fdesc_vfsops.c

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    1 /*
    2  * Copyright (c) 1992, 1993, 1995
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software donated to Berkeley by
    6  * Jan-Simon Pendry.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. All advertising materials mentioning features or use of this software
   17  *    must display the following acknowledgement:
   18  *      This product includes software developed by the University of
   19  *      California, Berkeley and its contributors.
   20  * 4. Neither the name of the University nor the names of its contributors
   21  *    may be used to endorse or promote products derived from this software
   22  *    without specific prior written permission.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   34  * SUCH DAMAGE.
   35  *
   36  *      @(#)fdesc_vfsops.c      8.4 (Berkeley) 1/21/94
   37  *
   38  * $FreeBSD: releng/5.0/sys/fs/fdescfs/fdesc_vfsops.c 101308 2002-08-04 10:29:36Z jeff $
   39  */
   40 
   41 /*
   42  * /dev/fd Filesystem
   43  */
   44 
   45 #include <sys/param.h>
   46 #include <sys/systm.h>
   47 #include <sys/filedesc.h>
   48 #include <sys/kernel.h>
   49 #include <sys/lock.h>
   50 #include <sys/mutex.h>
   51 #include <sys/malloc.h>
   52 #include <sys/mount.h>
   53 #include <sys/proc.h>
   54 #include <sys/resourcevar.h>
   55 #include <sys/vnode.h>
   56 
   57 #include <fs/fdescfs/fdesc.h>
   58 
   59 static MALLOC_DEFINE(M_FDESCMNT, "FDESC mount", "FDESC mount structure");
   60 
   61 static int      fdesc_mount(struct mount *mp, struct nameidata *ndp,
   62                                  struct thread *td);
   63 static int      fdesc_unmount(struct mount *mp, int mntflags,
   64                                    struct thread *td);
   65 static int      fdesc_statfs(struct mount *mp, struct statfs *sbp,
   66                                   struct thread *td);
   67   
   68 /*
   69  * Mount the per-process file descriptors (/dev/fd)
   70  */
   71 static int
   72 fdesc_mount(mp, ndp, td)
   73         struct mount *mp;
   74         struct nameidata *ndp;
   75         struct thread *td;
   76 {
   77         int error = 0;
   78         struct fdescmount *fmp;
   79         struct vnode *rvp;
   80 
   81         /*
   82          * Update is a no-op
   83          */
   84         if (mp->mnt_flag & MNT_UPDATE)
   85                 return (EOPNOTSUPP);
   86 
   87         error = fdesc_allocvp(Froot, FD_ROOT, mp, &rvp, td);
   88         if (error)
   89                 return (error);
   90 
   91         MALLOC(fmp, struct fdescmount *, sizeof(struct fdescmount),
   92                                 M_FDESCMNT, M_WAITOK);  /* XXX */
   93         rvp->v_type = VDIR;
   94         rvp->v_vflag |= VV_ROOT;
   95         fmp->f_root = rvp;
   96         /* XXX -- don't mark as local to work around fts() problems */
   97         /*mp->mnt_flag |= MNT_LOCAL;*/
   98         mp->mnt_data = (qaddr_t) fmp;
   99         vfs_getnewfsid(mp);
  100 
  101         bzero(mp->mnt_stat.f_mntfromname, MNAMELEN);
  102         bcopy("fdesc", mp->mnt_stat.f_mntfromname, sizeof("fdesc"));
  103         (void)fdesc_statfs(mp, &mp->mnt_stat, td);
  104         return (0);
  105 }
  106 
  107 static int
  108 fdesc_unmount(mp, mntflags, td)
  109         struct mount *mp;
  110         int mntflags;
  111         struct thread *td;
  112 {
  113         int error;
  114         int flags = 0;
  115 
  116         if (mntflags & MNT_FORCE)
  117                 flags |= FORCECLOSE;
  118 
  119         /*
  120          * Clear out buffer cache.  I don't think we
  121          * ever get anything cached at this level at the
  122          * moment, but who knows...
  123          *
  124          * There is 1 extra root vnode reference corresponding
  125          * to f_root.
  126          */
  127         if ((error = vflush(mp, 1, flags)) != 0)
  128                 return (error);
  129 
  130         /*
  131          * Finally, throw away the fdescmount structure
  132          */
  133         free(mp->mnt_data, M_FDESCMNT); /* XXX */
  134         mp->mnt_data = 0;
  135 
  136         return (0);
  137 }
  138 
  139 int
  140 fdesc_root(mp, vpp)
  141         struct mount *mp;
  142         struct vnode **vpp;
  143 {
  144         struct thread *td = curthread;  /* XXX */
  145         struct vnode *vp;
  146 
  147         /*
  148          * Return locked reference to root.
  149          */
  150         vp = VFSTOFDESC(mp)->f_root;
  151         VREF(vp);
  152         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
  153         *vpp = vp;
  154         return (0);
  155 }
  156 
  157 static int
  158 fdesc_statfs(mp, sbp, td)
  159         struct mount *mp;
  160         struct statfs *sbp;
  161         struct thread *td;
  162 {
  163         struct filedesc *fdp;
  164         int lim;
  165         int i;
  166         int last;
  167         int freefd;
  168 
  169         /*
  170          * Compute number of free file descriptors.
  171          * [ Strange results will ensue if the open file
  172          * limit is ever reduced below the current number
  173          * of open files... ]
  174          */
  175         lim = td->td_proc->p_rlimit[RLIMIT_NOFILE].rlim_cur;
  176         fdp = td->td_proc->p_fd;
  177         FILEDESC_LOCK(fdp);
  178         last = min(fdp->fd_nfiles, lim);
  179         freefd = 0;
  180         for (i = fdp->fd_freefile; i < last; i++)
  181                 if (fdp->fd_ofiles[i] == NULL)
  182                         freefd++;
  183 
  184         /*
  185          * Adjust for the fact that the fdesc array may not
  186          * have been fully allocated yet.
  187          */
  188         if (fdp->fd_nfiles < lim)
  189                 freefd += (lim - fdp->fd_nfiles);
  190         FILEDESC_UNLOCK(fdp);
  191 
  192         sbp->f_flags = 0;
  193         sbp->f_bsize = DEV_BSIZE;
  194         sbp->f_iosize = DEV_BSIZE;
  195         sbp->f_blocks = 2;              /* 1K to keep df happy */
  196         sbp->f_bfree = 0;
  197         sbp->f_bavail = 0;
  198         sbp->f_files = lim + 1;         /* Allow for "." */
  199         sbp->f_ffree = freefd;          /* See comments above */
  200         if (sbp != &mp->mnt_stat) {
  201                 sbp->f_type = mp->mnt_vfc->vfc_typenum;
  202                 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
  203                 bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
  204                 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
  205         }
  206         return (0);
  207 }
  208 
  209 static struct vfsops fdesc_vfsops = {
  210         NULL,
  211         vfs_stdstart,
  212         fdesc_unmount,
  213         fdesc_root,
  214         vfs_stdquotactl,
  215         fdesc_statfs,
  216         vfs_stdsync,
  217         vfs_stdvget,
  218         vfs_stdfhtovp,
  219         vfs_stdcheckexp,
  220         vfs_stdvptofh,
  221         fdesc_init,
  222         vfs_stduninit,
  223         vfs_stdextattrctl,
  224         fdesc_mount,
  225 };
  226 
  227 VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC);

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sys/fs/fdescfs/fdesc_vfsops.c