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

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sys/fs/fdescfs/fdesc_vfsops.c