[PATCH 01/23] block: factor out a bvec_set_page helper

[Matthew Wilcox]

On Tue, Jan 31, 2023 at 05:00:32AM +0000, Matthew Wilcox wrote:
> On Mon, Jan 30, 2023 at 08:47:58PM -0800, Jakub Kicinski wrote:
> > kinda random thought but since we're touching this area - could we
> > perhaps move the definition of struct bio_vec and trivial helpers 
> > like this into a new header? bvec.h pulls in mm.h which is a right
> > behemoth :S
> 
> I bet we can drop mm.h now.  It was originally added for nth_page()
> in 3d75ca0adef4 but those were all removed by b8753433fc61.
> 
> A quick smoke test on my default testing config doesn't find any
> problems.  Let me send a patch and see if the build bots complain.

Disappointingly, it doesn't really change anything.  1134 files
depend on mm.h both before and after [1].  Looks like it's due to
arch/x86/include/asm/cacheflush.h pulling in linux/mm.h, judging by the
contents of .build_test_kernel-x86_64/net/ipv6/.inet6_hashtables.o.cmd.
But *lots* of header files pull in mm.h, including scatterlist.h,
vt_kern.h, net.h, nfs_fs.h, sunrpc/svc.h and security.h.

I suppose it may cut down on include loops to drop it here, so I'm
still in favour of the patch I posted, but this illustrates how
deeply entangled our headers still are.

[1] find .build_test_kernel-x86_64/ -name '.*.cmd' |xargs grep 'include/linux/mm.h' |wc -l