[PATCH] fs/bio.c: tweaks (bf02c082) · Commits · 戴 / test

- Calculate a variable in bvec_alloc_bs() only once needed, not earlier (bio.o down from 18408 to 18376 Bytes, 32 Bytes saved, probably due to data locality improvements). - Init variable idx to silence a gcc warning which already existed in the unmodified original base file (bvec_alloc_bs() handles idx correctly, so there's no need for the warning): fs/bio.c: In function `bio_alloc_bioset': fs/bio.c:169: warning: `idx' may be used uninitialized in this function Signed-off-by:

Andreas Mohr <andi@lisas.de> Acked-by:

Jens Axboe <axboe@kernel.dk> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

fs/bio.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -79,7 +79,6 @@ static struct bio_set *fs_bio_set;
		static inline struct bio_vec bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long idx, struct bio_set *bs)
		{
		struct bio_vec *bvl;
		struct biovec_slab *bp;

		/*
		* see comment near bvec_array define!
		@@ -98,10 +97,12 @@ static inline struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned lon
		* idx now points to the pool we want to allocate from
		*/

		bp = bvec_slabs + *idx;
		bvl = mempool_alloc(bs->bvec_pools[*idx], gfp_mask);
		if (bvl)
		if (bvl) {
		struct biovec_slab bp = bvec_slabs + idx;

		memset(bvl, 0, bp->nr_vecs * sizeof(struct bio_vec));
		}

		return bvl;
		}
		@@ -166,7 +167,7 @@ struct bio bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set bs)

		bio_init(bio);
		if (likely(nr_iovecs)) {
		unsigned long idx;
		unsigned long idx = 0; /* shut up gcc */

		bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
		if (unlikely(!bvl)) {

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