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
+A file system formatted 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
.BR tune2fs (8).
.TP
.BR acl | noacl
-Support POSIX Access Control Lists (or not).
+Support POSIX Access Control Lists (or not). See the
+.BR acl (5)
+manual page.
.TP
.BR bsddf | minixdf
Set the behavior for the
enhanced with journaling. It supports the same options as ext2 as
well as the following additions:
.TP
-.B journal=update
-Update the ext3 filesystem's journal to the current format.
-.TP
-.B journal=inum
-When a journal already exists, this option is ignored. Otherwise, it
-specifies the number of the inode which will represent the ext3 filesystem's
-journal file; ext3 will create a new journal, overwriting the old contents
-of the file whose inode number is
-.IR inum .
-.TP
.BR journal_dev=devnum / journal_path=path
When the external journal device's major/minor numbers
have changed, these options allow the user to specify
.BR attr (5)
manual page.
.TP
-.B acl
-Enable POSIX Access Control Lists. See the
-.BR acl (5)
-manual page.
-.TP
.BR usrjquota=aquota.user | grpjquota=aquota.group | jqfmt=vfsv0
Apart from the old quota system (as in ext2, jqfmt=vfsold aka version 1 quota)
ext3 also supports journaled quotas (version 2 quota). jqfmt=vfsv0
The options
.B journal_dev, norecovery, noload, data, commit, orlov, oldalloc, [no]user_xattr
.B [no]acl, bsddf, minixdf, debug, errors, data_err, grpid, bsdgroups, nogrpid
-.B sysvgroups, resgid, resuid, sb, quota, noquota, grpquota, usrquota
+.B sysvgroups, resgid, resuid, sb, quota, noquota, nouid32, grpquota, usrquota
.B usrjquota, grpjquota and jqfmt
are backwardly compatible with ext3 or ext2.
.TP
sparse/thinly-provisioned LUNs, but it is off by default until sufficient
testing has been done.
.TP
-.B nouid32
-Disables 32-bit UIDs and GIDs. This is for
-interoperability with older kernels which only
-store and expect 16-bit values.
-.TP
.BR block_validity / noblock_validity
-This options allows to enables/disables the in-kernel facility for tracking
+This options enables/disables the in-kernel facility for tracking
filesystem metadata blocks within internal data structures. This allows multi-\c
block allocator and other routines to quickly locate extents which might
overlap with filesystem metadata blocks. This option is intended for debugging
.B dir_nlink
Allow more than 65000 subdirectories per directory.
.TP
+.B encrypt
+Enable file system level encryption.
+.B Tune2fs
+currently only supports setting this filesystem feature.
+.TP
.B extent
Enable the use of extent trees to store the location of data blocks in inodes.
+.B Tune2fs
+currently only supports setting this filesystem feature.
.TP
.B extra_isize
Enable the extended inode fields used by ext4.
.B large_file
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
-future.
-.B Tune2fs
-only supports clearing this filesystem feature.
+.B metadata_csum
+Store a checksum to protect the contents in each metadata block.
.TP
.B mmp
Enable or disable multiple mount protection (MMP) feature.
.TP
+.B project
+Enable project ID tracking. This is used for project quota tracking.
+.TP
.B quota
Enable internal file system quota inodes.
.TP
.B read-only
Force the kernel to mount the file system read-only.
.TP
+.B resize_inode
+Reserve space so the block group descriptor table may grow in the
+future.
+.B Tune2fs
+only supports clearing this filesystem feature.
+.TP
.B sparse_super
Limit the number of backup superblocks to save space on large filesystems.
+.B Tune2fs
+currently only supports setting this filesystem feature.
.TP
.B uninit_bg
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
+time. The 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.
.RE
or
.B resize_inode
filesystem features,
+the file system may require being checked using
.BR e2fsck (8)
-must be run on the filesystem to return the filesystem to a consistent state.
+to return the filesystem to a consistent state.
.B Tune2fs
will print a message requesting that the system administrator run
.BR e2fsck (8)
.SH BUGS
We haven't found any bugs yet. That doesn't mean there aren't any...
.SH AUTHOR
-.B tune2fs
+.B tune2fs
was written by Remy Card <Remy.Card@linux.org>. It is currently being
maintained by Theodore Ts'o <tytso@alum.mit.edu>.
.B tune2fs