scoutos / prex-0.9.0 / usr / server / fs / vfs / vfs_mount.c @ 03e9c04a
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1 | 03e9c04a | Brad Neuman | /*
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2 | * Copyright (c) 2005-2007, Kohsuke Ohtani
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3 | * All rights reserved.
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4 | *
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5 | * Redistribution and use in source and binary forms, with or without
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6 | * modification, are permitted provided that the following conditions
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7 | * are met:
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8 | * 1. Redistributions of source code must retain the above copyright
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9 | * notice, this list of conditions and the following disclaimer.
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10 | * 2. Redistributions in binary form must reproduce the above copyright
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11 | * notice, this list of conditions and the following disclaimer in the
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12 | * documentation and/or other materials provided with the distribution.
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13 | * 3. Neither the name of the author nor the names of any co-contributors
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14 | * may be used to endorse or promote products derived from this software
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15 | * without specific prior written permission.
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16 | *
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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18 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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19 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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20 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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21 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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22 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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23 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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24 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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25 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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27 | * SUCH DAMAGE.
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28 | */
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29 | |||
30 | /*
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31 | * vfs_mount.c - mount operations
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32 | */
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33 | |||
34 | #include <sys/prex.h> |
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35 | |||
36 | #include <sys/stat.h> |
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37 | #include <sys/vnode.h> |
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38 | #include <sys/file.h> |
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39 | #include <sys/mount.h> |
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40 | #include <sys/dirent.h> |
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41 | #include <sys/list.h> |
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42 | #include <sys/buf.h> |
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43 | |||
44 | #include <limits.h> |
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45 | #include <unistd.h> |
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46 | #include <stdlib.h> |
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47 | #include <string.h> |
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48 | #include <stdio.h> |
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49 | #include <errno.h> |
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50 | #include <fcntl.h> |
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51 | |||
52 | #include "vfs.h" |
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53 | |||
54 | /*
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55 | * List for VFS mount points.
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56 | */
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57 | static struct list mount_list = LIST_INIT(mount_list); |
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58 | |||
59 | /*
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60 | * Global lock to access mount point.
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61 | */
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62 | #if CONFIG_FS_THREADS > 1 |
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63 | static mutex_t mount_lock = MUTEX_INITIALIZER;
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64 | #define MOUNT_LOCK() mutex_lock(&mount_lock)
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65 | #define MOUNT_UNLOCK() mutex_unlock(&mount_lock)
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66 | #else
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67 | #define MOUNT_LOCK()
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68 | #define MOUNT_UNLOCK()
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69 | #endif
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70 | |||
71 | /*
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72 | * Lookup file system.
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73 | */
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74 | static const struct vfssw * |
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75 | fs_getfs(char *name)
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76 | { |
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77 | const struct vfssw *fs; |
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78 | |||
79 | for (fs = vfssw; fs->vs_name; fs++) {
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80 | if (!strncmp(name, fs->vs_name, FSMAXNAMES))
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81 | break;
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82 | } |
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83 | if (!fs->vs_name)
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84 | return NULL; |
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85 | return fs;
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86 | } |
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87 | |||
88 | int
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89 | sys_mount(char *dev, char *dir, char *fsname, int flags, void *data) |
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90 | { |
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91 | const struct vfssw *fs; |
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92 | mount_t mp; |
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93 | list_t head, n; |
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94 | device_t device; |
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95 | vnode_t vp, vp_covered; |
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96 | int error;
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97 | |||
98 | #ifdef DEBUG
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99 | dprintf("VFS: mounting %s at %s\n", fsname, dir);
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100 | #endif
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101 | |||
102 | if (!dir || *dir == '\0') |
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103 | return ENOENT;
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104 | |||
105 | /* Find a file system. */
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106 | if (!(fs = fs_getfs(fsname)))
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107 | return ENODEV; /* No such file system */ |
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108 | |||
109 | /* Open device. NULL can be specified as a device. */
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110 | device = 0;
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111 | if (*dev != '\0') { |
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112 | if (strncmp(dev, "/dev/", 5)) |
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113 | return ENOTBLK;
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114 | if ((error = device_open(dev + 5, DO_RDWR, &device)) != 0) |
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115 | return error;
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116 | } |
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117 | |||
118 | MOUNT_LOCK(); |
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119 | |||
120 | /* Check if device or directory has already been mounted. */
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121 | head = &mount_list; |
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122 | for (n = list_first(head); n != head; n = list_next(n)) {
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123 | mp = list_entry(n, struct mount, m_link);
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124 | if (!strcmp(mp->m_path, dir) ||
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125 | (device && mp->m_dev == (dev_t)device)) { |
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126 | error = EBUSY; /* Already mounted */
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127 | goto err1;
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128 | } |
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129 | } |
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130 | /*
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131 | * Create VFS mount entry.
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132 | */
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133 | if (!(mp = malloc(sizeof(struct mount)))) { |
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134 | error = ENOMEM; |
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135 | goto err1;
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136 | } |
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137 | mp->m_count = 0;
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138 | mp->m_op = fs->vs_op; |
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139 | mp->m_flags = flags; |
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140 | mp->m_dev = (dev_t)device; |
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141 | strlcpy(mp->m_path, dir, sizeof(mp->m_path));
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142 | |||
143 | /*
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144 | * Get vnode to be covered in the upper file system.
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145 | */
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146 | if (*dir == '/' && *(dir + 1) == '\0') { |
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147 | /* Ignore if it mounts to global root directory. */
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148 | vp_covered = NULL;
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149 | } else {
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150 | if ((error = namei(dir, &vp_covered)) != 0) { |
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151 | |||
152 | error = ENOENT; |
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153 | goto err2;
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154 | } |
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155 | if (vp_covered->v_type != VDIR) {
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156 | error = ENOTDIR; |
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157 | goto err3;
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158 | } |
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159 | } |
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160 | mp->m_covered = vp_covered; |
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161 | |||
162 | /*
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163 | * Create a root vnode for this file system.
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164 | */
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165 | if ((vp = vget(mp, "/")) == NULL) { |
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166 | error = ENOMEM; |
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167 | goto err3;
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168 | } |
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169 | vp->v_type = VDIR; |
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170 | vp->v_flags = VROOT; |
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171 | vp->v_mode = S_IFDIR | S_IRUSR | S_IWUSR | S_IXUSR; |
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172 | mp->m_root = vp; |
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173 | |||
174 | /*
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175 | * Call a file system specific routine.
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176 | */
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177 | if ((error = VFS_MOUNT(mp, dev, flags, data)) != 0) |
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178 | goto err4;
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179 | |||
180 | if (mp->m_flags & MNT_RDONLY)
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181 | vp->v_mode &=~S_IWUSR; |
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182 | |||
183 | /*
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184 | * Keep reference count for root/covered vnode.
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185 | */
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186 | vn_unlock(vp); |
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187 | if (vp_covered)
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188 | vn_unlock(vp_covered); |
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189 | |||
190 | /*
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191 | * Insert to mount list
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192 | */
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193 | list_insert(&mount_list, &mp->m_link); |
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194 | MOUNT_UNLOCK(); |
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195 | |||
196 | return 0; /* success */ |
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197 | err4:
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198 | vput(vp); |
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199 | err3:
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200 | if (vp_covered)
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201 | vput(vp_covered); |
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202 | err2:
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203 | free(mp); |
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204 | err1:
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205 | device_close(device); |
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206 | |||
207 | MOUNT_UNLOCK(); |
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208 | return error;
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209 | } |
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210 | |||
211 | int
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212 | sys_umount(char *path)
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213 | { |
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214 | mount_t mp; |
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215 | list_t head, n; |
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216 | int error;
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217 | |||
218 | DPRINTF(VFSDB_SYSCALL, ("sys_umount: path=%s\n", path));
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219 | |||
220 | MOUNT_LOCK(); |
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221 | |||
222 | /* Get mount entry */
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223 | head = &mount_list; |
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224 | for (n = list_first(head); n != head; n = list_next(n)) {
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225 | mp = list_entry(n, struct mount, m_link);
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226 | if (!strcmp(path, mp->m_path))
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227 | break;
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228 | } |
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229 | if (n == head) {
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230 | error = EINVAL; |
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231 | goto out;
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232 | } |
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233 | /*
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234 | * Root fs can not be unmounted.
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235 | */
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236 | if (mp->m_covered == NULL) { |
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237 | error = EINVAL; |
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238 | goto out;
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239 | } |
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240 | if ((error = VFS_UNMOUNT(mp)) != 0) |
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241 | goto out;
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242 | list_remove(&mp->m_link); |
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243 | |||
244 | /* Decrement referece count of root vnode */
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245 | vrele(mp->m_covered); |
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246 | |||
247 | /* Release all vnodes */
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248 | vflush(mp); |
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249 | |||
250 | /* Flush all buffers */
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251 | binval(mp->m_dev); |
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252 | |||
253 | if (mp->m_dev)
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254 | device_close((device_t)mp->m_dev); |
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255 | free(mp); |
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256 | out:
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257 | MOUNT_UNLOCK(); |
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258 | return error;
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259 | } |
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260 | |||
261 | int
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262 | sys_sync(void)
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263 | { |
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264 | mount_t mp; |
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265 | list_t head, n; |
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266 | |||
267 | /* Call each mounted file system. */
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268 | MOUNT_LOCK(); |
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269 | head = &mount_list; |
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270 | for (n = list_first(head); n != head; n = list_next(n)) {
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271 | mp = list_entry(n, struct mount, m_link);
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272 | VFS_SYNC(mp); |
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273 | } |
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274 | MOUNT_UNLOCK(); |
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275 | bio_sync(); |
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276 | return 0; |
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277 | } |
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278 | |||
279 | /*
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280 | * Compare two path strings. Return matched length.
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281 | * @path: target path.
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282 | * @root: vfs root path as mount point.
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283 | */
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284 | static size_t
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285 | count_match(char *path, char *mount_root) |
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286 | { |
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287 | size_t len = 0;
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288 | |||
289 | while (*path && *mount_root) {
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290 | if (*path++ != *mount_root++)
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291 | break;
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292 | len++; |
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293 | } |
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294 | if (*mount_root != '\0') |
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295 | return 0; |
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296 | |||
297 | if (len == 1 && *(path - 1) == '/') |
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298 | return 1; |
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299 | |||
300 | if (*path == '\0' || *path == '/') |
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301 | return len;
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302 | return 0; |
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303 | } |
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304 | |||
305 | /*
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306 | * Get the root directory and mount point for specified path.
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307 | * @path: full path.
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308 | * @mp: mount point to return.
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309 | * @root: pointer to root directory in path.
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310 | */
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311 | int
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312 | vfs_findroot(char *path, mount_t *mp, char **root) |
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313 | { |
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314 | mount_t m, tmp; |
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315 | list_t head, n; |
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316 | size_t len, max_len = 0;
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317 | |||
318 | if (!path)
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319 | return -1; |
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320 | |||
321 | /* Find mount point from nearest path */
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322 | MOUNT_LOCK(); |
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323 | m = NULL;
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324 | head = &mount_list; |
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325 | for (n = list_first(head); n != head; n = list_next(n)) {
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326 | tmp = list_entry(n, struct mount, m_link);
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327 | len = count_match(path, tmp->m_path); |
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328 | if (len > max_len) {
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329 | max_len = len; |
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330 | m = tmp; |
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331 | } |
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332 | } |
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333 | MOUNT_UNLOCK(); |
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334 | if (m == NULL) |
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335 | return -1; |
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336 | *root = (char *)(path + max_len);
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337 | if (**root == '/') |
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338 | (*root)++; |
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339 | *mp = m; |
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340 | return 0; |
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341 | } |
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342 | |||
343 | /*
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344 | * Mark a mount point as busy.
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345 | */
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346 | void
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347 | vfs_busy(mount_t mp) |
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348 | { |
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349 | |||
350 | MOUNT_LOCK(); |
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351 | mp->m_count++; |
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352 | MOUNT_UNLOCK(); |
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353 | } |
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354 | |||
355 | |||
356 | /*
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357 | * Mark a mount point as busy.
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358 | */
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359 | void
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360 | vfs_unbusy(mount_t mp) |
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361 | { |
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362 | |||
363 | MOUNT_LOCK(); |
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364 | mp->m_count--; |
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365 | MOUNT_UNLOCK(); |
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366 | } |
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367 | |||
368 | int
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369 | vfs_nullop(void)
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370 | { |
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371 | return 0; |
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372 | } |
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373 | |||
374 | int
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375 | vfs_einval(void)
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376 | { |
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377 | return EINVAL;
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378 | } |
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379 | |||
380 | #ifdef DEBUG_VFS
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381 | void
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382 | mount_dump(void)
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383 | { |
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384 | list_t head, n; |
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385 | mount_t mp; |
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386 | |||
387 | MOUNT_LOCK(); |
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388 | |||
389 | dprintf("mount_dump\n");
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390 | dprintf("dev count root\n");
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391 | dprintf("-------- ----- --------\n");
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392 | head = &mount_list; |
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393 | for (n = list_first(head); n != head; n = list_next(n)) {
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394 | mp = list_entry(n, struct mount, m_link);
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395 | dprintf("%8x %5d %s\n", mp->m_dev, mp->m_count, mp->m_path);
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396 | } |
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397 | MOUNT_UNLOCK(); |
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398 | } |
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399 | #endif |