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: stable/10/sys/kern/vfs_vnops.c 338605 2018-09-12 05:03:30Z gordon $");
   45 
   46 #include <sys/param.h>
   47 #include <sys/systm.h>
   48 #include <sys/disk.h>
   49 #include <sys/fcntl.h>
   50 #include <sys/file.h>
   51 #include <sys/kdb.h>
   52 #include <sys/stat.h>
   53 #include <sys/priv.h>
   54 #include <sys/proc.h>
   55 #include <sys/limits.h>
   56 #include <sys/lock.h>
   57 #include <sys/mount.h>
   58 #include <sys/mutex.h>
   59 #include <sys/namei.h>
   60 #include <sys/vnode.h>
   61 #include <sys/bio.h>
   62 #include <sys/buf.h>
   63 #include <sys/filio.h>
   64 #include <sys/resourcevar.h>
   65 #include <sys/rwlock.h>
   66 #include <sys/sx.h>
   67 #include <sys/sysctl.h>
   68 #include <sys/ttycom.h>
   69 #include <sys/conf.h>
   70 #include <sys/syslog.h>
   71 #include <sys/unistd.h>
   72 
   73 #include <security/audit/audit.h>
   74 #include <security/mac/mac_framework.h>
   75 
   76 #include <vm/vm.h>
   77 #include <vm/vm_extern.h>
   78 #include <vm/pmap.h>
   79 #include <vm/vm_map.h>
   80 #include <vm/vm_object.h>
   81 #include <vm/vm_page.h>
   82 
   83 static fo_rdwr_t        vn_read;
   84 static fo_rdwr_t        vn_write;
   85 static fo_rdwr_t        vn_io_fault;
   86 static fo_truncate_t    vn_truncate;
   87 static fo_ioctl_t       vn_ioctl;
   88 static fo_poll_t        vn_poll;
   89 static fo_kqfilter_t    vn_kqfilter;
   90 static fo_stat_t        vn_statfile;
   91 static fo_close_t       vn_closefile;
   92 
   93 struct  fileops vnops = {
   94         .fo_read = vn_io_fault,
   95         .fo_write = vn_io_fault,
   96         .fo_truncate = vn_truncate,
   97         .fo_ioctl = vn_ioctl,
   98         .fo_poll = vn_poll,
   99         .fo_kqfilter = vn_kqfilter,
  100         .fo_stat = vn_statfile,
  101         .fo_close = vn_closefile,
  102         .fo_chmod = vn_chmod,
  103         .fo_chown = vn_chown,
  104         .fo_sendfile = vn_sendfile,
  105         .fo_seek = vn_seek,
  106         .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE
  107 };
  108 
  109 static const int io_hold_cnt = 16;
  110 static int vn_io_fault_enable = 1;
  111 SYSCTL_INT(_debug, OID_AUTO, vn_io_fault_enable, CTLFLAG_RW,
  112     &vn_io_fault_enable, 0, "Enable vn_io_fault lock avoidance");
  113 static int vn_io_fault_prefault = 0;
  114 SYSCTL_INT(_debug, OID_AUTO, vn_io_fault_prefault, CTLFLAG_RW,
  115     &vn_io_fault_prefault, 0, "Enable vn_io_fault prefaulting");
  116 static u_long vn_io_faults_cnt;
  117 SYSCTL_ULONG(_debug, OID_AUTO, vn_io_faults, CTLFLAG_RD,
  118     &vn_io_faults_cnt, 0, "Count of vn_io_fault lock avoidance triggers");
  119 
  120 /*
  121  * Returns true if vn_io_fault mode of handling the i/o request should
  122  * be used.
  123  */
  124 static bool
  125 do_vn_io_fault(struct vnode *vp, struct uio *uio)
  126 {
  127         struct mount *mp;
  128 
  129         return (uio->uio_segflg == UIO_USERSPACE && vp->v_type == VREG &&
  130             (mp = vp->v_mount) != NULL &&
  131             (mp->mnt_kern_flag & MNTK_NO_IOPF) != 0 && vn_io_fault_enable);
  132 }
  133 
  134 /*
  135  * Structure used to pass arguments to vn_io_fault1(), to do either
  136  * file- or vnode-based I/O calls.
  137  */
  138 struct vn_io_fault_args {
  139         enum {
  140                 VN_IO_FAULT_FOP,
  141                 VN_IO_FAULT_VOP
  142         } kind;
  143         struct ucred *cred;
  144         int flags;
  145         union {
  146                 struct fop_args_tag {
  147                         struct file *fp;
  148                         fo_rdwr_t *doio;
  149                 } fop_args;
  150                 struct vop_args_tag {
  151                         struct vnode *vp;
  152                 } vop_args;
  153         } args;
  154 };
  155 
  156 static int vn_io_fault1(struct vnode *vp, struct uio *uio,
  157     struct vn_io_fault_args *args, struct thread *td);
  158 
  159 int
  160 vn_open(ndp, flagp, cmode, fp)
  161         struct nameidata *ndp;
  162         int *flagp, cmode;
  163         struct file *fp;
  164 {
  165         struct thread *td = ndp->ni_cnd.cn_thread;
  166 
  167         return (vn_open_cred(ndp, flagp, cmode, 0, td->td_ucred, fp));
  168 }
  169 
  170 /*
  171  * Common code for vnode open operations via a name lookup.
  172  * Lookup the vnode and invoke VOP_CREATE if needed.
  173  * Check permissions, and call the VOP_OPEN or VOP_CREATE routine.
  174  * 
  175  * Note that this does NOT free nameidata for the successful case,
  176  * due to the NDINIT being done elsewhere.
  177  */
  178 int
  179 vn_open_cred(struct nameidata *ndp, int *flagp, int cmode, u_int vn_open_flags,
  180     struct ucred *cred, struct file *fp)
  181 {
  182         struct vnode *vp;
  183         struct mount *mp;
  184         struct thread *td = ndp->ni_cnd.cn_thread;
  185         struct vattr vat;
  186         struct vattr *vap = &vat;
  187         int fmode, error;
  188 
  189 restart:
  190         fmode = *flagp;
  191         if ((fmode & (O_CREAT | O_EXCL | O_DIRECTORY)) == (O_CREAT |
  192             O_EXCL | O_DIRECTORY))
  193                 return (EINVAL);
  194         else if ((fmode & (O_CREAT | O_DIRECTORY)) == O_CREAT) {
  195                 ndp->ni_cnd.cn_nameiop = CREATE;
  196                 /*
  197                  * Set NOCACHE to avoid flushing the cache when
  198                  * rolling in many files at once.
  199                 */
  200                 ndp->ni_cnd.cn_flags = ISOPEN | LOCKPARENT | LOCKLEAF | NOCACHE;
  201                 if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
  202                         ndp->ni_cnd.cn_flags |= FOLLOW;
  203                 if (!(vn_open_flags & VN_OPEN_NOAUDIT))
  204                         ndp->ni_cnd.cn_flags |= AUDITVNODE1;
  205                 if (vn_open_flags & VN_OPEN_NOCAPCHECK)
  206                         ndp->ni_cnd.cn_flags |= NOCAPCHECK;
  207                 bwillwrite();
  208                 if ((error = namei(ndp)) != 0)
  209                         return (error);
  210                 if (ndp->ni_vp == NULL) {
  211                         VATTR_NULL(vap);
  212                         vap->va_type = VREG;
  213                         vap->va_mode = cmode;
  214                         if (fmode & O_EXCL)
  215                                 vap->va_vaflags |= VA_EXCLUSIVE;
  216                         if (vn_start_write(ndp->ni_dvp, &mp, V_NOWAIT) != 0) {
  217                                 NDFREE(ndp, NDF_ONLY_PNBUF);
  218                                 vput(ndp->ni_dvp);
  219                                 if ((error = vn_start_write(NULL, &mp,
  220                                     V_XSLEEP | PCATCH)) != 0)
  221                                         return (error);
  222                                 goto restart;
  223                         }
  224                         if ((vn_open_flags & VN_OPEN_NAMECACHE) != 0)
  225                                 ndp->ni_cnd.cn_flags |= MAKEENTRY;
  226 #ifdef MAC
  227                         error = mac_vnode_check_create(cred, ndp->ni_dvp,
  228                             &ndp->ni_cnd, vap);
  229                         if (error == 0)
  230 #endif
  231                                 error = VOP_CREATE(ndp->ni_dvp, &ndp->ni_vp,
  232                                                    &ndp->ni_cnd, vap);
  233                         vput(ndp->ni_dvp);
  234                         vn_finished_write(mp);
  235                         if (error) {
  236                                 NDFREE(ndp, NDF_ONLY_PNBUF);
  237                                 return (error);
  238                         }
  239                         fmode &= ~O_TRUNC;
  240                         vp = ndp->ni_vp;
  241                 } else {
  242                         if (ndp->ni_dvp == ndp->ni_vp)
  243                                 vrele(ndp->ni_dvp);
  244                         else
  245                                 vput(ndp->ni_dvp);
  246                         ndp->ni_dvp = NULL;
  247                         vp = ndp->ni_vp;
  248                         if (fmode & O_EXCL) {
  249                                 error = EEXIST;
  250                                 goto bad;
  251                         }
  252                         fmode &= ~O_CREAT;
  253                 }
  254         } else {
  255                 ndp->ni_cnd.cn_nameiop = LOOKUP;
  256                 ndp->ni_cnd.cn_flags = ISOPEN |
  257                     ((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) | LOCKLEAF;
  258                 if (!(fmode & FWRITE))
  259                         ndp->ni_cnd.cn_flags |= LOCKSHARED;
  260                 if (!(vn_open_flags & VN_OPEN_NOAUDIT))
  261                         ndp->ni_cnd.cn_flags |= AUDITVNODE1;
  262                 if (vn_open_flags & VN_OPEN_NOCAPCHECK)
  263                         ndp->ni_cnd.cn_flags |= NOCAPCHECK;
  264                 if ((error = namei(ndp)) != 0)
  265                         return (error);
  266                 vp = ndp->ni_vp;
  267         }
  268         error = vn_open_vnode(vp, fmode, cred, td, fp);
  269         if (error)
  270                 goto bad;
  271         *flagp = fmode;
  272         return (0);
  273 bad:
  274         NDFREE(ndp, NDF_ONLY_PNBUF);
  275         vput(vp);
  276         *flagp = fmode;
  277         ndp->ni_vp = NULL;
  278         return (error);
  279 }
  280 
  281 /*
  282  * Common code for vnode open operations once a vnode is located.
  283  * Check permissions, and call the VOP_OPEN routine.
  284  */
  285 int
  286 vn_open_vnode(struct vnode *vp, int fmode, struct ucred *cred,
  287     struct thread *td, struct file *fp)
  288 {
  289         struct mount *mp;
  290         accmode_t accmode;
  291         struct flock lf;
  292         int error, have_flock, lock_flags, type;
  293 
  294         if (vp->v_type == VLNK)
  295                 return (EMLINK);
  296         if (vp->v_type == VSOCK)
  297                 return (EOPNOTSUPP);
  298         if (vp->v_type != VDIR && fmode & O_DIRECTORY)
  299                 return (ENOTDIR);
  300         accmode = 0;
  301         if (fmode & (FWRITE | O_TRUNC)) {
  302                 if (vp->v_type == VDIR)
  303                         return (EISDIR);
  304                 accmode |= VWRITE;
  305         }
  306         if (fmode & FREAD)
  307                 accmode |= VREAD;
  308         if (fmode & FEXEC)
  309                 accmode |= VEXEC;
  310         if ((fmode & O_APPEND) && (fmode & FWRITE))
  311                 accmode |= VAPPEND;
  312 #ifdef MAC
  313         error = mac_vnode_check_open(cred, vp, accmode);
  314         if (error)
  315                 return (error);
  316 #endif
  317         if ((fmode & O_CREAT) == 0) {
  318                 if (accmode & VWRITE) {
  319                         error = vn_writechk(vp);
  320                         if (error)
  321                                 return (error);
  322                 }
  323                 if (accmode) {
  324                         error = VOP_ACCESS(vp, accmode, cred, td);
  325                         if (error)
  326                                 return (error);
  327                 }
  328         }
  329         if (vp->v_type == VFIFO && VOP_ISLOCKED(vp) != LK_EXCLUSIVE)
  330                 vn_lock(vp, LK_UPGRADE | LK_RETRY);
  331         if ((error = VOP_OPEN(vp, fmode, cred, td, fp)) != 0)
  332                 return (error);
  333 
  334         if (fmode & (O_EXLOCK | O_SHLOCK)) {
  335                 KASSERT(fp != NULL, ("open with flock requires fp"));
  336                 lock_flags = VOP_ISLOCKED(vp);
  337                 VOP_UNLOCK(vp, 0);
  338                 lf.l_whence = SEEK_SET;
  339                 lf.l_start = 0;
  340                 lf.l_len = 0;
  341                 if (fmode & O_EXLOCK)
  342                         lf.l_type = F_WRLCK;
  343                 else
  344                         lf.l_type = F_RDLCK;
  345                 type = F_FLOCK;
  346                 if ((fmode & FNONBLOCK) == 0)
  347                         type |= F_WAIT;
  348                 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, type);
  349                 have_flock = (error == 0);
  350                 vn_lock(vp, lock_flags | LK_RETRY);
  351                 if (error == 0 && vp->v_iflag & VI_DOOMED)
  352                         error = ENOENT;
  353                 /*
  354                  * Another thread might have used this vnode as an
  355                  * executable while the vnode lock was dropped.
  356                  * Ensure the vnode is still able to be opened for
  357                  * writing after the lock has been obtained.
  358                  */
  359                 if (error == 0 && accmode & VWRITE)
  360                         error = vn_writechk(vp);
  361                 if (error) {
  362                         VOP_UNLOCK(vp, 0);
  363                         if (have_flock) {
  364                                 lf.l_whence = SEEK_SET;
  365                                 lf.l_start = 0;
  366                                 lf.l_len = 0;
  367                                 lf.l_type = F_UNLCK;
  368                                 (void) VOP_ADVLOCK(vp, fp, F_UNLCK, &lf,
  369                                     F_FLOCK);
  370                         }
  371                         vn_start_write(vp, &mp, V_WAIT);
  372                         vn_lock(vp, lock_flags | LK_RETRY);
  373                         (void)VOP_CLOSE(vp, fmode, cred, td);
  374                         vn_finished_write(mp);
  375                         /* Prevent second close from fdrop()->vn_close(). */
  376                         if (fp != NULL)
  377                                 fp->f_ops= &badfileops;
  378                         return (error);
  379                 }
  380                 fp->f_flag |= FHASLOCK;
  381         }
  382         if (fmode & FWRITE) {
  383                 VOP_ADD_WRITECOUNT(vp, 1);
  384                 CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d",
  385                     __func__, vp, vp->v_writecount);
  386         }
  387         ASSERT_VOP_LOCKED(vp, "vn_open_vnode");
  388         return (0);
  389 }
  390 
  391 /*
  392  * Check for write permissions on the specified vnode.
  393  * Prototype text segments cannot be written.
  394  */
  395 int
  396 vn_writechk(vp)
  397         register struct vnode *vp;
  398 {
  399 
  400         ASSERT_VOP_LOCKED(vp, "vn_writechk");
  401         /*
  402          * If there's shared text associated with
  403          * the vnode, try to free it up once.  If
  404          * we fail, we can't allow writing.
  405          */
  406         if (VOP_IS_TEXT(vp))
  407                 return (ETXTBSY);
  408 
  409         return (0);
  410 }
  411 
  412 /*
  413  * Vnode close call
  414  */
  415 static int
  416 vn_close1(struct vnode *vp, int flags, struct ucred *file_cred,
  417     struct thread *td, bool keep_ref)
  418 {
  419         struct mount *mp;
  420         int error, lock_flags;
  421 
  422         if (vp->v_type != VFIFO && (flags & FWRITE) == 0 &&
  423             MNT_EXTENDED_SHARED(vp->v_mount))
  424                 lock_flags = LK_SHARED;
  425         else
  426                 lock_flags = LK_EXCLUSIVE;
  427 
  428         vn_start_write(vp, &mp, V_WAIT);
  429         vn_lock(vp, lock_flags | LK_RETRY);
  430         if (flags & FWRITE) {
  431                 VNASSERT(vp->v_writecount > 0, vp, 
  432                     ("vn_close: negative writecount"));
  433                 VOP_ADD_WRITECOUNT(vp, -1);
  434                 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
  435                     __func__, vp, vp->v_writecount);
  436         }
  437         error = VOP_CLOSE(vp, flags, file_cred, td);
  438         if (keep_ref)
  439                 VOP_UNLOCK(vp, 0);
  440         else
  441                 vput(vp);
  442         vn_finished_write(mp);
  443         return (error);
  444 }
  445 
  446 int
  447 vn_close(struct vnode *vp, int flags, struct ucred *file_cred,
  448     struct thread *td)
  449 {
  450 
  451         return (vn_close1(vp, flags, file_cred, td, false));
  452 }
  453 
  454 /*
  455  * Heuristic to detect sequential operation.
  456  */
  457 static int
  458 sequential_heuristic(struct uio *uio, struct file *fp)
  459 {
  460 
  461         ASSERT_VOP_LOCKED(fp->f_vnode, __func__);
  462         if (fp->f_flag & FRDAHEAD)
  463                 return (fp->f_seqcount << IO_SEQSHIFT);
  464 
  465         /*
  466          * Offset 0 is handled specially.  open() sets f_seqcount to 1 so
  467          * that the first I/O is normally considered to be slightly
  468          * sequential.  Seeking to offset 0 doesn't change sequentiality
  469          * unless previous seeks have reduced f_seqcount to 0, in which
  470          * case offset 0 is not special.
  471          */
  472         if ((uio->uio_offset == 0 && fp->f_seqcount > 0) ||
  473             uio->uio_offset == fp->f_nextoff) {
  474                 /*
  475                  * f_seqcount is in units of fixed-size blocks so that it
  476                  * depends mainly on the amount of sequential I/O and not
  477                  * much on the number of sequential I/O's.  The fixed size
  478                  * of 16384 is hard-coded here since it is (not quite) just
  479                  * a magic size that works well here.  This size is more
  480                  * closely related to the best I/O size for real disks than
  481                  * to any block size used by software.
  482                  */
  483                 fp->f_seqcount += howmany(uio->uio_resid, 16384);
  484                 if (fp->f_seqcount > IO_SEQMAX)
  485                         fp->f_seqcount = IO_SEQMAX;
  486                 return (fp->f_seqcount << IO_SEQSHIFT);
  487         }
  488 
  489         /* Not sequential.  Quickly draw-down sequentiality. */
  490         if (fp->f_seqcount > 1)
  491                 fp->f_seqcount = 1;
  492         else
  493                 fp->f_seqcount = 0;
  494         return (0);
  495 }
  496 
  497 /*
  498  * Package up an I/O request on a vnode into a uio and do it.
  499  */
  500 int
  501 vn_rdwr(enum uio_rw rw, struct vnode *vp, void *base, int len, off_t offset,
  502     enum uio_seg segflg, int ioflg, struct ucred *active_cred,
  503     struct ucred *file_cred, ssize_t *aresid, struct thread *td)
  504 {
  505         struct uio auio;
  506         struct iovec aiov;
  507         struct mount *mp;
  508         struct ucred *cred;
  509         void *rl_cookie;
  510         struct vn_io_fault_args args;
  511         int error, lock_flags;
  512 
  513         if (offset < 0 && vp->v_type != VCHR)
  514                 return (EINVAL);
  515         auio.uio_iov = &aiov;
  516         auio.uio_iovcnt = 1;
  517         aiov.iov_base = base;
  518         aiov.iov_len = len;
  519         auio.uio_resid = len;
  520         auio.uio_offset = offset;
  521         auio.uio_segflg = segflg;
  522         auio.uio_rw = rw;
  523         auio.uio_td = td;
  524         error = 0;
  525 
  526         if ((ioflg & IO_NODELOCKED) == 0) {
  527                 if ((ioflg & IO_RANGELOCKED) == 0) {
  528                         if (rw == UIO_READ) {
  529                                 rl_cookie = vn_rangelock_rlock(vp, offset,
  530                                     offset + len);
  531                         } else {
  532                                 rl_cookie = vn_rangelock_wlock(vp, offset,
  533                                     offset + len);
  534                         }
  535                 } else
  536                         rl_cookie = NULL;
  537                 mp = NULL;
  538                 if (rw == UIO_WRITE) { 
  539                         if (vp->v_type != VCHR &&
  540                             (error = vn_start_write(vp, &mp, V_WAIT | PCATCH))
  541                             != 0)
  542                                 goto out;
  543                         if (MNT_SHARED_WRITES(mp) ||
  544                             ((mp == NULL) && MNT_SHARED_WRITES(vp->v_mount)))
  545                                 lock_flags = LK_SHARED;
  546                         else
  547                                 lock_flags = LK_EXCLUSIVE;
  548                 } else
  549                         lock_flags = LK_SHARED;
  550                 vn_lock(vp, lock_flags | LK_RETRY);
  551         } else
  552                 rl_cookie = NULL;
  553 
  554         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
  555 #ifdef MAC
  556         if ((ioflg & IO_NOMACCHECK) == 0) {
  557                 if (rw == UIO_READ)
  558                         error = mac_vnode_check_read(active_cred, file_cred,
  559                             vp);
  560                 else
  561                         error = mac_vnode_check_write(active_cred, file_cred,
  562                             vp);
  563         }
  564 #endif
  565         if (error == 0) {
  566                 if (file_cred != NULL)
  567                         cred = file_cred;
  568                 else
  569                         cred = active_cred;
  570                 if (do_vn_io_fault(vp, &auio)) {
  571                         args.kind = VN_IO_FAULT_VOP;
  572                         args.cred = cred;
  573                         args.flags = ioflg;
  574                         args.args.vop_args.vp = vp;
  575                         error = vn_io_fault1(vp, &auio, &args, td);
  576                 } else if (rw == UIO_READ) {
  577                         error = VOP_READ(vp, &auio, ioflg, cred);
  578                 } else /* if (rw == UIO_WRITE) */ {
  579                         error = VOP_WRITE(vp, &auio, ioflg, cred);
  580                 }
  581         }
  582         if (aresid)
  583                 *aresid = auio.uio_resid;
  584         else
  585                 if (auio.uio_resid && error == 0)
  586                         error = EIO;
  587         if ((ioflg & IO_NODELOCKED) == 0) {
  588                 VOP_UNLOCK(vp, 0);
  589                 if (mp != NULL)
  590                         vn_finished_write(mp);
  591         }
  592  out:
  593         if (rl_cookie != NULL)
  594                 vn_rangelock_unlock(vp, rl_cookie);
  595         return (error);
  596 }
  597 
  598 /*
  599  * Package up an I/O request on a vnode into a uio and do it.  The I/O
  600  * request is split up into smaller chunks and we try to avoid saturating
  601  * the buffer cache while potentially holding a vnode locked, so we 
  602  * check bwillwrite() before calling vn_rdwr().  We also call kern_yield()
  603  * to give other processes a chance to lock the vnode (either other processes
  604  * core'ing the same binary, or unrelated processes scanning the directory).
  605  */
  606 int
  607 vn_rdwr_inchunks(rw, vp, base, len, offset, segflg, ioflg, active_cred,
  608     file_cred, aresid, td)
  609         enum uio_rw rw;
  610         struct vnode *vp;
  611         void *base;
  612         size_t len;
  613         off_t offset;
  614         enum uio_seg segflg;
  615         int ioflg;
  616         struct ucred *active_cred;
  617         struct ucred *file_cred;
  618         size_t *aresid;
  619         struct thread *td;
  620 {
  621         int error = 0;
  622         ssize_t iaresid;
  623 
  624         do {
  625                 int chunk;
  626 
  627                 /*
  628                  * Force `offset' to a multiple of MAXBSIZE except possibly
  629                  * for the first chunk, so that filesystems only need to
  630                  * write full blocks except possibly for the first and last
  631                  * chunks.
  632                  */
  633                 chunk = MAXBSIZE - (uoff_t)offset % MAXBSIZE;
  634 
  635                 if (chunk > len)
  636                         chunk = len;
  637                 if (rw != UIO_READ && vp->v_type == VREG)
  638                         bwillwrite();
  639                 iaresid = 0;
  640                 error = vn_rdwr(rw, vp, base, chunk, offset, segflg,
  641                     ioflg, active_cred, file_cred, &iaresid, td);
  642                 len -= chunk;   /* aresid calc already includes length */
  643                 if (error)
  644                         break;
  645                 offset += chunk;
  646                 base = (char *)base + chunk;
  647                 kern_yield(PRI_USER);
  648         } while (len);
  649         if (aresid)
  650                 *aresid = len + iaresid;
  651         return (error);
  652 }
  653 
  654 off_t
  655 foffset_lock(struct file *fp, int flags)
  656 {
  657         struct mtx *mtxp;
  658         off_t res;
  659 
  660         KASSERT((flags & FOF_OFFSET) == 0, ("FOF_OFFSET passed"));
  661 
  662 #if OFF_MAX <= LONG_MAX
  663         /*
  664          * Caller only wants the current f_offset value.  Assume that
  665          * the long and shorter integer types reads are atomic.
  666          */
  667         if ((flags & FOF_NOLOCK) != 0)
  668                 return (fp->f_offset);
  669 #endif
  670 
  671         /*
  672          * According to McKusick the vn lock was protecting f_offset here.
  673          * It is now protected by the FOFFSET_LOCKED flag.
  674          */
  675         mtxp = mtx_pool_find(mtxpool_sleep, fp);
  676         mtx_lock(mtxp);
  677         if ((flags & FOF_NOLOCK) == 0) {
  678                 while (fp->f_vnread_flags & FOFFSET_LOCKED) {
  679                         fp->f_vnread_flags |= FOFFSET_LOCK_WAITING;
  680                         msleep(&fp->f_vnread_flags, mtxp, PUSER -1,
  681                             "vofflock", 0);
  682                 }
  683                 fp->f_vnread_flags |= FOFFSET_LOCKED;
  684         }
  685         res = fp->f_offset;
  686         mtx_unlock(mtxp);
  687         return (res);
  688 }
  689 
  690 void
  691 foffset_unlock(struct file *fp, off_t val, int flags)
  692 {
  693         struct mtx *mtxp;
  694 
  695         KASSERT((flags & FOF_OFFSET) == 0, ("FOF_OFFSET passed"));
  696 
  697 #if OFF_MAX <= LONG_MAX
  698         if ((flags & FOF_NOLOCK) != 0) {
  699                 if ((flags & FOF_NOUPDATE) == 0)
  700                         fp->f_offset = val;
  701                 if ((flags & FOF_NEXTOFF) != 0)
  702                         fp->f_nextoff = val;
  703                 return;
  704         }
  705 #endif
  706 
  707         mtxp = mtx_pool_find(mtxpool_sleep, fp);
  708         mtx_lock(mtxp);
  709         if ((flags & FOF_NOUPDATE) == 0)
  710                 fp->f_offset = val;
  711         if ((flags & FOF_NEXTOFF) != 0)
  712                 fp->f_nextoff = val;
  713         if ((flags & FOF_NOLOCK) == 0) {
  714                 KASSERT((fp->f_vnread_flags & FOFFSET_LOCKED) != 0,
  715                     ("Lost FOFFSET_LOCKED"));
  716                 if (fp->f_vnread_flags & FOFFSET_LOCK_WAITING)
  717                         wakeup(&fp->f_vnread_flags);
  718                 fp->f_vnread_flags = 0;
  719         }
  720         mtx_unlock(mtxp);
  721 }
  722 
  723 void
  724 foffset_lock_uio(struct file *fp, struct uio *uio, int flags)
  725 {
  726 
  727         if ((flags & FOF_OFFSET) == 0)
  728                 uio->uio_offset = foffset_lock(fp, flags);
  729 }
  730 
  731 void
  732 foffset_unlock_uio(struct file *fp, struct uio *uio, int flags)
  733 {
  734 
  735         if ((flags & FOF_OFFSET) == 0)
  736                 foffset_unlock(fp, uio->uio_offset, flags);
  737 }
  738 
  739 static int
  740 get_advice(struct file *fp, struct uio *uio)
  741 {
  742         struct mtx *mtxp;
  743         int ret;
  744 
  745         ret = POSIX_FADV_NORMAL;
  746         if (fp->f_advice == NULL || fp->f_vnode->v_type != VREG)
  747                 return (ret);
  748 
  749         mtxp = mtx_pool_find(mtxpool_sleep, fp);
  750         mtx_lock(mtxp);
  751         if (fp->f_advice != NULL &&
  752             uio->uio_offset >= fp->f_advice->fa_start &&
  753             uio->uio_offset + uio->uio_resid <= fp->f_advice->fa_end)
  754                 ret = fp->f_advice->fa_advice;
  755         mtx_unlock(mtxp);
  756         return (ret);
  757 }
  758 
  759 /*
  760  * File table vnode read routine.
  761  */
  762 static int
  763 vn_read(fp, uio, active_cred, flags, td)
  764         struct file *fp;
  765         struct uio *uio;
  766         struct ucred *active_cred;
  767         int flags;
  768         struct thread *td;
  769 {
  770         struct vnode *vp;
  771         struct mtx *mtxp;
  772         int error, ioflag;
  773         int advice;
  774         off_t offset, start, end;
  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         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             offset != uio->uio_offset) {
  809                 /*
  810                  * Use POSIX_FADV_DONTNEED to flush clean pages and
  811                  * buffers for the backing file after a
  812                  * POSIX_FADV_NOREUSE read(2).  To optimize the common
  813                  * case of using POSIX_FADV_NOREUSE with sequential
  814                  * access, track the previous implicit DONTNEED
  815                  * request and grow this request to include the
  816                  * current read(2) in addition to the previous
  817                  * DONTNEED.  With purely sequential access this will
  818                  * cause the DONTNEED requests to continously grow to
  819                  * cover all of the previously read regions of the
  820                  * file.  This allows filesystem blocks that are
  821                  * accessed by multiple calls to read(2) to be flushed
  822                  * once the last read(2) finishes.
  823                  */
  824                 start = offset;
  825                 end = uio->uio_offset - 1;
  826                 mtxp = mtx_pool_find(mtxpool_sleep, fp);
  827                 mtx_lock(mtxp);
  828                 if (fp->f_advice != NULL &&
  829                     fp->f_advice->fa_advice == POSIX_FADV_NOREUSE) {
  830                         if (start != 0 && fp->f_advice->fa_prevend + 1 == start)
  831                                 start = fp->f_advice->fa_prevstart;
  832                         else if (fp->f_advice->fa_prevstart != 0 &&
  833                             fp->f_advice->fa_prevstart == end + 1)
  834                                 end = fp->f_advice->fa_prevend;
  835                         fp->f_advice->fa_prevstart = start;
  836                         fp->f_advice->fa_prevend = end;
  837                 }
  838                 mtx_unlock(mtxp);
  839                 error = VOP_ADVISE(vp, start, end, POSIX_FADV_DONTNEED);
  840         }
  841         return (error);
  842 }
  843 
  844 /*
  845  * File table vnode write routine.
  846  */
  847 static int
  848 vn_write(fp, uio, active_cred, flags, td)
  849         struct file *fp;
  850         struct uio *uio;
  851         struct ucred *active_cred;
  852         int flags;
  853         struct thread *td;
  854 {
  855         struct vnode *vp;
  856         struct mount *mp;
  857         struct mtx *mtxp;
  858         int error, ioflag, lock_flags;
  859         int advice;
  860         off_t offset, start, end;
  861 
  862         KASSERT(uio->uio_td == td, ("uio_td %p is not td %p",
  863             uio->uio_td, td));
  864         KASSERT(flags & FOF_OFFSET, ("No FOF_OFFSET"));
  865         vp = fp->f_vnode;
  866         if (vp->v_type == VREG)
  867                 bwillwrite();
  868         ioflag = IO_UNIT;
  869         if (vp->v_type == VREG && (fp->f_flag & O_APPEND))
  870                 ioflag |= IO_APPEND;
  871         if (fp->f_flag & FNONBLOCK)
  872                 ioflag |= IO_NDELAY;
  873         if (fp->f_flag & O_DIRECT)
  874                 ioflag |= IO_DIRECT;
  875         if ((fp->f_flag & O_FSYNC) ||
  876             (vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS)))
  877                 ioflag |= IO_SYNC;
  878         mp = NULL;
  879         if (vp->v_type != VCHR &&
  880             (error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) != 0)
  881                 goto unlock;
  882 
  883         advice = get_advice(fp, uio);
  884 
  885         if (MNT_SHARED_WRITES(mp) ||
  886             (mp == NULL && MNT_SHARED_WRITES(vp->v_mount))) {
  887                 lock_flags = LK_SHARED;
  888         } else {
  889                 lock_flags = LK_EXCLUSIVE;
  890         }
  891 
  892         vn_lock(vp, lock_flags | LK_RETRY);
  893         switch (advice) {
  894         case POSIX_FADV_NORMAL:
  895         case POSIX_FADV_SEQUENTIAL:
  896         case POSIX_FADV_NOREUSE:
  897                 ioflag |= sequential_heuristic(uio, fp);
  898                 break;
  899         case POSIX_FADV_RANDOM:
  900                 /* XXX: Is this correct? */
  901                 break;
  902         }
  903         offset = uio->uio_offset;
  904 
  905 #ifdef MAC
  906         error = mac_vnode_check_write(active_cred, fp->f_cred, vp);
  907         if (error == 0)
  908 #endif
  909                 error = VOP_WRITE(vp, uio, ioflag, fp->f_cred);
  910         fp->f_nextoff = uio->uio_offset;
  911         VOP_UNLOCK(vp, 0);
  912         if (vp->v_type != VCHR)
  913                 vn_finished_write(mp);
  914         if (error == 0 && advice == POSIX_FADV_NOREUSE &&
  915             offset != uio->uio_offset) {
  916                 /*
  917                  * Use POSIX_FADV_DONTNEED to flush clean pages and
  918                  * buffers for the backing file after a
  919                  * POSIX_FADV_NOREUSE write(2).  To optimize the
  920                  * common case of using POSIX_FADV_NOREUSE with
  921                  * sequential access, track the previous implicit
  922                  * DONTNEED request and grow this request to include
  923                  * the current write(2) in addition to the previous
  924                  * DONTNEED.  With purely sequential access this will
  925                  * cause the DONTNEED requests to continously grow to
  926                  * cover all of the previously written regions of the
  927                  * file.
  928                  *
  929                  * Note that the blocks just written are almost
  930                  * certainly still dirty, so this only works when
  931                  * VOP_ADVISE() calls from subsequent writes push out
  932                  * the data written by this write(2) once the backing
  933                  * buffers are clean.  However, as compared to forcing
  934                  * IO_DIRECT, this gives much saner behavior.  Write
  935                  * clustering is still allowed, and clean pages are
  936                  * merely moved to the cache page queue rather than
  937                  * outright thrown away.  This means a subsequent
  938                  * read(2) can still avoid hitting the disk if the
  939                  * pages have not been reclaimed.
  940                  *
  941                  * This does make POSIX_FADV_NOREUSE largely useless
  942                  * with non-sequential access.  However, sequential
  943                  * access is the more common use case and the flag is
  944                  * merely advisory.
  945                  */
  946                 start = offset;
  947                 end = uio->uio_offset - 1;
  948                 mtxp = mtx_pool_find(mtxpool_sleep, fp);
  949                 mtx_lock(mtxp);
  950                 if (fp->f_advice != NULL &&
  951                     fp->f_advice->fa_advice == POSIX_FADV_NOREUSE) {
  952                         if (start != 0 && fp->f_advice->fa_prevend + 1 == start)
  953                                 start = fp->f_advice->fa_prevstart;
  954                         else if (fp->f_advice->fa_prevstart != 0 &&
  955                             fp->f_advice->fa_prevstart == end + 1)
  956                                 end = fp->f_advice->fa_prevend;
  957                         fp->f_advice->fa_prevstart = start;
  958                         fp->f_advice->fa_prevend = end;
  959                 }
  960                 mtx_unlock(mtxp);
  961                 error = VOP_ADVISE(vp, start, end, POSIX_FADV_DONTNEED);
  962         }
  963         
  964 unlock:
  965         return (error);
  966 }
  967 
  968 /*
  969  * The vn_io_fault() is a wrapper around vn_read() and vn_write() to
  970  * prevent the following deadlock:
  971  *
  972  * Assume that the thread A reads from the vnode vp1 into userspace
  973  * buffer buf1 backed by the pages of vnode vp2.  If a page in buf1 is
  974  * currently not resident, then system ends up with the call chain
  975  *   vn_read() -> VOP_READ(vp1) -> uiomove() -> [Page Fault] ->
  976  *     vm_fault(buf1) -> vnode_pager_getpages(vp2) -> VOP_GETPAGES(vp2)
  977  * which establishes lock order vp1->vn_lock, then vp2->vn_lock.
  978  * If, at the same time, thread B reads from vnode vp2 into buffer buf2
  979  * backed by the pages of vnode vp1, and some page in buf2 is not
  980  * resident, we get a reversed order vp2->vn_lock, then vp1->vn_lock.
  981  *
  982  * To prevent the lock order reversal and deadlock, vn_io_fault() does
  983  * not allow page faults to happen during VOP_READ() or VOP_WRITE().
  984  * Instead, it first tries to do the whole range i/o with pagefaults
  985  * disabled. If all pages in the i/o buffer are resident and mapped,
  986  * VOP will succeed (ignoring the genuine filesystem errors).
  987  * Otherwise, we get back EFAULT, and vn_io_fault() falls back to do
  988  * i/o in chunks, with all pages in the chunk prefaulted and held
  989  * using vm_fault_quick_hold_pages().
  990  *
  991  * Filesystems using this deadlock avoidance scheme should use the
  992  * array of the held pages from uio, saved in the curthread->td_ma,
  993  * instead of doing uiomove().  A helper function
  994  * vn_io_fault_uiomove() converts uiomove request into
  995  * uiomove_fromphys() over td_ma array.
  996  *
  997  * Since vnode locks do not cover the whole i/o anymore, rangelocks
  998  * make the current i/o request atomic with respect to other i/os and
  999  * truncations.
 1000  */
 1001 
 1002 /*
 1003  * Decode vn_io_fault_args and perform the corresponding i/o.
 1004  */
 1005 static int
 1006 vn_io_fault_doio(struct vn_io_fault_args *args, struct uio *uio,
 1007     struct thread *td)
 1008 {
 1009 
 1010         switch (args->kind) {
 1011         case VN_IO_FAULT_FOP:
 1012                 return ((args->args.fop_args.doio)(args->args.fop_args.fp,
 1013                     uio, args->cred, args->flags, td));
 1014         case VN_IO_FAULT_VOP:
 1015                 if (uio->uio_rw == UIO_READ) {
 1016                         return (VOP_READ(args->args.vop_args.vp, uio,
 1017                             args->flags, args->cred));
 1018                 } else if (uio->uio_rw == UIO_WRITE) {
 1019                         return (VOP_WRITE(args->args.vop_args.vp, uio,
 1020                             args->flags, args->cred));
 1021                 }
 1022                 break;
 1023         }
 1024         panic("vn_io_fault_doio: unknown kind of io %d %d", args->kind,
 1025             uio->uio_rw);
 1026 }
 1027 
 1028 static int
 1029 vn_io_fault_touch(char *base, const struct uio *uio)
 1030 {
 1031         int r;
 1032 
 1033         r = fubyte(base);
 1034         if (r == -1 || (uio->uio_rw == UIO_READ && subyte(base, r) == -1))
 1035                 return (EFAULT);
 1036         return (0);
 1037 }
 1038 
 1039 static int
 1040 vn_io_fault_prefault_user(const struct uio *uio)
 1041 {
 1042         char *base;
 1043         const struct iovec *iov;
 1044         size_t len;
 1045         ssize_t resid;
 1046         int error, i;
 1047 
 1048         KASSERT(uio->uio_segflg == UIO_USERSPACE,
 1049             ("vn_io_fault_prefault userspace"));
 1050 
 1051         error = i = 0;
 1052         iov = uio->uio_iov;
 1053         resid = uio->uio_resid;
 1054         base = iov->iov_base;
 1055         len = iov->iov_len;
 1056         while (resid > 0) {
 1057                 error = vn_io_fault_touch(base, uio);
 1058                 if (error != 0)
 1059                         break;
 1060                 if (len < PAGE_SIZE) {
 1061                         if (len != 0) {
 1062                                 error = vn_io_fault_touch(base + len - 1, uio);
 1063                                 if (error != 0)
 1064                                         break;
 1065                                 resid -= len;
 1066                         }
 1067                         if (++i >= uio->uio_iovcnt)
 1068                                 break;
 1069                         iov = uio->uio_iov + i;
 1070                         base = iov->iov_base;
 1071                         len = iov->iov_len;
 1072                 } else {
 1073                         len -= PAGE_SIZE;
 1074                         base += PAGE_SIZE;
 1075                         resid -= PAGE_SIZE;
 1076                 }
 1077         }
 1078         return (error);
 1079 }
 1080 
 1081 /*
 1082  * Common code for vn_io_fault(), agnostic to the kind of i/o request.
 1083  * Uses vn_io_fault_doio() to make the call to an actual i/o function.
 1084  * Used from vn_rdwr() and vn_io_fault(), which encode the i/o request
 1085  * into args and call vn_io_fault1() to handle faults during the user
 1086  * mode buffer accesses.
 1087  */
 1088 static int
 1089 vn_io_fault1(struct vnode *vp, struct uio *uio, struct vn_io_fault_args *args,
 1090     struct thread *td)
 1091 {
 1092         vm_page_t ma[io_hold_cnt + 2];
 1093         struct uio *uio_clone, short_uio;
 1094         struct iovec short_iovec[1];
 1095         vm_page_t *prev_td_ma;
 1096         vm_prot_t prot;
 1097         vm_offset_t addr, end;
 1098         size_t len, resid;
 1099         ssize_t adv;
 1100         int error, cnt, save, saveheld, prev_td_ma_cnt;
 1101 
 1102         if (vn_io_fault_prefault) {
 1103                 error = vn_io_fault_prefault_user(uio);
 1104                 if (error != 0)
 1105                         return (error); /* Or ignore ? */
 1106         }
 1107 
 1108         prot = uio->uio_rw == UIO_READ ? VM_PROT_WRITE : VM_PROT_READ;
 1109 
 1110         /*
 1111          * The UFS follows IO_UNIT directive and replays back both
 1112          * uio_offset and uio_resid if an error is encountered during the
 1113          * operation.  But, since the iovec may be already advanced,
 1114          * uio is still in an inconsistent state.
 1115          *
 1116          * Cache a copy of the original uio, which is advanced to the redo
 1117          * point using UIO_NOCOPY below.
 1118          */
 1119         uio_clone = cloneuio(uio);
 1120         resid = uio->uio_resid;
 1121 
 1122         short_uio.uio_segflg = UIO_USERSPACE;
 1123         short_uio.uio_rw = uio->uio_rw;
 1124         short_uio.uio_td = uio->uio_td;
 1125 
 1126         save = vm_fault_disable_pagefaults();
 1127         error = vn_io_fault_doio(args, uio, td);
 1128         if (error != EFAULT)
 1129                 goto out;
 1130 
 1131         atomic_add_long(&vn_io_faults_cnt, 1);
 1132         uio_clone->uio_segflg = UIO_NOCOPY;
 1133         uiomove(NULL, resid - uio->uio_resid, uio_clone);
 1134         uio_clone->uio_segflg = uio->uio_segflg;
 1135 
 1136         saveheld = curthread_pflags_set(TDP_UIOHELD);
 1137         prev_td_ma = td->td_ma;
 1138         prev_td_ma_cnt = td->td_ma_cnt;
 1139 
 1140         while (uio_clone->uio_resid != 0) {
 1141                 len = uio_clone->uio_iov->iov_len;
 1142                 if (len == 0) {
 1143                         KASSERT(uio_clone->uio_iovcnt >= 1,
 1144                             ("iovcnt underflow"));
 1145                         uio_clone->uio_iov++;
 1146                         uio_clone->uio_iovcnt--;
 1147                         continue;
 1148                 }
 1149                 if (len > io_hold_cnt * PAGE_SIZE)
 1150                         len = io_hold_cnt * PAGE_SIZE;
 1151                 addr = (uintptr_t)uio_clone->uio_iov->iov_base;
 1152                 end = round_page(addr + len);
 1153                 if (end < addr) {
 1154                         error = EFAULT;
 1155                         break;
 1156                 }
 1157                 cnt = atop(end - trunc_page(addr));
 1158                 /*
 1159                  * A perfectly misaligned address and length could cause
 1160                  * both the start and the end of the chunk to use partial
 1161                  * page.  +2 accounts for such a situation.
 1162                  */
 1163                 cnt = vm_fault_quick_hold_pages(&td->td_proc->p_vmspace->vm_map,
 1164                     addr, len, prot, ma, io_hold_cnt + 2);
 1165                 if (cnt == -1) {
 1166                         error = EFAULT;
 1167                         break;
 1168                 }
 1169                 short_uio.uio_iov = &short_iovec[0];
 1170                 short_iovec[0].iov_base = (void *)addr;
 1171                 short_uio.uio_iovcnt = 1;
 1172                 short_uio.uio_resid = short_iovec[0].iov_len = len;
 1173                 short_uio.uio_offset = uio_clone->uio_offset;
 1174                 td->td_ma = ma;
 1175                 td->td_ma_cnt = cnt;
 1176 
 1177                 error = vn_io_fault_doio(args, &short_uio, td);
 1178                 vm_page_unhold_pages(ma, cnt);
 1179                 adv = len - short_uio.uio_resid;
 1180 
 1181                 uio_clone->uio_iov->iov_base =
 1182                     (char *)uio_clone->uio_iov->iov_base + adv;
 1183                 uio_clone->uio_iov->iov_len -= adv;
 1184                 uio_clone->uio_resid -= adv;
 1185                 uio_clone->uio_offset += adv;
 1186 
 1187                 uio->uio_resid -= adv;
 1188                 uio->uio_offset += adv;
 1189 
 1190                 if (error != 0 || adv == 0)
 1191                         break;
 1192         }
 1193         td->td_ma = prev_td_ma;
 1194         td->td_ma_cnt = prev_td_ma_cnt;
 1195         curthread_pflags_restore(saveheld);
 1196 out:
 1197         vm_fault_enable_pagefaults(save);
 1198         free(uio_clone, M_IOV);
 1199         return (error);
 1200 }
 1201 
 1202 static int
 1203 vn_io_fault(struct file *fp, struct uio *uio, struct ucred *active_cred,
 1204     int flags, struct thread *td)
 1205 {
 1206         fo_rdwr_t *doio;
 1207         struct vnode *vp;
 1208         void *rl_cookie;
 1209         struct vn_io_fault_args args;
 1210         int error;
 1211 
 1212         doio = uio->uio_rw == UIO_READ ? vn_read : vn_write;
 1213         vp = fp->f_vnode;
 1214         foffset_lock_uio(fp, uio, flags);
 1215         if (do_vn_io_fault(vp, uio)) {
 1216                 args.kind = VN_IO_FAULT_FOP;
 1217                 args.args.fop_args.fp = fp;
 1218                 args.args.fop_args.doio = doio;
 1219                 args.cred = active_cred;
 1220                 args.flags = flags | FOF_OFFSET;
 1221                 if (uio->uio_rw == UIO_READ) {
 1222                         rl_cookie = vn_rangelock_rlock(vp, uio->uio_offset,
 1223                             uio->uio_offset + uio->uio_resid);
 1224                 } else if ((fp->f_flag & O_APPEND) != 0 ||
 1225                     (flags & FOF_OFFSET) == 0) {
 1226                         /* For appenders, punt and lock the whole range. */
 1227                         rl_cookie = vn_rangelock_wlock(vp, 0, OFF_MAX);
 1228                 } else {
 1229                         rl_cookie = vn_rangelock_wlock(vp, uio->uio_offset,
 1230                             uio->uio_offset + uio->uio_resid);
 1231                 }
 1232                 error = vn_io_fault1(vp, uio, &args, td);
 1233                 vn_rangelock_unlock(vp, rl_cookie);
 1234         } else {
 1235                 error = doio(fp, uio, active_cred, flags | FOF_OFFSET, td);
 1236         }
 1237         foffset_unlock_uio(fp, uio, flags);
 1238         return (error);
 1239 }
 1240 
 1241 /*
 1242  * Helper function to perform the requested uiomove operation using
 1243  * the held pages for io->uio_iov[0].iov_base buffer instead of
 1244  * copyin/copyout.  Access to the pages with uiomove_fromphys()
 1245  * instead of iov_base prevents page faults that could occur due to
 1246  * pmap_collect() invalidating the mapping created by
 1247  * vm_fault_quick_hold_pages(), or pageout daemon, page laundry or
 1248  * object cleanup revoking the write access from page mappings.
 1249  *
 1250  * Filesystems specified MNTK_NO_IOPF shall use vn_io_fault_uiomove()
 1251  * instead of plain uiomove().
 1252  */
 1253 int
 1254 vn_io_fault_uiomove(char *data, int xfersize, struct uio *uio)
 1255 {
 1256         struct uio transp_uio;
 1257         struct iovec transp_iov[1];
 1258         struct thread *td;
 1259         size_t adv;
 1260         int error, pgadv;
 1261 
 1262         td = curthread;
 1263         if ((td->td_pflags & TDP_UIOHELD) == 0 ||
 1264             uio->uio_segflg != UIO_USERSPACE)
 1265                 return (uiomove(data, xfersize, uio));
 1266 
 1267         KASSERT(uio->uio_iovcnt == 1, ("uio_iovcnt %d", uio->uio_iovcnt));
 1268         transp_iov[0].iov_base = data;
 1269         transp_uio.uio_iov = &transp_iov[0];
 1270         transp_uio.uio_iovcnt = 1;
 1271         if (xfersize > uio->uio_resid)
 1272                 xfersize = uio->uio_resid;
 1273         transp_uio.uio_resid = transp_iov[0].iov_len = xfersize;
 1274         transp_uio.uio_offset = 0;
 1275         transp_uio.uio_segflg = UIO_SYSSPACE;
 1276         /*
 1277          * Since transp_iov points to data, and td_ma page array
 1278          * corresponds to original uio->uio_iov, we need to invert the
 1279          * direction of the i/o operation as passed to
 1280          * uiomove_fromphys().
 1281          */
 1282         switch (uio->uio_rw) {
 1283         case UIO_WRITE:
 1284                 transp_uio.uio_rw = UIO_READ;
 1285                 break;
 1286         case UIO_READ:
 1287                 transp_uio.uio_rw = UIO_WRITE;
 1288                 break;
 1289         }
 1290         transp_uio.uio_td = uio->uio_td;
 1291         error = uiomove_fromphys(td->td_ma,
 1292             ((vm_offset_t)uio->uio_iov->iov_base) & PAGE_MASK,
 1293             xfersize, &transp_uio);
 1294         adv = xfersize - transp_uio.uio_resid;
 1295         pgadv =
 1296             (((vm_offset_t)uio->uio_iov->iov_base + adv) >> PAGE_SHIFT) -
 1297             (((vm_offset_t)uio->uio_iov->iov_base) >> PAGE_SHIFT);
 1298         td->td_ma += pgadv;
 1299         KASSERT(td->td_ma_cnt >= pgadv, ("consumed pages %d %d", td->td_ma_cnt,
 1300             pgadv));
 1301         td->td_ma_cnt -= pgadv;
 1302         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + adv;
 1303         uio->uio_iov->iov_len -= adv;
 1304         uio->uio_resid -= adv;
 1305         uio->uio_offset += adv;
 1306         return (error);
 1307 }
 1308 
 1309 int
 1310 vn_io_fault_pgmove(vm_page_t ma[], vm_offset_t offset, int xfersize,
 1311     struct uio *uio)
 1312 {
 1313         struct thread *td;
 1314         vm_offset_t iov_base;
 1315         int cnt, pgadv;
 1316 
 1317         td = curthread;
 1318         if ((td->td_pflags & TDP_UIOHELD) == 0 ||
 1319             uio->uio_segflg != UIO_USERSPACE)
 1320                 return (uiomove_fromphys(ma, offset, xfersize, uio));
 1321 
 1322         KASSERT(uio->uio_iovcnt == 1, ("uio_iovcnt %d", uio->uio_iovcnt));
 1323         cnt = xfersize > uio->uio_resid ? uio->uio_resid : xfersize;
 1324         iov_base = (vm_offset_t)uio->uio_iov->iov_base;
 1325         switch (uio->uio_rw) {
 1326         case UIO_WRITE:
 1327                 pmap_copy_pages(td->td_ma, iov_base & PAGE_MASK, ma,
 1328                     offset, cnt);
 1329                 break;
 1330         case UIO_READ:
 1331                 pmap_copy_pages(ma, offset, td->td_ma, iov_base & PAGE_MASK,
 1332                     cnt);
 1333                 break;
 1334         }
 1335         pgadv = ((iov_base + cnt) >> PAGE_SHIFT) - (iov_base >> PAGE_SHIFT);
 1336         td->td_ma += pgadv;
 1337         KASSERT(td->td_ma_cnt >= pgadv, ("consumed pages %d %d", td->td_ma_cnt,
 1338             pgadv));
 1339         td->td_ma_cnt -= pgadv;
 1340         uio->uio_iov->iov_base = (char *)(iov_base + cnt);
 1341         uio->uio_iov->iov_len -= cnt;
 1342         uio->uio_resid -= cnt;
 1343         uio->uio_offset += cnt;
 1344         return (0);
 1345 }
 1346 
 1347 
 1348 /*
 1349  * File table truncate routine.
 1350  */
 1351 static int
 1352 vn_truncate(struct file *fp, off_t length, struct ucred *active_cred,
 1353     struct thread *td)
 1354 {
 1355         struct vattr vattr;
 1356         struct mount *mp;
 1357         struct vnode *vp;
 1358         void *rl_cookie;
 1359         int error;
 1360 
 1361         vp = fp->f_vnode;
 1362 
 1363         /*
 1364          * Lock the whole range for truncation.  Otherwise split i/o
 1365          * might happen partly before and partly after the truncation.
 1366          */
 1367         rl_cookie = vn_rangelock_wlock(vp, 0, OFF_MAX);
 1368         error = vn_start_write(vp, &mp, V_WAIT | PCATCH);
 1369         if (error)
 1370                 goto out1;
 1371         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 1372         if (vp->v_type == VDIR) {
 1373                 error = EISDIR;
 1374                 goto out;
 1375         }
 1376 #ifdef MAC
 1377         error = mac_vnode_check_write(active_cred, fp->f_cred, vp);
 1378         if (error)
 1379                 goto out;
 1380 #endif
 1381         error = vn_writechk(vp);
 1382         if (error == 0) {
 1383                 VATTR_NULL(&vattr);
 1384                 vattr.va_size = length;
 1385                 if ((fp->f_flag & O_FSYNC) != 0)
 1386                         vattr.va_vaflags |= VA_SYNC;
 1387                 error = VOP_SETATTR(vp, &vattr, fp->f_cred);
 1388         }
 1389 out:
 1390         VOP_UNLOCK(vp, 0);
 1391         vn_finished_write(mp);
 1392 out1:
 1393         vn_rangelock_unlock(vp, rl_cookie);
 1394         return (error);
 1395 }
 1396 
 1397 /*
 1398  * File table vnode stat routine.
 1399  */
 1400 static int
 1401 vn_statfile(fp, sb, active_cred, td)
 1402         struct file *fp;
 1403         struct stat *sb;
 1404         struct ucred *active_cred;
 1405         struct thread *td;
 1406 {
 1407         struct vnode *vp = fp->f_vnode;
 1408         int error;
 1409 
 1410         vn_lock(vp, LK_SHARED | LK_RETRY);
 1411         error = vn_stat(vp, sb, active_cred, fp->f_cred, td);
 1412         VOP_UNLOCK(vp, 0);
 1413 
 1414         return (error);
 1415 }
 1416 
 1417 /*
 1418  * Stat a vnode; implementation for the stat syscall
 1419  */
 1420 int
 1421 vn_stat(vp, sb, active_cred, file_cred, td)
 1422         struct vnode *vp;
 1423         register struct stat *sb;
 1424         struct ucred *active_cred;
 1425         struct ucred *file_cred;
 1426         struct thread *td;
 1427 {
 1428         struct vattr vattr;
 1429         register struct vattr *vap;
 1430         int error;
 1431         u_short mode;
 1432 
 1433 #ifdef MAC
 1434         error = mac_vnode_check_stat(active_cred, file_cred, vp);
 1435         if (error)
 1436                 return (error);
 1437 #endif
 1438 
 1439         vap = &vattr;
 1440 
 1441         /*
 1442          * Initialize defaults for new and unusual fields, so that file
 1443          * systems which don't support these fields don't need to know
 1444          * about them.
 1445          */
 1446         vap->va_birthtime.tv_sec = -1;
 1447         vap->va_birthtime.tv_nsec = 0;
 1448         vap->va_fsid = VNOVAL;
 1449         vap->va_rdev = NODEV;
 1450 
 1451         error = VOP_GETATTR(vp, vap, active_cred);
 1452         if (error)
 1453                 return (error);
 1454 
 1455         /*
 1456          * Zero the spare stat fields
 1457          */
 1458         bzero(sb, sizeof *sb);
 1459 
 1460         /*
 1461          * Copy from vattr table
 1462          */
 1463         if (vap->va_fsid != VNOVAL)
 1464                 sb->st_dev = vap->va_fsid;
 1465         else
 1466                 sb->st_dev = vp->v_mount->mnt_stat.f_fsid.val[0];
 1467         sb->st_ino = vap->va_fileid;
 1468         mode = vap->va_mode;
 1469         switch (vap->va_type) {
 1470         case VREG:
 1471                 mode |= S_IFREG;
 1472                 break;
 1473         case VDIR:
 1474                 mode |= S_IFDIR;
 1475                 break;
 1476         case VBLK:
 1477                 mode |= S_IFBLK;
 1478                 break;
 1479         case VCHR:
 1480                 mode |= S_IFCHR;
 1481                 break;
 1482         case VLNK:
 1483                 mode |= S_IFLNK;
 1484                 break;
 1485         case VSOCK:
 1486                 mode |= S_IFSOCK;
 1487                 break;
 1488         case VFIFO:
 1489                 mode |= S_IFIFO;
 1490                 break;
 1491         default:
 1492                 return (EBADF);
 1493         };
 1494         sb->st_mode = mode;
 1495         sb->st_nlink = vap->va_nlink;
 1496         sb->st_uid = vap->va_uid;
 1497         sb->st_gid = vap->va_gid;
 1498         sb->st_rdev = vap->va_rdev;
 1499         if (vap->va_size > OFF_MAX)
 1500                 return (EOVERFLOW);
 1501         sb->st_size = vap->va_size;
 1502         sb->st_atim = vap->va_atime;
 1503         sb->st_mtim = vap->va_mtime;
 1504         sb->st_ctim = vap->va_ctime;
 1505         sb->st_birthtim = vap->va_birthtime;
 1506 
 1507         /*
 1508          * According to www.opengroup.org, the meaning of st_blksize is 
 1509          *   "a filesystem-specific preferred I/O block size for this 
 1510          *    object.  In some filesystem types, this may vary from file
 1511          *    to file"
 1512          * Use miminum/default of PAGE_SIZE (e.g. for VCHR).
 1513          */
 1514 
 1515         sb->st_blksize = max(PAGE_SIZE, vap->va_blocksize);
 1516         
 1517         sb->st_flags = vap->va_flags;
 1518         if (priv_check(td, PRIV_VFS_GENERATION))
 1519                 sb->st_gen = 0;
 1520         else
 1521                 sb->st_gen = vap->va_gen;
 1522 
 1523         sb->st_blocks = vap->va_bytes / S_BLKSIZE;
 1524         return (0);
 1525 }
 1526 
 1527 /*
 1528  * File table vnode ioctl routine.
 1529  */
 1530 static int
 1531 vn_ioctl(fp, com, data, active_cred, td)
 1532         struct file *fp;
 1533         u_long com;
 1534         void *data;
 1535         struct ucred *active_cred;
 1536         struct thread *td;
 1537 {
 1538         struct vattr vattr;
 1539         struct vnode *vp;
 1540         int error;
 1541 
 1542         vp = fp->f_vnode;
 1543         switch (vp->v_type) {
 1544         case VDIR:
 1545         case VREG:
 1546                 switch (com) {
 1547                 case FIONREAD:
 1548                         vn_lock(vp, LK_SHARED | LK_RETRY);
 1549                         error = VOP_GETATTR(vp, &vattr, active_cred);
 1550                         VOP_UNLOCK(vp, 0);
 1551                         if (error == 0)
 1552                                 *(int *)data = vattr.va_size - fp->f_offset;
 1553                         return (error);
 1554                 case FIONBIO:
 1555                 case FIOASYNC:
 1556                         return (0);
 1557                 default:
 1558                         return (VOP_IOCTL(vp, com, data, fp->f_flag,
 1559                             active_cred, td));
 1560                 }
 1561         default:
 1562                 return (ENOTTY);
 1563         }
 1564 }
 1565 
 1566 /*
 1567  * File table vnode poll routine.
 1568  */
 1569 static int
 1570 vn_poll(fp, events, active_cred, td)
 1571         struct file *fp;
 1572         int events;
 1573         struct ucred *active_cred;
 1574         struct thread *td;
 1575 {
 1576         struct vnode *vp;
 1577         int error;
 1578 
 1579         vp = fp->f_vnode;
 1580 #ifdef MAC
 1581         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 1582         error = mac_vnode_check_poll(active_cred, fp->f_cred, vp);
 1583         VOP_UNLOCK(vp, 0);
 1584         if (!error)
 1585 #endif
 1586 
 1587         error = VOP_POLL(vp, events, fp->f_cred, td);
 1588         return (error);
 1589 }
 1590 
 1591 /*
 1592  * Acquire the requested lock and then check for validity.  LK_RETRY
 1593  * permits vn_lock to return doomed vnodes.
 1594  */
 1595 int
 1596 _vn_lock(struct vnode *vp, int flags, char *file, int line)
 1597 {
 1598         int error;
 1599 
 1600         VNASSERT((flags & LK_TYPE_MASK) != 0, vp,
 1601             ("vn_lock called with no locktype."));
 1602         do {
 1603 #ifdef DEBUG_VFS_LOCKS
 1604                 KASSERT(vp->v_holdcnt != 0,
 1605                     ("vn_lock %p: zero hold count", vp));
 1606 #endif
 1607                 error = VOP_LOCK1(vp, flags, file, line);
 1608                 flags &= ~LK_INTERLOCK; /* Interlock is always dropped. */
 1609                 KASSERT((flags & LK_RETRY) == 0 || error == 0,
 1610                     ("LK_RETRY set with incompatible flags (0x%x) or an error occurred (%d)",
 1611                     flags, error));
 1612                 /*
 1613                  * Callers specify LK_RETRY if they wish to get dead vnodes.
 1614                  * If RETRY is not set, we return ENOENT instead.
 1615                  */
 1616                 if (error == 0 && vp->v_iflag & VI_DOOMED &&
 1617                     (flags & LK_RETRY) == 0) {
 1618                         VOP_UNLOCK(vp, 0);
 1619                         error = ENOENT;
 1620                         break;
 1621                 }
 1622         } while (flags & LK_RETRY && error != 0);
 1623         return (error);
 1624 }
 1625 
 1626 /*
 1627  * File table vnode close routine.
 1628  */
 1629 static int
 1630 vn_closefile(fp, td)
 1631         struct file *fp;
 1632         struct thread *td;
 1633 {
 1634         struct vnode *vp;
 1635         struct flock lf;
 1636         int error;
 1637         bool ref;
 1638 
 1639         vp = fp->f_vnode;
 1640         fp->f_ops = &badfileops;
 1641         ref= (fp->f_flag & FHASLOCK) != 0 && fp->f_type == DTYPE_VNODE;
 1642 
 1643         error = vn_close1(vp, fp->f_flag, fp->f_cred, td, ref);
 1644 
 1645         if (__predict_false(ref)) {
 1646                 lf.l_whence = SEEK_SET;
 1647                 lf.l_start = 0;
 1648                 lf.l_len = 0;
 1649                 lf.l_type = F_UNLCK;
 1650                 (void) VOP_ADVLOCK(vp, fp, F_UNLCK, &lf, F_FLOCK);
 1651                 vrele(vp);
 1652         }
 1653         return (error);
 1654 }
 1655 
 1656 /*
 1657  * Preparing to start a filesystem write operation. If the operation is
 1658  * permitted, then we bump the count of operations in progress and
 1659  * proceed. If a suspend request is in progress, we wait until the
 1660  * suspension is over, and then proceed.
 1661  */
 1662 static int
 1663 vn_start_write_locked(struct mount *mp, int flags)
 1664 {
 1665         int error, mflags;
 1666 
 1667         mtx_assert(MNT_MTX(mp), MA_OWNED);
 1668         error = 0;
 1669 
 1670         /*
 1671          * Check on status of suspension.
 1672          */
 1673         if ((curthread->td_pflags & TDP_IGNSUSP) == 0 ||
 1674             mp->mnt_susp_owner != curthread) {
 1675                 mflags = ((mp->mnt_vfc->vfc_flags & VFCF_SBDRY) != 0 ?
 1676                     (flags & PCATCH) : 0) | (PUSER - 1);
 1677                 while ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0) {
 1678                         if (flags & V_NOWAIT) {
 1679                                 error = EWOULDBLOCK;
 1680                                 goto unlock;
 1681                         }
 1682                         error = msleep(&mp->mnt_flag, MNT_MTX(mp), mflags,
 1683                             "suspfs", 0);
 1684                         if (error)
 1685                                 goto unlock;
 1686                 }
 1687         }
 1688         if (flags & V_XSLEEP)
 1689                 goto unlock;
 1690         mp->mnt_writeopcount++;
 1691 unlock:
 1692         if (error != 0 || (flags & V_XSLEEP) != 0)
 1693                 MNT_REL(mp);
 1694         MNT_IUNLOCK(mp);
 1695         return (error);
 1696 }
 1697 
 1698 int
 1699 vn_start_write(struct vnode *vp, struct mount **mpp, int flags)
 1700 {
 1701         struct mount *mp;
 1702         int error;
 1703 
 1704         KASSERT((flags & V_MNTREF) == 0 || (*mpp != NULL && vp == NULL),
 1705             ("V_MNTREF requires mp"));
 1706 
 1707         error = 0;
 1708         /*
 1709          * If a vnode is provided, get and return the mount point that
 1710          * to which it will write.
 1711          */
 1712         if (vp != NULL) {
 1713                 if ((error = VOP_GETWRITEMOUNT(vp, mpp)) != 0) {
 1714                         *mpp = NULL;
 1715                         if (error != EOPNOTSUPP)
 1716                                 return (error);
 1717                         return (0);
 1718                 }
 1719         }
 1720         if ((mp = *mpp) == NULL)
 1721                 return (0);
 1722 
 1723         /*
 1724          * VOP_GETWRITEMOUNT() returns with the mp refcount held through
 1725          * a vfs_ref().
 1726          * As long as a vnode is not provided we need to acquire a
 1727          * refcount for the provided mountpoint too, in order to
 1728          * emulate a vfs_ref().
 1729          */
 1730         MNT_ILOCK(mp);
 1731         if (vp == NULL && (flags & V_MNTREF) == 0)
 1732                 MNT_REF(mp);
 1733 
 1734         return (vn_start_write_locked(mp, flags));
 1735 }
 1736 
 1737 /*
 1738  * Secondary suspension. Used by operations such as vop_inactive
 1739  * routines that are needed by the higher level functions. These
 1740  * are allowed to proceed until all the higher level functions have
 1741  * completed (indicated by mnt_writeopcount dropping to zero). At that
 1742  * time, these operations are halted until the suspension is over.
 1743  */
 1744 int
 1745 vn_start_secondary_write(struct vnode *vp, struct mount **mpp, int flags)
 1746 {
 1747         struct mount *mp;
 1748         int error;
 1749 
 1750         KASSERT((flags & V_MNTREF) == 0 || (*mpp != NULL && vp == NULL),
 1751             ("V_MNTREF requires mp"));
 1752 
 1753  retry:
 1754         if (vp != NULL) {
 1755                 if ((error = VOP_GETWRITEMOUNT(vp, mpp)) != 0) {
 1756                         *mpp = NULL;
 1757                         if (error != EOPNOTSUPP)
 1758                                 return (error);
 1759                         return (0);
 1760                 }
 1761         }
 1762         /*
 1763          * If we are not suspended or have not yet reached suspended
 1764          * mode, then let the operation proceed.
 1765          */
 1766         if ((mp = *mpp) == NULL)
 1767                 return (0);
 1768 
 1769         /*
 1770          * VOP_GETWRITEMOUNT() returns with the mp refcount held through
 1771          * a vfs_ref().
 1772          * As long as a vnode is not provided we need to acquire a
 1773          * refcount for the provided mountpoint too, in order to
 1774          * emulate a vfs_ref().
 1775          */
 1776         MNT_ILOCK(mp);
 1777         if (vp == NULL && (flags & V_MNTREF) == 0)
 1778                 MNT_REF(mp);
 1779         if ((mp->mnt_kern_flag & (MNTK_SUSPENDED | MNTK_SUSPEND2)) == 0) {
 1780                 mp->mnt_secondary_writes++;
 1781                 mp->mnt_secondary_accwrites++;
 1782                 MNT_IUNLOCK(mp);
 1783                 return (0);
 1784         }
 1785         if (flags & V_NOWAIT) {
 1786                 MNT_REL(mp);
 1787                 MNT_IUNLOCK(mp);
 1788                 return (EWOULDBLOCK);
 1789         }
 1790         /*
 1791          * Wait for the suspension to finish.
 1792          */
 1793         error = msleep(&mp->mnt_flag, MNT_MTX(mp), (PUSER - 1) | PDROP |
 1794             ((mp->mnt_vfc->vfc_flags & VFCF_SBDRY) != 0 ? (flags & PCATCH) : 0),
 1795             "suspfs", 0);
 1796         vfs_rel(mp);
 1797         if (error == 0)
 1798                 goto retry;
 1799         return (error);
 1800 }
 1801 
 1802 /*
 1803  * Filesystem write operation has completed. If we are suspending and this
 1804  * operation is the last one, notify the suspender that the suspension is
 1805  * now in effect.
 1806  */
 1807 void
 1808 vn_finished_write(mp)
 1809         struct mount *mp;
 1810 {
 1811         if (mp == NULL)
 1812                 return;
 1813         MNT_ILOCK(mp);
 1814         MNT_REL(mp);
 1815         mp->mnt_writeopcount--;
 1816         if (mp->mnt_writeopcount < 0)
 1817                 panic("vn_finished_write: neg cnt");
 1818         if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0 &&
 1819             mp->mnt_writeopcount <= 0)
 1820                 wakeup(&mp->mnt_writeopcount);
 1821         MNT_IUNLOCK(mp);
 1822 }
 1823 
 1824 
 1825 /*
 1826  * Filesystem secondary write operation has completed. If we are
 1827  * suspending and this operation is the last one, notify the suspender
 1828  * that the suspension is now in effect.
 1829  */
 1830 void
 1831 vn_finished_secondary_write(mp)
 1832         struct mount *mp;
 1833 {
 1834         if (mp == NULL)
 1835                 return;
 1836         MNT_ILOCK(mp);
 1837         MNT_REL(mp);
 1838         mp->mnt_secondary_writes--;
 1839         if (mp->mnt_secondary_writes < 0)
 1840                 panic("vn_finished_secondary_write: neg cnt");
 1841         if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0 &&
 1842             mp->mnt_secondary_writes <= 0)
 1843                 wakeup(&mp->mnt_secondary_writes);
 1844         MNT_IUNLOCK(mp);
 1845 }
 1846 
 1847 
 1848 
 1849 /*
 1850  * Request a filesystem to suspend write operations.
 1851  */
 1852 int
 1853 vfs_write_suspend(struct mount *mp, int flags)
 1854 {
 1855         int error;
 1856 
 1857         MNT_ILOCK(mp);
 1858         if (mp->mnt_susp_owner == curthread) {
 1859                 MNT_IUNLOCK(mp);
 1860                 return (EALREADY);
 1861         }
 1862         while (mp->mnt_kern_flag & MNTK_SUSPEND)
 1863                 msleep(&mp->mnt_flag, MNT_MTX(mp), PUSER - 1, "wsuspfs", 0);
 1864 
 1865         /*
 1866          * Unmount holds a write reference on the mount point.  If we
 1867          * own busy reference and drain for writers, we deadlock with
 1868          * the reference draining in the unmount path.  Callers of
 1869          * vfs_write_suspend() must specify VS_SKIP_UNMOUNT if
 1870          * vfs_busy() reference is owned and caller is not in the
 1871          * unmount context.
 1872          */
 1873         if ((flags & VS_SKIP_UNMOUNT) != 0 &&
 1874             (mp->mnt_kern_flag & MNTK_UNMOUNT) != 0) {
 1875                 MNT_IUNLOCK(mp);
 1876                 return (EBUSY);
 1877         }
 1878 
 1879         mp->mnt_kern_flag |= MNTK_SUSPEND;
 1880         mp->mnt_susp_owner = curthread;
 1881         if (mp->mnt_writeopcount > 0)
 1882                 (void) msleep(&mp->mnt_writeopcount, 
 1883                     MNT_MTX(mp), (PUSER - 1)|PDROP, "suspwt", 0);
 1884         else
 1885                 MNT_IUNLOCK(mp);
 1886         if ((error = VFS_SYNC(mp, MNT_SUSPEND)) != 0)
 1887                 vfs_write_resume(mp, 0);
 1888         return (error);
 1889 }
 1890 
 1891 /*
 1892  * Request a filesystem to resume write operations.
 1893  */
 1894 void
 1895 vfs_write_resume(struct mount *mp, int flags)
 1896 {
 1897 
 1898         MNT_ILOCK(mp);
 1899         if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0) {
 1900                 KASSERT(mp->mnt_susp_owner == curthread, ("mnt_susp_owner"));
 1901                 mp->mnt_kern_flag &= ~(MNTK_SUSPEND | MNTK_SUSPEND2 |
 1902                                        MNTK_SUSPENDED);
 1903                 mp->mnt_susp_owner = NULL;
 1904                 wakeup(&mp->mnt_writeopcount);
 1905                 wakeup(&mp->mnt_flag);
 1906                 curthread->td_pflags &= ~TDP_IGNSUSP;
 1907                 if ((flags & VR_START_WRITE) != 0) {
 1908                         MNT_REF(mp);
 1909                         mp->mnt_writeopcount++;
 1910                 }
 1911                 MNT_IUNLOCK(mp);
 1912                 if ((flags & VR_NO_SUSPCLR) == 0)
 1913                         VFS_SUSP_CLEAN(mp);
 1914         } else if ((flags & VR_START_WRITE) != 0) {
 1915                 MNT_REF(mp);
 1916                 vn_start_write_locked(mp, 0);
 1917         } else {
 1918                 MNT_IUNLOCK(mp);
 1919         }
 1920 }
 1921 
 1922 /*
 1923  * Helper loop around vfs_write_suspend() for filesystem unmount VFS
 1924  * methods.
 1925  */
 1926 int
 1927 vfs_write_suspend_umnt(struct mount *mp)
 1928 {
 1929         int error;
 1930 
 1931         KASSERT((curthread->td_pflags & TDP_IGNSUSP) == 0,
 1932             ("vfs_write_suspend_umnt: recursed"));
 1933 
 1934         /* dounmount() already called vn_start_write(). */
 1935         for (;;) {
 1936                 vn_finished_write(mp);
 1937                 error = vfs_write_suspend(mp, 0);
 1938                 if (error != 0) {
 1939                         vn_start_write(NULL, &mp, V_WAIT);
 1940                         return (error);
 1941                 }
 1942                 MNT_ILOCK(mp);
 1943                 if ((mp->mnt_kern_flag & MNTK_SUSPENDED) != 0)
 1944                         break;
 1945                 MNT_IUNLOCK(mp);
 1946                 vn_start_write(NULL, &mp, V_WAIT);
 1947         }
 1948         mp->mnt_kern_flag &= ~(MNTK_SUSPENDED | MNTK_SUSPEND2);
 1949         wakeup(&mp->mnt_flag);
 1950         MNT_IUNLOCK(mp);
 1951         curthread->td_pflags |= TDP_IGNSUSP;
 1952         return (0);
 1953 }
 1954 
 1955 /*
 1956  * Implement kqueues for files by translating it to vnode operation.
 1957  */
 1958 static int
 1959 vn_kqfilter(struct file *fp, struct knote *kn)
 1960 {
 1961 
 1962         return (VOP_KQFILTER(fp->f_vnode, kn));
 1963 }
 1964 
 1965 /*
 1966  * Simplified in-kernel wrapper calls for extended attribute access.
 1967  * Both calls pass in a NULL credential, authorizing as "kernel" access.
 1968  * Set IO_NODELOCKED in ioflg if the vnode is already locked.
 1969  */
 1970 int
 1971 vn_extattr_get(struct vnode *vp, int ioflg, int attrnamespace,
 1972     const char *attrname, int *buflen, char *buf, struct thread *td)
 1973 {
 1974         struct uio      auio;
 1975         struct iovec    iov;
 1976         int     error;
 1977 
 1978         iov.iov_len = *buflen;
 1979         iov.iov_base = buf;
 1980 
 1981         auio.uio_iov = &iov;
 1982         auio.uio_iovcnt = 1;
 1983         auio.uio_rw = UIO_READ;
 1984         auio.uio_segflg = UIO_SYSSPACE;
 1985         auio.uio_td = td;
 1986         auio.uio_offset = 0;
 1987         auio.uio_resid = *buflen;
 1988 
 1989         if ((ioflg & IO_NODELOCKED) == 0)
 1990                 vn_lock(vp, LK_SHARED | LK_RETRY);
 1991 
 1992         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
 1993 
 1994         /* authorize attribute retrieval as kernel */
 1995         error = VOP_GETEXTATTR(vp, attrnamespace, attrname, &auio, NULL, NULL,
 1996             td);
 1997 
 1998         if ((ioflg & IO_NODELOCKED) == 0)
 1999                 VOP_UNLOCK(vp, 0);
 2000 
 2001         if (error == 0) {
 2002                 *buflen = *buflen - auio.uio_resid;
 2003         }
 2004 
 2005         return (error);
 2006 }
 2007 
 2008 /*
 2009  * XXX failure mode if partially written?
 2010  */
 2011 int
 2012 vn_extattr_set(struct vnode *vp, int ioflg, int attrnamespace,
 2013     const char *attrname, int buflen, char *buf, struct thread *td)
 2014 {
 2015         struct uio      auio;
 2016         struct iovec    iov;
 2017         struct mount    *mp;
 2018         int     error;
 2019 
 2020         iov.iov_len = buflen;
 2021         iov.iov_base = buf;
 2022 
 2023         auio.uio_iov = &iov;
 2024         auio.uio_iovcnt = 1;
 2025         auio.uio_rw = UIO_WRITE;
 2026         auio.uio_segflg = UIO_SYSSPACE;
 2027         auio.uio_td = td;
 2028         auio.uio_offset = 0;
 2029         auio.uio_resid = buflen;
 2030 
 2031         if ((ioflg & IO_NODELOCKED) == 0) {
 2032                 if ((error = vn_start_write(vp, &mp, V_WAIT)) != 0)
 2033                         return (error);
 2034                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 2035         }
 2036 
 2037         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
 2038 
 2039         /* authorize attribute setting as kernel */
 2040         error = VOP_SETEXTATTR(vp, attrnamespace, attrname, &auio, NULL, td);
 2041 
 2042         if ((ioflg & IO_NODELOCKED) == 0) {
 2043                 vn_finished_write(mp);
 2044                 VOP_UNLOCK(vp, 0);
 2045         }
 2046 
 2047         return (error);
 2048 }
 2049 
 2050 int
 2051 vn_extattr_rm(struct vnode *vp, int ioflg, int attrnamespace,
 2052     const char *attrname, struct thread *td)
 2053 {
 2054         struct mount    *mp;
 2055         int     error;
 2056 
 2057         if ((ioflg & IO_NODELOCKED) == 0) {
 2058                 if ((error = vn_start_write(vp, &mp, V_WAIT)) != 0)
 2059                         return (error);
 2060                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 2061         }
 2062 
 2063         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
 2064 
 2065         /* authorize attribute removal as kernel */
 2066         error = VOP_DELETEEXTATTR(vp, attrnamespace, attrname, NULL, td);
 2067         if (error == EOPNOTSUPP)
 2068                 error = VOP_SETEXTATTR(vp, attrnamespace, attrname, NULL,
 2069                     NULL, td);
 2070 
 2071         if ((ioflg & IO_NODELOCKED) == 0) {
 2072                 vn_finished_write(mp);
 2073                 VOP_UNLOCK(vp, 0);
 2074         }
 2075 
 2076         return (error);
 2077 }
 2078 
 2079 static int
 2080 vn_get_ino_alloc_vget(struct mount *mp, void *arg, int lkflags,
 2081     struct vnode **rvp)
 2082 {
 2083 
 2084         return (VFS_VGET(mp, *(ino_t *)arg, lkflags, rvp));
 2085 }
 2086 
 2087 int
 2088 vn_vget_ino(struct vnode *vp, ino_t ino, int lkflags, struct vnode **rvp)
 2089 {
 2090 
 2091         return (vn_vget_ino_gen(vp, vn_get_ino_alloc_vget, &ino,
 2092             lkflags, rvp));
 2093 }
 2094 
 2095 int
 2096 vn_vget_ino_gen(struct vnode *vp, vn_get_ino_t alloc, void *alloc_arg,
 2097     int lkflags, struct vnode **rvp)
 2098 {
 2099         struct mount *mp;
 2100         int ltype, error;
 2101 
 2102         ASSERT_VOP_LOCKED(vp, "vn_vget_ino_get");
 2103         mp = vp->v_mount;
 2104         ltype = VOP_ISLOCKED(vp);
 2105         KASSERT(ltype == LK_EXCLUSIVE || ltype == LK_SHARED,
 2106             ("vn_vget_ino: vp not locked"));
 2107         error = vfs_busy(mp, MBF_NOWAIT);
 2108         if (error != 0) {
 2109                 vfs_ref(mp);
 2110                 VOP_UNLOCK(vp, 0);
 2111                 error = vfs_busy(mp, 0);
 2112                 vn_lock(vp, ltype | LK_RETRY);
 2113                 vfs_rel(mp);
 2114                 if (error != 0)
 2115                         return (ENOENT);
 2116                 if (vp->v_iflag & VI_DOOMED) {
 2117                         vfs_unbusy(mp);
 2118                         return (ENOENT);
 2119                 }
 2120         }
 2121         VOP_UNLOCK(vp, 0);
 2122         error = alloc(mp, alloc_arg, lkflags, rvp);
 2123         vfs_unbusy(mp);
 2124         if (*rvp != vp)
 2125                 vn_lock(vp, ltype | LK_RETRY);
 2126         if (vp->v_iflag & VI_DOOMED) {
 2127                 if (error == 0) {
 2128                         if (*rvp == vp)
 2129                                 vunref(vp);
 2130                         else
 2131                                 vput(*rvp);
 2132                 }
 2133                 error = ENOENT;
 2134         }
 2135         return (error);
 2136 }
 2137 
 2138 int
 2139 vn_rlimit_fsize(const struct vnode *vp, const struct uio *uio,
 2140     const struct thread *td)
 2141 {
 2142 
 2143         if (vp->v_type != VREG || td == NULL)
 2144                 return (0);
 2145         PROC_LOCK(td->td_proc);
 2146         if ((uoff_t)uio->uio_offset + uio->uio_resid >
 2147             lim_cur(td->td_proc, RLIMIT_FSIZE)) {
 2148                 kern_psignal(td->td_proc, SIGXFSZ);
 2149                 PROC_UNLOCK(td->td_proc);
 2150                 return (EFBIG);
 2151         }
 2152         PROC_UNLOCK(td->td_proc);
 2153         return (0);
 2154 }
 2155 
 2156 int
 2157 vn_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
 2158     struct thread *td)
 2159 {
 2160         struct vnode *vp;
 2161 
 2162         vp = fp->f_vnode;
 2163 #ifdef AUDIT
 2164         vn_lock(vp, LK_SHARED | LK_RETRY);
 2165         AUDIT_ARG_VNODE1(vp);
 2166         VOP_UNLOCK(vp, 0);
 2167 #endif
 2168         return (setfmode(td, active_cred, vp, mode));
 2169 }
 2170 
 2171 int
 2172 vn_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
 2173     struct thread *td)
 2174 {
 2175         struct vnode *vp;
 2176 
 2177         vp = fp->f_vnode;
 2178 #ifdef AUDIT
 2179         vn_lock(vp, LK_SHARED | LK_RETRY);
 2180         AUDIT_ARG_VNODE1(vp);
 2181         VOP_UNLOCK(vp, 0);
 2182 #endif
 2183         return (setfown(td, active_cred, vp, uid, gid));
 2184 }
 2185 
 2186 void
 2187 vn_pages_remove(struct vnode *vp, vm_pindex_t start, vm_pindex_t end)
 2188 {
 2189         vm_object_t object;
 2190 
 2191         if ((object = vp->v_object) == NULL)
 2192                 return;
 2193         VM_OBJECT_WLOCK(object);
 2194         vm_object_page_remove(object, start, end, 0);
 2195         VM_OBJECT_WUNLOCK(object);
 2196 }
 2197 
 2198 int
 2199 vn_bmap_seekhole(struct vnode *vp, u_long cmd, off_t *off, struct ucred *cred)
 2200 {
 2201         struct vattr va;
 2202         daddr_t bn, bnp;
 2203         uint64_t bsize;
 2204         off_t noff;
 2205         int error;
 2206 
 2207         KASSERT(cmd == FIOSEEKHOLE || cmd == FIOSEEKDATA,
 2208             ("Wrong command %lu", cmd));
 2209 
 2210         if (vn_lock(vp, LK_SHARED) != 0)
 2211                 return (EBADF);
 2212         if (vp->v_type != VREG) {
 2213                 error = ENOTTY;
 2214                 goto unlock;
 2215         }
 2216         error = VOP_GETATTR(vp, &va, cred);
 2217         if (error != 0)
 2218                 goto unlock;
 2219         noff = *off;
 2220         if (noff >= va.va_size) {
 2221                 error = ENXIO;
 2222                 goto unlock;
 2223         }
 2224         bsize = vp->v_mount->mnt_stat.f_iosize;
 2225         for (bn = noff / bsize; noff < va.va_size; bn++, noff += bsize) {
 2226                 error = VOP_BMAP(vp, bn, NULL, &bnp, NULL, NULL);
 2227                 if (error == EOPNOTSUPP) {
 2228                         error = ENOTTY;
 2229                         goto unlock;
 2230                 }
 2231                 if ((bnp == -1 && cmd == FIOSEEKHOLE) ||
 2232                     (bnp != -1 && cmd == FIOSEEKDATA)) {
 2233                         noff = bn * bsize;
 2234                         if (noff < *off)
 2235                                 noff = *off;
 2236                         goto unlock;
 2237                 }
 2238         }
 2239         if (noff > va.va_size)
 2240                 noff = va.va_size;
 2241         /* noff == va.va_size. There is an implicit hole at the end of file. */
 2242         if (cmd == FIOSEEKDATA)
 2243                 error = ENXIO;
 2244 unlock:
 2245         VOP_UNLOCK(vp, 0);
 2246         if (error == 0)
 2247                 *off = noff;
 2248         return (error);
 2249 }
 2250 
 2251 int
 2252 vn_seek(struct file *fp, off_t offset, int whence, struct thread *td)
 2253 {
 2254         struct ucred *cred;
 2255         struct vnode *vp;
 2256         struct vattr vattr;
 2257         off_t foffset, size;
 2258         int error, noneg;
 2259 
 2260         cred = td->td_ucred;
 2261         vp = fp->f_vnode;
 2262         foffset = foffset_lock(fp, 0);
 2263         noneg = (vp->v_type != VCHR);
 2264         error = 0;
 2265         switch (whence) {
 2266         case L_INCR:
 2267                 if (noneg &&
 2268                     (foffset < 0 ||
 2269                     (offset > 0 && foffset > OFF_MAX - offset))) {
 2270                         error = EOVERFLOW;
 2271                         break;
 2272                 }
 2273                 offset += foffset;
 2274                 break;
 2275         case L_XTND:
 2276                 vn_lock(vp, LK_SHARED | LK_RETRY);
 2277                 error = VOP_GETATTR(vp, &vattr, cred);
 2278                 VOP_UNLOCK(vp, 0);
 2279                 if (error)
 2280                         break;
 2281 
 2282                 /*
 2283                  * If the file references a disk device, then fetch
 2284                  * the media size and use that to determine the ending
 2285                  * offset.
 2286                  */
 2287                 if (vattr.va_size == 0 && vp->v_type == VCHR &&
 2288                     fo_ioctl(fp, DIOCGMEDIASIZE, &size, cred, td) == 0)
 2289                         vattr.va_size = size;
 2290                 if (noneg &&
 2291                     (vattr.va_size > OFF_MAX ||
 2292                     (offset > 0 && vattr.va_size > OFF_MAX - offset))) {
 2293                         error = EOVERFLOW;
 2294                         break;
 2295                 }
 2296                 offset += vattr.va_size;
 2297                 break;
 2298         case L_SET:
 2299                 break;
 2300         case SEEK_DATA:
 2301                 error = fo_ioctl(fp, FIOSEEKDATA, &offset, cred, td);
 2302                 break;
 2303         case SEEK_HOLE:
 2304                 error = fo_ioctl(fp, FIOSEEKHOLE, &offset, cred, td);
 2305                 break;
 2306         default:
 2307                 error = EINVAL;
 2308         }
 2309         if (error == 0 && noneg && offset < 0)
 2310                 error = EINVAL;
 2311         if (error != 0)
 2312                 goto drop;
 2313         VFS_KNOTE_UNLOCKED(vp, 0);
 2314         *(off_t *)(td->td_retval) = offset;
 2315 drop:
 2316         foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
 2317         return (error);
 2318 }
 2319 
 2320 int
 2321 vn_utimes_perm(struct vnode *vp, struct vattr *vap, struct ucred *cred,
 2322     struct thread *td)
 2323 {
 2324         int error;
 2325 
 2326         /*
 2327          * Grant permission if the caller is the owner of the file, or
 2328          * the super-user, or has ACL_WRITE_ATTRIBUTES permission on
 2329          * on the file.  If the time pointer is null, then write
 2330          * permission on the file is also sufficient.
 2331          *
 2332          * From NFSv4.1, draft 21, 6.2.1.3.1, Discussion of Mask Attributes:
 2333          * A user having ACL_WRITE_DATA or ACL_WRITE_ATTRIBUTES
 2334          * will be allowed to set the times [..] to the current
 2335          * server time.
 2336          */
 2337         error = VOP_ACCESSX(vp, VWRITE_ATTRIBUTES, cred, td);
 2338         if (error != 0 && (vap->va_vaflags & VA_UTIMES_NULL) != 0)
 2339                 error = VOP_ACCESS(vp, VWRITE, cred, td);
 2340         return (error);
 2341 }

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