diff options
author | Adrian Bunk <bunk@stusta.de> | 2006-12-06 23:40:01 -0500 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-07 11:39:44 -0500 |
commit | 3982cd99c30285ebc71d405cd8530a3dfb7265de (patch) | |
tree | 288eb99e0c77acb7c58f1820d5579ce161e6a88e /fs/sysv/INTRO | |
parent | f1a60dbf68061e5a5364cbc723786b355637ffd3 (diff) |
[PATCH] fs/sysv/: doc cleanup
Remove two different changelog files from fs/sysv/ and merges the INTRO
file into Documentation/filesystems/sysv-fs.txt
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/sysv/INTRO')
-rw-r--r-- | fs/sysv/INTRO | 182 |
1 files changed, 0 insertions, 182 deletions
diff --git a/fs/sysv/INTRO b/fs/sysv/INTRO deleted file mode 100644 index de4e4d17cac6..000000000000 --- a/fs/sysv/INTRO +++ /dev/null | |||
@@ -1,182 +0,0 @@ | |||
1 | This is the implementation of the SystemV/Coherent filesystem for Linux. | ||
2 | It grew out of separate filesystem implementations | ||
3 | |||
4 | Xenix FS Doug Evans <dje@cygnus.com> June 1992 | ||
5 | SystemV FS Paul B. Monday <pmonday@eecs.wsu.edu> March-June 1993 | ||
6 | Coherent FS B. Haible <haible@ma2s2.mathematik.uni-karlsruhe.de> June 1993 | ||
7 | |||
8 | and was merged together in July 1993. | ||
9 | |||
10 | These filesystems are rather similar. Here is a comparison with Minix FS: | ||
11 | |||
12 | * Linux fdisk reports on partitions | ||
13 | - Minix FS 0x81 Linux/Minix | ||
14 | - Xenix FS ?? | ||
15 | - SystemV FS ?? | ||
16 | - Coherent FS 0x08 AIX bootable | ||
17 | |||
18 | * Size of a block or zone (data allocation unit on disk) | ||
19 | - Minix FS 1024 | ||
20 | - Xenix FS 1024 (also 512 ??) | ||
21 | - SystemV FS 1024 (also 512 and 2048) | ||
22 | - Coherent FS 512 | ||
23 | |||
24 | * General layout: all have one boot block, one super block and | ||
25 | separate areas for inodes and for directories/data. | ||
26 | On SystemV Release 2 FS (e.g. Microport) the first track is reserved and | ||
27 | all the block numbers (including the super block) are offset by one track. | ||
28 | |||
29 | * Byte ordering of "short" (16 bit entities) on disk: | ||
30 | - Minix FS little endian 0 1 | ||
31 | - Xenix FS little endian 0 1 | ||
32 | - SystemV FS little endian 0 1 | ||
33 | - Coherent FS little endian 0 1 | ||
34 | Of course, this affects only the file system, not the data of files on it! | ||
35 | |||
36 | * Byte ordering of "long" (32 bit entities) on disk: | ||
37 | - Minix FS little endian 0 1 2 3 | ||
38 | - Xenix FS little endian 0 1 2 3 | ||
39 | - SystemV FS little endian 0 1 2 3 | ||
40 | - Coherent FS PDP-11 2 3 0 1 | ||
41 | Of course, this affects only the file system, not the data of files on it! | ||
42 | |||
43 | * Inode on disk: "short", 0 means non-existent, the root dir ino is: | ||
44 | - Minix FS 1 | ||
45 | - Xenix FS, SystemV FS, Coherent FS 2 | ||
46 | |||
47 | * Maximum number of hard links to a file: | ||
48 | - Minix FS 250 | ||
49 | - Xenix FS ?? | ||
50 | - SystemV FS ?? | ||
51 | - Coherent FS >=10000 | ||
52 | |||
53 | * Free inode management: | ||
54 | - Minix FS a bitmap | ||
55 | - Xenix FS, SystemV FS, Coherent FS | ||
56 | There is a cache of a certain number of free inodes in the super-block. | ||
57 | When it is exhausted, new free inodes are found using a linear search. | ||
58 | |||
59 | * Free block management: | ||
60 | - Minix FS a bitmap | ||
61 | - Xenix FS, SystemV FS, Coherent FS | ||
62 | Free blocks are organized in a "free list". Maybe a misleading term, | ||
63 | since it is not true that every free block contains a pointer to | ||
64 | the next free block. Rather, the free blocks are organized in chunks | ||
65 | of limited size, and every now and then a free block contains pointers | ||
66 | to the free blocks pertaining to the next chunk; the first of these | ||
67 | contains pointers and so on. The list terminates with a "block number" | ||
68 | 0 on Xenix FS and SystemV FS, with a block zeroed out on Coherent FS. | ||
69 | |||
70 | * Super-block location: | ||
71 | - Minix FS block 1 = bytes 1024..2047 | ||
72 | - Xenix FS block 1 = bytes 1024..2047 | ||
73 | - SystemV FS bytes 512..1023 | ||
74 | - Coherent FS block 1 = bytes 512..1023 | ||
75 | |||
76 | * Super-block layout: | ||
77 | - Minix FS | ||
78 | unsigned short s_ninodes; | ||
79 | unsigned short s_nzones; | ||
80 | unsigned short s_imap_blocks; | ||
81 | unsigned short s_zmap_blocks; | ||
82 | unsigned short s_firstdatazone; | ||
83 | unsigned short s_log_zone_size; | ||
84 | unsigned long s_max_size; | ||
85 | unsigned short s_magic; | ||
86 | - Xenix FS, SystemV FS, Coherent FS | ||
87 | unsigned short s_firstdatazone; | ||
88 | unsigned long s_nzones; | ||
89 | unsigned short s_fzone_count; | ||
90 | unsigned long s_fzones[NICFREE]; | ||
91 | unsigned short s_finode_count; | ||
92 | unsigned short s_finodes[NICINOD]; | ||
93 | char s_flock; | ||
94 | char s_ilock; | ||
95 | char s_modified; | ||
96 | char s_rdonly; | ||
97 | unsigned long s_time; | ||
98 | short s_dinfo[4]; -- SystemV FS only | ||
99 | unsigned long s_free_zones; | ||
100 | unsigned short s_free_inodes; | ||
101 | short s_dinfo[4]; -- Xenix FS only | ||
102 | unsigned short s_interleave_m,s_interleave_n; -- Coherent FS only | ||
103 | char s_fname[6]; | ||
104 | char s_fpack[6]; | ||
105 | then they differ considerably: | ||
106 | Xenix FS | ||
107 | char s_clean; | ||
108 | char s_fill[371]; | ||
109 | long s_magic; | ||
110 | long s_type; | ||
111 | SystemV FS | ||
112 | long s_fill[12 or 14]; | ||
113 | long s_state; | ||
114 | long s_magic; | ||
115 | long s_type; | ||
116 | Coherent FS | ||
117 | unsigned long s_unique; | ||
118 | Note that Coherent FS has no magic. | ||
119 | |||
120 | * Inode layout: | ||
121 | - Minix FS | ||
122 | unsigned short i_mode; | ||
123 | unsigned short i_uid; | ||
124 | unsigned long i_size; | ||
125 | unsigned long i_time; | ||
126 | unsigned char i_gid; | ||
127 | unsigned char i_nlinks; | ||
128 | unsigned short i_zone[7+1+1]; | ||
129 | - Xenix FS, SystemV FS, Coherent FS | ||
130 | unsigned short i_mode; | ||
131 | unsigned short i_nlink; | ||
132 | unsigned short i_uid; | ||
133 | unsigned short i_gid; | ||
134 | unsigned long i_size; | ||
135 | unsigned char i_zone[3*(10+1+1+1)]; | ||
136 | unsigned long i_atime; | ||
137 | unsigned long i_mtime; | ||
138 | unsigned long i_ctime; | ||
139 | |||
140 | * Regular file data blocks are organized as | ||
141 | - Minix FS | ||
142 | 7 direct blocks | ||
143 | 1 indirect block (pointers to blocks) | ||
144 | 1 double-indirect block (pointer to pointers to blocks) | ||
145 | - Xenix FS, SystemV FS, Coherent FS | ||
146 | 10 direct blocks | ||
147 | 1 indirect block (pointers to blocks) | ||
148 | 1 double-indirect block (pointer to pointers to blocks) | ||
149 | 1 triple-indirect block (pointer to pointers to pointers to blocks) | ||
150 | |||
151 | * Inode size, inodes per block | ||
152 | - Minix FS 32 32 | ||
153 | - Xenix FS 64 16 | ||
154 | - SystemV FS 64 16 | ||
155 | - Coherent FS 64 8 | ||
156 | |||
157 | * Directory entry on disk | ||
158 | - Minix FS | ||
159 | unsigned short inode; | ||
160 | char name[14/30]; | ||
161 | - Xenix FS, SystemV FS, Coherent FS | ||
162 | unsigned short inode; | ||
163 | char name[14]; | ||
164 | |||
165 | * Dir entry size, dir entries per block | ||
166 | - Minix FS 16/32 64/32 | ||
167 | - Xenix FS 16 64 | ||
168 | - SystemV FS 16 64 | ||
169 | - Coherent FS 16 32 | ||
170 | |||
171 | * How to implement symbolic links such that the host fsck doesn't scream: | ||
172 | - Minix FS normal | ||
173 | - Xenix FS kludge: as regular files with chmod 1000 | ||
174 | - SystemV FS ?? | ||
175 | - Coherent FS kludge: as regular files with chmod 1000 | ||
176 | |||
177 | |||
178 | Notation: We often speak of a "block" but mean a zone (the allocation unit) | ||
179 | and not the disk driver's notion of "block". | ||
180 | |||
181 | |||
182 | Bruno Haible <haible@ma2s2.mathematik.uni-karlsruhe.de> | ||