source: rtems/c/src/lib/libc/unmount.c @ c0438add

4.104.114.84.95
Last change on this file since c0438add was 07a3253d, checked in by Joel Sherrill <joel.sherrill@…>, on 11/23/98 at 19:07:58

Added base version of file system infrastructure. This includes a major
overhaul of the RTEMS system call interface. This base file system is
the "In-Memory File System" aka IMFS.

The design and implementation was done by the following people:

+ Joel Sherrill (joel@…)
+ Jennifer Averett (jennifer@…)
+ Steve "Mr Mount" Salitasc (salitasc@…)
+ Kerwin Wade (wade@…)

PROBLEMS
========

+ It is VERY likely that merging this will break the UNIX port. This

can/will be fixed.

+ There is likely some reentrancy/mutual exclusion needed.

+ Eventually, there should be a "mini-IMFS" description table to

eliminate links, symlinks, etc to save memory. All you need to
have "classic RTEMS" functionality is technically directories
and device IO. All the rest could be left out to save memory.

  • Property mode set to 100644
File size: 6.0 KB
Line 
1/*
2 *  unmount() - Unmount a File System
3 *
4 *  This routine is not defined in the POSIX 1003.1b standard but
5 *  in some form is supported on most UNIX and POSIX systems.  This
6 *  routine is necessary to mount instantiations of a file system
7 *  into the file system name space.
8 *
9 *  COPYRIGHT (c) 1989-1998.
10 *  On-Line Applications Research Corporation (OAR).
11 *  Copyright assigned to U.S. Government, 1994.
12 *
13 *  The license and distribution terms for this file may be
14 *  found in the file LICENSE in this distribution or at
15 *  http://www.OARcorp.com/rtems/license.html.
16 *
17 *  $Id$
18 */
19
20#include <sys/types.h>
21#include <sys/stat.h>
22#include <chain.h>
23#include <fcntl.h>
24#include <unistd.h>
25#include <errno.h>
26#include <stdlib.h>
27#include <string.h>
28#include <assert.h>
29
30#include "imfs.h"
31#include "libio_.h"
32
33/*
34 *  Data structures and routines private to mount/unmount pair.
35 */
36
37extern Chain_Control                    rtems_filesystem_mount_table_control;
38extern rtems_filesystem_location_info_t rtems_filesystem_current;
39
40int search_mt_for_mount_point(
41  rtems_filesystem_location_info_t *location_of_mount_point
42);
43
44
45int file_systems_below_this_mountpoint(
46  const char                            *mount_path,
47  rtems_filesystem_location_info_t      *temp_loc,
48  rtems_filesystem_mount_table_entry_t  *temp_mt_entry
49);
50
51/*
52 *  unmount
53 *
54 *  This routine will attempt to unmount the file system that has been
55 *  is mounted a mount_path.  If the operation is successful, 0 will
56 *  be returned to the calling routine.  Otherwise, 1 will be returned.
57 */
58
59int unmount(
60  const char *mount_path
61)
62{
63  int                                   status;
64  rtems_filesystem_location_info_t      temp_loc;
65  rtems_filesystem_mount_table_entry_t  temp_mt_entry;
66  int                                   result;
67
68  /*
69   *  Are there any file systems below the mount_path specified
70   */
71
72  status = file_systems_below_this_mountpoint(
73    mount_path,
74    &temp_loc,
75    &temp_mt_entry
76  );
77
78  if ( status != 0 )
79    return -1;
80
81  /*
82   *  Is the current node reference pointing to a node in the file system
83   *  we are attempting to unmount ?
84   */
85
86  if ( rtems_filesystem_current.mt_entry == temp_loc.mt_entry )
87    set_errno_and_return_minus_one( EBUSY );
88
89  /*
90   *  Run the file descriptor table to determine if there are any file
91   *  descriptors that are currently active and reference nodes in the
92   *  file system that we are trying to unmount
93   */
94
95  if ( rtems_libio_is_open_files_in_fs( temp_loc.mt_entry ) == 1 )
96    set_errno_and_return_minus_one( EBUSY );
97 
98  /*
99   * Allow the file system being mounted on to do its cleanup.
100   * XXX - Did I change these correctly ??? It looks like either I did
101   * XXX   this backwards or the IMFS_unmount and IMFS_fsumount are swaped.
102   * XXX   Add to the mt_point_node unmount to set the mt_entry back to null
103   * XXX   I will step off in space when evaluating past the end of the node.
104   */
105
106  if ( ( temp_mt_entry.mt_point_node.ops->unmount )( temp_loc.mt_entry ) != 0 )
107     return -1;
108
109  /*
110   * Run the unmount function for the subordinate file system.
111   */
112
113  if ( ( temp_mt_entry.mt_fs_root.ops->fsunmount_me )( temp_loc.mt_entry ) != 0 )
114     return -1;
115
116  /*
117   * Allow the file system to clean up.
118   */
119
120  result = (*temp_loc.ops->fsunmount_me)( temp_loc.mt_entry );
121
122  /*
123   *  Extract the mount table entry from the chain
124   */
125
126  Chain_Extract( ( Chain_Node * ) temp_loc.mt_entry );
127
128  /*
129   *  Free the memory associated with the extracted mount table entry.
130   */
131
132  free( temp_loc.mt_entry );
133
134  return result;
135
136}
137
138
139/*
140 *  file_systems_below_this_mountpoint
141 *
142 *  This routine will run through the entries that currently exist in the
143 *  mount table chain. For each entry in the mount table chain it will
144 *  compare the mount tables mt_fs_root to the new_fs_root_node. If any of the
145 *  mount table file system root nodes matches the new file system root node
146 *  this indicates that we are trying to mount a file system that has already
147 *  been mounted. This is not a permitted operation. temp_loc is set to
148 *  the root node of the file system being unmounted.
149 */
150
151int file_systems_below_this_mountpoint(
152  const char                            *mount_path,
153  rtems_filesystem_location_info_t      *temp_loc,
154  rtems_filesystem_mount_table_entry_t  *temp_mt_entry
155)
156{
157  Chain_Node                           *the_node;
158  rtems_filesystem_mount_table_entry_t *the_mount_entry;
159  rtems_filesystem_mount_table_entry_t *current_fs_mt_entry;
160
161  /*
162   *  Is the mount_path even a valid node name in the existing tree?
163   */
164
165  if ( rtems_filesystem_evaluate_path( mount_path, 0x0, temp_loc, TRUE ) )
166    return -1;
167 
168  /*
169   *  Look for the node defined in temp_loc as a mount point in the
170   *  mount table chain.
171   */
172
173  for ( the_node = rtems_filesystem_mount_table_control.first;
174        !Chain_Is_tail( &rtems_filesystem_mount_table_control, the_node );
175        the_node = the_node->next ) {
176
177     the_mount_entry = ( rtems_filesystem_mount_table_entry_t * )the_node;
178     if  (the_mount_entry->mt_point_node.node_access  ==
179          temp_loc->node_access ) {
180        current_fs_mt_entry = the_mount_entry;
181        *temp_loc = current_fs_mt_entry->mt_fs_root;
182        goto after_real_mount_point_found;
183     }
184  }
185  set_errno_and_return_minus_one( EACCES );
186
187
188after_real_mount_point_found:
189
190  for ( the_node = rtems_filesystem_mount_table_control.first;
191        !Chain_Is_tail( &rtems_filesystem_mount_table_control, the_node );
192        the_node = the_node->next ) {
193
194     the_mount_entry = (  rtems_filesystem_mount_table_entry_t * )the_node;
195
196     /*
197      *  Exclude the current file systems mount table entry from the test
198      */
199
200     if ( current_fs_mt_entry != the_mount_entry ) {
201       if ( the_mount_entry->mt_point_node.mt_entry  == current_fs_mt_entry ) {
202
203          /*
204           *  There is at least one fs below the fs on the mount_path.
205           */
206          set_errno_and_return_minus_one( EBUSY );
207       }
208     }
209  }
210
211  *temp_mt_entry = *current_fs_mt_entry;
212
213  return 0;
214}
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