sys/ufs/lfs/ulfs_readwrite.c

   1 /*      $NetBSD: ulfs_readwrite.c,v 1.19 2015/07/24 06:59:32 dholland Exp $     */
   2 /*  from NetBSD: ufs_readwrite.c,v 1.105 2013/01/22 09:39:18 dholland Exp  */
   3
   4 /*-
   5  * Copyright (c) 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  *      @(#)ufs_readwrite.c     8.11 (Berkeley) 5/8/95
  33  */
  34
  35 #include <sys/cdefs.h>
  36 __KERNEL_RCSID(1, "$NetBSD: ulfs_readwrite.c,v 1.19 2015/07/24 06:59:32 dholland Exp $");
  37
  38 #ifdef LFS_READWRITE
  39 #define FS                      struct lfs
  40 #define I_FS                    i_lfs
  41 #define READ                    lfs_read
  42 #define READ_S                  "lfs_read"
  43 #define WRITE                   lfs_write
  44 #define WRITE_S                 "lfs_write"
  45 #define BUFRD                   lfs_bufrd
  46 #define BUFWR                   lfs_bufwr
  47 #define fs_sb_getbsize(fs)      lfs_sb_getbsize(fs)
  48 #define fs_bmask                lfs_bmask
  49 #else
  50 #define FS                      struct fs
  51 #define I_FS                    i_fs
  52 #define READ                    ffs_read
  53 #define READ_S                  "ffs_read"
  54 #define WRITE                   ffs_write
  55 #define WRITE_S                 "ffs_write"
  56 #define BUFRD                   ffs_bufrd
  57 #define BUFWR                   ffs_bufwr
  58 #define fs_sb_getbsize(fs)      (fs)->fs_bsize
  59 #endif
  60
  61 static int      ulfs_post_read_update(struct vnode *, int, int);
  62 static int      ulfs_post_write_update(struct vnode *, struct uio *, int,
  63                     kauth_cred_t, off_t, int, int, int);
  64
  65 /*
  66  * Vnode op for reading.
  67  */
  68 /* ARGSUSED */
  69 int
  70 READ(void *v)
  71 {
  72         struct vop_read_args /* {
  73                 struct vnode *a_vp;
  74                 struct uio *a_uio;
  75                 int a_ioflag;
  76                 kauth_cred_t a_cred;
  77         } */ *ap = v;
  78         struct vnode *vp;
  79         struct inode *ip;
  80         struct uio *uio;
  81         FS *fs;
  82         vsize_t bytelen;
  83         int error, ioflag, advice;
  84
  85         vp = ap->a_vp;
  86         ip = VTOI(vp);
  87         fs = ip->I_FS;
  88         uio = ap->a_uio;
  89         ioflag = ap->a_ioflag;
  90         error = 0;
  91
  92         KASSERT(uio->uio_rw == UIO_READ);
  93         KASSERT(vp->v_type == VREG || vp->v_type == VDIR);
  94
  95         /* XXX Eliminate me by refusing directory reads from userland.  */
  96         if (vp->v_type == VDIR)
  97                 return BUFRD(vp, uio, ioflag, ap->a_cred);
  98 #ifdef LFS_READWRITE
  99         /* XXX Eliminate me by using ufs_bufio in lfs.  */
 100         if (vp->v_type == VREG && ip->i_number == LFS_IFILE_INUM)
 101                 return BUFRD(vp, uio, ioflag, ap->a_cred);
 102 #endif
 103         if ((u_int64_t)uio->uio_offset > fs->um_maxfilesize)
 104                 return (EFBIG);
 105         if (uio->uio_resid == 0)
 106                 return (0);
 107
 108 #ifndef LFS_READWRITE
 109         if ((ip->i_flags & (SF_SNAPSHOT | SF_SNAPINVAL)) == SF_SNAPSHOT)
 110                 return ffs_snapshot_read(vp, uio, ioflag);
 111 #endif /* !LFS_READWRITE */
 112
 113         fstrans_start(vp->v_mount, FSTRANS_SHARED);
 114
 115         if (uio->uio_offset >= ip->i_size)
 116                 goto out;
 117
 118         KASSERT(vp->v_type == VREG);
 119         advice = IO_ADV_DECODE(ap->a_ioflag);
 120         while (uio->uio_resid > 0) {
 121                 if (ioflag & IO_DIRECT) {
 122                         genfs_directio(vp, uio, ioflag);
 123                 }
 124                 bytelen = MIN(ip->i_size - uio->uio_offset, uio->uio_resid);
 125                 if (bytelen == 0)
 126                         break;
 127                 error = ubc_uiomove(&vp->v_uobj, uio, bytelen, advice,
 128                     UBC_READ | UBC_PARTIALOK | UBC_UNMAP_FLAG(vp));
 129                 if (error)
 130                         break;
 131         }
 132
 133  out:
 134         error = ulfs_post_read_update(vp, ap->a_ioflag, error);
 135         fstrans_done(vp->v_mount);
 136         return (error);
 137 }
 138
 139 /*
 140  * UFS op for reading via the buffer cache
 141  */
 142 int
 143 BUFRD(struct vnode *vp, struct uio *uio, int ioflag, kauth_cred_t cred)
 144 {
 145         struct inode *ip;
 146         FS *fs;
 147         struct buf *bp;
 148         daddr_t lbn, nextlbn;
 149         off_t bytesinfile;
 150         long size, xfersize, blkoffset;
 151         int error;
 152
 153         KASSERT(VOP_ISLOCKED(vp));
 154         KASSERT(vp->v_type == VDIR || vp->v_type == VLNK ||
 155             vp->v_type == VREG);
 156         KASSERT(uio->uio_rw == UIO_READ);
 157
 158         ip = VTOI(vp);
 159         fs = ip->I_FS;
 160         error = 0;
 161
 162         KASSERT(vp->v_type != VLNK || ip->i_size < fs->um_maxsymlinklen);
 163         KASSERT(vp->v_type != VLNK || fs->um_maxsymlinklen != 0 ||
 164             DIP(ip, blocks) == 0);
 165         KASSERT(vp->v_type != VREG || vp == fs->lfs_ivnode);
 166         KASSERT(vp->v_type != VREG || ip->i_number == LFS_IFILE_INUM);
 167
 168         if (uio->uio_offset > fs->um_maxfilesize)
 169                 return EFBIG;
 170         if (uio->uio_resid == 0)
 171                 return 0;
 172
 173 #ifndef LFS_READWRITE
 174         KASSERT(!ISSET(ip->i_flags, (SF_SNAPSHOT | SF_SNAPINVAL)));
 175 #endif
 176
 177         fstrans_start(vp->v_mount, FSTRANS_SHARED);
 178
 179         if (uio->uio_offset >= ip->i_size)
 180                 goto out;
 181
 182         for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
 183                 bytesinfile = ip->i_size - uio->uio_offset;
 184                 if (bytesinfile <= 0)
 185                         break;
 186                 lbn = lfs_lblkno(fs, uio->uio_offset);
 187                 nextlbn = lbn + 1;
 188                 size = lfs_blksize(fs, ip, lbn);
 189                 blkoffset = lfs_blkoff(fs, uio->uio_offset);
 190                 xfersize = MIN(MIN(fs_sb_getbsize(fs) - blkoffset, uio->uio_resid),
 191                     bytesinfile);
 192
 193                 if (lfs_lblktosize(fs, nextlbn) >= ip->i_size)
 194                         error = bread(vp, lbn, size, 0, &bp);
 195                 else {
 196                         int nextsize = lfs_blksize(fs, ip, nextlbn);
 197                         error = breadn(vp, lbn,
 198                             size, &nextlbn, &nextsize, 1, 0, &bp);
 199                 }
 200                 if (error)
 201                         break;
 202
 203                 /*
 204                  * We should only get non-zero b_resid when an I/O error
 205                  * has occurred, which should cause us to break above.
 206                  * However, if the short read did not cause an error,
 207                  * then we want to ensure that we do not uiomove bad
 208                  * or uninitialized data.
 209                  */
 210                 size -= bp->b_resid;
 211                 if (size < xfersize) {
 212                         if (size == 0)
 213                                 break;
 214                         xfersize = size;
 215                 }
 216                 error = uiomove((char *)bp->b_data + blkoffset, xfersize, uio);
 217                 if (error)
 218                         break;
 219                 brelse(bp, 0);
 220         }
 221         if (bp != NULL)
 222                 brelse(bp, 0);
 223
 224  out:
 225         error = ulfs_post_read_update(vp, ioflag, error);
 226         fstrans_done(vp->v_mount);
 227         return (error);
 228 }
 229
 230 static int
 231 ulfs_post_read_update(struct vnode *vp, int ioflag, int oerror)
 232 {
 233         struct inode *ip = VTOI(vp);
 234         int error = oerror;
 235
 236         if (!(vp->v_mount->mnt_flag & MNT_NOATIME)) {
 237                 ip->i_flag |= IN_ACCESS;
 238                 if ((ioflag & IO_SYNC) == IO_SYNC) {
 239                         error = lfs_update(vp, NULL, NULL, UPDATE_WAIT);
 240                 }
 241         }
 242
 243         /* Read error overrides any inode update error.  */
 244         if (oerror)
 245                 error = oerror;
 246         return error;
 247 }
 248
 249 /*
 250  * Vnode op for writing.
 251  */
 252 int
 253 WRITE(void *v)
 254 {
 255         struct vop_write_args /* {
 256                 struct vnode *a_vp;
 257                 struct uio *a_uio;
 258                 int a_ioflag;
 259                 kauth_cred_t a_cred;
 260         } */ *ap = v;
 261         struct vnode *vp;
 262         struct uio *uio;
 263         struct inode *ip;
 264         FS *fs;
 265         kauth_cred_t cred;
 266         off_t osize, origoff, oldoff, preallocoff, endallocoff, nsize;
 267         int blkoffset, error, flags, ioflag, resid;
 268         int aflag;
 269         int extended=0;
 270         vsize_t bytelen;
 271         bool async;
 272
 273         cred = ap->a_cred;
 274         ioflag = ap->a_ioflag;
 275         uio = ap->a_uio;
 276         vp = ap->a_vp;
 277         ip = VTOI(vp);
 278
 279         KASSERT(vp->v_size == ip->i_size);
 280         KASSERT(uio->uio_rw == UIO_WRITE);
 281         KASSERT(vp->v_type == VREG);
 282
 283         if (ioflag & IO_APPEND)
 284                 uio->uio_offset = ip->i_size;
 285         if ((ip->i_flags & APPEND) && uio->uio_offset != ip->i_size)
 286                 return (EPERM);
 287
 288         fs = ip->I_FS;
 289         if (uio->uio_offset < 0 ||
 290             (u_int64_t)uio->uio_offset + uio->uio_resid > fs->um_maxfilesize)
 291                 return (EFBIG);
 292 #ifdef LFS_READWRITE
 293         /* Disallow writes to the Ifile, even if noschg flag is removed */
 294         /* XXX can this go away when the Ifile is no longer in the namespace? */
 295         if (vp == fs->lfs_ivnode)
 296                 return (EPERM);
 297 #endif
 298         if (uio->uio_resid == 0)
 299                 return (0);
 300
 301         fstrans_start(vp->v_mount, FSTRANS_SHARED);
 302
 303         flags = ioflag & IO_SYNC ? B_SYNC : 0;
 304         async = vp->v_mount->mnt_flag & MNT_ASYNC;
 305         origoff = uio->uio_offset;
 306         resid = uio->uio_resid;
 307         osize = ip->i_size;
 308         error = 0;
 309
 310         KASSERT(vp->v_type == VREG);
 311
 312 #ifdef LFS_READWRITE
 313         async = true;
 314         lfs_availwait(fs, lfs_btofsb(fs, uio->uio_resid));
 315         lfs_check(vp, LFS_UNUSED_LBN, 0);
 316 #endif /* !LFS_READWRITE */
 317
 318         preallocoff = round_page(lfs_blkroundup(fs, MAX(osize, uio->uio_offset)));
 319         aflag = ioflag & IO_SYNC ? B_SYNC : 0;
 320         nsize = MAX(osize, uio->uio_offset + uio->uio_resid);
 321         endallocoff = nsize - lfs_blkoff(fs, nsize);
 322
 323         /*
 324          * if we're increasing the file size, deal with expanding
 325          * the fragment if there is one.
 326          */
 327
 328         if (nsize > osize && lfs_lblkno(fs, osize) < ULFS_NDADDR &&
 329             lfs_lblkno(fs, osize) != lfs_lblkno(fs, nsize) &&
 330             lfs_blkroundup(fs, osize) != osize) {
 331                 off_t eob;
 332
 333                 eob = lfs_blkroundup(fs, osize);
 334                 uvm_vnp_setwritesize(vp, eob);
 335                 error = ulfs_balloc_range(vp, osize, eob - osize, cred, aflag);
 336                 if (error)
 337                         goto out;
 338                 if (flags & B_SYNC) {
 339                         mutex_enter(vp->v_interlock);
 340                         VOP_PUTPAGES(vp, trunc_page(osize & lfs_sb_getbmask(fs)),
 341                             round_page(eob),
 342                             PGO_CLEANIT | PGO_SYNCIO);
 343                 }
 344         }
 345
 346         while (uio->uio_resid > 0) {
 347                 int ubc_flags = UBC_WRITE;
 348                 bool overwrite; /* if we're overwrite a whole block */
 349                 off_t newoff;
 350
 351                 if (ioflag & IO_DIRECT) {
 352                         genfs_directio(vp, uio, ioflag);
 353                 }
 354
 355                 oldoff = uio->uio_offset;
 356                 blkoffset = lfs_blkoff(fs, uio->uio_offset);
 357                 bytelen = MIN(fs_sb_getbsize(fs) - blkoffset, uio->uio_resid);
 358                 if (bytelen == 0) {
 359                         break;
 360                 }
 361
 362                 /*
 363                  * if we're filling in a hole, allocate the blocks now and
 364                  * initialize the pages first.  if we're extending the file,
 365                  * we can safely allocate blocks without initializing pages
 366                  * since the new blocks will be inaccessible until the write
 367                  * is complete.
 368                  */
 369                 overwrite = uio->uio_offset >= preallocoff &&
 370                     uio->uio_offset < endallocoff;
 371                 if (!overwrite && (vp->v_vflag & VV_MAPPED) == 0 &&
 372                     lfs_blkoff(fs, uio->uio_offset) == 0 &&
 373                     (uio->uio_offset & PAGE_MASK) == 0) {
 374                         vsize_t len;
 375
 376                         len = trunc_page(bytelen);
 377                         len -= lfs_blkoff(fs, len);
 378                         if (len > 0) {
 379                                 overwrite = true;
 380                                 bytelen = len;
 381                         }
 382                 }
 383
 384                 newoff = oldoff + bytelen;
 385                 if (vp->v_size < newoff) {
 386                         uvm_vnp_setwritesize(vp, newoff);
 387                 }
 388
 389                 if (!overwrite) {
 390                         error = ulfs_balloc_range(vp, uio->uio_offset, bytelen,
 391                             cred, aflag);
 392                         if (error)
 393                                 break;
 394                 } else {
 395                         genfs_node_wrlock(vp);
 396                         error = GOP_ALLOC(vp, uio->uio_offset, bytelen,
 397                             aflag, cred);
 398                         genfs_node_unlock(vp);
 399                         if (error)
 400                                 break;
 401                         ubc_flags |= UBC_FAULTBUSY;
 402                 }
 403
 404                 /*
 405                  * copy the data.
 406                  */
 407
 408                 error = ubc_uiomove(&vp->v_uobj, uio, bytelen,
 409                     IO_ADV_DECODE(ioflag), ubc_flags | UBC_UNMAP_FLAG(vp));
 410
 411                 /*
 412                  * update UVM's notion of the size now that we've
 413                  * copied the data into the vnode's pages.
 414                  *
 415                  * we should update the size even when uiomove failed.
 416                  */
 417
 418                 if (vp->v_size < newoff) {
 419                         uvm_vnp_setsize(vp, newoff);
 420                         extended = 1;
 421                 }
 422
 423                 if (error)
 424                         break;
 425
 426                 /*
 427                  * flush what we just wrote if necessary.
 428                  * XXXUBC simplistic async flushing.
 429                  */
 430
 431 #ifndef LFS_READWRITE
 432                 if (!async && oldoff >> 16 != uio->uio_offset >> 16) {
 433                         mutex_enter(vp->v_interlock);
 434                         error = VOP_PUTPAGES(vp, (oldoff >> 16) << 16,
 435                             (uio->uio_offset >> 16) << 16,
 436                             PGO_CLEANIT | PGO_LAZY);
 437                         if (error)
 438                                 break;
 439                 }
 440 #else
 441                 __USE(async);
 442 #endif
 443         }
 444         if (error == 0 && ioflag & IO_SYNC) {
 445                 mutex_enter(vp->v_interlock);
 446                 error = VOP_PUTPAGES(vp, trunc_page(origoff & lfs_sb_getbmask(fs)),
 447                     round_page(lfs_blkroundup(fs, uio->uio_offset)),
 448                     PGO_CLEANIT | PGO_SYNCIO);
 449         }
 450
 451 out:
 452         error = ulfs_post_write_update(vp, uio, ioflag, cred, osize, resid,
 453             extended, error);
 454         fstrans_done(vp->v_mount);
 455
 456         return (error);
 457 }
 458
 459 /*
 460  * UFS op for writing via the buffer cache
 461  */
 462 int
 463 BUFWR(struct vnode *vp, struct uio *uio, int ioflag, kauth_cred_t cred)
 464 {
 465         struct inode *ip;
 466         FS *fs;
 467         int flags;
 468         struct buf *bp;
 469         off_t osize;
 470         int resid, xfersize, size, blkoffset;
 471         daddr_t lbn;
 472         int extended=0;
 473         int error;
 474 #ifdef LFS_READWRITE
 475         bool need_unreserve = false;
 476 #endif
 477
 478         KASSERT(ISSET(ioflag, IO_NODELOCKED));
 479         KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);
 480         KASSERT(vp->v_type == VDIR || vp->v_type == VLNK);
 481         KASSERT(vp->v_type != VDIR || ISSET(ioflag, IO_SYNC));
 482         KASSERT(uio->uio_rw == UIO_WRITE);
 483
 484         ip = VTOI(vp);
 485         fs = ip->I_FS;
 486
 487         KASSERT(vp->v_size == ip->i_size);
 488
 489         if (uio->uio_offset < 0 ||
 490             uio->uio_resid > fs->um_maxfilesize ||
 491             uio->uio_offset > (fs->um_maxfilesize - uio->uio_resid))
 492                 return EFBIG;
 493 #ifdef LFS_READWRITE
 494         KASSERT(vp != fs->lfs_ivnode);
 495 #endif
 496         if (uio->uio_resid == 0)
 497                 return 0;
 498
 499         fstrans_start(vp->v_mount, FSTRANS_SHARED);
 500
 501         flags = ioflag & IO_SYNC ? B_SYNC : 0;
 502         resid = uio->uio_resid;
 503         osize = ip->i_size;
 504         error = 0;
 505
 506         KASSERT(vp->v_type != VREG);
 507
 508 #ifdef LFS_READWRITE
 509         lfs_availwait(fs, lfs_btofsb(fs, uio->uio_resid));
 510         lfs_check(vp, LFS_UNUSED_LBN, 0);
 511 #endif /* !LFS_READWRITE */
 512
 513         /* XXX Should never have pages cached here.  */
 514         KASSERT(vp->v_uobj.uo_npages == 0);
 515         while (uio->uio_resid > 0) {
 516                 lbn = lfs_lblkno(fs, uio->uio_offset);
 517                 blkoffset = lfs_blkoff(fs, uio->uio_offset);
 518                 xfersize = MIN(fs_sb_getbsize(fs) - blkoffset, uio->uio_resid);
 519                 if (fs_sb_getbsize(fs) > xfersize)
 520                         flags |= B_CLRBUF;
 521                 else
 522                         flags &= ~B_CLRBUF;
 523
 524 #ifdef LFS_READWRITE
 525                 error = lfs_reserve(fs, vp, NULL,
 526                     lfs_btofsb(fs, (ULFS_NIADDR + 1) << lfs_sb_getbshift(fs)));
 527                 if (error)
 528                         break;
 529                 need_unreserve = true;
 530 #endif
 531                 error = lfs_balloc(vp, uio->uio_offset, xfersize, cred, flags,
 532                     &bp);
 533
 534                 if (error)
 535                         break;
 536                 if (uio->uio_offset + xfersize > ip->i_size) {
 537                         ip->i_size = uio->uio_offset + xfersize;
 538                         DIP_ASSIGN(ip, size, ip->i_size);
 539                         uvm_vnp_setsize(vp, ip->i_size);
 540                         extended = 1;
 541                 }
 542                 size = lfs_blksize(fs, ip, lbn) - bp->b_resid;
 543                 if (xfersize > size)
 544                         xfersize = size;
 545
 546                 error = uiomove((char *)bp->b_data + blkoffset, xfersize, uio);
 547
 548                 /*
 549                  * if we didn't clear the block and the uiomove failed,
 550                  * the buf will now contain part of some other file,
 551                  * so we need to invalidate it.
 552                  */
 553                 if (error && (flags & B_CLRBUF) == 0) {
 554                         brelse(bp, BC_INVAL);
 555                         break;
 556                 }
 557 #ifdef LFS_READWRITE
 558                 (void)VOP_BWRITE(bp->b_vp, bp);
 559                 lfs_reserve(fs, vp, NULL,
 560                     -lfs_btofsb(fs, (ULFS_NIADDR + 1) << lfs_sb_getbshift(fs)));
 561                 need_unreserve = false;
 562 #else
 563                 if (ioflag & IO_SYNC)
 564                         (void)bwrite(bp);
 565                 else if (xfersize + blkoffset == fs->fs_bsize)
 566                         bawrite(bp);
 567                 else
 568                         bdwrite(bp);
 569 #endif
 570                 if (error || xfersize == 0)
 571                         break;
 572         }
 573 #ifdef LFS_READWRITE
 574         if (need_unreserve) {
 575                 lfs_reserve(fs, vp, NULL,
 576                     -lfs_btofsb(fs, (ULFS_NIADDR + 1) << lfs_sb_getbshift(fs)));
 577         }
 578 #endif
 579
 580         error = ulfs_post_write_update(vp, uio, ioflag, cred, osize, resid,
 581             extended, error);
 582         fstrans_done(vp->v_mount);
 583
 584         return (error);
 585 }
 586
 587 static int
 588 ulfs_post_write_update(struct vnode *vp, struct uio *uio, int ioflag,
 589     kauth_cred_t cred, off_t osize, int resid, int extended, int oerror)
 590 {
 591         struct inode *ip = VTOI(vp);
 592         int error = oerror;
 593
 594         /* Trigger ctime and mtime updates, and atime if MNT_RELATIME.  */
 595         ip->i_flag |= IN_CHANGE | IN_UPDATE;
 596         if (vp->v_mount->mnt_flag & MNT_RELATIME)
 597                 ip->i_flag |= IN_ACCESS;
 598
 599         /*
 600          * If we successfully wrote any data and we are not the superuser,
 601          * we clear the setuid and setgid bits as a precaution against
 602          * tampering.
 603          */
 604         if (resid > uio->uio_resid && cred) {
 605                 if (ip->i_mode & ISUID) {
 606                         if (kauth_authorize_vnode(cred,
 607                             KAUTH_VNODE_RETAIN_SUID, vp, NULL, EPERM) != 0) {
 608                                 ip->i_mode &= ~ISUID;
 609                                 DIP_ASSIGN(ip, mode, ip->i_mode);
 610                         }
 611                 }
 612
 613                 if (ip->i_mode & ISGID) {
 614                         if (kauth_authorize_vnode(cred,
 615                             KAUTH_VNODE_RETAIN_SGID, vp, NULL, EPERM) != 0) {
 616                                 ip->i_mode &= ~ISGID;
 617                                 DIP_ASSIGN(ip, mode, ip->i_mode);
 618                         }
 619                 }
 620         }
 621
 622         /* If we successfully wrote anything, notify kevent listeners.  */
 623         if (resid > uio->uio_resid)
 624                 VN_KNOTE(vp, NOTE_WRITE | (extended ? NOTE_EXTEND : 0));
 625
 626         /*
 627          * Update the size on disk: truncate back to original size on
 628          * error, or reflect the new size on success.
 629          */
 630         if (error) {
 631                 (void) lfs_truncate(vp, osize, ioflag & IO_SYNC, cred);
 632                 uio->uio_offset -= resid - uio->uio_resid;
 633                 uio->uio_resid = resid;
 634         } else if (resid > uio->uio_resid && (ioflag & IO_SYNC) == IO_SYNC) {
 635                 error = lfs_update(vp, NULL, NULL, UPDATE_WAIT);
 636         } else {
 637                 /* nothing */
 638         }
 639
 640         /* Make sure the vnode uvm size matches the inode file size.  */
 641         KASSERT(vp->v_size == ip->i_size);
 642
 643         /* Write error overrides any inode update error.  */
 644         if (oerror)
 645                 error = oerror;
 646         return error;
 647 }