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2542 | jermar | 1 | /* |
2 | * Copyright (c) 2007 Jakub Jermar |
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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 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | /** @addtogroup fs |
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30 | * @{ |
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31 | */ |
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32 | |||
33 | /** |
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2590 | jermar | 34 | * @file vfs_mount.c |
2542 | jermar | 35 | * @brief VFS_MOUNT method. |
36 | */ |
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37 | |||
38 | #include <ipc/ipc.h> |
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39 | #include <async.h> |
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40 | #include <errno.h> |
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41 | #include <stdlib.h> |
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42 | #include <string.h> |
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43 | #include <bool.h> |
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44 | #include <futex.h> |
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45 | #include <libadt/list.h> |
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46 | #include "vfs.h" |
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47 | |||
2553 | jermar | 48 | atomic_t rootfs_futex = FUTEX_INITIALIZER; |
2587 | jermar | 49 | vfs_triplet_t rootfs = { |
50 | .fs_handle = 0, |
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51 | .dev_handle = 0, |
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52 | .index = 0, |
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53 | }; |
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2542 | jermar | 54 | |
2587 | jermar | 55 | static int lookup_root(int fs_handle, int dev_handle, vfs_triplet_t *root) |
2552 | jermar | 56 | { |
2587 | jermar | 57 | vfs_pair_t altroot = { |
2552 | jermar | 58 | .fs_handle = fs_handle, |
59 | .dev_handle = dev_handle, |
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60 | }; |
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61 | |||
2553 | jermar | 62 | return vfs_lookup_internal("/", strlen("/"), root, &altroot); |
2552 | jermar | 63 | } |
64 | |||
2542 | jermar | 65 | void vfs_mount(ipc_callid_t rid, ipc_call_t *request) |
66 | { |
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2552 | jermar | 67 | int dev_handle; |
2597 | jermar | 68 | vfs_node_t *mp_node = NULL; |
2552 | jermar | 69 | |
70 | /* |
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71 | * We expect the library to do the device-name to device-handle |
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72 | * translation for us, thus the device handle will arrive as ARG1 |
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73 | * in the request. |
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74 | */ |
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75 | dev_handle = IPC_GET_ARG1(*request); |
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76 | |||
77 | /* |
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78 | * For now, don't make use of ARG2 and ARG3, but they can be used to |
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79 | * carry mount options in the future. |
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80 | */ |
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81 | |||
2657 | jermar | 82 | ipc_callid_t callid; |
83 | size_t size; |
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84 | |||
2552 | jermar | 85 | /* |
86 | * Now, we expect the client to send us data with the name of the file |
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2657 | jermar | 87 | * system. |
2552 | jermar | 88 | */ |
2619 | jermar | 89 | if (!ipc_data_receive(&callid, NULL, &size)) { |
90 | ipc_answer_0(callid, EINVAL); |
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91 | ipc_answer_0(rid, EINVAL); |
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2552 | jermar | 92 | return; |
93 | } |
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94 | |||
95 | /* |
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2657 | jermar | 96 | * Don't receive more than is necessary for storing a full file system |
97 | * name. |
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2552 | jermar | 98 | */ |
2657 | jermar | 99 | if (size < 1 || size > FS_NAME_MAXLEN) { |
2619 | jermar | 100 | ipc_answer_0(callid, EINVAL); |
101 | ipc_answer_0(rid, EINVAL); |
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2552 | jermar | 102 | return; |
103 | } |
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104 | |||
105 | /* |
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2657 | jermar | 106 | * Deliver the file system name. |
2552 | jermar | 107 | */ |
2657 | jermar | 108 | char fs_name[FS_NAME_MAXLEN + 1]; |
109 | (void) ipc_data_deliver(callid, fs_name, size); |
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110 | fs_name[size] = '\0'; |
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111 | |||
112 | /* |
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113 | * Check if we know a file system with the same name as is in fs_name. |
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114 | * This will also give us its file system handle. |
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115 | */ |
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116 | int fs_handle = fs_name_to_handle(fs_name, true); |
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117 | if (!fs_handle) { |
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118 | ipc_answer_0(rid, ENOENT); |
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119 | return; |
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120 | } |
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121 | |||
122 | /* |
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123 | * Now, we want the client to send us the mount point. |
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124 | */ |
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125 | if (!ipc_data_receive(&callid, NULL, &size)) { |
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126 | ipc_answer_0(callid, EINVAL); |
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127 | ipc_answer_0(rid, EINVAL); |
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128 | return; |
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129 | } |
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130 | |||
131 | /* |
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132 | * Check whether size is reasonable wrt. the mount point. |
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133 | */ |
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134 | if (size < 1 || size > MAX_PATH_LEN) { |
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135 | ipc_answer_0(callid, EINVAL); |
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136 | ipc_answer_0(rid, EINVAL); |
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137 | return; |
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138 | } |
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139 | /* |
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140 | * Allocate buffer for the mount point data being received. |
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141 | */ |
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2552 | jermar | 142 | uint8_t *buf; |
143 | buf = malloc(size); |
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144 | if (!buf) { |
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2619 | jermar | 145 | ipc_answer_0(callid, ENOMEM); |
146 | ipc_answer_0(rid, ENOMEM); |
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2552 | jermar | 147 | return; |
148 | } |
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149 | |||
150 | /* |
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2657 | jermar | 151 | * Deliver the mount point. |
2552 | jermar | 152 | */ |
2619 | jermar | 153 | (void) ipc_data_deliver(callid, buf, size); |
2552 | jermar | 154 | |
155 | /* |
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156 | * Lookup the root node of the filesystem being mounted. |
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2597 | jermar | 157 | * In this case, we don't need to take the unlink_futex as the root node |
158 | * cannot be removed. However, we do take a reference to it so that |
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159 | * we can track how many times it has been mounted. |
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2552 | jermar | 160 | */ |
161 | int rc; |
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2587 | jermar | 162 | vfs_triplet_t mounted_root; |
2552 | jermar | 163 | rc = lookup_root(fs_handle, dev_handle, &mounted_root); |
164 | if (rc != EOK) { |
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165 | free(buf); |
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2619 | jermar | 166 | ipc_answer_0(rid, rc); |
2552 | jermar | 167 | return; |
168 | } |
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2597 | jermar | 169 | vfs_node_t *mr_node = vfs_node_get(&mounted_root); |
170 | if (!mr_node) { |
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171 | free(buf); |
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2619 | jermar | 172 | ipc_answer_0(rid, ENOMEM); |
2597 | jermar | 173 | return; |
174 | } |
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2552 | jermar | 175 | |
176 | /* |
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177 | * Finally, we need to resolve the path to the mountpoint. |
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178 | */ |
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2587 | jermar | 179 | vfs_triplet_t mp; |
2553 | jermar | 180 | futex_down(&rootfs_futex); |
2552 | jermar | 181 | if (rootfs.fs_handle) { |
182 | /* |
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183 | * We already have the root FS. |
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184 | */ |
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2597 | jermar | 185 | futex_down(&unlink_futex); |
2657 | jermar | 186 | rc = vfs_lookup_internal(buf, size, &mp, NULL); |
2552 | jermar | 187 | if (rc != EOK) { |
188 | /* |
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189 | * The lookup failed for some reason. |
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190 | */ |
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2597 | jermar | 191 | futex_up(&unlink_futex); |
2553 | jermar | 192 | futex_up(&rootfs_futex); |
2597 | jermar | 193 | vfs_node_put(mr_node); /* failed -> drop reference */ |
2552 | jermar | 194 | free(buf); |
2619 | jermar | 195 | ipc_answer_0(rid, rc); |
2552 | jermar | 196 | return; |
197 | } |
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2597 | jermar | 198 | mp_node = vfs_node_get(&mp); |
199 | if (!mp_node) { |
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200 | futex_up(&unlink_futex); |
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201 | futex_up(&rootfs_futex); |
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202 | vfs_node_put(mr_node); /* failed -> drop reference */ |
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203 | free(buf); |
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2619 | jermar | 204 | ipc_answer_0(rid, ENOMEM); |
2597 | jermar | 205 | return; |
206 | } |
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207 | /* |
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208 | * Now we hold a reference to mp_node. |
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209 | * It will be dropped upon the corresponding VFS_UNMOUNT. |
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210 | * This prevents the mount point from being deleted. |
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211 | */ |
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212 | futex_up(&unlink_futex); |
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2552 | jermar | 213 | } else { |
214 | /* |
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215 | * We still don't have the root file system mounted. |
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216 | */ |
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2657 | jermar | 217 | if ((size == 1) && (buf[0] == '/')) { |
2552 | jermar | 218 | /* |
219 | * For this simple, but important case, we are done. |
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220 | */ |
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221 | rootfs = mounted_root; |
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2553 | jermar | 222 | futex_up(&rootfs_futex); |
2552 | jermar | 223 | free(buf); |
2619 | jermar | 224 | ipc_answer_0(rid, EOK); |
2552 | jermar | 225 | return; |
226 | } else { |
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227 | /* |
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228 | * We can't resolve this without the root filesystem |
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229 | * being mounted first. |
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230 | */ |
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2553 | jermar | 231 | futex_up(&rootfs_futex); |
2552 | jermar | 232 | free(buf); |
2597 | jermar | 233 | vfs_node_put(mr_node); /* failed -> drop reference */ |
2619 | jermar | 234 | ipc_answer_0(rid, ENOENT); |
2552 | jermar | 235 | return; |
236 | } |
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237 | } |
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2553 | jermar | 238 | futex_up(&rootfs_futex); |
239 | |||
2554 | jermar | 240 | free(buf); /* The buffer is not needed anymore. */ |
241 | |||
2552 | jermar | 242 | /* |
243 | * At this point, we have all necessary pieces: file system and device |
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244 | * handles, and we know the mount point VFS node and also the root node |
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245 | * of the file system being mounted. |
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246 | */ |
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2554 | jermar | 247 | |
248 | int phone = vfs_grab_phone(mp.fs_handle); |
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249 | /* Later we can use ARG3 to pass mode/flags. */ |
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250 | aid_t req1 = async_send_3(phone, VFS_MOUNT, (ipcarg_t) mp.dev_handle, |
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251 | (ipcarg_t) mp.index, 0, NULL); |
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252 | /* The second call uses the same method. */ |
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253 | aid_t req2 = async_send_3(phone, VFS_MOUNT, |
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254 | (ipcarg_t) mounted_root.fs_handle, |
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255 | (ipcarg_t) mounted_root.dev_handle, (ipcarg_t) mounted_root.index, |
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256 | NULL); |
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2651 | jermar | 257 | vfs_release_phone(phone); |
2554 | jermar | 258 | |
259 | ipcarg_t rc1; |
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260 | ipcarg_t rc2; |
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261 | async_wait_for(req1, &rc1); |
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262 | async_wait_for(req2, &rc2); |
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263 | |||
2597 | jermar | 264 | if ((rc1 != EOK) || (rc2 != EOK)) { |
265 | /* Mount failed, drop references to mr_node and mp_node. */ |
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266 | vfs_node_put(mr_node); |
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267 | if (mp_node) |
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268 | vfs_node_put(mp_node); |
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269 | } |
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270 | |||
2569 | jermar | 271 | if (rc2 == EOK) |
2619 | jermar | 272 | ipc_answer_0(rid, rc1); |
2569 | jermar | 273 | else if (rc1 == EOK) |
2619 | jermar | 274 | ipc_answer_0(rid, rc2); |
2554 | jermar | 275 | else |
2619 | jermar | 276 | ipc_answer_0(rid, rc1); |
2542 | jermar | 277 | } |
278 | |||
279 | /** |
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280 | * @} |
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281 | */ |