Re: bcache on XFS: metadata I/O (dirent I/O?) not getting cached at all?

From: Andre Noll
Date: Wed Feb 06 2019 - 19:53:58 EST


On Thu, Feb 07, 10:43, Dave Chinner wrote
> File data readahead: REQ_RAHEAD
> Metadata readahead: REQ_META | REQ_RAHEAD
>
> drivers/md/bcache/request.c::check_should_bypass():
>
> /*
> * Flag for bypass if the IO is for read-ahead or background,
> * unless the read-ahead request is for metadata (eg, for gfs2).
> */
> if (bio->bi_opf & (REQ_RAHEAD|REQ_BACKGROUND) &&
> !(bio->bi_opf & REQ_PRIO))
> goto skip;
>
> bcache needs fixing - it thinks REQ_PRIO means metadata IO. That's
> wrong - REQ_META means it's metadata IO, and so this is a bcache
> bug.

Do you think 752f66a75abad is bad (ha!) and should be reverted?

Thanks
Andre
--
Max Planck Institute for Developmental Biology
Max-Planck-Ring 5, 72076 TÃbingen, Germany. Phone: (+49) 7071 601 829
http://people.tuebingen.mpg.de/maan/

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