[PATCH] Docs update: small spelling, formating etc fixes for filesystems/ext3.txt (c63ca3c8) · Commits · e / devices / android_kernel_fairphone_FP3

Documentation/filesystems/ext3.txt

+90 −88

Original line number	Original line	Diff line number	Diff line
	@@ -2,11 +2,11 @@
	Ext3 Filesystem		Ext3 Filesystem
	===============		===============

	ext3 was originally released in September 1999. Written by Stephen Tweedie		Ext3 was originally released in September 1999. Written by Stephen Tweedie
	for 2.2 branch, and ported to 2.4 kernels by Peter Braam, Andreas Dilger,		for the 2.2 branch, and ported to 2.4 kernels by Peter Braam, Andreas Dilger,
	Andrew Morton, Alexander Viro, Ted Ts'o and Stephen Tweedie.		Andrew Morton, Alexander Viro, Ted Ts'o and Stephen Tweedie.

	ext3 is ext2 filesystem enhanced with journalling capabilities.		Ext3 is the ext2 filesystem enhanced with journalling capabilities.

	Options		Options
	=======		=======
	@@ -14,69 +14,71 @@ Options
	When mounting an ext3 filesystem, the following option are accepted:		When mounting an ext3 filesystem, the following option are accepted:
	(*) == default		(*) == default

	jounal=update Update the ext3 file system's journal to the		journal=update Update the ext3 file system's journal to the current
	current format.		format.

	journal=inum When a journal already exists, this option is		journal=inum When a journal already exists, this option is ignored.
	ignored. Otherwise, it specifies the number of		Otherwise, it specifies the number of the inode which
	the inode which will represent the ext3 file		will represent the ext3 file system's journal file.
	system's journal file.

	journal_dev=devnum When the external journal device's major/minor numbers		journal_dev=devnum When the external journal device's major/minor numbers
	have changed, this option allows to specify the new		have changed, this option allows the user to specify
	journal location. The journal device is identified		the new journal location. The journal device is
	through its new major/minor numbers encoded in devnum.		identified through its new major/minor numbers encoded
			in devnum.

	noload Don't load the journal on mounting.		noload Don't load the journal on mounting.

	data=journal All data are committed into the journal prior		data=journal All data are committed into the journal prior to being
	to being written into the main file system.		written into the main file system.

	data=ordered (*) All data are forced directly out to the main file		data=ordered (*) All data are forced directly out to the main file
	system prior to its metadata being committed to		system prior to its metadata being committed to the
	the journal.		journal.

	data=writeback Data ordering is not preserved, data may be		data=writeback Data ordering is not preserved, data may be written
	written into the main file system after its		into the main file system after its metadata has been
	metadata has been committed to the journal.		committed to the journal.

	commit=nrsec (*) Ext3 can be told to sync all its data and metadata		commit=nrsec (*) Ext3 can be told to sync all its data and metadata
	every 'nrsec' seconds. The default value is 5 seconds.		every 'nrsec' seconds. The default value is 5 seconds.
	This means that if you lose your power, you will lose,		This means that if you lose your power, you will lose
	as much, the latest 5 seconds of work (your filesystem		as much as the latest 5 seconds of work (your
	will not be damaged though, thanks to journaling). This		filesystem will not be damaged though, thanks to the
	default value (or any low value) will hurt performance,		journaling). This default value (or any low value)
	but it's good for data-safety. Setting it to 0 will		will hurt performance, but it's good for data-safety.
	have the same effect than leaving the default 5 sec.		Setting it to 0 will have the same effect as leaving
			it at the default (5 seconds).
	Setting it to very large values will improve		Setting it to very large values will improve
	performance.		performance.

	barrier=1 This enables/disables barriers. barrier=0 disables it,		barrier=1 This enables/disables barriers. barrier=0 disables
	barrier=1 enables it.		it, barrier=1 enables it.

	orlov (*) This enables the new Orlov block allocator. It's enabled		orlov (*) This enables the new Orlov block allocator. It is
	by default.		enabled by default.

	oldalloc This disables the Orlov block allocator and enables the		oldalloc This disables the Orlov block allocator and enables
	old block allocator. Orlov should have better performance,		the old block allocator. Orlov should have better
	we'd like to get some feedback if it's the contrary for		performance - we'd like to get some feedback if it's
	you.		the contrary for you.

	user_xattr Enables Extended User Attributes. Additionally, you need		user_xattr Enables Extended User Attributes. Additionally, you
	to have extended attribute support enabled in the kernel		need to have extended attribute support enabled in the
	configuration (CONFIG_EXT3_FS_XATTR). See the attr(5)		kernel configuration (CONFIG_EXT3_FS_XATTR). See the
	manual page and http://acl.bestbits.at to learn more		attr(5) manual page and http://acl.bestbits.at/ to
	about extended attributes.		learn more about extended attributes.

	nouser_xattr Disables Extended User Attributes.		nouser_xattr Disables Extended User Attributes.

	acl Enables POSIX Access Control Lists support. Additionally,		acl Enables POSIX Access Control Lists support.
	you need to have ACL support enabled in the kernel		Additionally, you need to have ACL support enabled in
	configuration (CONFIG_EXT3_FS_POSIX_ACL). See the acl(5)		the kernel configuration (CONFIG_EXT3_FS_POSIX_ACL).
	manual page and http://acl.bestbits.at for more		See the acl(5) manual page and http://acl.bestbits.at/
	information.		for more information.

	noacl This option disables POSIX Access Control List support.		noacl This option disables POSIX Access Control List
			support.

	reservation		reservation

	@@ -108,81 +110,81 @@ resuid=n The user ID which may use the reserved blocks.

	sb=n Use alternate superblock at this location.		sb=n Use alternate superblock at this location.

	quota Quota options are currently silently ignored.		quota
	noquota (see fs/ext3/super.c, line 594)		noquota
	grpquota		grpquota
	usrquota		usrquota


	Specification		Specification
	=============		=============
	ext3 shares all disk implementation with ext2 filesystem, and add		Ext3 shares all disk implementation with the ext2 filesystem, and adds
	transactions capabilities to ext2. Journaling is done by the		transactions capabilities to ext2. Journaling is done by the Journaling Block
	Journaling block device layer.		Device layer.

	Journaling Block Device layer		Journaling Block Device layer
	-----------------------------		-----------------------------
	The Journaling Block Device layer (JBD) isn't ext3 specific. It was		The Journaling Block Device layer (JBD) isn't ext3 specific. It was design to
	design to add journaling capabilities on a block device. The ext3		add journaling capabilities on a block device. The ext3 filesystem code will
	filesystem code will inform the JBD of modifications it is performing		inform the JBD of modifications it is performing (called a transaction). The
	(Call a transaction). the journal support the transactions start and		journal supports the transactions start and stop, and in case of crash, the
	stop, and in case of crash, the journal can replayed the transactions		journal can replayed the transactions to put the partition back in a
	to put the partition on a consistent state fastly.		consistent state fast.

	handles represent a single atomic update to a filesystem. JBD can		Handles represent a single atomic update to a filesystem. JBD can handle an
	handle external journal on a block device.		external journal on a block device.

	Data Mode		Data Mode
	---------		---------
	There's 3 different data modes:		There are 3 different data modes:

	* writeback mode		* writeback mode
	In data=writeback mode, ext3 does not journal data at all. This mode		In data=writeback mode, ext3 does not journal data at all. This mode provides
	provides a similar level of journaling as XFS, JFS, and ReiserFS in its		a similar level of journaling as that of XFS, JFS, and ReiserFS in its default
	default mode - metadata journaling. A crash+recovery can cause		mode - metadata journaling. A crash+recovery can cause incorrect data to
	incorrect data to appear in files which were written shortly before the		appear in files which were written shortly before the crash. This mode will
	crash. This mode will typically provide the best ext3 performance.		typically provide the best ext3 performance.

	* ordered mode		* ordered mode
	In data=ordered mode, ext3 only officially journals metadata, but it		In data=ordered mode, ext3 only officially journals metadata, but it logically
	logically groups metadata and data blocks into a single unit called a		groups metadata and data blocks into a single unit called a transaction. When
	transaction. When it's time to write the new metadata out to disk, the		it's time to write the new metadata out to disk, the associated data blocks
	associated data blocks are written first. In general, this mode		are written first. In general, this mode performs slightly slower than
	perform slightly slower than writeback but significantly faster than		writeback but significantly faster than journal mode.
	journal mode.

	* journal mode		* journal mode
	data=journal mode provides full data and metadata journaling. All new		data=journal mode provides full data and metadata journaling. All new data is
	data is written to the journal first, and then to its final location.		written to the journal first, and then to its final location.
	In the event of a crash, the journal can be replayed, bringing both		In the event of a crash, the journal can be replayed, bringing both data and
	data and metadata into a consistent state. This mode is the slowest		metadata into a consistent state. This mode is the slowest except when data
	except when data needs to be read from and written to disk at the same		needs to be read from and written to disk at the same time where it
	time where it outperform all others mode.		outperforms all others modes.

	Compatibility		Compatibility
	-------------		-------------

	Ext2 partitions can be easily convert to ext3, with `tune2fs -j <dev>`.		Ext2 partitions can be easily convert to ext3, with `tune2fs -j <dev>`.
	Ext3 is fully compatible with Ext2. Ext3 partitions can easily be		Ext3 is fully compatible with Ext2. Ext3 partitions can easily be mounted as
	mounted as Ext2.		Ext2.


	External Tools		External Tools
	==============		==============
	see manual pages to know more.		See manual pages to learn more.

			tune2fs: create a ext3 journal on a ext2 partition with the -j flag.
			mke2fs: create a ext3 partition with the -j flag.
			debugfs: ext2 and ext3 file system debugger.

	tune2fs: create a ext3 journal on a ext2 partition with the -j flags
	mke2fs: create a ext3 partition with the -j flags
	debugfs: ext2 and ext3 file system debugger

	References		References
	==========		==========

	kernel source: file:/usr/src/linux/fs/ext3		kernel source: <file:fs/ext3/>
	file:/usr/src/linux/fs/jbd		<file:fs/jbd/>

	programs: http://e2fsprogs.sourceforge.net		programs: http://e2fsprogs.sourceforge.net/

	useful link:		useful links: http://www.zip.com.au/~akpm/linux/ext3/ext3-usage.html
	http://www.zip.com.au/~akpm/linux/ext3/ext3-usage.html
	http://www-106.ibm.com/developerworks/linux/library/l-fs7/		http://www-106.ibm.com/developerworks/linux/library/l-fs7/
	http://www-106.ibm.com/developerworks/linux/library/l-fs8/		http://www-106.ibm.com/developerworks/linux/library/l-fs8/