Messages in this thread | | | Date | Tue, 21 Apr 2009 09:25:24 +0200 | From | Jens Axboe <> | Subject | Re: [RFC][PATCH] block: enable by default support for large devices and files on 32-bit archs |
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On Mon, Apr 20 2009, Bartlomiej Zolnierkiewicz wrote: > On Saturday 28 March 2009 19:16:06 Bartlomiej Zolnierkiewicz wrote: > > > > 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... > > Jens, any thoughts on this? > > [ Please note that the patch below should be safe for 2.6.30. ]
I'm fine with it, and since nobody has objected since it was posted, lets just do it. I have added it.
> > > 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" > >
-- Jens Axboe
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