Messages in this thread | | | Date | Thu, 26 Feb 2004 16:10:26 +0100 | From | Jens Axboe <> | Subject | Re: [PATCH] fix small highmem bio bounce bvec handling glitch |
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On Thu, Feb 26 2004, Christophe Saout wrote: > Hi, > > [Oops, forgot to Cc LKML] > > while going through the bio highmem handling code I noticed a small > glitch. __end_that_request_first might modify the bv_offset and bv_len > if the segment was partially completed. The bio-read-bounce-back code > should use the unmodified bv_offset when copying the segment data: > > --- linux.orig/mm/highmem.c 2004-01-21 19:08:45.000000000 +0100 > +++ linux/mm/highmem.c 2004-02-26 15:47:14.574722576 +0100 > @@ -294,7 +294,12 @@ > if (tovec->bv_page == fromvec->bv_page) > continue; > > - vfrom = page_address(fromvec->bv_page) + fromvec->bv_offset; > + /* > + * fromvec->bv_offset and fromvec->bv_len might have been > + * modified by the block layer, so use the original copy, > + * bounce_copy_vec already uses tovec->bv_len > + */ > + vfrom = page_address(fromvec->bv_page) + tovec->bv_offset; > > bounce_copy_vec(tovec, vfrom);
Irk yes, that's is pretty nasty, I really wish we could avoid screwing with vec entries (it's pretty obscure for bio clones, too)... Fix is correct, and good idea to add the comment!
-- Jens Axboe
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