1 /* $NetBSD: vfs_cwd.c,v 1.3 2010/01/08 11:35:10 pooka Exp $ */ 2 3 /*- 4 * Copyright (c) 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* 30 * Current working directory. 31 */ 32 33 #include <sys/cdefs.h> 34 __KERNEL_RCSID(0, "$NetBSD: vfs_cwd.c,v 1.3 2010/01/08 11:35:10 pooka Exp $"); 35 36 #include <sys/param.h> 37 #include <sys/atomic.h> 38 #include <sys/filedesc.h> 39 #include <sys/proc.h> 40 #include <sys/vnode.h> 41 42 static int cwdi_ctor(void *, void *, int); 43 static void cwdi_dtor(void *, void *); 44 45 static pool_cache_t cwdi_cache; 46 47 void 48 cwd_sys_init(void) 49 { 50 51 cwdi_cache = pool_cache_init(sizeof(struct cwdinfo), coherency_unit, 52 0, 0, "cwdi", NULL, IPL_NONE, cwdi_ctor, cwdi_dtor, NULL); 53 KASSERT(cwdi_cache != NULL); 54 } 55 56 /* 57 * Create an initial cwdinfo structure, using the same current and root 58 * directories as curproc. 59 */ 60 struct cwdinfo * 61 cwdinit(void) 62 { 63 struct cwdinfo *cwdi; 64 struct cwdinfo *copy; 65 66 cwdi = pool_cache_get(cwdi_cache, PR_WAITOK); 67 copy = curproc->p_cwdi; 68 69 rw_enter(©->cwdi_lock, RW_READER); 70 cwdi->cwdi_cdir = copy->cwdi_cdir; 71 if (cwdi->cwdi_cdir) 72 vref(cwdi->cwdi_cdir); 73 cwdi->cwdi_rdir = copy->cwdi_rdir; 74 if (cwdi->cwdi_rdir) 75 vref(cwdi->cwdi_rdir); 76 cwdi->cwdi_edir = copy->cwdi_edir; 77 if (cwdi->cwdi_edir) 78 vref(cwdi->cwdi_edir); 79 cwdi->cwdi_cmask = copy->cwdi_cmask; 80 cwdi->cwdi_refcnt = 1; 81 rw_exit(©->cwdi_lock); 82 83 return (cwdi); 84 } 85 86 static int 87 cwdi_ctor(void *arg, void *obj, int flags) 88 { 89 struct cwdinfo *cwdi = obj; 90 91 rw_init(&cwdi->cwdi_lock); 92 93 return 0; 94 } 95 96 static void 97 cwdi_dtor(void *arg, void *obj) 98 { 99 struct cwdinfo *cwdi = obj; 100 101 rw_destroy(&cwdi->cwdi_lock); 102 } 103 104 /* 105 * Make p2 share p1's cwdinfo. 106 */ 107 void 108 cwdshare(struct proc *p2) 109 { 110 struct cwdinfo *cwdi; 111 112 cwdi = curproc->p_cwdi; 113 114 atomic_inc_uint(&cwdi->cwdi_refcnt); 115 p2->p_cwdi = cwdi; 116 } 117 118 /* 119 * Make sure proc has only one reference to its cwdi, creating 120 * a new one if necessary. 121 */ 122 void 123 cwdunshare(struct proc *p) 124 { 125 struct cwdinfo *cwdi = p->p_cwdi; 126 127 if (cwdi->cwdi_refcnt > 1) { 128 cwdi = cwdinit(); 129 cwdfree(p->p_cwdi); 130 p->p_cwdi = cwdi; 131 } 132 } 133 134 /* 135 * Release a cwdinfo structure. 136 */ 137 void 138 cwdfree(struct cwdinfo *cwdi) 139 { 140 141 if (atomic_dec_uint_nv(&cwdi->cwdi_refcnt) > 0) 142 return; 143 144 vrele(cwdi->cwdi_cdir); 145 if (cwdi->cwdi_rdir) 146 vrele(cwdi->cwdi_rdir); 147 if (cwdi->cwdi_edir) 148 vrele(cwdi->cwdi_edir); 149 pool_cache_put(cwdi_cache, cwdi); 150 } 151