Commit 3982cd99 authored by Adrian Bunk's avatar Adrian Bunk Committed by Linus Torvalds
Browse files

[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: default avatarAdrian Bunk <bunk@stusta.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f1a60dbf
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
Bruno Haible <haible@ma2s2.mathematik.uni-karlsruhe.de>
Pascal Haible <haible@izfm.uni-stuttgart.de>
Krzysztof G. Baranowski <kgb@manjak.knm.org.pl>
These filesystems are rather similar. Here is a comparison with Minix FS:
* Linux fdisk reports on partitions
- 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".
Mon, 15 Dec 1997 Krzysztof G. Baranowski <kgb@manjak.knm.org.pl>
* namei.c: struct sysv_dir_inode_operations updated to use dentries.
Fri, 23 Jan 1998 Krzysztof G. Baranowski <kgb@manjak.knm.org.pl>
* inode.c: corrected 1 track offset setting (in sb->sv_block_base).
Originally it was overridden (by setting to zero)
in detected_[xenix,sysv4,sysv2,coherent]. Thanks
to Andrzej Krzysztofowicz <ankry@mif.pg.gda.pl>
for identifying the problem.
Tue, 27 Jan 1998 Krzysztof G. Baranowski <kgb@manjak.knm.org.pl>
* inode.c: added 2048-byte block support to SystemV FS.
Merged detected_bs[512,1024,2048]() into one function:
void detected_bs (u_char type, struct super_block *sb).
Thanks to Andrzej Krzysztofowicz <ankry@mif.pg.gda.pl>
for the patch.
Wed, 4 Feb 1998 Krzysztof G. Baranowski <kgb@manjak.knm.org.pl>
* namei.c: removed static subdir(); is_subdir() from dcache.c
is used instead. Cosmetic changes.
Thu, 3 Dec 1998 Al Viro (viro@parcelfarce.linux.theplanet.co.uk)
* namei.c (sysv_rmdir):
Bugectomy: old check for victim being busy
(inode->i_count) wasn't replaced (with checking
dentry->d_count) and escaped Linus in the last round
of changes. Shot and buried.
Wed, 9 Dec 1998 AV
* namei.c (do_sysv_rename):
Fixed incorrect check for other owners + race.
Removed checks that went to VFS.
* namei.c (sysv_unlink):
Removed checks that went to VFS.
Thu, 10 Dec 1998 AV
* namei.c (do_mknod):
Removed dead code - mknod is never asked to
create a symlink or directory. Incidentially,
it wouldn't do it right if it would be called.
Sat, 26 Dec 1998 KGB
* inode.c (detect_sysv4):
Added detection of expanded s_type field (0x10,
0x20 and 0x30). Forced read-only access in this case.
Sun, 21 Mar 1999 AV
* namei.c (sysv_link):
Fixed i_count usage that resulted in dcache corruption.
* inode.c:
Filled ->delete_inode() method with sysv_delete_inode().
sysv_put_inode() is gone, as it tried to do ->delete_
_inode()'s job.
* ialloc.c: (sysv_free_inode):
Fixed race.
Sun, 30 Apr 1999 AV
* namei.c (sysv_mknod):
Removed dead code (S_IFREG case is now passed to
->create() by VFS).
Thu Feb 14 2002 Andrew Morton <akpm@zip.com.au>
* dir_commit_chunk(): call writeout_one_page() as well as
waitfor_one_page() for IS_SYNC directories, so that we
actually do sync the directory. (forward-port from 2.4).
Thu Feb 7 2002 Alexander Viro <viro@parcelfarce.linux.theplanet.co.uk>
* super.c: switched to ->get_sb()
* ChangeLog: fixed dates ;-)
2002-01-24 David S. Miller <davem@redhat.com>
* inode.c: Include linux/init.h
Mon Jan 21 2002 Alexander Viro <viro@parcelfarce.linux.theplanet.co.uk>
* ialloc.c (sysv_new_inode): zero SYSV_I(inode)->i_data out.
* i_vnode renamed to vfs_inode. Sorry, but let's keep that
consistent.
Sat Jan 19 2002 Christoph Hellwig <hch@infradead.org>
* include/linux/sysv_fs.h (SYSV_I): Get fs-private inode data using
list_entry() instead of inode->u.
* include/linux/sysv_fs_i.h: Add 'struct inode i_vnode' field to
sysv_inode_info structure.
* inode.c: Include <linux/slab.h>, implement alloc_inode/destroy_inode
sop methods, add infrastructure for per-fs inode slab cache.
* super.c (init_sysv_fs): Initialize inode cache, recover properly
in the case of failed register_filesystem for V7.
(exit_sysv_fs): Destroy inode cache.
Sat Jan 19 2002 Christoph Hellwig <hch@infradead.org>
* include/linux/sysv_fs.h: Include <linux/sysv_fs_i.h>, declare SYSV_I().
* dir.c (sysv_find_entry): Use SYSV_I() instead of ->u.sysv_i to
access fs-private inode data.
* ialloc.c (sysv_new_inode): Likewise.
* inode.c (sysv_read_inode): Likewise.
(sysv_update_inode): Likewise.
* itree.c (get_branch): Likewise.
(sysv_truncate): Likewise.
* symlink.c (sysv_readlink): Likewise.
(sysv_follow_link): Likewise.
Fri Jan 4 2002 Alexander Viro <viro@parcelfarce.linux.theplanet.co.uk>
* ialloc.c (sysv_free_inode): Use sb->s_id instead of bdevname().
* inode.c (sysv_read_inode): Likewise.
(sysv_update_inode): Likewise.
(sysv_sync_inode): Likewise.
* super.c (detect_sysv): Likewise.
(complete_read_super): Likewise.
(sysv_read_super): Likewise.
(v7_read_super): Likewise.
Sun Dec 30 2001 Manfred Spraul <manfred@colorfullife.com>
* dir.c (dir_commit_chunk): Do not set dir->i_version.
(sysv_readdir): Likewise.
Thu Dec 27 2001 Alexander Viro <viro@parcelfarce.linux.theplanet.co.uk>
* itree.c (get_block): Use map_bh() to fill out bh_result.
Tue Dec 25 2001 Alexander Viro <viro@parcelfarce.linux.theplanet.co.uk>
* super.c (sysv_read_super): Use sb_set_blocksize() to set blocksize.
(v7_read_super): Likewise.
Tue Nov 27 2001 Alexander Viro <viro@parcelfarce.linux.theplanet.co.uk>
* itree.c (get_block): Change type for iblock argument to sector_t.
* super.c (sysv_read_super): Set s_blocksize early.
(v7_read_super): Likewise.
* balloc.c (sysv_new_block): Use sb_bread(). instead of bread().
(sysv_count_free_blocks): Likewise.
* ialloc.c (sysv_raw_inode): Likewise.
* itree.c (get_branch): Likewise.
(free_branches): Likewise.
* super.c (sysv_read_super): Likewise.
(v7_read_super): Likewise.
Sat Dec 15 2001 Christoph Hellwig <hch@infradead.org>
* inode.c (sysv_read_inode): Mark inode as bad in case of failure.
* super.c (complete_read_super): Check for bad root inode.
Wed Nov 21 2001 Andrew Morton <andrewm@uow.edu.au>
* file.c (sysv_sync_file): Call fsync_inode_data_buffers.
Fri Oct 26 2001 Christoph Hellwig <hch@infradead.org>
* dir.c, ialloc.c, namei.c, include/linux/sysv_fs_i.h:
Implement per-Inode lookup offset cache.
Modelled after Ted's ext2 patch.
Fri Oct 26 2001 Christoph Hellwig <hch@infradead.org>
* inode.c, super.c, include/linux/sysv_fs.h,
include/linux/sysv_fs_sb.h:
Remove symlink faking. Noone really wants to use these as
linux filesystems and native OSes don't support it anyway.
This is the implementation of the SystemV/Coherent filesystem for Linux.
It grew out of separate filesystem implementations
Xenix FS Doug Evans <dje@cygnus.com> June 1992
SystemV FS Paul B. Monday <pmonday@eecs.wsu.edu> March-June 1993
Coherent FS B. Haible <haible@ma2s2.mathematik.uni-karlsruhe.de> June 1993
and was merged together in July 1993.
These filesystems are rather similar. Here is a comparison with Minix FS:
* Linux fdisk reports on partitions
- 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
Notation: We often speak of a "block" but mean a zone (the allocation unit)
and not the disk driver's notion of "block".
Bruno Haible <haible@ma2s2.mathematik.uni-karlsruhe.de>
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