Messages in this thread | | | From | Kevin Corry <> | Subject | Re: LVM on md0: raid0_make_request bug: can't convert block across chunks or bigger than 64k | Date | Tue, 21 Oct 2003 08:41:45 -0500 |
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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.
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.
-- Kevin Corry kevcorry@us.ibm.com http://evms.sourceforge.net/
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