if (error) {
 743                         xfs_iunlock(xip, iolock);
 744                         goto out_unlock_mutex;
 745                 }
 746                 xfs_ilock(xip, XFS_ILOCK_EXCL);
 747                 eventsent = 1;
 748
 749                 /*
 750                  * The iolock was dropped and reacquired in XFS_SEND_DATA
 751                  * so we have to recheck the size when appending.
 752                  * We will only "goto start;" once, since having sent the
 753                  * event prevents another call to XFS_SEND_DATA, which is
 754                  * what allows the size to change in the first place.
 755                  */
 756                 if ((file->f_flags & O_APPEND) && savedsize != isize) {
 757                         pos = isize = xip->i_d.di_size;
 758                         goto start;
 759                 }
 760         }
 761
 762         if (likely(!(ioflags & IO_INVIS))) {
 763                 file_update_time(file);
 764                 xfs_ichgtime_fast(xip, inode,
 765                                   XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 766         }
 767
 768         /*
 769          * If the offset is beyond the size of the file, we have a couple
 770          * of things to do. First, if there is already space allocated
 771          * we need to either create holes or zero the disk or ...
 772          *
 773          * If there is a page where the previous size lands, we need
 774          * to zero it out up to the new size.
 775          */
 776
 777         if (pos > isize) {
 778                 error = xfs_zero_eof(BHV_TO_VNODE(bdp), io, pos,
 779                                         isize, pos + count);
 780                 if (error) {
 781                         xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
 782                         goto out_unlock_mutex;
 783                 }
 784         }
 785         xfs_iunlock(xip, XFS_ILOCK_EXCL);
 786
 787         /*
 788          * If we're writing the file then make sure to clear the
 789          * setuid and setgid bits if the process is not being run
 790          * by root.  This keeps people from modifying setuid and
 791          * setgid binaries.
 792          */
 793
 794         if (((xip->i_d.di_mode & S_ISUID) ||
 795             ((xip->i_d.di_mode & (S_ISGID | S_IXGRP)) ==
 796                 (S_ISGID | S_IXGRP))) &&
 797              !capable(CAP_FSETID)) {
 798                 error = xfs_write_clear_setuid(xip);
 799                 if (likely(!error))
 800                         error = -remove_suid(file->f_dentry);
 801                 if (unlikely(error)) {
 802                         xfs_iunlock(xip, iolock);
 803                         goto out_unlock_mutex;
 804                 }
 805         }
 806
 807 retry:
 808         /* We can write back this queue in page reclaim */
 809         current->backing_dev_info = mapping->backing_dev_info;
 810
 811         if ((ioflags & IO_ISDIRECT)) {
 812                 if (need_flush) {
 813                         xfs_inval_cached_trace(io, pos, -1,
 814                                         ctooff(offtoct(pos)), -1);
 815                         VOP_FLUSHINVAL_PAGES(vp, ctooff(offtoct(pos)),
 816                                         -1, FI_REMAPF_LOCKED);
 817                 }
 818
 819                 if (need_i_mutex) {
 820                         /* demote the lock now the cached pages are gone */
 821                         XFS_ILOCK_DEMOTE(mp, io, XFS_IOLOCK_EXCL);
 822                         mutex_unlock(&inode->i_mutex);
 823
 824                         iolock = XFS_IOLOCK_SHARED;
 825                         locktype = VRWLOCK_WRITE_DIRECT;
 826                         need_i_mutex = 0;
 827                 }
 828
 829                 xfs_rw_enter_trace(XFS_DIOWR_ENTER, io, (void *)iovp, segs,
 830                                 *offset, ioflags);
 831                 ret = generic_file_direct_write(iocb, iovp,
 832                                 &segs, pos, offset, count, ocount);
 833
 834                 /*
 835                  * direct-io write to a hole: fall through to buffered I/O
 836                  * for completing the rest of the request.
 837                  */
 838                 if (ret >= 0 && ret != count) {
 839                         XFS_STATS_ADD(xs_write_bytes, ret);
 840
 841                         pos += ret;
 842                         count -= ret;
 843
 844                         need_i_mutex = 1;
 845                         ioflags &= ~IO_ISDIRECT;
 846                         xfs_iunlock(xip, iolock);
 847                         goto relock;
 848                 }
 849         } else {
 850                 xfs_rw_enter_trace(XFS_WRITE_ENTER, io, (void *)iovp, segs,
 851                                 *offset, ioflags);
 852                 ret = generic_file_buffered_write(iocb, iovp, segs,
 853                                 pos, offset, count, ret);
 854         }
 855
 856         current->backing_dev_info = NULL;
 857
 858         if (ret == -EIOCBQUEUED && !(ioflags & IO_ISAIO))
 859                 ret = wait_on_sync_kiocb(iocb);
 860
 861         if ((ret == -ENOSPC) &&
 862             DM_EVENT_ENABLED(vp->v_vfsp, xip, DM_EVENT_NOSPACE) &&
 863             !(ioflags & IO_INVIS)) {
 864
 865                 xfs_rwunlock(bdp, locktype);
 866                 if (need_i_mutex)
 867                         mutex_unlock(&inode->i_mutex);
 868                 error = XFS_SEND_NAMESP(xip->i_mount, DM_EVENT_NOSPACE, vp,
 869                                 DM_RIGHT_NULL, vp, DM_RIGHT_NULL, NULL, NULL,
 870                                 0, 0, 0); /* Delay flag intentionally  unused */
 871                 if (error)
 872                         goto out_nounlocks;
 873                 if (need_i_mutex)
 874                         mutex_lock(&inode->i_mutex);
 875                 xfs_rwlock(bdp, locktype);
 876                 pos = xip->i_d.di_size;
 877                 ret = 0;
 878                 goto retry;
 879         }
 880
 881         isize = i_size_read(inode);
 882         if (unlikely(ret < 0 && ret != -EFAULT && *offset > isize))
 883                 *offset = isize;
 884
 885         if (*offset > xip->i_d.di_size) {
 886                 xfs_ilock(xip, XFS_ILOCK_EXCL);
 887                 if (*offset > xip->i_d.di_size) {
 888                         xip->i_d.di_size = *offset;
 889                         i_size_write(inode, *offset);
 890                         xip->i_update_core = 1;
 891                         xip->i_update_size = 1;
 892                 }
 893                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
 894         }
 895
 896         error = -ret;
 897         if (ret <= 0)
 898                 goto out_unlock_internal;
 899
 900         XFS_STATS_ADD(xs_write_bytes, ret);
 901
 902         /* Handle various SYNC-type writes */
 903         if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
 904                 /*
 905                  * If we're treating this as O_DSYNC and we have not updated the
 906                  * size, force the log.
 907                  */
 908                 if (!(mp->m_flags & XFS_MOUNT_OSYNCISOSYNC) &&
 909                     !(xip->i_update_size)) {
 910                         xfs_inode_log_item_t    *iip = xip->i_itemp;
 911
 912                         /*
 913                          * If an allocation transaction occurred
 914                          * without extending the size, then we have to force
 915                          * the log up the proper point to ensure that the
 916                          * allocation is permanent.  We can't count on
 917                          * the fact that buffered writes lock out direct I/O
 918                          * writes - the direct I/O write could have extended
 919                          * the size nontransactionally, then finished before
 920                          * we started.  xfs_write_file will think that the file
 921                          * didn't grow but the update isn't safe unless the
 922                          * size change is logged.
 923                          *
 924                          * Force the log if we've committed a transaction
 925                          * against the inode or if someone else has and
 926                          * the commit record hasn't gone to disk (e.g.
 927                          * the inode is pinned).  This guarantees that
 928                          * all changes affecting the inode are permanent
 929                          * when we return.
 930                          */
 931                         if (iip && iip->ili_last_lsn) {
 932                                 xfs_log_force(mp, iip->ili_last_lsn,
 933                                                 XFS_LOG_FORCE | XFS_LOG_SYNC);
 934                         } else if (xfs_ipincount(xip) > 0) {
 935                                 xfs_log_force(mp, (xfs_lsn_t)0,
 936                                                 XFS_LOG_FORCE | XFS_LOG_SYNC);
 937                         }
 938
 939                 } else {
 940                         xfs_trans_t     *tp;
 941
 942                         /*
 943                          * O_SYNC or O_DSYNC _with_ a size update are handled
 944                          * the same way.
 945                          *
 946                          * If the write was synchronous then we need to make
 947                          * sure that the inode modification time is permanent.
 948                          * We'll have updated the timestamp above, so here
 949                          * we use a synchronous transaction to log the inode.
 950                          * It's not fast, but it's necessary.
 951                          *
 952                          * If this a dsync write and the size got changed
 953                          * non-transactionally, then we need to ensure that
 954                          * the size change gets logged in a synchronous
 955                          * transaction.
 956                          */
 957
 958                         tp = xfs_trans_alloc(mp, XFS_TRANS_WRITE_SYNC);
 959                         if ((error = xfs_trans_reserve(tp, 0,
 960                                                       XFS_SWRITE_LOG_RES(mp),
 961                                                       0, 0, 0))) {
 962                                 /* Transaction reserve failed */
 963                                 xfs_trans_cancel(tp, 0);
 964                         } else {
 965                                 /* Transaction reserve successful */
 966                                 xfs_ilock(xip, XFS_ILOCK_EXCL);
 967                                 xfs_trans_ijoin(tp, xip, XFS_ILOCK_EXCL);
 968                                 xfs_trans_ihold(tp, xip);
 969                                 xfs_trans_log_inode(tp, xip, XFS_ILOG_CORE);
 970                                 xfs_trans_set_sync(tp);
 971                                 error = xfs_trans_commit(tp, 0, NULL);
 972                                 xfs_iunlock(xip, XFS_ILOCK_EXCL);
 973                         }
 974                         if (error)
 975                                 goto out_unlock_internal;
 976                 }
 977
 978                 xfs_rwunlock(bdp, locktype);
 979                 if (need_i_mutex)
 980                         mutex_unlock(&inode->i_mutex);
 981
 982                 error = sync_page_range(inode, mapping, pos, ret);
 983                 if (!error)
 984                         error = ret;
 985                 return error;
 986         }
 987
 988  out_unlock_internal:
 989         xfs_rwunlock(bdp, locktype);
 990  out_unlock_mutex:
 991         if (need_i_mutex)
 992                 mutex_unlock(&inode->i_mutex);
 993  out_nounlocks:
 994         return -error;
 995 }
 996
 997 /*
 998  * All xfs metadata buffers except log state machine buffers
 999  * get this attached as their b_bdstrat callback function.
1000  * This is so that we can catch a buffer
1001  * after prematurely unpinning it to forcibly shutdown the filesystem.
1002  */
1003 int
1004 xfs_bdstrat_cb(struct xfs_buf *bp)
1005 {
1006         xfs_mount_t     *mp;
1007
1008         mp = XFS_BUF_FSPRIVATE3(bp, xfs_mount_t *);
1009         if (!XFS_FORCED_SHUTDOWN(mp)) {
1010                 xfs_buf_iorequest(bp);
1011                 return 0;
1012         } else {
1013                 xfs_buftrace("XFS__BDSTRAT IOERROR", bp);
1014                 /*
1015                  * Metadata write that didn't get logged but
1016                  * written delayed anyway. These aren't associated
1017                  * with a transaction, and can be ignored.
1018                  */
1019                 if (XFS_BUF_IODONE_FUNC(bp) == NULL &&
1020                     (XFS_BUF_ISREAD(bp)) == 0)
1021                         return (xfs_bioerror_relse(bp));
1022                 else
1023                         return (xfs_bioerror(bp));
1024         }
1025 }
1026
1027
1028 int
1029 xfs_bmap(bhv_desc_t     *bdp,
1030         xfs_off_t       offset,
1031         ssize_t         count,
1032         int             flags,
1033         xfs_iomap_t     *iomapp,
1034         int             *niomaps)
1035 {
1036         xfs_inode_t     *ip = XFS_BHVTOI(bdp);
1037         xfs_iocore_t    *io = &ip->i_iocore;
1038
1039         ASSERT((ip->i_d.di_mode & S_IFMT) == S_IFREG);
1040         ASSERT(((ip->i_d.di_flags & XFS_DIFLAG_REALTIME) != 0) ==
1041                ((ip->i_iocore.io_flags & XFS_IOCORE_RT) != 0));
1042
1043         return xfs_iomap(io, offset, count, flags, iomapp, niomaps);
1044 }
1045
1046 /*
1047  * Wrapper around bdstrat so that we can stop data
1048  * from going to disk in case we are shutting down the filesystem.
1049  * Typically user data goes thru this path; one of the exceptions
1050  * is the superblock.
1051  */
1052 int
1053 xfsbdstrat(
1054         struct xfs_mount        *mp,
1055         struct xfs_buf          *bp)
1056 {
1057         ASSERT(mp);
1058         if (!XFS_FORCED_SHUTDOWN(mp)) {
1059                 /* Grio redirection would go here
1060                  * if (XFS_BUF_IS_GRIO(bp)) {
1061                  */
1062
1063                 xfs_buf_iorequest(bp);
1064                 return 0;
1065         }
1066
1067         xfs_buftrace("XFSBDSTRAT IOERROR", bp);
1068         return (xfs_bioerror_relse(bp));
1069 }
1070
1071 /*
1072  * If the underlying (data/log/rt) device is readonly, there are some
1073  * operations that cannot proceed.
1074  */
1075 int
1076 xfs_dev_is_read_only(
1077         xfs_mount_t             *mp,
1078         char                    *message)
1079 {
1080         if (xfs_readonly_buftarg(mp->m_ddev_targp) ||
1081             xfs_readonly_buftarg(mp->m_logdev_targp) ||
1082             (mp->m_rtdev_targp && xfs_readonly_buftarg(mp->m_rtdev_targp))) {
1083                 cmn_err(CE_NOTE,
1084                         "XFS: %s required on read-only device.", message);
1085                 cmn_err(CE_NOTE,
1086                         "XFS: write access unavailable, cannot proceed.");
1087                 return EROFS;
1088         }
1089         return 0;
1090 }