// 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-integrity.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/printk.h>#include <asm/tlbflush.h> #include <trace/events/block.h>#include "blk.h"#include "blk-cgroup.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; 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;} static __init int init_emergency_pool(void){	int ret; #ifndef 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); /* * 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){	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			 */			memcpy_to_bvec(&tovec, page_address(fromvec.bv_page) +				       tovec.bv_offset);		}		bio_advance_iter(from, &from_iter, tovec.bv_len);	}} static void bounce_end_io(struct bio *bio){	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, &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);} static void bounce_end_io_read(struct bio *bio){	struct bio *bio_orig = bio->bi_private; 	if (!bio->bi_status)		copy_to_high_bio_irq(bio_orig, bio); 	bounce_end_io(bio);} static struct bio *bounce_clone_bio(struct bio *bio_src){	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_VECS 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_VECS.	 *	 *  - 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.	 */	bio = bio_alloc_bioset(bio_src->bi_bdev, bio_segments(bio_src),			       bio_src->bi_opf, GFP_NOIO, &bounce_bio_set);	if (bio_flagged(bio_src, BIO_REMAPPED))		bio_set_flag(bio, BIO_REMAPPED);	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;	default:		bio_for_each_segment(bv, bio_src, iter)			bio->bi_io_vec[bio->bi_vcnt++] = bv;		break;	} 	if (bio_crypt_clone(bio, bio_src, GFP_NOIO) < 0)		goto err_put; 	if (bio_integrity(bio_src) &&	    bio_integrity_clone(bio, bio_src, GFP_NOIO) < 0)		goto err_put; 	bio_clone_blkg_association(bio, bio_src); 	return bio; err_put:	bio_put(bio);	return NULL;} struct bio *__blk_queue_bounce(struct bio *bio_orig, struct request_queue *q){	struct bio *bio;	int rw = bio_data_dir(bio_orig);	struct bio_vec *to, from;	struct bvec_iter iter;	unsigned i = 0, bytes = 0;	bool bounce = false;	int sectors; 	bio_for_each_segment(from, bio_orig, iter) {		if (i++ < BIO_MAX_VECS)			bytes += from.bv_len;		if (PageHighMem(from.bv_page))			bounce = true;	}	if (!bounce)		return bio_orig; 	/*	 * Individual bvecs might not be logical block aligned. Round down	 * the split size so that each bio is properly block size aligned,	 * even if we do not use the full hardware limits.	 */	sectors = ALIGN_DOWN(bytes, queue_logical_block_size(q)) >>			SECTOR_SHIFT;	if (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); 	/*	 * 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 *bounce_page; 		if (!PageHighMem(to->bv_page))			continue; 		bounce_page = mempool_alloc(&page_pool, GFP_NOIO);		inc_zone_page_state(bounce_page, NR_BOUNCE); 		if (rw == WRITE) {			flush_dcache_page(to->bv_page);			memcpy_from_bvec(page_address(bounce_page), to);		}		to->bv_page = bounce_page;	} 	trace_block_bio_bounce(bio_orig); 	bio->bi_flags |= (1 << BIO_BOUNCED); 	if (rw == READ)		bio->bi_end_io = bounce_end_io_read;	else		bio->bi_end_io = bounce_end_io_write; 	bio->bi_private = bio_orig;	return bio;}