X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=misc%2Fmke2fs.8.in;h=c0b5324569a186bafe6e6d39f04a2e73c3c194d2;hb=b575249eb334e3f95319eea68c9606f43db05a07;hp=bfd421e9b4eb4dcf0c5cfbf490e553e324b95173;hpb=b71508075780cfb31258c006a2c6bf08b061d421;p=tools%2Fe2fsprogs.git

diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in
index bfd421e..c0b5324 100644
--- a/misc/mke2fs.8.in
+++ b/misc/mke2fs.8.in
@@ -4,7 +4,7 @@
 .\"
 .TH MKE2FS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
 .SH NAME
-mke2fs \- create an ext2/ext3/ext4 filesystem
+mke2fs \- create an ext2/ext3/ext4 file system
 .SH SYNOPSIS
 .B mke2fs
 [
@@ -18,8 +18,15 @@ mke2fs \- create an ext2/ext3/ext4 filesystem
 .I block-size
 ]
 [
-.B \-f
-.I fragment-size
+.B \-C
+.I cluster-size
+]
+[
+.B \-d
+.I root-directory
+]
+[
+.B \-D
 ]
 [
 .B \-g
@@ -61,7 +68,7 @@ mke2fs \- create an ext2/ext3/ext4 filesystem
 ]
 [
 .B \-O
-.IR feature [,...]
+[^]\fIfeature\fR[,...]
 ]
 [
 .B \-q
@@ -106,9 +113,17 @@ mke2fs \- create an ext2/ext3/ext4 filesystem
 [
 .B \-V
 ]
+[
+.B \-e
+.I errors-behavior
+]
+[
+.B \-z
+.I undo_file
+]
 .I device
 [
-.I blocks-count
+.I fs-size
 ]
 @JDEV@.sp
 @JDEV@.B "mke2fs \-O journal_dev"
@@ -136,25 +151,54 @@ mke2fs \- create an ext2/ext3/ext4 filesystem
 @JDEV@]
 @JDEV@.I external-journal
 @JDEV@[
-@JDEV@.I blocks-count
+@JDEV@.I fs-size
 @JDEV@]
 .SH DESCRIPTION
 .B mke2fs
-is used to create an ext2, ext3, or ext4 filesystem, usually in a disk
-partition.
-.I device
-is the special file corresponding to the device (e.g
-.IR /dev/hdXX ).
-.I blocks-count
-is the number of blocks on the device.  If omitted,
+is used to create an ext2, ext3, or ext4 file system, usually in a disk
+partition (or file) named by
+.IR device .
+.PP
+The file system size is specified by
+.IR fs-size .
+If
+.I fs-size
+does not have a suffix, it is interpreted as power-of-two kilobytes,
+unless the
+.B \-b
+.I blocksize
+option is specified, in which case
+.I fs-size
+is interpreted as the number of
+.I blocksize
+blocks.   If the fs-size is suffixed by 'k', 'm', 'g', 't'
+(either upper-case or lower-case), then it is interpreted in
+power-of-two kilobytes, megabytes, gigabytes, terabytes, etc.
+If
+.I fs-size
+is omitted,
+.B mke2fs
+will create the file system based on the device size.
+.PP
+If
 .B mke2fs
-automagically figures the file system size.  If called as
+is run as
+.B mkfs.XXX
+(i.e.,
+.BR mkfs.ext2 ,
+.BR mkfs.ext3 ,
+or
+.BR mkfs.ext4 )
+the option
+.B \-t
+.I XXX
+is implied; so
 .B mkfs.ext3
-a journal is created as if the
-.B \-j
-option was specified.
+will create a file system for use with ext3,
+.B mkfs.ext4
+will create a file system for use with ext4, and so on.
 .PP
-The defaults of the parameters for the newly created filesystem, if not
+The defaults of the parameters for the newly created file system, if not
 overridden by the options listed below, are controlled by the
 .B /etc/mke2fs.conf
 configuration file.  See the
@@ -163,12 +207,14 @@ manual page for more details.
 .SH OPTIONS
 .TP
 .BI \-b " block-size"
-Specify the size of blocks in bytes.  Valid block-size values are 1024,
-2048 and 4096 bytes per block.  If omitted,
-block-size is heuristically determined by the filesystem size and
-the expected usage of the filesystem (see the
+Specify the size of blocks in bytes.  Valid block-size values are powers of two
+from 1024 up to 65536 (however note that the kernel is able to mount only
+file systems with block-size smaller or equal to the system page size - 4k on
+x86 systems, up to 64k on ppc64 or aarch64 depending on kernel configuration).
+If omitted, block-size is heuristically determined by the file system size and
+the expected usage of the file system (see the
 .B \-T
-option).  If
+option).  In most common cases, the default block size is 4k. If
 .I block-size
 is preceded by a negative sign ('-'), then
 .B mke2fs
@@ -184,8 +230,46 @@ Check the device for bad blocks before creating the file system.  If
 this option is specified twice, then a slower read-write
 test is used instead of a fast read-only test.
 .TP
+.B \-C " cluster-size"
+Specify the size of cluster in bytes for file systems using the bigalloc
+feature.  Valid cluster-size values are from 2048 to 256M bytes per
+cluster.  This can only be specified if the bigalloc feature is
+enabled.  (See the
+.B ext4 (5)
+man page for more details about bigalloc.)   The default cluster size if
+bigalloc is enabled is 16 times the block size.
+.TP
+.BI \-d " root-directory"
+Copy the contents of the given directory into the root directory of the
+file system.
+.TP
+.B \-D
+Use direct I/O when writing to the disk.  This avoids mke2fs dirtying a
+lot of buffer cache memory, which may impact other applications running
+on a busy server.  This option will cause mke2fs to run much more
+slowly, however, so there is a tradeoff to using direct I/O.
+.TP
+.BI \-e " error-behavior"
+Change the behavior of the kernel code when errors are detected.
+In all cases, a file system error will cause
+.BR e2fsck (8)
+to check the file system on the next boot.
+.I error-behavior
+can be one of the following:
+.RS 1.2i
+.TP 1.2i
+.B continue
+Continue normal execution.
+.TP
+.B remount-ro
+Remount file system read-only.
+.TP
+.B panic
+Cause a kernel panic.
+.RE
+.TP
 .BI \-E " extended-options"
-Set extended options for the filesystem.  Extended options are comma
+Set extended options for the file system.  Extended options are comma
 separated, and may take an argument using the equals ('=') sign.  The
 .B \-E
 option used to be
@@ -194,33 +278,72 @@ in earlier versions of
 .BR mke2fs .
 The
 .B \-R
-option is still accepted for backwards compatibility.   The
-following extended options are supported:
+option is still accepted for backwards compatibility, but is deprecated.
+The following extended options are supported:
 .RS 1.2i
 .TP
+.BI encoding= encoding-name
+Enable the
+.I casefold
+feature in the super block and set
+.I encoding-name
+as the encoding to be used.  If
+.I encoding-name
+is not specified, the encoding defined in
+.BR mke2fs.conf (5)
+is used.
+.TP
+.BI encoding_flags= encoding-flags
+Define parameters for file name character encoding operations.  If a
+flag is not changed using this parameter, its default value is used.
+.I encoding-flags
+should be a comma-separated lists of flags to be enabled.  To disable a
+flag, add it to the list with the prefix "no".
+
+The only flag that can be set right now is
+.I strict
+which means that invalid strings should be rejected by the file system.
+In the default configuration, the
+.I strict
+flag is disabled.
+.TP
+.BI mmp_update_interval= interval
+Adjust the initial MMP update interval to
+.I interval
+seconds.  Specifying an
+.I interval
+of 0 means to use the default interval.  The specified interval must
+be less than 300 seconds.  Requires that the
+.B mmp
+feature be enabled.
+.TP
 .BI stride= stride-size
-Configure the filesystem for a RAID array with
+Configure the file system for a RAID array with
 .I stride-size
-filesystem blocks. This is the number of blocks read or written to disk
+file system blocks. This is the number of blocks read or written to disk
 before moving to the next disk, which is sometimes referred to as the
 .I chunk size.
-This mostly affects placement of filesystem metadata like bitmaps at
+This mostly affects placement of file system metadata like bitmaps at
 .B mke2fs
 time to avoid placing them on a single disk, which can hurt performance.
 It may also be used by the block allocator.
 .TP
-.BI stripe-width= stripe-width
-Configure the filesystem for a RAID array with
+.BI stripe_width= stripe-width
+Configure the file system for a RAID array with
 .I stripe-width
-filesystem blocks per stripe. This is typically stride-size * N, where
+file system blocks per stripe. This is typically stride-size * N, where
 N is the number of data-bearing disks in the RAID (e.g. for RAID 5 there is one
 parity disk, so N will be the number of disks in the array minus 1).
 This allows the block allocator to prevent read-modify-write of the
 parity in a RAID stripe if possible when the data is written.
 .TP
+.BI offset= offset
+Create the file system at an offset from the beginning of the device or
+file.  This can be useful when creating disk images for virtual machines.
+.TP
 .BI resize= max-online-resize
 Reserve enough space so that the block group descriptor table can grow
-to support a filesystem that has
+to support a file system that has
 .I max-online-resize
 blocks.
 .TP
@@ -228,62 +351,115 @@ blocks.
 If enabled and the uninit_bg feature is enabled, the inode table will
 not be fully initialized by
 .BR mke2fs .
-This speeds up filesystem
+This speeds up file system
 initialization noticeably, but it requires the kernel to finish
-initializing the filesystem in the background when the filesystem is
+initializing the file system in the background when the file system is
 first mounted.  If the option value is omitted, it defaults to 1 to
-enable lazy inode table initialization.
+enable lazy inode table zeroing.
+.TP
+.B lazy_journal_init\fR[\fB= \fI<0 to disable, 1 to enable>\fR]
+If enabled, the journal inode will not be fully zeroed out by
+.BR mke2fs .
+This speeds up file system initialization noticeably, but carries some
+small risk if the system crashes before the journal has been overwritten
+entirely one time.  If the option value is omitted, it defaults to 1 to
+enable lazy journal inode zeroing.
+.TP
+.B no_copy_xattrs
+Normally
+.B mke2fs
+will copy the extended attributes of the files in the directory
+hierarchy specified via the (optional)
+.B \-d
+option.  This will disable the copy and leaves the files in the newly
+created file system without any extended attributes.
+.TP
+.BI num_backup_sb= <0|1|2>
+If the
+.B sparse_super2
+file system feature is enabled this option controls whether there will
+be 0, 1, or 2 backup superblocks created in the file system.
+.TP
+.B packed_meta_blocks\fR[\fB= \fI<0 to disable, 1 to enable>\fR]
+Place the allocation bitmaps and the inode table at the beginning of the
+disk.  This option requires that the flex_bg file system feature to be
+enabled in order for it to have effect, and will also create the journal
+at the beginning of the file system.  This option is useful for flash
+devices that use SLC flash at the beginning of the disk.
+It also maximizes the range of contiguous data blocks, which
+can be useful for certain specialized use cases, such as supported
+Shingled Drives.
+.TP
+.BI root_owner [=uid:gid]
+Specify the numeric user and group ID of the root directory.  If no UID:GID
+is specified, use the user and group ID of the user running \fBmke2fs\fR.
+In \fBmke2fs\fR 1.42 and earlier the UID and GID of the root directory were
+set by default to the UID and GID of the user running the mke2fs command.
+The \fBroot_owner=\fR option allows explicitly specifying these values,
+and avoid side-effects for users that do not expect the contents of the
+file system to change based on the user running \fBmke2fs\fR.
 .TP
 .B test_fs
-Set a flag in the filesystem superblock indicating that it may be
-mounted using experimental kernel code, such as the ext4dev filesystem.
+Set a flag in the file system superblock indicating that it may be
+mounted using experimental kernel code, such as the ext4dev file system.
 .TP
-.BI discard
+.B discard
 Attempt to discard blocks at mkfs time (discarding blocks initially is useful
 on solid state devices and sparse / thin-provisioned storage). When the device
 advertises that discard also zeroes data (any subsequent read after the discard
 and before write returns zero), then mark all not-yet-zeroed inode tables as
-zeroed. This significantly speeds up filesystem initialization. This is set
+zeroed. This significantly speeds up file system initialization. This is set
 as default.
 .TP
-.BI nodiscard
+.B nodiscard
 Do not attempt to discard blocks at mkfs time.
-.RE
 .TP
-.BI \-f " fragment-size"
-Specify the size of fragments in bytes.
+.B quotatype
+Specify the which  quota types (usrquota, grpquota, prjquota) which
+should be enabled in the created file system.  The argument of this
+extended option should be a colon separated list.  This option has
+effect only if the
+.B quota
+feature is set.   The default quota types to be initialized if this
+option is not specified is both user and group quotas.  If the project
+feature is enabled that project quotas will be initialized as well.
+.RE
 .TP
 .B \-F
 Force
 .B mke2fs
-to create a filesystem, even if the specified device is not a partition
+to create a file system, even if the specified device is not a partition
 on a block special device, or if other parameters do not make sense.
 In order to force
 .B mke2fs
-to create a filesystem even if the filesystem appears to be in use
+to create a file system even if the file system appears to be in use
 or is mounted (a truly dangerous thing to do), this option must be
 specified twice.
 .TP
 .BI \-g " blocks-per-group"
 Specify the number of blocks in a block group.  There is generally no
 reason for the user to ever set this parameter, as the default is optimal
-for the filesystem.  (For administrators who are creating
-filesystems on RAID arrays, it is preferable to use the
+for the file system.  (For administrators who are creating
+file systems on RAID arrays, it is preferable to use the
 .I stride
 RAID parameter as part of the
 .B \-E
 option rather than manipulating the number of blocks per group.)
 This option is generally used by developers who
 are developing test cases.
+.IP
+If the bigalloc feature is enabled, the
+.B \-g
+option will specify the number of clusters in a block group.
 .TP
 .BI \-G " number-of-groups"
 Specify the number of block groups that will be packed together to
 create a larger virtual block group (or "flex_bg group") in an
-ext4 filesystem.  This improves meta-data locality and performance
+ext4 file system.  This improves meta-data locality and performance
 on meta-data heavy workloads.  The number of groups must be a power
-of 2 and may only be specified if the 
+of 2 and may only be specified if the
 .B flex_bg
-filesystem feature is enabled.
+file system feature is enabled.
 .TP
 .BI \-i " bytes-per-inode"
 Specify the bytes/inode ratio.
@@ -293,35 +469,42 @@ creates an inode for every
 bytes of space on the disk.  The larger the
 .I bytes-per-inode
 ratio, the fewer inodes will be created.  This value generally shouldn't
-be smaller than the blocksize of the filesystem, since in that case more
+be smaller than the blocksize of the file system, since in that case more
 inodes would be made than can ever be used.  Be warned that it is not
-possible to expand the number
-of inodes on a filesystem after it is created, so be careful deciding the
-correct value for this parameter.
+possible to change this ratio on a file system after it is created, so be
+careful deciding the correct value for this parameter.  Note that resizing
+a file system changes the number of inodes to maintain this ratio.
 .TP
 .BI \-I " inode-size"
 Specify the size of each inode in bytes.
-.B mke2fs
-creates 256-byte inodes by default.  In kernels after 2.6.10 and some
-earlier vendor kernels it is possible to utilize inodes larger than
-128 bytes to store
-extended attributes for improved performance.  The
+The
 .I inode-size
 value must be a power of 2 larger or equal to 128.  The larger the
 .I inode-size
 the more space the inode table will consume, and this reduces the usable
-space in the filesystem and can also negatively impact performance.
-Extended attributes
-stored in large inodes are not visible with older kernels, and such
-filesystems will not be mountable with 2.4 kernels at all.  It is not
-possible to change this value after the filesystem is created.
+space in the file system and can also negatively impact performance.
+It is not
+possible to change this value after the file system is created.
+.IP
+File systems with an inode size of 128 bytes do not support timestamps
+beyond January 19, 2038.  Inodes which are 256 bytes or larger will
+support extended timestamps, project id's, and the ability to store some
+extended attributes in the inode table for improved performance.
+.IP
+The default inode size is controlled by the
+.BR mke2fs.conf (5)
+file.  In the
+.B mke2fs.conf
+file shipped with e2fsprogs, the default inode size is 256 bytes for
+most file systems, except for small file systems where the inode size
+will be 128 bytes.
 .TP
 .B \-j
-Create the filesystem with an ext3 journal.  If the
+Create the file system with an ext3 journal.  If the
 .B \-J
 option is not specified, the default journal parameters will be used to
-create an appropriately sized journal (given the size of the filesystem)
-stored within the filesystem.  Note that you must be using a kernel
+create an appropriately sized journal (given the size of the file system)
+stored within the file system.  Note that you must be using a kernel
 which has ext3 support in order to actually make use of the journal.
 .TP
 .BI \-J " journal-options"
@@ -332,15 +515,44 @@ The following journal options are supported:
 .RS 1.2i
 .TP
 .BI size= journal-size
-Create an internal journal (i.e., stored inside the filesystem) of size
+Create an internal journal (i.e., stored inside the file system) of size
 .I journal-size
 megabytes.
-The size of the journal must be at least 1024 filesystem blocks
+The size of the journal must be at least 1024 file system blocks
 (i.e., 1MB if using 1k blocks, 4MB if using 4k blocks, etc.)
-and may be no more than 102,400 filesystem blocks.
+and may be no more than 10,240,000 file system blocks or half the total
+file system size (whichever is smaller)
+.TP
+.BI fast_commit_size= fast-commit-size
+Create an additional fast commit journal area of size
+.I fast-commit-size
+kilobytes.
+This option is only valid if
+.B fast_commit
+feature is enabled
+on the file system. If this option is not specified and if
+.B fast_commit
+feature is turned on, fast commit area size defaults to
+.I journal-size
+/ 64 megabytes. The total size of the journal with
+.B fast_commit
+feature set is
+.I journal-size
++ (
+.I fast-commit-size
+* 1024) megabytes. The total journal size may be no more than
+10,240,000 file system blocks or half the total file system size
+(whichever is smaller).
+.TP
+.BI location =journal-location
+Specify the location of the journal.  The argument
+.I journal-location
+can either be specified as a block number, or if the number has a units
+suffix (e.g., 'M', 'G', etc.) interpret it as the offset from the
+beginning of the file system.
 @JDEV@.TP
 @JDEV@.BI device= external-journal
-@JDEV@Attach the filesystem to the journal block device located on
+@JDEV@Attach the file system to the journal block device located on
 @JDEV@.IR external-journal .
 @JDEV@The external
 @JDEV@journal must already have been created using the command
@@ -351,9 +563,9 @@ and may be no more than 102,400 filesystem blocks.
 @JDEV@Note that
 @JDEV@.I external-journal
 @JDEV@must have been created with the
-@JDEV@same block size as the new filesystem.
+@JDEV@same block size as the new file system.
 @JDEV@In addition, while there is support for attaching
-@JDEV@multiple filesystems to a single external journal,
+@JDEV@multiple file systems to a single external journal,
 @JDEV@the Linux kernel and
 @JDEV@.BR e2fsck (8)
 @JDEV@do not currently support shared external journals yet.
@@ -375,7 +587,7 @@ and may be no more than 102,400 filesystem blocks.
 @JDEV@.IP
 @JDEV@Only one of the
 @JDEV@.BR size " or " device
-@JDEV@options can be given for a filesystem.
+@JDEV@options can be given for a file system.
 .TP
 .BI \-l " filename"
 Read the bad blocks list from
@@ -395,41 +607,41 @@ will automatically pass the correct parameters to the
 program.
 .TP
 .BI \-L " new-volume-label"
-Set the volume label for the filesystem to
+Set the volume label for the file system to
 .IR new-volume-label .
 The maximum length of the
 volume label is 16 bytes.
 .TP
 .BI \-m " reserved-blocks-percentage"
-Specify the percentage of the filesystem blocks reserved for
+Specify the percentage of the file system blocks reserved for
 the super-user.  This avoids fragmentation, and allows root-owned
 daemons, such as
 .BR syslogd (8),
 to continue to function correctly after non-privileged processes are
-prevented from writing to the filesystem.  The default percentage
+prevented from writing to the file system.  The default percentage
 is 5%.
 .TP
 .BI \-M " last-mounted-directory"
-Set the last mounted directory for the filesystem.  This might be useful
+Set the last mounted directory for the file system.  This might be useful
 for the sake of utilities that key off of the last mounted directory to
-determine where the filesystem should be mounted.
+determine where the file system should be mounted.
 .TP
 .B \-n
 Causes
 .B mke2fs
-to not actually create a filesystem, but display what it
-would do if it were to create a filesystem.  This can be used to
+to not actually create a file system, but display what it
+would do if it were to create a file system.  This can be used to
 determine the location of the backup superblocks for a particular
-filesystem, so long as the
+file system, so long as the
 .B mke2fs
 parameters that were passed when the
-filesystem was originally created are used again.  (With the
+file system was originally created are used again.  (With the
 .B \-n
 option added, of course!)
 .TP
 .BI \-N " number-of-inodes"
 Overrides the default calculation of the number of inodes that should be
-reserved for the filesystem (which is based on the number of blocks and
+reserved for the file system (which is based on the number of blocks and
 the
 .I bytes-per-inode
 ratio).  This allows the user to specify the number
@@ -437,13 +649,13 @@ of desired inodes directly.
 .TP
 .BI \-o " creator-os"
 Overrides the default value of the "creator operating system" field of the
-filesystem.  The creator field is set by default to the name of the OS the
+file system.  The creator field is set by default to the name of the OS the
 .B mke2fs
 executable was compiled for.
 .TP
-.B "\-O \fIfeature\fR[,...]"
-Create a filesystem with the given features (filesystem options),
-overriding the default filesystem options.  The features that are
+.B "\-O \fR[^]\fIfeature\fR[,...]"
+Create a file system with the given features (file system options),
+overriding the default file system options.  The features that are
 enabled by default are specified by the
 .I base_features
 relation, either in the
@@ -459,93 +671,31 @@ option, further modified by the
 .I features
 relation found in the
 .I [fs_types]
-subsections for the filesystem and usage types.  See the
+subsections for the file system and usage types.  See the
 .BR mke2fs.conf (5)
 manual page for more details.
-The filesystem type-specific configuration setting found in the
+The file system type-specific configuration setting found in the
 .I [fs_types]
 section will override the global default found in
 .IR [defaults] .
 .sp
-The filesystem feature set will be further edited
+The file system feature set will be further edited
 using either the feature set specified by this option,
 or if this option is not given, by the
 .I default_features
-relation for the filesystem type being created, or in the
+relation for the file system type being created, or in the
 .I [defaults]
 section of the configuration file.
 .sp
-The filesystem feature set is comprised of a list of features, separated
+The file system feature set is comprised of a list of features, separated
 by commas, that are to be enabled.  To disable a feature, simply
-prefix the feature name with a  caret ('^') character.  The
-pseudo-filesystem feature "none" will clear all filesystem features.
-.RS 1.2i
-.TP
-.B dir_index
-Use hashed b-trees to speed up lookups in large directories.
-.TP
-.B extent
-Instead of using the indirect block scheme for storing the location of
-data blocks in an inode, use extents instead.  This is a much more
-efficient encoding which speeds up filesystem access, especially for
-large files.
+prefix the feature name with a caret ('^') character.
+Features with dependencies will not be removed successfully.
+The pseudo-file system feature "none" will clear all file system features.
 .TP
-.B filetype
-Store file type information in directory entries.
-.TP
-.B flex_bg
-Allow the per-block group metadata (allocation bitmaps and inode tables)
-to be placed anywhere on the storage media.  In addition,
-.B mke2fs
-will place the per-block group metadata together starting at the first
-block group of each "flex_bg group".   The size of the flex_bg group
-can be specified using the 
-.B \-G
-option.
-.TP
-.B has_journal
-Create an ext3 journal (as if using the
-.B \-j
-option).
-@JDEV@.TP
-@JDEV@.B journal_dev
-@JDEV@Create an external ext3 journal on the given device
-@JDEV@instead of a regular ext2 filesystem.
-@JDEV@Note that
-@JDEV@.I external-journal
-@JDEV@must be created with the same
-@JDEV@block size as the filesystems that will be using it.
-.TP
-.B large_file
-Filesystem can contain files that are greater than 2GB.  (Modern kernels
-set this feature automatically when a file > 2GB is created.)
-.TP
-.B resize_inode
-Reserve space so the block group descriptor table may grow in the future.
-Useful for online resizing using
-.BR resize2fs .
-By default
-.B mke2fs
-will attempt to reserve enough space so that the
-filesystem may grow to 1024 times its initial size.  This can be changed
-using the
-.B resize
-extended option.
-.TP
-.B sparse_super
-Create a filesystem with fewer superblock backup copies
-(saves space on large filesystems).
-.TP
-.B uninit_bg
-Create a filesystem without initializing all of the block groups.  This
-feature also enables checksums and highest-inode-used statistics in each
-blockgroup.  This feature can
-speed up filesystem creation time noticeably (if lazy_itable_init is
-enabled), and can also reduce
-.BR e2fsck
-time dramatically.  It is only supported by the ext4 filesystem in
-recent Linux kernels.
-.RE
+For more information about the features which can be set, please see
+the manual page
+.BR ext4 (5).
 .TP
 .B \-q
 Quiet execution.  Useful if
@@ -553,82 +703,118 @@ Quiet execution.  Useful if
 is run in a script.
 .TP
 .BI \-r " revision"
-Set the filesystem revision for the new filesystem.  Note that 1.2
-kernels only support revision 0 filesystems.  The default is to
-create revision 1 filesystems.
+Set the file system revision for the new file system.  Note that 1.2
+kernels only support revision 0 file systems.  The default is to
+create revision 1 file systems.
 .TP
 .B \-S
-Write superblock and group descriptors only.  This is useful if all of
+Write superblock and group descriptors only.  This is an extreme
+measure to be taken only in the very unlikely case that all of
 the superblock and backup superblocks are corrupted, and a last-ditch
-recovery method is desired.  It causes
+recovery method is desired by experienced users.  It causes
 .B mke2fs
-to reinitialize the
-superblock and group descriptors, while not touching the inode table
-and the block and inode bitmaps.  The
+to reinitialize the superblock and group descriptors, while not
+touching the inode table and the block and inode bitmaps.  The
 .B e2fsck
 program should be run immediately after this option is used, and there
-is no guarantee that any data will be salvageable.  It is critical to
-specify the correct filesystem blocksize when using this option,
-or there is no chance of recovery.
+is no guarantee that any data will be salvageable.  Due to the wide
+variety of possible options to
+.B mke2fs
+that affect the on-disk layout, it is critical to specify exactly
+the same format options, such as blocksize, fs-type, feature flags, and
+other tunables when using this option, or the file system will be further
+corrupted.  In some cases, such as file systems that have been resized,
+or have had features enabled after format time, it is impossible to
+overwrite all of the superblocks correctly, and at least some file system
+corruption will occur.  It is best to run this on a full copy of the
+file system so other options can be tried if this doesn't work.
 .\" .TP
 .\" .BI \-t " test"
 .\" Check the device for bad blocks before creating the file system
 .\" using the specified test.
 .TP
 .BI \-t " fs-type"
-Specify the filesystem type (i.e., ext2, ext3, ext4, etc.) that is to be created.
+Specify the file system type (i.e., ext2, ext3, ext4, etc.) that is
+to be created.
 If this option is not specified,
 .B mke2fs
 will pick a default either via how
 the command was run (for example, using a name of the form mkfs.ext2,
 mkfs.ext3, etc.) or via a default as defined by the
-.BR /etc/mke2fs.conf (5)
-file.   This option controls which filesystem options are used by
+.B /etc/mke2fs.conf
+file.   This option controls which file system options are used by
 default, based on the
 .B fstypes
 configuration stanza in
-.BR /etc/mke2fs.conf (5).
+.BR /etc/mke2fs.conf .
 .sp
 If the
 .B \-O
-option is used to explicitly add or remove filesystem options that
-should be set in the newly created filesystem, the
-resulting filesystem may not be supported by the requested
+option is used to explicitly add or remove file system options that
+should be set in the newly created file system, the
+resulting file system may not be supported by the requested
 .IR fs-type .
 (e.g., "\fBmke2fs \-t ext3 \-O extent /dev/sdXX\fR" will create a
-filesystem that is not supported by the ext3 implementation as found in
+file system that is not supported by the ext3 implementation as found in
 the Linux kernel; and "\fBmke2fs \-t ext3 \-O ^has_journal /dev/hdXX\fR"
-will create a filesystem that does not have a journal and hence will not
-be supported by the ext3 filesystem code in the Linux kernel.)
+will create a file system that does not have a journal and hence will not
+be supported by the ext3 file system code in the Linux kernel.)
 .TP
 .BI \-T " usage-type[,...]"
-Specify how the filesystem is going to be used, so that
+Specify how the file system is going to be used, so that
 .B mke2fs
-can choose optimal filesystem parameters for that use.  The usage
+can choose optimal file system parameters for that use.  The usage
 types that are supported are defined in the configuration file
-.BR /etc/mke2fs.conf (5).
+.BR /etc/mke2fs.conf .
 The user may specify one or more usage types
 using a comma separated list.
 .sp
 If this option is is not specified,
 .B mke2fs
-will pick a single default usage type based on the size of the filesystem to
-be created.  If the filesystem size is less than or equal to 3 megabytes,
+will pick a single default usage type based on the size of the file system to
+be created.  If the file system size is less than 3 megabytes,
 .B mke2fs
-will use the filesystem type
+will use the file system type
 .IR floppy .
-If the filesystem size is greater than 3 but less than or equal to
+If the file system size is greater than or equal to 3 but less than
 512 megabytes,
 .BR mke2fs (8)
-will use the filesystem
+will use the file system type
 .IR small .
+If the file system size is greater than or equal to 4 terabytes but less than
+16 terabytes,
+.BR mke2fs (8)
+will use the file system type
+.IR big .
+If the file system size is greater than or equal to 16 terabytes,
+.BR mke2fs (8)
+will use the file system type
+.IR huge .
 Otherwise,
 .BR mke2fs (8)
-will use the default filesystem type
+will use the default file system type
 .IR default .
 .TP
 .BI \-U " UUID"
-Create the filesystem with the specified UUID.
+Set the universally unique identifier (UUID) of the file system to
+.IR UUID .
+The format of the UUID is a series of hex digits separated by hyphens,
+like this:
+"c1b9d5a2-f162-11cf-9ece-0020afc76f16".
+The
+.I UUID
+parameter may also be one of the following:
+.RS 1.2i
+.TP
+.I clear
+clear the file system UUID
+.TP
+.I random
+generate a new randomly-generated UUID
+.TP
+.I time
+generate a new time-based UUID
+.RE
 .TP
 .B \-v
 Verbose execution.
@@ -637,18 +823,49 @@ Verbose execution.
 Print the version number of
 .B mke2fs
 and exit.
+.TP
+.BI \-z " undo_file"
+Before overwriting a file system block, write the old contents of the block to
+an undo file.  This undo file can be used with e2undo(8) to restore the old
+contents of the file system should something go wrong.  If the empty string is
+passed as the undo_file argument, the undo file will be written to a file named
+mke2fs-\fIdevice\fR.e2undo in the directory specified via the
+\fIE2FSPROGS_UNDO_DIR\fR environment variable or the \fIundo_dir\fR directive
+in the configuration file.
+
+WARNING: The undo file cannot be used to recover from a power or system crash.
+.SH ENVIRONMENT
+.TP
+.B MKE2FS_SYNC
+If set to non-zero integer value, its value is used to determine how often
+.BR sync (2)
+is called during inode table initialization.
+.TP
+.B MKE2FS_CONFIG
+Determines the location of the configuration file (see
+.BR mke2fs.conf (5)).
+.TP
+.B MKE2FS_FIRST_META_BG
+If set to non-zero integer value, its value is used to determine first meta
+block group. This is mostly for debugging purposes.
+.TP
+.B MKE2FS_DEVICE_SECTSIZE
+If set to non-zero integer value, its value is used to determine logical
+sector size of the
+.IR device .
+.TP
+.B MKE2FS_DEVICE_PHYS_SECTSIZE
+If set to non-zero integer value, its value is used to determine physical
+sector size of the
+.IR device .
+.TP
+.B MKE2FS_SKIP_CHECK_MSG
+If set, do not show the message of file system automatic check caused by
+mount count or check interval.
 .SH AUTHOR
 This version of
 .B mke2fs
 has been written by Theodore Ts'o <tytso@mit.edu>.
-.SH BUGS
-.B mke2fs
-accepts the
-.B \-f
-option but currently ignores it because the second
-extended file system does not support fragments yet.
-.br
-There may be other ones.  Please, report them to the author.
 .SH AVAILABILITY
 .B mke2fs
 is part of the e2fsprogs package and is available from
@@ -658,4 +875,5 @@ http://e2fsprogs.sourceforge.net.
 .BR badblocks (8),
 .BR dumpe2fs (8),
 .BR e2fsck (8),
-.BR tune2fs (8)
+.BR tune2fs (8),
+.BR ext4 (5)