93bcdfe270
to recycle inodes after a destroy_dev() but not until all mounts have picked up the change. Add support for an overflow table for DEVFS inodes. The static table defaults to 1024 inodes, if that fills, an overflow table of 32k inodes is allocated. Both numbers can be changed at compile time, the size of the overflow table also with the sysctl vfs.devfs.noverflow. Use atomic instructions to barrier between make_dev()/destroy_dev() and the mounts. Add lockmgr() locking of directories for operations accessing or modifying the directory TAILQs. Various nitpicking here and there.
438 lines
10 KiB
C
438 lines
10 KiB
C
#define DEBUG 1
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/*
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* Copyright (c) 2000
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* Poul-Henning Kamp. All rights reserved.
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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. 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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* From: FreeBSD: src/sys/miscfs/kernfs/kernfs_vfsops.c 1.36
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*
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* $FreeBSD$
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*/
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#include "opt_devfs.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/dirent.h>
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#include <sys/conf.h>
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#include <sys/vnode.h>
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#include <sys/proc.h>
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#include <sys/malloc.h>
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#include <sys/sysctl.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <machine/atomic.h>
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#include <fs/devfs/devfs.h>
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static dev_t devfs_inot[NDEVFSINO];
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static dev_t *devfs_overflow;
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static int devfs_ref[NDEVFSINO];
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static int *devfs_refoverflow;
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static int devfs_nextino = 3;
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static int devfs_numino;
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static int devfs_topino;
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static int devfs_noverflowwant = NDEVFSOVERFLOW;
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static int devfs_noverflow;
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static unsigned devfs_generation;
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SYSCTL_NODE(_vfs, OID_AUTO, devfs, CTLFLAG_RW, 0, "DEVFS filesystem");
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SYSCTL_UINT(_vfs_devfs, OID_AUTO, noverflow, CTLFLAG_RW,
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&devfs_noverflowwant, 0, "Size of DEVFS overflow table");
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SYSCTL_UINT(_vfs_devfs, OID_AUTO, generation, CTLFLAG_RD,
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&devfs_generation, 0, "DEVFS generation number");
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SYSCTL_UINT(_vfs_devfs, OID_AUTO, inodes, CTLFLAG_RD,
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&devfs_numino, 0, "DEVFS inodes");
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SYSCTL_UINT(_vfs_devfs, OID_AUTO, topinode, CTLFLAG_RD,
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&devfs_topino, 0, "DEVFS highest inode#");
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static int *
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devfs_itor(int inode)
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{
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if (inode < NDEVFSINO)
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return (&devfs_ref[inode]);
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else if (inode < NDEVFSINO + devfs_noverflow)
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return (&devfs_refoverflow[inode - NDEVFSINO]);
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else
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panic ("YRK!");
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}
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static void
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devfs_dropref(int inode)
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{
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int *ip;
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ip = devfs_itor(inode);
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atomic_add_int(ip, -1);
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}
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static int
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devfs_getref(int inode)
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{
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int *ip, i, j;
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dev_t *dp;
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ip = devfs_itor(inode);
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dp = devfs_itod(inode);
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for (;;) {
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i = *ip;
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j = i + 1;
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if (!atomic_cmpset_int(ip, i, j))
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continue;
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if (*dp != NULL)
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return (1);
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atomic_add_int(ip, -1);
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return(0);
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}
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}
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struct devfs_dirent **
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devfs_itode (struct devfs_mount *dm, int inode)
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{
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if (inode < NDEVFSINO)
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return (&dm->dm_dirent[inode]);
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if (devfs_overflow == NULL)
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return (NULL);
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if (inode < NDEVFSINO + devfs_noverflow)
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return (&dm->dm_overflow[inode - NDEVFSINO]);
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return (NULL);
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}
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dev_t *
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devfs_itod (int inode)
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{
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if (inode < NDEVFSINO)
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return (&devfs_inot[inode]);
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if (devfs_overflow == NULL)
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return (NULL);
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if (inode < NDEVFSINO + devfs_noverflow)
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return (&devfs_overflow[inode - NDEVFSINO]);
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return (NULL);
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}
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void
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devfs_attemptoverflow(int insist)
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{
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dev_t **ot;
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int *or;
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int n, nb;
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/* Check if somebody beat us to it */
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if (devfs_overflow != NULL)
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return;
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ot = NULL;
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or = NULL;
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n = devfs_noverflowwant;
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nb = sizeof (struct dev_t *) * n;
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MALLOC(ot, dev_t **, nb, M_DEVFS, insist ? M_WAITOK : M_NOWAIT);
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if (ot == NULL)
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goto bail;
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bzero(ot, nb);
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nb = sizeof (int) * n;
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MALLOC(or, int *, nb, M_DEVFS, insist ? M_WAITOK : M_NOWAIT);
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if (or == NULL)
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goto bail;
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bzero(or, nb);
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if (!atomic_cmpset_ptr(&devfs_overflow, NULL, ot))
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goto bail;
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devfs_refoverflow = or;
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devfs_noverflow = n;
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printf("DEVFS Overflow table with %d entries allocated when %d in use\n", n, devfs_numino);
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return;
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bail:
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/* Somebody beat us to it, or something went wrong. */
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if (ot != NULL)
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FREE(ot, M_DEVFS);
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if (or != NULL)
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FREE(or, M_DEVFS);
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return;
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}
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struct devfs_dirent *
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devfs_find(struct devfs_dirent *dd, const char *name, int namelen)
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{
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struct devfs_dirent *de;
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TAILQ_FOREACH(de, &dd->de_dlist, de_list) {
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if (namelen != de->de_dirent->d_namlen)
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continue;
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if (bcmp(name, de->de_dirent->d_name, namelen) != 0)
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continue;
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break;
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}
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return (de);
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}
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struct devfs_dirent *
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devfs_newdirent(char *name, int namelen)
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{
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int i;
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struct devfs_dirent *de;
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struct dirent d;
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d.d_namlen = namelen;
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i = sizeof (*de) + GENERIC_DIRSIZ(&d);
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MALLOC(de, struct devfs_dirent *, i, M_DEVFS, M_WAITOK);
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bzero(de, i);
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de->de_dirent = (struct dirent *)(de + 1);
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de->de_dirent->d_namlen = namelen;
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de->de_dirent->d_reclen = GENERIC_DIRSIZ(&d);
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bcopy(name, de->de_dirent->d_name, namelen + 1);
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nanotime(&de->de_ctime);
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de->de_mtime = de->de_atime = de->de_ctime;
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de->de_links = 1;
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return (de);
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}
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struct devfs_dirent *
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devfs_vmkdir(char *name, int namelen, struct devfs_dirent *dotdot)
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{
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struct devfs_dirent *dd;
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struct devfs_dirent *de;
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dd = devfs_newdirent(name, namelen);
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TAILQ_INIT(&dd->de_dlist);
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dd->de_dirent->d_type = DT_DIR;
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dd->de_mode = 0755;
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dd->de_links = 2;
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dd->de_dir = dd;
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de = devfs_newdirent(".", 1);
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de->de_dirent->d_type = DT_DIR;
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de->de_dir = dd;
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de->de_flags |= DE_DOT;
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TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
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de = devfs_newdirent("..", 2);
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de->de_dirent->d_type = DT_DIR;
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if (dotdot == NULL)
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de->de_dir = dd;
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else
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de->de_dir = dotdot;
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de->de_flags |= DE_DOTDOT;
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TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
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return (dd);
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}
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static void
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devfs_delete(struct devfs_dirent *dd, struct devfs_dirent *de)
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{
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if (de->de_symlink) {
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FREE(de->de_symlink, M_DEVFS);
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de->de_symlink = NULL;
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}
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if (de->de_vnode) {
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de->de_vnode->v_data = NULL;
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vdrop(de->de_vnode);
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}
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TAILQ_REMOVE(&dd->de_dlist, de, de_list);
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FREE(de, M_DEVFS);
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}
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void
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devfs_purge(struct devfs_dirent *dd)
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{
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struct devfs_dirent *de;
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for (;;) {
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de = TAILQ_FIRST(&dd->de_dlist);
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if (de == NULL)
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break;
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devfs_delete(dd, de);
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}
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FREE(dd, M_DEVFS);
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}
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int
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devfs_populate(struct devfs_mount *dm)
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{
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int i, j;
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dev_t dev, pdev;
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struct devfs_dirent *dd;
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struct devfs_dirent *de, **dep;
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char *q, *s;
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if (dm->dm_generation == devfs_generation)
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return (0);
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lockmgr(&dm->dm_lock, LK_UPGRADE, 0, curproc);
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if (devfs_noverflow && dm->dm_overflow == NULL) {
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i = devfs_noverflow * sizeof (struct devfs_dirent *);
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MALLOC(dm->dm_overflow, struct devfs_dirent **, i,
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M_DEVFS, M_WAITOK);
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bzero(dm->dm_overflow, i);
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}
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while (dm->dm_generation != devfs_generation) {
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dm->dm_generation = devfs_generation;
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for (i = 0; i <= devfs_topino; i++) {
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dev = *devfs_itod(i);
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dep = devfs_itode(dm, i);
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de = *dep;
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if (dev == NULL && de == DE_DELETED) {
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*dep = NULL;
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continue;
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}
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if (dev == NULL && de != NULL) {
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dd = de->de_dir;
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*dep = NULL;
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TAILQ_REMOVE(&dd->de_dlist, de, de_list);
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if (de->de_vnode) {
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de->de_vnode->v_data = NULL;
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vdrop(de->de_vnode);
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}
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FREE(de, M_DEVFS);
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devfs_dropref(i);
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continue;
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}
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if (dev == NULL)
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continue;
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if (de != NULL)
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continue;
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if (!devfs_getref(i))
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continue;
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dd = dm->dm_basedir;
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s = dev->si_name;
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for (;;) {
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for (q = s; *q != '/' && *q != '\0'; q++)
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continue;
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if (*q != '/')
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break;
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de = devfs_find(dd, s, q - s);
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if (de == NULL) {
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de = devfs_vmkdir(s, q - s, dd);
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de->de_inode = dm->dm_inode++;
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TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
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dd->de_links++;
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}
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s = q + 1;
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dd = de;
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}
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de = devfs_newdirent(s, q - s);
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if (dev->si_flags & SI_ALIAS) {
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de->de_inode = dm->dm_inode++;
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de->de_uid = 0;
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de->de_gid = 0;
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de->de_mode = 0666;
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de->de_dirent->d_type = DT_LNK;
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pdev = dev->si_drv1;
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j = strlen(pdev->si_name) + 1;
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MALLOC(de->de_symlink, char *, j, M_DEVFS, M_WAITOK);
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bcopy(pdev->si_name, de->de_symlink, j);
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} else {
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de->de_inode = i;
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de->de_uid = dev->si_uid;
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de->de_gid = dev->si_gid;
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de->de_mode = dev->si_mode;
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de->de_dirent->d_type = DT_CHR;
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}
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*dep = de;
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de->de_dir = dd;
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TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
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#if 0
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printf("Add ino%d %s\n", i, dev->si_name);
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#endif
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}
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}
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lockmgr(&dm->dm_lock, LK_DOWNGRADE, 0, curproc);
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return (0);
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}
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static void
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devfs_create(dev_t dev)
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{
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int ino, i, *ip;
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dev_t *dp;
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for (;;) {
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/* Grab the next inode number */
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ino = devfs_nextino;
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i = ino + 1;
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/* wrap around when we reach the end */
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if (i >= NDEVFSINO + devfs_noverflow)
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i = 3;
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if (!atomic_cmpset_int(&devfs_nextino, ino, i))
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continue;
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/* see if it was occupied */
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dp = devfs_itod(ino);
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if (dp == NULL)
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Debugger("dp == NULL\n");
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if (*dp != NULL)
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continue;
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ip = devfs_itor(ino);
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if (ip == NULL)
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Debugger("ip == NULL\n");
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if (*ip != 0)
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continue;
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if (!atomic_cmpset_ptr(dp, NULL, dev))
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continue;
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dev->si_inode = ino;
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for (;;) {
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i = devfs_topino;
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if (i >= ino)
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break;
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if (atomic_cmpset_int(&devfs_topino, i, ino))
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break;
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printf("failed topino %d %d\n", i, ino);
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}
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break;
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}
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atomic_add_int(&devfs_numino, 1);
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atomic_add_int(&devfs_generation, 1);
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if (devfs_overflow == NULL && devfs_numino + 100 > NDEVFSINO)
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devfs_attemptoverflow(0);
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}
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static void
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devfs_destroy(dev_t dev)
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{
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int ino, i;
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ino = dev->si_inode;
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dev->si_inode = 0;
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if (ino == 0)
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return;
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if (atomic_cmpset_ptr(devfs_itod(ino), dev, NULL)) {
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atomic_add_int(&devfs_generation, 1);
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atomic_add_int(&devfs_numino, -1);
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i = devfs_nextino;
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if (ino < i)
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atomic_cmpset_int(&devfs_nextino, i, ino);
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}
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}
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devfs_create_t *devfs_create_hook = devfs_create;
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devfs_destroy_t *devfs_destroy_hook = devfs_destroy;
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int devfs_present = 1;
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