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e2fsprogs: mke2fs manpage updates

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I've added documentation for all available filesystem features
settable by mke2fs.
* Features now include the kernel constant attached to the function.
* Some pre-existing feature explanations have been expanded based on
ext4.wiki.kernel.org.

[ Edited by tytso for stylistic and correctness. ]

Addresses-Debian-Bug: #586218

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Uri Corin 2013-12-16 00:53:35 -05:00 committed by Theodore Ts'o
parent fbabd5c44c
commit 4727c67dc2
1 changed files with 136 additions and 32 deletions
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168
misc/mke2fs.8.in
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@ -293,11 +293,11 @@ as default.
Do not attempt to discard blocks at mkfs time.
@QUOTA_MAN_COMMENT@.TP
@QUOTA_MAN_COMMENT@.BI quotatype
@QUOTA_MAN_COMMENT@Specify which quota type ('usr' or 'grp') is to be initialized. This
@QUOTA_MAN_COMMENT@option has any effect only if
@QUOTA_MAN_COMMENT@Specify which quota type ('usr' or 'grp') is to be
@QUOTA_MAN_COMMENT@initialized. This option has effect only if
@QUOTA_MAN_COMMENT@.B quota
@QUOTA_MAN_COMMENT@feature is set. Without this extended option, the default behavior is to
@QUOTA_MAN_COMMENT@initialize both user and group quotas.
@QUOTA_MAN_COMMENT@feature is set. Without this extended option, the default
@QUOTA_MAN_COMMENT@behavior is to initialize both user and group quotas.
.RE
.TP
.BI \-f " fragment-size"
@ -532,11 +532,22 @@ section of the configuration file.
.sp
The filesystem 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.
prefix the feature name with a caret ('^') or a minus ('-') character.
Features with dependents will not be removed successfully.
The pseudo-filesystem feature "none" will clear all filesystem features.
.RS 1.2i
.TP
.B 64bit
.br
Enables the file system to be larger than 2^32 blocks. This feature is set
automatically, as needed, but it can be useful to specify this feature
explicitly if the file system might need to be resized larger than 2^32
blocks, even if it was smaller than that threshold when it was
originally created. Note that some older kernels and older versions
of e2fsprogs will not support file systems with this feature enabled.
.TP
.B bigalloc
.br
This feature enables clustered allocation, so that the unit of
allocation is a power of two number of blocks. That is, each bit in the
what had traditionally been known as the block allocation bitmap now
@ -550,21 +561,49 @@ for large files. The size can be specified using the
The bigalloc feature is still under development, and may not be fully
supported with your kernel or may have various bugs. Please see the web
page http://ext4.wiki.kernel.org/index.php/Bigalloc for details.
May clash with delayed allocation (see
.BR nodelalloc mount option).
.IP
This feature requires that the
.B extent
features be enabled.
.TP
.B dir_index
.br
Use hashed b-trees to speed up lookups in large directories.
.TP
.B extents
.B dir_nlink
.br
Allow more than 65000 subdirectories per directory.
.TP
.B extent
.br
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. (Note: both extent and extents are accepted for
large files. (Note: both
.B extent
and
.B extents
are accepted as valid names for this feature for
historical/backwards compatibility reasons.)
.TP
.B extra_isize
.br
This feature enables storage of nanosecond timestamps and creation
time, if the inode size is larger than 256 bytes or larger.
.TP
.B ext_attr
.br
This feature enables the use of extended attributes.
.TP
.B filetype
Store file type information in directory entries.
.br
This feature enables the storage file type information in directory
entries. It is normally enabled by default for all file system types.
.TP
.B flex_bg
.br
Allow the per-block group metadata (allocation bitmaps and inode tables)
to be placed anywhere on the storage media. In addition,
.B mke2fs
@ -575,28 +614,82 @@ can be specified using the
option.
.TP
.B has_journal
Create an ext3 journal (as if using the
.br
Create a journal to ensure filesystem consistency even across unclean
shutdowns. Setting the filesystem feature is equivalent to 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.
option.
.TP
.B huge_file
.br
Allows files larger than 2TiB in size.
.TP
.B journal_dev
.br
Creates an external ext3 journal on the given device
instead of a regular ext2 filesystem.
Note that
.I external-journal
must be created with the same
block size as the filesystems that will be using it.
.IP
Once ready, use
.BR mke2fs (8)
or
.BR tune2fs(8)
with
.B \-J
.BR device= <external-device>
to direct a filesystem to the journaling device (see journal-options).
.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.)
.br
Filesystem can contain files that are greater than 2GiB. (Modern kernels
set this feature automatically when a file > 2GiB is created.)
.\" .TP
.\" .B metadata_csum
.\" .br
.\" Filesystem supports metadata checksumming. This feature enables a
.\" superset of the functionality of the
.\" .B uninit_bg
.\" feature.
.\" .br
.\" .B Future feature, available in e2fsprogs 1.43-WIP
.TP
.B meta_bg
.br
This feature allows file systems to be resized on-line without explicitly
needing to reserve space for growth in the size of the block group
descriptors. This scheme is also used to resize file systems which are
larger than 2^32 blocks. It is not recommended that this feature be set
when a file system is created, since this alternate method of storing
the block group descriptor will slow down the time needed to mount the
file system, and newer kernels can automatically set this feature as
necessary when doing an online resize and no more reserved space is
available in the resize inode.
.TP
.B mmp
.br
Multiple mount protection (MMP) feature. MMP helps to
protect the filesystem from being multiply mounted and is useful in
shared storage environments.
@QUOTA_MAN_COMMENT@.TP
@QUOTA_MAN_COMMENT@.B quota
@QUOTA_MAN_COMMENT@Create quota inodes (inode# 3 for userquota and inode# 4 for group quota) and
@QUOTA_MAN_COMMENT@set them in the superblock. With this feature, the quotas will be enabled
@QUOTA_MAN_COMMENT@.br
@QUOTA_MAN_COMMENT@Create quota inodes (inode #3 for userquota and inode
@QUOTA_MAN_COMMENT@#4 for group quota) and set them in the superblock.
@QUOTA_MAN_COMMENT@With this feature, the quotas will be enabled
@QUOTA_MAN_COMMENT@automatically when the filesystem is mounted.
@QUOTA_MAN_COMMENT@.IP
@QUOTA_MAN_COMMENT@Causes the quota files (i.e., user.quota and
@QUOTA_MAN_COMMENT@group.quota which existed
@QUOTA_MAN_COMMENT@in the older quota design) to be hidden inodes.
@QUOTA_MAN_COMMENT@.IP
@QUOTA_MAN_COMMENT@.B Not defined by default,
@QUOTA_MAN_COMMENT@see https://ext4.wiki.kernel.org/index.php/Quota
.TP
.B resize_inode
.br
Reserve space so the block group descriptor table may grow in the future.
Useful for online resizing using
.BR resize2fs .
@ -607,20 +700,30 @@ filesystem may grow to 1024 times its initial size. This can be changed
using the
.B resize
extended option.
.IP
This feature requires that the
.B sparse_super
feature be enabled.
.TP
.B sparse_super
.br
Create a filesystem with fewer superblock backup copies
(saves space on large filesystems).
(saves space on large filesystems). This feature is normally enabled by
default for all file systems.
.TP
.B uninit_bg
.br
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.
feature allows the kernel to initialize bitmaps and inode tables
and keep a high watermark for the unused inodes in a filesystem, to reduce
.BR e2fsck (8)
time. The result is that it can speed up filesystem creation time noticeably
(if lazy_itable_init is enabled).
.IP
This first e2fsck run after enabling this feature will take the
full time, but subsequent e2fsck runs will take only a fraction of the
original time, depending on how full the file system is.
It is only supported by the ext4 filesystem in recent Linux kernels.
.RE
.TP
.B \-q
@ -652,7 +755,8 @@ or there is no chance of recovery.
.\" 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 filesystem 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