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  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)vfs_vnops.c 8.2 (Berkeley) 1/21/94
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD$");
   39 
   40 #include "opt_mac.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/fcntl.h>
   45 #include <sys/file.h>
   46 #include <sys/kdb.h>
   47 #include <sys/stat.h>
   48 #include <sys/priv.h>
   49 #include <sys/proc.h>
   50 #include <sys/limits.h>
   51 #include <sys/lock.h>
   52 #include <sys/mount.h>
   53 #include <sys/mutex.h>
   54 #include <sys/namei.h>
   55 #include <sys/vnode.h>
   56 #include <sys/bio.h>
   57 #include <sys/buf.h>
   58 #include <sys/filio.h>
   59 #include <sys/sx.h>
   60 #include <sys/ttycom.h>
   61 #include <sys/conf.h>
   62 #include <sys/syslog.h>
   63 #include <sys/unistd.h>
   64 
   65 #include <security/mac/mac_framework.h>
   66 
   67 static fo_rdwr_t        vn_read;
   68 static fo_rdwr_t        vn_write;
   69 static fo_ioctl_t       vn_ioctl;
   70 static fo_poll_t        vn_poll;
   71 static fo_kqfilter_t    vn_kqfilter;
   72 static fo_stat_t        vn_statfile;
   73 static fo_close_t       vn_closefile;
   74 
   75 struct  fileops vnops = {
   76         .fo_read = vn_read,
   77         .fo_write = vn_write,
   78         .fo_ioctl = vn_ioctl,
   79         .fo_poll = vn_poll,
   80         .fo_kqfilter = vn_kqfilter,
   81         .fo_stat = vn_statfile,
   82         .fo_close = vn_closefile,
   83         .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE
   84 };
   85 
   86 int
   87 vn_open(ndp, flagp, cmode, fp)
   88         struct nameidata *ndp;
   89         int *flagp, cmode;
   90         struct file *fp;
   91 {
   92         struct thread *td = ndp->ni_cnd.cn_thread;
   93 
   94         return (vn_open_cred(ndp, flagp, cmode, td->td_ucred, fp));
   95 }
   96 
   97 /*
   98  * Common code for vnode open operations.
   99  * Check permissions, and call the VOP_OPEN or VOP_CREATE routine.
  100  * 
  101  * Note that this does NOT free nameidata for the successful case,
  102  * due to the NDINIT being done elsewhere.
  103  */
  104 int
  105 vn_open_cred(ndp, flagp, cmode, cred, fp)
  106         struct nameidata *ndp;
  107         int *flagp, cmode;
  108         struct ucred *cred;
  109         struct file *fp;
  110 {
  111         struct vnode *vp;
  112         struct mount *mp;
  113         struct thread *td = ndp->ni_cnd.cn_thread;
  114         struct vattr vat;
  115         struct vattr *vap = &vat;
  116         int mode, fmode, error;
  117         int vfslocked, mpsafe;
  118 
  119         mpsafe = ndp->ni_cnd.cn_flags & MPSAFE;
  120 restart:
  121         vfslocked = 0;
  122         fmode = *flagp;
  123         if (fmode & O_CREAT) {
  124                 ndp->ni_cnd.cn_nameiop = CREATE;
  125                 ndp->ni_cnd.cn_flags = ISOPEN | LOCKPARENT | LOCKLEAF |
  126                     MPSAFE | AUDITVNODE1;
  127                 if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
  128                         ndp->ni_cnd.cn_flags |= FOLLOW;
  129                 bwillwrite();
  130                 if ((error = namei(ndp)) != 0)
  131                         return (error);
  132                 vfslocked = NDHASGIANT(ndp);
  133                 if (!mpsafe)
  134                         ndp->ni_cnd.cn_flags &= ~MPSAFE;
  135                 if (ndp->ni_vp == NULL) {
  136                         VATTR_NULL(vap);
  137                         vap->va_type = VREG;
  138                         vap->va_mode = cmode;
  139                         if (fmode & O_EXCL)
  140                                 vap->va_vaflags |= VA_EXCLUSIVE;
  141                         if (vn_start_write(ndp->ni_dvp, &mp, V_NOWAIT) != 0) {
  142                                 NDFREE(ndp, NDF_ONLY_PNBUF);
  143                                 vput(ndp->ni_dvp);
  144                                 VFS_UNLOCK_GIANT(vfslocked);
  145                                 if ((error = vn_start_write(NULL, &mp,
  146                                     V_XSLEEP | PCATCH)) != 0)
  147                                         return (error);
  148                                 goto restart;
  149                         }
  150 #ifdef MAC
  151                         error = mac_check_vnode_create(cred, ndp->ni_dvp,
  152                             &ndp->ni_cnd, vap);
  153                         if (error == 0) {
  154 #endif
  155                                 VOP_LEASE(ndp->ni_dvp, td, cred, LEASE_WRITE);
  156                                 error = VOP_CREATE(ndp->ni_dvp, &ndp->ni_vp,
  157                                                    &ndp->ni_cnd, vap);
  158 #ifdef MAC
  159                         }
  160 #endif
  161                         vput(ndp->ni_dvp);
  162                         vn_finished_write(mp);
  163                         if (error) {
  164                                 VFS_UNLOCK_GIANT(vfslocked);
  165                                 NDFREE(ndp, NDF_ONLY_PNBUF);
  166                                 return (error);
  167                         }
  168                         fmode &= ~O_TRUNC;
  169                         vp = ndp->ni_vp;
  170                 } else {
  171                         if (ndp->ni_dvp == ndp->ni_vp)
  172                                 vrele(ndp->ni_dvp);
  173                         else
  174                                 vput(ndp->ni_dvp);
  175                         ndp->ni_dvp = NULL;
  176                         vp = ndp->ni_vp;
  177                         if (fmode & O_EXCL) {
  178                                 error = EEXIST;
  179                                 goto bad;
  180                         }
  181                         fmode &= ~O_CREAT;
  182                 }
  183         } else {
  184                 ndp->ni_cnd.cn_nameiop = LOOKUP;
  185                 ndp->ni_cnd.cn_flags = ISOPEN |
  186                     ((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) |
  187                     LOCKLEAF | MPSAFE | AUDITVNODE1;
  188                 if ((error = namei(ndp)) != 0)
  189                         return (error);
  190                 if (!mpsafe)
  191                         ndp->ni_cnd.cn_flags &= ~MPSAFE;
  192                 vfslocked = NDHASGIANT(ndp);
  193                 vp = ndp->ni_vp;
  194         }
  195         if (vp->v_type == VLNK) {
  196                 error = EMLINK;
  197                 goto bad;
  198         }
  199         if (vp->v_type == VSOCK) {
  200                 error = EOPNOTSUPP;
  201                 goto bad;
  202         }
  203         mode = 0;
  204         if (fmode & (FWRITE | O_TRUNC)) {
  205                 if (vp->v_type == VDIR) {
  206                         error = EISDIR;
  207                         goto bad;
  208                 }
  209                 mode |= VWRITE;
  210         }
  211         if (fmode & FREAD)
  212                 mode |= VREAD;
  213         if (fmode & O_APPEND)
  214                 mode |= VAPPEND;
  215 #ifdef MAC
  216         error = mac_check_vnode_open(cred, vp, mode);
  217         if (error)
  218                 goto bad;
  219 #endif
  220         if ((fmode & O_CREAT) == 0) {
  221                 if (mode & VWRITE) {
  222                         error = vn_writechk(vp);
  223                         if (error)
  224                                 goto bad;
  225                 }
  226                 if (mode) {
  227                         error = VOP_ACCESS(vp, mode, cred, td);
  228                         if (error)
  229                                 goto bad;
  230                 }
  231         }
  232         if ((error = VOP_OPEN(vp, fmode, cred, td, fp)) != 0)
  233                 goto bad;
  234 
  235         if (fmode & FWRITE)
  236                 vp->v_writecount++;
  237         *flagp = fmode;
  238         ASSERT_VOP_ELOCKED(vp, "vn_open_cred");
  239         if (!mpsafe)
  240                 VFS_UNLOCK_GIANT(vfslocked);
  241         return (0);
  242 bad:
  243         NDFREE(ndp, NDF_ONLY_PNBUF);
  244         vput(vp);
  245         VFS_UNLOCK_GIANT(vfslocked);
  246         *flagp = fmode;
  247         ndp->ni_vp = NULL;
  248         return (error);
  249 }
  250 
  251 /*
  252  * Check for write permissions on the specified vnode.
  253  * Prototype text segments cannot be written.
  254  */
  255 int
  256 vn_writechk(vp)
  257         register struct vnode *vp;
  258 {
  259 
  260         ASSERT_VOP_LOCKED(vp, "vn_writechk");
  261         /*
  262          * If there's shared text associated with
  263          * the vnode, try to free it up once.  If
  264          * we fail, we can't allow writing.
  265          */
  266         if (vp->v_vflag & VV_TEXT)
  267                 return (ETXTBSY);
  268 
  269         return (0);
  270 }
  271 
  272 /*
  273  * Vnode close call
  274  */
  275 int
  276 vn_close(vp, flags, file_cred, td)
  277         register struct vnode *vp;
  278         int flags;
  279         struct ucred *file_cred;
  280         struct thread *td;
  281 {
  282         struct mount *mp;
  283         int error;
  284 
  285         VFS_ASSERT_GIANT(vp->v_mount);
  286 
  287         vn_start_write(vp, &mp, V_WAIT);
  288         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
  289         if (flags & FWRITE) {
  290                 VNASSERT(vp->v_writecount > 0, vp, 
  291                     ("vn_close: negative writecount"));
  292                 vp->v_writecount--;
  293         }
  294         error = VOP_CLOSE(vp, flags, file_cred, td);
  295         vput(vp);
  296         vn_finished_write(mp);
  297         return (error);
  298 }
  299 
  300 /*
  301  * Sequential heuristic - detect sequential operation
  302  */
  303 static __inline
  304 int
  305 sequential_heuristic(struct uio *uio, struct file *fp)
  306 {
  307 
  308         if ((uio->uio_offset == 0 && fp->f_seqcount > 0) ||
  309             uio->uio_offset == fp->f_nextoff) {
  310                 /*
  311                  * XXX we assume that the filesystem block size is
  312                  * the default.  Not true, but still gives us a pretty
  313                  * good indicator of how sequential the read operations
  314                  * are.
  315                  */
  316                 fp->f_seqcount += (uio->uio_resid + BKVASIZE - 1) / BKVASIZE;
  317                 if (fp->f_seqcount > IO_SEQMAX)
  318                         fp->f_seqcount = IO_SEQMAX;
  319                 return(fp->f_seqcount << IO_SEQSHIFT);
  320         }
  321 
  322         /*
  323          * Not sequential, quick draw-down of seqcount
  324          */
  325         if (fp->f_seqcount > 1)
  326                 fp->f_seqcount = 1;
  327         else
  328                 fp->f_seqcount = 0;
  329         return(0);
  330 }
  331 
  332 /*
  333  * Package up an I/O request on a vnode into a uio and do it.
  334  */
  335 int
  336 vn_rdwr(rw, vp, base, len, offset, segflg, ioflg, active_cred, file_cred,
  337     aresid, td)
  338         enum uio_rw rw;
  339         struct vnode *vp;
  340         void *base;
  341         int len;
  342         off_t offset;
  343         enum uio_seg segflg;
  344         int ioflg;
  345         struct ucred *active_cred;
  346         struct ucred *file_cred;
  347         int *aresid;
  348         struct thread *td;
  349 {
  350         struct uio auio;
  351         struct iovec aiov;
  352         struct mount *mp;
  353         struct ucred *cred;
  354         int error;
  355 
  356         VFS_ASSERT_GIANT(vp->v_mount);
  357 
  358         if ((ioflg & IO_NODELOCKED) == 0) {
  359                 mp = NULL;
  360                 if (rw == UIO_WRITE) { 
  361                         if (vp->v_type != VCHR &&
  362                             (error = vn_start_write(vp, &mp, V_WAIT | PCATCH))
  363                             != 0)
  364                                 return (error);
  365                         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
  366                 } else {
  367                         /*
  368                          * XXX This should be LK_SHARED but I don't trust VFS
  369                          * enough to leave it like that until it has been
  370                          * reviewed further.
  371                          */
  372                         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
  373                 }
  374 
  375         }
  376         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
  377         auio.uio_iov = &aiov;
  378         auio.uio_iovcnt = 1;
  379         aiov.iov_base = base;
  380         aiov.iov_len = len;
  381         auio.uio_resid = len;
  382         auio.uio_offset = offset;
  383         auio.uio_segflg = segflg;
  384         auio.uio_rw = rw;
  385         auio.uio_td = td;
  386         error = 0;
  387 #ifdef MAC
  388         if ((ioflg & IO_NOMACCHECK) == 0) {
  389                 if (rw == UIO_READ)
  390                         error = mac_check_vnode_read(active_cred, file_cred,
  391                             vp);
  392                 else
  393                         error = mac_check_vnode_write(active_cred, file_cred,
  394                             vp);
  395         }
  396 #endif
  397         if (error == 0) {
  398                 if (file_cred)
  399                         cred = file_cred;
  400                 else
  401                         cred = active_cred;
  402                 if (rw == UIO_READ)
  403                         error = VOP_READ(vp, &auio, ioflg, cred);
  404                 else
  405                         error = VOP_WRITE(vp, &auio, ioflg, cred);
  406         }
  407         if (aresid)
  408                 *aresid = auio.uio_resid;
  409         else
  410                 if (auio.uio_resid && error == 0)
  411                         error = EIO;
  412         if ((ioflg & IO_NODELOCKED) == 0) {
  413                 if (rw == UIO_WRITE && vp->v_type != VCHR)
  414                         vn_finished_write(mp);
  415                 VOP_UNLOCK(vp, 0, td);
  416         }
  417         return (error);
  418 }
  419 
  420 /*
  421  * Package up an I/O request on a vnode into a uio and do it.  The I/O
  422  * request is split up into smaller chunks and we try to avoid saturating
  423  * the buffer cache while potentially holding a vnode locked, so we 
  424  * check bwillwrite() before calling vn_rdwr().  We also call uio_yield()
  425  * to give other processes a chance to lock the vnode (either other processes
  426  * core'ing the same binary, or unrelated processes scanning the directory).
  427  */
  428 int
  429 vn_rdwr_inchunks(rw, vp, base, len, offset, segflg, ioflg, active_cred,
  430     file_cred, aresid, td)
  431         enum uio_rw rw;
  432         struct vnode *vp;
  433         void *base;
  434         size_t len;
  435         off_t offset;
  436         enum uio_seg segflg;
  437         int ioflg;
  438         struct ucred *active_cred;
  439         struct ucred *file_cred;
  440         size_t *aresid;
  441         struct thread *td;
  442 {
  443         int error = 0;
  444         int iaresid;
  445 
  446         VFS_ASSERT_GIANT(vp->v_mount);
  447 
  448         do {
  449                 int chunk;
  450 
  451                 /*
  452                  * Force `offset' to a multiple of MAXBSIZE except possibly
  453                  * for the first chunk, so that filesystems only need to
  454                  * write full blocks except possibly for the first and last
  455                  * chunks.
  456                  */
  457                 chunk = MAXBSIZE - (uoff_t)offset % MAXBSIZE;
  458 
  459                 if (chunk > len)
  460                         chunk = len;
  461                 if (rw != UIO_READ && vp->v_type == VREG)
  462                         bwillwrite();
  463                 iaresid = 0;
  464                 error = vn_rdwr(rw, vp, base, chunk, offset, segflg,
  465                     ioflg, active_cred, file_cred, &iaresid, td);
  466                 len -= chunk;   /* aresid calc already includes length */
  467                 if (error)
  468                         break;
  469                 offset += chunk;
  470                 base = (char *)base + chunk;
  471                 uio_yield();
  472         } while (len);
  473         if (aresid)
  474                 *aresid = len + iaresid;
  475         return (error);
  476 }
  477 
  478 /*
  479  * File table vnode read routine.
  480  */
  481 static int
  482 vn_read(fp, uio, active_cred, flags, td)
  483         struct file *fp;
  484         struct uio *uio;
  485         struct ucred *active_cred;
  486         struct thread *td;
  487         int flags;
  488 {
  489         struct vnode *vp;
  490         int error, ioflag;
  491         int vfslocked;
  492 
  493         KASSERT(uio->uio_td == td, ("uio_td %p is not td %p",
  494             uio->uio_td, td));
  495         vp = fp->f_vnode;
  496         ioflag = 0;
  497         if (fp->f_flag & FNONBLOCK)
  498                 ioflag |= IO_NDELAY;
  499         if (fp->f_flag & O_DIRECT)
  500                 ioflag |= IO_DIRECT;
  501         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  502         VOP_LEASE(vp, td, fp->f_cred, LEASE_READ);
  503         /*
  504          * According to McKusick the vn lock was protecting f_offset here.
  505          * It is now protected by the FOFFSET_LOCKED flag.
  506          */
  507         if ((flags & FOF_OFFSET) == 0) {
  508                 FILE_LOCK(fp);
  509                 while(fp->f_vnread_flags & FOFFSET_LOCKED) {
  510                         fp->f_vnread_flags |= FOFFSET_LOCK_WAITING;
  511                         msleep(&fp->f_vnread_flags,fp->f_mtxp,PUSER -1,"vnread offlock",0);
  512                 }
  513                 fp->f_vnread_flags |= FOFFSET_LOCKED;
  514                 FILE_UNLOCK(fp);
  515                 vn_lock(vp, LK_SHARED | LK_RETRY, td);
  516                 uio->uio_offset = fp->f_offset;
  517         } else
  518                 vn_lock(vp, LK_SHARED | LK_RETRY, td);
  519 
  520         ioflag |= sequential_heuristic(uio, fp);
  521 
  522 #ifdef MAC
  523         error = mac_check_vnode_read(active_cred, fp->f_cred, vp);
  524         if (error == 0)
  525 #endif
  526                 error = VOP_READ(vp, uio, ioflag, fp->f_cred);
  527         if ((flags & FOF_OFFSET) == 0) {
  528                 fp->f_offset = uio->uio_offset;
  529                 FILE_LOCK(fp);
  530                 if (fp->f_vnread_flags & FOFFSET_LOCK_WAITING)
  531                         wakeup(&fp->f_vnread_flags);
  532                 fp->f_vnread_flags = 0;
  533                 FILE_UNLOCK(fp);
  534         }
  535         fp->f_nextoff = uio->uio_offset;
  536         VOP_UNLOCK(vp, 0, td);
  537         VFS_UNLOCK_GIANT(vfslocked);
  538         return (error);
  539 }
  540 
  541 /*
  542  * File table vnode write routine.
  543  */
  544 static int
  545 vn_write(fp, uio, active_cred, flags, td)
  546         struct file *fp;
  547         struct uio *uio;
  548         struct ucred *active_cred;
  549         struct thread *td;
  550         int flags;
  551 {
  552         struct vnode *vp;
  553         struct mount *mp;
  554         int error, ioflag;
  555         int vfslocked;
  556 
  557         KASSERT(uio->uio_td == td, ("uio_td %p is not td %p",
  558             uio->uio_td, td));
  559         vp = fp->f_vnode;
  560         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  561         if (vp->v_type == VREG)
  562                 bwillwrite();
  563         ioflag = IO_UNIT;
  564         if (vp->v_type == VREG && (fp->f_flag & O_APPEND))
  565                 ioflag |= IO_APPEND;
  566         if (fp->f_flag & FNONBLOCK)
  567                 ioflag |= IO_NDELAY;
  568         if (fp->f_flag & O_DIRECT)
  569                 ioflag |= IO_DIRECT;
  570         if ((fp->f_flag & O_FSYNC) ||
  571             (vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS)))
  572                 ioflag |= IO_SYNC;
  573         mp = NULL;
  574         if (vp->v_type != VCHR &&
  575             (error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) != 0)
  576                 goto unlock;
  577         VOP_LEASE(vp, td, fp->f_cred, LEASE_WRITE);
  578         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
  579         if ((flags & FOF_OFFSET) == 0)
  580                 uio->uio_offset = fp->f_offset;
  581         ioflag |= sequential_heuristic(uio, fp);
  582 #ifdef MAC
  583         error = mac_check_vnode_write(active_cred, fp->f_cred, vp);
  584         if (error == 0)
  585 #endif
  586                 error = VOP_WRITE(vp, uio, ioflag, fp->f_cred);
  587         if ((flags & FOF_OFFSET) == 0)
  588                 fp->f_offset = uio->uio_offset;
  589         fp->f_nextoff = uio->uio_offset;
  590         VOP_UNLOCK(vp, 0, td);
  591         if (vp->v_type != VCHR)
  592                 vn_finished_write(mp);
  593 unlock:
  594         VFS_UNLOCK_GIANT(vfslocked);
  595         return (error);
  596 }
  597 
  598 /*
  599  * File table vnode stat routine.
  600  */
  601 static int
  602 vn_statfile(fp, sb, active_cred, td)
  603         struct file *fp;
  604         struct stat *sb;
  605         struct ucred *active_cred;
  606         struct thread *td;
  607 {
  608         struct vnode *vp = fp->f_vnode;
  609         int vfslocked;
  610         int error;
  611 
  612         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  613         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
  614         error = vn_stat(vp, sb, active_cred, fp->f_cred, td);
  615         VOP_UNLOCK(vp, 0, td);
  616         VFS_UNLOCK_GIANT(vfslocked);
  617 
  618         return (error);
  619 }
  620 
  621 /*
  622  * Stat a vnode; implementation for the stat syscall
  623  */
  624 int
  625 vn_stat(vp, sb, active_cred, file_cred, td)
  626         struct vnode *vp;
  627         register struct stat *sb;
  628         struct ucred *active_cred;
  629         struct ucred *file_cred;
  630         struct thread *td;
  631 {
  632         struct vattr vattr;
  633         register struct vattr *vap;
  634         int error;
  635         u_short mode;
  636 
  637 #ifdef MAC
  638         error = mac_check_vnode_stat(active_cred, file_cred, vp);
  639         if (error)
  640                 return (error);
  641 #endif
  642 
  643         vap = &vattr;
  644         error = VOP_GETATTR(vp, vap, active_cred, td);
  645         if (error)
  646                 return (error);
  647 
  648         /*
  649          * Zero the spare stat fields
  650          */
  651         bzero(sb, sizeof *sb);
  652 
  653         /*
  654          * Copy from vattr table
  655          */
  656         if (vap->va_fsid != VNOVAL)
  657                 sb->st_dev = vap->va_fsid;
  658         else
  659                 sb->st_dev = vp->v_mount->mnt_stat.f_fsid.val[0];
  660         sb->st_ino = vap->va_fileid;
  661         mode = vap->va_mode;
  662         switch (vap->va_type) {
  663         case VREG:
  664                 mode |= S_IFREG;
  665                 break;
  666         case VDIR:
  667                 mode |= S_IFDIR;
  668                 break;
  669         case VBLK:
  670                 mode |= S_IFBLK;
  671                 break;
  672         case VCHR:
  673                 mode |= S_IFCHR;
  674                 break;
  675         case VLNK:
  676                 mode |= S_IFLNK;
  677                 break;
  678         case VSOCK:
  679                 mode |= S_IFSOCK;
  680                 break;
  681         case VFIFO:
  682                 mode |= S_IFIFO;
  683                 break;
  684         default:
  685                 return (EBADF);
  686         };
  687         sb->st_mode = mode;
  688         sb->st_nlink = vap->va_nlink;
  689         sb->st_uid = vap->va_uid;
  690         sb->st_gid = vap->va_gid;
  691         sb->st_rdev = vap->va_rdev;
  692         if (vap->va_size > OFF_MAX)
  693                 return (EOVERFLOW);
  694         sb->st_size = vap->va_size;
  695         sb->st_atimespec = vap->va_atime;
  696         sb->st_mtimespec = vap->va_mtime;
  697         sb->st_ctimespec = vap->va_ctime;
  698         sb->st_birthtimespec = vap->va_birthtime;
  699 
  700         /*
  701          * According to www.opengroup.org, the meaning of st_blksize is 
  702          *   "a filesystem-specific preferred I/O block size for this 
  703          *    object.  In some filesystem types, this may vary from file
  704          *    to file"
  705          * Default to PAGE_SIZE after much discussion.
  706          * XXX: min(PAGE_SIZE, vp->v_bufobj.bo_bsize) may be more correct.
  707          */
  708 
  709         sb->st_blksize = PAGE_SIZE;
  710         
  711         sb->st_flags = vap->va_flags;
  712         if (priv_check(td, PRIV_VFS_GENERATION))
  713                 sb->st_gen = 0;
  714         else
  715                 sb->st_gen = vap->va_gen;
  716 
  717         sb->st_blocks = vap->va_bytes / S_BLKSIZE;
  718         return (0);
  719 }
  720 
  721 /*
  722  * File table vnode ioctl routine.
  723  */
  724 static int
  725 vn_ioctl(fp, com, data, active_cred, td)
  726         struct file *fp;
  727         u_long com;
  728         void *data;
  729         struct ucred *active_cred;
  730         struct thread *td;
  731 {
  732         struct vnode *vp = fp->f_vnode;
  733         struct vattr vattr;
  734         int vfslocked;
  735         int error;
  736 
  737         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  738         error = ENOTTY;
  739         switch (vp->v_type) {
  740         case VREG:
  741         case VDIR:
  742                 if (com == FIONREAD) {
  743                         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
  744                         error = VOP_GETATTR(vp, &vattr, active_cred, td);
  745                         VOP_UNLOCK(vp, 0, td);
  746                         if (!error)
  747                                 *(int *)data = vattr.va_size - fp->f_offset;
  748                 }
  749                 if (com == FIONBIO || com == FIOASYNC)  /* XXX */
  750                         error = 0;
  751                 else
  752                         error = VOP_IOCTL(vp, com, data, fp->f_flag,
  753                             active_cred, td);
  754                 break;
  755 
  756         default:
  757                 break;
  758         }
  759         VFS_UNLOCK_GIANT(vfslocked);
  760         return (error);
  761 }
  762 
  763 /*
  764  * File table vnode poll routine.
  765  */
  766 static int
  767 vn_poll(fp, events, active_cred, td)
  768         struct file *fp;
  769         int events;
  770         struct ucred *active_cred;
  771         struct thread *td;
  772 {
  773         struct vnode *vp;
  774         int vfslocked;
  775         int error;
  776 
  777         vp = fp->f_vnode;
  778         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  779 #ifdef MAC
  780         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
  781         error = mac_check_vnode_poll(active_cred, fp->f_cred, vp);
  782         VOP_UNLOCK(vp, 0, td);
  783         if (!error)
  784 #endif
  785 
  786         error = VOP_POLL(vp, events, fp->f_cred, td);
  787         VFS_UNLOCK_GIANT(vfslocked);
  788         return (error);
  789 }
  790 
  791 /*
  792  * Check that the vnode is still valid, and if so
  793  * acquire requested lock.
  794  */
  795 int
  796 _vn_lock(struct vnode *vp, int flags, struct thread *td, char *file, int line)
  797 {
  798         int error;
  799 
  800         do {
  801                 if ((flags & LK_INTERLOCK) == 0)
  802                         VI_LOCK(vp);
  803 #ifdef DEBUG_VFS_LOCKS
  804                 KASSERT(vp->v_holdcnt != 0,
  805                     ("vn_lock %p: zero hold count", vp));
  806 #endif
  807                 if ((flags & LK_NOWAIT || (flags & LK_TYPE_MASK) == 0) &&
  808                     vp->v_iflag & VI_DOOMED) {
  809                         VI_UNLOCK(vp);
  810                         return (ENOENT);
  811                 }
  812                 /*
  813                  * Just polling to check validity.
  814                  */
  815                 if ((flags & LK_TYPE_MASK) == 0) {
  816                         VI_UNLOCK(vp);
  817                         return (0);
  818                 }
  819                 /*
  820                  * lockmgr drops interlock before it will return for
  821                  * any reason.  So force the code above to relock it.
  822                  */
  823                 error = VOP_LOCK1(vp, flags | LK_INTERLOCK, td, file, line);
  824                 flags &= ~LK_INTERLOCK;
  825                 KASSERT((flags & LK_RETRY) == 0 || error == 0,
  826                     ("LK_RETRY set with incompatible flags %d\n", flags));
  827                 /*
  828                  * Callers specify LK_RETRY if they wish to get dead vnodes.
  829                  * If RETRY is not set, we return ENOENT instead.
  830                  */
  831                 if (error == 0 && vp->v_iflag & VI_DOOMED &&
  832                     (flags & LK_RETRY) == 0) {
  833                         VOP_UNLOCK(vp, 0, td);
  834                         error = ENOENT;
  835                         break;
  836                 }
  837         } while (flags & LK_RETRY && error != 0);
  838         return (error);
  839 }
  840 
  841 /*
  842  * File table vnode close routine.
  843  */
  844 static int
  845 vn_closefile(fp, td)
  846         struct file *fp;
  847         struct thread *td;
  848 {
  849         struct vnode *vp;
  850         struct flock lf;
  851         int vfslocked;
  852         int error;
  853 
  854         vp = fp->f_vnode;
  855 
  856         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  857         if (fp->f_type == DTYPE_VNODE && fp->f_flag & FHASLOCK) {
  858                 lf.l_whence = SEEK_SET;
  859                 lf.l_start = 0;
  860                 lf.l_len = 0;
  861                 lf.l_type = F_UNLCK;
  862                 (void) VOP_ADVLOCK(vp, fp, F_UNLCK, &lf, F_FLOCK);
  863         }
  864 
  865         fp->f_ops = &badfileops;
  866 
  867         error = vn_close(vp, fp->f_flag, fp->f_cred, td);
  868         VFS_UNLOCK_GIANT(vfslocked);
  869         return (error);
  870 }
  871 
  872 /*
  873  * Preparing to start a filesystem write operation. If the operation is
  874  * permitted, then we bump the count of operations in progress and
  875  * proceed. If a suspend request is in progress, we wait until the
  876  * suspension is over, and then proceed.
  877  */
  878 int
  879 vn_start_write(vp, mpp, flags)
  880         struct vnode *vp;
  881         struct mount **mpp;
  882         int flags;
  883 {
  884         struct mount *mp;
  885         int error;
  886 
  887         error = 0;
  888         /*
  889          * If a vnode is provided, get and return the mount point that
  890          * to which it will write.
  891          */
  892         if (vp != NULL) {
  893                 if ((error = VOP_GETWRITEMOUNT(vp, mpp)) != 0) {
  894                         *mpp = NULL;
  895                         if (error != EOPNOTSUPP)
  896                                 return (error);
  897                         return (0);
  898                 }
  899         }
  900         if ((mp = *mpp) == NULL)
  901                 return (0);
  902         MNT_ILOCK(mp);
  903         if (vp == NULL)
  904                 MNT_REF(mp);
  905         /*
  906          * Check on status of suspension.
  907          */
  908         while ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0) {
  909                 if (flags & V_NOWAIT) {
  910                         error = EWOULDBLOCK;
  911                         goto unlock;
  912                 }
  913                 error = msleep(&mp->mnt_flag, MNT_MTX(mp), 
  914                     (PUSER - 1) | (flags & PCATCH), "suspfs", 0);
  915                 if (error)
  916                         goto unlock;
  917         }
  918         if (flags & V_XSLEEP)
  919                 goto unlock;
  920         mp->mnt_writeopcount++;
  921 unlock:
  922         MNT_REL(mp);
  923         MNT_IUNLOCK(mp);
  924         return (error);
  925 }
  926 
  927 /*
  928  * Secondary suspension. Used by operations such as vop_inactive
  929  * routines that are needed by the higher level functions. These
  930  * are allowed to proceed until all the higher level functions have
  931  * completed (indicated by mnt_writeopcount dropping to zero). At that
  932  * time, these operations are halted until the suspension is over.
  933  */
  934 int
  935 vn_write_suspend_wait(vp, mp, flags)
  936         struct vnode *vp;
  937         struct mount *mp;
  938         int flags;
  939 {
  940         int error;
  941 
  942         if (vp != NULL) {
  943                 if ((error = VOP_GETWRITEMOUNT(vp, &mp)) != 0) {
  944                         if (error != EOPNOTSUPP)
  945                                 return (error);
  946                         return (0);
  947                 }
  948         }
  949         /*
  950          * If we are not suspended or have not yet reached suspended
  951          * mode, then let the operation proceed.
  952          */
  953         if (mp == NULL)
  954                 return (0);
  955         MNT_ILOCK(mp);
  956         if (vp == NULL)
  957                 MNT_REF(mp);
  958         if ((mp->mnt_kern_flag & MNTK_SUSPENDED) == 0) {
  959                 MNT_REL(mp);
  960                 MNT_IUNLOCK(mp);
  961                 return (0);
  962         }
  963         if (flags & V_NOWAIT) {
  964                 MNT_REL(mp);
  965                 MNT_IUNLOCK(mp);
  966                 return (EWOULDBLOCK);
  967         }
  968         /*
  969          * Wait for the suspension to finish.
  970          */
  971         error = msleep(&mp->mnt_flag, MNT_MTX(mp),
  972             (PUSER - 1) | (flags & PCATCH) | PDROP, "suspfs", 0);
  973         vfs_rel(mp);
  974         return (error);
  975 }
  976 
  977 /*
  978  * Secondary suspension. Used by operations such as vop_inactive
  979  * routines that are needed by the higher level functions. These
  980  * are allowed to proceed until all the higher level functions have
  981  * completed (indicated by mnt_writeopcount dropping to zero). At that
  982  * time, these operations are halted until the suspension is over.
  983  */
  984 int
  985 vn_start_secondary_write(vp, mpp, flags)
  986         struct vnode *vp;
  987         struct mount **mpp;
  988         int flags;
  989 {
  990         struct mount *mp;
  991         int error;
  992 
  993  retry:
  994         if (vp != NULL) {
  995                 if ((error = VOP_GETWRITEMOUNT(vp, mpp)) != 0) {
  996                         *mpp = NULL;
  997                         if (error != EOPNOTSUPP)
  998                                 return (error);
  999                         return (0);
 1000                 }
 1001         }
 1002         /*
 1003          * If we are not suspended or have not yet reached suspended
 1004          * mode, then let the operation proceed.
 1005          */
 1006         if ((mp = *mpp) == NULL)
 1007                 return (0);
 1008         MNT_ILOCK(mp);
 1009         if (vp == NULL)
 1010                 MNT_REF(mp);
 1011         if ((mp->mnt_kern_flag & (MNTK_SUSPENDED | MNTK_SUSPEND2)) == 0) {
 1012                 mp->mnt_secondary_writes++;
 1013                 mp->mnt_secondary_accwrites++;
 1014                 MNT_REL(mp);
 1015                 MNT_IUNLOCK(mp);
 1016                 return (0);
 1017         }
 1018         if (flags & V_NOWAIT) {
 1019                 MNT_REL(mp);
 1020                 MNT_IUNLOCK(mp);
 1021                 return (EWOULDBLOCK);
 1022         }
 1023         /*
 1024          * Wait for the suspension to finish.
 1025          */
 1026         error = msleep(&mp->mnt_flag, MNT_MTX(mp),
 1027                        (PUSER - 1) | (flags & PCATCH) | PDROP, "suspfs", 0);
 1028         vfs_rel(mp);
 1029         if (error == 0)
 1030                 goto retry;
 1031         return (error);
 1032 }
 1033 
 1034 /*
 1035  * Filesystem write operation has completed. If we are suspending and this
 1036  * operation is the last one, notify the suspender that the suspension is
 1037  * now in effect.
 1038  */
 1039 void
 1040 vn_finished_write(mp)
 1041         struct mount *mp;
 1042 {
 1043         if (mp == NULL)
 1044                 return;
 1045         MNT_ILOCK(mp);
 1046         mp->mnt_writeopcount--;
 1047         if (mp->mnt_writeopcount < 0)
 1048                 panic("vn_finished_write: neg cnt");
 1049         if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0 &&
 1050             mp->mnt_writeopcount <= 0)
 1051                 wakeup(&mp->mnt_writeopcount);
 1052         MNT_IUNLOCK(mp);
 1053 }
 1054 
 1055 
 1056 /*
 1057  * Filesystem secondary write operation has completed. If we are
 1058  * suspending and this operation is the last one, notify the suspender
 1059  * that the suspension is now in effect.
 1060  */
 1061 void
 1062 vn_finished_secondary_write(mp)
 1063         struct mount *mp;
 1064 {
 1065         if (mp == NULL)
 1066                 return;
 1067         MNT_ILOCK(mp);
 1068         mp->mnt_secondary_writes--;
 1069         if (mp->mnt_secondary_writes < 0)
 1070                 panic("vn_finished_secondary_write: neg cnt");
 1071         if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0 &&
 1072             mp->mnt_secondary_writes <= 0)
 1073                 wakeup(&mp->mnt_secondary_writes);
 1074         MNT_IUNLOCK(mp);
 1075 }
 1076 
 1077 
 1078 
 1079 /*
 1080  * Request a filesystem to suspend write operations.
 1081  */
 1082 int
 1083 vfs_write_suspend(mp)
 1084         struct mount *mp;
 1085 {
 1086         struct thread *td = curthread;
 1087         int error;
 1088 
 1089         MNT_ILOCK(mp);
 1090         if (mp->mnt_kern_flag & MNTK_SUSPEND) {
 1091                 MNT_IUNLOCK(mp);
 1092                 return (0);
 1093         }
 1094         mp->mnt_kern_flag |= MNTK_SUSPEND;
 1095         if (mp->mnt_writeopcount > 0)
 1096                 (void) msleep(&mp->mnt_writeopcount, 
 1097                     MNT_MTX(mp), (PUSER - 1)|PDROP, "suspwt", 0);
 1098         else
 1099                 MNT_IUNLOCK(mp);
 1100         if ((error = VFS_SYNC(mp, MNT_SUSPEND, td)) != 0)
 1101                 vfs_write_resume(mp);
 1102         return (error);
 1103 }
 1104 
 1105 /*
 1106  * Request a filesystem to resume write operations.
 1107  */
 1108 void
 1109 vfs_write_resume(mp)
 1110         struct mount *mp;
 1111 {
 1112 
 1113         MNT_ILOCK(mp);
 1114         if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0) {
 1115                 mp->mnt_kern_flag &= ~(MNTK_SUSPEND | MNTK_SUSPEND2 |
 1116                                        MNTK_SUSPENDED);
 1117                 wakeup(&mp->mnt_writeopcount);
 1118                 wakeup(&mp->mnt_flag);
 1119         }
 1120         MNT_IUNLOCK(mp);
 1121 }
 1122 
 1123 /*
 1124  * Implement kqueues for files by translating it to vnode operation.
 1125  */
 1126 static int
 1127 vn_kqfilter(struct file *fp, struct knote *kn)
 1128 {
 1129         int vfslocked;
 1130         int error;
 1131 
 1132         vfslocked = VFS_LOCK_GIANT(fp->f_vnode->v_mount);
 1133         error = VOP_KQFILTER(fp->f_vnode, kn);
 1134         VFS_UNLOCK_GIANT(vfslocked);
 1135 
 1136         return error;
 1137 }
 1138 
 1139 /*
 1140  * Simplified in-kernel wrapper calls for extended attribute access.
 1141  * Both calls pass in a NULL credential, authorizing as "kernel" access.
 1142  * Set IO_NODELOCKED in ioflg if the vnode is already locked.
 1143  */
 1144 int
 1145 vn_extattr_get(struct vnode *vp, int ioflg, int attrnamespace,
 1146     const char *attrname, int *buflen, char *buf, struct thread *td)
 1147 {
 1148         struct uio      auio;
 1149         struct iovec    iov;
 1150         int     error;
 1151 
 1152         iov.iov_len = *buflen;
 1153         iov.iov_base = buf;
 1154 
 1155         auio.uio_iov = &iov;
 1156         auio.uio_iovcnt = 1;
 1157         auio.uio_rw = UIO_READ;
 1158         auio.uio_segflg = UIO_SYSSPACE;
 1159         auio.uio_td = td;
 1160         auio.uio_offset = 0;
 1161         auio.uio_resid = *buflen;
 1162 
 1163         if ((ioflg & IO_NODELOCKED) == 0)
 1164                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1165 
 1166         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
 1167 
 1168         /* authorize attribute retrieval as kernel */
 1169         error = VOP_GETEXTATTR(vp, attrnamespace, attrname, &auio, NULL, NULL,
 1170             td);
 1171 
 1172         if ((ioflg & IO_NODELOCKED) == 0)
 1173                 VOP_UNLOCK(vp, 0, td);
 1174 
 1175         if (error == 0) {
 1176                 *buflen = *buflen - auio.uio_resid;
 1177         }
 1178 
 1179         return (error);
 1180 }
 1181 
 1182 /*
 1183  * XXX failure mode if partially written?
 1184  */
 1185 int
 1186 vn_extattr_set(struct vnode *vp, int ioflg, int attrnamespace,
 1187     const char *attrname, int buflen, char *buf, struct thread *td)
 1188 {
 1189         struct uio      auio;
 1190         struct iovec    iov;
 1191         struct mount    *mp;
 1192         int     error;
 1193 
 1194         iov.iov_len = buflen;
 1195         iov.iov_base = buf;
 1196 
 1197         auio.uio_iov = &iov;
 1198         auio.uio_iovcnt = 1;
 1199         auio.uio_rw = UIO_WRITE;
 1200         auio.uio_segflg = UIO_SYSSPACE;
 1201         auio.uio_td = td;
 1202         auio.uio_offset = 0;
 1203         auio.uio_resid = buflen;
 1204 
 1205         if ((ioflg & IO_NODELOCKED) == 0) {
 1206                 if ((error = vn_start_write(vp, &mp, V_WAIT)) != 0)
 1207                         return (error);
 1208                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1209         }
 1210 
 1211         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
 1212 
 1213         /* authorize attribute setting as kernel */
 1214         error = VOP_SETEXTATTR(vp, attrnamespace, attrname, &auio, NULL, td);
 1215 
 1216         if ((ioflg & IO_NODELOCKED) == 0) {
 1217                 vn_finished_write(mp);
 1218                 VOP_UNLOCK(vp, 0, td);
 1219         }
 1220 
 1221         return (error);
 1222 }
 1223 
 1224 int
 1225 vn_extattr_rm(struct vnode *vp, int ioflg, int attrnamespace,
 1226     const char *attrname, struct thread *td)
 1227 {
 1228         struct mount    *mp;
 1229         int     error;
 1230 
 1231         if ((ioflg & IO_NODELOCKED) == 0) {
 1232                 if ((error = vn_start_write(vp, &mp, V_WAIT)) != 0)
 1233                         return (error);
 1234                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1235         }
 1236 
 1237         ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
 1238 
 1239         /* authorize attribute removal as kernel */
 1240         error = VOP_DELETEEXTATTR(vp, attrnamespace, attrname, NULL, td);
 1241         if (error == EOPNOTSUPP)
 1242                 error = VOP_SETEXTATTR(vp, attrnamespace, attrname, NULL,
 1243                     NULL, td);
 1244 
 1245         if ((ioflg & IO_NODELOCKED) == 0) {
 1246                 vn_finished_write(mp);
 1247                 VOP_UNLOCK(vp, 0, td);
 1248         }
 1249 
 1250         return (error);
 1251 }

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