[4d771349] | 1 | @c |
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| 2 | @c COPYRIGHT (c) 1988-1998. |
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| 3 | @c On-Line Applications Research Corporation (OAR). |
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| 4 | @c All rights reserved. |
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| 5 | @c |
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| 6 | @c $Id$ |
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| 7 | @c |
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[9bc1e52a] | 8 | |
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[ffce9b39] | 9 | @chapter Mounting and Unmounting Filesystems |
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[9bc1e52a] | 10 | |
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[ee6284c] | 11 | @section Mount Points |
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| 12 | |
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| 13 | The following is the list of the characteristics of a mount point: |
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| 14 | |
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| 15 | @itemize @bullet |
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| 16 | |
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| 17 | @item The mount point must be a directory. It may have files and other |
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| 18 | directories under it. These files and directories will be hidden when the |
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[7441fe2c] | 19 | filesystem is mounted. |
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[ee6284c] | 20 | |
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| 21 | @item The task must have read/write/execute permissions to the mount point |
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| 22 | or the mount attempt will be rejected. |
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| 23 | |
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[7441fe2c] | 24 | @item Only one filesystem can be mounted to a single mount point. |
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[ee6284c] | 25 | |
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[7441fe2c] | 26 | @item The Root of the mountable filesystem will be referenced by the name |
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[ee6284c] | 27 | of the mount point after the mount is complete. |
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| 28 | |
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| 29 | @end itemize |
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| 30 | |
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| 31 | @section Mount Table Chain |
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| 32 | |
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[7441fe2c] | 33 | The mount table chain is a dynamic list of structures that describe |
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| 34 | mounted filesystems a specific points in the filesystem hierarchy. It is |
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| 35 | initialized to an empty state during the base filesystem initialization. |
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| 36 | The mount operation will add entries to the mount table chain. The |
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| 37 | un-mount operation will remove entries from the mount table chain. |
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| 38 | |
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[ee6284c] | 39 | Each entry in the mount table chain is of the following type: |
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[9bc1e52a] | 40 | |
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[ffce9b39] | 41 | @example |
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[9bc1e52a] | 42 | struct rtems_filesystem_mount_table_entry_tt |
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[4d771349] | 43 | @{ |
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[ee6284c] | 44 | Chain_Node Node; |
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| 45 | rtems_filesystem_location_info_t mt_point_node; |
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| 46 | rtems_filesystem_location_info_t mt_fs_root; |
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| 47 | int options; |
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| 48 | void *fs_info; |
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[9bc1e52a] | 49 | |
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[ee6284c] | 50 | rtems_filesystem_limits_and_options_t pathconf_limits_and_options; |
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[9bc1e52a] | 51 | |
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| 52 | /* |
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| 53 | * When someone adds a mounted filesystem on a real device, |
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| 54 | * this will need to be used. |
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| 55 | * |
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[ee6284c] | 56 | * The best option long term for this is probably an |
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| 57 | * open file descriptor. |
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[9bc1e52a] | 58 | */ |
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[ee6284c] | 59 | char *dev; |
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[4d771349] | 60 | @}; |
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[ffce9b39] | 61 | @end example |
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[9bc1e52a] | 62 | |
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[ee6284c] | 63 | @section Adding entries to the chain during mount |
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| 64 | |
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[7441fe2c] | 65 | When a filesystem is mounted, its presence and location in the file |
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[ee6284c] | 66 | system hierarchy is recorded in a dynamic list structure known as a chain. |
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| 67 | A unique rtems_filesystem_mount_table_entry_tt structure is logged for |
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[7441fe2c] | 68 | each filesystem that is mounted. This includes the base filesystem. |
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[ee6284c] | 69 | |
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| 70 | @section Removing entries from the chain during unmount |
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[9bc1e52a] | 71 | |
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[7441fe2c] | 72 | When a filesystem is dismounted its entry in the mount table chain is |
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[ee6284c] | 73 | extracted and the memory for this entry is freed. |
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[9bc1e52a] | 74 | |
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