1 | /* |
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2 | * unmount() - Unmount a File System |
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3 | * |
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4 | * This routine is not defined in the POSIX 1003.1b standard but |
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5 | * in some form is supported on most UNIX and POSIX systems. This |
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6 | * routine is necessary to mount instantiations of a file system |
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7 | * into the file system name space. |
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8 | * |
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9 | * COPYRIGHT (c) 1989-1999. |
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10 | * On-Line Applications Research Corporation (OAR). |
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11 | * |
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12 | * The license and distribution terms for this file may be |
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13 | * found in the file LICENSE in this distribution or at |
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14 | * http://www.OARcorp.com/rtems/license.html. |
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15 | * |
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16 | * $Id$ |
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17 | */ |
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18 | |
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19 | #if HAVE_CONFIG_H |
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20 | #include "config.h" |
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21 | #endif |
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22 | |
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23 | #include <sys/types.h> |
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24 | #include <sys/stat.h> |
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25 | #include <chain.h> |
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26 | #include <fcntl.h> |
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27 | #include <unistd.h> |
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28 | #include <errno.h> |
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29 | #include <stdlib.h> |
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30 | #include <string.h> |
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31 | #include <assert.h> |
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32 | |
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33 | #include <rtems/libio_.h> |
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34 | #include <rtems/seterr.h> |
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35 | |
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36 | /* |
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37 | * Data structures and routines private to mount/unmount pair. |
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38 | */ |
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39 | |
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40 | extern Chain_Control rtems_filesystem_mount_table_control; |
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41 | |
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42 | int search_mt_for_mount_point( |
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43 | rtems_filesystem_location_info_t *location_of_mount_point |
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44 | ); |
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45 | |
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46 | rtems_boolean rtems_filesystem_nodes_equal( |
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47 | const rtems_filesystem_location_info_t *loc1, |
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48 | const rtems_filesystem_location_info_t *loc2 |
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49 | ){ |
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50 | return ( loc1->node_access == loc2->node_access ); |
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51 | } |
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52 | |
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53 | |
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54 | /* |
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55 | * file_systems_below_this_mountpoint |
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56 | * |
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57 | * This routine will run through the entries that currently exist in the |
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58 | * mount table chain. For each entry in the mount table chain it will |
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59 | * compare the mount tables mt_fs_root to the new_fs_root_node. If any of the |
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60 | * mount table file system root nodes matches the new file system root node |
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61 | * this indicates that we are trying to mount a file system that has already |
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62 | * been mounted. This is not a permitted operation. temp_loc is set to |
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63 | * the root node of the file system being unmounted. |
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64 | */ |
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65 | |
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66 | rtems_boolean file_systems_below_this_mountpoint( |
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67 | const char *path, |
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68 | rtems_filesystem_location_info_t *fs_root_loc, |
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69 | rtems_filesystem_mount_table_entry_t *fs_to_unmount |
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70 | ) |
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71 | { |
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72 | Chain_Node *the_node; |
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73 | rtems_filesystem_mount_table_entry_t *the_mount_entry; |
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74 | |
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75 | /* |
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76 | * Search the mount table for any mount entries referencing this |
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77 | * mount entry. |
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78 | */ |
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79 | |
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80 | for ( the_node = rtems_filesystem_mount_table_control.first; |
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81 | !Chain_Is_tail( &rtems_filesystem_mount_table_control, the_node ); |
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82 | the_node = the_node->next ) { |
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83 | the_mount_entry = ( rtems_filesystem_mount_table_entry_t * )the_node; |
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84 | if (the_mount_entry->mt_point_node.mt_entry == fs_root_loc->mt_entry ) { |
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85 | return TRUE; |
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86 | } |
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87 | } |
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88 | |
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89 | return FALSE; |
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90 | } |
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91 | |
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92 | /* |
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93 | * unmount |
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94 | * |
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95 | * This routine will attempt to unmount the file system that has been |
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96 | * is mounted a path. If the operation is successful, 0 will |
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97 | * be returned to the calling routine. Otherwise, 1 will be returned. |
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98 | */ |
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99 | |
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100 | int unmount( |
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101 | const char *path |
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102 | ) |
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103 | { |
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104 | rtems_filesystem_location_info_t loc; |
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105 | rtems_filesystem_location_info_t *fs_root_loc; |
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106 | rtems_filesystem_location_info_t *fs_mount_loc; |
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107 | rtems_filesystem_mount_table_entry_t *mt_entry; |
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108 | |
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109 | /* |
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110 | * Get |
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111 | * The root node of the mounted filesytem. |
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112 | * The node for the directory that the fileystem is mounted on. |
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113 | * The mount entry that is being refered to. |
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114 | */ |
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115 | |
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116 | if ( rtems_filesystem_evaluate_path( path, 0x0, &loc, TRUE ) ) |
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117 | return -1; |
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118 | |
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119 | mt_entry = loc.mt_entry; |
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120 | fs_mount_loc = &mt_entry->mt_point_node; |
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121 | fs_root_loc = &mt_entry->mt_fs_root; |
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122 | |
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123 | /* |
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124 | * Verify this is the root node for the file system to be unmounted. |
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125 | */ |
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126 | |
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127 | if ( !rtems_filesystem_nodes_equal( fs_root_loc, &loc) ){ |
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128 | rtems_filesystem_freenode( &loc ); |
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129 | rtems_set_errno_and_return_minus_one( EACCES ); |
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130 | } |
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131 | |
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132 | /* |
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133 | * Free the loc node and just use the nodes from the mt_entry . |
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134 | */ |
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135 | |
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136 | rtems_filesystem_freenode( &loc ); |
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137 | |
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138 | /* |
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139 | * Verify Unmount is supported by both filesystems. |
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140 | */ |
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141 | |
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142 | if ( !fs_mount_loc->ops->unmount_h ) |
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143 | rtems_set_errno_and_return_minus_one( ENOTSUP ); |
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144 | |
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145 | if ( !fs_root_loc->ops->fsunmount_me_h ) |
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146 | rtems_set_errno_and_return_minus_one( ENOTSUP ); |
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147 | |
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148 | |
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149 | /* |
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150 | * Verify the current node is not in this filesystem. |
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151 | * XXX - Joel I have a question here wasn't code added |
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152 | * that made the current node thread based instead |
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153 | * of system based? I thought it was but it doesn't |
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154 | * look like it in this version. |
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155 | */ |
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156 | |
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157 | if ( rtems_filesystem_current.mt_entry == mt_entry ) |
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158 | rtems_set_errno_and_return_minus_one( EBUSY ); |
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159 | |
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160 | /* |
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161 | * Verify there are no file systems below the path specified |
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162 | */ |
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163 | |
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164 | if ( file_systems_below_this_mountpoint( path, fs_root_loc, mt_entry ) != 0 ) |
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165 | rtems_set_errno_and_return_minus_one( EBUSY ); |
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166 | |
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167 | /* |
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168 | * Run the file descriptor table to determine if there are any file |
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169 | * descriptors that are currently active and reference nodes in the |
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170 | * file system that we are trying to unmount |
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171 | */ |
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172 | |
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173 | if ( rtems_libio_is_open_files_in_fs( mt_entry ) == 1 ) |
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174 | rtems_set_errno_and_return_minus_one( EBUSY ); |
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175 | |
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176 | /* |
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177 | * Allow the file system being unmounted on to do its cleanup. |
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178 | * If it fails it will set the errno to the approprate value |
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179 | * and the fileystem will not be modified. |
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180 | */ |
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181 | |
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182 | if (( fs_mount_loc->ops->unmount_h )( mt_entry ) != 0 ) |
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183 | return -1; |
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184 | |
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185 | /* |
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186 | * Allow the mounted filesystem to unmark the use of the root node. |
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187 | * |
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188 | * Run the unmount function for the subordinate file system. |
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189 | * |
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190 | * If we fail to unmount the filesystem remount it on the base filesystems |
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191 | * directory node. |
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192 | * |
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193 | * NOTE: Fatal error is called in a case which should never happen |
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194 | * This was response was questionable but the best we could |
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195 | * come up with. |
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196 | */ |
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197 | |
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198 | if ((fs_root_loc->ops->fsunmount_me_h )( mt_entry ) != 0){ |
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199 | if (( fs_mount_loc->ops->mount_h )( mt_entry ) != 0 ) |
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200 | rtems_fatal_error_occurred( 0 ); |
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201 | return -1; |
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202 | } |
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203 | |
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204 | /* |
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205 | * Extract the mount table entry from the chain |
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206 | */ |
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207 | |
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208 | Chain_Extract( ( Chain_Node * ) mt_entry ); |
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209 | |
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210 | /* |
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211 | * Free the memory node that was allocated in mount |
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212 | * Free the memory associated with the extracted mount table entry. |
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213 | */ |
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214 | |
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215 | rtems_filesystem_freenode( fs_mount_loc ); |
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216 | free( mt_entry ); |
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217 | |
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218 | return 0; |
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219 | } |
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220 | |
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221 | |
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