Messages in this thread | | | Date | Mon, 25 Mar 2013 10:28:38 +0000 | From | Joe Thornber <> | Subject | Re: [PATCH] dm: dm-cache fails to write the cache device in writethrough mode |
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Hi Darrick,
On Fri, Mar 22, 2013 at 01:11:51PM -0700, Darrick J. Wong wrote: > The new writethrough strategy for dm-cache issues a bio to the origin device, > remaps the bio to the cache device, and issues the bio to the cache device. > However, the block layer modifies bi_sector and bi_size, so we need to preserve > these or else nothing gets written to the cache (bi_size == 0). This fixes the > problem where someone writes a block through the cache, but a subsequent reread > (from the cache) returns old contents.
Thanks for diagnosing this, as you may have gathered none of the hardware we're testing on does this. I've pushed a patch to dm-devel that hopefully will make it's way upstream very quickly. I used dm_bio_record/restore, since there are many more fields that underlying drivers make tweak in the bio.
- Joe
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