[linux-2.6-block.git] / Documentation / filesystems / udf.rst

.. SPDX-License-Identifier: GPL-2.0

===============
UDF file system
===============

If you encounter problems with reading UDF discs using this driver,
please report them according to MAINTAINERS file.

Write support requires a block driver which supports writing.  Currently
dvd+rw drives and media support true random sector writes, and so a udf
filesystem on such devices can be directly mounted read/write.  CD-RW
media however, does not support this.  Instead the media can be formatted
for packet mode using the utility cdrwtool, then the pktcdvd driver can
be bound to the underlying cd device to provide the required buffering
and read-modify-write cycles to allow the filesystem random sector writes
while providing the hardware with only full packet writes.  While not
required for dvd+rw media, use of the pktcdvd driver often enhances
performance due to very poor read-modify-write support supplied internally
by drive firmware.

-------------------------------------------------------------------------------

The following mount options are supported:

	===========	======================================
	gid=		Set the default group.
	umask=		Set the default umask.
	mode=		Set the default file permissions.
	dmode=		Set the default directory permissions.
	uid=		Set the default user.
	bs=		Set the block size.
	unhide		Show otherwise hidden files.
	undelete	Show deleted files in lists.
	adinicb		Embed data in the inode (default)
	noadinicb	Don't embed data in the inode
	shortad		Use short ad's
	longad		Use long ad's (default)
	nostrict	Unset strict conformance
	iocharset=	Set the NLS character set
	===========	======================================

The uid= and gid= options need a bit more explaining.  They will accept a
decimal numeric value and all inodes on that mount will then appear as
belonging to that uid and gid.  Mount options also accept the string "forget".
The forget option causes all IDs to be written to disk as -1 which is a way
of UDF standard to indicate that IDs are not supported for these files .

For typical desktop use of removable media, you should set the ID to that of
the interactively logged on user, and also specify the forget option.  This way
the interactive user will always see the files on the disk as belonging to him.

The remaining are for debugging and disaster recovery:

	=====		================================
	novrs		Skip volume sequence recognition
	=====		================================

The following expect a offset from 0.

	==========	=================================================
	session=	Set the CDROM session (default= last session)
	anchor=		Override standard anchor location. (default= 256)
	lastblock=	Set the last block of the filesystem/
	==========	=================================================

-------------------------------------------------------------------------------


For the latest version and toolset see:
	https://github.com/pali/udftools

Documentation on UDF and ECMA 167 is available FREE from:
	- http://www.osta.org/
	- https://www.ecma-international.org/
Commit	Line	Data
c9817ad5 MCC	1	.. SPDX-License-Identifier: GPL-2.0
	2
	3	===============
	4	UDF file system
	5	===============
1da177e4 LT	6
1da177e4 LT	7	If you encounter problems with reading UDF discs using this driver,
503c3117	8	please report them according to MAINTAINERS file.
1da177e4	9
55aa601e PS	10	Write support requires a block driver which supports writing. Currently
	11	dvd+rw drives and media support true random sector writes, and so a udf
	12	filesystem on such devices can be directly mounted read/write. CD-RW
	13	media however, does not support this. Instead the media can be formatted
	14	for packet mode using the utility cdrwtool, then the pktcdvd driver can
	15	be bound to the underlying cd device to provide the required buffering
	16	and read-modify-write cycles to allow the filesystem random sector writes
	17	while providing the hardware with only full packet writes. While not
	18	required for dvd+rw media, use of the pktcdvd driver often enhances
	19	performance due to very poor read-modify-write support supplied internally
	20	by drive firmware.
1da177e4 LT	21
1da177e4 LT	22	-------------------------------------------------------------------------------
c9817ad5	23
1da177e4 LT	24	The following mount options are supported:
1da177e4 LT	25
c9817ad5	26	=========== ======================================
1da177e4 LT	27	gid= Set the default group.
1da177e4 LT	28	umask= Set the default umask.
7ac9bcd5 MS	29	mode= Set the default file permissions.
7ac9bcd5 MS	30	dmode= Set the default directory permissions.
1da177e4 LT	31	uid= Set the default user.
	32	bs= Set the block size.
	33	unhide Show otherwise hidden files.
	34	undelete Show deleted files in lists.
	35	adinicb Embed data in the inode (default)
	36	noadinicb Don't embed data in the inode
	37	shortad Use short ad's
	38	longad Use long ad's (default)
	39	nostrict Unset strict conformance
	40	iocharset= Set the NLS character set
c9817ad5	41	=========== ======================================
1da177e4	42
0e6b3e5e	43	The uid= and gid= options need a bit more explaining. They will accept a
6ccd5194 JK	44	decimal numeric value and all inodes on that mount will then appear as
	45	belonging to that uid and gid. Mount options also accept the string "forget".
	46	The forget option causes all IDs to be written to disk as -1 which is a way
	47	of UDF standard to indicate that IDs are not supported for these files .
0e6b3e5e	48
6ccd5194 JK	49	For typical desktop use of removable media, you should set the ID to that of
	50	the interactively logged on user, and also specify the forget option. This way
	51	the interactive user will always see the files on the disk as belonging to him.
0e6b3e5e	52
1da177e4 LT	53	The remaining are for debugging and disaster recovery:
1da177e4 LT	54
c9817ad5 MCC	55	===== ================================
	56	novrs Skip volume sequence recognition
	57	===== ================================
1da177e4 LT	58
	59	The following expect a offset from 0.
	60
c9817ad5	61	========== =================================================
1da177e4 LT	62	session= Set the CDROM session (default= last session)
1da177e4 LT	63	anchor= Override standard anchor location. (default= 256)
1da177e4	64	lastblock= Set the last block of the filesystem/
c9817ad5	65	========== =================================================
1da177e4	66
1da177e4 LT	67	-------------------------------------------------------------------------------
	68
	69
	70	For the latest version and toolset see:
503c3117	71	https://github.com/pali/udftools
1da177e4 LT	72
1da177e4 LT	73	Documentation on UDF and ECMA 167 is available FREE from:
c9817ad5	74	- http://www.osta.org/
248727a4	75	- https://www.ecma-international.org/