1 files changed, 168 insertions, 9 deletions
diff --git a/Documentation/filesystems/sysv-fs.txt b/Documentation/filesystems/sysv-fs.txt
index d81722418010..253b50d1328e 100644
--- a/Documentation/filesystems/sysv-fs.txt
+++ b/Documentation/filesystems/sysv-fs.txt
@@ -1,11 +1,8 @@
-This is the implementation of the SystemV/Coherent filesystem for Linux.
 It implements all of
  - Xenix FS,
  - SystemV/386 FS,
  - Coherent FS.
-This is version beta 4.
 To install:
 * Answer the 'System V and Coherent filesystem support' question with 'y'
  when configuring the kernel.
@@ -28,11 +25,173 @@ Bugs in the present implementation:
  for this FS on hard disk yet.
-Please report any bugs and suggestions to
+These filesystems are rather similar. Here is a comparison with Minix FS:
-  Bruno Haible <haible@ma2s2.mathematik.uni-karlsruhe.de>
-  Pascal Haible <haible@izfm.uni-stuttgart.de>
+* Linux fdisk reports on partitions
-  Krzysztof G. Baranowski <kgb@manjak.knm.org.pl>
+  - Minix FS     0x81 Linux/Minix
+  - Xenix FS     ??
+  - SystemV FS   ??
+  - Coherent FS  0x08 AIX bootable
+* Size of a block or zone (data allocation unit on disk)
+  - Minix FS     1024
+  - Xenix FS     1024 (also 512 ??)
+  - SystemV FS   1024 (also 512 and 2048)
+  - Coherent FS   512
+* General layout: all have one boot block, one super block and
+  separate areas for inodes and for directories/data.
+  On SystemV Release 2 FS (e.g. Microport) the first track is reserved and
+  all the block numbers (including the super block) are offset by one track.
+* Byte ordering of "short" (16 bit entities) on disk:
+  - Minix FS     little endian  0 1
+  - Xenix FS     little endian  0 1
+  - SystemV FS   little endian  0 1
+  - Coherent FS  little endian  0 1
+  Of course, this affects only the file system, not the data of files on it!
+* Byte ordering of "long" (32 bit entities) on disk:
+  - Minix FS     little endian  0 1 2 3
+  - Xenix FS     little endian  0 1 2 3
+  - SystemV FS   little endian  0 1 2 3
+  - Coherent FS  PDP-11         2 3 0 1
+  Of course, this affects only the file system, not the data of files on it!
+* Inode on disk: "short", 0 means non-existent, the root dir ino is:
+  - Minix FS                            1
+  - Xenix FS, SystemV FS, Coherent FS   2
+* Maximum number of hard links to a file:
+  - Minix FS     250
+  - Xenix FS     ??
+  - SystemV FS   ??
+  - Coherent FS  >=10000
+* Free inode management:
+  - Minix FS                             a bitmap
+  - Xenix FS, SystemV FS, Coherent FS
+      There is a cache of a certain number of free inodes in the super-block.
+      When it is exhausted, new free inodes are found using a linear search.
+* Free block management:
+  - Minix FS                             a bitmap
+  - Xenix FS, SystemV FS, Coherent FS
+      Free blocks are organized in a "free list". Maybe a misleading term,
+      since it is not true that every free block contains a pointer to
+      the next free block. Rather, the free blocks are organized in chunks
+      of limited size, and every now and then a free block contains pointers
+      to the free blocks pertaining to the next chunk; the first of these
+      contains pointers and so on. The list terminates with a "block number"
+      0 on Xenix FS and SystemV FS, with a block zeroed out on Coherent FS.
+* Super-block location:
+  - Minix FS     block 1 = bytes 1024..2047
+  - Xenix FS     block 1 = bytes 1024..2047
+  - SystemV FS   bytes 512..1023
+  - Coherent FS  block 1 = bytes 512..1023
+* Super-block layout:
+  - Minix FS
+                    unsigned short s_ninodes;
+                    unsigned short s_nzones;
+                    unsigned short s_imap_blocks;
+                    unsigned short s_zmap_blocks;
+                    unsigned short s_firstdatazone;
+                    unsigned short s_log_zone_size;
+                    unsigned long s_max_size;
+                    unsigned short s_magic;
+  - Xenix FS, SystemV FS, Coherent FS
+                    unsigned short s_firstdatazone;
+                    unsigned long  s_nzones;
+                    unsigned short s_fzone_count;
+                    unsigned long  s_fzones[NICFREE];
+                    unsigned short s_finode_count;
+                    unsigned short s_finodes[NICINOD];
+                    char           s_flock;
+                    char           s_ilock;
+                    char           s_modified;
+                    char           s_rdonly;
+                    unsigned long  s_time;
+                    short          s_dinfo[4]; -- SystemV FS only
+                    unsigned long  s_free_zones;
+                    unsigned short s_free_inodes;
+                    short          s_dinfo[4]; -- Xenix FS only
+                    unsigned short s_interleave_m,s_interleave_n; -- Coherent FS only
+                    char           s_fname[6];
+                    char           s_fpack[6];
+    then they differ considerably:
+        Xenix FS
+                    char           s_clean;
+                    char           s_fill[371];
+                    long           s_magic;
+                    long           s_type;
+        SystemV FS
+                    long           s_fill[12 or 14];
+                    long           s_state;
+                    long           s_magic;
+                    long           s_type;
+        Coherent FS
+                    unsigned long  s_unique;
+    Note that Coherent FS has no magic.
+* Inode layout:
+  - Minix FS
+                    unsigned short i_mode;
+                    unsigned short i_uid;
+                    unsigned long  i_size;
+                    unsigned long  i_time;
+                    unsigned char  i_gid;
+                    unsigned char  i_nlinks;
+                    unsigned short i_zone[7+1+1];
+  - Xenix FS, SystemV FS, Coherent FS
+                    unsigned short i_mode;
+                    unsigned short i_nlink;
+                    unsigned short i_uid;
+                    unsigned short i_gid;
+                    unsigned long  i_size;
+                    unsigned char  i_zone[3*(10+1+1+1)];
+                    unsigned long  i_atime;
+                    unsigned long  i_mtime;
+                    unsigned long  i_ctime;
+* Regular file data blocks are organized as
+  - Minix FS
+               7 direct blocks
+               1 indirect block (pointers to blocks)
+               1 double-indirect block (pointer to pointers to blocks)
+  - Xenix FS, SystemV FS, Coherent FS
+              10 direct blocks
+               1 indirect block (pointers to blocks)
+               1 double-indirect block (pointer to pointers to blocks)
+               1 triple-indirect block (pointer to pointers to pointers to blocks)
+* Inode size, inodes per block
+  - Minix FS        32   32
+  - Xenix FS        64   16
+  - SystemV FS      64   16
+  - Coherent FS     64    8
+* Directory entry on disk
+  - Minix FS
+                    unsigned short inode;
+                    char name[14/30];
+  - Xenix FS, SystemV FS, Coherent FS
+                    unsigned short inode;
+                    char name[14];
+* Dir entry size, dir entries per block
+  - Minix FS     16/32    64/32
+  - Xenix FS     16       64
+  - SystemV FS   16       64
+  - Coherent FS  16       32
+* How to implement symbolic links such that the host fsck doesn't scream:
+  - Minix FS     normal
+  - Xenix FS     kludge: as regular files with  chmod 1000
+  - SystemV FS   ??
+  - Coherent FS  kludge: as regular files with  chmod 1000
-Bruno Haible
-<haible@ma2s2.mathematik.uni-karlsruhe.de>
+Notation: We often speak of a "block" but mean a zone (the allocation unit)
+and not the disk driver's notion of "block".

diff --git a/Documentation/filesystems/sysv-fs.txt b/Documentation/filesystems/sysv-fs.txt index d81722418010..253b50d1328e 100644 --- a/Documentation/filesystems/sysv-fs.txt +++ b/Documentation/filesystems/sysv-fs.txt
@@ -1,11 +1,8 @@
1	This is the implementation of the SystemV/Coherent filesystem for Linux.
2	It implements all of	1	It implements all of
3	- Xenix FS,	2	- Xenix FS,
4	- SystemV/386 FS,	3	- SystemV/386 FS,
5	- Coherent FS.	4	- Coherent FS.
6		5
7	This is version beta 4.
8
9	To install:	6	To install:
10	* Answer the 'System V and Coherent filesystem support' question with 'y'	7	* Answer the 'System V and Coherent filesystem support' question with 'y'
11	when configuring the kernel.	8	when configuring the kernel.
@@ -28,11 +25,173 @@ Bugs in the present implementation:
28	for this FS on hard disk yet.	25	for this FS on hard disk yet.
29		26
30		27
31	Please report any bugs and suggestions to	28	These filesystems are rather similar. Here is a comparison with Minix FS:
32	Bruno Haible <haible@ma2s2.mathematik.uni-karlsruhe.de>	29
33	Pascal Haible <haible@izfm.uni-stuttgart.de>	30	* Linux fdisk reports on partitions
34	Krzysztof G. Baranowski <kgb@manjak.knm.org.pl>	31	- Minix FS 0x81 Linux/Minix
		32	- Xenix FS ??
		33	- SystemV FS ??
		34	- Coherent FS 0x08 AIX bootable
		35
		36	* Size of a block or zone (data allocation unit on disk)
		37	- Minix FS 1024
		38	- Xenix FS 1024 (also 512 ??)
		39	- SystemV FS 1024 (also 512 and 2048)
		40	- Coherent FS 512
		41
		42	* General layout: all have one boot block, one super block and
		43	separate areas for inodes and for directories/data.
		44	On SystemV Release 2 FS (e.g. Microport) the first track is reserved and
		45	all the block numbers (including the super block) are offset by one track.
		46
		47	* Byte ordering of "short" (16 bit entities) on disk:
		48	- Minix FS little endian 0 1
		49	- Xenix FS little endian 0 1
		50	- SystemV FS little endian 0 1
		51	- Coherent FS little endian 0 1
		52	Of course, this affects only the file system, not the data of files on it!
		53
		54	* Byte ordering of "long" (32 bit entities) on disk:
		55	- Minix FS little endian 0 1 2 3
		56	- Xenix FS little endian 0 1 2 3
		57	- SystemV FS little endian 0 1 2 3
		58	- Coherent FS PDP-11 2 3 0 1
		59	Of course, this affects only the file system, not the data of files on it!
		60
		61	* Inode on disk: "short", 0 means non-existent, the root dir ino is:
		62	- Minix FS 1
		63	- Xenix FS, SystemV FS, Coherent FS 2
		64
		65	* Maximum number of hard links to a file:
		66	- Minix FS 250
		67	- Xenix FS ??
		68	- SystemV FS ??
		69	- Coherent FS >=10000
		70
		71	* Free inode management:
		72	- Minix FS a bitmap
		73	- Xenix FS, SystemV FS, Coherent FS
		74	There is a cache of a certain number of free inodes in the super-block.
		75	When it is exhausted, new free inodes are found using a linear search.
		76
		77	* Free block management:
		78	- Minix FS a bitmap
		79	- Xenix FS, SystemV FS, Coherent FS
		80	Free blocks are organized in a "free list". Maybe a misleading term,
		81	since it is not true that every free block contains a pointer to
		82	the next free block. Rather, the free blocks are organized in chunks
		83	of limited size, and every now and then a free block contains pointers
		84	to the free blocks pertaining to the next chunk; the first of these
		85	contains pointers and so on. The list terminates with a "block number"
		86	0 on Xenix FS and SystemV FS, with a block zeroed out on Coherent FS.
		87
		88	* Super-block location:
		89	- Minix FS block 1 = bytes 1024..2047
		90	- Xenix FS block 1 = bytes 1024..2047
		91	- SystemV FS bytes 512..1023
		92	- Coherent FS block 1 = bytes 512..1023
		93
		94	* Super-block layout:
		95	- Minix FS
		96	unsigned short s_ninodes;
		97	unsigned short s_nzones;
		98	unsigned short s_imap_blocks;
		99	unsigned short s_zmap_blocks;
		100	unsigned short s_firstdatazone;
		101	unsigned short s_log_zone_size;
		102	unsigned long s_max_size;
		103	unsigned short s_magic;
		104	- Xenix FS, SystemV FS, Coherent FS
		105	unsigned short s_firstdatazone;
		106	unsigned long s_nzones;
		107	unsigned short s_fzone_count;
		108	unsigned long s_fzones[NICFREE];
		109	unsigned short s_finode_count;
		110	unsigned short s_finodes[NICINOD];
		111	char s_flock;
		112	char s_ilock;
		113	char s_modified;
		114	char s_rdonly;
		115	unsigned long s_time;
		116	short s_dinfo[4]; -- SystemV FS only
		117	unsigned long s_free_zones;
		118	unsigned short s_free_inodes;
		119	short s_dinfo[4]; -- Xenix FS only
		120	unsigned short s_interleave_m,s_interleave_n; -- Coherent FS only
		121	char s_fname[6];
		122	char s_fpack[6];
		123	then they differ considerably:
		124	Xenix FS
		125	char s_clean;
		126	char s_fill[371];
		127	long s_magic;
		128	long s_type;
		129	SystemV FS
		130	long s_fill[12 or 14];
		131	long s_state;
		132	long s_magic;
		133	long s_type;
		134	Coherent FS
		135	unsigned long s_unique;
		136	Note that Coherent FS has no magic.
		137
		138	* Inode layout:
		139	- Minix FS
		140	unsigned short i_mode;
		141	unsigned short i_uid;
		142	unsigned long i_size;
		143	unsigned long i_time;
		144	unsigned char i_gid;
		145	unsigned char i_nlinks;
		146	unsigned short i_zone[7+1+1];
		147	- Xenix FS, SystemV FS, Coherent FS
		148	unsigned short i_mode;
		149	unsigned short i_nlink;
		150	unsigned short i_uid;
		151	unsigned short i_gid;
		152	unsigned long i_size;
		153	unsigned char i_zone[3*(10+1+1+1)];
		154	unsigned long i_atime;
		155	unsigned long i_mtime;
		156	unsigned long i_ctime;
		157
		158	* Regular file data blocks are organized as
		159	- Minix FS
		160	7 direct blocks
		161	1 indirect block (pointers to blocks)
		162	1 double-indirect block (pointer to pointers to blocks)
		163	- Xenix FS, SystemV FS, Coherent FS
		164	10 direct blocks
		165	1 indirect block (pointers to blocks)
		166	1 double-indirect block (pointer to pointers to blocks)
		167	1 triple-indirect block (pointer to pointers to pointers to blocks)
		168
		169	* Inode size, inodes per block
		170	- Minix FS 32 32
		171	- Xenix FS 64 16
		172	- SystemV FS 64 16
		173	- Coherent FS 64 8
		174
		175	* Directory entry on disk
		176	- Minix FS
		177	unsigned short inode;
		178	char name[14/30];
		179	- Xenix FS, SystemV FS, Coherent FS
		180	unsigned short inode;
		181	char name[14];
		182
		183	* Dir entry size, dir entries per block
		184	- Minix FS 16/32 64/32
		185	- Xenix FS 16 64
		186	- SystemV FS 16 64
		187	- Coherent FS 16 32
		188
		189	* How to implement symbolic links such that the host fsck doesn't scream:
		190	- Minix FS normal
		191	- Xenix FS kludge: as regular files with chmod 1000
		192	- SystemV FS ??
		193	- Coherent FS kludge: as regular files with chmod 1000
35		194
36	Bruno Haible
37	<haible@ma2s2.mathematik.uni-karlsruhe.de>
38		195
		196	Notation: We often speak of a "block" but mean a zone (the allocation unit)
		197	and not the disk driver's notion of "block".