243 lines
6.1 KiB
C
243 lines
6.1 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1992, 1993, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software donated to Berkeley by
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* Jan-Simon Pendry.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)fdesc_vfsops.c 8.4 (Berkeley) 1/21/94
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*
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* $FreeBSD$
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*/
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/*
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* /dev/fd Filesystem
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/filedesc.h>
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#include <sys/kernel.h>
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#include <sys/jail.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/malloc.h>
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#include <sys/mount.h>
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#include <sys/proc.h>
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#include <sys/racct.h>
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#include <sys/resourcevar.h>
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#include <sys/vnode.h>
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#include <fs/fdescfs/fdesc.h>
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static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure");
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static vfs_cmount_t fdesc_cmount;
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static vfs_mount_t fdesc_mount;
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static vfs_unmount_t fdesc_unmount;
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static vfs_statfs_t fdesc_statfs;
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static vfs_root_t fdesc_root;
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/*
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* Compatibility shim for old mount(2) system call.
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*/
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int
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fdesc_cmount(struct mntarg *ma, void *data, uint64_t flags)
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{
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return kernel_mount(ma, flags);
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}
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/*
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* Mount the per-process file descriptors (/dev/fd)
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*/
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static int
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fdesc_mount(struct mount *mp)
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{
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struct fdescmount *fmp;
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struct vnode *rvp;
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int error;
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/*
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* Update is a no-op
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*/
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if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS))
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return (EOPNOTSUPP);
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fmp = malloc(sizeof(struct fdescmount),
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M_FDESCMNT, M_WAITOK); /* XXX */
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/*
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* We need to initialize a few bits of our local mount point struct to
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* avoid confusion in allocvp.
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*/
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mp->mnt_data = fmp;
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fmp->flags = 0;
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if (vfs_getopt(mp->mnt_optnew, "linrdlnk", NULL, NULL) == 0)
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fmp->flags |= FMNT_LINRDLNKF;
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error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp);
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if (error) {
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free(fmp, M_FDESCMNT);
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mp->mnt_data = NULL;
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return (error);
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}
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VN_LOCK_ASHARE(rvp);
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rvp->v_type = VDIR;
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rvp->v_vflag |= VV_ROOT;
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fmp->f_root = rvp;
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VOP_UNLOCK(rvp);
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MNT_ILOCK(mp);
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/* XXX -- don't mark as local to work around fts() problems */
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/*mp->mnt_flag |= MNT_LOCAL;*/
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/*
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* Enable shared locking so that there is no contention on the root
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* vnode. Note only root vnode enables shared locking for itself,
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* so this end up being a nop for the rest.
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*/
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mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED;
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MNT_IUNLOCK(mp);
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vfs_getnewfsid(mp);
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vfs_mountedfrom(mp, "fdescfs");
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return (0);
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}
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static int
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fdesc_unmount(struct mount *mp, int mntflags)
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{
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struct fdescmount *fmp;
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int error, flags;
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flags = 0;
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fmp = mp->mnt_data;
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if (mntflags & MNT_FORCE) {
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/* The hash mutex protects the private mount flags. */
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mtx_lock(&fdesc_hashmtx);
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fmp->flags |= FMNT_UNMOUNTF;
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mtx_unlock(&fdesc_hashmtx);
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flags |= FORCECLOSE;
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}
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/*
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* Clear out buffer cache. I don't think we
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* ever get anything cached at this level at the
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* moment, but who knows...
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*
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* There is 1 extra root vnode reference corresponding
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* to f_root.
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*/
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if ((error = vflush(mp, 1, flags, curthread)) != 0)
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return (error);
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/*
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* Finally, throw away the fdescmount structure.
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*/
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mp->mnt_data = NULL;
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free(fmp, M_FDESCMNT);
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return (0);
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}
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static int
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fdesc_root(struct mount *mp, int flags, struct vnode **vpp)
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{
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struct vnode *vp;
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/*
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* Return locked reference to root.
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*/
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vp = VFSTOFDESC(mp)->f_root;
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vget(vp, flags | LK_RETRY);
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*vpp = vp;
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return (0);
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}
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static int
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fdesc_statfs(struct mount *mp, struct statfs *sbp)
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{
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struct thread *td;
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struct filedesc *fdp;
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int lim;
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int i;
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int last;
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int freefd;
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uint64_t limit;
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td = curthread;
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/*
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* Compute number of free file descriptors.
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* [ Strange results will ensue if the open file
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* limit is ever reduced below the current number
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* of open files... ]
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*/
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lim = lim_cur(td, RLIMIT_NOFILE);
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fdp = td->td_proc->p_fd;
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FILEDESC_SLOCK(fdp);
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limit = racct_get_limit(td->td_proc, RACCT_NOFILE);
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if (lim > limit)
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lim = limit;
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last = min(fdp->fd_nfiles, lim);
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freefd = 0;
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for (i = fdp->fd_freefile; i < last; i++)
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if (fdp->fd_ofiles[i].fde_file == NULL)
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freefd++;
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/*
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* Adjust for the fact that the fdesc array may not
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* have been fully allocated yet.
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*/
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if (fdp->fd_nfiles < lim)
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freefd += (lim - fdp->fd_nfiles);
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FILEDESC_SUNLOCK(fdp);
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sbp->f_flags = 0;
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sbp->f_bsize = DEV_BSIZE;
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sbp->f_iosize = DEV_BSIZE;
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sbp->f_blocks = 2; /* 1K to keep df happy */
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sbp->f_bfree = 0;
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sbp->f_bavail = 0;
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sbp->f_files = lim + 1; /* Allow for "." */
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sbp->f_ffree = freefd; /* See comments above */
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return (0);
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}
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static struct vfsops fdesc_vfsops = {
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.vfs_cmount = fdesc_cmount,
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.vfs_init = fdesc_init,
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.vfs_mount = fdesc_mount,
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.vfs_root = fdesc_root,
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.vfs_statfs = fdesc_statfs,
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.vfs_uninit = fdesc_uninit,
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.vfs_unmount = fdesc_unmount,
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};
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VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL);
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