Messages in this thread Patch in this message | | | From | Bartlomiej Zolnierkiewicz <> | Subject | [RFC][PATCH] block: enable by default support for large devices and files on 32-bit archs | Date | Sat, 28 Mar 2009 19:16:06 +0100 |
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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> --- Unfortunately to also update the existings [def]configs the config option rename would be needed. Actually, since the performance impact and kernel size increase seem to be minimal (at least on x86-32) maybe we should just go ahead and remove CONFIG_LBD (== always use 64-bit sector_t/blkcnt_t)?
I can make needed changes once there is agreement on preferred approach...
block/Kconfig | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
Index: b/block/Kconfig =================================================================== --- a/block/Kconfig +++ b/block/Kconfig @@ -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_IO_TRACE bool "Support for tracing block io actions"
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