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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 | |
2687 | jermar | 55 | static int lookup_root(int fs_handle, int dev_handle, vfs_triplet_t *root, |
56 | size_t *size) |
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2552 | jermar | 57 | { |
2587 | jermar | 58 | vfs_pair_t altroot = { |
2552 | jermar | 59 | .fs_handle = fs_handle, |
60 | .dev_handle = dev_handle, |
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61 | }; |
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62 | |||
2687 | jermar | 63 | return vfs_lookup_internal("/", strlen("/"), root, size, &altroot); |
2552 | jermar | 64 | } |
65 | |||
2542 | jermar | 66 | void vfs_mount(ipc_callid_t rid, ipc_call_t *request) |
67 | { |
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2552 | jermar | 68 | int dev_handle; |
2597 | jermar | 69 | vfs_node_t *mp_node = NULL; |
2552 | jermar | 70 | |
71 | /* |
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72 | * We expect the library to do the device-name to device-handle |
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73 | * translation for us, thus the device handle will arrive as ARG1 |
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74 | * in the request. |
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75 | */ |
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76 | dev_handle = IPC_GET_ARG1(*request); |
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77 | |||
78 | /* |
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79 | * For now, don't make use of ARG2 and ARG3, but they can be used to |
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80 | * carry mount options in the future. |
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81 | */ |
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82 | |||
2657 | jermar | 83 | ipc_callid_t callid; |
84 | size_t size; |
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85 | |||
2552 | jermar | 86 | /* |
87 | * Now, we expect the client to send us data with the name of the file |
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2657 | jermar | 88 | * system. |
2552 | jermar | 89 | */ |
2676 | jermar | 90 | if (!ipc_data_write_receive(&callid, &size)) { |
2619 | jermar | 91 | ipc_answer_0(callid, EINVAL); |
92 | ipc_answer_0(rid, EINVAL); |
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2552 | jermar | 93 | return; |
94 | } |
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95 | |||
96 | /* |
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2657 | jermar | 97 | * Don't receive more than is necessary for storing a full file system |
98 | * name. |
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2552 | jermar | 99 | */ |
2657 | jermar | 100 | if (size < 1 || size > FS_NAME_MAXLEN) { |
2619 | jermar | 101 | ipc_answer_0(callid, EINVAL); |
102 | ipc_answer_0(rid, EINVAL); |
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2552 | jermar | 103 | return; |
104 | } |
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105 | |||
106 | /* |
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2657 | jermar | 107 | * Deliver the file system name. |
2552 | jermar | 108 | */ |
2657 | jermar | 109 | char fs_name[FS_NAME_MAXLEN + 1]; |
2678 | jermar | 110 | (void) ipc_data_write_finalize(callid, fs_name, size); |
2657 | jermar | 111 | fs_name[size] = '\0'; |
112 | |||
113 | /* |
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114 | * Check if we know a file system with the same name as is in fs_name. |
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115 | * This will also give us its file system handle. |
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116 | */ |
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117 | int fs_handle = fs_name_to_handle(fs_name, true); |
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118 | if (!fs_handle) { |
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119 | ipc_answer_0(rid, ENOENT); |
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120 | return; |
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121 | } |
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122 | |||
123 | /* |
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124 | * Now, we want the client to send us the mount point. |
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125 | */ |
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2676 | jermar | 126 | if (!ipc_data_write_receive(&callid, &size)) { |
2657 | jermar | 127 | ipc_answer_0(callid, EINVAL); |
128 | ipc_answer_0(rid, EINVAL); |
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129 | return; |
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130 | } |
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131 | |||
132 | /* |
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133 | * Check whether size is reasonable wrt. the mount point. |
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134 | */ |
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135 | if (size < 1 || size > MAX_PATH_LEN) { |
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136 | ipc_answer_0(callid, EINVAL); |
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137 | ipc_answer_0(rid, EINVAL); |
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138 | return; |
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139 | } |
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140 | /* |
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141 | * Allocate buffer for the mount point data being received. |
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142 | */ |
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2552 | jermar | 143 | uint8_t *buf; |
144 | buf = malloc(size); |
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145 | if (!buf) { |
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2619 | jermar | 146 | ipc_answer_0(callid, ENOMEM); |
147 | ipc_answer_0(rid, ENOMEM); |
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2552 | jermar | 148 | return; |
149 | } |
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150 | |||
151 | /* |
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2657 | jermar | 152 | * Deliver the mount point. |
2552 | jermar | 153 | */ |
2678 | jermar | 154 | (void) ipc_data_write_finalize(callid, buf, size); |
2552 | jermar | 155 | |
156 | /* |
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157 | * Lookup the root node of the filesystem being mounted. |
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2679 | jermar | 158 | * In this case, we don't need to take the namespace_futex as the root |
159 | * node cannot be removed. However, we do take a reference to it so |
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160 | * that we can track how many times it has been mounted. |
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2552 | jermar | 161 | */ |
162 | int rc; |
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2587 | jermar | 163 | vfs_triplet_t mounted_root; |
2687 | jermar | 164 | size_t mrsz; |
165 | rc = lookup_root(fs_handle, dev_handle, &mounted_root, &mrsz); |
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2552 | jermar | 166 | if (rc != EOK) { |
167 | free(buf); |
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2619 | jermar | 168 | ipc_answer_0(rid, rc); |
2552 | jermar | 169 | return; |
170 | } |
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2687 | jermar | 171 | vfs_node_t *mr_node = vfs_node_get(&mounted_root, mrsz); |
2597 | jermar | 172 | if (!mr_node) { |
173 | free(buf); |
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2619 | jermar | 174 | ipc_answer_0(rid, ENOMEM); |
2597 | jermar | 175 | return; |
176 | } |
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2552 | jermar | 177 | |
178 | /* |
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179 | * Finally, we need to resolve the path to the mountpoint. |
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180 | */ |
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2587 | jermar | 181 | vfs_triplet_t mp; |
2687 | jermar | 182 | size_t mpsz; |
2553 | jermar | 183 | futex_down(&rootfs_futex); |
2552 | jermar | 184 | if (rootfs.fs_handle) { |
185 | /* |
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186 | * We already have the root FS. |
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187 | */ |
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2681 | jermar | 188 | rwlock_writer_lock(&namespace_rwlock); |
2687 | jermar | 189 | rc = vfs_lookup_internal(buf, size, &mp, &mpsz, NULL); |
2552 | jermar | 190 | if (rc != EOK) { |
191 | /* |
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192 | * The lookup failed for some reason. |
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193 | */ |
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2681 | jermar | 194 | rwlock_writer_unlock(&namespace_rwlock); |
2553 | jermar | 195 | futex_up(&rootfs_futex); |
2597 | jermar | 196 | vfs_node_put(mr_node); /* failed -> drop reference */ |
2552 | jermar | 197 | free(buf); |
2619 | jermar | 198 | ipc_answer_0(rid, rc); |
2552 | jermar | 199 | return; |
200 | } |
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2687 | jermar | 201 | mp_node = vfs_node_get(&mp, mpsz); |
2597 | jermar | 202 | if (!mp_node) { |
2681 | jermar | 203 | rwlock_writer_unlock(&namespace_rwlock); |
2597 | jermar | 204 | futex_up(&rootfs_futex); |
205 | vfs_node_put(mr_node); /* failed -> drop reference */ |
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206 | free(buf); |
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2619 | jermar | 207 | ipc_answer_0(rid, ENOMEM); |
2597 | jermar | 208 | return; |
209 | } |
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210 | /* |
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211 | * Now we hold a reference to mp_node. |
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212 | * It will be dropped upon the corresponding VFS_UNMOUNT. |
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213 | * This prevents the mount point from being deleted. |
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214 | */ |
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2681 | jermar | 215 | rwlock_writer_unlock(&namespace_rwlock); |
2552 | jermar | 216 | } else { |
217 | /* |
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218 | * We still don't have the root file system mounted. |
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219 | */ |
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2657 | jermar | 220 | if ((size == 1) && (buf[0] == '/')) { |
2552 | jermar | 221 | /* |
222 | * For this simple, but important case, we are done. |
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223 | */ |
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224 | rootfs = mounted_root; |
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2553 | jermar | 225 | futex_up(&rootfs_futex); |
2552 | jermar | 226 | free(buf); |
2619 | jermar | 227 | ipc_answer_0(rid, EOK); |
2552 | jermar | 228 | return; |
229 | } else { |
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230 | /* |
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231 | * We can't resolve this without the root filesystem |
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232 | * being mounted first. |
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233 | */ |
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2553 | jermar | 234 | futex_up(&rootfs_futex); |
2552 | jermar | 235 | free(buf); |
2597 | jermar | 236 | vfs_node_put(mr_node); /* failed -> drop reference */ |
2619 | jermar | 237 | ipc_answer_0(rid, ENOENT); |
2552 | jermar | 238 | return; |
239 | } |
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240 | } |
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2553 | jermar | 241 | futex_up(&rootfs_futex); |
242 | |||
2554 | jermar | 243 | free(buf); /* The buffer is not needed anymore. */ |
244 | |||
2552 | jermar | 245 | /* |
246 | * At this point, we have all necessary pieces: file system and device |
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247 | * handles, and we know the mount point VFS node and also the root node |
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248 | * of the file system being mounted. |
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249 | */ |
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2554 | jermar | 250 | |
251 | int phone = vfs_grab_phone(mp.fs_handle); |
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252 | /* Later we can use ARG3 to pass mode/flags. */ |
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253 | aid_t req1 = async_send_3(phone, VFS_MOUNT, (ipcarg_t) mp.dev_handle, |
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254 | (ipcarg_t) mp.index, 0, NULL); |
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255 | /* The second call uses the same method. */ |
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256 | aid_t req2 = async_send_3(phone, VFS_MOUNT, |
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257 | (ipcarg_t) mounted_root.fs_handle, |
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258 | (ipcarg_t) mounted_root.dev_handle, (ipcarg_t) mounted_root.index, |
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259 | NULL); |
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2651 | jermar | 260 | vfs_release_phone(phone); |
2554 | jermar | 261 | |
262 | ipcarg_t rc1; |
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263 | ipcarg_t rc2; |
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264 | async_wait_for(req1, &rc1); |
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265 | async_wait_for(req2, &rc2); |
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266 | |||
2597 | jermar | 267 | if ((rc1 != EOK) || (rc2 != EOK)) { |
268 | /* Mount failed, drop references to mr_node and mp_node. */ |
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269 | vfs_node_put(mr_node); |
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270 | if (mp_node) |
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271 | vfs_node_put(mp_node); |
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272 | } |
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273 | |||
2569 | jermar | 274 | if (rc2 == EOK) |
2619 | jermar | 275 | ipc_answer_0(rid, rc1); |
2569 | jermar | 276 | else if (rc1 == EOK) |
2619 | jermar | 277 | ipc_answer_0(rid, rc2); |
2554 | jermar | 278 | else |
2619 | jermar | 279 | ipc_answer_0(rid, rc1); |
2542 | jermar | 280 | } |
281 | |||
282 | /** |
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283 | * @} |
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284 | */ |