Re: [PATCH 07/15] blkcg: consolidate bio_issue_init and blkg association

[kbuild test robot]

Hi Dennis,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on block/for-next]
[also build test ERROR on v4.19-rc1 next-20180831]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dennis-Zhou/blkcg-ref-count-refactor-cleanup-blkcg-avg_lat/20180831-161742
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
config: i386-randconfig-a0-201834 (attached as .config)
compiler: gcc-4.9 (Debian 4.9.4-2) 4.9.4
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   In file included from block/bounce.c:13:0:
   include/linux/bio.h:566:17: warning: 'struct blkcg_gq' declared inside parameter list
             struct blkcg_gq *blkg) { return 0; }
                    ^
   include/linux/bio.h:566:17: warning: its scope is only this definition or declaration, which is probably not what you want
   block/bounce.c: In function 'bounce_clone_bio':
>> block/bounce.c:262:21: error: 'struct bio' has no member named 'bi_issue'
     bio_issue_init(&bio->bi_issue, bio_sectors(bio));
                        ^

vim +262 block/bounce.c

   197	
   198	static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,
   199			struct bio_set *bs)
   200	{
   201		struct bvec_iter iter;
   202		struct bio_vec bv;
   203		struct bio *bio;
   204	
   205		/*
   206		 * Pre immutable biovecs, __bio_clone() used to just do a memcpy from
   207		 * bio_src->bi_io_vec to bio->bi_io_vec.
   208		 *
   209		 * We can't do that anymore, because:
   210		 *
   211		 *  - The point of cloning the biovec is to produce a bio with a biovec
   212		 *    the caller can modify: bi_idx and bi_bvec_done should be 0.
   213		 *
   214		 *  - The original bio could've had more than BIO_MAX_PAGES biovecs; if
   215		 *    we tried to clone the whole thing bio_alloc_bioset() would fail.
   216		 *    But the clone should succeed as long as the number of biovecs we
   217		 *    actually need to allocate is fewer than BIO_MAX_PAGES.
   218		 *
   219		 *  - Lastly, bi_vcnt should not be looked at or relied upon by code
   220		 *    that does not own the bio - reason being drivers don't use it for
   221		 *    iterating over the biovec anymore, so expecting it to be kept up
   222		 *    to date (i.e. for clones that share the parent biovec) is just
   223		 *    asking for trouble and would force extra work on
   224		 *    __bio_clone_fast() anyways.
   225		 */
   226	
   227		bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
   228		if (!bio)
   229			return NULL;
   230		bio->bi_disk		= bio_src->bi_disk;
   231		bio->bi_opf		= bio_src->bi_opf;
   232		bio->bi_write_hint	= bio_src->bi_write_hint;
   233		bio->bi_iter.bi_sector	= bio_src->bi_iter.bi_sector;
   234		bio->bi_iter.bi_size	= bio_src->bi_iter.bi_size;
   235	
   236		switch (bio_op(bio)) {
   237		case REQ_OP_DISCARD:
   238		case REQ_OP_SECURE_ERASE:
   239		case REQ_OP_WRITE_ZEROES:
   240			break;
   241		case REQ_OP_WRITE_SAME:
   242			bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
   243			break;
   244		default:
   245			bio_for_each_segment(bv, bio_src, iter)
   246				bio->bi_io_vec[bio->bi_vcnt++] = bv;
   247			break;
   248		}
   249	
   250		if (bio_integrity(bio_src)) {
   251			int ret;
   252	
   253			ret = bio_integrity_clone(bio, bio_src, gfp_mask);
   254			if (ret < 0) {
   255				bio_put(bio);
   256				return NULL;
   257			}
   258		}
   259	
   260		bio_clone_blkcg_association(bio, bio_src);
   261	
 > 262		bio_issue_init(&bio->bi_issue, bio_sectors(bio));
   263	
   264		return bio;
   265	}
   266	

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