/* bounce buffer handling for block devices * * - Split from highmem.c */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/mm.h>#include <linux/export.h>#include <linux/swap.h>#include <linux/gfp.h>#include <linux/bio.h>#include <linux/pagemap.h>#include <linux/mempool.h>#include <linux/blkdev.h>#include <linux/backing-dev.h>#include <linux/init.h>#include <linux/hash.h>#include <linux/highmem.h>#include <linux/bootmem.h>#include <linux/printk.h>#include <asm/tlbflush.h> #include <trace/events/block.h> #define POOL_SIZE	64#define ISA_POOL_SIZE	16 static mempool_t *page_pool, *isa_page_pool; #if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL)static __init int init_emergency_pool(void){#if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG)	if (max_pfn <= max_low_pfn)		return 0;#endif 	page_pool = mempool_create_page_pool(POOL_SIZE, 0);	BUG_ON(!page_pool);	pr_info("pool size: %d pages\n", POOL_SIZE); 	return 0;} __initcall(init_emergency_pool);#endif #ifdef CONFIG_HIGHMEM/* * highmem version, map in to vec */static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom){	unsigned long flags;	unsigned char *vto; 	local_irq_save(flags);	vto = kmap_atomic(to->bv_page);	memcpy(vto + to->bv_offset, vfrom, to->bv_len);	kunmap_atomic(vto);	local_irq_restore(flags);} #else /* CONFIG_HIGHMEM */ #define bounce_copy_vec(to, vfrom)	\	memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) #endif /* CONFIG_HIGHMEM */ /* * allocate pages in the DMA region for the ISA pool */static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data){	return mempool_alloc_pages(gfp_mask | GFP_DMA, data);} /* * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA * as the max address, so check if the pool has already been created. */int init_emergency_isa_pool(void){	if (isa_page_pool)		return 0; 	isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,				       mempool_free_pages, (void *) 0);	BUG_ON(!isa_page_pool); 	pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE);	return 0;} /* * Simple bounce buffer support for highmem pages. Depending on the * queue gfp mask set, *to may or may not be a highmem page. kmap it * always, it will do the Right Thing */static void copy_to_high_bio_irq(struct bio *to, struct bio *from){	unsigned char *vfrom;	struct bio_vec tovec, *fromvec = from->bi_io_vec;	struct bvec_iter iter; 	bio_for_each_segment(tovec, to, iter) {		if (tovec.bv_page != fromvec->bv_page) {			/*			 * fromvec->bv_offset and fromvec->bv_len might have			 * been modified by the block layer, so use the original			 * copy, bounce_copy_vec already uses tovec->bv_len			 */			vfrom = page_address(fromvec->bv_page) +				tovec.bv_offset; 			bounce_copy_vec(&tovec, vfrom);			flush_dcache_page(tovec.bv_page);		} 		fromvec++;	}} static void bounce_end_io(struct bio *bio, mempool_t *pool, int err){	struct bio *bio_orig = bio->bi_private;	struct bio_vec *bvec, *org_vec;	int i; 	/*	 * free up bounce indirect pages used	 */	bio_for_each_segment_all(bvec, bio, i) {		org_vec = bio_orig->bi_io_vec + i;		if (bvec->bv_page == org_vec->bv_page)			continue; 		dec_zone_page_state(bvec->bv_page, NR_BOUNCE);		mempool_free(bvec->bv_page, pool);	} 	bio_endio(bio_orig, err);	bio_put(bio);} static void bounce_end_io_write(struct bio *bio, int err){	bounce_end_io(bio, page_pool, err);} static void bounce_end_io_write_isa(struct bio *bio, int err){ 	bounce_end_io(bio, isa_page_pool, err);} static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err){	struct bio *bio_orig = bio->bi_private; 	if (test_bit(BIO_UPTODATE, &bio->bi_flags))		copy_to_high_bio_irq(bio_orig, bio); 	bounce_end_io(bio, pool, err);} static void bounce_end_io_read(struct bio *bio, int err){	__bounce_end_io_read(bio, page_pool, err);} static void bounce_end_io_read_isa(struct bio *bio, int err){	__bounce_end_io_read(bio, isa_page_pool, err);} #ifdef CONFIG_NEED_BOUNCE_POOLstatic int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio){	if (bio_data_dir(bio) != WRITE)		return 0; 	if (!bdi_cap_stable_pages_required(&q->backing_dev_info))		return 0; 	return test_bit(BIO_SNAP_STABLE, &bio->bi_flags);}#elsestatic int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio){	return 0;}#endif /* CONFIG_NEED_BOUNCE_POOL */ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,			       mempool_t *pool, int force){	struct bio *bio;	int rw = bio_data_dir(*bio_orig);	struct bio_vec *to, from;	struct bvec_iter iter;	unsigned i; 	if (force)		goto bounce;	bio_for_each_segment(from, *bio_orig, iter)		if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q))			goto bounce; 	return;bounce:	bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set); 	bio_for_each_segment_all(to, bio, i) {		struct page *page = to->bv_page; 		if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)			continue; 		to->bv_page = mempool_alloc(pool, q->bounce_gfp);		inc_zone_page_state(to->bv_page, NR_BOUNCE); 		if (rw == WRITE) {			char *vto, *vfrom; 			flush_dcache_page(page); 			vto = page_address(to->bv_page) + to->bv_offset;			vfrom = kmap_atomic(page) + to->bv_offset;			memcpy(vto, vfrom, to->bv_len);			kunmap_atomic(vfrom);		}	} 	trace_block_bio_bounce(q, *bio_orig); 	bio->bi_flags |= (1 << BIO_BOUNCED); 	if (pool == page_pool) {		bio->bi_end_io = bounce_end_io_write;		if (rw == READ)			bio->bi_end_io = bounce_end_io_read;	} else {		bio->bi_end_io = bounce_end_io_write_isa;		if (rw == READ)			bio->bi_end_io = bounce_end_io_read_isa;	} 	bio->bi_private = *bio_orig;	*bio_orig = bio;} void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig){	int must_bounce;	mempool_t *pool; 	/*	 * Data-less bio, nothing to bounce	 */	if (!bio_has_data(*bio_orig))		return; 	must_bounce = must_snapshot_stable_pages(q, *bio_orig); 	/*	 * for non-isa bounce case, just check if the bounce pfn is equal	 * to or bigger than the highest pfn in the system -- in that case,	 * don't waste time iterating over bio segments	 */	if (!(q->bounce_gfp & GFP_DMA)) {		if (queue_bounce_pfn(q) >= blk_max_pfn && !must_bounce)			return;		pool = page_pool;	} else {		BUG_ON(!isa_page_pool);		pool = isa_page_pool;	} 	/*	 * slow path	 */	__blk_queue_bounce(q, bio_orig, pool, must_bounce);} EXPORT_SYMBOL(blk_queue_bounce);