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

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    1 /* $FreeBSD$ */
    2 /*      $NetBSD: msdosfs_vnops.c,v 1.68 1998/02/10 14:10:04 mrg Exp $   */
    3 
    4 /*-
    5  * SPDX-License-Identifier: BSD-4-Clause
    6  *
    7  * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
    8  * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
    9  * All rights reserved.
   10  * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
   11  *
   12  * Redistribution and use in source and binary forms, with or without
   13  * modification, are permitted provided that the following conditions
   14  * are met:
   15  * 1. Redistributions of source code must retain the above copyright
   16  *    notice, this list of conditions and the following disclaimer.
   17  * 2. Redistributions in binary form must reproduce the above copyright
   18  *    notice, this list of conditions and the following disclaimer in the
   19  *    documentation and/or other materials provided with the distribution.
   20  * 3. All advertising materials mentioning features or use of this software
   21  *    must display the following acknowledgement:
   22  *      This product includes software developed by TooLs GmbH.
   23  * 4. The name of TooLs GmbH may not be used to endorse or promote products
   24  *    derived from this software without specific prior written permission.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
   27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   29  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   31  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
   32  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   33  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
   34  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   35  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   36  */
   37 /*-
   38  * Written by Paul Popelka (paulp@uts.amdahl.com)
   39  *
   40  * You can do anything you want with this software, just don't say you wrote
   41  * it, and don't remove this notice.
   42  *
   43  * This software is provided "as is".
   44  *
   45  * The author supplies this software to be publicly redistributed on the
   46  * understanding that the author is not responsible for the correct
   47  * functioning of this software in any circumstances and is not liable for
   48  * any damages caused by this software.
   49  *
   50  * October 1992
   51  */
   52 
   53 #include <sys/param.h>
   54 #include <sys/systm.h>
   55 #include <sys/bio.h>
   56 #include <sys/buf.h>
   57 #include <sys/clock.h>
   58 #include <sys/dirent.h>
   59 #include <sys/lock.h>
   60 #include <sys/lockf.h>
   61 #include <sys/malloc.h>
   62 #include <sys/mount.h>
   63 #include <sys/mutex.h>
   64 #include <sys/namei.h>
   65 #include <sys/priv.h>
   66 #include <sys/stat.h>
   67 #include <sys/sysctl.h>
   68 #include <sys/unistd.h>
   69 #include <sys/vmmeter.h>
   70 #include <sys/vnode.h>
   71 
   72 #include <vm/vm.h>
   73 #include <vm/vm_extern.h>
   74 #include <vm/vnode_pager.h>
   75 
   76 #include <fs/msdosfs/bpb.h>
   77 #include <fs/msdosfs/direntry.h>
   78 #include <fs/msdosfs/denode.h>
   79 #include <fs/msdosfs/fat.h>
   80 #include <fs/msdosfs/msdosfsmount.h>
   81 
   82 /*
   83  * Prototypes for MSDOSFS vnode operations
   84  */
   85 static vop_create_t     msdosfs_create;
   86 static vop_mknod_t      msdosfs_mknod;
   87 static vop_open_t       msdosfs_open;
   88 static vop_close_t      msdosfs_close;
   89 static vop_access_t     msdosfs_access;
   90 static vop_getattr_t    msdosfs_getattr;
   91 static vop_setattr_t    msdosfs_setattr;
   92 static vop_read_t       msdosfs_read;
   93 static vop_write_t      msdosfs_write;
   94 static vop_fsync_t      msdosfs_fsync;
   95 static vop_remove_t     msdosfs_remove;
   96 static vop_link_t       msdosfs_link;
   97 static vop_rename_t     msdosfs_rename;
   98 static vop_mkdir_t      msdosfs_mkdir;
   99 static vop_rmdir_t      msdosfs_rmdir;
  100 static vop_symlink_t    msdosfs_symlink;
  101 static vop_readdir_t    msdosfs_readdir;
  102 static vop_bmap_t       msdosfs_bmap;
  103 static vop_getpages_t   msdosfs_getpages;
  104 static vop_strategy_t   msdosfs_strategy;
  105 static vop_print_t      msdosfs_print;
  106 static vop_pathconf_t   msdosfs_pathconf;
  107 static vop_vptofh_t     msdosfs_vptofh;
  108 
  109 /*
  110  * Some general notes:
  111  *
  112  * In the ufs filesystem the inodes, superblocks, and indirect blocks are
  113  * read/written using the vnode for the filesystem. Blocks that represent
  114  * the contents of a file are read/written using the vnode for the file
  115  * (including directories when they are read/written as files). This
  116  * presents problems for the dos filesystem because data that should be in
  117  * an inode (if dos had them) resides in the directory itself.  Since we
  118  * must update directory entries without the benefit of having the vnode
  119  * for the directory we must use the vnode for the filesystem.  This means
  120  * that when a directory is actually read/written (via read, write, or
  121  * readdir, or seek) we must use the vnode for the filesystem instead of
  122  * the vnode for the directory as would happen in ufs. This is to insure we
  123  * retrieve the correct block from the buffer cache since the hash value is
  124  * based upon the vnode address and the desired block number.
  125  */
  126 
  127 /*
  128  * Create a regular file. On entry the directory to contain the file being
  129  * created is locked.  We must release before we return. We must also free
  130  * the pathname buffer pointed at by cnp->cn_pnbuf, always on error, or
  131  * only if the SAVESTART bit in cn_flags is clear on success.
  132  */
  133 static int
  134 msdosfs_create(struct vop_create_args *ap)
  135 {
  136         struct componentname *cnp = ap->a_cnp;
  137         struct denode ndirent;
  138         struct denode *dep;
  139         struct denode *pdep = VTODE(ap->a_dvp);
  140         struct timespec ts;
  141         int error;
  142 
  143 #ifdef MSDOSFS_DEBUG
  144         printf("msdosfs_create(cnp %p, vap %p\n", cnp, ap->a_vap);
  145 #endif
  146 
  147         /*
  148          * If this is the root directory and there is no space left we
  149          * can't do anything.  This is because the root directory can not
  150          * change size.
  151          */
  152         if (pdep->de_StartCluster == MSDOSFSROOT
  153             && pdep->de_fndoffset >= pdep->de_FileSize) {
  154                 error = ENOSPC;
  155                 goto bad;
  156         }
  157 
  158         /*
  159          * Create a directory entry for the file, then call createde() to
  160          * have it installed. NOTE: DOS files are always executable.  We
  161          * use the absence of the owner write bit to make the file
  162          * readonly.
  163          */
  164 #ifdef DIAGNOSTIC
  165         if ((cnp->cn_flags & HASBUF) == 0)
  166                 panic("msdosfs_create: no name");
  167 #endif
  168         memset(&ndirent, 0, sizeof(ndirent));
  169         error = uniqdosname(pdep, cnp, ndirent.de_Name);
  170         if (error)
  171                 goto bad;
  172 
  173         ndirent.de_Attributes = ATTR_ARCHIVE;
  174         ndirent.de_LowerCase = 0;
  175         ndirent.de_StartCluster = 0;
  176         ndirent.de_FileSize = 0;
  177         ndirent.de_pmp = pdep->de_pmp;
  178         ndirent.de_flag = DE_ACCESS | DE_CREATE | DE_UPDATE;
  179         vfs_timestamp(&ts);
  180         DETIMES(&ndirent, &ts, &ts, &ts);
  181         error = createde(&ndirent, pdep, &dep, cnp);
  182         if (error)
  183                 goto bad;
  184         *ap->a_vpp = DETOV(dep);
  185         if ((cnp->cn_flags & MAKEENTRY) != 0)
  186                 cache_enter(ap->a_dvp, *ap->a_vpp, cnp);
  187         return (0);
  188 
  189 bad:
  190         return (error);
  191 }
  192 
  193 static int
  194 msdosfs_mknod(struct vop_mknod_args *ap)
  195 {
  196 
  197     return (EINVAL);
  198 }
  199 
  200 static int
  201 msdosfs_open(struct vop_open_args *ap)
  202 {
  203         struct denode *dep = VTODE(ap->a_vp);
  204         vnode_create_vobject(ap->a_vp, dep->de_FileSize, ap->a_td);
  205         return 0;
  206 }
  207 
  208 static int
  209 msdosfs_close(struct vop_close_args *ap)
  210 {
  211         struct vnode *vp = ap->a_vp;
  212         struct denode *dep = VTODE(vp);
  213         struct timespec ts;
  214 
  215         VI_LOCK(vp);
  216         if (vp->v_usecount > 1) {
  217                 vfs_timestamp(&ts);
  218                 DETIMES(dep, &ts, &ts, &ts);
  219         }
  220         VI_UNLOCK(vp);
  221         return 0;
  222 }
  223 
  224 static int
  225 msdosfs_access(struct vop_access_args *ap)
  226 {
  227         struct vnode *vp = ap->a_vp;
  228         struct denode *dep = VTODE(ap->a_vp);
  229         struct msdosfsmount *pmp = dep->de_pmp;
  230         mode_t file_mode;
  231         accmode_t accmode = ap->a_accmode;
  232 
  233         file_mode = S_IRWXU|S_IRWXG|S_IRWXO;
  234         file_mode &= (vp->v_type == VDIR ? pmp->pm_dirmask : pmp->pm_mask);
  235 
  236         /*
  237          * Disallow writing to directories and regular files if the
  238          * filesystem is read-only.
  239          */
  240         if (accmode & VWRITE) {
  241                 switch (vp->v_type) {
  242                 case VREG:
  243                 case VDIR:
  244                         if (vp->v_mount->mnt_flag & MNT_RDONLY)
  245                                 return (EROFS);
  246                         break;
  247                 default:
  248                         break;
  249                 }
  250         }
  251 
  252         return (vaccess(vp->v_type, file_mode, pmp->pm_uid, pmp->pm_gid,
  253             ap->a_accmode, ap->a_cred, NULL));
  254 }
  255 
  256 static int
  257 msdosfs_getattr(struct vop_getattr_args *ap)
  258 {
  259         struct denode *dep = VTODE(ap->a_vp);
  260         struct msdosfsmount *pmp = dep->de_pmp;
  261         struct vattr *vap = ap->a_vap;
  262         mode_t mode;
  263         struct timespec ts;
  264         u_long dirsperblk = pmp->pm_BytesPerSec / sizeof(struct direntry);
  265         uint64_t fileid;
  266 
  267         vfs_timestamp(&ts);
  268         DETIMES(dep, &ts, &ts, &ts);
  269         vap->va_fsid = dev2udev(pmp->pm_dev);
  270         /*
  271          * The following computation of the fileid must be the same as that
  272          * used in msdosfs_readdir() to compute d_fileno. If not, pwd
  273          * doesn't work.
  274          */
  275         if (dep->de_Attributes & ATTR_DIRECTORY) {
  276                 fileid = (uint64_t)cntobn(pmp, dep->de_StartCluster) *
  277                     dirsperblk;
  278                 if (dep->de_StartCluster == MSDOSFSROOT)
  279                         fileid = 1;
  280         } else {
  281                 fileid = (uint64_t)cntobn(pmp, dep->de_dirclust) *
  282                     dirsperblk;
  283                 if (dep->de_dirclust == MSDOSFSROOT)
  284                         fileid = (uint64_t)roottobn(pmp, 0) * dirsperblk;
  285                 fileid += (uoff_t)dep->de_diroffset / sizeof(struct direntry);
  286         }
  287         vap->va_fileid = fileid;
  288 
  289         mode = S_IRWXU|S_IRWXG|S_IRWXO;
  290         if (dep->de_Attributes & ATTR_READONLY)
  291                 mode &= ~(S_IWUSR|S_IWGRP|S_IWOTH);
  292         vap->va_mode = mode &
  293             (ap->a_vp->v_type == VDIR ? pmp->pm_dirmask : pmp->pm_mask);
  294         vap->va_uid = pmp->pm_uid;
  295         vap->va_gid = pmp->pm_gid;
  296         vap->va_nlink = 1;
  297         vap->va_rdev = NODEV;
  298         vap->va_size = dep->de_FileSize;
  299         fattime2timespec(dep->de_MDate, dep->de_MTime, 0, 0, &vap->va_mtime);
  300         vap->va_ctime = vap->va_mtime;
  301         if (pmp->pm_flags & MSDOSFSMNT_LONGNAME) {
  302                 fattime2timespec(dep->de_ADate, 0, 0, 0, &vap->va_atime);
  303                 fattime2timespec(dep->de_CDate, dep->de_CTime, dep->de_CHun,
  304                     0, &vap->va_birthtime);
  305         } else {
  306                 vap->va_atime = vap->va_mtime;
  307                 vap->va_birthtime.tv_sec = -1;
  308                 vap->va_birthtime.tv_nsec = 0;
  309         }
  310         vap->va_flags = 0;
  311         if (dep->de_Attributes & ATTR_ARCHIVE)
  312                 vap->va_flags |= UF_ARCHIVE;
  313         if (dep->de_Attributes & ATTR_HIDDEN)
  314                 vap->va_flags |= UF_HIDDEN;
  315         if (dep->de_Attributes & ATTR_READONLY)
  316                 vap->va_flags |= UF_READONLY;
  317         if (dep->de_Attributes & ATTR_SYSTEM)
  318                 vap->va_flags |= UF_SYSTEM;
  319         vap->va_gen = 0;
  320         vap->va_blocksize = pmp->pm_bpcluster;
  321         vap->va_bytes =
  322             (dep->de_FileSize + pmp->pm_crbomask) & ~pmp->pm_crbomask;
  323         vap->va_type = ap->a_vp->v_type;
  324         vap->va_filerev = dep->de_modrev;
  325         return (0);
  326 }
  327 
  328 static int
  329 msdosfs_setattr(struct vop_setattr_args *ap)
  330 {
  331         struct vnode *vp = ap->a_vp;
  332         struct denode *dep = VTODE(ap->a_vp);
  333         struct msdosfsmount *pmp = dep->de_pmp;
  334         struct vattr *vap = ap->a_vap;
  335         struct ucred *cred = ap->a_cred;
  336         struct thread *td = curthread;
  337         int error = 0;
  338 
  339 #ifdef MSDOSFS_DEBUG
  340         printf("msdosfs_setattr(): vp %p, vap %p, cred %p\n",
  341             ap->a_vp, vap, cred);
  342 #endif
  343 
  344         /*
  345          * Check for unsettable attributes.
  346          */
  347         if ((vap->va_type != VNON) || (vap->va_nlink != VNOVAL) ||
  348             (vap->va_fsid != VNOVAL) || (vap->va_fileid != VNOVAL) ||
  349             (vap->va_blocksize != VNOVAL) || (vap->va_rdev != VNOVAL) ||
  350             (vap->va_bytes != VNOVAL) || (vap->va_gen != VNOVAL)) {
  351 #ifdef MSDOSFS_DEBUG
  352                 printf("msdosfs_setattr(): returning EINVAL\n");
  353                 printf("    va_type %d, va_nlink %llx, va_fsid %llx, va_fileid %llx\n",
  354                     vap->va_type, (unsigned long long)vap->va_nlink,
  355                     (unsigned long long)vap->va_fsid,
  356                     (unsigned long long)vap->va_fileid);
  357                 printf("    va_blocksize %lx, va_rdev %llx, va_bytes %llx, va_gen %lx\n",
  358                     vap->va_blocksize, (unsigned long long)vap->va_rdev,
  359                     (unsigned long long)vap->va_bytes, vap->va_gen);
  360                 printf("    va_uid %x, va_gid %x\n",
  361                     vap->va_uid, vap->va_gid);
  362 #endif
  363                 return (EINVAL);
  364         }
  365 
  366         /*
  367          * We don't allow setting attributes on the root directory.
  368          * The special case for the root directory is because before
  369          * FAT32, the root directory didn't have an entry for itself
  370          * (and was otherwise special).  With FAT32, the root
  371          * directory is not so special, but still doesn't have an
  372          * entry for itself.
  373          */
  374         if (vp->v_vflag & VV_ROOT)
  375                 return (EINVAL);
  376 
  377         if (vap->va_flags != VNOVAL) {
  378                 if (vp->v_mount->mnt_flag & MNT_RDONLY)
  379                         return (EROFS);
  380                 if (cred->cr_uid != pmp->pm_uid) {
  381                         error = priv_check_cred(cred, PRIV_VFS_ADMIN, 0);
  382                         if (error)
  383                                 return (error);
  384                 }
  385                 /*
  386                  * We are very inconsistent about handling unsupported
  387                  * attributes.  We ignored the access time and the
  388                  * read and execute bits.  We were strict for the other
  389                  * attributes.
  390                  */
  391                 if (vap->va_flags & ~(UF_ARCHIVE | UF_HIDDEN | UF_READONLY |
  392                     UF_SYSTEM))
  393                         return EOPNOTSUPP;
  394                 if (vap->va_flags & UF_ARCHIVE)
  395                         dep->de_Attributes |= ATTR_ARCHIVE;
  396                 else
  397                         dep->de_Attributes &= ~ATTR_ARCHIVE;
  398                 if (vap->va_flags & UF_HIDDEN)
  399                         dep->de_Attributes |= ATTR_HIDDEN;
  400                 else
  401                         dep->de_Attributes &= ~ATTR_HIDDEN;
  402                 /* We don't allow changing the readonly bit on directories. */
  403                 if (vp->v_type != VDIR) {
  404                         if (vap->va_flags & UF_READONLY)
  405                                 dep->de_Attributes |= ATTR_READONLY;
  406                         else
  407                                 dep->de_Attributes &= ~ATTR_READONLY;
  408                 }
  409                 if (vap->va_flags & UF_SYSTEM)
  410                         dep->de_Attributes |= ATTR_SYSTEM;
  411                 else
  412                         dep->de_Attributes &= ~ATTR_SYSTEM;
  413                 dep->de_flag |= DE_MODIFIED;
  414         }
  415 
  416         if (vap->va_uid != (uid_t)VNOVAL || vap->va_gid != (gid_t)VNOVAL) {
  417                 uid_t uid;
  418                 gid_t gid;
  419 
  420                 if (vp->v_mount->mnt_flag & MNT_RDONLY)
  421                         return (EROFS);
  422                 uid = vap->va_uid;
  423                 if (uid == (uid_t)VNOVAL)
  424                         uid = pmp->pm_uid;
  425                 gid = vap->va_gid;
  426                 if (gid == (gid_t)VNOVAL)
  427                         gid = pmp->pm_gid;
  428                 if (cred->cr_uid != pmp->pm_uid || uid != pmp->pm_uid ||
  429                     (gid != pmp->pm_gid && !groupmember(gid, cred))) {
  430                         error = priv_check_cred(cred, PRIV_VFS_CHOWN, 0);
  431                         if (error)
  432                                 return (error);
  433                 }
  434                 if (uid != pmp->pm_uid || gid != pmp->pm_gid)
  435                         return EINVAL;
  436         }
  437 
  438         if (vap->va_size != VNOVAL) {
  439                 switch (vp->v_type) {
  440                 case VDIR:
  441                         return (EISDIR);
  442                 case VREG:
  443                         /*
  444                          * Truncation is only supported for regular files,
  445                          * Disallow it if the filesystem is read-only.
  446                          */
  447                         if (vp->v_mount->mnt_flag & MNT_RDONLY)
  448                                 return (EROFS);
  449                         break;
  450                 default:
  451                         /*
  452                          * According to POSIX, the result is unspecified
  453                          * for file types other than regular files,
  454                          * directories and shared memory objects.  We
  455                          * don't support any file types except regular
  456                          * files and directories in this file system, so
  457                          * this (default) case is unreachable and can do
  458                          * anything.  Keep falling through to detrunc()
  459                          * for now.
  460                          */
  461                         break;
  462                 }
  463                 error = detrunc(dep, vap->va_size, 0, cred);
  464                 if (error)
  465                         return error;
  466         }
  467         if (vap->va_atime.tv_sec != VNOVAL || vap->va_mtime.tv_sec != VNOVAL) {
  468                 if (vp->v_mount->mnt_flag & MNT_RDONLY)
  469                         return (EROFS);
  470                 error = vn_utimes_perm(vp, vap, cred, td);
  471                 if (error != 0)
  472                         return (error);
  473                 if ((pmp->pm_flags & MSDOSFSMNT_NOWIN95) == 0 &&
  474                     vap->va_atime.tv_sec != VNOVAL) {
  475                         dep->de_flag &= ~DE_ACCESS;
  476                         timespec2fattime(&vap->va_atime, 0,
  477                             &dep->de_ADate, NULL, NULL);
  478                 }
  479                 if (vap->va_mtime.tv_sec != VNOVAL) {
  480                         dep->de_flag &= ~DE_UPDATE;
  481                         timespec2fattime(&vap->va_mtime, 0,
  482                             &dep->de_MDate, &dep->de_MTime, NULL);
  483                 }
  484                 /*
  485                  * We don't set the archive bit when modifying the time of
  486                  * a directory to emulate the Windows/DOS behavior.
  487                  */
  488                 if (vp->v_type != VDIR)
  489                         dep->de_Attributes |= ATTR_ARCHIVE;
  490                 dep->de_flag |= DE_MODIFIED;
  491         }
  492         /*
  493          * DOS files only have the ability to have their writability
  494          * attribute set, so we use the owner write bit to set the readonly
  495          * attribute.
  496          */
  497         if (vap->va_mode != (mode_t)VNOVAL) {
  498                 if (vp->v_mount->mnt_flag & MNT_RDONLY)
  499                         return (EROFS);
  500                 if (cred->cr_uid != pmp->pm_uid) {
  501                         error = priv_check_cred(cred, PRIV_VFS_ADMIN, 0);
  502                         if (error)
  503                                 return (error);
  504                 }
  505                 if (vp->v_type != VDIR) {
  506                         /* We ignore the read and execute bits. */
  507                         if (vap->va_mode & S_IWUSR)
  508                                 dep->de_Attributes &= ~ATTR_READONLY;
  509                         else
  510                                 dep->de_Attributes |= ATTR_READONLY;
  511                         dep->de_Attributes |= ATTR_ARCHIVE;
  512                         dep->de_flag |= DE_MODIFIED;
  513                 }
  514         }
  515         return (deupdat(dep, 0));
  516 }
  517 
  518 static int
  519 msdosfs_read(struct vop_read_args *ap)
  520 {
  521         int error = 0;
  522         int blsize;
  523         int isadir;
  524         ssize_t orig_resid;
  525         u_int n;
  526         u_long diff;
  527         u_long on;
  528         daddr_t lbn;
  529         daddr_t rablock;
  530         int rasize;
  531         int seqcount;
  532         struct buf *bp;
  533         struct vnode *vp = ap->a_vp;
  534         struct denode *dep = VTODE(vp);
  535         struct msdosfsmount *pmp = dep->de_pmp;
  536         struct uio *uio = ap->a_uio;
  537 
  538         /*
  539          * If they didn't ask for any data, then we are done.
  540          */
  541         orig_resid = uio->uio_resid;
  542         if (orig_resid == 0)
  543                 return (0);
  544 
  545         /*
  546          * The caller is supposed to ensure that
  547          * uio->uio_offset >= 0 and uio->uio_resid >= 0.
  548          * We don't need to check for large offsets as in ffs because
  549          * dep->de_FileSize <= MSDOSFS_FILESIZE_MAX < OFF_MAX, so large
  550          * offsets cannot cause overflow even in theory.
  551          */
  552 
  553         seqcount = ap->a_ioflag >> IO_SEQSHIFT;
  554 
  555         isadir = dep->de_Attributes & ATTR_DIRECTORY;
  556         do {
  557                 if (uio->uio_offset >= dep->de_FileSize)
  558                         break;
  559                 lbn = de_cluster(pmp, uio->uio_offset);
  560                 rablock = lbn + 1;
  561                 blsize = pmp->pm_bpcluster;
  562                 on = uio->uio_offset & pmp->pm_crbomask;
  563                 /*
  564                  * If we are operating on a directory file then be sure to
  565                  * do i/o with the vnode for the filesystem instead of the
  566                  * vnode for the directory.
  567                  */
  568                 if (isadir) {
  569                         /* convert cluster # to block # */
  570                         error = pcbmap(dep, lbn, &lbn, 0, &blsize);
  571                         if (error == E2BIG) {
  572                                 error = EINVAL;
  573                                 break;
  574                         } else if (error)
  575                                 break;
  576                         error = bread(pmp->pm_devvp, lbn, blsize, NOCRED, &bp);
  577                 } else if (de_cn2off(pmp, rablock) >= dep->de_FileSize) {
  578                         error = bread(vp, lbn, blsize, NOCRED, &bp);
  579                 } else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
  580                         error = cluster_read(vp, dep->de_FileSize, lbn, blsize,
  581                             NOCRED, on + uio->uio_resid, seqcount, 0, &bp);
  582                 } else if (seqcount > 1) {
  583                         rasize = blsize;
  584                         error = breadn(vp, lbn,
  585                             blsize, &rablock, &rasize, 1, NOCRED, &bp);
  586                 } else {
  587                         error = bread(vp, lbn, blsize, NOCRED, &bp);
  588                 }
  589                 if (error) {
  590                         brelse(bp);
  591                         break;
  592                 }
  593                 diff = pmp->pm_bpcluster - on;
  594                 n = diff > uio->uio_resid ? uio->uio_resid : diff;
  595                 diff = dep->de_FileSize - uio->uio_offset;
  596                 if (diff < n)
  597                         n = diff;
  598                 diff = blsize - bp->b_resid;
  599                 if (diff < n)
  600                         n = diff;
  601                 error = vn_io_fault_uiomove(bp->b_data + on, (int) n, uio);
  602                 brelse(bp);
  603         } while (error == 0 && uio->uio_resid > 0 && n != 0);
  604         if (!isadir && (error == 0 || uio->uio_resid != orig_resid) &&
  605             (vp->v_mount->mnt_flag & (MNT_NOATIME | MNT_RDONLY)) == 0)
  606                 dep->de_flag |= DE_ACCESS;
  607         return (error);
  608 }
  609 
  610 /*
  611  * Write data to a file or directory.
  612  */
  613 static int
  614 msdosfs_write(struct vop_write_args *ap)
  615 {
  616         int n;
  617         int croffset;
  618         ssize_t resid;
  619         u_long osize;
  620         int error = 0;
  621         u_long count;
  622         int seqcount;
  623         daddr_t bn, lastcn;
  624         struct buf *bp;
  625         int ioflag = ap->a_ioflag;
  626         struct uio *uio = ap->a_uio;
  627         struct vnode *vp = ap->a_vp;
  628         struct vnode *thisvp;
  629         struct denode *dep = VTODE(vp);
  630         struct msdosfsmount *pmp = dep->de_pmp;
  631         struct ucred *cred = ap->a_cred;
  632 
  633 #ifdef MSDOSFS_DEBUG
  634         printf("msdosfs_write(vp %p, uio %p, ioflag %x, cred %p\n",
  635             vp, uio, ioflag, cred);
  636         printf("msdosfs_write(): diroff %lu, dirclust %lu, startcluster %lu\n",
  637             dep->de_diroffset, dep->de_dirclust, dep->de_StartCluster);
  638 #endif
  639 
  640         switch (vp->v_type) {
  641         case VREG:
  642                 if (ioflag & IO_APPEND)
  643                         uio->uio_offset = dep->de_FileSize;
  644                 thisvp = vp;
  645                 break;
  646         case VDIR:
  647                 return EISDIR;
  648         default:
  649                 panic("msdosfs_write(): bad file type");
  650         }
  651 
  652         /*
  653          * This is needed (unlike in ffs_write()) because we extend the
  654          * file outside of the loop but we don't want to extend the file
  655          * for writes of 0 bytes.
  656          */
  657         if (uio->uio_resid == 0)
  658                 return (0);
  659 
  660         /*
  661          * The caller is supposed to ensure that
  662          * uio->uio_offset >= 0 and uio->uio_resid >= 0.
  663          */
  664         if ((uoff_t)uio->uio_offset + uio->uio_resid > MSDOSFS_FILESIZE_MAX)
  665                 return (EFBIG);
  666 
  667         /*
  668          * If they've exceeded their filesize limit, tell them about it.
  669          */
  670         if (vn_rlimit_fsize(vp, uio, uio->uio_td))
  671                 return (EFBIG);
  672 
  673         /*
  674          * If the offset we are starting the write at is beyond the end of
  675          * the file, then they've done a seek.  Unix filesystems allow
  676          * files with holes in them, DOS doesn't so we must fill the hole
  677          * with zeroed blocks.
  678          */
  679         if (uio->uio_offset > dep->de_FileSize) {
  680                 error = deextend(dep, uio->uio_offset, cred);
  681                 if (error)
  682                         return (error);
  683         }
  684 
  685         /*
  686          * Remember some values in case the write fails.
  687          */
  688         resid = uio->uio_resid;
  689         osize = dep->de_FileSize;
  690 
  691         /*
  692          * If we write beyond the end of the file, extend it to its ultimate
  693          * size ahead of the time to hopefully get a contiguous area.
  694          */
  695         if (uio->uio_offset + resid > osize) {
  696                 count = de_clcount(pmp, uio->uio_offset + resid) -
  697                         de_clcount(pmp, osize);
  698                 error = extendfile(dep, count, NULL, NULL, 0);
  699                 if (error &&  (error != ENOSPC || (ioflag & IO_UNIT)))
  700                         goto errexit;
  701                 lastcn = dep->de_fc[FC_LASTFC].fc_frcn;
  702         } else
  703                 lastcn = de_clcount(pmp, osize) - 1;
  704 
  705         seqcount = ioflag >> IO_SEQSHIFT;
  706         do {
  707                 if (de_cluster(pmp, uio->uio_offset) > lastcn) {
  708                         error = ENOSPC;
  709                         break;
  710                 }
  711 
  712                 croffset = uio->uio_offset & pmp->pm_crbomask;
  713                 n = min(uio->uio_resid, pmp->pm_bpcluster - croffset);
  714                 if (uio->uio_offset + n > dep->de_FileSize) {
  715                         dep->de_FileSize = uio->uio_offset + n;
  716                         /* The object size needs to be set before buffer is allocated */
  717                         vnode_pager_setsize(vp, dep->de_FileSize);
  718                 }
  719 
  720                 bn = de_cluster(pmp, uio->uio_offset);
  721                 if ((uio->uio_offset & pmp->pm_crbomask) == 0
  722                     && (de_cluster(pmp, uio->uio_offset + uio->uio_resid)
  723                         > de_cluster(pmp, uio->uio_offset)
  724                         || uio->uio_offset + uio->uio_resid >= dep->de_FileSize)) {
  725                         /*
  726                          * If either the whole cluster gets written,
  727                          * or we write the cluster from its start beyond EOF,
  728                          * then no need to read data from disk.
  729                          */
  730                         bp = getblk(thisvp, bn, pmp->pm_bpcluster, 0, 0, 0);
  731                         /*
  732                          * This call to vfs_bio_clrbuf() ensures that
  733                          * even if vn_io_fault_uiomove() below faults,
  734                          * garbage from the newly instantiated buffer
  735                          * is not exposed to the userspace via mmap().
  736                          */
  737                         vfs_bio_clrbuf(bp);
  738                         /*
  739                          * Do the bmap now, since pcbmap needs buffers
  740                          * for the FAT table. (see msdosfs_strategy)
  741                          */
  742                         if (bp->b_blkno == bp->b_lblkno) {
  743                                 error = pcbmap(dep, bp->b_lblkno, &bn, 0, 0);
  744                                 if (error)
  745                                         bp->b_blkno = -1;
  746                                 else
  747                                         bp->b_blkno = bn;
  748                         }
  749                         if (bp->b_blkno == -1) {
  750                                 brelse(bp);
  751                                 if (!error)
  752                                         error = EIO;            /* XXX */
  753                                 break;
  754                         }
  755                 } else {
  756                         /*
  757                          * The block we need to write into exists, so read it in.
  758                          */
  759                         error = bread(thisvp, bn, pmp->pm_bpcluster, cred, &bp);
  760                         if (error) {
  761                                 brelse(bp);
  762                                 break;
  763                         }
  764                 }
  765 
  766                 /*
  767                  * Should these vnode_pager_* functions be done on dir
  768                  * files?
  769                  */
  770 
  771                 /*
  772                  * Copy the data from user space into the buf header.
  773                  */
  774                 error = vn_io_fault_uiomove(bp->b_data + croffset, n, uio);
  775                 if (error) {
  776                         brelse(bp);
  777                         break;
  778                 }
  779 
  780                 /* Prepare for clustered writes in some else clauses. */
  781                 if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERW) == 0)
  782                         bp->b_flags |= B_CLUSTEROK;
  783 
  784                 /*
  785                  * If IO_SYNC, then each buffer is written synchronously.
  786                  * Otherwise, if we have a severe page deficiency then
  787                  * write the buffer asynchronously.  Otherwise, if on a
  788                  * cluster boundary then write the buffer asynchronously,
  789                  * combining it with contiguous clusters if permitted and
  790                  * possible, since we don't expect more writes into this
  791                  * buffer soon.  Otherwise, do a delayed write because we
  792                  * expect more writes into this buffer soon.
  793                  */
  794                 if (ioflag & IO_SYNC)
  795                         (void)bwrite(bp);
  796                 else if (vm_page_count_severe() || buf_dirty_count_severe())
  797                         bawrite(bp);
  798                 else if (n + croffset == pmp->pm_bpcluster) {
  799                         if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERW) == 0)
  800                                 cluster_write(vp, bp, dep->de_FileSize,
  801                                     seqcount, 0);
  802                         else
  803                                 bawrite(bp);
  804                 } else
  805                         bdwrite(bp);
  806                 dep->de_flag |= DE_UPDATE;
  807         } while (error == 0 && uio->uio_resid > 0);
  808 
  809         /*
  810          * If the write failed and they want us to, truncate the file back
  811          * to the size it was before the write was attempted.
  812          */
  813 errexit:
  814         if (error) {
  815                 if (ioflag & IO_UNIT) {
  816                         detrunc(dep, osize, ioflag & IO_SYNC, NOCRED);
  817                         uio->uio_offset -= resid - uio->uio_resid;
  818                         uio->uio_resid = resid;
  819                 } else {
  820                         detrunc(dep, dep->de_FileSize, ioflag & IO_SYNC, NOCRED);
  821                         if (uio->uio_resid != resid)
  822                                 error = 0;
  823                 }
  824         } else if (ioflag & IO_SYNC)
  825                 error = deupdat(dep, 1);
  826         return (error);
  827 }
  828 
  829 /*
  830  * Flush the blocks of a file to disk.
  831  */
  832 static int
  833 msdosfs_fsync(struct vop_fsync_args *ap)
  834 {
  835         struct vnode *devvp;
  836         int allerror, error;
  837 
  838         vop_stdfsync(ap);
  839 
  840         /*
  841         * If the syncing request comes from fsync(2), sync the entire
  842         * FAT and any other metadata that happens to be on devvp.  We
  843         * need this mainly for the FAT.  We write the FAT sloppily, and
  844         * syncing it all now is the best we can easily do to get all
  845         * directory entries associated with the file (not just the file)
  846         * fully synced.  The other metadata includes critical metadata
  847         * for all directory entries, but only in the MNT_ASYNC case.  We
  848         * will soon sync all metadata in the file's directory entry.
  849         * Non-critical metadata for associated directory entries only
  850         * gets synced accidentally, as in most file systems.
  851         */
  852         if (ap->a_waitfor != MNT_NOWAIT) {
  853                 devvp = VTODE(ap->a_vp)->de_pmp->pm_devvp;
  854                 vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
  855                 allerror = VOP_FSYNC(devvp, MNT_WAIT, ap->a_td);
  856                 VOP_UNLOCK(devvp, 0);
  857         } else
  858                 allerror = 0;
  859 
  860         error = deupdat(VTODE(ap->a_vp), ap->a_waitfor != MNT_NOWAIT);
  861         if (allerror == 0)
  862                 allerror = error;
  863         return (allerror);
  864 }
  865 
  866 static int
  867 msdosfs_remove(struct vop_remove_args *ap)
  868 {
  869         struct denode *dep = VTODE(ap->a_vp);
  870         struct denode *ddep = VTODE(ap->a_dvp);
  871         int error;
  872 
  873         if (ap->a_vp->v_type == VDIR)
  874                 error = EPERM;
  875         else
  876                 error = removede(ddep, dep);
  877 #ifdef MSDOSFS_DEBUG
  878         printf("msdosfs_remove(), dep %p, v_usecount %d\n", dep, ap->a_vp->v_usecount);
  879 #endif
  880         return (error);
  881 }
  882 
  883 /*
  884  * DOS filesystems don't know what links are.
  885  */
  886 static int
  887 msdosfs_link(struct vop_link_args *ap)
  888 {
  889         return (EOPNOTSUPP);
  890 }
  891 
  892 /*
  893  * Renames on files require moving the denode to a new hash queue since the
  894  * denode's location is used to compute which hash queue to put the file
  895  * in. Unless it is a rename in place.  For example "mv a b".
  896  *
  897  * What follows is the basic algorithm:
  898  *
  899  * if (file move) {
  900  *      if (dest file exists) {
  901  *              remove dest file
  902  *      }
  903  *      if (dest and src in same directory) {
  904  *              rewrite name in existing directory slot
  905  *      } else {
  906  *              write new entry in dest directory
  907  *              update offset and dirclust in denode
  908  *              move denode to new hash chain
  909  *              clear old directory entry
  910  *      }
  911  * } else {
  912  *      directory move
  913  *      if (dest directory exists) {
  914  *              if (dest is not empty) {
  915  *                      return ENOTEMPTY
  916  *              }
  917  *              remove dest directory
  918  *      }
  919  *      if (dest and src in same directory) {
  920  *              rewrite name in existing entry
  921  *      } else {
  922  *              be sure dest is not a child of src directory
  923  *              write entry in dest directory
  924  *              update "." and ".." in moved directory
  925  *              clear old directory entry for moved directory
  926  *      }
  927  * }
  928  *
  929  * On entry:
  930  *      source's parent directory is unlocked
  931  *      source file or directory is unlocked
  932  *      destination's parent directory is locked
  933  *      destination file or directory is locked if it exists
  934  *
  935  * On exit:
  936  *      all denodes should be released
  937  */
  938 static int
  939 msdosfs_rename(struct vop_rename_args *ap)
  940 {
  941         struct vnode *tdvp = ap->a_tdvp;
  942         struct vnode *fvp = ap->a_fvp;
  943         struct vnode *fdvp = ap->a_fdvp;
  944         struct vnode *tvp = ap->a_tvp;
  945         struct componentname *tcnp = ap->a_tcnp;
  946         struct componentname *fcnp = ap->a_fcnp;
  947         struct denode *ip, *xp, *dp, *zp;
  948         u_char toname[12], oldname[11];
  949         u_long from_diroffset, to_diroffset;
  950         u_char to_count;
  951         int doingdirectory = 0, newparent = 0;
  952         int error;
  953         u_long cn, pcl;
  954         daddr_t bn;
  955         struct msdosfsmount *pmp;
  956         struct direntry *dotdotp;
  957         struct buf *bp;
  958 
  959         pmp = VFSTOMSDOSFS(fdvp->v_mount);
  960 
  961 #ifdef DIAGNOSTIC
  962         if ((tcnp->cn_flags & HASBUF) == 0 ||
  963             (fcnp->cn_flags & HASBUF) == 0)
  964                 panic("msdosfs_rename: no name");
  965 #endif
  966         /*
  967          * Check for cross-device rename.
  968          */
  969         if (fvp->v_mount != tdvp->v_mount ||
  970             (tvp && fvp->v_mount != tvp->v_mount)) {
  971                 error = EXDEV;
  972 abortit:
  973                 if (tdvp == tvp)
  974                         vrele(tdvp);
  975                 else
  976                         vput(tdvp);
  977                 if (tvp)
  978                         vput(tvp);
  979                 vrele(fdvp);
  980                 vrele(fvp);
  981                 return (error);
  982         }
  983 
  984         /*
  985          * If source and dest are the same, do nothing.
  986          */
  987         if (tvp == fvp) {
  988                 error = 0;
  989                 goto abortit;
  990         }
  991 
  992         error = vn_lock(fvp, LK_EXCLUSIVE);
  993         if (error)
  994                 goto abortit;
  995         dp = VTODE(fdvp);
  996         ip = VTODE(fvp);
  997 
  998         /*
  999          * Be sure we are not renaming ".", "..", or an alias of ".". This
 1000          * leads to a crippled directory tree.  It's pretty tough to do a
 1001          * "ls" or "pwd" with the "." directory entry missing, and "cd .."
 1002          * doesn't work if the ".." entry is missing.
 1003          */
 1004         if (ip->de_Attributes & ATTR_DIRECTORY) {
 1005                 /*
 1006                  * Avoid ".", "..", and aliases of "." for obvious reasons.
 1007                  */
 1008                 if ((fcnp->cn_namelen == 1 && fcnp->cn_nameptr[0] == '.') ||
 1009                     dp == ip ||
 1010                     (fcnp->cn_flags & ISDOTDOT) ||
 1011                     (tcnp->cn_flags & ISDOTDOT) ||
 1012                     (ip->de_flag & DE_RENAME)) {
 1013                         VOP_UNLOCK(fvp, 0);
 1014                         error = EINVAL;
 1015                         goto abortit;
 1016                 }
 1017                 ip->de_flag |= DE_RENAME;
 1018                 doingdirectory++;
 1019         }
 1020 
 1021         /*
 1022          * When the target exists, both the directory
 1023          * and target vnodes are returned locked.
 1024          */
 1025         dp = VTODE(tdvp);
 1026         xp = tvp ? VTODE(tvp) : NULL;
 1027         /*
 1028          * Remember direntry place to use for destination
 1029          */
 1030         to_diroffset = dp->de_fndoffset;
 1031         to_count = dp->de_fndcnt;
 1032 
 1033         /*
 1034          * If ".." must be changed (ie the directory gets a new
 1035          * parent) then the source directory must not be in the
 1036          * directory hierarchy above the target, as this would
 1037          * orphan everything below the source directory. Also
 1038          * the user must have write permission in the source so
 1039          * as to be able to change "..". We must repeat the call
 1040          * to namei, as the parent directory is unlocked by the
 1041          * call to doscheckpath().
 1042          */
 1043         error = VOP_ACCESS(fvp, VWRITE, tcnp->cn_cred, tcnp->cn_thread);
 1044         VOP_UNLOCK(fvp, 0);
 1045         if (VTODE(fdvp)->de_StartCluster != VTODE(tdvp)->de_StartCluster)
 1046                 newparent = 1;
 1047         if (doingdirectory && newparent) {
 1048                 if (error)      /* write access check above */
 1049                         goto bad;
 1050                 if (xp != NULL)
 1051                         vput(tvp);
 1052                 /*
 1053                  * doscheckpath() vput()'s dp,
 1054                  * so we have to do a relookup afterwards
 1055                  */
 1056                 error = doscheckpath(ip, dp);
 1057                 if (error)
 1058                         goto out;
 1059                 if ((tcnp->cn_flags & SAVESTART) == 0)
 1060                         panic("msdosfs_rename: lost to startdir");
 1061                 error = relookup(tdvp, &tvp, tcnp);
 1062                 if (error)
 1063                         goto out;
 1064                 dp = VTODE(tdvp);
 1065                 xp = tvp ? VTODE(tvp) : NULL;
 1066         }
 1067 
 1068         if (xp != NULL) {
 1069                 /*
 1070                  * Target must be empty if a directory and have no links
 1071                  * to it. Also, ensure source and target are compatible
 1072                  * (both directories, or both not directories).
 1073                  */
 1074                 if (xp->de_Attributes & ATTR_DIRECTORY) {
 1075                         if (!dosdirempty(xp)) {
 1076                                 error = ENOTEMPTY;
 1077                                 goto bad;
 1078                         }
 1079                         if (!doingdirectory) {
 1080                                 error = ENOTDIR;
 1081                                 goto bad;
 1082                         }
 1083                         cache_purge(tdvp);
 1084                 } else if (doingdirectory) {
 1085                         error = EISDIR;
 1086                         goto bad;
 1087                 }
 1088                 error = removede(dp, xp);
 1089                 if (error)
 1090                         goto bad;
 1091                 vput(tvp);
 1092                 xp = NULL;
 1093         }
 1094 
 1095         /*
 1096          * Convert the filename in tcnp into a dos filename. We copy this
 1097          * into the denode and directory entry for the destination
 1098          * file/directory.
 1099          */
 1100         error = uniqdosname(VTODE(tdvp), tcnp, toname);
 1101         if (error)
 1102                 goto abortit;
 1103 
 1104         /*
 1105          * Since from wasn't locked at various places above,
 1106          * have to do a relookup here.
 1107          */
 1108         fcnp->cn_flags &= ~MODMASK;
 1109         fcnp->cn_flags |= LOCKPARENT | LOCKLEAF;
 1110         if ((fcnp->cn_flags & SAVESTART) == 0)
 1111                 panic("msdosfs_rename: lost from startdir");
 1112         if (!newparent)
 1113                 VOP_UNLOCK(tdvp, 0);
 1114         if (relookup(fdvp, &fvp, fcnp) == 0)
 1115                 vrele(fdvp);
 1116         if (fvp == NULL) {
 1117                 /*
 1118                  * From name has disappeared.
 1119                  */
 1120                 if (doingdirectory)
 1121                         panic("rename: lost dir entry");
 1122                 if (newparent)
 1123                         VOP_UNLOCK(tdvp, 0);
 1124                 vrele(tdvp);
 1125                 vrele(ap->a_fvp);
 1126                 return 0;
 1127         }
 1128         xp = VTODE(fvp);
 1129         zp = VTODE(fdvp);
 1130         from_diroffset = zp->de_fndoffset;
 1131 
 1132         /*
 1133          * Ensure that the directory entry still exists and has not
 1134          * changed till now. If the source is a file the entry may
 1135          * have been unlinked or renamed. In either case there is
 1136          * no further work to be done. If the source is a directory
 1137          * then it cannot have been rmdir'ed or renamed; this is
 1138          * prohibited by the DE_RENAME flag.
 1139          */
 1140         if (xp != ip) {
 1141                 if (doingdirectory)
 1142                         panic("rename: lost dir entry");
 1143                 VOP_UNLOCK(fvp, 0);
 1144                 if (newparent)
 1145                         VOP_UNLOCK(fdvp, 0);
 1146                 vrele(ap->a_fvp);
 1147                 xp = NULL;
 1148         } else {
 1149                 vrele(fvp);
 1150                 xp = NULL;
 1151 
 1152                 /*
 1153                  * First write a new entry in the destination
 1154                  * directory and mark the entry in the source directory
 1155                  * as deleted.  Then move the denode to the correct hash
 1156                  * chain for its new location in the filesystem.  And, if
 1157                  * we moved a directory, then update its .. entry to point
 1158                  * to the new parent directory.
 1159                  */
 1160                 memcpy(oldname, ip->de_Name, 11);
 1161                 memcpy(ip->de_Name, toname, 11);        /* update denode */
 1162                 dp->de_fndoffset = to_diroffset;
 1163                 dp->de_fndcnt = to_count;
 1164                 error = createde(ip, dp, (struct denode **)0, tcnp);
 1165                 if (error) {
 1166                         memcpy(ip->de_Name, oldname, 11);
 1167                         if (newparent)
 1168                                 VOP_UNLOCK(fdvp, 0);
 1169                         VOP_UNLOCK(fvp, 0);
 1170                         goto bad;
 1171                 }
 1172                 /*
 1173                  * If ip is for a directory, then its name should always
 1174                  * be "." since it is for the directory entry in the
 1175                  * directory itself (msdosfs_lookup() always translates
 1176                  * to the "." entry so as to get a unique denode, except
 1177                  * for the root directory there are different
 1178                  * complications).  However, we just corrupted its name
 1179                  * to pass the correct name to createde().  Undo this.
 1180                  */
 1181                 if ((ip->de_Attributes & ATTR_DIRECTORY) != 0)
 1182                         memcpy(ip->de_Name, oldname, 11);
 1183                 ip->de_refcnt++;
 1184                 zp->de_fndoffset = from_diroffset;
 1185                 error = removede(zp, ip);
 1186                 if (error) {
 1187                         /* XXX should downgrade to ro here, fs is corrupt */
 1188                         if (newparent)
 1189                                 VOP_UNLOCK(fdvp, 0);
 1190                         VOP_UNLOCK(fvp, 0);
 1191                         goto bad;
 1192                 }
 1193                 if (!doingdirectory) {
 1194                         error = pcbmap(dp, de_cluster(pmp, to_diroffset), 0,
 1195                                        &ip->de_dirclust, 0);
 1196                         if (error) {
 1197                                 /* XXX should downgrade to ro here, fs is corrupt */
 1198                                 if (newparent)
 1199                                         VOP_UNLOCK(fdvp, 0);
 1200                                 VOP_UNLOCK(fvp, 0);
 1201                                 goto bad;
 1202                         }
 1203                         if (ip->de_dirclust == MSDOSFSROOT)
 1204                                 ip->de_diroffset = to_diroffset;
 1205                         else
 1206                                 ip->de_diroffset = to_diroffset & pmp->pm_crbomask;
 1207                 }
 1208                 reinsert(ip);
 1209                 if (newparent)
 1210                         VOP_UNLOCK(fdvp, 0);
 1211         }
 1212 
 1213         /*
 1214          * If we moved a directory to a new parent directory, then we must
 1215          * fixup the ".." entry in the moved directory.
 1216          */
 1217         if (doingdirectory && newparent) {
 1218                 cn = ip->de_StartCluster;
 1219                 if (cn == MSDOSFSROOT) {
 1220                         /* this should never happen */
 1221                         panic("msdosfs_rename(): updating .. in root directory?");
 1222                 } else
 1223                         bn = cntobn(pmp, cn);
 1224                 error = bread(pmp->pm_devvp, bn, pmp->pm_bpcluster,
 1225                               NOCRED, &bp);
 1226                 if (error) {
 1227                         /* XXX should downgrade to ro here, fs is corrupt */
 1228                         brelse(bp);
 1229                         VOP_UNLOCK(fvp, 0);
 1230                         goto bad;
 1231                 }
 1232                 dotdotp = (struct direntry *)bp->b_data + 1;
 1233                 pcl = dp->de_StartCluster;
 1234                 if (FAT32(pmp) && pcl == pmp->pm_rootdirblk)
 1235                         pcl = MSDOSFSROOT;
 1236                 putushort(dotdotp->deStartCluster, pcl);
 1237                 if (FAT32(pmp))
 1238                         putushort(dotdotp->deHighClust, pcl >> 16);
 1239                 if (DOINGASYNC(fvp))
 1240                         bdwrite(bp);
 1241                 else if ((error = bwrite(bp)) != 0) {
 1242                         /* XXX should downgrade to ro here, fs is corrupt */
 1243                         VOP_UNLOCK(fvp, 0);
 1244                         goto bad;
 1245                 }
 1246         }
 1247 
 1248         /*
 1249          * The msdosfs lookup is case insensitive. Several aliases may
 1250          * be inserted for a single directory entry. As a consequnce,
 1251          * name cache purge done by lookup for fvp when DELETE op for
 1252          * namei is specified, might be not enough to expunge all
 1253          * namecache entries that were installed for this direntry.
 1254          */
 1255         cache_purge(fvp);
 1256         VOP_UNLOCK(fvp, 0);
 1257 bad:
 1258         if (xp)
 1259                 vput(tvp);
 1260         vput(tdvp);
 1261 out:
 1262         ip->de_flag &= ~DE_RENAME;
 1263         vrele(fdvp);
 1264         vrele(fvp);
 1265         return (error);
 1266 
 1267 }
 1268 
 1269 static struct {
 1270         struct direntry dot;
 1271         struct direntry dotdot;
 1272 } dosdirtemplate = {
 1273         {       ".          ",                          /* the . entry */
 1274                 ATTR_DIRECTORY,                         /* file attribute */
 1275                 0,                                      /* reserved */
 1276                 0, { 0, 0 }, { 0, 0 },                  /* create time & date */
 1277                 { 0, 0 },                               /* access date */
 1278                 { 0, 0 },                               /* high bits of start cluster */
 1279                 { 210, 4 }, { 210, 4 },                 /* modify time & date */
 1280                 { 0, 0 },                               /* startcluster */
 1281                 { 0, 0, 0, 0 }                          /* filesize */
 1282         },
 1283         {       "..         ",                          /* the .. entry */
 1284                 ATTR_DIRECTORY,                         /* file attribute */
 1285                 0,                                      /* reserved */
 1286                 0, { 0, 0 }, { 0, 0 },                  /* create time & date */
 1287                 { 0, 0 },                               /* access date */
 1288                 { 0, 0 },                               /* high bits of start cluster */
 1289                 { 210, 4 }, { 210, 4 },                 /* modify time & date */
 1290                 { 0, 0 },                               /* startcluster */
 1291                 { 0, 0, 0, 0 }                          /* filesize */
 1292         }
 1293 };
 1294 
 1295 static int
 1296 msdosfs_mkdir(struct vop_mkdir_args *ap)
 1297 {
 1298         struct componentname *cnp = ap->a_cnp;
 1299         struct denode *dep;
 1300         struct denode *pdep = VTODE(ap->a_dvp);
 1301         struct direntry *denp;
 1302         struct msdosfsmount *pmp = pdep->de_pmp;
 1303         struct buf *bp;
 1304         u_long newcluster, pcl;
 1305         int bn;
 1306         int error;
 1307         struct denode ndirent;
 1308         struct timespec ts;
 1309 
 1310         /*
 1311          * If this is the root directory and there is no space left we
 1312          * can't do anything.  This is because the root directory can not
 1313          * change size.
 1314          */
 1315         if (pdep->de_StartCluster == MSDOSFSROOT
 1316             && pdep->de_fndoffset >= pdep->de_FileSize) {
 1317                 error = ENOSPC;
 1318                 goto bad2;
 1319         }
 1320 
 1321         /*
 1322          * Allocate a cluster to hold the about to be created directory.
 1323          */
 1324         error = clusteralloc(pmp, 0, 1, CLUST_EOFE, &newcluster, NULL);
 1325         if (error)
 1326                 goto bad2;
 1327 
 1328         memset(&ndirent, 0, sizeof(ndirent));
 1329         ndirent.de_pmp = pmp;
 1330         ndirent.de_flag = DE_ACCESS | DE_CREATE | DE_UPDATE;
 1331         vfs_timestamp(&ts);
 1332         DETIMES(&ndirent, &ts, &ts, &ts);
 1333 
 1334         /*
 1335          * Now fill the cluster with the "." and ".." entries. And write
 1336          * the cluster to disk.  This way it is there for the parent
 1337          * directory to be pointing at if there were a crash.
 1338          */
 1339         bn = cntobn(pmp, newcluster);
 1340         /* always succeeds */
 1341         bp = getblk(pmp->pm_devvp, bn, pmp->pm_bpcluster, 0, 0, 0);
 1342         memset(bp->b_data, 0, pmp->pm_bpcluster);
 1343         memcpy(bp->b_data, &dosdirtemplate, sizeof dosdirtemplate);
 1344         denp = (struct direntry *)bp->b_data;
 1345         putushort(denp[0].deStartCluster, newcluster);
 1346         putushort(denp[0].deCDate, ndirent.de_CDate);
 1347         putushort(denp[0].deCTime, ndirent.de_CTime);
 1348         denp[0].deCHundredth = ndirent.de_CHun;
 1349         putushort(denp[0].deADate, ndirent.de_ADate);
 1350         putushort(denp[0].deMDate, ndirent.de_MDate);
 1351         putushort(denp[0].deMTime, ndirent.de_MTime);
 1352         pcl = pdep->de_StartCluster;
 1353         /*
 1354          * Although the root directory has a non-magic starting cluster
 1355          * number for FAT32, chkdsk and fsck_msdosfs still require
 1356          * references to it in dotdot entries to be magic.
 1357          */
 1358         if (FAT32(pmp) && pcl == pmp->pm_rootdirblk)
 1359                 pcl = MSDOSFSROOT;
 1360         putushort(denp[1].deStartCluster, pcl);
 1361         putushort(denp[1].deCDate, ndirent.de_CDate);
 1362         putushort(denp[1].deCTime, ndirent.de_CTime);
 1363         denp[1].deCHundredth = ndirent.de_CHun;
 1364         putushort(denp[1].deADate, ndirent.de_ADate);
 1365         putushort(denp[1].deMDate, ndirent.de_MDate);
 1366         putushort(denp[1].deMTime, ndirent.de_MTime);
 1367         if (FAT32(pmp)) {
 1368                 putushort(denp[0].deHighClust, newcluster >> 16);
 1369                 putushort(denp[1].deHighClust, pcl >> 16);
 1370         }
 1371 
 1372         if (DOINGASYNC(ap->a_dvp))
 1373                 bdwrite(bp);
 1374         else if ((error = bwrite(bp)) != 0)
 1375                 goto bad;
 1376 
 1377         /*
 1378          * Now build up a directory entry pointing to the newly allocated
 1379          * cluster.  This will be written to an empty slot in the parent
 1380          * directory.
 1381          */
 1382 #ifdef DIAGNOSTIC
 1383         if ((cnp->cn_flags & HASBUF) == 0)
 1384                 panic("msdosfs_mkdir: no name");
 1385 #endif
 1386         error = uniqdosname(pdep, cnp, ndirent.de_Name);
 1387         if (error)
 1388                 goto bad;
 1389 
 1390         ndirent.de_Attributes = ATTR_DIRECTORY;
 1391         ndirent.de_LowerCase = 0;
 1392         ndirent.de_StartCluster = newcluster;
 1393         ndirent.de_FileSize = 0;
 1394         error = createde(&ndirent, pdep, &dep, cnp);
 1395         if (error)
 1396                 goto bad;
 1397         *ap->a_vpp = DETOV(dep);
 1398         return (0);
 1399 
 1400 bad:
 1401         clusterfree(pmp, newcluster, NULL);
 1402 bad2:
 1403         return (error);
 1404 }
 1405 
 1406 static int
 1407 msdosfs_rmdir(struct vop_rmdir_args *ap)
 1408 {
 1409         struct vnode *vp = ap->a_vp;
 1410         struct vnode *dvp = ap->a_dvp;
 1411         struct componentname *cnp = ap->a_cnp;
 1412         struct denode *ip, *dp;
 1413         int error;
 1414 
 1415         ip = VTODE(vp);
 1416         dp = VTODE(dvp);
 1417 
 1418         /*
 1419          * Verify the directory is empty (and valid).
 1420          * (Rmdir ".." won't be valid since
 1421          *  ".." will contain a reference to
 1422          *  the current directory and thus be
 1423          *  non-empty.)
 1424          */
 1425         error = 0;
 1426         if (!dosdirempty(ip) || ip->de_flag & DE_RENAME) {
 1427                 error = ENOTEMPTY;
 1428                 goto out;
 1429         }
 1430         /*
 1431          * Delete the entry from the directory.  For dos filesystems this
 1432          * gets rid of the directory entry on disk, the in memory copy
 1433          * still exists but the de_refcnt is <= 0.  This prevents it from
 1434          * being found by deget().  When the vput() on dep is done we give
 1435          * up access and eventually msdosfs_reclaim() will be called which
 1436          * will remove it from the denode cache.
 1437          */
 1438         error = removede(dp, ip);
 1439         if (error)
 1440                 goto out;
 1441         /*
 1442          * This is where we decrement the link count in the parent
 1443          * directory.  Since dos filesystems don't do this we just purge
 1444          * the name cache.
 1445          */
 1446         cache_purge(dvp);
 1447         /*
 1448          * Truncate the directory that is being deleted.
 1449          */
 1450         error = detrunc(ip, (u_long)0, IO_SYNC, cnp->cn_cred);
 1451         cache_purge(vp);
 1452 
 1453 out:
 1454         return (error);
 1455 }
 1456 
 1457 /*
 1458  * DOS filesystems don't know what symlinks are.
 1459  */
 1460 static int
 1461 msdosfs_symlink(struct vop_symlink_args *ap)
 1462 {
 1463         return (EOPNOTSUPP);
 1464 }
 1465 
 1466 static int
 1467 msdosfs_readdir(struct vop_readdir_args *ap)
 1468 {
 1469         struct mbnambuf nb;
 1470         int error = 0;
 1471         int diff;
 1472         long n;
 1473         int blsize;
 1474         long on;
 1475         u_long cn;
 1476         u_long dirsperblk;
 1477         long bias = 0;
 1478         daddr_t bn, lbn;
 1479         struct buf *bp;
 1480         struct denode *dep = VTODE(ap->a_vp);
 1481         struct msdosfsmount *pmp = dep->de_pmp;
 1482         struct direntry *dentp;
 1483         struct dirent dirbuf;
 1484         struct uio *uio = ap->a_uio;
 1485         u_long *cookies = NULL;
 1486         int ncookies = 0;
 1487         off_t offset, off;
 1488         int chksum = -1;
 1489 
 1490 #ifdef MSDOSFS_DEBUG
 1491         printf("msdosfs_readdir(): vp %p, uio %p, cred %p, eofflagp %p\n",
 1492             ap->a_vp, uio, ap->a_cred, ap->a_eofflag);
 1493 #endif
 1494 
 1495         /*
 1496          * msdosfs_readdir() won't operate properly on regular files since
 1497          * it does i/o only with the filesystem vnode, and hence can
 1498          * retrieve the wrong block from the buffer cache for a plain file.
 1499          * So, fail attempts to readdir() on a plain file.
 1500          */
 1501         if ((dep->de_Attributes & ATTR_DIRECTORY) == 0)
 1502                 return (ENOTDIR);
 1503 
 1504         /*
 1505          * To be safe, initialize dirbuf
 1506          */
 1507         memset(dirbuf.d_name, 0, sizeof(dirbuf.d_name));
 1508 
 1509         /*
 1510          * If the user buffer is smaller than the size of one dos directory
 1511          * entry or the file offset is not a multiple of the size of a
 1512          * directory entry, then we fail the read.
 1513          */
 1514         off = offset = uio->uio_offset;
 1515         if (uio->uio_resid < sizeof(struct direntry) ||
 1516             (offset & (sizeof(struct direntry) - 1)))
 1517                 return (EINVAL);
 1518 
 1519         if (ap->a_ncookies) {
 1520                 ncookies = uio->uio_resid / 16;
 1521                 cookies = malloc(ncookies * sizeof(u_long), M_TEMP,
 1522                        M_WAITOK);
 1523                 *ap->a_cookies = cookies;
 1524                 *ap->a_ncookies = ncookies;
 1525         }
 1526 
 1527         dirsperblk = pmp->pm_BytesPerSec / sizeof(struct direntry);
 1528 
 1529         /*
 1530          * If they are reading from the root directory then, we simulate
 1531          * the . and .. entries since these don't exist in the root
 1532          * directory.  We also set the offset bias to make up for having to
 1533          * simulate these entries. By this I mean that at file offset 64 we
 1534          * read the first entry in the root directory that lives on disk.
 1535          */
 1536         if (dep->de_StartCluster == MSDOSFSROOT
 1537             || (FAT32(pmp) && dep->de_StartCluster == pmp->pm_rootdirblk)) {
 1538 #if 0
 1539                 printf("msdosfs_readdir(): going after . or .. in root dir, offset %d\n",
 1540                     offset);
 1541 #endif
 1542                 bias = 2 * sizeof(struct direntry);
 1543                 if (offset < bias) {
 1544                         for (n = (int)offset / sizeof(struct direntry);
 1545                              n < 2; n++) {
 1546                                 dirbuf.d_fileno = FAT32(pmp) ?
 1547                                     (uint64_t)cntobn(pmp, pmp->pm_rootdirblk) *
 1548                                     dirsperblk : 1;
 1549                                 dirbuf.d_type = DT_DIR;
 1550                                 switch (n) {
 1551                                 case 0:
 1552                                         dirbuf.d_namlen = 1;
 1553                                         dirbuf.d_name[0] = '.';
 1554                                         break;
 1555                                 case 1:
 1556                                         dirbuf.d_namlen = 2;
 1557                                         dirbuf.d_name[0] = '.';
 1558                                         dirbuf.d_name[1] = '.';
 1559                                         break;
 1560                                 }
 1561                                 dirbuf.d_reclen = GENERIC_DIRSIZ(&dirbuf);
 1562                                 /* NOTE: d_off is the offset of the *next* entry. */
 1563                                 dirbuf.d_off = offset + sizeof(struct direntry);
 1564                                 dirent_terminate(&dirbuf);
 1565                                 if (uio->uio_resid < dirbuf.d_reclen)
 1566                                         goto out;
 1567                                 error = uiomove(&dirbuf, dirbuf.d_reclen, uio);
 1568                                 if (error)
 1569                                         goto out;
 1570                                 offset += sizeof(struct direntry);
 1571                                 off = offset;
 1572                                 if (cookies) {
 1573                                         *cookies++ = offset;
 1574                                         if (--ncookies <= 0)
 1575                                                 goto out;
 1576                                 }
 1577                         }
 1578                 }
 1579         }
 1580 
 1581         mbnambuf_init(&nb);
 1582         off = offset;
 1583         while (uio->uio_resid > 0) {
 1584                 lbn = de_cluster(pmp, offset - bias);
 1585                 on = (offset - bias) & pmp->pm_crbomask;
 1586                 n = min(pmp->pm_bpcluster - on, uio->uio_resid);
 1587                 diff = dep->de_FileSize - (offset - bias);
 1588                 if (diff <= 0)
 1589                         break;
 1590                 n = min(n, diff);
 1591                 error = pcbmap(dep, lbn, &bn, &cn, &blsize);
 1592                 if (error)
 1593                         break;
 1594                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
 1595                 if (error) {
 1596                         brelse(bp);
 1597                         return (error);
 1598                 }
 1599                 n = min(n, blsize - bp->b_resid);
 1600                 if (n == 0) {
 1601                         brelse(bp);
 1602                         return (EIO);
 1603                 }
 1604 
 1605                 /*
 1606                  * Convert from dos directory entries to fs-independent
 1607                  * directory entries.
 1608                  */
 1609                 for (dentp = (struct direntry *)(bp->b_data + on);
 1610                      (char *)dentp < bp->b_data + on + n;
 1611                      dentp++, offset += sizeof(struct direntry)) {
 1612 #if 0
 1613                         printf("rd: dentp %08x prev %08x crnt %08x deName %02x attr %02x\n",
 1614                             dentp, prev, crnt, dentp->deName[0], dentp->deAttributes);
 1615 #endif
 1616                         /*
 1617                          * If this is an unused entry, we can stop.
 1618                          */
 1619                         if (dentp->deName[0] == SLOT_EMPTY) {
 1620                                 brelse(bp);
 1621                                 goto out;
 1622                         }
 1623                         /*
 1624                          * Skip deleted entries.
 1625                          */
 1626                         if (dentp->deName[0] == SLOT_DELETED) {
 1627                                 chksum = -1;
 1628                                 mbnambuf_init(&nb);
 1629                                 continue;
 1630                         }
 1631 
 1632                         /*
 1633                          * Handle Win95 long directory entries
 1634                          */
 1635                         if (dentp->deAttributes == ATTR_WIN95) {
 1636                                 if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
 1637                                         continue;
 1638                                 chksum = win2unixfn(&nb,
 1639                                     (struct winentry *)dentp, chksum, pmp);
 1640                                 continue;
 1641                         }
 1642 
 1643                         /*
 1644                          * Skip volume labels
 1645                          */
 1646                         if (dentp->deAttributes & ATTR_VOLUME) {
 1647                                 chksum = -1;
 1648                                 mbnambuf_init(&nb);
 1649                                 continue;
 1650                         }
 1651                         /*
 1652                          * This computation of d_fileno must match
 1653                          * the computation of va_fileid in
 1654                          * msdosfs_getattr.
 1655                          */
 1656                         if (dentp->deAttributes & ATTR_DIRECTORY) {
 1657                                 cn = getushort(dentp->deStartCluster);
 1658                                 if (FAT32(pmp)) {
 1659                                         cn |= getushort(dentp->deHighClust) <<
 1660                                             16;
 1661                                         if (cn == MSDOSFSROOT)
 1662                                                 cn = pmp->pm_rootdirblk;
 1663                                 }
 1664                                 if (cn == MSDOSFSROOT && !FAT32(pmp))
 1665                                         dirbuf.d_fileno = 1;
 1666                                 else
 1667                                         dirbuf.d_fileno = cntobn(pmp, cn) *
 1668                                             dirsperblk;
 1669                                 dirbuf.d_type = DT_DIR;
 1670                         } else {
 1671                                 dirbuf.d_fileno = (uoff_t)offset /
 1672                                     sizeof(struct direntry);
 1673                                 dirbuf.d_type = DT_REG;
 1674                         }
 1675 
 1676                         if (chksum != winChksum(dentp->deName)) {
 1677                                 dirbuf.d_namlen = dos2unixfn(dentp->deName,
 1678                                     (u_char *)dirbuf.d_name,
 1679                                     dentp->deLowerCase |
 1680                                         ((pmp->pm_flags & MSDOSFSMNT_SHORTNAME) ?
 1681                                         (LCASE_BASE | LCASE_EXT) : 0),
 1682                                     pmp);
 1683                                 mbnambuf_init(&nb);
 1684                         } else
 1685                                 mbnambuf_flush(&nb, &dirbuf);
 1686                         chksum = -1;
 1687                         dirbuf.d_reclen = GENERIC_DIRSIZ(&dirbuf);
 1688                         /* NOTE: d_off is the offset of the *next* entry. */
 1689                         dirbuf.d_off = offset + sizeof(struct direntry);
 1690                         dirent_terminate(&dirbuf);
 1691                         if (uio->uio_resid < dirbuf.d_reclen) {
 1692                                 brelse(bp);
 1693                                 goto out;
 1694                         }
 1695                         error = uiomove(&dirbuf, dirbuf.d_reclen, uio);
 1696                         if (error) {
 1697                                 brelse(bp);
 1698                                 goto out;
 1699                         }
 1700                         if (cookies) {
 1701                                 *cookies++ = offset + sizeof(struct direntry);
 1702                                 if (--ncookies <= 0) {
 1703                                         brelse(bp);
 1704                                         goto out;
 1705                                 }
 1706                         }
 1707                         off = offset + sizeof(struct direntry);
 1708                 }
 1709                 brelse(bp);
 1710         }
 1711 out:
 1712         /* Subtract unused cookies */
 1713         if (ap->a_ncookies)
 1714                 *ap->a_ncookies -= ncookies;
 1715 
 1716         uio->uio_offset = off;
 1717 
 1718         /*
 1719          * Set the eofflag (NFS uses it)
 1720          */
 1721         if (ap->a_eofflag) {
 1722                 if (dep->de_FileSize - (offset - bias) <= 0)
 1723                         *ap->a_eofflag = 1;
 1724                 else
 1725                         *ap->a_eofflag = 0;
 1726         }
 1727         return (error);
 1728 }
 1729 
 1730 /*-
 1731  * a_vp   - pointer to the file's vnode
 1732  * a_bn   - logical block number within the file (cluster number for us)
 1733  * a_bop  - where to return the bufobj of the special file containing the fs
 1734  * a_bnp  - where to return the "physical" block number corresponding to a_bn
 1735  *          (relative to the special file; units are blocks of size DEV_BSIZE)
 1736  * a_runp - where to return the "run past" a_bn.  This is the count of logical
 1737  *          blocks whose physical blocks (together with a_bn's physical block)
 1738  *          are contiguous.
 1739  * a_runb - where to return the "run before" a_bn.
 1740  */
 1741 static int
 1742 msdosfs_bmap(struct vop_bmap_args *ap)
 1743 {
 1744         struct denode *dep;
 1745         struct mount *mp;
 1746         struct msdosfsmount *pmp;
 1747         struct vnode *vp;
 1748         daddr_t runbn;
 1749         u_long cn;
 1750         int bnpercn, error, maxio, maxrun, run;
 1751 
 1752         vp = ap->a_vp;
 1753         dep = VTODE(vp);
 1754         pmp = dep->de_pmp;
 1755         if (ap->a_bop != NULL)
 1756                 *ap->a_bop = &pmp->pm_devvp->v_bufobj;
 1757         if (ap->a_bnp == NULL)
 1758                 return (0);
 1759         if (ap->a_runp != NULL)
 1760                 *ap->a_runp = 0;
 1761         if (ap->a_runb != NULL)
 1762                 *ap->a_runb = 0;
 1763         cn = ap->a_bn;
 1764         if (cn != ap->a_bn)
 1765                 return (EFBIG);
 1766         error = pcbmap(dep, cn, ap->a_bnp, NULL, NULL);
 1767         if (error != 0 || (ap->a_runp == NULL && ap->a_runb == NULL))
 1768                 return (error);
 1769 
 1770         mp = vp->v_mount;
 1771         maxio = mp->mnt_iosize_max / mp->mnt_stat.f_iosize;
 1772         bnpercn = de_cn2bn(pmp, 1);
 1773         if (ap->a_runp != NULL) {
 1774                 maxrun = ulmin(maxio - 1, pmp->pm_maxcluster - cn);
 1775                 for (run = 1; run <= maxrun; run++) {
 1776                         if (pcbmap(dep, cn + run, &runbn, NULL, NULL) != 0 ||
 1777                             runbn != *ap->a_bnp + run * bnpercn)
 1778                                 break;
 1779                 }
 1780                 *ap->a_runp = run - 1;
 1781         }
 1782         if (ap->a_runb != NULL) {
 1783                 maxrun = ulmin(maxio - 1, cn);
 1784                 for (run = 1; run < maxrun; run++) {
 1785                         if (pcbmap(dep, cn - run, &runbn, NULL, NULL) != 0 ||
 1786                             runbn != *ap->a_bnp - run * bnpercn)
 1787                                 break;
 1788                 }
 1789                 *ap->a_runb = run - 1;
 1790         }
 1791         return (0);
 1792 }
 1793 
 1794 SYSCTL_NODE(_vfs, OID_AUTO, msdosfs, CTLFLAG_RW, 0, "msdos filesystem");
 1795 static int use_buf_pager = 1;
 1796 SYSCTL_INT(_vfs_msdosfs, OID_AUTO, use_buf_pager, CTLFLAG_RWTUN,
 1797     &use_buf_pager, 0,
 1798     "Use buffer pager instead of bmap");
 1799 
 1800 static daddr_t
 1801 msdosfs_gbp_getblkno(struct vnode *vp, vm_ooffset_t off)
 1802 {
 1803 
 1804         return (de_cluster(VTODE(vp)->de_pmp, off));
 1805 }
 1806 
 1807 static int
 1808 msdosfs_gbp_getblksz(struct vnode *vp, daddr_t lbn, long *sz)
 1809 {
 1810 
 1811         *sz = VTODE(vp)->de_pmp->pm_bpcluster;
 1812         return (0);
 1813 }
 1814 
 1815 static int
 1816 msdosfs_getpages(struct vop_getpages_args *ap)
 1817 {
 1818 
 1819         if (use_buf_pager)
 1820                 return (vfs_bio_getpages(ap->a_vp, ap->a_m, ap->a_count,
 1821                     ap->a_rbehind, ap->a_rahead, msdosfs_gbp_getblkno,
 1822                     msdosfs_gbp_getblksz));
 1823         return (vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
 1824             ap->a_rbehind, ap->a_rahead, NULL, NULL));
 1825 }
 1826 
 1827 static int
 1828 msdosfs_strategy(struct vop_strategy_args *ap)
 1829 {
 1830         struct buf *bp = ap->a_bp;
 1831         struct denode *dep = VTODE(ap->a_vp);
 1832         struct bufobj *bo;
 1833         int error = 0;
 1834         daddr_t blkno;
 1835 
 1836         /*
 1837          * If we don't already know the filesystem relative block number
 1838          * then get it using pcbmap().  If pcbmap() returns the block
 1839          * number as -1 then we've got a hole in the file.  DOS filesystems
 1840          * don't allow files with holes, so we shouldn't ever see this.
 1841          */
 1842         if (bp->b_blkno == bp->b_lblkno) {
 1843                 error = pcbmap(dep, bp->b_lblkno, &blkno, 0, 0);
 1844                 bp->b_blkno = blkno;
 1845                 if (error) {
 1846                         bp->b_error = error;
 1847                         bp->b_ioflags |= BIO_ERROR;
 1848                         bufdone(bp);
 1849                         return (0);
 1850                 }
 1851                 if ((long)bp->b_blkno == -1)
 1852                         vfs_bio_clrbuf(bp);
 1853         }
 1854         if (bp->b_blkno == -1) {
 1855                 bufdone(bp);
 1856                 return (0);
 1857         }
 1858         /*
 1859          * Read/write the block from/to the disk that contains the desired
 1860          * file block.
 1861          */
 1862         bp->b_iooffset = dbtob(bp->b_blkno);
 1863         bo = dep->de_pmp->pm_bo;
 1864         BO_STRATEGY(bo, bp);
 1865         return (0);
 1866 }
 1867 
 1868 static int
 1869 msdosfs_print(struct vop_print_args *ap)
 1870 {
 1871         struct denode *dep = VTODE(ap->a_vp);
 1872 
 1873         printf("\tstartcluster %lu, dircluster %lu, diroffset %lu, ",
 1874                dep->de_StartCluster, dep->de_dirclust, dep->de_diroffset);
 1875         printf("on dev %s\n", devtoname(dep->de_pmp->pm_dev));
 1876         return (0);
 1877 }
 1878 
 1879 static int
 1880 msdosfs_pathconf(struct vop_pathconf_args *ap)
 1881 {
 1882         struct msdosfsmount *pmp = VTODE(ap->a_vp)->de_pmp;
 1883 
 1884         switch (ap->a_name) {
 1885         case _PC_FILESIZEBITS:
 1886                 *ap->a_retval = 32;
 1887                 return (0);
 1888         case _PC_LINK_MAX:
 1889                 *ap->a_retval = 1;
 1890                 return (0);
 1891         case _PC_NAME_MAX:
 1892                 *ap->a_retval = pmp->pm_flags & MSDOSFSMNT_LONGNAME ? WIN_MAXLEN : 12;
 1893                 return (0);
 1894         case _PC_CHOWN_RESTRICTED:
 1895                 *ap->a_retval = 1;
 1896                 return (0);
 1897         case _PC_NO_TRUNC:
 1898                 *ap->a_retval = 0;
 1899                 return (0);
 1900         default:
 1901                 return (vop_stdpathconf(ap));
 1902         }
 1903         /* NOTREACHED */
 1904 }
 1905 
 1906 static int
 1907 msdosfs_vptofh(struct vop_vptofh_args *ap)
 1908 {
 1909         struct denode *dep;
 1910         struct defid *defhp;
 1911 
 1912         dep = VTODE(ap->a_vp);
 1913         defhp = (struct defid *)ap->a_fhp;
 1914         defhp->defid_len = sizeof(struct defid);
 1915         defhp->defid_dirclust = dep->de_dirclust;
 1916         defhp->defid_dirofs = dep->de_diroffset;
 1917         /* defhp->defid_gen = dep->de_gen; */
 1918         return (0);
 1919 }
 1920 
 1921 /* Global vfs data structures for msdosfs */
 1922 struct vop_vector msdosfs_vnodeops = {
 1923         .vop_default =          &default_vnodeops,
 1924 
 1925         .vop_access =           msdosfs_access,
 1926         .vop_bmap =             msdosfs_bmap,
 1927         .vop_getpages =         msdosfs_getpages,
 1928         .vop_cachedlookup =     msdosfs_lookup,
 1929         .vop_open =             msdosfs_open,
 1930         .vop_close =            msdosfs_close,
 1931         .vop_create =           msdosfs_create,
 1932         .vop_fsync =            msdosfs_fsync,
 1933         .vop_fdatasync =        vop_stdfdatasync_buf,
 1934         .vop_getattr =          msdosfs_getattr,
 1935         .vop_inactive =         msdosfs_inactive,
 1936         .vop_link =             msdosfs_link,
 1937         .vop_lookup =           vfs_cache_lookup,
 1938         .vop_mkdir =            msdosfs_mkdir,
 1939         .vop_mknod =            msdosfs_mknod,
 1940         .vop_pathconf =         msdosfs_pathconf,
 1941         .vop_print =            msdosfs_print,
 1942         .vop_read =             msdosfs_read,
 1943         .vop_readdir =          msdosfs_readdir,
 1944         .vop_reclaim =          msdosfs_reclaim,
 1945         .vop_remove =           msdosfs_remove,
 1946         .vop_rename =           msdosfs_rename,
 1947         .vop_rmdir =            msdosfs_rmdir,
 1948         .vop_setattr =          msdosfs_setattr,
 1949         .vop_strategy =         msdosfs_strategy,
 1950         .vop_symlink =          msdosfs_symlink,
 1951         .vop_write =            msdosfs_write,
 1952         .vop_vptofh =           msdosfs_vptofh,
 1953 };

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