Multiple block drivers use zero_fill_bio() to zero-initialize the data buffer used for read operations. Make sure that all pages are zeroed instead of only the first if one or more multi-page bvecs are used to describe the data buffer.
Cc: Christoph Hellwig hch@lst.de Cc: Ming Lei ming.lei@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Bart Van Assche bvanassche@acm.org --- block/bio.c | 27 ++++++++++++++++++++++----- include/linux/bio.h | 1 + 2 files changed, 23 insertions(+), 5 deletions(-)
diff --git a/block/bio.c b/block/bio.c index 1594804fe8bc..48fcafbdae70 100644 --- a/block/bio.c +++ b/block/bio.c @@ -527,17 +527,34 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs, } EXPORT_SYMBOL(bio_alloc_bioset);
+void zero_fill_bvec(const struct bio_vec *bvec) +{ + struct page *page = bvec->bv_page; + u32 offset = bvec->bv_offset; + u32 left = bvec->bv_len; + + while (left) { + u32 len = min_t(u32, left, PAGE_SIZE - offset); + void *kaddr; + + kaddr = kmap_atomic(page); + memset(kaddr + offset, 0, len); + flush_dcache_page(page); + kunmap_atomic(kaddr); + page++; + left -= len; + offset = 0; + } +} +EXPORT_SYMBOL(zero_fill_bvec); + void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start) { - unsigned long flags; struct bio_vec bv; struct bvec_iter iter;
__bio_for_each_segment(bv, bio, iter, start) { - char *data = bvec_kmap_irq(&bv, &flags); - memset(data, 0, bv.bv_len); - flush_dcache_page(bv.bv_page); - bvec_kunmap_irq(data, &flags); + zero_fill_bvec(&bv); } } EXPORT_SYMBOL(zero_fill_bio_iter); diff --git a/include/linux/bio.h b/include/linux/bio.h index 58e6134b1c05..9438cbdfa19e 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -455,6 +455,7 @@ extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter, extern void bio_copy_data(struct bio *dst, struct bio *src); extern void bio_list_copy_data(struct bio *dst, struct bio *src); extern void bio_free_pages(struct bio *bio); +void zero_fill_bvec(const struct bio_vec *bvec); void zero_fill_bio_iter(struct bio *bio, struct bvec_iter iter); void bio_truncate(struct bio *bio, unsigned new_size); void guard_bio_eod(struct bio *bio);