From: Andreas Mohr - 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 Cc: Jens Axboe Signed-off-by: Andrew Morton --- fs/bio.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff -puN fs/bio.c~fs-bioc-tweaks fs/bio.c --- a/fs/bio.c~fs-bioc-tweaks +++ a/fs/bio.c @@ -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 * 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_m 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)) { _