The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_vnops.c

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * (c) UNIX System Laboratories, Inc.
    5  * All or some portions of this file are derived from material licensed
    6  * to the University of California by American Telephone and Telegraph
    7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    8  * the permission of UNIX System Laboratories, Inc.
    9  *
   10  * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
   11  * Copyright (c) 2013, 2014 The FreeBSD Foundation
   12  *
   13  * Portions of this software were developed by Konstantin Belousov
   14  * under sponsorship from the FreeBSD Foundation.
   15  *
   16  * Redistribution and use in source and binary forms, with or without
   17  * modification, are permitted provided that the following conditions
   18  * are met:
   19  * 1. Redistributions of source code must retain the above copyright
   20  *    notice, this list of conditions and the following disclaimer.
   21  * 2. Redistributions in binary form must reproduce the above copyright
   22  *    notice, this list of conditions and the following disclaimer in the
   23  *    documentation and/or other materials provided with the distribution.
   24  * 4. Neither the name of the University nor the names of its contributors
   25  *    may be used to endorse or promote products derived from this software
   26  *    without specific prior written permission.
   27  *
   28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   38  * SUCH DAMAGE.
   39  *
   40  *      @(#)vfs_vnops.c 8.2 (Berkeley) 1/21/94
   41  */
   42 
   43 #include <sys/cdefs.h>
   44 __FBSDID("$FreeBSD: releng/11.0/sys/kern/vfs_vnops.c 302345 2016-07-05 16:37:01Z rwatson $");
   45 
   46 #include "opt_hwpmc_hooks.h"
   47 
   48 #include <sys/param.h>
   49 #include <sys/systm.h>
   50 #include <sys/disk.h>
   51 #include <sys/fail.h>
   52 #include <sys/fcntl.h>
   53 #include <sys/file.h>
   54 #include <sys/kdb.h>
   55 #include <sys/stat.h>
   56 #include <sys/priv.h>
   57 #include <sys/proc.h>
   58 #include <sys/limits.h>
   59 #include <sys/lock.h>
   60 #include <sys/mman.h>
   61 #include <sys/mount.h>
   62 #include <sys/mutex.h>
   63 #include <sys/namei.h>
   64 #include <sys/vnode.h>
   65 #include <sys/bio.h>
   66 #include <sys/buf.h>
   67 #include <sys/filio.h>
   68 #include <sys/resourcevar.h>
   69 #include <sys/rwlock.h>
   70 #include <sys/sx.h>
   71 #include <sys/sysctl.h>
   72 #include <sys/ttycom.h>
   73 #include <sys/conf.h>
   74 #include <sys/syslog.h>
   75 #include <sys/unistd.h>
   76 #include <sys/user.h>
   77 
   78 #include <security/audit/audit.h>
   79 #include <security/mac/mac_framework.h>
   80 
   81 #include <vm/vm.h>
   82 #include <vm/vm_extern.h>
   83 #include <vm/pmap.h>
   84 #include <vm/vm_map.h>
   85 #include <vm/vm_object.h>
   86 #include <vm/vm_page.h>
   87 #include <vm/vnode_pager.h>
   88 
   89 #ifdef HWPMC_HOOKS
   90 #include <sys/pmckern.h>
   91 #endif
   92 
   93 static fo_rdwr_t        vn_read;
   94 static fo_rdwr_t        vn_write;
   95 static fo_rdwr_t        vn_io_fault;
   96 static fo_truncate_t    vn_truncate;
   97 static fo_ioctl_t       vn_ioctl;
   98 static fo_poll_t        vn_poll;
   99 static fo_kqfilter_t    vn_kqfilter;
  100 static fo_stat_t        vn_statfile;
  101 static fo_close_t       vn_closefile;
  102 static fo_mmap_t        vn_mmap;
  103 
  104 struct  fileops vnops = {
  105         .fo_read = vn_io_fault,
  106         .fo_write = vn_io_fault,
  107         .fo_truncate = vn_truncate,
  108         .fo_ioctl = vn_ioctl,
  109         .fo_poll = vn_poll,
  110         .fo_kqfilter = vn_kqfilter,
  111         .fo_stat = vn_statfile,
  112         .fo_close = vn_closefile,
  113         .fo_chmod = vn_chmod,
  114         .fo_chown = vn_chown,
  115         .fo_sendfile = vn_sendfile,
  116         .fo_seek = vn_seek,
  117         .fo_fill_kinfo = vn_fill_kinfo,
  118         .fo_mmap = vn_mmap,
  119         .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE
  120 };
  121 
  122 static const int io_hold_cnt = 16;
  123 static int vn_io_fault_enable = 1;
  124 SYSCTL_INT(_debug, OID_AUTO, vn_io_fault_enable, CTLFLAG_RW,
  125     &vn_io_fault_enable, 0, "Enable vn_io_fault lock avoidance");
  126 static int vn_io_fault_prefault = 0;
  127 SYSCTL_INT(_debug, OID_AUTO, vn_io_fault_prefault, CTLFLAG_RW,
  128     &vn_io_fault_prefault, 0, "Enable vn_io_fault prefaulting");
  129 static u_long vn_io_faults_cnt;
  130 SYSCTL_ULONG(_debug, OID_AUTO, vn_io_faults, CTLFLAG_RD,
  131     &vn_io_faults_cnt, 0, "Count of vn_io_fault lock avoidance triggers");
  132 
  133 /*
  134  * Returns true if vn_io_fault mode of handling the i/o request should
  135  * be used.
  136  */
  137 static bool
  138 do_vn_io_fault(struct vnode *vp, struct uio *uio)
  139 {
  140         struct mount *mp;
  141 
  142         return (uio->uio_segflg == UIO_USERSPACE && vp->v_type == VREG &&
  143             (mp = vp->v_mount) != NULL &&
  144             (mp->mnt_kern_flag & MNTK_NO_IOPF) != 0 && vn_io_fault_enable);
  145 }
  146 
  147 /*
  148  * Structure used to pass arguments to vn_io_fault1(), to do either
  149  * file- or vnode-based I/O calls.
  150  */
  151 struct vn_io_fault_args {
  152         enum {
  153                 VN_IO_FAULT_FOP,
  154                 VN_IO_FAULT_VOP
  155         } kind;
  156         struct ucred *cred;
  157         int flags;
  158         union {
  159                 struct fop_args_tag {
  160                         struct file *fp;
  161                         fo_rdwr_t *doio;
  162                 } fop_args;
  163                 struct vop_args_tag {
  164                         struct vnode *vp;
  165                 } vop_args;
  166         } args;
  167 };
  168 
  169 static int vn_io_fault1(struct vnode *vp, struct uio *uio,
  170     struct vn_io_fault_args *args, struct thread *td);
  171 
  172 int
  173 vn_open(ndp, flagp, cmode, fp)
  174         struct nameidata *ndp;
  175         int *flagp, cmode;
  176         struct file *fp;
  177 {
  178         struct thread *td = ndp->ni_cnd.cn_thread;
  179 
  180         return (vn_open_cred(ndp, flagp, cmode, 0, td->td_ucred, fp));
  181 }
  182 
  183 /*
  184  * Common code for vnode open operations via a name lookup.
  185  * Lookup the vnode and invoke VOP_CREATE if needed.
  186  * Check permissions, and call the VOP_OPEN or VOP_CREATE routine.
  187  * 
  188  * Note that this does NOT free nameidata for the successful case,
  189  * due to the NDINIT being done elsewhere.
  190  */
  191 int
  192 vn_open_cred(struct nameidata *ndp, int *flagp, int cmode, u_int vn_open_flags,
  193     struct ucred *cred, struct file *fp)
  194 {
  195         struct vnode *vp;
  196         struct mount *mp;
  197         struct thread *td = ndp->ni_cnd.cn_thread;
  198         struct vattr vat;
  199         struct vattr *vap = &vat;
  200         int fmode, error;
  201 
  202 restart:
  203         fmode = *flagp;
  204         if ((fmode & (O_CREAT | O_EXCL | O_DIRECTORY)) == (O_CREAT |
  205             O_EXCL | O_DIRECTORY))
  206                 return (EINVAL);
  207         else if ((fmode & (O_CREAT | O_DIRECTORY)) == O_CREAT) {
  208                 ndp->ni_cnd.cn_nameiop = CREATE;
  209                 /*
  210                  * Set NOCACHE to avoid flushing the cache when
  211                  * rolling in many files at once.
  212                 */
  213                 ndp->ni_cnd.cn_flags = ISOPEN | LOCKPARENT | LOCKLEAF | NOCACHE;
  214                 if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
  215                         ndp->ni_cnd.cn_flags |= FOLLOW;
  216                 if (!(vn_open_flags & VN_OPEN_NOAUDIT))
  217                         ndp->ni_cnd.cn_flags |= AUDITVNODE1;
  218                 if (vn_open_flags & VN_OPEN_NOCAPCHECK)
  219                         ndp->ni_cnd.cn_flags |= NOCAPCHECK;
  220                 bwillwrite();
  221                 if ((error = namei(ndp)) != 0)
  222                         return (error);
  223                 if (ndp->ni_vp == NULL) {
  224                         VATTR_NULL(vap);
  225                         vap->va_type = VREG;
  226                         vap->va_mode = cmode;
  227                         if (fmode & O_EXCL)
  228                                 vap->va_vaflags |= VA_EXCLUSIVE;
  229                         if (vn_start_write(ndp->ni_dvp, &mp, V_NOWAIT) != 0) {
  230                                 NDFREE(ndp, NDF_ONLY_PNBUF);
  231                                 vput(ndp->ni_dvp);
  232                                 if ((error = vn_start_write(NULL, &mp,
  233                                     V_XSLEEP | PCATCH)) != 0)
  234                                         return (error);
  235                                 goto restart;
  236                         }
  237                         if ((vn_open_flags & VN_OPEN_NAMECACHE) != 0)
  238                                 ndp->ni_cnd.cn_flags |= MAKEENTRY;
  239 #ifdef MAC
  240                         error = mac_vnode_check_create(cred, ndp->ni_dvp,
  241                             &ndp->ni_cnd, vap);
  242                         if (error == 0)
  243 #endif
  244                                 error = VOP_CREATE(ndp->ni_dvp, &ndp->ni_vp,
  245                                                    &ndp->ni_cnd, vap);
  246                         vput(ndp->ni_dvp);
  247                         vn_finished_write(mp);
  248                         if (error) {
  249                                 NDFREE(ndp, NDF_ONLY_PNBUF);
  250                                 return (error);
  251                         }
  252                         fmode &= ~O_TRUNC;
  253                         vp = ndp->ni_vp;
  254                 } else {
  255                         if (ndp->ni_dvp == ndp->ni_vp)
  256                                 vrele(ndp->ni_dvp);
  257                         else
  258                                 vput(ndp->ni_dvp);
  259                         ndp->ni_dvp = NULL;
  260                         vp = ndp->ni_vp;
  261                         if (fmode & O_EXCL) {
  262                                 error = EEXIST;
  263                                 goto bad;
  264                         }
  265                         fmode &= ~O_CREAT;
  266                 }
  267         } else {
  268                 ndp->ni_cnd.cn_nameiop = LOOKUP;
  269                 ndp->ni_cnd.cn_flags = ISOPEN |
  270                     ((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) | LOCKLEAF;
  271                 if (!(fmode & FWRITE))
  272                         ndp->ni_cnd.cn_flags |= LOCKSHARED;
  273                 if (!(vn_open_flags & VN_OPEN_NOAUDIT))
  274                         ndp->ni_cnd.cn_flags |= AUDITVNODE1;
  275                 if (vn_open_flags & VN_OPEN_NOCAPCHECK)
  276                         ndp->ni_cnd.cn_flags |= NOCAPCHECK;
  277                 if ((error = namei(ndp)) != 0)
  278                         return (error);
  279                 vp = ndp->ni_vp;
  280         }
  281         error = vn_open_vnode(vp, fmode, cred, td, fp);
  282         if (error)
  283                 goto bad;
  284         *flagp = fmode;
  285         return (0);
  286 bad:
  287         NDFREE(ndp, NDF_ONLY_PNBUF);
  288         vput(vp);
  289         *flagp = fmode;
  290         ndp->ni_vp = NULL;
  291         return (error);
  292 }
  293 
  294 /*
  295  * Common code for vnode open operations once a vnode is located.
  296  * Check permissions, and call the VOP_OPEN routine.
  297  */
  298 int
  299 vn_open_vnode(struct vnode *vp, int fmode, struct ucred *cred,
  300     struct thread *td, struct file *fp)
  301 {
  302         accmode_t accmode;
  303         struct flock lf;
  304         int error, lock_flags, type;
  305 
  306         if (vp->v_type == VLNK)
  307                 return (EMLINK);
  308         if (vp->v_type == VSOCK)
  309                 return (EOPNOTSUPP);
  310         if (vp->v_type != VDIR && fmode & O_DIRECTORY)
  311                 return (ENOTDIR);
  312         accmode = 0;
  313         if (fmode & (FWRITE | O_TRUNC)) {
  314                 if (vp->v_type == VDIR)
  315                         return (EISDIR);
  316                 accmode |= VWRITE;
  317         }
  318         if (fmode & FREAD)
  319                 accmode |= VREAD;
  320         if (fmode & FEXEC)
  321                 accmode |= VEXEC;
  322         if ((fmode & O_APPEND) && (fmode & FWRITE))
  323                 accmode |= VAPPEND;
  324 #ifdef MAC
  325         if (fmode & O_CREAT)
  326                 accmode |= VCREAT;
  327         if (fmode & O_VERIFY)
  328                 accmode |= VVERIFY;
  329         error = mac_vnode_check_open(cred, vp, accmode);
  330         if (error)
  331                 return (error);
  332 
  333         accmode &= ~(VCREAT | VVERIFY);
  334 #endif
  335         if ((fmode & O_CREAT) == 0) {
  336                 if (accmode & VWRITE) {
  337                         error = vn_writechk(vp);
  338                         if (error)
  339                                 return (error);
  340                 }
  341                 if (accmode) {
  342                         error = VOP_ACCESS(vp, accmode, cred, td);
  343                         if (error)
  344                                 return (error);
  345                 }
  346         }
  347         if (vp->v_type == VFIFO && VOP_ISLOCKED(vp) != LK_EXCLUSIVE)
  348                 vn_lock(vp, LK_UPGRADE | LK_RETRY);
  349         if ((error = VOP_OPEN(vp, fmode, cred, td, fp)) != 0)
  350                 return (error);
  351 
  352         if (fmode & (O_EXLOCK | O_SHLOCK)) {
  353                 KASSERT(fp != NULL, ("open with flock requires fp"));
  354                 lock_flags = VOP_ISLOCKED(vp);
  355                 VOP_UNLOCK(vp, 0);
  356                 lf.l_whence = SEEK_SET;
  357                 lf.l_start = 0;
  358                 lf.l_len = 0;
  359                 if (fmode & O_EXLOCK)
  360                         lf.l_type = F_WRLCK;
  361                 else
  362                         lf.l_type = F_RDLCK;
  363                 type = F_FLOCK;
  364                 if ((fmode & FNONBLOCK) == 0)
  365                         type |= F_WAIT;
  366                 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, type);
  367                 if (error == 0)
  368                         fp->f_flag |= FHASLOCK;
  369                 vn_lock(vp, lock_flags | LK_RETRY);
  370                 if (error == 0 && vp->v_iflag & VI_DOOMED)
  371                         error = ENOENT;
  372 
  373                 /*
  374                  * Another thread might have used this vnode as an
  375                  * executable while the vnode lock was dropped.
  376                  * Ensure the vnode is still able to be opened for
  377                  * writing after the lock has been obtained.
  378                  */
  379                 if (error == 0 && accmode & VWRITE)
  380                         error = vn_writechk(vp);
  381 
  382                 if (error != 0) {
  383                         fp->f_flag |= FOPENFAILED;
  384                         fp->f_vnode = vp;
  385                         if (fp->f_ops == &badfileops) {
  386                                 fp->f_type = DTYPE_VNODE;
  387                                 fp->f_ops = &vnops;
  388                         }
  389                         vref(vp);
  390                 }
  391         }
  392         if (error == 0 && fmode & FWRITE) {
  393                 VOP_ADD_WRITECOUNT(vp, 1);
  394                 CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d",
  395                     __func__, vp, vp->v_writecount);
  396         }
  397         ASSERT_VOP_LOCKED(vp, "vn_open_vnode");
  398         return (error);
  399 }
  400 
  401 /*
  402  * Check for write permissions on the specified vnode.
  403  * Prototype text segments cannot be written.
  404  */
  405 int
  406 vn_writechk(vp)
  407         register struct vnode *vp;
  408 {
  409 
  410         ASSERT_VOP_LOCKED(vp, "vn_writechk");
  411         /*
  412          * If there's shared text associated with
  413          * the vnode, try to free it up once.  If
  414          * we fail, we can't allow writing.
  415          */
  416         if (VOP_IS_TEXT(vp))
  417                 return (ETXTBSY);
  418 
  419         return (0);
  420 }
  421 
  422 /*
  423  * Vnode close call
  424  */
  425 int
  426 vn_close(vp, flags, file_cred, td)
  427         register struct vnode *vp;
  428         int flags;
  429         struct ucred *file_cred;
  430         struct thread *td;
  431 {
  432         struct mount *mp;
  433         int error, lock_flags;
  434 
  435         if (vp->v_type != VFIFO && (flags & FWRITE) == 0 &&
  436             MNT_EXTENDED_SHARED(vp->v_mount))
  437                 lock_flags = LK_SHARED;
  438         else
  439                 lock_flags = LK_EXCLUSIVE;
  440 
  441         vn_start_write(vp, &mp, V_WAIT);
  442         vn_lock(vp, lock_flags | LK_RETRY);
  443         AUDIT_ARG_VNODE1(vp);
  444         if ((flags & (FWRITE | FOPENFAILED)) == FWRITE) {
  445                 VNASSERT(vp->v_writecount > 0, vp, 
  446                     ("vn_close: negative writecount"));
  447                 VOP_ADD_WRITECOUNT(vp, -1);
  448                 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
  449                     __func__, vp, vp->v_writecount);
  450         }
  451         error = VOP_CLOSE(vp, flags, file_cred, td);
  452         vput(vp);
  453         vn_finished_write(mp);
  454         return (error);
  455 }
  456 
  457 /*
  458  * Heuristic to detect sequential operation.
  459  */
  460 static int
  461 sequential_heuristic(struct uio *uio, struct file *fp)
  462 {
  463 
  464         ASSERT_VOP_LOCKED(fp->f_vnode, __func__);
  465         if (fp->f_flag & FRDAHEAD)
  466                 return (fp->f_seqcount << IO_SEQSHIFT);
  467 
  468         /*
  469          * Offset 0 is handled specially.  open() sets f_seqcount to 1 so
  470          * that the first I/O is normally considered to be slightly
  471          * sequential.  Seeking to offset 0 doesn't change sequentiality
  472          * unless previous seeks have reduced f_seqcount to 0, in which
  473          * case offset 0 is not special.
  474          */
  475         if ((uio->uio_offset == 0 && fp->f_seqcount > 0) ||
  476             uio->uio_offset == fp->f_nextoff) {
  477                 /*
  478                  * f_seqcount is in units of fixed-size blocks so that it
  479                  * depends mainly on the amount of sequential I/O and not
  480                  * much on the number of sequential I/O's.  The fixed size
  481                  * of 16384 is hard-coded here since it is (not quite) just
  482                  * a magic size that works well here.  This size is more
  483                  * closely related to the best I/O size for real disks than
  484                  * to any block size used by software.
  485                  */
  486                 fp->f_seqcount += howmany(uio->uio_resid, 16384);
  487                 if (fp->f_seqcount > IO_SEQMAX)
  488                         fp->f_seqcount = IO_SEQMAX;
  489                 return (fp->f_seqcount << IO_SEQSHIFT);
  490         }
  491 
  492         /* Not sequential.  Quickly draw-down sequentiality. */
  493         if (fp->f_seqcount > 1)
  494                 fp->f_seqcount = 1;
  495         else
  496                 fp->f_seqcount = 0;
  497         return (0);
  498 }
  499 
  500 /*
  501  * Package up an I/O request on a vnode into a uio and do it.
  502  */
  503 int
  504 vn_rdwr(enum uio_rw rw, struct vnode *vp, void *base, int len, off_t offset,
  505     enum uio_seg segflg, int ioflg, struct ucred *active_cred,
  506     struct ucred *file_cred, ssize_t *aresid, struct thread *td)
  507 {
  508         struct uio auio;
  509         struct iovec aiov;
  510         struct mount *mp;
  511         struct ucred *cred;
  512         void *rl_cookie;
  513         struct vn_io_fault_args args;
  514         int error, lock_flags;
  515 
  516         auio.uio_iov = &aiov;
  517         auio.uio_iovcnt = 1;
  518         aiov.iov_base = base;
  519         aiov.iov_len = len;
  520         auio.uio_resid = len;
  521         auio.uio_offset = offset;
  522         auio.uio_segflg = segflg;
  523         auio.uio_rw = rw;
  524         auio.uio_td = td;
  525         error = 0;
  526 
  527         if ((ioflg & IO_NODELOCKED) == 0) {
  528                 if ((ioflg & IO_RANGELOCKED) == 0) {
  529                         if (rw == UIO_READ) {
  530                                 rl_cookie = vn_rangelock_rlock(vp, offset,
  531                                     offset + len);
  532                         } else {
  533                                 rl_cookie = vn_rangelock_wlock(vp, offset,
  534                                     offset + len);
  535                         }
  536                 } else
  537                         rl_cookie = NULL;
  538                 mp = NULL;
  539                 if (rw == UIO_WRITE) { 
  540                         if (vp->v_type != VCHR &&
  541                             (error = vn_start_write(vp, &mp, V_WAIT | PCATCH))
  542                             != 0)
  543                                 goto out;
  544                         if (MNT_SHARED_WRITES(mp) ||
  545                             ((mp == NULL) && MNT_SHARED_WRITES(vp->v_mount)))
  546                                 lock_flags = LK_SHARED;
  547                         else
  548                                 lock_flags = LK_EXCLUSIVE;
  549                 } else
  550                         lock_flags = LK_SHARED;
  551                 vn_lock(vp, lock_flags | LK_RETRY);
  552         } else
  553                 rl_cookie = NULL;
  554 
  555         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
  556 #ifdef MAC
  557         if ((ioflg & IO_NOMACCHECK) == 0) {
  558                 if (rw == UIO_READ)
  559                         error = mac_vnode_check_read(active_cred, file_cred,
  560                             vp);
  561                 else
  562                         error = mac_vnode_check_write(active_cred, file_cred,
  563                             vp);
  564         }
  565 #endif
  566         if (error == 0) {
  567                 if (file_cred != NULL)
  568                         cred = file_cred;
  569                 else
  570                         cred = active_cred;
  571                 if (do_vn_io_fault(vp, &auio)) {
  572                         args.kind = VN_IO_FAULT_VOP;
  573                         args.cred = cred;
  574                         args.flags = ioflg;
  575                         args.args.vop_args.vp = vp;
  576                         error = vn_io_fault1(vp, &auio, &args, td);
  577                 } else if (rw == UIO_READ) {
  578                         error = VOP_READ(vp, &auio, ioflg, cred);
  579                 } else /* if (rw == UIO_WRITE) */ {
  580                         error = VOP_WRITE(vp, &auio, ioflg, cred);
  581                 }
  582         }
  583         if (aresid)
  584                 *aresid = auio.uio_resid;
  585         else
  586                 if (auio.uio_resid && error == 0)
  587                         error = EIO;
  588         if ((ioflg & IO_NODELOCKED) == 0) {
  589                 VOP_UNLOCK(vp, 0);
  590                 if (mp != NULL)
  591                         vn_finished_write(mp);
  592         }
  593  out:
  594         if (rl_cookie != NULL)
  595                 vn_rangelock_unlock(vp, rl_cookie);
  596         return (error);
  597 }
  598 
  599 /*
  600  * Package up an I/O request on a vnode into a uio and do it.  The I/O
  601  * request is split up into smaller chunks and we try to avoid saturating
  602  * the buffer cache while potentially holding a vnode locked, so we 
  603  * check bwillwrite() before calling vn_rdwr().  We also call kern_yield()
  604  * to give other processes a chance to lock the vnode (either other processes
  605  * core'ing the same binary, or unrelated processes scanning the directory).
  606  */
  607 int
  608 vn_rdwr_inchunks(rw, vp, base, len, offset, segflg, ioflg, active_cred,
  609     file_cred, aresid, td)
  610         enum uio_rw rw;
  611         struct vnode *vp;
  612         void *base;
  613         size_t len;
  614         off_t offset;
  615         enum uio_seg segflg;
  616         int ioflg;
  617         struct ucred *active_cred;
  618         struct ucred *file_cred;
  619         size_t *aresid;
  620         struct thread *td;
  621 {
  622         int error = 0;
  623         ssize_t iaresid;
  624 
  625         do {
  626                 int chunk;
  627 
  628                 /*
  629                  * Force `offset' to a multiple of MAXBSIZE except possibly
  630                  * for the first chunk, so that filesystems only need to
  631                  * write full blocks except possibly for the first and last
  632                  * chunks.
  633                  */
  634                 chunk = MAXBSIZE - (uoff_t)offset % MAXBSIZE;
  635 
  636                 if (chunk > len)
  637                         chunk = len;
  638                 if (rw != UIO_READ && vp->v_type == VREG)
  639                         bwillwrite();
  640                 iaresid = 0;
  641                 error = vn_rdwr(rw, vp, base, chunk, offset, segflg,
  642                     ioflg, active_cred, file_cred, &iaresid, td);
  643                 len -= chunk;   /* aresid calc already includes length */
  644                 if (error)
  645                         break;
  646                 offset += chunk;
  647                 base = (char *)base + chunk;
  648                 kern_yield(PRI_USER);
  649         } while (len);
  650         if (aresid)
  651                 *aresid = len + iaresid;
  652         return (error);
  653 }
  654 
  655 off_t
  656 foffset_lock(struct file *fp, int flags)
  657 {
  658         struct mtx *mtxp;
  659         off_t res;
  660 
  661         KASSERT((flags & FOF_OFFSET) == 0, ("FOF_OFFSET passed"));
  662 
  663 #if OFF_MAX <= LONG_MAX
  664         /*
  665          * Caller only wants the current f_offset value.  Assume that
  666          * the long and shorter integer types reads are atomic.
  667          */
  668         if ((flags & FOF_NOLOCK) != 0)
  669                 return (fp->f_offset);
  670 #endif
  671 
  672         /*
  673          * According to McKusick the vn lock was protecting f_offset here.
  674          * It is now protected by the FOFFSET_LOCKED flag.
  675          */
  676         mtxp = mtx_pool_find(mtxpool_sleep, fp);
  677         mtx_lock(mtxp);
  678         if ((flags & FOF_NOLOCK) == 0) {
  679                 while (fp->f_vnread_flags & FOFFSET_LOCKED) {
  680                         fp->f_vnread_flags |= FOFFSET_LOCK_WAITING;
  681                         msleep(&fp->f_vnread_flags, mtxp, PUSER -1,
  682                             "vofflock", 0);
  683                 }
  684                 fp->f_vnread_flags |= FOFFSET_LOCKED;
  685         }
  686         res = fp->f_offset;
  687         mtx_unlock(mtxp);
  688         return (res);
  689 }
  690 
  691 void
  692 foffset_unlock(struct file *fp, off_t val, int flags)
  693 {
  694         struct mtx *mtxp;
  695 
  696         KASSERT((flags & FOF_OFFSET) == 0, ("FOF_OFFSET passed"));
  697 
  698 #if OFF_MAX <= LONG_MAX
  699         if ((flags & FOF_NOLOCK) != 0) {
  700                 if ((flags & FOF_NOUPDATE) == 0)
  701                         fp->f_offset = val;
  702                 if ((flags & FOF_NEXTOFF) != 0)
  703                         fp->f_nextoff = val;
  704                 return;
  705         }
  706 #endif
  707 
  708         mtxp = mtx_pool_find(mtxpool_sleep, fp);
  709         mtx_lock(mtxp);
  710         if ((flags & FOF_NOUPDATE) == 0)
  711                 fp->f_offset = val;
  712         if ((flags & FOF_NEXTOFF) != 0)
  713                 fp->f_nextoff = val;
  714         if ((flags & FOF_NOLOCK) == 0) {
  715                 KASSERT((fp->f_vnread_flags & FOFFSET_LOCKED) != 0,
  716                     ("Lost FOFFSET_LOCKED"));
  717                 if (fp->f_vnread_flags & FOFFSET_LOCK_WAITING)
  718                         wakeup(&fp->f_vnread_flags);
  719                 fp->f_vnread_flags = 0;
  720         }
  721         mtx_unlock(mtxp);
  722 }
  723 
  724 void
  725 foffset_lock_uio(struct file *fp, struct uio *uio, int flags)
  726 {
  727 
  728         if ((flags & FOF_OFFSET) == 0)
  729                 uio->uio_offset = foffset_lock(fp, flags);
  730 }
  731 
  732 void
  733 foffset_unlock_uio(struct file *fp, struct uio *uio, int flags)
  734 {
  735 
  736         if ((flags & FOF_OFFSET) == 0)
  737                 foffset_unlock(fp, uio->uio_offset, flags);
  738 }
  739 
  740 static int
  741 get_advice(struct file *fp, struct uio *uio)
  742 {
  743         struct mtx *mtxp;
  744         int ret;
  745 
  746         ret = POSIX_FADV_NORMAL;
  747         if (fp->f_advice == NULL || fp->f_vnode->v_type != VREG)
  748                 return (ret);
  749 
  750         mtxp = mtx_pool_find(mtxpool_sleep, fp);
  751         mtx_lock(mtxp);
  752         if (fp->f_advice != NULL &&
  753             uio->uio_offset >= fp->f_advice->fa_start &&
  754             uio->uio_offset + uio->uio_resid <= fp->f_advice->fa_end)
  755                 ret = fp->f_advice->fa_advice;
  756         mtx_unlock(mtxp);
  757         return (ret);
  758 }
  759 
  760 /*
  761  * File table vnode read routine.
  762  */
  763 static int
  764 vn_read(fp, uio, active_cred, flags, td)
  765         struct file *fp;
  766         struct uio *uio;
  767         struct ucred *active_cred;
  768         int flags;
  769         struct thread *td;
  770 {
  771         struct vnode *vp;
  772         off_t orig_offset;
  773         int error, ioflag;
  774         int advice;
  775 
  776         KASSERT(uio->uio_td == td, ("uio_td %p is not td %p",
  777             uio->uio_td, td));
  778         KASSERT(flags & FOF_OFFSET, ("No FOF_OFFSET"));
  779         vp = fp->f_vnode;
  780         ioflag = 0;
  781         if (fp->f_flag & FNONBLOCK)
  782                 ioflag |= IO_NDELAY;
  783         if (fp->f_flag & O_DIRECT)
  784                 ioflag |= IO_DIRECT;
  785         advice = get_advice(fp, uio);
  786         vn_lock(vp, LK_SHARED | LK_RETRY);
  787 
  788         switch (advice) {
  789         case POSIX_FADV_NORMAL:
  790         case POSIX_FADV_SEQUENTIAL:
  791         case POSIX_FADV_NOREUSE:
  792                 ioflag |= sequential_heuristic(uio, fp);
  793                 break;
  794         case POSIX_FADV_RANDOM:
  795                 /* Disable read-ahead for random I/O. */
  796                 break;
  797         }
  798         orig_offset = uio->uio_offset;
  799 
  800 #ifdef MAC
  801         error = mac_vnode_check_read(active_cred, fp->f_cred, vp);
  802         if (error == 0)
  803 #endif
  804                 error = VOP_READ(vp, uio, ioflag, fp->f_cred);
  805         fp->f_nextoff = uio->uio_offset;
  806         VOP_UNLOCK(vp, 0);
  807         if (error == 0 && advice == POSIX_FADV_NOREUSE &&
  808             orig_offset != uio->uio_offset)
  809                 /*
  810                  * Use POSIX_FADV_DONTNEED to flush pages and buffers
  811                  * for the backing file after a POSIX_FADV_NOREUSE
  812                  * read(2).
  813                  */
  814                 error = VOP_ADVISE(vp, orig_offset, uio->uio_offset - 1,
  815                     POSIX_FADV_DONTNEED);
  816         return (error);
  817 }
  818 
  819 /*
  820  * File table vnode write routine.
  821  */
  822 static int
  823 vn_write(fp, uio, active_cred, flags, td)
  824         struct file *fp;
  825         struct uio *uio;
  826         struct ucred *active_cred;
  827         int flags;
  828         struct thread *td;
  829 {
  830         struct vnode *vp;
  831         struct mount *mp;
  832         off_t orig_offset;
  833         int error, ioflag, lock_flags;
  834         int advice;
  835 
  836         KASSERT(uio->uio_td == td, ("uio_td %p is not td %p",
  837             uio->uio_td, td));
  838         KASSERT(flags & FOF_OFFSET, ("No FOF_OFFSET"));
  839         vp = fp->f_vnode;
  840         if (vp->v_type == VREG)
  841                 bwillwrite();
  842         ioflag = IO_UNIT;
  843         if (vp->v_type == VREG && (fp->f_flag & O_APPEND))
  844                 ioflag |= IO_APPEND;
  845         if (fp->f_flag & FNONBLOCK)
  846                 ioflag |= IO_NDELAY;
  847         if (fp->f_flag & O_DIRECT)
  848                 ioflag |= IO_DIRECT;
  849         if ((fp->f_flag & O_FSYNC) ||
  850             (vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS)))
  851                 ioflag |= IO_SYNC;
  852         mp = NULL;
  853         if (vp->v_type != VCHR &&
  854             (error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) != 0)
  855                 goto unlock;
  856 
  857         advice = get_advice(fp, uio);
  858 
  859         if (MNT_SHARED_WRITES(mp) ||
  860             (mp == NULL && MNT_SHARED_WRITES(vp->v_mount))) {
  861                 lock_flags = LK_SHARED;
  862         } else {
  863                 lock_flags = LK_EXCLUSIVE;
  864         }
  865 
  866         vn_lock(vp, lock_flags | LK_RETRY);
  867         switch (advice) {
  868         case POSIX_FADV_NORMAL:
  869         case POSIX_FADV_SEQUENTIAL:
  870         case POSIX_FADV_NOREUSE:
  871                 ioflag |= sequential_heuristic(uio, fp);
  872                 break;
  873         case POSIX_FADV_RANDOM:
  874                 /* XXX: Is this correct? */
  875                 break;
  876         }
  877         orig_offset = uio->uio_offset;
  878 
  879 #ifdef MAC
  880         error = mac_vnode_check_write(active_cred, fp->f_cred, vp);
  881         if (error == 0)
  882 #endif
  883                 error = VOP_WRITE(vp, uio, ioflag, fp->f_cred);
  884         fp->f_nextoff = uio->uio_offset;
  885         VOP_UNLOCK(vp, 0);
  886         if (vp->v_type != VCHR)
  887                 vn_finished_write(mp);
  888         if (error == 0 && advice == POSIX_FADV_NOREUSE &&
  889             orig_offset != uio->uio_offset)
  890                 /*
  891                  * Use POSIX_FADV_DONTNEED to flush pages and buffers
  892                  * for the backing file after a POSIX_FADV_NOREUSE
  893                  * write(2).
  894                  */
  895                 error = VOP_ADVISE(vp, orig_offset, uio->uio_offset - 1,
  896                     POSIX_FADV_DONTNEED);
  897 unlock:
  898         return (error);
  899 }
  900 
  901 /*
  902  * The vn_io_fault() is a wrapper around vn_read() and vn_write() to
  903  * prevent the following deadlock:
  904  *
  905  * Assume that the thread A reads from the vnode vp1 into userspace
  906  * buffer buf1 backed by the pages of vnode vp2.  If a page in buf1 is
  907  * currently not resident, then system ends up with the call chain
  908  *   vn_read() -> VOP_READ(vp1) -> uiomove() -> [Page Fault] ->
  909  *     vm_fault(buf1) -> vnode_pager_getpages(vp2) -> VOP_GETPAGES(vp2)
  910  * which establishes lock order vp1->vn_lock, then vp2->vn_lock.
  911  * If, at the same time, thread B reads from vnode vp2 into buffer buf2
  912  * backed by the pages of vnode vp1, and some page in buf2 is not
  913  * resident, we get a reversed order vp2->vn_lock, then vp1->vn_lock.
  914  *
  915  * To prevent the lock order reversal and deadlock, vn_io_fault() does
  916  * not allow page faults to happen during VOP_READ() or VOP_WRITE().
  917  * Instead, it first tries to do the whole range i/o with pagefaults
  918  * disabled. If all pages in the i/o buffer are resident and mapped,
  919  * VOP will succeed (ignoring the genuine filesystem errors).
  920  * Otherwise, we get back EFAULT, and vn_io_fault() falls back to do
  921  * i/o in chunks, with all pages in the chunk prefaulted and held
  922  * using vm_fault_quick_hold_pages().
  923  *
  924  * Filesystems using this deadlock avoidance scheme should use the
  925  * array of the held pages from uio, saved in the curthread->td_ma,
  926  * instead of doing uiomove().  A helper function
  927  * vn_io_fault_uiomove() converts uiomove request into
  928  * uiomove_fromphys() over td_ma array.
  929  *
  930  * Since vnode locks do not cover the whole i/o anymore, rangelocks
  931  * make the current i/o request atomic with respect to other i/os and
  932  * truncations.
  933  */
  934 
  935 /*
  936  * Decode vn_io_fault_args and perform the corresponding i/o.
  937  */
  938 static int
  939 vn_io_fault_doio(struct vn_io_fault_args *args, struct uio *uio,
  940     struct thread *td)
  941 {
  942 
  943         switch (args->kind) {
  944         case VN_IO_FAULT_FOP:
  945                 return ((args->args.fop_args.doio)(args->args.fop_args.fp,
  946                     uio, args->cred, args->flags, td));
  947         case VN_IO_FAULT_VOP:
  948                 if (uio->uio_rw == UIO_READ) {
  949                         return (VOP_READ(args->args.vop_args.vp, uio,
  950                             args->flags, args->cred));
  951                 } else if (uio->uio_rw == UIO_WRITE) {
  952                         return (VOP_WRITE(args->args.vop_args.vp, uio,
  953                             args->flags, args->cred));
  954                 }
  955                 break;
  956         }
  957         panic("vn_io_fault_doio: unknown kind of io %d %d", args->kind,
  958             uio->uio_rw);
  959 }
  960 
  961 static int
  962 vn_io_fault_touch(char *base, const struct uio *uio)
  963 {
  964         int r;
  965 
  966         r = fubyte(base);
  967         if (r == -1 || (uio->uio_rw == UIO_READ && subyte(base, r) == -1))
  968                 return (EFAULT);
  969         return (0);
  970 }
  971 
  972 static int
  973 vn_io_fault_prefault_user(const struct uio *uio)
  974 {
  975         char *base;
  976         const struct iovec *iov;
  977         size_t len;
  978         ssize_t resid;
  979         int error, i;
  980 
  981         KASSERT(uio->uio_segflg == UIO_USERSPACE,
  982             ("vn_io_fault_prefault userspace"));
  983 
  984         error = i = 0;
  985         iov = uio->uio_iov;
  986         resid = uio->uio_resid;
  987         base = iov->iov_base;
  988         len = iov->iov_len;
  989         while (resid > 0) {
  990                 error = vn_io_fault_touch(base, uio);
  991                 if (error != 0)
  992                         break;
  993                 if (len < PAGE_SIZE) {
  994                         if (len != 0) {
  995                                 error = vn_io_fault_touch(base + len - 1, uio);
  996                                 if (error != 0)
  997                                         break;
  998                                 resid -= len;
  999                         }
 1000                         if (++i >= uio->uio_iovcnt)
 1001                                 break;
 1002                         iov = uio->uio_iov + i;
 1003                         base = iov->iov_base;
 1004                         len = iov->iov_len;
 1005                 } else {
 1006                         len -= PAGE_SIZE;
 1007                         base += PAGE_SIZE;
 1008                         resid -= PAGE_SIZE;
 1009                 }
 1010         }
 1011         return (error);
 1012 }
 1013 
 1014 /*
 1015  * Common code for vn_io_fault(), agnostic to the kind of i/o request.
 1016  * Uses vn_io_fault_doio() to make the call to an actual i/o function.
 1017  * Used from vn_rdwr() and vn_io_fault(), which encode the i/o request
 1018  * into args and call vn_io_fault1() to handle faults during the user
 1019  * mode buffer accesses.
 1020  */
 1021 static int
 1022 vn_io_fault1(struct vnode *vp, struct uio *uio, struct vn_io_fault_args *args,
 1023     struct thread *td)
 1024 {
 1025         vm_page_t ma[io_hold_cnt + 2];
 1026         struct uio *uio_clone, short_uio;
 1027         struct iovec short_iovec[1];
 1028         vm_page_t *prev_td_ma;
 1029         vm_prot_t prot;
 1030         vm_offset_t addr, end;
 1031         size_t len, resid;
 1032         ssize_t adv;
 1033         int error, cnt, save, saveheld, prev_td_ma_cnt;
 1034 
 1035         if (vn_io_fault_prefault) {
 1036                 error = vn_io_fault_prefault_user(uio);
 1037                 if (error != 0)
 1038                         return (error); /* Or ignore ? */
 1039         }
 1040 
 1041         prot = uio->uio_rw == UIO_READ ? VM_PROT_WRITE : VM_PROT_READ;
 1042 
 1043         /*
 1044          * The UFS follows IO_UNIT directive and replays back both
 1045          * uio_offset and uio_resid if an error is encountered during the
 1046          * operation.  But, since the iovec may be already advanced,
 1047          * uio is still in an inconsistent state.
 1048          *
 1049          * Cache a copy of the original uio, which is advanced to the redo
 1050          * point using UIO_NOCOPY below.
 1051          */
 1052         uio_clone = cloneuio(uio);
 1053         resid = uio->uio_resid;
 1054 
 1055         short_uio.uio_segflg = UIO_USERSPACE;
 1056         short_uio.uio_rw = uio->uio_rw;
 1057         short_uio.uio_td = uio->uio_td;
 1058 
 1059         save = vm_fault_disable_pagefaults();
 1060         error = vn_io_fault_doio(args, uio, td);
 1061         if (error != EFAULT)
 1062                 goto out;
 1063 
 1064         atomic_add_long(&vn_io_faults_cnt, 1);
 1065         uio_clone->uio_segflg = UIO_NOCOPY;
 1066         uiomove(NULL, resid - uio->uio_resid, uio_clone);
 1067         uio_clone->uio_segflg = uio->uio_segflg;
 1068 
 1069         saveheld = curthread_pflags_set(TDP_UIOHELD);
 1070         prev_td_ma = td->td_ma;
 1071         prev_td_ma_cnt = td->td_ma_cnt;
 1072 
 1073         while (uio_clone->uio_resid != 0) {
 1074                 len = uio_clone->uio_iov->iov_len;
 1075                 if (len == 0) {
 1076                         KASSERT(uio_clone->uio_iovcnt >= 1,
 1077                             ("iovcnt underflow"));
 1078                         uio_clone->uio_iov++;
 1079                         uio_clone->uio_iovcnt--;
 1080                         continue;
 1081                 }
 1082                 if (len > io_hold_cnt * PAGE_SIZE)
 1083                         len = io_hold_cnt * PAGE_SIZE;
 1084                 addr = (uintptr_t)uio_clone->uio_iov->iov_base;
 1085                 end = round_page(addr + len);
 1086                 if (end < addr) {
 1087                         error = EFAULT;
 1088                         break;
 1089                 }
 1090                 cnt = atop(end - trunc_page(addr));
 1091                 /*
 1092                  * A perfectly misaligned address and length could cause
 1093                  * both the start and the end of the chunk to use partial
 1094                  * page.  +2 accounts for such a situation.
 1095                  */
 1096                 cnt = vm_fault_quick_hold_pages(&td->td_proc->p_vmspace->vm_map,
 1097                     addr, len, prot, ma, io_hold_cnt + 2);
 1098                 if (cnt == -1) {
 1099                         error = EFAULT;
 1100                         break;
 1101                 }
 1102                 short_uio.uio_iov = &short_iovec[0];
 1103                 short_iovec[0].iov_base = (void *)addr;
 1104                 short_uio.uio_iovcnt = 1;
 1105                 short_uio.uio_resid = short_iovec[0].iov_len = len;
 1106                 short_uio.uio_offset = uio_clone->uio_offset;
 1107                 td->td_ma = ma;
 1108                 td->td_ma_cnt = cnt;
 1109 
 1110                 error = vn_io_fault_doio(args, &short_uio, td);
 1111                 vm_page_unhold_pages(ma, cnt);
 1112                 adv = len - short_uio.uio_resid;
 1113 
 1114                 uio_clone->uio_iov->iov_base =
 1115                     (char *)uio_clone->uio_iov->iov_base + adv;
 1116                 uio_clone->uio_iov->iov_len -= adv;
 1117                 uio_clone->uio_resid -= adv;
 1118                 uio_clone->uio_offset += adv;
 1119 
 1120                 uio->uio_resid -= adv;
 1121                 uio->uio_offset += adv;
 1122 
 1123                 if (error != 0 || adv == 0)
 1124                         break;
 1125         }
 1126         td->td_ma = prev_td_ma;
 1127         td->td_ma_cnt = prev_td_ma_cnt;
 1128         curthread_pflags_restore(saveheld);
 1129 out:
 1130         vm_fault_enable_pagefaults(save);
 1131         free(uio_clone, M_IOV);
 1132         return (error);
 1133 }
 1134 
 1135 static int
 1136 vn_io_fault(struct file *fp, struct uio *uio, struct ucred *active_cred,
 1137     int flags, struct thread *td)
 1138 {
 1139         fo_rdwr_t *doio;
 1140         struct vnode *vp;
 1141         void *rl_cookie;
 1142         struct vn_io_fault_args args;
 1143         int error;
 1144 
 1145         doio = uio->uio_rw == UIO_READ ? vn_read : vn_write;
 1146         vp = fp->f_vnode;
 1147         foffset_lock_uio(fp, uio, flags);
 1148         if (do_vn_io_fault(vp, uio)) {
 1149                 args.kind = VN_IO_FAULT_FOP;
 1150                 args.args.fop_args.fp = fp;
 1151                 args.args.fop_args.doio = doio;
 1152                 args.cred = active_cred;
 1153                 args.flags = flags | FOF_OFFSET;
 1154                 if (uio->uio_rw == UIO_READ) {
 1155                         rl_cookie = vn_rangelock_rlock(vp, uio->uio_offset,
 1156                             uio->uio_offset + uio->uio_resid);
 1157                 } else if ((fp->f_flag & O_APPEND) != 0 ||
 1158                     (flags & FOF_OFFSET) == 0) {
 1159                         /* For appenders, punt and lock the whole range. */
 1160                         rl_cookie = vn_rangelock_wlock(vp, 0, OFF_MAX);
 1161                 } else {
 1162                         rl_cookie = vn_rangelock_wlock(vp, uio->uio_offset,
 1163                             uio->uio_offset + uio->uio_resid);
 1164                 }
 1165                 error = vn_io_fault1(vp, uio, &args, td);
 1166                 vn_rangelock_unlock(vp, rl_cookie);
 1167         } else {
 1168                 error = doio(fp, uio, active_cred, flags | FOF_OFFSET, td);
 1169         }
 1170         foffset_unlock_uio(fp, uio, flags);
 1171         return (error);
 1172 }
 1173 
 1174 /*
 1175  * Helper function to perform the requested uiomove operation using
 1176  * the held pages for io->uio_iov[0].iov_base buffer instead of
 1177  * copyin/copyout.  Access to the pages with uiomove_fromphys()
 1178  * instead of iov_base prevents page faults that could occur due to
 1179  * pmap_collect() invalidating the mapping created by
 1180  * vm_fault_quick_hold_pages(), or pageout daemon, page laundry or
 1181  * object cleanup revoking the write access from page mappings.
 1182  *
 1183  * Filesystems specified MNTK_NO_IOPF shall use vn_io_fault_uiomove()
 1184  * instead of plain uiomove().
 1185  */
 1186 int
 1187 vn_io_fault_uiomove(char *data, int xfersize, struct uio *uio)
 1188 {
 1189         struct uio transp_uio;
 1190         struct iovec transp_iov[1];
 1191         struct thread *td;
 1192         size_t adv;
 1193         int error, pgadv;
 1194 
 1195         td = curthread;
 1196         if ((td->td_pflags & TDP_UIOHELD) == 0 ||
 1197             uio->uio_segflg != UIO_USERSPACE)
 1198                 return (uiomove(data, xfersize, uio));
 1199 
 1200         KASSERT(uio->uio_iovcnt == 1, ("uio_iovcnt %d", uio->uio_iovcnt));
 1201         transp_iov[0].iov_base = data;
 1202         transp_uio.uio_iov = &transp_iov[0];
 1203         transp_uio.uio_iovcnt = 1;
 1204         if (xfersize > uio->uio_resid)
 1205                 xfersize = uio->uio_resid;
 1206         transp_uio.uio_resid = transp_iov[0].iov_len = xfersize;
 1207         transp_uio.uio_offset = 0;
 1208         transp_uio.uio_segflg = UIO_SYSSPACE;
 1209         /*
 1210          * Since transp_iov points to data, and td_ma page array
 1211          * corresponds to original uio->uio_iov, we need to invert the
 1212          * direction of the i/o operation as passed to
 1213          * uiomove_fromphys().
 1214          */
 1215         switch (uio->uio_rw) {
 1216         case UIO_WRITE:
 1217                 transp_uio.uio_rw = UIO_READ;
 1218                 break;
 1219         case UIO_READ:
 1220                 transp_uio.uio_rw = UIO_WRITE;
 1221                 break;
 1222         }
 1223         transp_uio.uio_td = uio->uio_td;
 1224         error = uiomove_fromphys(td->td_ma,
 1225             ((vm_offset_t)uio->uio_iov->iov_base) & PAGE_MASK,
 1226             xfersize, &transp_uio);
 1227         adv = xfersize - transp_uio.uio_resid;
 1228         pgadv =
 1229             (((vm_offset_t)uio->uio_iov->iov_base + adv) >> PAGE_SHIFT) -
 1230             (((vm_offset_t)uio->uio_iov->iov_base) >> PAGE_SHIFT);
 1231         td->td_ma += pgadv;
 1232         KASSERT(td->td_ma_cnt >= pgadv, ("consumed pages %d %d", td->td_ma_cnt,
 1233             pgadv));
 1234         td->td_ma_cnt -= pgadv;
 1235         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + adv;
 1236         uio->uio_iov->iov_len -= adv;
 1237         uio->uio_resid -= adv;
 1238         uio->uio_offset += adv;
 1239         return (error);
 1240 }
 1241 
 1242 int
 1243 vn_io_fault_pgmove(vm_page_t ma[], vm_offset_t offset, int xfersize,
 1244     struct uio *uio)
 1245 {
 1246         struct thread *td;
 1247         vm_offset_t iov_base;
 1248         int cnt, pgadv;
 1249 
 1250         td = curthread;
 1251         if ((td->td_pflags & TDP_UIOHELD) == 0 ||
 1252             uio->uio_segflg != UIO_USERSPACE)
 1253                 return (uiomove_fromphys(ma, offset, xfersize, uio));
 1254 
 1255         KASSERT(uio->uio_iovcnt == 1, ("uio_iovcnt %d", uio->uio_iovcnt));
 1256         cnt = xfersize > uio->uio_resid ? uio->uio_resid : xfersize;
 1257         iov_base = (vm_offset_t)uio->uio_iov->iov_base;
 1258         switch (uio->uio_rw) {
 1259         case UIO_WRITE:
 1260                 pmap_copy_pages(td->td_ma, iov_base & PAGE_MASK, ma,
 1261                     offset, cnt);
 1262                 break;
 1263         case UIO_READ:
 1264                 pmap_copy_pages(ma, offset, td->td_ma, iov_base & PAGE_MASK,
 1265                     cnt);
 1266                 break;
 1267         }
 1268         pgadv = ((iov_base + cnt) >> PAGE_SHIFT) - (iov_base >> PAGE_SHIFT);
 1269         td->td_ma += pgadv;
 1270         KASSERT(td->td_ma_cnt >= pgadv, ("consumed pages %d %d", td->td_ma_cnt,
 1271             pgadv));
 1272         td->td_ma_cnt -= pgadv;
 1273         uio->uio_iov->iov_base = (char *)(iov_base + cnt);
 1274         uio->uio_iov->iov_len -= cnt;
 1275         uio->uio_resid -= cnt;
 1276         uio->uio_offset += cnt;
 1277         return (0);
 1278 }
 1279 
 1280 
 1281 /*
 1282  * File table truncate routine.
 1283  */
 1284 static int
 1285 vn_truncate(struct file *fp, off_t length, struct ucred *active_cred,
 1286     struct thread *td)
 1287 {
 1288         struct vattr vattr;
 1289         struct mount *mp;
 1290         struct vnode *vp;
 1291         void *rl_cookie;
 1292         int error;
 1293 
 1294         vp = fp->f_vnode;
 1295 
 1296         /*
 1297          * Lock the whole range for truncation.  Otherwise split i/o
 1298          * might happen partly before and partly after the truncation.
 1299          */
 1300         rl_cookie = vn_rangelock_wlock(vp, 0, OFF_MAX);
 1301         error = vn_start_write(vp, &mp, V_WAIT | PCATCH);
 1302         if (error)
 1303                 goto out1;
 1304         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 1305         if (vp->v_type == VDIR) {
 1306                 error = EISDIR;
 1307                 goto out;
 1308         }
 1309 #ifdef MAC
 1310         error = mac_vnode_check_write(active_cred, fp->f_cred, vp);
 1311         if (error)
 1312                 goto out;
 1313 #endif
 1314         error = vn_writechk(vp);
 1315         if (error == 0) {
 1316                 VATTR_NULL(&vattr);
 1317                 vattr.va_size = length;
 1318                 if ((fp->f_flag & O_FSYNC) != 0)
 1319                         vattr.va_vaflags |= VA_SYNC;
 1320                 error = VOP_SETATTR(vp, &vattr, fp->f_cred);
 1321         }
 1322 out:
 1323         VOP_UNLOCK(vp, 0);
 1324         vn_finished_write(mp);
 1325 out1:
 1326         vn_rangelock_unlock(vp, rl_cookie);
 1327         return (error);
 1328 }
 1329 
 1330 /*
 1331  * File table vnode stat routine.
 1332  */
 1333 static int
 1334 vn_statfile(fp, sb, active_cred, td)
 1335         struct file *fp;
 1336         struct stat *sb;
 1337         struct ucred *active_cred;
 1338         struct thread *td;
 1339 {
 1340         struct vnode *vp = fp->f_vnode;
 1341         int error;
 1342 
 1343         vn_lock(vp, LK_SHARED | LK_RETRY);
 1344         error = vn_stat(vp, sb, active_cred, fp->f_cred, td);
 1345         VOP_UNLOCK(vp, 0);
 1346 
 1347         return (error);
 1348 }
 1349 
 1350 /*
 1351  * Stat a vnode; implementation for the stat syscall
 1352  */
 1353 int
 1354 vn_stat(vp, sb, active_cred, file_cred, td)
 1355         struct vnode *vp;
 1356         register struct stat *sb;
 1357         struct ucred *active_cred;
 1358         struct ucred *file_cred;
 1359         struct thread *td;
 1360 {
 1361         struct vattr vattr;
 1362         register struct vattr *vap;
 1363         int error;
 1364         u_short mode;
 1365 
 1366         AUDIT_ARG_VNODE1(vp);
 1367 #ifdef MAC
 1368         error = mac_vnode_check_stat(active_cred, file_cred, vp);
 1369         if (error)
 1370                 return (error);
 1371 #endif
 1372 
 1373         vap = &vattr;
 1374 
 1375         /*
 1376          * Initialize defaults for new and unusual fields, so that file
 1377          * systems which don't support these fields don't need to know
 1378          * about them.
 1379          */
 1380         vap->va_birthtime.tv_sec = -1;
 1381         vap->va_birthtime.tv_nsec = 0;
 1382         vap->va_fsid = VNOVAL;
 1383         vap->va_rdev = NODEV;
 1384 
 1385         error = VOP_GETATTR(vp, vap, active_cred);
 1386         if (error)
 1387                 return (error);
 1388 
 1389         /*
 1390          * Zero the spare stat fields
 1391          */
 1392         bzero(sb, sizeof *sb);
 1393 
 1394         /*
 1395          * Copy from vattr table
 1396          */
 1397         if (vap->va_fsid != VNOVAL)
 1398                 sb->st_dev = vap->va_fsid;
 1399         else
 1400                 sb->st_dev = vp->v_mount->mnt_stat.f_fsid.val[0];
 1401         sb->st_ino = vap->va_fileid;
 1402         mode = vap->va_mode;
 1403         switch (vap->va_type) {
 1404         case VREG:
 1405                 mode |= S_IFREG;
 1406                 break;
 1407         case VDIR:
 1408                 mode |= S_IFDIR;
 1409                 break;
 1410         case VBLK:
 1411                 mode |= S_IFBLK;
 1412                 break;
 1413         case VCHR:
 1414                 mode |= S_IFCHR;
 1415                 break;
 1416         case VLNK:
 1417                 mode |= S_IFLNK;
 1418                 break;
 1419         case VSOCK:
 1420                 mode |= S_IFSOCK;
 1421                 break;
 1422         case VFIFO:
 1423                 mode |= S_IFIFO;
 1424                 break;
 1425         default:
 1426                 return (EBADF);
 1427         }
 1428         sb->st_mode = mode;
 1429         sb->st_nlink = vap->va_nlink;
 1430         sb->st_uid = vap->va_uid;
 1431         sb->st_gid = vap->va_gid;
 1432         sb->st_rdev = vap->va_rdev;
 1433         if (vap->va_size > OFF_MAX)
 1434                 return (EOVERFLOW);
 1435         sb->st_size = vap->va_size;
 1436         sb->st_atim = vap->va_atime;
 1437         sb->st_mtim = vap->va_mtime;
 1438         sb->st_ctim = vap->va_ctime;
 1439         sb->st_birthtim = vap->va_birthtime;
 1440 
 1441         /*
 1442          * According to www.opengroup.org, the meaning of st_blksize is 
 1443          *   "a filesystem-specific preferred I/O block size for this 
 1444          *    object.  In some filesystem types, this may vary from file
 1445          *    to file"
 1446          * Use miminum/default of PAGE_SIZE (e.g. for VCHR).
 1447          */
 1448 
 1449         sb->st_blksize = max(PAGE_SIZE, vap->va_blocksize);
 1450         
 1451         sb->st_flags = vap->va_flags;
 1452         if (priv_check(td, PRIV_VFS_GENERATION))
 1453                 sb->st_gen = 0;
 1454         else
 1455                 sb->st_gen = vap->va_gen;
 1456 
 1457         sb->st_blocks = vap->va_bytes / S_BLKSIZE;
 1458         return (0);
 1459 }
 1460 
 1461 /*
 1462  * File table vnode ioctl routine.
 1463  */
 1464 static int
 1465 vn_ioctl(fp, com, data, active_cred, td)
 1466         struct file *fp;
 1467         u_long com;
 1468         void *data;
 1469         struct ucred *active_cred;
 1470         struct thread *td;
 1471 {
 1472         struct vattr vattr;
 1473         struct vnode *vp;
 1474         int error;
 1475 
 1476         vp = fp->f_vnode;
 1477         switch (vp->v_type) {
 1478         case VDIR:
 1479         case VREG:
 1480                 switch (com) {
 1481                 case FIONREAD:
 1482                         vn_lock(vp, LK_SHARED | LK_RETRY);
 1483                         error = VOP_GETATTR(vp, &vattr, active_cred);
 1484                         VOP_UNLOCK(vp, 0);
 1485                         if (error == 0)
 1486                                 *(int *)data = vattr.va_size - fp->f_offset;
 1487                         return (error);
 1488                 case FIONBIO:
 1489                 case FIOASYNC:
 1490                         return (0);
 1491                 default:
 1492                         return (VOP_IOCTL(vp, com, data, fp->f_flag,
 1493                             active_cred, td));
 1494                 }
 1495         default:
 1496                 return (ENOTTY);
 1497         }
 1498 }
 1499 
 1500 /*
 1501  * File table vnode poll routine.
 1502  */
 1503 static int
 1504 vn_poll(fp, events, active_cred, td)
 1505         struct file *fp;
 1506         int events;
 1507         struct ucred *active_cred;
 1508         struct thread *td;
 1509 {
 1510         struct vnode *vp;
 1511         int error;
 1512 
 1513         vp = fp->f_vnode;
 1514 #ifdef MAC
 1515         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 1516         AUDIT_ARG_VNODE1(vp);
 1517         error = mac_vnode_check_poll(active_cred, fp->f_cred, vp);
 1518         VOP_UNLOCK(vp, 0);
 1519         if (!error)
 1520 #endif
 1521 
 1522         error = VOP_POLL(vp, events, fp->f_cred, td);
 1523         return (error);
 1524 }
 1525 
 1526 /*
 1527  * Acquire the requested lock and then check for validity.  LK_RETRY
 1528  * permits vn_lock to return doomed vnodes.
 1529  */
 1530 int
 1531 _vn_lock(struct vnode *vp, int flags, char *file, int line)
 1532 {
 1533         int error;
 1534 
 1535         VNASSERT((flags & LK_TYPE_MASK) != 0, vp,
 1536             ("vn_lock called with no locktype."));
 1537         do {
 1538 #ifdef DEBUG_VFS_LOCKS
 1539                 KASSERT(vp->v_holdcnt != 0,
 1540                     ("vn_lock %p: zero hold count", vp));
 1541 #endif
 1542                 error = VOP_LOCK1(vp, flags, file, line);
 1543                 flags &= ~LK_INTERLOCK; /* Interlock is always dropped. */
 1544                 KASSERT((flags & LK_RETRY) == 0 || error == 0,
 1545                     ("LK_RETRY set with incompatible flags (0x%x) or an error occurred (%d)",
 1546                     flags, error));
 1547                 /*
 1548                  * Callers specify LK_RETRY if they wish to get dead vnodes.
 1549                  * If RETRY is not set, we return ENOENT instead.
 1550                  */
 1551                 if (error == 0 && vp->v_iflag & VI_DOOMED &&
 1552                     (flags & LK_RETRY) == 0) {
 1553                         VOP_UNLOCK(vp, 0);
 1554                         error = ENOENT;
 1555                         break;
 1556                 }
 1557         } while (flags & LK_RETRY && error != 0);
 1558         return (error);
 1559 }
 1560 
 1561 /*
 1562  * File table vnode close routine.
 1563  */
 1564 static int
 1565 vn_closefile(fp, td)
 1566         struct file *fp;
 1567         struct thread *td;
 1568 {
 1569         struct vnode *vp;
 1570         struct flock lf;
 1571         int error;
 1572 
 1573         vp = fp->f_vnode;
 1574         fp->f_ops = &badfileops;
 1575 
 1576         if (fp->f_type == DTYPE_VNODE && fp->f_flag & FHASLOCK)
 1577                 vref(vp);
 1578 
 1579         error = vn_close(vp, fp->f_flag, fp->f_cred, td);
 1580 
 1581         if (fp->f_type == DTYPE_VNODE && fp->f_flag & FHASLOCK) {
 1582                 lf.l_whence = SEEK_SET;
 1583                 lf.l_start = 0;
 1584                 lf.l_len = 0;
 1585                 lf.l_type = F_UNLCK;
 1586                 (void) VOP_ADVLOCK(vp, fp, F_UNLCK, &lf, F_FLOCK);
 1587                 vrele(vp);
 1588         }
 1589         return (error);
 1590 }
 1591 
 1592 static bool
 1593 vn_suspendable(struct mount *mp)
 1594 {
 1595 
 1596         return (mp->mnt_op->vfs_susp_clean != NULL);
 1597 }
 1598 
 1599 /*
 1600  * Preparing to start a filesystem write operation. If the operation is
 1601  * permitted, then we bump the count of operations in progress and
 1602  * proceed. If a suspend request is in progress, we wait until the
 1603  * suspension is over, and then proceed.
 1604  */
 1605 static int
 1606 vn_start_write_locked(struct mount *mp, int flags)
 1607 {
 1608         int error, mflags;
 1609 
 1610         mtx_assert(MNT_MTX(mp), MA_OWNED);
 1611         error = 0;
 1612 
 1613         /*
 1614          * Check on status of suspension.
 1615          */
 1616         if ((curthread->td_pflags & TDP_IGNSUSP) == 0 ||
 1617             mp->mnt_susp_owner != curthread) {
 1618                 mflags = ((mp->mnt_vfc->vfc_flags & VFCF_SBDRY) != 0 ?
 1619                     (flags & PCATCH) : 0) | (PUSER - 1);
 1620                 while ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0) {
 1621                         if (flags & V_NOWAIT) {
 1622                                 error = EWOULDBLOCK;
 1623                                 goto unlock;
 1624                         }
 1625                         error = msleep(&mp->mnt_flag, MNT_MTX(mp), mflags,
 1626                             "suspfs", 0);
 1627                         if (error)
 1628                                 goto unlock;
 1629                 }
 1630         }
 1631         if (flags & V_XSLEEP)
 1632                 goto unlock;
 1633         mp->mnt_writeopcount++;
 1634 unlock:
 1635         if (error != 0 || (flags & V_XSLEEP) != 0)
 1636                 MNT_REL(mp);
 1637         MNT_IUNLOCK(mp);
 1638         return (error);
 1639 }
 1640 
 1641 int
 1642 vn_start_write(struct vnode *vp, struct mount **mpp, int flags)
 1643 {
 1644         struct mount *mp;
 1645         int error;
 1646 
 1647         KASSERT((flags & V_MNTREF) == 0 || (*mpp != NULL && vp == NULL),
 1648             ("V_MNTREF requires mp"));
 1649 
 1650         error = 0;
 1651         /*
 1652          * If a vnode is provided, get and return the mount point that
 1653          * to which it will write.
 1654          */
 1655         if (vp != NULL) {
 1656                 if ((error = VOP_GETWRITEMOUNT(vp, mpp)) != 0) {
 1657                         *mpp = NULL;
 1658                         if (error != EOPNOTSUPP)
 1659                                 return (error);
 1660                         return (0);
 1661                 }
 1662         }
 1663         if ((mp = *mpp) == NULL)
 1664                 return (0);
 1665 
 1666         if (!vn_suspendable(mp)) {
 1667                 if (vp != NULL || (flags & V_MNTREF) != 0)
 1668                         vfs_rel(mp);
 1669                 return (0);
 1670         }
 1671 
 1672         /*
 1673          * VOP_GETWRITEMOUNT() returns with the mp refcount held through
 1674          * a vfs_ref().
 1675          * As long as a vnode is not provided we need to acquire a
 1676          * refcount for the provided mountpoint too, in order to
 1677          * emulate a vfs_ref().
 1678          */
 1679         MNT_ILOCK(mp);
 1680         if (vp == NULL && (flags & V_MNTREF) == 0)
 1681                 MNT_REF(mp);
 1682 
 1683         return (vn_start_write_locked(mp, flags));
 1684 }
 1685 
 1686 /*
 1687  * Secondary suspension. Used by operations such as vop_inactive
 1688  * routines that are needed by the higher level functions. These
 1689  * are allowed to proceed until all the higher level functions have
 1690  * completed (indicated by mnt_writeopcount dropping to zero). At that
 1691  * time, these operations are halted until the suspension is over.
 1692  */
 1693 int
 1694 vn_start_secondary_write(struct vnode *vp, struct mount **mpp, int flags)
 1695 {
 1696         struct mount *mp;
 1697         int error;
 1698 
 1699         KASSERT((flags & V_MNTREF) == 0 || (*mpp != NULL && vp == NULL),
 1700             ("V_MNTREF requires mp"));
 1701 
 1702  retry:
 1703         if (vp != NULL) {
 1704                 if ((error = VOP_GETWRITEMOUNT(vp, mpp)) != 0) {
 1705                         *mpp = NULL;
 1706                         if (error != EOPNOTSUPP)
 1707                                 return (error);
 1708                         return (0);
 1709                 }
 1710         }
 1711         /*
 1712          * If we are not suspended or have not yet reached suspended
 1713          * mode, then let the operation proceed.
 1714          */
 1715         if ((mp = *mpp) == NULL)
 1716                 return (0);
 1717 
 1718         if (!vn_suspendable(mp)) {
 1719                 if (vp != NULL || (flags & V_MNTREF) != 0)
 1720                         vfs_rel(mp);
 1721                 return (0);
 1722         }
 1723 
 1724         /*
 1725          * VOP_GETWRITEMOUNT() returns with the mp refcount held through
 1726          * a vfs_ref().
 1727          * As long as a vnode is not provided we need to acquire a
 1728          * refcount for the provided mountpoint too, in order to
 1729          * emulate a vfs_ref().
 1730          */
 1731         MNT_ILOCK(mp);
 1732         if (vp == NULL && (flags & V_MNTREF) == 0)
 1733                 MNT_REF(mp);
 1734         if ((mp->mnt_kern_flag & (MNTK_SUSPENDED | MNTK_SUSPEND2)) == 0) {
 1735                 mp->mnt_secondary_writes++;
 1736                 mp->mnt_secondary_accwrites++;
 1737                 MNT_IUNLOCK(mp);
 1738                 return (0);
 1739         }
 1740         if (flags & V_NOWAIT) {
 1741                 MNT_REL(mp);
 1742                 MNT_IUNLOCK(mp);
 1743                 return (EWOULDBLOCK);
 1744         }
 1745         /*
 1746          * Wait for the suspension to finish.
 1747          */
 1748         error = msleep(&mp->mnt_flag, MNT_MTX(mp), (PUSER - 1) | PDROP |
 1749             ((mp->mnt_vfc->vfc_flags & VFCF_SBDRY) != 0 ? (flags & PCATCH) : 0),
 1750             "suspfs", 0);
 1751         vfs_rel(mp);
 1752         if (error == 0)
 1753                 goto retry;
 1754         return (error);
 1755 }
 1756 
 1757 /*
 1758  * Filesystem write operation has completed. If we are suspending and this
 1759  * operation is the last one, notify the suspender that the suspension is
 1760  * now in effect.
 1761  */
 1762 void
 1763 vn_finished_write(mp)
 1764         struct mount *mp;
 1765 {
 1766         if (mp == NULL || !vn_suspendable(mp))
 1767                 return;
 1768         MNT_ILOCK(mp);
 1769         MNT_REL(mp);
 1770         mp->mnt_writeopcount--;
 1771         if (mp->mnt_writeopcount < 0)
 1772                 panic("vn_finished_write: neg cnt");
 1773         if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0 &&
 1774             mp->mnt_writeopcount <= 0)
 1775                 wakeup(&mp->mnt_writeopcount);
 1776         MNT_IUNLOCK(mp);
 1777 }
 1778 
 1779 
 1780 /*
 1781  * Filesystem secondary write operation has completed. If we are
 1782  * suspending and this operation is the last one, notify the suspender
 1783  * that the suspension is now in effect.
 1784  */
 1785 void
 1786 vn_finished_secondary_write(mp)
 1787         struct mount *mp;
 1788 {
 1789         if (mp == NULL || !vn_suspendable(mp))
 1790                 return;
 1791         MNT_ILOCK(mp);
 1792         MNT_REL(mp);
 1793         mp->mnt_secondary_writes--;
 1794         if (mp->mnt_secondary_writes < 0)
 1795                 panic("vn_finished_secondary_write: neg cnt");
 1796         if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0 &&
 1797             mp->mnt_secondary_writes <= 0)
 1798                 wakeup(&mp->mnt_secondary_writes);
 1799         MNT_IUNLOCK(mp);
 1800 }
 1801 
 1802 
 1803 
 1804 /*
 1805  * Request a filesystem to suspend write operations.
 1806  */
 1807 int
 1808 vfs_write_suspend(struct mount *mp, int flags)
 1809 {
 1810         int error;
 1811 
 1812         MPASS(vn_suspendable(mp));
 1813 
 1814         MNT_ILOCK(mp);
 1815         if (mp->mnt_susp_owner == curthread) {
 1816                 MNT_IUNLOCK(mp);
 1817                 return (EALREADY);
 1818         }
 1819         while (mp->mnt_kern_flag & MNTK_SUSPEND)
 1820                 msleep(&mp->mnt_flag, MNT_MTX(mp), PUSER - 1, "wsuspfs", 0);
 1821 
 1822         /*
 1823          * Unmount holds a write reference on the mount point.  If we
 1824          * own busy reference and drain for writers, we deadlock with
 1825          * the reference draining in the unmount path.  Callers of
 1826          * vfs_write_suspend() must specify VS_SKIP_UNMOUNT if
 1827          * vfs_busy() reference is owned and caller is not in the
 1828          * unmount context.
 1829          */
 1830         if ((flags & VS_SKIP_UNMOUNT) != 0 &&
 1831             (mp->mnt_kern_flag & MNTK_UNMOUNT) != 0) {
 1832                 MNT_IUNLOCK(mp);
 1833                 return (EBUSY);
 1834         }
 1835 
 1836         mp->mnt_kern_flag |= MNTK_SUSPEND;
 1837         mp->mnt_susp_owner = curthread;
 1838         if (mp->mnt_writeopcount > 0)
 1839                 (void) msleep(&mp->mnt_writeopcount, 
 1840                     MNT_MTX(mp), (PUSER - 1)|PDROP, "suspwt", 0);
 1841         else
 1842                 MNT_IUNLOCK(mp);
 1843         if ((error = VFS_SYNC(mp, MNT_SUSPEND)) != 0)
 1844                 vfs_write_resume(mp, 0);
 1845         return (error);
 1846 }
 1847 
 1848 /*
 1849  * Request a filesystem to resume write operations.
 1850  */
 1851 void
 1852 vfs_write_resume(struct mount *mp, int flags)
 1853 {
 1854 
 1855         MPASS(vn_suspendable(mp));
 1856 
 1857         MNT_ILOCK(mp);
 1858         if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0) {
 1859                 KASSERT(mp->mnt_susp_owner == curthread, ("mnt_susp_owner"));
 1860                 mp->mnt_kern_flag &= ~(MNTK_SUSPEND | MNTK_SUSPEND2 |
 1861                                        MNTK_SUSPENDED);
 1862                 mp->mnt_susp_owner = NULL;
 1863                 wakeup(&mp->mnt_writeopcount);
 1864                 wakeup(&mp->mnt_flag);
 1865                 curthread->td_pflags &= ~TDP_IGNSUSP;
 1866                 if ((flags & VR_START_WRITE) != 0) {
 1867                         MNT_REF(mp);
 1868                         mp->mnt_writeopcount++;
 1869                 }
 1870                 MNT_IUNLOCK(mp);
 1871                 if ((flags & VR_NO_SUSPCLR) == 0)
 1872                         VFS_SUSP_CLEAN(mp);
 1873         } else if ((flags & VR_START_WRITE) != 0) {
 1874                 MNT_REF(mp);
 1875                 vn_start_write_locked(mp, 0);
 1876         } else {
 1877                 MNT_IUNLOCK(mp);
 1878         }
 1879 }
 1880 
 1881 /*
 1882  * Helper loop around vfs_write_suspend() for filesystem unmount VFS
 1883  * methods.
 1884  */
 1885 int
 1886 vfs_write_suspend_umnt(struct mount *mp)
 1887 {
 1888         int error;
 1889 
 1890         MPASS(vn_suspendable(mp));
 1891         KASSERT((curthread->td_pflags & TDP_IGNSUSP) == 0,
 1892             ("vfs_write_suspend_umnt: recursed"));
 1893 
 1894         /* dounmount() already called vn_start_write(). */
 1895         for (;;) {
 1896                 vn_finished_write(mp);
 1897                 error = vfs_write_suspend(mp, 0);
 1898                 if (error != 0) {
 1899                         vn_start_write(NULL, &mp, V_WAIT);
 1900                         return (error);
 1901                 }
 1902                 MNT_ILOCK(mp);
 1903                 if ((mp->mnt_kern_flag & MNTK_SUSPENDED) != 0)
 1904                         break;
 1905                 MNT_IUNLOCK(mp);
 1906                 vn_start_write(NULL, &mp, V_WAIT);
 1907         }
 1908         mp->mnt_kern_flag &= ~(MNTK_SUSPENDED | MNTK_SUSPEND2);
 1909         wakeup(&mp->mnt_flag);
 1910         MNT_IUNLOCK(mp);
 1911         curthread->td_pflags |= TDP_IGNSUSP;
 1912         return (0);
 1913 }
 1914 
 1915 /*
 1916  * Implement kqueues for files by translating it to vnode operation.
 1917  */
 1918 static int
 1919 vn_kqfilter(struct file *fp, struct knote *kn)
 1920 {
 1921 
 1922         return (VOP_KQFILTER(fp->f_vnode, kn));
 1923 }
 1924 
 1925 /*
 1926  * Simplified in-kernel wrapper calls for extended attribute access.
 1927  * Both calls pass in a NULL credential, authorizing as "kernel" access.
 1928  * Set IO_NODELOCKED in ioflg if the vnode is already locked.
 1929  */
 1930 int
 1931 vn_extattr_get(struct vnode *vp, int ioflg, int attrnamespace,
 1932     const char *attrname, int *buflen, char *buf, struct thread *td)
 1933 {
 1934         struct uio      auio;
 1935         struct iovec    iov;
 1936         int     error;
 1937 
 1938         iov.iov_len = *buflen;
 1939         iov.iov_base = buf;
 1940 
 1941         auio.uio_iov = &iov;
 1942         auio.uio_iovcnt = 1;
 1943         auio.uio_rw = UIO_READ;
 1944         auio.uio_segflg = UIO_SYSSPACE;
 1945         auio.uio_td = td;
 1946         auio.uio_offset = 0;
 1947         auio.uio_resid = *buflen;
 1948 
 1949         if ((ioflg & IO_NODELOCKED) == 0)
 1950                 vn_lock(vp, LK_SHARED | LK_RETRY);
 1951 
 1952         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
 1953 
 1954         /* authorize attribute retrieval as kernel */
 1955         error = VOP_GETEXTATTR(vp, attrnamespace, attrname, &auio, NULL, NULL,
 1956             td);
 1957 
 1958         if ((ioflg & IO_NODELOCKED) == 0)
 1959                 VOP_UNLOCK(vp, 0);
 1960 
 1961         if (error == 0) {
 1962                 *buflen = *buflen - auio.uio_resid;
 1963         }
 1964 
 1965         return (error);
 1966 }
 1967 
 1968 /*
 1969  * XXX failure mode if partially written?
 1970  */
 1971 int
 1972 vn_extattr_set(struct vnode *vp, int ioflg, int attrnamespace,
 1973     const char *attrname, int buflen, char *buf, struct thread *td)
 1974 {
 1975         struct uio      auio;
 1976         struct iovec    iov;
 1977         struct mount    *mp;
 1978         int     error;
 1979 
 1980         iov.iov_len = buflen;
 1981         iov.iov_base = buf;
 1982 
 1983         auio.uio_iov = &iov;
 1984         auio.uio_iovcnt = 1;
 1985         auio.uio_rw = UIO_WRITE;
 1986         auio.uio_segflg = UIO_SYSSPACE;
 1987         auio.uio_td = td;
 1988         auio.uio_offset = 0;
 1989         auio.uio_resid = buflen;
 1990 
 1991         if ((ioflg & IO_NODELOCKED) == 0) {
 1992                 if ((error = vn_start_write(vp, &mp, V_WAIT)) != 0)
 1993                         return (error);
 1994                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 1995         }
 1996 
 1997         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
 1998 
 1999         /* authorize attribute setting as kernel */
 2000         error = VOP_SETEXTATTR(vp, attrnamespace, attrname, &auio, NULL, td);
 2001 
 2002         if ((ioflg & IO_NODELOCKED) == 0) {
 2003                 vn_finished_write(mp);
 2004                 VOP_UNLOCK(vp, 0);
 2005         }
 2006 
 2007         return (error);
 2008 }
 2009 
 2010 int
 2011 vn_extattr_rm(struct vnode *vp, int ioflg, int attrnamespace,
 2012     const char *attrname, struct thread *td)
 2013 {
 2014         struct mount    *mp;
 2015         int     error;
 2016 
 2017         if ((ioflg & IO_NODELOCKED) == 0) {
 2018                 if ((error = vn_start_write(vp, &mp, V_WAIT)) != 0)
 2019                         return (error);
 2020                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 2021         }
 2022 
 2023         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
 2024 
 2025         /* authorize attribute removal as kernel */
 2026         error = VOP_DELETEEXTATTR(vp, attrnamespace, attrname, NULL, td);
 2027         if (error == EOPNOTSUPP)
 2028                 error = VOP_SETEXTATTR(vp, attrnamespace, attrname, NULL,
 2029                     NULL, td);
 2030 
 2031         if ((ioflg & IO_NODELOCKED) == 0) {
 2032                 vn_finished_write(mp);
 2033                 VOP_UNLOCK(vp, 0);
 2034         }
 2035 
 2036         return (error);
 2037 }
 2038 
 2039 static int
 2040 vn_get_ino_alloc_vget(struct mount *mp, void *arg, int lkflags,
 2041     struct vnode **rvp)
 2042 {
 2043 
 2044         return (VFS_VGET(mp, *(ino_t *)arg, lkflags, rvp));
 2045 }
 2046 
 2047 int
 2048 vn_vget_ino(struct vnode *vp, ino_t ino, int lkflags, struct vnode **rvp)
 2049 {
 2050 
 2051         return (vn_vget_ino_gen(vp, vn_get_ino_alloc_vget, &ino,
 2052             lkflags, rvp));
 2053 }
 2054 
 2055 int
 2056 vn_vget_ino_gen(struct vnode *vp, vn_get_ino_t alloc, void *alloc_arg,
 2057     int lkflags, struct vnode **rvp)
 2058 {
 2059         struct mount *mp;
 2060         int ltype, error;
 2061 
 2062         ASSERT_VOP_LOCKED(vp, "vn_vget_ino_get");
 2063         mp = vp->v_mount;
 2064         ltype = VOP_ISLOCKED(vp);
 2065         KASSERT(ltype == LK_EXCLUSIVE || ltype == LK_SHARED,
 2066             ("vn_vget_ino: vp not locked"));
 2067         error = vfs_busy(mp, MBF_NOWAIT);
 2068         if (error != 0) {
 2069                 vfs_ref(mp);
 2070                 VOP_UNLOCK(vp, 0);
 2071                 error = vfs_busy(mp, 0);
 2072                 vn_lock(vp, ltype | LK_RETRY);
 2073                 vfs_rel(mp);
 2074                 if (error != 0)
 2075                         return (ENOENT);
 2076                 if (vp->v_iflag & VI_DOOMED) {
 2077                         vfs_unbusy(mp);
 2078                         return (ENOENT);
 2079                 }
 2080         }
 2081         VOP_UNLOCK(vp, 0);
 2082         error = alloc(mp, alloc_arg, lkflags, rvp);
 2083         vfs_unbusy(mp);
 2084         if (*rvp != vp)
 2085                 vn_lock(vp, ltype | LK_RETRY);
 2086         if (vp->v_iflag & VI_DOOMED) {
 2087                 if (error == 0) {
 2088                         if (*rvp == vp)
 2089                                 vunref(vp);
 2090                         else
 2091                                 vput(*rvp);
 2092                 }
 2093                 error = ENOENT;
 2094         }
 2095         return (error);
 2096 }
 2097 
 2098 int
 2099 vn_rlimit_fsize(const struct vnode *vp, const struct uio *uio,
 2100     struct thread *td)
 2101 {
 2102 
 2103         if (vp->v_type != VREG || td == NULL)
 2104                 return (0);
 2105         if ((uoff_t)uio->uio_offset + uio->uio_resid >
 2106             lim_cur(td, RLIMIT_FSIZE)) {
 2107                 PROC_LOCK(td->td_proc);
 2108                 kern_psignal(td->td_proc, SIGXFSZ);
 2109                 PROC_UNLOCK(td->td_proc);
 2110                 return (EFBIG);
 2111         }
 2112         return (0);
 2113 }
 2114 
 2115 int
 2116 vn_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
 2117     struct thread *td)
 2118 {
 2119         struct vnode *vp;
 2120 
 2121         vp = fp->f_vnode;
 2122 #ifdef AUDIT
 2123         vn_lock(vp, LK_SHARED | LK_RETRY);
 2124         AUDIT_ARG_VNODE1(vp);
 2125         VOP_UNLOCK(vp, 0);
 2126 #endif
 2127         return (setfmode(td, active_cred, vp, mode));
 2128 }
 2129 
 2130 int
 2131 vn_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
 2132     struct thread *td)
 2133 {
 2134         struct vnode *vp;
 2135 
 2136         vp = fp->f_vnode;
 2137 #ifdef AUDIT
 2138         vn_lock(vp, LK_SHARED | LK_RETRY);
 2139         AUDIT_ARG_VNODE1(vp);
 2140         VOP_UNLOCK(vp, 0);
 2141 #endif
 2142         return (setfown(td, active_cred, vp, uid, gid));
 2143 }
 2144 
 2145 void
 2146 vn_pages_remove(struct vnode *vp, vm_pindex_t start, vm_pindex_t end)
 2147 {
 2148         vm_object_t object;
 2149 
 2150         if ((object = vp->v_object) == NULL)
 2151                 return;
 2152         VM_OBJECT_WLOCK(object);
 2153         vm_object_page_remove(object, start, end, 0);
 2154         VM_OBJECT_WUNLOCK(object);
 2155 }
 2156 
 2157 int
 2158 vn_bmap_seekhole(struct vnode *vp, u_long cmd, off_t *off, struct ucred *cred)
 2159 {
 2160         struct vattr va;
 2161         daddr_t bn, bnp;
 2162         uint64_t bsize;
 2163         off_t noff;
 2164         int error;
 2165 
 2166         KASSERT(cmd == FIOSEEKHOLE || cmd == FIOSEEKDATA,
 2167             ("Wrong command %lu", cmd));
 2168 
 2169         if (vn_lock(vp, LK_SHARED) != 0)
 2170                 return (EBADF);
 2171         if (vp->v_type != VREG) {
 2172                 error = ENOTTY;
 2173                 goto unlock;
 2174         }
 2175         error = VOP_GETATTR(vp, &va, cred);
 2176         if (error != 0)
 2177                 goto unlock;
 2178         noff = *off;
 2179         if (noff >= va.va_size) {
 2180                 error = ENXIO;
 2181                 goto unlock;
 2182         }
 2183         bsize = vp->v_mount->mnt_stat.f_iosize;
 2184         for (bn = noff / bsize; noff < va.va_size; bn++, noff += bsize) {
 2185                 error = VOP_BMAP(vp, bn, NULL, &bnp, NULL, NULL);
 2186                 if (error == EOPNOTSUPP) {
 2187                         error = ENOTTY;
 2188                         goto unlock;
 2189                 }
 2190                 if ((bnp == -1 && cmd == FIOSEEKHOLE) ||
 2191                     (bnp != -1 && cmd == FIOSEEKDATA)) {
 2192                         noff = bn * bsize;
 2193                         if (noff < *off)
 2194                                 noff = *off;
 2195                         goto unlock;
 2196                 }
 2197         }
 2198         if (noff > va.va_size)
 2199                 noff = va.va_size;
 2200         /* noff == va.va_size. There is an implicit hole at the end of file. */
 2201         if (cmd == FIOSEEKDATA)
 2202                 error = ENXIO;
 2203 unlock:
 2204         VOP_UNLOCK(vp, 0);
 2205         if (error == 0)
 2206                 *off = noff;
 2207         return (error);
 2208 }
 2209 
 2210 int
 2211 vn_seek(struct file *fp, off_t offset, int whence, struct thread *td)
 2212 {
 2213         struct ucred *cred;
 2214         struct vnode *vp;
 2215         struct vattr vattr;
 2216         off_t foffset, size;
 2217         int error, noneg;
 2218 
 2219         cred = td->td_ucred;
 2220         vp = fp->f_vnode;
 2221         foffset = foffset_lock(fp, 0);
 2222         noneg = (vp->v_type != VCHR);
 2223         error = 0;
 2224         switch (whence) {
 2225         case L_INCR:
 2226                 if (noneg &&
 2227                     (foffset < 0 ||
 2228                     (offset > 0 && foffset > OFF_MAX - offset))) {
 2229                         error = EOVERFLOW;
 2230                         break;
 2231                 }
 2232                 offset += foffset;
 2233                 break;
 2234         case L_XTND:
 2235                 vn_lock(vp, LK_SHARED | LK_RETRY);
 2236                 error = VOP_GETATTR(vp, &vattr, cred);
 2237                 VOP_UNLOCK(vp, 0);
 2238                 if (error)
 2239                         break;
 2240 
 2241                 /*
 2242                  * If the file references a disk device, then fetch
 2243                  * the media size and use that to determine the ending
 2244                  * offset.
 2245                  */
 2246                 if (vattr.va_size == 0 && vp->v_type == VCHR &&
 2247                     fo_ioctl(fp, DIOCGMEDIASIZE, &size, cred, td) == 0)
 2248                         vattr.va_size = size;
 2249                 if (noneg &&
 2250                     (vattr.va_size > OFF_MAX ||
 2251                     (offset > 0 && vattr.va_size > OFF_MAX - offset))) {
 2252                         error = EOVERFLOW;
 2253                         break;
 2254                 }
 2255                 offset += vattr.va_size;
 2256                 break;
 2257         case L_SET:
 2258                 break;
 2259         case SEEK_DATA:
 2260                 error = fo_ioctl(fp, FIOSEEKDATA, &offset, cred, td);
 2261                 break;
 2262         case SEEK_HOLE:
 2263                 error = fo_ioctl(fp, FIOSEEKHOLE, &offset, cred, td);
 2264                 break;
 2265         default:
 2266                 error = EINVAL;
 2267         }
 2268         if (error == 0 && noneg && offset < 0)
 2269                 error = EINVAL;
 2270         if (error != 0)
 2271                 goto drop;
 2272         VFS_KNOTE_UNLOCKED(vp, 0);
 2273         td->td_uretoff.tdu_off = offset;
 2274 drop:
 2275         foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
 2276         return (error);
 2277 }
 2278 
 2279 int
 2280 vn_utimes_perm(struct vnode *vp, struct vattr *vap, struct ucred *cred,
 2281     struct thread *td)
 2282 {
 2283         int error;
 2284 
 2285         /*
 2286          * Grant permission if the caller is the owner of the file, or
 2287          * the super-user, or has ACL_WRITE_ATTRIBUTES permission on
 2288          * on the file.  If the time pointer is null, then write
 2289          * permission on the file is also sufficient.
 2290          *
 2291          * From NFSv4.1, draft 21, 6.2.1.3.1, Discussion of Mask Attributes:
 2292          * A user having ACL_WRITE_DATA or ACL_WRITE_ATTRIBUTES
 2293          * will be allowed to set the times [..] to the current
 2294          * server time.
 2295          */
 2296         error = VOP_ACCESSX(vp, VWRITE_ATTRIBUTES, cred, td);
 2297         if (error != 0 && (vap->va_vaflags & VA_UTIMES_NULL) != 0)
 2298                 error = VOP_ACCESS(vp, VWRITE, cred, td);
 2299         return (error);
 2300 }
 2301 
 2302 int
 2303 vn_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
 2304 {
 2305         struct vnode *vp;
 2306         int error;
 2307 
 2308         if (fp->f_type == DTYPE_FIFO)
 2309                 kif->kf_type = KF_TYPE_FIFO;
 2310         else
 2311                 kif->kf_type = KF_TYPE_VNODE;
 2312         vp = fp->f_vnode;
 2313         vref(vp);
 2314         FILEDESC_SUNLOCK(fdp);
 2315         error = vn_fill_kinfo_vnode(vp, kif);
 2316         vrele(vp);
 2317         FILEDESC_SLOCK(fdp);
 2318         return (error);
 2319 }
 2320 
 2321 static inline void
 2322 vn_fill_junk(struct kinfo_file *kif)
 2323 {
 2324         size_t len, olen;
 2325 
 2326         /*
 2327          * Simulate vn_fullpath returning changing values for a given
 2328          * vp during e.g. coredump.
 2329          */
 2330         len = (arc4random() % (sizeof(kif->kf_path) - 2)) + 1;
 2331         olen = strlen(kif->kf_path);
 2332         if (len < olen)
 2333                 strcpy(&kif->kf_path[len - 1], "$");
 2334         else
 2335                 for (; olen < len; olen++)
 2336                         strcpy(&kif->kf_path[olen], "A");
 2337 }
 2338 
 2339 int
 2340 vn_fill_kinfo_vnode(struct vnode *vp, struct kinfo_file *kif)
 2341 {
 2342         struct vattr va;
 2343         char *fullpath, *freepath;
 2344         int error;
 2345 
 2346         kif->kf_vnode_type = vntype_to_kinfo(vp->v_type);
 2347         freepath = NULL;
 2348         fullpath = "-";
 2349         error = vn_fullpath(curthread, vp, &fullpath, &freepath);
 2350         if (error == 0) {
 2351                 strlcpy(kif->kf_path, fullpath, sizeof(kif->kf_path));
 2352         }
 2353         if (freepath != NULL)
 2354                 free(freepath, M_TEMP);
 2355 
 2356         KFAIL_POINT_CODE(DEBUG_FP, fill_kinfo_vnode__random_path,
 2357                 vn_fill_junk(kif);
 2358         );
 2359 
 2360         /*
 2361          * Retrieve vnode attributes.
 2362          */
 2363         va.va_fsid = VNOVAL;
 2364         va.va_rdev = NODEV;
 2365         vn_lock(vp, LK_SHARED | LK_RETRY);
 2366         error = VOP_GETATTR(vp, &va, curthread->td_ucred);
 2367         VOP_UNLOCK(vp, 0);
 2368         if (error != 0)
 2369                 return (error);
 2370         if (va.va_fsid != VNOVAL)
 2371                 kif->kf_un.kf_file.kf_file_fsid = va.va_fsid;
 2372         else
 2373                 kif->kf_un.kf_file.kf_file_fsid =
 2374                     vp->v_mount->mnt_stat.f_fsid.val[0];
 2375         kif->kf_un.kf_file.kf_file_fileid = va.va_fileid;
 2376         kif->kf_un.kf_file.kf_file_mode = MAKEIMODE(va.va_type, va.va_mode);
 2377         kif->kf_un.kf_file.kf_file_size = va.va_size;
 2378         kif->kf_un.kf_file.kf_file_rdev = va.va_rdev;
 2379         return (0);
 2380 }
 2381 
 2382 int
 2383 vn_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t size,
 2384     vm_prot_t prot, vm_prot_t cap_maxprot, int flags, vm_ooffset_t foff,
 2385     struct thread *td)
 2386 {
 2387 #ifdef HWPMC_HOOKS
 2388         struct pmckern_map_in pkm;
 2389 #endif
 2390         struct mount *mp;
 2391         struct vnode *vp;
 2392         vm_object_t object;
 2393         vm_prot_t maxprot;
 2394         boolean_t writecounted;
 2395         int error;
 2396 
 2397 #if defined(COMPAT_FREEBSD7) || defined(COMPAT_FREEBSD6) || \
 2398     defined(COMPAT_FREEBSD5) || defined(COMPAT_FREEBSD4)
 2399         /*
 2400          * POSIX shared-memory objects are defined to have
 2401          * kernel persistence, and are not defined to support
 2402          * read(2)/write(2) -- or even open(2).  Thus, we can
 2403          * use MAP_ASYNC to trade on-disk coherence for speed.
 2404          * The shm_open(3) library routine turns on the FPOSIXSHM
 2405          * flag to request this behavior.
 2406          */
 2407         if ((fp->f_flag & FPOSIXSHM) != 0)
 2408                 flags |= MAP_NOSYNC;
 2409 #endif
 2410         vp = fp->f_vnode;
 2411 
 2412         /*
 2413          * Ensure that file and memory protections are
 2414          * compatible.  Note that we only worry about
 2415          * writability if mapping is shared; in this case,
 2416          * current and max prot are dictated by the open file.
 2417          * XXX use the vnode instead?  Problem is: what
 2418          * credentials do we use for determination? What if
 2419          * proc does a setuid?
 2420          */
 2421         mp = vp->v_mount;
 2422         if (mp != NULL && (mp->mnt_flag & MNT_NOEXEC) != 0)
 2423                 maxprot = VM_PROT_NONE;
 2424         else
 2425                 maxprot = VM_PROT_EXECUTE;
 2426         if ((fp->f_flag & FREAD) != 0)
 2427                 maxprot |= VM_PROT_READ;
 2428         else if ((prot & VM_PROT_READ) != 0)
 2429                 return (EACCES);
 2430 
 2431         /*
 2432          * If we are sharing potential changes via MAP_SHARED and we
 2433          * are trying to get write permission although we opened it
 2434          * without asking for it, bail out.
 2435          */
 2436         if ((flags & MAP_SHARED) != 0) {
 2437                 if ((fp->f_flag & FWRITE) != 0)
 2438                         maxprot |= VM_PROT_WRITE;
 2439                 else if ((prot & VM_PROT_WRITE) != 0)
 2440                         return (EACCES);
 2441         } else {
 2442                 maxprot |= VM_PROT_WRITE;
 2443                 cap_maxprot |= VM_PROT_WRITE;
 2444         }
 2445         maxprot &= cap_maxprot;
 2446 
 2447         writecounted = FALSE;
 2448         error = vm_mmap_vnode(td, size, prot, &maxprot, &flags, vp,
 2449             &foff, &object, &writecounted);
 2450         if (error != 0)
 2451                 return (error);
 2452         error = vm_mmap_object(map, addr, size, prot, maxprot, flags, object,
 2453             foff, writecounted, td);
 2454         if (error != 0) {
 2455                 /*
 2456                  * If this mapping was accounted for in the vnode's
 2457                  * writecount, then undo that now.
 2458                  */
 2459                 if (writecounted)
 2460                         vnode_pager_release_writecount(object, 0, size);
 2461                 vm_object_deallocate(object);
 2462         }
 2463 #ifdef HWPMC_HOOKS
 2464         /* Inform hwpmc(4) if an executable is being mapped. */
 2465         if (error == 0 && (prot & VM_PROT_EXECUTE) != 0) {
 2466                 pkm.pm_file = vp;
 2467                 pkm.pm_address = (uintptr_t) *addr;
 2468                 PMC_CALL_HOOK(td, PMC_FN_MMAP, (void *) &pkm);
 2469         }
 2470 #endif
 2471         return (error);
 2472 }

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