source: rtems/doc/filesystem/mounting.t @ fb02e4c4

4.104.114.84.95
Last change on this file since fb02e4c4 was 7441fe2c, checked in by Joel Sherrill <joel.sherrill@…>, on Oct 12, 1999 at 9:54:40 PM

Made many changes to turn the outline into something more like a manual
and less like a collection of notes.

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1@c
2@c  COPYRIGHT (c) 1988-1998.
3@c  On-Line Applications Research Corporation (OAR).
4@c  All rights reserved.
5@c
6@c  $Id$
7@c
8
9@chapter Mounting and Unmounting Filesystems
10
11@section Mount Points
12
13The following is the list of the characteristics of a mount point:
14
15@itemize @bullet
16
17@item The mount point must be a directory. It may have files and other
18directories under it. These files and directories will be hidden when the
19filesystem is mounted.
20
21@item The task must have read/write/execute permissions to the mount point
22or the mount attempt will be rejected.
23
24@item Only one filesystem can be mounted to a single mount point.
25
26@item The Root of the mountable filesystem will be referenced by the name
27of the mount point after the mount is complete.
28
29@end itemize
30
31@section Mount Table Chain
32
33The mount table chain is a dynamic list of structures that describe
34mounted filesystems a specific points in the filesystem hierarchy. It is
35initialized to an empty state during the base filesystem initialization.
36The mount operation will add entries to the mount table chain. The
37un-mount operation will remove entries from the mount table chain.
38
39Each entry in the mount table chain is of the following type:
40
41@example
42struct rtems_filesystem_mount_table_entry_tt
43@{
44   Chain_Node                             Node;
45   rtems_filesystem_location_info_t       mt_point_node;
46   rtems_filesystem_location_info_t       mt_fs_root;
47   int                                    options;
48   void                                  *fs_info;
49
50   rtems_filesystem_limits_and_options_t  pathconf_limits_and_options;
51
52  /*
53   *  When someone adds a mounted filesystem on a real device,
54   *  this will need to be used.
55   *
56   *  The best option long term for this is probably an
57   *  open file descriptor.
58   */
59   char                                  *dev;
60@};
61@end example
62
63@section Adding entries to the chain during mount
64
65When a filesystem is mounted, its presence and location in the file
66system hierarchy is recorded in a dynamic list structure known as a chain.
67A unique rtems_filesystem_mount_table_entry_tt structure is logged for
68each filesystem that is mounted. This includes the base filesystem.
69
70@section Removing entries from the chain during unmount
71
72When a filesystem is dismounted its entry in the mount table chain is
73extracted and the memory for this entry is freed.
74
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