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. 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/11.0/sys/fs/fdescfs/fdesc_vfsops.c 298853 2016-04-30 16:01:37Z emaste $
   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/jail.h>
   46 #include <sys/lock.h>
   47 #include <sys/mutex.h>
   48 #include <sys/malloc.h>
   49 #include <sys/mount.h>
   50 #include <sys/proc.h>
   51 #include <sys/racct.h>
   52 #include <sys/resourcevar.h>
   53 #include <sys/vnode.h>
   54 
   55 #include <fs/fdescfs/fdesc.h>
   56 
   57 static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure");
   58 
   59 static vfs_cmount_t     fdesc_cmount;
   60 static vfs_mount_t      fdesc_mount;
   61 static vfs_unmount_t    fdesc_unmount;
   62 static vfs_statfs_t     fdesc_statfs;
   63 static vfs_root_t       fdesc_root;
   64 
   65 /*
   66  * Compatibility shim for old mount(2) system call.
   67  */
   68 int
   69 fdesc_cmount(struct mntarg *ma, void *data, uint64_t flags)
   70 {
   71         return kernel_mount(ma, flags);
   72 }
   73 
   74 /*
   75  * Mount the per-process file descriptors (/dev/fd)
   76  */
   77 static int
   78 fdesc_mount(struct mount *mp)
   79 {
   80         int error = 0;
   81         struct fdescmount *fmp;
   82         struct thread *td = curthread;
   83         struct vnode *rvp;
   84 
   85         if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_FDESCFS))
   86                 return (EPERM);
   87 
   88         /*
   89          * Update is a no-op
   90          */
   91         if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS))
   92                 return (EOPNOTSUPP);
   93 
   94         fmp = malloc(sizeof(struct fdescmount),
   95                                 M_FDESCMNT, M_WAITOK);  /* XXX */
   96 
   97         /*
   98          * We need to initialize a few bits of our local mount point struct to
   99          * avoid confusion in allocvp.
  100          */
  101         mp->mnt_data = (qaddr_t) fmp;
  102         fmp->flags = 0;
  103         error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp);
  104         if (error) {
  105                 free(fmp, M_FDESCMNT);
  106                 mp->mnt_data = NULL;
  107                 return (error);
  108         }
  109         rvp->v_type = VDIR;
  110         rvp->v_vflag |= VV_ROOT;
  111         fmp->f_root = rvp;
  112         VOP_UNLOCK(rvp, 0);
  113         /* XXX -- don't mark as local to work around fts() problems */
  114         /*mp->mnt_flag |= MNT_LOCAL;*/
  115         vfs_getnewfsid(mp);
  116 
  117         vfs_mountedfrom(mp, "fdescfs");
  118         return (0);
  119 }
  120 
  121 static int
  122 fdesc_unmount(struct mount *mp, int mntflags)
  123 {
  124         struct fdescmount *fmp;
  125         caddr_t data;
  126         int error;
  127         int flags = 0;
  128 
  129         fmp = (struct fdescmount *)mp->mnt_data;
  130         if (mntflags & MNT_FORCE) {
  131                 /* The hash mutex protects the private mount flags. */
  132                 mtx_lock(&fdesc_hashmtx);
  133                 fmp->flags |= FMNT_UNMOUNTF;
  134                 mtx_unlock(&fdesc_hashmtx);
  135                 flags |= FORCECLOSE;
  136         }
  137 
  138         /*
  139          * Clear out buffer cache.  I don't think we
  140          * ever get anything cached at this level at the
  141          * moment, but who knows...
  142          *
  143          * There is 1 extra root vnode reference corresponding
  144          * to f_root.
  145          */
  146         if ((error = vflush(mp, 1, flags, curthread)) != 0)
  147                 return (error);
  148 
  149         /*
  150          * Finally, throw away the fdescmount structure. Hold the hashmtx to
  151          * protect the fdescmount structure.
  152          */
  153         mtx_lock(&fdesc_hashmtx);
  154         data = mp->mnt_data;
  155         mp->mnt_data = NULL;
  156         mtx_unlock(&fdesc_hashmtx);
  157         free(data, M_FDESCMNT); /* XXX */
  158 
  159         return (0);
  160 }
  161 
  162 static int
  163 fdesc_root(struct mount *mp, int flags, 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(struct mount *mp, struct statfs *sbp)
  178 {
  179         struct thread *td;
  180         struct filedesc *fdp;
  181         int lim;
  182         int i;
  183         int last;
  184         int freefd;
  185         uint64_t limit;
  186 
  187         td = curthread;
  188 
  189         /*
  190          * Compute number of free file descriptors.
  191          * [ Strange results will ensue if the open file
  192          * limit is ever reduced below the current number
  193          * of open files... ]
  194          */
  195         lim = lim_cur(td, RLIMIT_NOFILE);
  196         fdp = td->td_proc->p_fd;
  197         FILEDESC_SLOCK(fdp);
  198         limit = racct_get_limit(td->td_proc, RACCT_NOFILE);
  199         if (lim > limit)
  200                 lim = limit;
  201         last = min(fdp->fd_nfiles, lim);
  202         freefd = 0;
  203         for (i = fdp->fd_freefile; i < last; i++)
  204                 if (fdp->fd_ofiles[i].fde_file == NULL)
  205                         freefd++;
  206 
  207         /*
  208          * Adjust for the fact that the fdesc array may not
  209          * have been fully allocated yet.
  210          */
  211         if (fdp->fd_nfiles < lim)
  212                 freefd += (lim - fdp->fd_nfiles);
  213         FILEDESC_SUNLOCK(fdp);
  214 
  215         sbp->f_flags = 0;
  216         sbp->f_bsize = DEV_BSIZE;
  217         sbp->f_iosize = DEV_BSIZE;
  218         sbp->f_blocks = 2;              /* 1K to keep df happy */
  219         sbp->f_bfree = 0;
  220         sbp->f_bavail = 0;
  221         sbp->f_files = lim + 1;         /* Allow for "." */
  222         sbp->f_ffree = freefd;          /* See comments above */
  223         return (0);
  224 }
  225 
  226 static struct vfsops fdesc_vfsops = {
  227         .vfs_cmount =           fdesc_cmount,
  228         .vfs_init =             fdesc_init,
  229         .vfs_mount =            fdesc_mount,
  230         .vfs_root =             fdesc_root,
  231         .vfs_statfs =           fdesc_statfs,
  232         .vfs_uninit =           fdesc_uninit,
  233         .vfs_unmount =          fdesc_unmount,
  234 };
  235 
  236 VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL);

Cache object: e32a2fe014d91ded5e8b109e808bd2cd

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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