Re: [PATCH] REQ-flags to/from BIO-flags bugfix

Matthew Wilcox
2007-12-12T15:54:29Z

On Wed, Dec 12, 2007 at 08:18:14AM -0700, Matthew Wilcox wrote:
> I don't know whether BIO_RW_BARRIER is __REQ_SOFTBARRIER or
> __REQ_HARDBARRIER, so I didn't include that in this patch. There also
> doesn't seem to be a __REQ equivalent to BIO_RW_AHEAD, but we can do
> the other four bits (and leave gaps for those two).

Hm. BIO_RW_AHEAD seems unused:

willy@honeydew:~/kernel/linux-2.6$ grep -r BIO_RW_AHEAD *
block/blktrace.c: (((rw) & (1 << BIO_RW_AHEAD)) << (2 - BIO_RW_AHEAD))
include/linux/bio.h:#define BIO_RW_AHEAD 1
include/linux/bio.h:#define bio_rw_ahead(bio) ((bio)->bi_rw & (1 << BIO_RW_AHEAD))
willy@honeydew:~/kernel/linux-2.6$ grep -r bio_rw_ahead *
block/ll_rw_blk.c: if (bio_rw_ahead(bio) || bio_failfast(bio))
drivers/md/dm-mpath.c: if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
drivers/md/multipath.c: else if (!bio_rw_ahead(bio)) {
include/linux/bio.h:#define bio_rw_ahead(bio) ((bio)->bi_rw & (1 << BIO_RW_AHEAD))

BIO_RW_BARRIER seems to be __REQ_HARDBARRIER, but we set it
explicitly in init_request_from_bio(). We could probably simplify
init_request_from_bio() with the patch in the previous message.

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