.BR dumpe2fs (8),
.BR tune2fs (8),
.BR e2fsck (8),
-.BR mke2fs (8)
+.BR mke2fs (8),
+.BR ext4 (5)
e2label.8 $(FINDFS_MAN) $(BLKID_MAN) $(E2IMAGE_MAN) \
logsave.8 filefrag.8 e2freefrag.8 e2undo.8 \
$(UUIDD_MAN) $(E4DEFRAG_MAN) @FSCK_MAN@
-FMANPAGES= mke2fs.conf.5
+FMANPAGES= mke2fs.conf.5 ext4.5
UPROGS= chattr lsattr @UUID_CMT@ uuidgen
UMANPAGES= chattr.1 lsattr.1 @UUID_CMT@ uuidgen.1
$(E) " SUBST $@"
$(Q) $(SUBSTITUTE_UPTIME) $(srcdir)/mke2fs.conf.5.in mke2fs.conf.5
+ext4.5: $(DEP_SUBSTITUTE) $(srcdir)/ext4.5.in
+ $(E) " SUBST $@"
+ $(Q) $(SUBSTITUTE_UPTIME) $(srcdir)/$@.in $@
+
e2label.8: $(DEP_SUBSTITUTE) $(srcdir)/e2label.8.in
$(E) " SUBST $@"
$(Q) $(SUBSTITUTE_UPTIME) $(srcdir)/e2label.8.in e2label.8
$(ES) " INSTALL_DATA $(man5dir)/$$i"; \
$(INSTALL_DATA) $$i $(DESTDIR)$(man5dir)/$$i; \
done
+ $(Q) for i in ext2 ext3; do \
+ $(ES) " LINK $$i.5"; \
+ (cd $(DESTDIR)$(man5dir); \
+ $(LN) $(LINK_INSTALL_FLAGS) ext4.5 $$i.5); \
+ done
$(Q) if test -f $(DESTDIR)$(root_sysconfdir)/mke2fs.conf; then \
if cmp -s $(DESTDIR)$(root_sysconfdir)/mke2fs.conf \
mke2fs.conf; then \
$(RM) -f $(DESTDIR)$(man8dir)/mkfs.ext2.8 \
$(DESTDIR)$(man8dir)/mkfs.ext3.8 \
$(DESTDIR)$(man8dir)/mkfs.ext4.8 \
- $(DESTDIR)$(man8dir)/mkfs.ext4dev.8
+ $(DESTDIR)$(man8dir)/mkfs.ext4dev.8 \
+ $(DESTDIR)$(man8dir)/fsck.ext2.8 \
+ $(DESTDIR)$(man8dir)/fsck.ext3.8 \
+ $(DESTDIR)$(man8dir)/fsck.ext4.8 \
+ $(DESTDIR)$(man8dir)/fsck.ext4dev.8
+
for i in $(UMANPAGES); do \
$(RM) -f $(DESTDIR)$(man1dir)/$$i; \
done
for i in $(FMANPAGES); do \
$(RM) -f $(DESTDIR)$(man5dir)/$$i; \
done
+ $(Q) for i in ext2 ext3; do \
+ $(ES) " LINK $$i.5"; \
+ $(RM) -f $(DESTDIR)$(man5dir)/$$i.5; \
+ done
if cmp -s mke2fs.conf $(DESTDIR)/$(root_sysconfdir)/mke2fs.conf; then \
$(RM) $(DESTDIR)/$(root_sysconfdir)/mke2fs.conf; \
fi
.SH SEE ALSO
.BR e2fsck (8),
.BR mke2fs (8),
-.BR tune2fs (8)
+.BR tune2fs (8).
+.BR ext4 (5)
--- /dev/null
+.\" -*- nroff -*-
+.\" Copyright 1993, 1994, 1995 by Theodore Ts'o. All Rights Reserved.
+.\" This file may be copied under the terms of the GNU Public License.
+.\"
+.TH EXT4 5 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
+.SH NAME
+ext2 \- the second extended file system
+.br
+ext2 \- the third extended file system
+.br
+ext4 \- the fourth extended file system
+.SH DESCRIPTION
+The second, third, and fourth extended file systems, or ext2, ext3, and
+ext4 as they are commonly known, are Linux file systems that have
+historically been the default file system for many Linux distributions.
+They are general purpose file systems that have been designed for
+extensibility and backwards compatibility. In particular, file systems
+previously intended for use with the ext2 and ext3 file systems can be
+mounted using the ext4 file system driver, and indeed in many modern
+Linux distributions, the ext4 file system driver has been configured
+handle mount requests for ext2 and ext3 file systems.
+.SH FILE SYSTEM FEATURES
+A file system formated for ext2, ext3, or ext4 can be have some
+collection of the follow file system feature flags enabled. Some of
+these features are not supported by all implementations of the ext2,
+ext3, and ext4 file system drivers, depending on Linux kernel version in
+use. On other operating systems, such as the GNU/HURD or FreeBSD, only
+a very restrictive set of file system features may be supported in their
+implementations of ext2.
+.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 ext4 feature enabled.
+.TP
+.B bigalloc
+.br
+This ext4 feature enables clustered block 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
+indicates whether a cluster is in use or not, where a cluster is by
+default composed of 16 blocks. This feature can decrease the time
+spent on doing block allocation and brings smaller fragmentation, especially
+for large files. The size can be specified using the
+.B \-C option.
+.IP
+.B Warning:
+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 name lookups in large directories. This
+feature is supported by ext3 and ext4 file systems, and is ignored by
+ext2 file systems.
+.TP
+.B dir_nlink
+.br
+This ext4 feature allows more than 65000 subdirectories per directory.
+.TP
+.B extent
+.br
+This ext4 feature allows the mapping of logical block numbers for a
+particular inode to physical blocks on the storage device to be stored
+using an extent tree, which is a more efficient data structure than the
+traditional indirect block scheme used by the ext2 and ext3 file
+systems. The use of the extent tree decreases metadata block overhead,
+improves file system performance, and decreases the needed to run
+.BR e2fsck (8)
+on the file system.
+(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 ext4 feature reserves a specific amount of space in each inode for
+extended metadata such as nanosecond timestamps and file creation time,
+even if the current kernel does not current need to reserve this much
+space. Without this feature, the kernel will reserve the amount of
+space for features currently it currently needs, and the rest may be
+consumed by extended attributes.
+
+For this feature to be useful the inode size must be 256 bytes in size
+or larger.
+.TP
+.B ext_attr
+.br
+This feature enables the use of extended attributes. This feature is
+supported by ext2, ext3, and ext4.
+.TP
+.B filetype
+.br
+This feature enables the storage file type information in directory
+entries. This feature is supported by ext2, ext3, and ext4.
+.TP
+.TP
+.B flex_bg
+.br
+This ext4 feature allows 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
+.br
+Create a journal to ensure filesystem consistency even across unclean
+shutdowns. Setting the filesystem feature is equivalent to using the
+.B \-j
+option. This feature is supported by ext3 and ext4, and ignored by the
+ext2 file system driver.
+.TP
+.B huge_file
+.br
+This ext4 feature allows files to be larger than 2 terabytes in size.
+.TP
+.B journal_dev
+.br
+This feature is enabled on the superblock found on an external journal
+device. The block size for the external journal must be the same as the
+file system which uses it.
+.IP
+The external journal device can be used by a file system by specifying
+the
+.B \-J
+.BR device= <external-device>
+option to
+.BR mke2fs (8)
+or
+.BR tune2fs(8).
+.TP
+.B large_file
+.br
+This feature flag is set automatically by modern kernels when a file
+larger than 2 gigabytes is created. Very old kernels could not
+handle large files, so this feature flag was used to prohibit those
+kernels from mounting file systems that they could not understand.
+.\" .TP
+.\" .B metadata_csum
+.\" .br
+.\" This ext4 feature enables metadata checksumming. This feature stores
+.\" checksums for all of the filesystem metadata (superblock, group
+.\" descriptor blocks, inode and block bitmaps, directories, and
+.\" extent tree blocks). The checksum algorithm used for the metadata
+.\" blocks is different than the one used for group descriptors with the
+.\" .B uninit_bg
+.\" feature, these two features are incompatible and
+.\" .B metadata_csum
+.\" will be used preferentially instead of
+.\" .BR uninit_bg .
+.\" .br
+.\" .B Future feature, available in e2fsprogs 1.43-WIP
+.TP
+.B meta_bg
+.br
+This ext4 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
+This ext4 feature provides multiple mount protection (MMP). 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@.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 Warning:
+@QUOTA_MAN_COMMENT@The quota feature is still under development,
+@QUOTA_MAN_COMMENT@and may not be fully supported with your kernel
+@QUOTA_MAN_COMMENT@or may have various bugs. Please
+@QUOTA_MAN_COMMENT@see https://ext4.wiki.kernel.org/index.php/Quota
+@QUOTA_MAN_COMMENT@for more details.
+.TP
+.B resize_inode
+.br
+This file system feature indicates that space has been reserved so
+the block group descriptor table can be extended by the file system is
+resized while the file system is mounted. The online resize operation
+is carried out by the kernel, triggered, by
+.BR resize2fs (8).
+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.
+.IP
+This feature requires that the
+.B sparse_super
+feature be enabled.
+.TP
+.B sparse_super
+.br
+This file system feature is set on all modern ext2, ext3, and ext4 file
+system. It indicates that backup copies of the superblock and block
+group descriptors be present only on a few block groups, and not all of
+them.
+.TP
+.B uninit_bg
+.br
+This ext4 file system feature indicates that the block group descriptors
+will be protected using checksums, making it safe for
+.BR mke2fs (8)
+to create a file system without initializing all of the block groups.
+The kernel will keep a high watermark of unused inodes, and initialize
+inode tables and block lazily. This feature speeds up the time to check
+the file system using
+.BR e2fsck (8),
+and it also speeds up the time required for
+.BR mke2fs (8)
+to create the file system.
+.RE
+.SH SEE ALSO
+.BR mke2fs (8),
+.BR mke2fs.conf (5),
+.BR e2fsck (8),
+.BR dumpe2fs (8),
+.BR tune2fs (8),
+.BR debugfs (8)
@QUOTA_MAN_COMMENT@.TP
@QUOTA_MAN_COMMENT@.BI quotatype
@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@initialized. This option has effect only if the
@QUOTA_MAN_COMMENT@.B quota
@QUOTA_MAN_COMMENT@feature is set. Without this extended option, the default
@QUOTA_MAN_COMMENT@behavior is to initialize both user and group quotas.
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 ('^') or a minus ('-') character.
-Features with dependents will not be removed successfully.
+Features with dependencies 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 block 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
-indicates whether a cluster is in use or not, where a cluster is by
-default composed of 16 blocks. This feature can decrease the time
-spent on doing block allocation and brings smaller fragmentation, especially
-for large files. The size can be specified using the
-.B \-C option.
-.IP
-.B Warning:
-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 name lookups in large directories.
-.TP
-.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
-.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 reserves a specific amount of space in each inode for
-extended metadata such as nanosecond timestamps and file creation time,
-even if the current kernel does not current need to reserve this much
-space. Without this feature, the kernel will reserve the amount of
-space for features currently it currently needs, and the rest may be
-consumed by extended attributes.
-
-For this feature to be useful the inode size must be 256 bytes in size
-or larger.
-.TP
-.B ext_attr
-.br
-This feature enables the use of extended attributes.
-.TP
-.B filetype
-.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
-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
-.br
-Create a journal to ensure filesystem consistency even across unclean
-shutdowns. Setting the filesystem feature is equivalent to using the
-.B \-j
-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
-.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 stores
-.\" checksums for all of the filesystem metadata (superblock, group
-.\" descriptor blocks, inode and block bitmaps, directories, and
-.\" extent tree blocks). The checksum algorithm used for the metadata
-.\" blocks is different than the one used for group descriptors with the
-.\" .B uninit_bg
-.\" feature, these two features are incompatible and
-.\" .B metadata_csum
-.\" will be used preferentially instead of
-.\" .BR uninit_bg .
-.\" .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@.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 .
-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.
-.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). 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 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).
-.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
.BR badblocks (8),
.BR dumpe2fs (8),
.BR e2fsck (8),
-.BR tune2fs (8)
+.BR tune2fs (8),
+.BR ext4 (5)
features with commas. Filesystem features prefixed with a
caret character ('^') will be cleared in the filesystem's superblock;
filesystem features without a prefix character or prefixed with a plus
-character ('+') will be added to the filesystem.
+character ('+') will be added to the filesystem. For a detailed
+description of the file system features, please see the man page
+.BR ext4 (5).
.IP
The following filesystem features can be set or cleared using
.BR tune2fs :
.RS 1.2i
.TP
.B dir_index
-Use hashed b-trees to speed up lookups in large directories.
+Use hashed b-trees to speed up lookups for large directories.
.TP
.B dir_nlink
Allow more than 65000 subdirectories per directory.
.TP
+.B extent
+Enable the use of extent trees to store the location of data blocks in inodes.
+.TP
+.B extra_isize
+Enable the extended inode fields used by ext4.
+.TP
.B filetype
Store file type information in directory entries.
.TP
.B \-j
option.
.TP
+.B huge_file
+Support files larger than 2 terabytes in size.
+.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.)
+Filesystem can contain files that are greater than 2GB.
.TP
.B resize_inode
Reserve space so the block group descriptor table may grow in the
only supports clearing this filesystem feature.
.TP
.B mmp
-Enable or disable multiple mount protection (MMP) feature. MMP helps to
-protect the filesystem from being multiply mounted and is useful in
-shared storage environments.
+Enable or disable multiple mount protection (MMP) feature.
+@QUOTA_MAN_COMMENT@.TP
+@QUOTA_MAN_COMMENT@.B quota
+@QUOTA_MAN_COMMENT@Enable internal file system quota inodes.
.TP
.B sparse_super
Limit the number of backup superblocks to save space on large filesystems.
.TP
.B uninit_bg
-Allow the kernel to initialize bitmaps and inode tables and keep a high
-watermark for the unused inodes in a filesystem, to reduce
+Allow the kernel to initialize bitmaps and inode tables lazily, and to
+keep a high watermark for the unused inodes in a filesystem, to reduce
.BR e2fsck (8)
time. This first e2fsck run after enabling this feature will take the
full time, but subsequent e2fsck runs will take only a fraction of the
.BR debugfs (8),
.BR dumpe2fs (8),
.BR e2fsck (8),
-.BR mke2fs (8)
+.BR mke2fs (8),
+.BR ext4 (5)
projects / thirdparty / e2fsprogs.git / commitdiff
