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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 | |||
82 | /* |
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83 | * Now, we expect the client to send us data with the name of the file |
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84 | * system and the path of the mountpoint. |
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85 | */ |
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86 | ipc_callid_t callid; |
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87 | size_t size; |
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2619 | jermar | 88 | if (!ipc_data_receive(&callid, NULL, &size)) { |
89 | ipc_answer_0(callid, EINVAL); |
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90 | ipc_answer_0(rid, EINVAL); |
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2552 | jermar | 91 | return; |
92 | } |
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93 | |||
94 | /* |
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95 | * There is no sense in receiving data that can't hold a single |
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96 | * character of path. We won't accept data that exceed certain limits |
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97 | * either. |
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98 | */ |
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99 | if ((size < FS_NAME_MAXLEN + 1) || |
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100 | (size > FS_NAME_MAXLEN + MAX_PATH_LEN)) { |
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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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107 | * Allocate buffer for the data being received. |
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108 | */ |
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109 | uint8_t *buf; |
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110 | buf = malloc(size); |
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111 | if (!buf) { |
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2619 | jermar | 112 | ipc_answer_0(callid, ENOMEM); |
113 | ipc_answer_0(rid, ENOMEM); |
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2552 | jermar | 114 | return; |
115 | } |
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116 | |||
117 | /* |
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118 | * Deliver the data. |
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119 | */ |
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2619 | jermar | 120 | (void) ipc_data_deliver(callid, buf, size); |
2552 | jermar | 121 | |
122 | char fs_name[FS_NAME_MAXLEN + 1]; |
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123 | memcpy(fs_name, buf, FS_NAME_MAXLEN); |
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124 | fs_name[FS_NAME_MAXLEN] = '\0'; |
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125 | |||
126 | /* |
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127 | * Check if we know a file system with the same name as is in fs_name. |
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128 | * This will also give us its file system handle. |
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129 | */ |
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130 | int fs_handle = fs_name_to_handle(fs_name, true); |
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131 | if (!fs_handle) { |
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132 | free(buf); |
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2619 | jermar | 133 | ipc_answer_0(rid, ENOENT); |
2552 | jermar | 134 | return; |
135 | } |
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136 | |||
137 | /* |
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138 | * Lookup the root node of the filesystem being mounted. |
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2597 | jermar | 139 | * In this case, we don't need to take the unlink_futex as the root node |
140 | * cannot be removed. However, we do take a reference to it so that |
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141 | * we can track how many times it has been mounted. |
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2552 | jermar | 142 | */ |
143 | int rc; |
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2587 | jermar | 144 | vfs_triplet_t mounted_root; |
2552 | jermar | 145 | rc = lookup_root(fs_handle, dev_handle, &mounted_root); |
146 | if (rc != EOK) { |
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147 | free(buf); |
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2619 | jermar | 148 | ipc_answer_0(rid, rc); |
2552 | jermar | 149 | return; |
150 | } |
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2597 | jermar | 151 | vfs_node_t *mr_node = vfs_node_get(&mounted_root); |
152 | if (!mr_node) { |
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153 | free(buf); |
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2619 | jermar | 154 | ipc_answer_0(rid, ENOMEM); |
2597 | jermar | 155 | return; |
156 | } |
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2552 | jermar | 157 | |
158 | /* |
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159 | * Finally, we need to resolve the path to the mountpoint. |
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160 | */ |
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2587 | jermar | 161 | vfs_triplet_t mp; |
2553 | jermar | 162 | futex_down(&rootfs_futex); |
2552 | jermar | 163 | if (rootfs.fs_handle) { |
164 | /* |
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165 | * We already have the root FS. |
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166 | */ |
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2597 | jermar | 167 | futex_down(&unlink_futex); |
2552 | jermar | 168 | rc = vfs_lookup_internal((char *) (buf + FS_NAME_MAXLEN), |
169 | size - FS_NAME_MAXLEN, &mp, NULL); |
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170 | if (rc != EOK) { |
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171 | /* |
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172 | * The lookup failed for some reason. |
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173 | */ |
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2597 | jermar | 174 | futex_up(&unlink_futex); |
2553 | jermar | 175 | futex_up(&rootfs_futex); |
2597 | jermar | 176 | vfs_node_put(mr_node); /* failed -> drop reference */ |
2552 | jermar | 177 | free(buf); |
2619 | jermar | 178 | ipc_answer_0(rid, rc); |
2552 | jermar | 179 | return; |
180 | } |
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2597 | jermar | 181 | mp_node = vfs_node_get(&mp); |
182 | if (!mp_node) { |
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183 | futex_up(&unlink_futex); |
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184 | futex_up(&rootfs_futex); |
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185 | vfs_node_put(mr_node); /* failed -> drop reference */ |
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186 | free(buf); |
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2619 | jermar | 187 | ipc_answer_0(rid, ENOMEM); |
2597 | jermar | 188 | return; |
189 | } |
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190 | /* |
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191 | * Now we hold a reference to mp_node. |
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192 | * It will be dropped upon the corresponding VFS_UNMOUNT. |
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193 | * This prevents the mount point from being deleted. |
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194 | */ |
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195 | futex_up(&unlink_futex); |
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2552 | jermar | 196 | } else { |
197 | /* |
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198 | * We still don't have the root file system mounted. |
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199 | */ |
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2553 | jermar | 200 | if ((size - FS_NAME_MAXLEN == strlen("/")) && |
2552 | jermar | 201 | (buf[FS_NAME_MAXLEN] == '/')) { |
202 | /* |
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203 | * For this simple, but important case, we are done. |
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204 | */ |
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205 | rootfs = mounted_root; |
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2553 | jermar | 206 | futex_up(&rootfs_futex); |
2552 | jermar | 207 | free(buf); |
2619 | jermar | 208 | ipc_answer_0(rid, EOK); |
2552 | jermar | 209 | return; |
210 | } else { |
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211 | /* |
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212 | * We can't resolve this without the root filesystem |
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213 | * being mounted first. |
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214 | */ |
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2553 | jermar | 215 | futex_up(&rootfs_futex); |
2552 | jermar | 216 | free(buf); |
2597 | jermar | 217 | vfs_node_put(mr_node); /* failed -> drop reference */ |
2619 | jermar | 218 | ipc_answer_0(rid, ENOENT); |
2552 | jermar | 219 | return; |
220 | } |
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221 | } |
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2553 | jermar | 222 | futex_up(&rootfs_futex); |
223 | |||
2554 | jermar | 224 | free(buf); /* The buffer is not needed anymore. */ |
225 | |||
2552 | jermar | 226 | /* |
227 | * At this point, we have all necessary pieces: file system and device |
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228 | * handles, and we know the mount point VFS node and also the root node |
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229 | * of the file system being mounted. |
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230 | */ |
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2554 | jermar | 231 | |
232 | int phone = vfs_grab_phone(mp.fs_handle); |
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233 | /* Later we can use ARG3 to pass mode/flags. */ |
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234 | aid_t req1 = async_send_3(phone, VFS_MOUNT, (ipcarg_t) mp.dev_handle, |
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235 | (ipcarg_t) mp.index, 0, NULL); |
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236 | /* The second call uses the same method. */ |
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237 | aid_t req2 = async_send_3(phone, VFS_MOUNT, |
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238 | (ipcarg_t) mounted_root.fs_handle, |
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239 | (ipcarg_t) mounted_root.dev_handle, (ipcarg_t) mounted_root.index, |
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240 | NULL); |
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241 | |||
242 | ipcarg_t rc1; |
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243 | ipcarg_t rc2; |
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244 | async_wait_for(req1, &rc1); |
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245 | async_wait_for(req2, &rc2); |
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246 | vfs_release_phone(phone); |
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247 | |||
2597 | jermar | 248 | if ((rc1 != EOK) || (rc2 != EOK)) { |
249 | /* Mount failed, drop references to mr_node and mp_node. */ |
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250 | vfs_node_put(mr_node); |
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251 | if (mp_node) |
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252 | vfs_node_put(mp_node); |
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253 | } |
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254 | |||
2569 | jermar | 255 | if (rc2 == EOK) |
2619 | jermar | 256 | ipc_answer_0(rid, rc1); |
2569 | jermar | 257 | else if (rc1 == EOK) |
2619 | jermar | 258 | ipc_answer_0(rid, rc2); |
2554 | jermar | 259 | else |
2619 | jermar | 260 | ipc_answer_0(rid, rc1); |
2542 | jermar | 261 | } |
262 | |||
263 | /** |
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264 | * @} |
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265 | */ |