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: releng/10.1/sys/fs/fdescfs/fdesc_vfsops.c 247602 2013-03-02 00:53:12Z pjd $
   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/racct.h>
   51 #include <sys/resourcevar.h>
   52 #include <sys/vnode.h>
   53 
   54 #include <fs/fdescfs/fdesc.h>
   55 
   56 static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure");
   57 
   58 static vfs_cmount_t     fdesc_cmount;
   59 static vfs_mount_t      fdesc_mount;
   60 static vfs_unmount_t    fdesc_unmount;
   61 static vfs_statfs_t     fdesc_statfs;
   62 static vfs_root_t       fdesc_root;
   63 
   64 /*
   65  * Compatibility shim for old mount(2) system call.
   66  */
   67 int
   68 fdesc_cmount(struct mntarg *ma, void *data, uint64_t flags)
   69 {
   70         return kernel_mount(ma, flags);
   71 }
   72 
   73 /*
   74  * Mount the per-process file descriptors (/dev/fd)
   75  */
   76 static int
   77 fdesc_mount(struct mount *mp)
   78 {
   79         int error = 0;
   80         struct fdescmount *fmp;
   81         struct vnode *rvp;
   82 
   83         /*
   84          * Update is a no-op
   85          */
   86         if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS))
   87                 return (EOPNOTSUPP);
   88 
   89         fmp = malloc(sizeof(struct fdescmount),
   90                                 M_FDESCMNT, M_WAITOK);  /* XXX */
   91 
   92         /*
   93          * We need to initialize a few bits of our local mount point struct to
   94          * avoid confusion in allocvp.
   95          */
   96         mp->mnt_data = (qaddr_t) fmp;
   97         fmp->flags = 0;
   98         error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp);
   99         if (error) {
  100                 free(fmp, M_FDESCMNT);
  101                 mp->mnt_data = NULL;
  102                 return (error);
  103         }
  104         rvp->v_type = VDIR;
  105         rvp->v_vflag |= VV_ROOT;
  106         fmp->f_root = rvp;
  107         VOP_UNLOCK(rvp, 0);
  108         /* XXX -- don't mark as local to work around fts() problems */
  109         /*mp->mnt_flag |= MNT_LOCAL;*/
  110         vfs_getnewfsid(mp);
  111 
  112         vfs_mountedfrom(mp, "fdescfs");
  113         return (0);
  114 }
  115 
  116 static int
  117 fdesc_unmount(mp, mntflags)
  118         struct mount *mp;
  119         int mntflags;
  120 {
  121         struct fdescmount *fmp;
  122         caddr_t data;
  123         int error;
  124         int flags = 0;
  125 
  126         fmp = (struct fdescmount *)mp->mnt_data;
  127         if (mntflags & MNT_FORCE) {
  128                 /* The hash mutex protects the private mount flags. */
  129                 mtx_lock(&fdesc_hashmtx);
  130                 fmp->flags |= FMNT_UNMOUNTF;
  131                 mtx_unlock(&fdesc_hashmtx);
  132                 flags |= FORCECLOSE;
  133         }
  134 
  135         /*
  136          * Clear out buffer cache.  I don't think we
  137          * ever get anything cached at this level at the
  138          * moment, but who knows...
  139          *
  140          * There is 1 extra root vnode reference corresponding
  141          * to f_root.
  142          */
  143         if ((error = vflush(mp, 1, flags, curthread)) != 0)
  144                 return (error);
  145 
  146         /*
  147          * Finally, throw away the fdescmount structure. Hold the hashmtx to
  148          * protect the fdescmount structure.
  149          */
  150         mtx_lock(&fdesc_hashmtx);
  151         data = mp->mnt_data;
  152         mp->mnt_data = NULL;
  153         mtx_unlock(&fdesc_hashmtx);
  154         free(data, M_FDESCMNT); /* XXX */
  155 
  156         return (0);
  157 }
  158 
  159 static int
  160 fdesc_root(mp, flags, vpp)
  161         struct mount *mp;
  162         int flags;
  163         struct vnode **vpp;
  164 {
  165         struct vnode *vp;
  166 
  167         /*
  168          * Return locked reference to root.
  169          */
  170         vp = VFSTOFDESC(mp)->f_root;
  171         vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread);
  172         *vpp = vp;
  173         return (0);
  174 }
  175 
  176 static int
  177 fdesc_statfs(mp, sbp)
  178         struct mount *mp;
  179         struct statfs *sbp;
  180 {
  181         struct thread *td;
  182         struct filedesc *fdp;
  183         int lim;
  184         int i;
  185         int last;
  186         int freefd;
  187         uint64_t limit;
  188 
  189         td = curthread;
  190 
  191         /*
  192          * Compute number of free file descriptors.
  193          * [ Strange results will ensue if the open file
  194          * limit is ever reduced below the current number
  195          * of open files... ]
  196          */
  197         PROC_LOCK(td->td_proc);
  198         lim = lim_cur(td->td_proc, RLIMIT_NOFILE);
  199         PROC_UNLOCK(td->td_proc);
  200         fdp = td->td_proc->p_fd;
  201         FILEDESC_SLOCK(fdp);
  202         limit = racct_get_limit(td->td_proc, RACCT_NOFILE);
  203         if (lim > limit)
  204                 lim = limit;
  205         last = min(fdp->fd_nfiles, lim);
  206         freefd = 0;
  207         for (i = fdp->fd_freefile; i < last; i++)
  208                 if (fdp->fd_ofiles[i].fde_file == NULL)
  209                         freefd++;
  210 
  211         /*
  212          * Adjust for the fact that the fdesc array may not
  213          * have been fully allocated yet.
  214          */
  215         if (fdp->fd_nfiles < lim)
  216                 freefd += (lim - fdp->fd_nfiles);
  217         FILEDESC_SUNLOCK(fdp);
  218 
  219         sbp->f_flags = 0;
  220         sbp->f_bsize = DEV_BSIZE;
  221         sbp->f_iosize = DEV_BSIZE;
  222         sbp->f_blocks = 2;              /* 1K to keep df happy */
  223         sbp->f_bfree = 0;
  224         sbp->f_bavail = 0;
  225         sbp->f_files = lim + 1;         /* Allow for "." */
  226         sbp->f_ffree = freefd;          /* See comments above */
  227         return (0);
  228 }
  229 
  230 static struct vfsops fdesc_vfsops = {
  231         .vfs_cmount =           fdesc_cmount,
  232         .vfs_init =             fdesc_init,
  233         .vfs_mount =            fdesc_mount,
  234         .vfs_root =             fdesc_root,
  235         .vfs_statfs =           fdesc_statfs,
  236         .vfs_uninit =           fdesc_uninit,
  237         .vfs_unmount =          fdesc_unmount,
  238 };
  239 
  240 VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC);

Cache object: 3329d21a65ed2aa48d64f2de846bc063

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FreeBSD/Linux Kernel Cross Reference sys/fs/fdescfs/fdesc_vfsops.c

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sys/fs/fdescfs/fdesc_vfsops.c