Frequently Asked Questions
Where do I get the latest version of e2fsprogs?
How do I build e2fsprogs?
The INSTALL file in the top of the source tree gives more detailed information, but e2fsprogs uses a standard configure script, so the standard "./configure; make" will build the e2fsprogs binaries. Note that if you wish to build the ELF shared libraries, you need to add the "--enable-elf-shlibs" option to the configure invocation.
How do I mount a fresh new storage device as ext4?
For example, if the new device has been detected as /dev/sdb1 (check "dmesg" output):
Using the newly installed e2fsprogs:
cd misc/ mke2fs -E test_fs /dev/sdb1 cd debugfs/ ./debugfs -w /dev/sdb1 debugfs 1.40.5 (27-Jan-2008) debugfs: set_super_value s_flags 4 debugfs: quit
blkid /dev/sdb1 /dev/sdb1: UUID="3aa983ef-0dcd-474d-a9d3-2660ff6ef3e7" TYPE="ext4dev" mkdir /mnt/test tune2fs -j /dev/sdb1 mount -t ext4dev /dev/sdb1 /mnt/test df
Why do I get "EXT4-fs: sdb1: not marked OK to use with test code." in my dmesg?
This error arises from not executing the "mke2fs -E test_fs /dev/sdb1", which will label
How do I turned off the mballoc feature?
By default "mount" will enable mballoc feature when mounting. To turn it off:
mount -t ext4dev -o data=writeback,delalloc,extents,nomballoc /dev/sdb1 /mnt/test
How do I turned off the extent feature?
By default "mount" will enable extent feature when mounting. To turn it off:
mount -t ext4dev -o data=writeback,delalloc,noextents,mballoc /dev/sdb1 /mnt/test
CAUTION: Once extent feature has been turned on, it is not possible to mount it as ext3 anymore.
Where in the source code can I see these features enabling in action?
/* * turn on extents feature by default in ext4 filesystem * User -o noextents to turn it off */ set_opt(sbi->s_mount_opt, EXTENTS); /* * turn on mballoc feature by default in ext4 filesystem * User -o nomballoc to turn it off */
Why do I get "EXT4-fs: Unrecognized mount option "delalloc" or missing value"?
Please download the ext4 version from the git patchset, instead of using the kernel source.
What is mballoc feature? After I mounted a partition as mballoc, can I remount it as nomballoc?
Yes, it is possible, just dismount the partition first, and execute "mount" with the nomballoc feature.