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

Documentation/filesystems/sysv-fs.txt

+168 −9
Original line number Diff line number Diff line 
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".

fs/sysv/CHANGES

deleted100644 → 0
+0 −60
Original line number Diff line number Diff line 
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).

fs/sysv/ChangeLog

deleted100644 → 0
+0 −106
Original line number Diff line number Diff line 
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.

fs/sysv/INTRO

deleted100644 → 0
+0 −182
Original line number Diff line number Diff line 
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>

CRA Git | Maintained and supported by SUSTech CRA and CCSE