Messages in this thread | | | Subject | Re: LVM on md0: raid0_make_request bug: can't convert block across chunks or bigger than 64k | From | Karl Vogel <> | Date | Tue, 21 Oct 2003 18:29:20 +0200 |
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On Tue, 2003-10-21 at 15:41, Kevin Corry wrote: > On Monday 20 October 2003 19:09, Neil Brown wrote: > > On Monday October 20, karl.vogel@seagha.com wrote: > > > On Mon, 2003-10-20 at 23:06, Kevin Corry wrote: > > > > On Monday 20 October 2003 15:35, Karl Vogel wrote: > > > > > I'm getting the following kernel messages on V2.6.0-test8-mm1 (I've > > > > > also tried plain -test7 and some kernels before that) when copying > > > > > moderately sized files from a raid-0/LVM volume: > > > > > > > > > > --- snip --- > > > > > raid0_make_request bug: can't convert block across chunks or bigger > > > > > than 64k 24081064 64 > > > > > raid0_make_request bug: can't convert block across chunks or bigger > > > > > than 64k 24080656 64 > > > > > raid0_make_request bug: can't convert block across chunks or bigger > > > > > than 64k 24080784 64 > > > > > raid0_make_request bug: can't convert block across chunks or bigger > > > > > than 64k 24080928 64 > > > > > > > > Looks like this was just recently fixed on the linux-raid list. > > > > > > > > http://marc.theaimsgroup.com/?l=linux-raid&m=106661294929434 > > > > > > Applied the patch on 2.6.0-test8-mm1 but it made no difference. > > > > no, thats a completely different problem. > > Sorry for the confusion. Karl's error messages looked just like ones that were > reported on the evms-devel list, which were supposedly fixed by the above > patch. > > > The problem is that dm is not honouring the merge_bvec_fn that > > raid0 has set. > > > > This patch might fix it, but I'm not very familiar with the dm code, > > so I make no promises. > > > > ----------- Diffstat output ------------ > > ./drivers/md/dm-table.c | 5 +++++ > > 1 files changed, 5 insertions(+) > > > > diff ./drivers/md/dm-table.c~current~ ./drivers/md/dm-table.c > > --- ./drivers/md/dm-table.c~current~ 2003-10-21 10:05:29.000000000 +1000 > > +++ ./drivers/md/dm-table.c 2003-10-21 10:06:27.000000000 +1000 > > @@ -489,6 +489,11 @@ int dm_get_device(struct dm_target *ti, > > rs->max_sectors = > > min_not_zero(rs->max_sectors, q->max_sectors); > > > > + if (q->merge_bvec_fn) > > + rs->max_sectors = > > + min_not_zero(rs->max_sectors, PAGE_SIZE>>9); > > + > > + > > rs->max_phys_segments = > > min_not_zero(rs->max_phys_segments, > > q->max_phys_segments); > > This will probably work, as long as raid0 can split a one-page request that > spans a chunk boundary. I'll be interested to see if this solves Karl's > problem.
Good news... it solves the problem with my setup. I was able to copy files off the logical volume (did an md5sum compare to make sure I got the complete files.)
> Joe Thornber was telling me about an idea he had to solve the > Device-Mapper-on-top-of-MD problem using the dm-io code in his latest > Device-Mapper patchset > (http://people.sistina.com/~thornber/patches/2.6/2.6.0-test6/2.6.0-t6-mm1-dm2.tar.bz2). > I believe he's away for this week, but I'll ask him about it again the next > time I talk to him.
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