=========================================================
ϡ
linux-3.4.1/Documentation/filesystems/ext4.txt 
Ǥ
Ρ JF ץ < http://www.linux.or.jp/JF/ >
  2012/06/10
  Seiji Kaneko < skaneko at mbn dot or dot jp >
ɼ : Hiroshi Suzuki <setter at reset dot jp>
=========================================================

#Ext4 Filesystem
#===============
Ext4 ե륷ƥ
====================

#Ext4 is an an advanced level of the ext3 filesystem which incorporates
#scalability and reliability enhancements for supporting large filesystems
#(64 bit) in keeping with increasing disk capacities and state-of-the-art
#feature requirements.
ext4 ե륷ƥϡext3 ե륷ƥμοȤơǥ
̤äȼʥե륷ƥ (64bit) 򰷤Τɬפʳĥ
夷ǿεǽ׵˱ΤǤ

#Mailing list:	linux-ext4@vger.kernel.org
᡼󥰥ꥹ:  linux-ext4@vger.kernel.org
#Web site:	http://ext4.wiki.kernel.org
֥:	http://ext4.wiki.kernel.org


#1. Quick usage instructions:
#===========================
1. ñˡ
=================

#Note: More extensive information for getting started with ext4 can be
#      found at the ext4 wiki site at the URL:
#      http://ext4.wiki.kernel.org/index.php/Ext4_Howto
:	ext4 ѤϤäƤΤ˾ܺ٤ϡ URL  ext4
	Wiki Ȥˤޤ
      http://ext4.wiki.kernel.org/index.php/Ext4_Howto

#  - Compile and install the latest version of e2fsprogs (as of this
#    writing version 1.41.3) from:
  - ǿ e2fsprogs (ʸɮǤϥС 1.41.3) ʲ
    ѥ롦󥹥ȡ뤷Ƥ

    http://sourceforge.net/project/showfiles.php?group_id=2406
	
#	or
	ޤ

    ftp://ftp.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/

#	or grab the latest git repository from:
	ޤϰʲǿ git ݥȥꤷƤ

    git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git

#  - Note that it is highly important to install the mke2fs.conf file
#    that comes with the e2fsprogs 1.41.x sources in /etc/mke2fs.conf. If
#    you have edited the /etc/mke2fs.conf file installed on your system,
#    you will need to merge your changes with the version from e2fsprogs
#    1.41.x.
   - e2fsprogs 1.41.x ° mke2fs.conf ե /etc/mke2fs.conf
     ˥󥹥ȡ뤹뤳ȤȤƤפǤƥ˥󥹥ȡ뤷Ƥ
     /etc/mke2fs.conf ե򤹤ǤԽƤϡe2fsprogs 1.41.x
     ǤΤΤ˴¸νޡɬפޤ

#  - Create a new filesystem using the ext4 filesystem type:
   - ext4 ե륷ƥॿפѤƿե륷ƥޤ

    	# mke2fs -t ext4 /dev/hda1

#    Or to configure an existing ext3 filesystem to support extents:
     ޤϡ¸ ext3 ե륷ƥ򡢥ƥȤ򥵥ݡȤ
     ꤷޤ

	# tune2fs -O extents /dev/hda1

#    If the filesystem was created with 128 byte inodes, it can be
#    converted to use 256 byte for greater efficiency via:
    ե륷ƥब 128 Х inode ǺƤϡΨΤ
    256 Х (ޤϤʾ) Ѥ褦ʲΤ褦ѴǤޤ

        # tune2fs -I 256 /dev/hda1

#    (Note: we currently do not have tools to convert an ext4
#    filesystem back to ext3; so please do not do try this on production
#    filesystems.)
     (: ߤΤȤ ext4 ե륷ƥ ext3 ᤹ġ
     Ƥޤ󡣤Τᡢ̳ѤƤե륷ƥǻʤǤ
     )

#  - Mounting:
   - ޥȤ:

	# mount -t ext4 /dev/hda1 /wherever

#  - When comparing performance with other filesystems, it's always
#    important to try multiple workloads; very often a subtle change in a
#    workload parameter can completely change the ranking of which
#    filesystems do well compared to others.  When comparing versus ext3,
#    note that ext4 enables write barriers by default, while ext3 does
#    not enable write barriers by default.  So it is useful to use
#    explicitly specify whether barriers are enabled or not when via the
#    '-o barriers=[0|1]' mount option for both ext3 and ext4 filesystems
#    for a fair comparison.  When tuning ext3 for best benchmark numbers,
#    it is often worthwhile to try changing the data journaling mode; '-o
#    data=writeback' can be faster for some workloads.  (Note however that
#    running mounted with data=writeback can potentially leave stale data
#    exposed in recently written files in case of an unclean shutdown,
#    which could be a security exposure in some situations.)  Configuring
#    the filesystem with a large journal can also be helpful for
#    metadata-intensive workloads.
  - ¾Υե륷ƥȤǽӤκݤϡʣٴĶǻȤ
    פǤɥѥ᡼Τ鷺ѹե륷ƥ¾
    ե륷ƥȤɾŤޤäѤƤޤȤˤ˵
    ޤä ext3 ȤӤξϡext4 饤ȥХꥢɸͭ
    Ƥꡢext3 ɸǤϥ饤ȥХꥢͭˤƤϤʤȤα
    ƤäơʿӤΤˤϥ饤ȥХꥢ̵ͭ
    Ūˡext3  ext4 ե륷ƥȤ '-o barriers=[0|1]' Ȥä
    ꤹΤΩĤǤ礦ext4 ǹΥ٥ޡ̤Ȥʤ褦
    ˥塼˥󥰤硢ǡ㡼ʥ󥰥⡼ɤѹȤˤ
    ͤޤ㤨СΥ٥ޡǤ
    '-o data=writeback' ¾®ȤʤǤ礦 (դȤơ
    data=writeback ⡼ɤǥޥȱѤƤ硢꡼Ǥʤ
    ȥľ˽񤤤ǡߤȤƻĤǽ뤿ᡢˤ
    äƤϥƥ̤Ǥξϳ̤βǽޤ)㡼ʥ礭
    褦ꤹ뤳Ȥ⡢metadata ¿Ѥ٤Ǥǽνˤʤ
    ޤ
    <!-- ext3 Ƚ񤫤ƤΤϤɤƤʤΤǡʸǤϽ -->

#2. Features
#===========
2. ǽ
=======

#2.1 Currently available
2.1 ߻Ȥ뵡ǽ

#* ability to use filesystems > 16TB (e2fsprogs support not available yet)
#* extent format reduces metadata overhead (RAM, IO for access, transactions)
#* extent format more robust in face of on-disk corruption due to magics,
#* internal redundancy in tree
#* improved file allocation (multi-block alloc)
#* lift 32000 subdirectory limit imposed by i_links_count[1]
#* nsec timestamps for mtime, atime, ctime, create time
#* inode version field on disk (NFSv4, Lustre)
#* reduced e2fsck time via uninit_bg feature
#* journal checksumming for robustness, performance
#* persistent file preallocation (e.g for streaming media, databases)
#* ability to pack bitmaps and inode tables into larger virtual groups via the
#  flex_bg feature
#* large file support
#* Inode allocation using large virtual block groups via flex_bg
#* delayed allocation
#* large block (up to pagesize) support
#* efficient new ordered mode in JBD2 and ext4(avoid using buffer head to force
#  the ordering)
* 16TB ĶΥե륷ƥ (e2fsprogs ǤϤޤݡȤƤޤ)
* ᥿ǡХإå (RAM,  I/O, ȥ󥶥) 򸺤餹
  ƥȥեޥå
* magic ˤǥΥǡ˲Фơ趯ʥƥȥե
  ޥå
* ڹ¤Ĺ
* եƤβ (ʣ֥å)
* i_links_count[1] ˤ롢32000 Υ֥ǥ쥯ȥ¤ű
* mtime, atime, ctime, create time()  nsec ñ̤Υॹ
* ǥǤ inode Сե (NFSv4Lustre)
* uninit_bg ǽˤ e2fsck ֤κ︺
* 򤵤ǽ夵뤿Υ㡼ʥåൡǽ
* ³ե (ȥ꡼ߥ󥰥ǥǡ١)
* ӥåȥޥåפ inode ơ֥flex_bg ǽȤä礭ʲۥ롼פ
  ͤൡǽ
* ե륵ݡ
* flex_bg ǽˤ롢礭ʲۥ֥å롼פѤ inode Ƥ
  ǽ
* ٱ
* ֥å (ڡޤ) Υݡ
* JBD2  ext4 ǤθΨŪʿ ordered ⡼ (ݾڤΤ˥Хåեإ
  ɤѤΤ򤱤)

#[1] Filesystems with a block size of 1k may see a limit imposed by the
#directory hash tree having a maximum depth of two.
[1] ֥å 1k Υե륷ƥǤϡǥ쥯ȥϥåĥ꡼
翼 2 Ǥ뤳Ȥ¤󤵤ޤ

#2.2 Candidate features for future inclusion
2.2 ɲø˵󤬤äƤ뵡ǽ

#* Online defrag (patches available but not well tested)
* 饤ǥե饰 (ѥåϤޤʬˤϥƥȤƤޤ)
#* reduced mke2fs time via lazy itable initialization in conjunction with
#  the uninit_bg feature (capability to do this is available in e2fsprogs
#  but a kernel thread to do lazy zeroing of unused inode table blocks
#  after filesystem is first mounted is required for safety)
* itable ٱ uninit_bg ǽȤ߹碌 mke2fs ֤û (
  ¸뵡ǽ e2fsprogs ˤϴȤ߹ޤƤޤե륷ƥ
  κǽΥޥȸ̤ inode ơ֥֥åٱ뤿Υ
  ͥ륹åɤΤɬפǤ)

#There are several others under discussion, whether they all make it in is
#partly a function of how much time everyone has to work on them. Features like
#metadata checksumming have been discussed and planned for a bit but no patches
#exist yet so I'm not sure they're in the near-term roadmap.
ʳˤ⡢ĤεǽȤ߹ߤ˴ؤƵǤη̤Ϥε
ǽǤ줫ɬפʺȻ (θ̤) ˰¸Ǥ礦᥿ǡ
Τ褦ʵǽϵ¿ηײ⤢ޤǤϥѥå
ᤤΥɥޥåפ˸뤫ɤ꤫ǤϤޤ

#The big performance win will come with mballoc, delalloc and flex_bg
#grouping of bitmaps and inode tables.  Some test results available here:
ӥåȥޥåפ inode ơ֥mballocdelalloc ȡflex_bg 롼ԥ
ƳȤˤ礭ǽ¸ߤǤǽ¬̤ΰ
ʲǸƤޤ

 - http://www.bullopensource.org/ext4/20080818-ffsb/ffsb-write-2.6.27-rc1.html
 - http://www.bullopensource.org/ext4/20080818-ffsb/ffsb-readwrite-2.6.27-rc1.html

#3. Options
#==========
3. ޥȥץ
====================

#When mounting an ext4 filesystem, the following option are accepted:
#(*) == default
ext4 ե륷ƥޥȻʲΥץ󤬻Ȥޤ
(*) == 

#ro                   	Mount filesystem read only. Note that ext4 will
#                     	replay the journal (and thus write to the
#                     	partition) even when mounted "read only". The
#                     	mount options "ro,noload" can be used to prevent
#		     	writes to the filesystem.
ro			ե륷ƥ꡼ɥ꡼ǥޥȤ롣ext4
			ϥ꡼ɥ꡼ǥޥȤˤ⥸㡼ʥΥ
			ץ쥤Ԥ (äƥѡƥ˽񤭹ߤԤ)
			ȤդƤޥȥץ
			"ro,noload" ե륷ƥؤν񤭹ߤ˻ߤ
			뤿˻Ѥ뤳ȤǤޤ

#journal_checksum	Enable checksumming of the journal transactions.
#			This will allow the recovery code in e2fsck and the
#			kernel to detect corruption in the kernel.  It is a
#			compatible change and will be ignored by older kernels.
journal_checksum	㡼ʥȥ󥶥˥åͭˤ
			ޤˤ e2fsck ΥꥫХꥳɤͭˤ
			ͥǤ˲򸡽ФǤ褦ˤޤϸ
			äѹǡΥͥǤñ̵뤵
			

#journal_async_commit	Commit block can be written to disk without waiting
#			for descriptor blocks. If enabled older kernels cannot
#			mount the device. This will enable 'journal_checksum'
#			internally.
journal_async_commit	ǥץ֥åν񤭹ߤԤˡߥå
			֥åΥǥؤν񤭹ߤޤͭ
			Ƥ硢ΥͥǤϥǥХޥȤ
			ޤ󡣤ˤꡢŪ journal_checksum 
			ͭˤޤ

#journal_dev=devnum	When the external journal device's major/minor numbers
#			have changed, this option allows the user to specify
#			the new journal location.  The journal device is
#			identified through its new major/minor numbers encoded
#			in devnum.
journal_dev=devnum	㡼ʥǥХ major/minor ֹ椬Ѳ
			硢ΥץȤäƿ㡼ʥΰ֤
			ꤷޤ㡼ʥǥХ devnum ǥ
			ɤ줿 major/minor ֹǻꤵޤ

#norecovery		Don't load the journal on mounting.  Note that
#noload                	if the filesystem was not unmounted cleanly,
#                     	skipping the journal replay will lead to the
#                     	filesystem containing inconsistencies that can
#                     	lead to any number of problems.
norecovery		ޥȻ˥㡼ʥɤޤ󡣤⤷ե
noload			륷ƥब꡼˥ޥȤƤʤä
			ˤϡ㡼ʥץ쥤ФȤˤե
			륷ƥ礬ȯǤ礦η
			꤬͡Ǥ礦

#data=journal		All data are committed into the journal prior to being
#			written into the main file system.  Enabling
#			this mode will disable delayed allocation and
#			O_DIRECT support.
data=journal		ǡϡᥤΥե륷ƥ˽񤭹ˡ
			㡼ʥ˥ߥåȤޤΥ⡼ɤͭ
			硢ٱƤ O_DIRECT ݡȤ̵
			ޤ

#data=ordered	(*)	All data are forced directly out to the main file
#			system prior to its metadata being committed to the
#			journal.
data=ordered	(*)	ǡϡΥ᥿ǡ㡼ʥ˥ߥåȤ
			ˡᥤե륷ƥľܽϤޤ

#data=writeback		Data ordering is not preserved, data may be written
#			into the main file system after its metadata has been
#			committed to the journal.
data=writeback		ǡν¸ޤ󡣥ǡϡΥ᥿ǡ
			㡼ʥ˥ߥåȤ줿Ȥˡᥤե
			ƥ˽񤭹ޤ뤫⤷ޤ

#commit=nrsec	(*)	Ext4 can be told to sync all its data and metadata
#			every 'nrsec' seconds. The default value is 5 seconds.
#			This means that if you lose your power, you will lose
#			as much as the latest 5 seconds of work (your
#			filesystem will not be damaged though, thanks to the
#			journaling).  This default value (or any low value)
#			will hurt performance, but it's good for data-safety.
#			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
#			performance.
commit=nrsec	(*)	Ext4 ϥǡȥ᥿ǡ'nrsec' ƱǤ
			ǥեȤϡ5 äǤϡŸڤƤޤ
			Ǹ 5 ô֤κƤƤޤȤ
			̣ޤ (ե륷ƥϡ㡼ʥ󥰤
			˲ʤǤ礦)
			Υǥե (ޤϡ꾮) ϡǽ˱ƶ
			Ϳޤǡΰϸ夷ޤ0 ˤ
			ϡǥեȤ 5 äˤΤƱ̤Ȥʤޤ
			ȤƤ礭ͤˤȥѥեޥ󥹤夷ޤ

#barrier=<0|1(*)>	This enables/disables the use of write barriers in
#barrier(*)		the jbd code.  barrier=0 disables, barrier=1 enables.
#nobarrier		This also requires an IO stack which can support
#			barriers, and if jbd gets an error on a barrier
#			write, it will disable again with a warning.
#			Write barriers enforce proper on-disk ordering
#			of journal commits, making volatile disk write caches
#			safe to use, at some performance penalty.  If
#			your disks are battery-backed in one way or another,
#			disabling barriers may safely improve performance.
#			The mount options "barrier" and "nobarrier" can
#			also be used to enable or disable barriers, for
#			consistency with other ext4 mount options.
barrier=<0|1(*)>	jbd ɤǤΥ饤ȥХꥢѤͭ/̵ˤޤ
barrier(*)		barrier=0 ̵barrier=1 ͭˤޤ
nobarrier		Υ饤ȥХꥢͭΤˤϥХꥢͭ
			IO åɬפǡ jbd Хꥢ饤Ȼ
			顼ʤзٹȤȤ̵ˤɤޤ
			ȥХꥢ¿ǽεˤꡢŬڤʥǥ
			Υ㡼ʥ륳ߥåȤν¸ȯΥǥ
			饤ȥå˻ѤǤ褦ˤޤ
			⤷ѤƤǥȥ餬ӤǥХå
			åפƤʤɤξˤϡХꥢ̵
			ȤˤǽǤޤ
			ޥȥץ "barrier"  "nobarrier" Х
			̵ͭꤹ뤿Ѥ뤳ȤǤޤ
			Υץϡ¾ ext4 ޥȥץȤΰ
			ݻΤ󶡤Ƥޤ

#inode_readahead_blks=n	This tuning parameter controls the maximum
#			number of inode table blocks that ext4's inode
#			table readahead algorithm will pre-read into
#			the buffer cache.  The default value is 32 blocks.
inode_readahead_blks=n	Υ塼˥󥰥ѥ᡼ϡext4 inode ơ֥
			ߥ르ꥺबХåեåɤߤ롢inode
			ơ֥֥åοκͤ椷ޤͤ 32
			֥åǤ

#nouser_xattr		Disables Extended User Attributes. If you have extended
#			attribute support enabled in the kernel configuration
#			(CONFIG_EXT4_FS_XATTR), extended attribute support
#			is enabled by default on mount. See the attr(5) manual
#			page and http://acl.bestbits.at/ for more information
#			about extended attributes.
nouser_xattr		POSIX ĥ° ̵ˤޤ
			⤷ĥ°ݡȤͥ
			(CONFIG_EXT4_FS_XATTR) ͭˤʤäƤ硢ACL
			ϥޥȻ˥ǥեȤͭˤʤޤ
			POSIX ĥ°ξܺ٤ؤ֤ˤϡattr(5) Υޥ˥奢
			ڡ http://acl.bestbits.at 򸫤Ƥ

#noacl			This option disables POSIX Access Control List
#			support. If ACL support is enabled in the kernel
#			configuration (CONFIG_EXT4_FS_POSIX_ACL), ACL is
#			enabled by default on mount. See the acl(5) manual
#			page and http://acl.bestbits.at/ for more information
#			about acl.
noacl			POSIX ꥹ(POSIX ACL) ݡȤ̵
			ˤޤ⤷ACL ݡȤͥ
			(CONFIG_EXT4_FS_POSIX_ACL) ͭˤʤäƤ硢
			ACL ϥޥȻ˥ǥեȤͭˤʤޤ
			acl ˤĤƤξܺ٤ acl(5) Υޥ˥奢ڡ䡢
			֥ http://acl.bestbits.at/ 򻲾Ȥ

#bsddf		(*)	Make 'df' act like BSD.
#minixdf			Make 'df' act like Minix.
bsddf		(*)	'df' ư BSD Ʊͤˤޤ
minixdf			'df' ư Minix Ʊͤˤޤ

#debug			Extra debugging information is sent to syslog.
debug			ɲåǥХå syslog ޤ

#abort			Simulate the effects of calling ext4_abort() for
#			debugging purposes.  This is normally used while
#			remounting a filesystem which is already mounted.
abort			ǥХåΤ ext4_abort() ƤӽФθ̤򥷥
			졼Ȥޤ̾ϡ˥ޥȤƤ
			ե륷ƥƥޥȤ褦ȤФ
			 (ȯ) ޤ

#errors=remount-ro	Remount the filesystem read-only on an error.
#errors=continue		Keep going on a filesystem error.
#errors=panic		Panic and halt the machine if an error occurs.
#                        (These mount options override the errors behavior
#                        specified in the superblock, which can be configured
#                        using tune2fs)
errors=remount-ro(*)	顼ɤ߹Ѥǥե륷ƥƥޥ
			ޤ
errors=continue		ե륷ƥ२顼ȯƤ³ޤ
errors=panic		顼ȯ顢PANIC ơޥߤޤ
			(Υץϡtune2fs ˻ꤷ
			superblock ǻꤷ顼εư񤭤ޤ)

#data_err=ignore(*)	Just print an error message if an error occurs
#			in a file data buffer in ordered mode.
#data_err=abort		Abort the journal if an error occurs in a file
#			data buffer in ordered mode.
data_err=ignore(*)	ɥ⡼ɤǥեǡХåեǥ顼ȯ
			硢ñ˥顼åϤǤ
data_err=abort		ɥ⡼ɤǥեǡХåեǥ顼ȯ
			硢㡼ʥ۾ｪλޤ

#grpid			Give objects the same group ID as their creator.
#bsdgroups
grpid			֥Ȥκˡǥ쥯ȥƱ
bsdgroups		롼 ID Ϳޤ

#nogrpid	(*)	New objects have the group ID of their creator.
#sysvgroups
nogrpid		(*)	֥Ȥκˡǥ쥯ȥ setgid 
sysvgroups		åȤåȤƤʤ硢ץƱ롼
			ID Ϳޤǥ쥯ȥ setgid ӥåȤ
			ȤƤˤϡǥ쥯ȥΥ롼
			ID Ѥ졢˺줿Τǥ쥯ȥǤ
			äˤ setgid ӥåȤѤޤ

#resgid=n		The group ID which may use the reserved blocks.
resgid=n		ͽ֥åѤƤ褤롼 ID Ǥ

#resuid=n		The user ID which may use the reserved blocks.
resuid=n		ͽ֥åѤƤ褤桼 ID Ǥ

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

#quota			These options are ignored by the filesystem. They
#noquota			are used only by quota tools to recognize volumes
#grpquota		where quota should be turned on. See documentation
#usrquota		in the quota-tools package for more details
#			(http://sourceforge.net/projects/linuxquota).
quota			Υե륷ƥǤϡΥץ̵뤵
noquota			ޤե饰 Quota ͭˤ٤ˡQuota
grpquota		ġǥܥ塼ǧ뤿ˤΤѤޤ
usrquota		ܤ quota-tools ѥåƱʸ򻲾Ȥ
			(http://sourceforge.net/projects/linuxquota).

#jqfmt=<quota type>	These options tell filesystem details about quota
#usrjquota=<file>	so that quota information can be properly updated
#grpjquota=<file>	during journal replay. They replace the above
#			quota options. See documentation in the quota-tools
#			package for more details
#			(http://sourceforge.net/projects/linuxquota).
jqfmt=<quota type>	Υץϥ㡼ʥץ쥤 Quota 
usrjquota=<file>	褦ե륷ƥ Quota ξ
grpjquota=<file>	٤ꤹ뤿ΤΤǤϾ嵭 quota 
			֤ޤ
			ܤ quota-tools ѥåƱʸ򻲾Ȥ
			(http://sourceforge.net/projects/linuxquota).

#stripe=n		Number of filesystem blocks that mballoc will try
#			to use for allocation size and alignment. For RAID5/6
#			systems this should be the number of data
#			disks *  RAID chunk size in file system blocks.
stripe=n		mballoc ñ̤ȥ饤˻Ѥ褦
			ե륷ƥ֥åǤRAID5/6 Ǥϡ
			ͤϥǡǥȡե륷ƥ֥å
			RAID 󥯥ȤѤˤ٤Ǥ
			
#delalloc	(*)	Defer block allocation until just before ext4
#			writes out the block(s) in question.  This
#			allows ext4 to better allocation decisions
#			more efficiently.
#nodelalloc		Disable delayed allocation.  Blocks are allocated
#			when the data is copied from userspace to the
#			page cache, either via the write(2) system call
#			or when an mmap'ed page which was previously
#			unallocated is written for the first time.
delalloc	(*)	ext4 оݥ֥å񤭹ľޤǥ֥å
			Ƥٱ䤵ޤˤꡢext4 γȽǤ
			ĸΨޤ
nodelalloc		ٱƤ̵ˤޤwrite(2) ƥॳ롢
			ޤ̤Ƥä mmap Ƥڡǽ
			񤭹ޤ뤳Ȥˤäơǡ桼ڡ
			å˽񤭹ޤ줿ǥ֥åƤԤ
			ޤ

#max_batch_time=usec	Maximum amount of time ext4 should wait for
#			additional filesystem operations to be batch
#			together with a synchronous write operation.
#			Since a synchronous write operation is going to
#			force a commit and then a wait for the I/O
#			complete, it doesn't cost much, and can be a
#			huge throughput win, we wait for a small amount
#			of time to see if any other transactions can
#			piggyback on the synchronous write.   The
#			algorithm used is designed to automatically tune
#			for the speed of the disk, by measuring the
#			amount of time (on average) that it takes to
#			finish committing a transaction.  Call this time
#			the "commit time".  If the time that the
#			transaction has been running is less than the
#			commit time, ext4 will try sleeping for the
#			commit time to see if other operations will join
#			the transaction.   The commit time is capped by
#			the max_batch_time, which defaults to 15000us
#			(15ms).   This optimization can be turned off
#			entirely by setting max_batch_time to 0.
max_batch_time=usec	ext4 Ʊ񤭹ˡ̤Υե碌
			Хå뤿ԤĻ֤κͤꤷޤƱ
			߽϶ŪʥߥåȤԤθ I/O δλ
			ԤĤᡢƱ񤭹ߤȰˤǤ¾Υȥ󥶥
			̵ͭûԤĤȤϡȤ롼ץ
			̤礭ʲˤʤޤǻȤƤ륢르
			ϡǥΥȥ󥶥Υߥåȴλפ
			 (ʿѻ) ¬ꤹ뤳Ȥˤꡢǥ®٤
			Ŭ褦߷פ줿ΤǤǾ嵭Ρ֥ߥ
			ȴλפ֡פ Commit time" ȸƤ֤Ȥˤ
			⤷ȥ󥶥¹ԤƤ֤ Commit
			time 꾮ʤСext4  Commit time ꡼
			פ¾νȥ󥶥˹ήǤ뤫ɤ
			Ĵ٤ޤ Commit time  max_batch_time ˤ
			¤ꤵޤmax_batch_time ɸͤ
			15000us (15ms) Ǥmax_batch_time  0 Ȼꤹ
			ȤǡκŬ̵Ǥޤ

#min_batch_time=usec	This parameter sets the commit time (as
#			described above) to be at least min_batch_time.
#			It defaults to zero microseconds.  Increasing
#			this parameter may improve the throughput of
#			multi-threaded, synchronous workloads on very
#			fast disks, at the cost of increasing latency.
min_batch_time=usec	Υѥ᡼ commit time (嵭) ʤȤ
			min_batch_time ʾǤ뤳Ȥꤷޤɸͤ 0
			ms ǤΥѥ᡼䤷硢ޥåɤ
			ƱȤ٤®ʥǥǼ¹ԤƤ硢
			ƥ󥷥äΥȤ˥롼ץåȤޤ

#journal_ioprio=prio	The I/O priority (from 0 to 7, where 0 is the
#			highest priority) which should be used for I/O
#			operations submitted by kjournald2 during a
#			commit operation.  This defaults to 3, which is
#			a slightly higher priority than the default I/O
#			priority.
journal_ioprio=prio	kjournald2 ߥåȽȯԤ I/O Ѥ
			 I/O ץ饤ƥ (0  7 ǡ0 ǹΥץ饤
			ƥǤ) ꤷޤɸͤ 3 ǡ̾
			I/O ץ饤ƥ꾯⤯ʤäƤޤ

#auto_da_alloc(*)	Many broken applications don't use fsync() when
#noauto_da_alloc		replacing existing files via patterns such as
#			fd = open("foo.new")/write(fd,..)/close(fd)/
#			rename("foo.new", "foo"), or worse yet,
#			fd = open("foo", O_TRUNC)/write(fd,..)/close(fd).
#			If auto_da_alloc is enabled, ext4 will detect
#			the replace-via-rename and replace-via-truncate
#			patterns and force that any delayed allocation
#			blocks are allocated such that at the next
#			journal commit, in the default data=ordered
#			mode, the data blocks of the new file are forced
#			to disk before the rename() operation is
#			committed.  This provides roughly the same level
#			of guarantees as ext3, and avoids the
#			"zero-length" problem that can happen when a
#			system crashes before the delayed allocation
#			blocks are forced to disk.
auto_da_alloc(*)	¿β줿ץꥱϡfd = open("foo.new")/
noauto_da_alloc		write(fd,..)/close(fd)/rename("foo.new", "foo") 
			ɤΥѥ󡢤뤤Ϥٰ
			fd = open("foo", O_TRUNC)/write(fd,..)/close(fd)
			ѥǡfsync() ȤʤǴ¸Υե
			ؤޤauto_da_alloc ͭʾ硢ext4 ϤΥ
			͡ˤեؤ truncate ˤե
			ؤΥѥΤɸΥǡ
			ɥ⡼ɤξˡ͡ߥåȤ˿
			եΥǡ֥åǥ˽񤭹ޤ褦
			ٱƤ줿֥å򼡤Υ㡼ʥ륳ߥåȻ
			Ū˳ƤޤνǤۤ ext3 Ʊ٤
			ڤǤٱƤ줿֥åǥ˽񤫤
			˥ƥबå夷ΡĹ 0 ˤʤ
			 (Ʊ٤) Ǥޤ

#noinit_itable		Do not initialize any uninitialized inode table
#			blocks in the background.  This feature may be
#			used by installation CD's so that the install
#			process can complete as quickly as possible; the
#			inode table initialization process would then be
#			deferred until the next time the  file system
#			is unmounted.
noinit_itable		Ƥʤ inode ơ֥Хå饦
			ǽޤ󡣤εǽϡ󥹥ȡ CD 
			ǽʸ¤®󥹥ȡλǤ褦ˤ
			Ѥ뤳ȤǤޤinode ơ֥ν
			˥ե륷ƥब unmount ޤǱޤ

#init_itable=n		The lazy itable init code will wait n times the
#			number of milliseconds it took to zero out the
#			previous block group's inode table.  This
#			minimizes the impact on the system performance
#			while file system's inode table is being initialized.
init_itable=n		itable ٱɤϡ inode ơ֥֥
			å 0 ꥢ塢n ߥԤäƼν¹Ԥ
			ϥե륷ƥ inode ơ֥ν
			ƥǽͿƶǾ¤ޤޤ

#discard		Controls whether ext4 should issue discard/TRIM
#nodiscard(*)		commands to the underlying block device when
#			blocks are freed.  This is useful for SSD devices
#			and sparse/thinly-provisioned LUNs, but it is off
#			by default until sufficient testing has been done.
discard			ext4  discard/TRIM ޥɤȯԤ뤫ݤ
nodiscard(*)		ޤΥޥɤϥ֥å˲̤ΥǥХ
			ФȯԤޤ SSD ǥХ䡢ѡ
			ޤϥץӥ˥󥰤Ѥ LUN Ω
			ޤ߽ʬʥƥȤʤƤʤΤǡɸ
			 off ˤʤäƤޤ

#nouid32			Disables 32-bit UIDs and GIDs.  This is for
#			interoperability  with  older kernels which only
#			store and expect 16-bit values.
nouid32			32-bit UID  GID Ȥʤ褦ˤޤϡ
			16 bit ͤΤߤ񤭹ߡѤŤͥȤθ
			ΤΤΤǤ

#block_validity		This options allows to enables/disables the in-kernel
#noblock_validity	facility for tracking filesystem metadata blocks
#			within internal data structures. This allows multi-
#			block allocator and other routines to quickly locate
#			extents which might overlap with filesystem metadata
#			blocks. This option is intended for debugging
#			purposes and since it negatively affects the
#			performance, it is off by default.
block_validity		Υץϡͥǡ¤Ȥ
noblock_validity	ޤ줿᥿ǡ֥å׵ǽͭ/̵
			ΤǤ׵ǽϡʣ֥åΥ
			ʤɤνǥե륷ƥ᥿ǡ֥å
			ȽŤʤǽΤΰˤ륨ƥȤ᤯
			Ĥ뤿ΤΤǤ
			ΥץϥǥХåѤŪΤΤǡǽ
			αƶͿޤɸǤϥդˤʤäƤޤ

#dioread_lock		Controls whether or not ext4 should use the DIO read
#dioread_nolock		locking. If the dioread_nolock option is specified
#			ext4 will allocate uninitialized extent before buffer
#			write and convert the extent to initialized after IO
#			completes. This approach allows ext4 code to avoid
#			using inode mutex, which improves scalability on high
#			speed storages. However this does not work with
#			data journaling and dioread_nolock option will be
#			ignored with kernel warning. Note that dioread_nolock
#			code path is only used for extent-based files.
#			Because of the restrictions this options comprises
#			it is off by default (e.g. dioread_lock).
dioread_lock		ext4  DIO ꡼ɥåȤɤ椷ޤ
dioread_nolock		⤷ dioread_nolock ץ󤬻ꤵƤ
			ϡext4 ϥХåե饤̤֤Υ
			ȤơIO λ˥ƥȤ
			ѹޤμˤꡢext4  inode mutex
			ȤʤǺѤ褦ˤʤ뤿ᡢ®ʥȥ졼
			ȤäΥƥγĥ夷ޤ
			εǽϥǡ㡼ʥ󥰤ȶˤϻȤǡ
			㡼ʥ󥰤ͭʾˤ dioread_nolock 
			ץϥͥٹåФ̵뤵
			Ȥˤʤޤ dioread_nolock ɽϥ
			ƥȥ١ΥեǤΤѤ뤳Ȥα
			դΥץȼΤᡢɸ
			ϥ (Ĥޤ dioread_lock ⡼) ˤʤäƤޤ
#i_version		Enable 64-bit inode version support. This option is
#			off by default.
i_version		64-bit inode СΥݡȤͭˤޤ
			ΥץϡɸǤϥդˤʤäƤޤ

#Data Mode
#=========
ǡ⡼
===========
#There are 3 different data modes:
3 Ĥΰۤʤǡ⡼ɤ󶡤Ƥޤ

#* writeback mode
#In data=writeback mode, ext4 does not journal data at all.  This mode provides
#a similar level of journaling as that of XFS, JFS, and ReiserFS in its default
#mode - metadata journaling.  A crash+recovery can cause incorrect data to
#appear in files which were written shortly before the crash.  This mode will
#typically provide the best ext4 performance.
* 饤ȥХå⡼ (writeback mode)
data=writeback ⡼ɤΤȤext4 ϥǡ㡼ʥ뤷ޤ
ϡXFS, JFS, ReiserFS Υǥեȥ⡼ (᥿ǡ㡼ʥ) 
Ʊ٥Υ㡼ʥ󥰤󶡤ޤ
å + ꥫХ ǡåľ˽񤭹ޤ줿եǡ
뤫⤷ޤ̾盧Υ⡼ɤˤǹ ext4 ѥեޥ󥹤
ޤ

#* ordered mode
#In data=ordered mode, ext4 only officially journals metadata, but it logically
#groups metadata information related to data changes with the data blocks into a
#single unit called a transaction.  When it's time to write the new metadata
#out to disk, the associated data blocks are written first.  In general,
#this mode performs slightly slower than writeback but significantly faster
#than journal mode.
* ɥ⡼ (ordered mode)
data=ordered ⡼ɤΤȤext4 ϸˤϥ᥿ǡΤߤ򥸥㡼ʥ뤷ޤ
κݤ˥᥿ǡȥǡ֥åϥȥ󥶥ȸƤФ 1 Ĥñ
̤ˡŪˤޤȤƤޤǥ˿᥿ǡ񤭹
顢Ϣǡ֥å˽񤭹ޤޤŪˡΥ⡼ɤϡ
ȥХå¿٤ưȤʤޤ㡼ʥ⡼ɤϤʤ®
ޤ

#* journal mode
#data=journal mode provides full data and metadata journaling.  All new data is
#written to the journal first, and then to its final location.
#In the event of a crash, the journal can be replayed, bringing both data and
#metadata into a consistent state.  This mode is the slowest except when data
#needs to be read from and written to disk at the same time where it
#outperforms all others modes.  Enabling this mode will disable delayed
#allocation and O_DIRECT support.
* 㡼ʥ⡼ (journal mode)
data=journal ⡼ɤϡǡȥ᥿ǡδʥ㡼ʥ󥰤ޤ
٤Ƥοǡϡ˥㡼ʥ˽񤭹ޤ졢θ˽ΰ֤ؽ
ޤޤåκݡ㡼ʥϥץ쥤졢ǡȥ᥿ǡ
ξ̷̵֤˲ޤΥ⡼ɤ̾ϤäȤ٤Τ
ǥؤΥǡɤߤȽ񤭹ߤƱ˹Ԥɬפϡ¾
Υ⡼ɤǽǤΥ⡼ɤͭˤ硢ٱ䥢
O_DIRECT ݡȤ̵ˤʤޤ


#/proc entries
#=============
/proc ȥ
==============

#Information about mounted ext4 file systems can be found in
#/proc/fs/ext4.  Each mounted filesystem will have a directory in
#/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
#/proc/fs/ext4/dm-0).   The files in each per-device directory are shown
#in table below.
ޥȤƤ ext4 ե륷ƥξ /proc/fs/ext4 
ޤޥȤƤե륷ƥγơбǥХ̾
ˤ̾ΤΥǥ쥯ȥ꤬ /proc/fs/ext4 ʲ˺ޤ (㤨
/proc/fs/ext4/hdc  /proc/fs/ext4/dm-0)ƥǥХȤΥǥ쥯ȥ
եϰʲΥơ֥ΤȤǤ

#Files in /proc/fs/ext4/<devname>
/proc/fs/ext4/<devname> Υե
..............................................................................
# File            Content
# mb_groups       details of multiblock allocator buddy cache of free blocks
 ե	  
 mb_groups	  ե꡼֥å buddy åΥޥ֥å
 		  ξܺپ
..............................................................................

#/sys entries
#============
/sys ȥ
=============

#Information about mounted ext4 file systems can be found in
#/sys/fs/ext4.  Each mounted filesystem will have a directory in
#/sys/fs/ext4 based on its device name (i.e., /sys/fs/ext4/hdc or
#/sys/fs/ext4/dm-0).   The files in each per-device directory are shown
#in table below.
ޥȤ줿 ext4 ե륷ƥξ /sys/fs/ext4 Ǥޤ
ޥȤƤե륷ƥγơбơǥХ̾򸵤ˤ̾
ΤΥǥ쥯ȥ꤬ /sys/fs/ext4 ʲ˺ޤ (㤨
/sys/fs/ext4/hdc  /sys/fs/ext4/dm-0)ƥǥХȤΥǥ쥯ȥ
եϰʲΥơ֥ΤȤǤ


#Files in /sys/fs/ext4/<devname>
#(see also Documentation/ABI/testing/sysfs-fs-ext4)
/sys/fs/ext4/<devname> Υե
 (Documentation/ABI/testing/sysfs-fs-ext4 ⸫Ƥ)
..............................................................................
# File                         Content
 ե		      

# delayed_allocation_blocks    This file is read-only and shows the number of
#                              blocks that are dirty in the page cache, but
#                              which do not have their location in the
#                              filesystem allocated yet.
 delayed_allocation_blocks    Υեϥ꡼ɥ꡼ǡڡ
 			      Υƥǡĥե륷ƥ
 			      ޤΰ褬ƤƤʤڡο
 			      ޤ

# inode_goal                   Tuning parameter which (if non-zero) controls
#                              the goal inode used by the inode allocator in
#                              preference to all other allocation heuristics.
#                              This is intended for debugging use only, and
#                              should be 0 on production systems.
 inode_goal		      塼˥󥰥ѥ᡼Ǥꡢinode 
 			      Ѥ goal inode εư¾Υ
 			      άͥ褷 (0 ʳξ) 椹
 			      ΤΤǤ
 			      ϥǥХåΤߤѤ뤳ȤտޤƤ
 			      ꡢ̾ﱿѻ 0 ˤƤ٤Ǥ

# inode_readahead_blks         Tuning parameter which controls the maximum
#                              number of inode table blocks that ext4's inode
#                              table readahead algorithm will pre-read into
#                              the buffer cache
 inode_readahead_blks	      塼˥󥰥ѥ᡼Ǥꡢext4  inode
 			      ơ֥ɤߥ르ꥺबХåեå
 			      ɤߤ inode ơ֥Υ֥å
 			      ꤷޤ

# lifetime_write_kbytes        This file is read-only and shows the number of
#                              kilobytes of data that have been written to this
#                              filesystem since it was created.
 lifetime_write_kbytes	      Υեϥ꡼ɥ꡼ǡƤ
 			      ʹߤΥե륷ƥ˽񤭤ޤ줿ǡ
 			      Хñ̤Ǽޤ

# max_writeback_mb_bump        The maximum number of megabytes the writeback
#                              code will try to write out before move on to
#                              another inode.
 max_writeback_mb_bump	      饤ȥХåɤ inode ˿ʤ˽
 			      ߤߤ륵κͤᥬХñ
 			      ǻꤷޤ

# mb_group_prealloc            The multiblock allocator will round up allocation
#                              requests to a multiple of this tuning parameter if
#                              the stripe size is not set in the ext4 superblock
 mb_group_prealloc	      ޥ֥åϡext4 ѡ
 			      å˥ȥ饤ץꤵƤʤ
 			      硢׵򤳤Υ塼˥󥰥
 			      ᡼ܤڤ夲ޤ

# mb_max_to_scan               The maximum number of extents the multiblock
#                              allocator will search to find the best extent
 mb_max_to_scan		      ޥ֥åŬʥƥ
 			      õݤõ륨ƥȤκͤ
 			      ޤ

# mb_min_to_scan               The minimum number of extents the multiblock
#                              allocator will search to find the best extent
 mb_min_to_scan		      ޥ֥åŬʥƥ
 			      õݤõ륨ƥȤκǾͤ
 			      ޤ

# mb_order2_req                Tuning parameter which controls the minimum size
#                              for requests (as a power of 2) where the buddy
#                              cache is used
 mb_order2_req		      buddy åѻ˥ꥯȤκǾ
 			       2 Τ٤ǻꤹ塼˥󥰥ѥ᡼
 			      Ǥ

# mb_stats                     Controls whether the multiblock allocator should
#                              collect statistics, which are shown during the
#                              unmount. 1 means to collect statistics, 0 means
#                              not to collect statistics
 mb_stats		      ޥ֥å unmount ɽ
 			      뤿׾򽸤뤫ݤ椷ޤ
 			      1 ׾򽸤뤳Ȥ0 Ͻʤ
 			      ̣ޤ

# mb_stream_req                Files which have fewer blocks than this tunable
#                              parameter will have their blocks allocated out
#                              of a block group specific preallocation pool, so
#                              that small files are packed closely together.
#                              Each large file will have its blocks allocated
#                              out of its own unique preallocation pool.
 mb_stream_req		      ϥ塼˥󥰥ѥ᡼ǤꡢΥѥ
 			      ᡼ʲΥ֥åγƤξˤϡ
 			      ֥å롼̤λƥס뤫
 			      åƤ褦ˤե뤬
 			      ᤯˥ѥåƽ褦ˤޤ
 			      礭ʥեϡ礭ʥեѤλ
 			      ƥס뤫֥åƤޤ

# session_write_kbytes         This file is read-only and shows the number of
#                              kilobytes of data that have been written to this
#                              filesystem since it was mounted.
 session_write_kbytes	      Υեϥ꡼ɥ꡼ǡޥȤ
 			      Ƥե륷ƥ˽񤭤ޤ줿ǡ
 			      Хñ̤Ǽޤ
..............................................................................

Ioctls
======

#There is some Ext4 specific functionality which can be accessed by applications
#through the system call interfaces. The list of all Ext4 specific ioctls are
#shown in the table below.
ƥॳ륤󥿡եˤꥢץꥱ󤫤饢ǽ ext4
ͭεǽĤޤext4 ͭ ioctl ΰʲɽ˼ޤ

#Table of Ext4 specific ioctls
ext4 ͭ ioctl ɽ
..............................................................................
# Ioctl			      Description
 Ioctl			     
# EXT4_IOC_GETFLAGS	      Get additional attributes associated with inode.
#			      The ioctl argument is an integer bitfield, with
#			      bit values described in ext4.h. This ioctl is an
#			      alias for FS_IOC_GETFLAGS.
 EXT4_IOC_GETFLAGS	     inode ˴طɲåȥӥ塼Ȥޤ
 			      ioctl ΰϥӥåȥեɤǡ bit
 			     ΰ̣ ext4.h ˵ܤƤޤ ioctl
 			      FS_IOC_GETFLAG ̾ˤʤޤ

# EXT4_IOC_SETFLAGS	      Set additional attributes associated with inode.
#			      The ioctl argument is an integer bitfield, with
#			      bit values described in ext4.h. This ioctl is an
#			      alias for FS_IOC_SETFLAGS.
 EXT4_IOC_SETFLAGS	     inode ˴طɲåȥӥ塼Ȥꤷޤ
 			      ioctl ΰϥӥåȥեɤǡ bit
 			     ΰ̣ ext4.h ˵ܤƤޤ ioctl
 			      FS_IOC_SETFLAG ̾ˤʤޤ

 EXT4_IOC_GETVERSION
 EXT4_IOC_GETVERSION_OLD
#			      Get the inode i_generation number stored for
#			      each inode. The i_generation number is normally
#			      changed only when new inode is created and it is
#			      particularly useful for network filesystems. The
#			      '_OLD' version of this ioctl is an alias for
#			      FS_IOC_GETVERSION.
			      inode ˳ǼƤ inode 
			     i_generation ֹޤi_generation
			     ֹ̾￷ inode ˤΤ
			     ѹ졢ͥåȥե륷ƥäͭѤǤ
			     _OLD դǤ ioctl  FS_IOC_GETVERSION 
			     ̾Ǥ

 EXT4_IOC_SETVERSION
 EXT4_IOC_SETVERSION_OLD
#			      Set the inode i_generation number stored for
#			      each inode. The '_OLD' version of this ioctl
#			      is an alias for FS_IOC_SETVERSION.
			      inode ˳ǼƤ inode 
			     i_generation ֹꤷޤ
			     _OLD դǤ ioctl  FS_IOC_SETVERSION 
			     ̾Ǥ

# EXT4_IOC_GROUP_EXTEND	      This ioctl has the same purpose as the resize
#			      mount option. It allows to resize filesystem
#			      to the end of the last existing block group,
#			      further resize has to be done with resize2fs,
#			      either online, or offline. The argument points
#			      to the unsigned logn number representing the
#			      filesystem new block count.
 EXT4_IOC_GROUP_EXTEND	      ioctl  resize mount ץƱ
 			     ŪޤˤꡢǽλѺѤߤΥ
 			     å롼פؤΥꥵǽˤʤޤ
 			     ʾΥꥵϡresize2fsѤƹԤɬ
 			     פޤϥե륷ƥο
 			     ֥å򼨤̵ long ؤޤ

# EXT4_IOC_MOVE_EXT	      Move the block extents from orig_fd (the one
#			      this ioctl is pointing to) to the donor_fd (the
#			      one specified in move_extent structure passed
#			      as an argument to this ioctl). Then, exchange
#			      inode metadata between orig_fd and donor_fd.
#			      This is especially useful for online
#			      defragmentation, because the allocator has the
#			      opportunity to allocate moved blocks better,
#			      ideally into one contiguous extent.
 EXT4_IOC_MOVE_EXT	     orig_fd (ioctl λؤ) Υ֥å
 			     Ȥ doner_fd (ioctl ؤΰȤͿ
 			      move_extent ¤Τǻꤵ줿) ˰ư
 			     orig_fd  doner_fd  inode ᥿ǡ
 			     򴹤ޤεǽϡư֥åγ
 			     ƤǤ (㤨ФҤȤĤܤ륨
 			     ƥȤ˳ƤŪǤ) ǽ
 			     뤿ᡢä˥饤ǥե饰Ǥ

# EXT4_IOC_GROUP_ADD	      Add a new group descriptor to an existing or
#			      new group descriptor block. The new group
#			      descriptor is described by ext4_new_group_input
#			      structure, which is passed as an argument to
#			      this ioctl. This is especially useful in
#			      conjunction with EXT4_IOC_GROUP_EXTEND,
#			      which allows online resize of the filesystem
#			      to the end of the last existing block group.
#			      Those two ioctls combined is used in userspace
#			      online resize tool (e.g. resize2fs).
 EXT4_IOC_GROUP_ADD	     ¸ޤϿΥ롼ץǥץ֥å
 			     ˿롼ץǥץɲäޤ
 			     롼ץǥץϡ ioctl ΰ
 			     ȤϤ ext4_new_group_input ¤Τ
 			     ܤޤ
 			     εǽϺǽλѺѤߤΥ֥å롼פؤ
 			     ե륷ƥΥ饤ꥵԤ
 			     EXT4_IOC_GROUP_EXTEND ǽȤ߹碌ƻȤ
 			     Ǥ 2 Ĥ ioctl ϥ桼֥
 			     ꥵġ (Ĥޤ resize2fs) Ȥ߹
 			     碌ƻȤƤޤ

# EXT4_IOC_MIGRATE	      This ioctl operates on the filesystem itself.
#			      It converts (migrates) ext3 indirect block mapped
#			      inode to ext4 extent mapped inode by walking
#			      through indirect block mapping of the original
#			      inode and converting contiguous block ranges
#			      into ext4 extents of the temporary inode. Then,
#			      inodes are swapped. This ioctl might help, when
#			      migrating from ext3 to ext4 filesystem, however
#			      suggestion is to create fresh ext4 filesystem
#			      and copy data from the backup. Note, that
#			      filesystem has to support extents for this ioctl
#			      to work.
 EXT4_IOC_MIGRATE	      ioctl ϥե륷ƥ༫Τޤ
 			     ϡext3 δܥ֥åޥåפ줿 inode
 			      ext4 Υƥȥޥåפ줿 inode ˡ
 			      inode δܥ֥åޥåפ귫ä
 			     ֥åϰϤѴƹ˰ inode  ext4
 			     ƥȤѴΤ inode 򴹤
 			     ȤˤѴưܹԤޤεǽ ext3
 			      ext4 ե륷ƥؤΰܹԻѲǽ
 			     Ǥext4 ե륷ƥ򿷵˺äƤ
 			     ˥Хååפǡ򥳥ԡ
 			     ɤǤ ioctl ưΤˤϥ
 			     륷ƥबƥȤ򥵥ݡȤƤ
 			     ɬפ뤳Ȥαդ

# EXT4_IOC_ALLOC_DA_BLKS      Force all of the delay allocated blocks to be
#			      allocated to preserve application-expected ext3
#			      behaviour. Note that this will also start
#			      triggering a write of the data blocks, but this
#			      behaviour may change in the future as it is
#			      not necessary and has been done this way only
#			      for sake of simplicity.
 EXT4_IOC_ALLOC_DA_BLKS	     ٱоݤΥ֥åŪƳ
 			     Ƥ뤳Ȥˤꡢץꥱ󤫤鸫 ext3
 			     εưƱˤʤ褦ˤޤεǽˤ
 			     ߤμǤϥǡ֥åν񤭹ߤϤޤ
 			     ȤդƤο񤤤
 			     ɬפʤΤǤϤʤñ㲽Τˤʤ
 			     ΤǤ뤿ᡢѹǽϤ
 			     ޤ

# EXT4_IOC_RESIZE_FS	      Resize the filesystem to a new size.  The number
#			      of blocks of resized filesystem is passed in via
#			      64 bit integer argument.  The kernel allocates
#			      bitmaps and inode table, the userspace tool thus
#			      just passes the new number of blocks.
 EXT4_IOC_RESIZE_FS	      ե륷ƥ򿷤˥ꥵ
 			      ꥵΥե륷ƥΥ֥å
 			       64-bit ͤΰȤϤޤ
 			      ͥ뤬ӥåȥޥåפ inode ơ֥
 			      뤿ᡢ桼֤ΥġϿ֥å
 			      ñϤǤ
..............................................................................

#References
#==========
ͻ
========

#kernel source:	<file:fs/ext4/>
#		<file:fs/jbd2/>
ͥ륽:	<file:fs/ext4/>
		<file:fs/jbd2/>

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

#useful links:	http://fedoraproject.org/wiki/ext3-devel
#		http://www.bullopensource.org/ext4/
#		http://ext4.wiki.kernel.org/index.php/Main_Page
#		http://fedoraproject.org/wiki/Features/Ext4
Ωĥ:	http://fedoraproject.org/wiki/ext3-devel
		http://www.bullopensource.org/ext4/
		http://ext4.wiki.kernel.org/index.php/Main_Page
		http://fedoraproject.org/wiki/Features/Ext4

