pseudofs_fileno.c revision 75295
1/*- 2 * Copyright (c) 2001 Dag-Erling Co�dan Sm�rgrav 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer 10 * in this position and unchanged. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * $FreeBSD: head/sys/fs/pseudofs/pseudofs_fileno.c 75295 2001-04-07 19:51:12Z des $ 29 */ 30 31#include <sys/param.h> 32#include <sys/kernel.h> 33#include <sys/systm.h> 34#include <sys/malloc.h> 35#include <sys/mount.h> 36#include <sys/proc.h> 37#include <sys/sbuf.h> 38#include <sys/sysctl.h> 39 40#include <machine/limits.h> 41 42#include <fs/pseudofs/pseudofs.h> 43#include <fs/pseudofs/pseudofs_internal.h> 44 45static MALLOC_DEFINE(M_PFSFILENO, "pseudofs_fileno", "pseudofs fileno bitmap"); 46 47static struct mtx pfs_fileno_mutex; 48 49#define PFS_BITMAP_SIZE 4096 50#define PFS_SLOT_BITS (sizeof(unsigned int) * CHAR_BIT) 51#define PFS_BITMAP_BITS (PFS_BITMAP_SIZE * PFS_SLOT_BITS) 52struct pfs_bitmap { 53 u_int32_t pb_offset; 54 int pb_used; 55 unsigned int pb_bitmap[PFS_BITMAP_SIZE]; 56 struct pfs_bitmap *pb_next; 57}; 58 59/* 60 * Initialization 61 */ 62void 63pfs_fileno_load(void) 64{ 65 mtx_init(&pfs_fileno_mutex, "pseudofs_fileno", MTX_DEF); 66} 67 68/* 69 * Teardown 70 */ 71void 72pfs_fileno_unload(void) 73{ 74 mtx_destroy(&pfs_fileno_mutex); 75} 76 77/* 78 * Initialize fileno bitmap 79 */ 80void 81pfs_fileno_init(struct pfs_info *pi) 82{ 83 struct pfs_bitmap *pb; 84 85 MALLOC(pb, struct pfs_bitmap *, sizeof *pb, 86 M_PFSFILENO, M_WAITOK|M_ZERO); 87 88 mtx_lock(&pi->pi_mutex); 89 90 pb->pb_bitmap[0] = 07; 91 pb->pb_used = 3; 92 pi->pi_bitmap = pb; 93 pi->pi_root->pn_fileno = 2; 94 95 mtx_unlock(&pi->pi_mutex); 96} 97 98/* 99 * Tear down fileno bitmap 100 */ 101void 102pfs_fileno_uninit(struct pfs_info *pi) 103{ 104 struct pfs_bitmap *pb, *npb; 105 int used; 106 107 mtx_lock(&pi->pi_mutex); 108 109 pb = pi->pi_bitmap; 110 pi->pi_bitmap = NULL; 111 112 mtx_unlock(&pi->pi_mutex); 113 114 for (used = 0; pb; pb = npb) { 115 npb = pb->pb_next; 116 used += pb->pb_used; 117 FREE(pb, M_PFSFILENO); 118 } 119 if (used > 2) 120 printf("WARNING: %d file numbers still in use\n", used); 121} 122 123/* 124 * Get the next available file number 125 */ 126static u_int32_t 127pfs_get_fileno(struct pfs_info *pi) 128{ 129 struct pfs_bitmap *pb, *ppb; 130 u_int32_t fileno; 131 unsigned int *p; 132 int i; 133 134 mtx_lock(&pi->pi_mutex); 135 136 /* look for the first page with free bits */ 137 for (ppb = NULL, pb = pi->pi_bitmap; pb; ppb = pb, pb = pb->pb_next) 138 if (pb->pb_used != PFS_BITMAP_BITS) 139 break; 140 141 /* out of pages? */ 142 if (pb == NULL) { 143 mtx_unlock(&pi->pi_mutex); 144 MALLOC(pb, struct pfs_bitmap *, sizeof *pb, 145 M_PFSFILENO, M_WAITOK|M_ZERO); 146 mtx_lock(&pi->pi_mutex); 147 /* protect against possible race */ 148 while (ppb->pb_next) 149 ppb = ppb->pb_next; 150 pb->pb_offset = ppb->pb_offset + PFS_BITMAP_BITS; 151 ppb->pb_next = pb; 152 } 153 154 /* find the first free slot */ 155 for (i = 0; i < PFS_BITMAP_SIZE; ++i) 156 if (pb->pb_bitmap[i] != UINT_MAX) 157 break; 158 159 /* find the first available bit and flip it */ 160 fileno = pb->pb_offset + i * PFS_SLOT_BITS; 161 p = &pb->pb_bitmap[i]; 162 for (i = 0; i < PFS_SLOT_BITS; ++i, ++fileno) 163 if ((*p & (unsigned int)(1 << i)) == 0) 164 break; 165 KASSERT(i < PFS_SLOT_BITS, 166 ("slot has free bits, yet doesn't")); 167 *p |= (unsigned int)(1 << i); 168 ++pb->pb_used; 169 170 mtx_unlock(&pi->pi_mutex); 171 172 return fileno; 173} 174 175/* 176 * Free a file number 177 */ 178static void 179pfs_free_fileno(struct pfs_info *pi, u_int32_t fileno) 180{ 181 struct pfs_bitmap *pb; 182 unsigned int *p; 183 int i; 184 185 mtx_lock(&pi->pi_mutex); 186 187 /* find the right page */ 188 for (pb = pi->pi_bitmap; 189 pb && fileno >= PFS_BITMAP_BITS; 190 pb = pb->pb_next, fileno -= PFS_BITMAP_BITS) 191 /* nothing */ ; 192 KASSERT(pb, 193 ("fileno isn't in any bitmap")); 194 195 /* find the right bit in the right slot and flip it */ 196 p = &pb->pb_bitmap[fileno / PFS_SLOT_BITS]; 197 i = fileno % PFS_SLOT_BITS; 198 KASSERT(*p & (unsigned int)(1 << i), 199 ("fileno is already free")); 200 *p &= ~((unsigned int)(1 << i)); 201 --pb->pb_used; 202 203 mtx_unlock(&pi->pi_mutex); 204} 205 206/* 207 * Allocate a file number 208 */ 209void 210pfs_fileno_alloc(struct pfs_info *pi, struct pfs_node *pn) 211{ 212 /* make sure our parent has a file number */ 213 if (pn->pn_parent && !pn->pn_parent->pn_fileno) 214 pfs_fileno_alloc(pi, pn->pn_parent); 215 216 switch (pn->pn_type) { 217 case pfstype_root: 218 case pfstype_dir: 219 case pfstype_file: 220 case pfstype_symlink: 221 pn->pn_fileno = pfs_get_fileno(pi); 222 break; 223 case pfstype_this: 224 KASSERT(pn->pn_parent != NULL, 225 ("pfstype_this node has no parent")); 226 pn->pn_fileno = pn->pn_parent->pn_fileno; 227 break; 228 case pfstype_parent: 229 KASSERT(pn->pn_parent != NULL, 230 ("pfstype_parent node has no parent")); 231 if (pn->pn_parent == pi->pi_root) { 232 pn->pn_fileno = pn->pn_parent->pn_fileno; 233 break; 234 } 235 KASSERT(pn->pn_parent->pn_parent != NULL, 236 ("pfstype_parent node has no grandparent")); 237 pn->pn_fileno = pn->pn_parent->pn_parent->pn_fileno; 238 break; 239 case pfstype_procdep: 240 KASSERT(1, 241 ("pfs_fileno_alloc() called for pfstype_procdep node")); 242 break; 243 case pfstype_none: 244 KASSERT(1, 245 ("pfs_fileno_alloc() called for pfstype_none node")); 246 break; 247 } 248 249 printf("pfs_fileno_alloc(): %s: ", pi->pi_name); 250 if (pn->pn_parent) { 251 if (pn->pn_parent->pn_parent) { 252 printf("%s/", pn->pn_parent->pn_parent->pn_name); 253 } 254 printf("%s/", pn->pn_parent->pn_name); 255 } 256 printf("%s -> %d\n", pn->pn_name, pn->pn_fileno); 257} 258 259/* 260 * Release a file number 261 */ 262void 263pfs_fileno_free(struct pfs_info *pi, struct pfs_node *pn) 264{ 265 switch (pn->pn_type) { 266 case pfstype_root: 267 case pfstype_dir: 268 case pfstype_file: 269 case pfstype_symlink: 270 pfs_free_fileno(pi, pn->pn_fileno); 271 break; 272 case pfstype_this: 273 case pfstype_parent: 274 /* ignore these, as they don't "own" their file number */ 275 break; 276 case pfstype_procdep: 277 KASSERT(1, 278 ("pfs_fileno_free() called for pfstype_procdep node")); 279 break; 280 case pfstype_none: 281 KASSERT(1, 282 ("pfs_fileno_free() called for pfstype_none node")); 283 break; 284 } 285} 286