Commit db29a6b4 authored Apr 21, 2009 by Bartlomiej Zolnierkiewicz Committed by Jens Axboe Apr 28, 2009

block: enable by default support for large devices and files on 32-bit archs



Enable by default support for large devices and files (CONFIG_LBD):

- With 1TB disks being a commodity hardware it is quite easy to hit 2TB
  limitation while building RAIDs etc. and many distros have been using
  CONFIG_LBD=y by default already (at least Fedora 10 and openSUSE 11.1).

- This should also prevent a subtle ext4 filesystem compatibility issue:
  mke2fs.ext4 defaults to creating filesystems with huge_files feature
  enabled and such filesystems cannot be later mounted read-write on
  machines with CONFIG_LBD=n (it should be quite easy to hit this issue
  when trying to use filesystem created using distro kernel on system
  running the self-build kernel, think about USB disk enclosures & co.).

While at it:

- Clarify config option help text w.r.t. mounting ext4 filesystems
  (they can be mounted with CONFIG_LBD=n but in the read-only mode).

Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

parent 586cf268

block/Kconfig

+7 −4

Original line number	Diff line number	Diff line
		@@ -26,6 +26,7 @@ if BLOCK
		config LBD
		bool "Support for large block devices and files"
		depends on !64BIT
		default y
		help
		Enable block devices or files of size 2TB and larger.

		@@ -38,11 +39,13 @@ config LBD

		The ext4 filesystem requires that this feature be enabled in
		order to support filesystems that have the huge_file feature
		enabled. Otherwise, it will refuse to mount any filesystems
		that use the huge_file feature, which is enabled by default
		by mke2fs.ext4. The GFS2 filesystem also requires this feature.
		enabled. Otherwise, it will refuse to mount in the read-write
		mode any filesystems that use the huge_file feature, which is
		enabled by default by mke2fs.ext4.

		If unsure, say N.
		The GFS2 filesystem also requires this feature.

		If unsure, say Y.

		config BLK_DEV_BSG
		bool "Block layer SG support v4 (EXPERIMENTAL)"