// SPDX-License-Identifier: GPL-2.0/* 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/memblock.h>#include <linux/printk.h>#include <asm/tlbflush.h> #include <trace/events/block.h>#include "blk.h" #define POOL_SIZE	64#define ISA_POOL_SIZE	16 static struct bio_set bounce_bio_set, bounce_bio_split;static mempool_t page_pool, isa_page_pool; static void init_bounce_bioset(void){	static bool bounce_bs_setup;	int ret; 	if (bounce_bs_setup)		return; 	ret = bioset_init(&bounce_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);	BUG_ON(ret);	if (bioset_integrity_create(&bounce_bio_set, BIO_POOL_SIZE))		BUG_ON(1); 	ret = bioset_init(&bounce_bio_split, BIO_POOL_SIZE, 0, 0);	BUG_ON(ret);	bounce_bs_setup = true;} #if defined(CONFIG_HIGHMEM)static __init int init_emergency_pool(void){	int ret;#if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG)	if (max_pfn <= max_low_pfn)		return 0;#endif 	ret = mempool_init_page_pool(&page_pool, POOL_SIZE, 0);	BUG_ON(ret);	pr_info("pool size: %d pages\n", POOL_SIZE); 	init_bounce_bioset();	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 char *vto; 	vto = kmap_atomic(to->bv_page);	memcpy(vto + to->bv_offset, vfrom, to->bv_len);	kunmap_atomic(vto);} #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);} static DEFINE_MUTEX(isa_mutex); /* * 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){	int ret; 	mutex_lock(&isa_mutex); 	if (mempool_initialized(&isa_page_pool)) {		mutex_unlock(&isa_mutex);		return 0;	} 	ret = mempool_init(&isa_page_pool, ISA_POOL_SIZE, mempool_alloc_pages_isa,			   mempool_free_pages, (void *) 0);	BUG_ON(ret); 	pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE);	init_bounce_bioset();	mutex_unlock(&isa_mutex);	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;	struct bvec_iter iter;	/*	 * The bio of @from is created by bounce, so we can iterate	 * its bvec from start to end, but the @from->bi_iter can't be	 * trusted because it might be changed by splitting.	 */	struct bvec_iter from_iter = BVEC_ITER_ALL_INIT; 	bio_for_each_segment(tovec, to, iter) {		fromvec = bio_iter_iovec(from, from_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);		}		bio_advance_iter(from, &from_iter, tovec.bv_len);	}} static void bounce_end_io(struct bio *bio, mempool_t *pool){	struct bio *bio_orig = bio->bi_private;	struct bio_vec *bvec, orig_vec;	struct bvec_iter orig_iter = bio_orig->bi_iter;	struct bvec_iter_all iter_all; 	/*	 * free up bounce indirect pages used	 */	bio_for_each_segment_all(bvec, bio, iter_all) {		orig_vec = bio_iter_iovec(bio_orig, orig_iter);		if (bvec->bv_page != orig_vec.bv_page) {			dec_zone_page_state(bvec->bv_page, NR_BOUNCE);			mempool_free(bvec->bv_page, pool);		}		bio_advance_iter(bio_orig, &orig_iter, orig_vec.bv_len);	} 	bio_orig->bi_status = bio->bi_status;	bio_endio(bio_orig);	bio_put(bio);} static void bounce_end_io_write(struct bio *bio){	bounce_end_io(bio, &page_pool);} static void bounce_end_io_write_isa(struct bio *bio){ 	bounce_end_io(bio, &isa_page_pool);} static void __bounce_end_io_read(struct bio *bio, mempool_t *pool){	struct bio *bio_orig = bio->bi_private; 	if (!bio->bi_status)		copy_to_high_bio_irq(bio_orig, bio); 	bounce_end_io(bio, pool);} static void bounce_end_io_read(struct bio *bio){	__bounce_end_io_read(bio, &page_pool);} static void bounce_end_io_read_isa(struct bio *bio){	__bounce_end_io_read(bio, &isa_page_pool);} static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,		struct bio_set *bs){	struct bvec_iter iter;	struct bio_vec bv;	struct bio *bio; 	/*	 * Pre immutable biovecs, __bio_clone() used to just do a memcpy from	 * bio_src->bi_io_vec to bio->bi_io_vec.	 *	 * We can't do that anymore, because:	 *	 *  - The point of cloning the biovec is to produce a bio with a biovec	 *    the caller can modify: bi_idx and bi_bvec_done should be 0.	 *	 *  - The original bio could've had more than BIO_MAX_PAGES biovecs; if	 *    we tried to clone the whole thing bio_alloc_bioset() would fail.	 *    But the clone should succeed as long as the number of biovecs we	 *    actually need to allocate is fewer than BIO_MAX_PAGES.	 *	 *  - Lastly, bi_vcnt should not be looked at or relied upon by code	 *    that does not own the bio - reason being drivers don't use it for	 *    iterating over the biovec anymore, so expecting it to be kept up	 *    to date (i.e. for clones that share the parent biovec) is just	 *    asking for trouble and would force extra work on	 *    __bio_clone_fast() anyways.	 */ 	bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);	if (!bio)		return NULL;	bio->bi_disk		= bio_src->bi_disk;	bio->bi_opf		= bio_src->bi_opf;	bio->bi_ioprio		= bio_src->bi_ioprio;	bio->bi_write_hint	= bio_src->bi_write_hint;	bio->bi_iter.bi_sector	= bio_src->bi_iter.bi_sector;	bio->bi_iter.bi_size	= bio_src->bi_iter.bi_size; 	switch (bio_op(bio)) {	case REQ_OP_DISCARD:	case REQ_OP_SECURE_ERASE:	case REQ_OP_WRITE_ZEROES:		break;	case REQ_OP_WRITE_SAME:		bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];		break;	default:		bio_for_each_segment(bv, bio_src, iter)			bio->bi_io_vec[bio->bi_vcnt++] = bv;		break;	} 	bio_crypt_clone(bio, bio_src, gfp_mask); 	if (bio_integrity(bio_src)) {		int ret; 		ret = bio_integrity_clone(bio, bio_src, gfp_mask);		if (ret < 0) {			bio_put(bio);			return NULL;		}	} 	bio_clone_blkg_association(bio, bio_src);	blkcg_bio_issue_init(bio); 	return bio;} static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,			       mempool_t *pool){	struct bio *bio;	int rw = bio_data_dir(*bio_orig);	struct bio_vec *to, from;	struct bvec_iter iter;	unsigned i = 0;	bool bounce = false;	int sectors = 0;	bool passthrough = bio_is_passthrough(*bio_orig); 	bio_for_each_segment(from, *bio_orig, iter) {		if (i++ < BIO_MAX_PAGES)			sectors += from.bv_len >> 9;		if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn)			bounce = true;	}	if (!bounce)		return; 	if (!passthrough && sectors < bio_sectors(*bio_orig)) {		bio = bio_split(*bio_orig, sectors, GFP_NOIO, &bounce_bio_split);		bio_chain(bio, *bio_orig);		submit_bio_noacct(*bio_orig);		*bio_orig = bio;	}	bio = bounce_clone_bio(*bio_orig, GFP_NOIO, passthrough ? NULL :			&bounce_bio_set); 	/*	 * Bvec table can't be updated by bio_for_each_segment_all(),	 * so retrieve bvec from the table directly. This way is safe	 * because the 'bio' is single-page bvec.	 */	for (i = 0, to = bio->bi_io_vec; i < bio->bi_vcnt; to++, i++) {		struct page *page = to->bv_page; 		if (page_to_pfn(page) <= q->limits.bounce_pfn)			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){	mempool_t *pool; 	/*	 * Data-less bio, nothing to bounce	 */	if (!bio_has_data(*bio_orig))		return; 	/*	 * 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 (q->limits.bounce_pfn >= blk_max_pfn)			return;		pool = &page_pool;	} else {		BUG_ON(!mempool_initialized(&isa_page_pool));		pool = &isa_page_pool;	} 	/*	 * slow path	 */	__blk_queue_bounce(q, bio_orig, pool);}