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ulfs_readwrite.c revision 1.12
      1 /*	$NetBSD: ulfs_readwrite.c,v 1.12 2015/03/28 17:08:53 riastradh 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 1.12 2015/03/28 17:08:53 riastradh 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_bsize		lfs_bsize
     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 #endif
     59 
     60 static int	ulfs_post_read_update(struct vnode *, int, int);
     61 static int	ulfs_post_write_update(struct vnode *, struct uio *, int,
     62 		    kauth_cred_t, off_t, int, int, int);
     63 
     64 /*
     65  * Vnode op for reading.
     66  */
     67 /* ARGSUSED */
     68 int
     69 READ(void *v)
     70 {
     71 	struct vop_read_args /* {
     72 		struct vnode *a_vp;
     73 		struct uio *a_uio;
     74 		int a_ioflag;
     75 		kauth_cred_t a_cred;
     76 	} */ *ap = v;
     77 	struct vnode *vp;
     78 	struct inode *ip;
     79 	struct uio *uio;
     80 	FS *fs;
     81 	vsize_t bytelen;
     82 	int error, ioflag, advice;
     83 
     84 	vp = ap->a_vp;
     85 	ip = VTOI(vp);
     86 	fs = ip->I_FS;
     87 	uio = ap->a_uio;
     88 	ioflag = ap->a_ioflag;
     89 	error = 0;
     90 
     91 	KASSERT(uio->uio_rw == UIO_READ);
     92 	KASSERT(vp->v_type == VREG || vp->v_type == VDIR);
     93 
     94 	/* XXX Eliminate me by refusing directory reads from userland.  */
     95 	if (vp->v_type == VDIR)
     96 		return BUFRD(vp, uio, ioflag, ap->a_cred);
     97 #ifdef LFS_READWRITE
     98 	/* XXX Eliminate me by using ufs_bufio in lfs.  */
     99 	if (vp->v_type == VREG && ip->i_number == LFS_IFILE_INUM)
    100 		return BUFRD(vp, uio, ioflag, ap->a_cred);
    101 #endif
    102 	if ((u_int64_t)uio->uio_offset > fs->um_maxfilesize)
    103 		return (EFBIG);
    104 	if (uio->uio_resid == 0)
    105 		return (0);
    106 
    107 #ifndef LFS_READWRITE
    108 	if ((ip->i_flags & (SF_SNAPSHOT | SF_SNAPINVAL)) == SF_SNAPSHOT)
    109 		return ffs_snapshot_read(vp, uio, ioflag);
    110 #endif /* !LFS_READWRITE */
    111 
    112 	fstrans_start(vp->v_mount, FSTRANS_SHARED);
    113 
    114 	if (uio->uio_offset >= ip->i_size)
    115 		goto out;
    116 
    117 	KASSERT(vp->v_type == VREG);
    118 	advice = IO_ADV_DECODE(ap->a_ioflag);
    119 	while (uio->uio_resid > 0) {
    120 		if (ioflag & IO_DIRECT) {
    121 			genfs_directio(vp, uio, ioflag);
    122 		}
    123 		bytelen = MIN(ip->i_size - uio->uio_offset, uio->uio_resid);
    124 		if (bytelen == 0)
    125 			break;
    126 		error = ubc_uiomove(&vp->v_uobj, uio, bytelen, advice,
    127 		    UBC_READ | UBC_PARTIALOK | UBC_UNMAP_FLAG(vp));
    128 		if (error)
    129 			break;
    130 	}
    131 
    132  out:
    133 	error = ulfs_post_read_update(vp, ap->a_ioflag, error);
    134 	fstrans_done(vp->v_mount);
    135 	return (error);
    136 }
    137 
    138 /*
    139  * UFS op for reading via the buffer cache
    140  */
    141 int
    142 BUFRD(struct vnode *vp, struct uio *uio, int ioflag, kauth_cred_t cred)
    143 {
    144 	struct inode *ip;
    145 	FS *fs;
    146 	struct buf *bp;
    147 	daddr_t lbn, nextlbn;
    148 	off_t bytesinfile;
    149 	long size, xfersize, blkoffset;
    150 	int error;
    151 
    152 	KASSERT(VOP_ISLOCKED(vp));
    153 	KASSERT(vp->v_type == VDIR || vp->v_type == VLNK ||
    154 	    vp->v_type == VREG);
    155 	KASSERT(uio->uio_rw == UIO_READ);
    156 
    157 	ip = VTOI(vp);
    158 	fs = ip->I_FS;
    159 	error = 0;
    160 
    161 	KASSERT(vp->v_type != VLNK || ip->i_size < fs->um_maxsymlinklen);
    162 	KASSERT(vp->v_type != VLNK || fs->um_maxsymlinklen != 0 ||
    163 	    DIP(ip, blocks) == 0);
    164 	KASSERT(vp->v_type != VREG || vp == fs->lfs_ivnode);
    165 	KASSERT(vp->v_type != VREG || ip->i_number == LFS_IFILE_INUM);
    166 
    167 	if (uio->uio_offset > fs->um_maxfilesize)
    168 		return EFBIG;
    169 	if (uio->uio_resid == 0)
    170 		return 0;
    171 
    172 #ifndef LFS_READWRITE
    173 	KASSERT(!ISSET(ip->i_flags, (SF_SNAPSHOT | SF_SNAPINVAL)));
    174 #endif
    175 
    176 	fstrans_start(vp->v_mount, FSTRANS_SHARED);
    177 
    178 	if (uio->uio_offset >= ip->i_size)
    179 		goto out;
    180 
    181 	for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
    182 		bytesinfile = ip->i_size - uio->uio_offset;
    183 		if (bytesinfile <= 0)
    184 			break;
    185 		lbn = lfs_lblkno(fs, uio->uio_offset);
    186 		nextlbn = lbn + 1;
    187 		size = lfs_blksize(fs, ip, lbn);
    188 		blkoffset = lfs_blkoff(fs, uio->uio_offset);
    189 		xfersize = MIN(MIN(fs->fs_bsize - blkoffset, uio->uio_resid),
    190 		    bytesinfile);
    191 
    192 		if (lfs_lblktosize(fs, nextlbn) >= ip->i_size)
    193 			error = bread(vp, lbn, size, NOCRED, 0, &bp);
    194 		else {
    195 			int nextsize = lfs_blksize(fs, ip, nextlbn);
    196 			error = breadn(vp, lbn,
    197 			    size, &nextlbn, &nextsize, 1, NOCRED, 0, &bp);
    198 		}
    199 		if (error)
    200 			break;
    201 
    202 		/*
    203 		 * We should only get non-zero b_resid when an I/O error
    204 		 * has occurred, which should cause us to break above.
    205 		 * However, if the short read did not cause an error,
    206 		 * then we want to ensure that we do not uiomove bad
    207 		 * or uninitialized data.
    208 		 */
    209 		size -= bp->b_resid;
    210 		if (size < xfersize) {
    211 			if (size == 0)
    212 				break;
    213 			xfersize = size;
    214 		}
    215 		error = uiomove((char *)bp->b_data + blkoffset, xfersize, uio);
    216 		if (error)
    217 			break;
    218 		brelse(bp, 0);
    219 	}
    220 	if (bp != NULL)
    221 		brelse(bp, 0);
    222 
    223  out:
    224 	error = ulfs_post_read_update(vp, ioflag, error);
    225 	fstrans_done(vp->v_mount);
    226 	return (error);
    227 }
    228 
    229 static int
    230 ulfs_post_read_update(struct vnode *vp, int ioflag, int error)
    231 {
    232 	struct inode *ip = VTOI(vp);
    233 
    234 	if (!(vp->v_mount->mnt_flag & MNT_NOATIME)) {
    235 		ip->i_flag |= IN_ACCESS;
    236 		if ((ioflag & IO_SYNC) == IO_SYNC) {
    237 			error = lfs_update(vp, NULL, NULL, UPDATE_WAIT);
    238 		}
    239 	}
    240 
    241 	return error;
    242 }
    243 
    244 /*
    245  * Vnode op for writing.
    246  */
    247 int
    248 WRITE(void *v)
    249 {
    250 	struct vop_write_args /* {
    251 		struct vnode *a_vp;
    252 		struct uio *a_uio;
    253 		int a_ioflag;
    254 		kauth_cred_t a_cred;
    255 	} */ *ap = v;
    256 	struct vnode *vp;
    257 	struct uio *uio;
    258 	struct inode *ip;
    259 	FS *fs;
    260 	kauth_cred_t cred;
    261 	off_t osize, origoff, oldoff, preallocoff, endallocoff, nsize;
    262 	int blkoffset, error, flags, ioflag, resid;
    263 	int aflag;
    264 	int extended=0;
    265 	vsize_t bytelen;
    266 	bool async;
    267 
    268 	cred = ap->a_cred;
    269 	ioflag = ap->a_ioflag;
    270 	uio = ap->a_uio;
    271 	vp = ap->a_vp;
    272 	ip = VTOI(vp);
    273 
    274 	KASSERT(vp->v_size == ip->i_size);
    275 	KASSERT(uio->uio_rw == UIO_WRITE);
    276 	KASSERT(vp->v_type == VREG);
    277 
    278 	if (ioflag & IO_APPEND)
    279 		uio->uio_offset = ip->i_size;
    280 	if ((ip->i_flags & APPEND) && uio->uio_offset != ip->i_size)
    281 		return (EPERM);
    282 
    283 	fs = ip->I_FS;
    284 	if (uio->uio_offset < 0 ||
    285 	    (u_int64_t)uio->uio_offset + uio->uio_resid > fs->um_maxfilesize)
    286 		return (EFBIG);
    287 #ifdef LFS_READWRITE
    288 	/* Disallow writes to the Ifile, even if noschg flag is removed */
    289 	/* XXX can this go away when the Ifile is no longer in the namespace? */
    290 	if (vp == fs->lfs_ivnode)
    291 		return (EPERM);
    292 #endif
    293 	if (uio->uio_resid == 0)
    294 		return (0);
    295 
    296 	fstrans_start(vp->v_mount, FSTRANS_SHARED);
    297 
    298 	flags = ioflag & IO_SYNC ? B_SYNC : 0;
    299 	async = vp->v_mount->mnt_flag & MNT_ASYNC;
    300 	origoff = uio->uio_offset;
    301 	resid = uio->uio_resid;
    302 	osize = ip->i_size;
    303 	error = 0;
    304 
    305 	KASSERT(vp->v_type == VREG);
    306 
    307 #ifdef LFS_READWRITE
    308 	async = true;
    309 	lfs_availwait(fs, lfs_btofsb(fs, uio->uio_resid));
    310 	lfs_check(vp, LFS_UNUSED_LBN, 0);
    311 #endif /* !LFS_READWRITE */
    312 
    313 	preallocoff = round_page(lfs_blkroundup(fs, MAX(osize, uio->uio_offset)));
    314 	aflag = ioflag & IO_SYNC ? B_SYNC : 0;
    315 	nsize = MAX(osize, uio->uio_offset + uio->uio_resid);
    316 	endallocoff = nsize - lfs_blkoff(fs, nsize);
    317 
    318 	/*
    319 	 * if we're increasing the file size, deal with expanding
    320 	 * the fragment if there is one.
    321 	 */
    322 
    323 	if (nsize > osize && lfs_lblkno(fs, osize) < ULFS_NDADDR &&
    324 	    lfs_lblkno(fs, osize) != lfs_lblkno(fs, nsize) &&
    325 	    lfs_blkroundup(fs, osize) != osize) {
    326 		off_t eob;
    327 
    328 		eob = lfs_blkroundup(fs, osize);
    329 		uvm_vnp_setwritesize(vp, eob);
    330 		error = ulfs_balloc_range(vp, osize, eob - osize, cred, aflag);
    331 		if (error)
    332 			goto out;
    333 		if (flags & B_SYNC) {
    334 			mutex_enter(vp->v_interlock);
    335 			VOP_PUTPAGES(vp, trunc_page(osize & fs->fs_bmask),
    336 			    round_page(eob),
    337 			    PGO_CLEANIT | PGO_SYNCIO | PGO_JOURNALLOCKED);
    338 		}
    339 	}
    340 
    341 	while (uio->uio_resid > 0) {
    342 		int ubc_flags = UBC_WRITE;
    343 		bool overwrite; /* if we're overwrite a whole block */
    344 		off_t newoff;
    345 
    346 		if (ioflag & IO_DIRECT) {
    347 			genfs_directio(vp, uio, ioflag | IO_JOURNALLOCKED);
    348 		}
    349 
    350 		oldoff = uio->uio_offset;
    351 		blkoffset = lfs_blkoff(fs, uio->uio_offset);
    352 		bytelen = MIN(fs->fs_bsize - blkoffset, uio->uio_resid);
    353 		if (bytelen == 0) {
    354 			break;
    355 		}
    356 
    357 		/*
    358 		 * if we're filling in a hole, allocate the blocks now and
    359 		 * initialize the pages first.  if we're extending the file,
    360 		 * we can safely allocate blocks without initializing pages
    361 		 * since the new blocks will be inaccessible until the write
    362 		 * is complete.
    363 		 */
    364 		overwrite = uio->uio_offset >= preallocoff &&
    365 		    uio->uio_offset < endallocoff;
    366 		if (!overwrite && (vp->v_vflag & VV_MAPPED) == 0 &&
    367 		    lfs_blkoff(fs, uio->uio_offset) == 0 &&
    368 		    (uio->uio_offset & PAGE_MASK) == 0) {
    369 			vsize_t len;
    370 
    371 			len = trunc_page(bytelen);
    372 			len -= lfs_blkoff(fs, len);
    373 			if (len > 0) {
    374 				overwrite = true;
    375 				bytelen = len;
    376 			}
    377 		}
    378 
    379 		newoff = oldoff + bytelen;
    380 		if (vp->v_size < newoff) {
    381 			uvm_vnp_setwritesize(vp, newoff);
    382 		}
    383 
    384 		if (!overwrite) {
    385 			error = ulfs_balloc_range(vp, uio->uio_offset, bytelen,
    386 			    cred, aflag);
    387 			if (error)
    388 				break;
    389 		} else {
    390 			genfs_node_wrlock(vp);
    391 			error = GOP_ALLOC(vp, uio->uio_offset, bytelen,
    392 			    aflag, cred);
    393 			genfs_node_unlock(vp);
    394 			if (error)
    395 				break;
    396 			ubc_flags |= UBC_FAULTBUSY;
    397 		}
    398 
    399 		/*
    400 		 * copy the data.
    401 		 */
    402 
    403 		error = ubc_uiomove(&vp->v_uobj, uio, bytelen,
    404 		    IO_ADV_DECODE(ioflag), ubc_flags | UBC_UNMAP_FLAG(vp));
    405 
    406 		/*
    407 		 * update UVM's notion of the size now that we've
    408 		 * copied the data into the vnode's pages.
    409 		 *
    410 		 * we should update the size even when uiomove failed.
    411 		 */
    412 
    413 		if (vp->v_size < newoff) {
    414 			uvm_vnp_setsize(vp, newoff);
    415 			extended = 1;
    416 		}
    417 
    418 		if (error)
    419 			break;
    420 
    421 		/*
    422 		 * flush what we just wrote if necessary.
    423 		 * XXXUBC simplistic async flushing.
    424 		 */
    425 
    426 #ifndef LFS_READWRITE
    427 		if (!async && oldoff >> 16 != uio->uio_offset >> 16) {
    428 			mutex_enter(vp->v_interlock);
    429 			error = VOP_PUTPAGES(vp, (oldoff >> 16) << 16,
    430 			    (uio->uio_offset >> 16) << 16,
    431 			    PGO_CLEANIT | PGO_JOURNALLOCKED | PGO_LAZY);
    432 			if (error)
    433 				break;
    434 		}
    435 #else
    436 		__USE(async);
    437 #endif
    438 	}
    439 	if (error == 0 && ioflag & IO_SYNC) {
    440 		mutex_enter(vp->v_interlock);
    441 		error = VOP_PUTPAGES(vp, trunc_page(origoff & fs->fs_bmask),
    442 		    round_page(lfs_blkroundup(fs, uio->uio_offset)),
    443 		    PGO_CLEANIT | PGO_SYNCIO | PGO_JOURNALLOCKED);
    444 	}
    445 
    446 out:
    447 	error = ulfs_post_write_update(vp, uio, ioflag, cred, osize, resid,
    448 	    extended, error);
    449 	fstrans_done(vp->v_mount);
    450 
    451 	return (error);
    452 }
    453 
    454 /*
    455  * UFS op for writing via the buffer cache
    456  */
    457 int
    458 BUFWR(struct vnode *vp, struct uio *uio, int ioflag, kauth_cred_t cred)
    459 {
    460 	struct inode *ip;
    461 	FS *fs;
    462 	int flags;
    463 	struct buf *bp;
    464 	off_t osize, origoff;
    465 	int resid, xfersize, size, blkoffset;
    466 	daddr_t lbn;
    467 	int extended=0;
    468 	int error;
    469 #ifdef LFS_READWRITE
    470 	bool need_unreserve = false;
    471 #endif
    472 
    473 	KASSERT(ISSET(ioflag, IO_NODELOCKED));
    474 	KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);
    475 	KASSERT(vp->v_type == VDIR || vp->v_type == VLNK);
    476 	KASSERT(vp->v_type != VDIR || ISSET(ioflag, IO_SYNC));
    477 	KASSERT(uio->uio_rw == UIO_WRITE);
    478 
    479 	ip = VTOI(vp);
    480 	fs = ip->I_FS;
    481 
    482 	KASSERT(vp->v_size == ip->i_size);
    483 
    484 	if (uio->uio_offset < 0 ||
    485 	    uio->uio_resid > fs->um_maxfilesize ||
    486 	    uio->uio_offset > (fs->um_maxfilesize - uio->uio_resid))
    487 		return EFBIG;
    488 #ifdef LFS_READWRITE
    489 	KASSERT(vp != fs->lfs_ivnode);
    490 #endif
    491 	if (uio->uio_resid == 0)
    492 		return 0;
    493 
    494 	fstrans_start(vp->v_mount, FSTRANS_SHARED);
    495 
    496 	flags = ioflag & IO_SYNC ? B_SYNC : 0;
    497 	origoff = uio->uio_offset;
    498 	resid = uio->uio_resid;
    499 	osize = ip->i_size;
    500 	error = 0;
    501 
    502 	KASSERT(vp->v_type != VREG);
    503 
    504 #ifdef LFS_READWRITE
    505 	lfs_availwait(fs, lfs_btofsb(fs, uio->uio_resid));
    506 	lfs_check(vp, LFS_UNUSED_LBN, 0);
    507 #endif /* !LFS_READWRITE */
    508 
    509 	/* XXX Should never have pages cached here.  */
    510 	mutex_enter(vp->v_interlock);
    511 	VOP_PUTPAGES(vp, trunc_page(origoff), round_page(origoff + resid),
    512 	    PGO_CLEANIT | PGO_FREE | PGO_SYNCIO | PGO_JOURNALLOCKED);
    513 	while (uio->uio_resid > 0) {
    514 		lbn = lfs_lblkno(fs, uio->uio_offset);
    515 		blkoffset = lfs_blkoff(fs, uio->uio_offset);
    516 		xfersize = MIN(fs->fs_bsize - blkoffset, uio->uio_resid);
    517 		if (fs->fs_bsize > xfersize)
    518 			flags |= B_CLRBUF;
    519 		else
    520 			flags &= ~B_CLRBUF;
    521 
    522 #ifdef LFS_READWRITE
    523 		error = lfs_reserve(fs, vp, NULL,
    524 		    lfs_btofsb(fs, (ULFS_NIADDR + 1) << fs->lfs_bshift));
    525 		if (error)
    526 			break;
    527 		need_unreserve = true;
    528 #endif
    529 		error = lfs_balloc(vp, uio->uio_offset, xfersize, cred, flags,
    530 		    &bp);
    531 
    532 		if (error)
    533 			break;
    534 		if (uio->uio_offset + xfersize > ip->i_size) {
    535 			ip->i_size = uio->uio_offset + xfersize;
    536 			DIP_ASSIGN(ip, size, ip->i_size);
    537 			uvm_vnp_setsize(vp, ip->i_size);
    538 			extended = 1;
    539 		}
    540 		size = lfs_blksize(fs, ip, lbn) - bp->b_resid;
    541 		if (xfersize > size)
    542 			xfersize = size;
    543 
    544 		error = uiomove((char *)bp->b_data + blkoffset, xfersize, uio);
    545 
    546 		/*
    547 		 * if we didn't clear the block and the uiomove failed,
    548 		 * the buf will now contain part of some other file,
    549 		 * so we need to invalidate it.
    550 		 */
    551 		if (error && (flags & B_CLRBUF) == 0) {
    552 			brelse(bp, BC_INVAL);
    553 			break;
    554 		}
    555 #ifdef LFS_READWRITE
    556 		(void)VOP_BWRITE(bp->b_vp, bp);
    557 		lfs_reserve(fs, vp, NULL,
    558 		    -lfs_btofsb(fs, (ULFS_NIADDR + 1) << fs->lfs_bshift));
    559 		need_unreserve = false;
    560 #else
    561 		if (ioflag & IO_SYNC)
    562 			(void)bwrite(bp);
    563 		else if (xfersize + blkoffset == fs->fs_bsize)
    564 			bawrite(bp);
    565 		else
    566 			bdwrite(bp);
    567 #endif
    568 		if (error || xfersize == 0)
    569 			break;
    570 	}
    571 #ifdef LFS_READWRITE
    572 	if (need_unreserve) {
    573 		lfs_reserve(fs, vp, NULL,
    574 		    -lfs_btofsb(fs, (ULFS_NIADDR + 1) << fs->lfs_bshift));
    575 	}
    576 #endif
    577 
    578 	error = ulfs_post_write_update(vp, uio, ioflag, cred, osize, resid,
    579 	    extended, error);
    580 	fstrans_done(vp->v_mount);
    581 
    582 	return (error);
    583 }
    584 
    585 static int
    586 ulfs_post_write_update(struct vnode *vp, struct uio *uio, int ioflag,
    587     kauth_cred_t cred, off_t osize, int resid, int extended, int error)
    588 {
    589 	struct inode *ip = VTOI(vp);
    590 
    591 	/* Trigger ctime and mtime updates, and atime if MNT_RELATIME.  */
    592 	ip->i_flag |= IN_CHANGE | IN_UPDATE;
    593 	if (vp->v_mount->mnt_flag & MNT_RELATIME)
    594 		ip->i_flag |= IN_ACCESS;
    595 
    596 	/*
    597 	 * If we successfully wrote any data and we are not the superuser,
    598 	 * we clear the setuid and setgid bits as a precaution against
    599 	 * tampering.
    600 	 */
    601 	if (resid > uio->uio_resid && cred) {
    602 		if (ip->i_mode & ISUID) {
    603 			if (kauth_authorize_vnode(cred,
    604 			    KAUTH_VNODE_RETAIN_SUID, vp, NULL, EPERM) != 0) {
    605 				ip->i_mode &= ~ISUID;
    606 				DIP_ASSIGN(ip, mode, ip->i_mode);
    607 			}
    608 		}
    609 
    610 		if (ip->i_mode & ISGID) {
    611 			if (kauth_authorize_vnode(cred,
    612 			    KAUTH_VNODE_RETAIN_SGID, vp, NULL, EPERM) != 0) {
    613 				ip->i_mode &= ~ISGID;
    614 				DIP_ASSIGN(ip, mode, ip->i_mode);
    615 			}
    616 		}
    617 	}
    618 
    619 	/* If we successfully wrote anything, notify kevent listeners.  */
    620 	if (resid > uio->uio_resid)
    621 		VN_KNOTE(vp, NOTE_WRITE | (extended ? NOTE_EXTEND : 0));
    622 
    623 	/*
    624 	 * Update the size on disk: truncate back to original size on
    625 	 * error, or reflect the new size on success.
    626 	 */
    627 	if (error) {
    628 		(void) lfs_truncate(vp, osize, ioflag & IO_SYNC, cred);
    629 		uio->uio_offset -= resid - uio->uio_resid;
    630 		uio->uio_resid = resid;
    631 	} else if (resid > uio->uio_resid && (ioflag & IO_SYNC) == IO_SYNC) {
    632 		error = lfs_update(vp, NULL, NULL, UPDATE_WAIT);
    633 	} else {
    634 		/* nothing */
    635 	}
    636 
    637 	/* Make sure the vnode uvm size matches the inode file size.  */
    638 	KASSERT(vp->v_size == ip->i_size);
    639 
    640 	return error;
    641 }
    642