/* bounce buffer handling for block devices * * - Split from highmem.c */#include <linux/mm.h>#include <linux/module.h>#include <linux/swap.h>#include <linux/bio.h>#include <linux/pagemap.h>#include <linux/mempool.h>#include <linux/blkdev.h>#include <linux/init.h>#include <linux/hash.h>#include <linux/highmem.h>#include <linux/blktrace_api.h>#include <trace/block.h>#include <asm/tlbflush.h>#define POOL_SIZE	64#define ISA_POOL_SIZE	16static mempool_t *page_pool, *isa_page_pool;DEFINE_TRACE(block_bio_bounce);#ifdef CONFIG_HIGHMEMstatic __init int init_emergency_pool(void){	struct sysinfo i;	si_meminfo(&i);	si_swapinfo(&i);	if (!i.totalhigh)		return 0;	page_pool = mempool_create_page_pool(POOL_SIZE, 0);	BUG_ON(!page_pool);	printk("highmem bounce pool size: %d pages\n", POOL_SIZE);	return 0;}__initcall(init_emergency_pool);/* * 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, KM_BOUNCE_READ);	memcpy(vto + to->bv_offset, vfrom, to->bv_len);	kunmap_atomic(vto, KM_BOUNCE_READ);	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);	printk("isa bounce 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;	int i;	__bio_for_each_segment(tovec, to, i, 0) {		fromvec = from->bi_io_vec + i;		/*		 * not bounced		 */		if (tovec->bv_page == fromvec->bv_page)			continue;		/*		 * 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;		flush_dcache_page(tovec->bv_page);		bounce_copy_vec(tovec, vfrom);	}}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;	if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))		set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);	/*	 * free up bounce indirect pages used	 */	__bio_for_each_segment(bvec, bio, i, 0) {		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);}static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,			       mempool_t *pool){	struct page *page;	struct bio *bio = NULL;	int i, rw = bio_data_dir(*bio_orig);	struct bio_vec *to, *from;	bio_for_each_segment(from, *bio_orig, i) {		page = from->bv_page;		/*		 * is destination page below bounce pfn?		 */		if (page_to_pfn(page) <= q->bounce_pfn)			continue;		/*		 * irk, bounce it		 */		if (!bio) {			unsigned int cnt = (*bio_orig)->bi_vcnt;			bio = bio_alloc(GFP_NOIO, cnt);			memset(bio->bi_io_vec, 0, cnt * sizeof(struct bio_vec));		}					to = bio->bi_io_vec + i;		to->bv_page = mempool_alloc(pool, q->bounce_gfp);		to->bv_len = from->bv_len;		to->bv_offset = from->bv_offset;		inc_zone_page_state(to->bv_page, NR_BOUNCE);		if (rw == WRITE) {			char *vto, *vfrom;			flush_dcache_page(from->bv_page);			vto = page_address(to->bv_page) + to->bv_offset;			vfrom = kmap(from->bv_page) + from->bv_offset;			memcpy(vto, vfrom, to->bv_len);			kunmap(from->bv_page);		}	}	/*	 * no pages bounced	 */	if (!bio)		return;	trace_block_bio_bounce(q, *bio_orig);	/*	 * at least one page was bounced, fill in possible non-highmem	 * pages	 */	__bio_for_each_segment(from, *bio_orig, i, 0) {		to = bio_iovec_idx(bio, i);		if (!to->bv_page) {			to->bv_page = from->bv_page;			to->bv_len = from->bv_len;			to->bv_offset = from->bv_offset;		}	}	bio->bi_bdev = (*bio_orig)->bi_bdev;	bio->bi_flags |= (1 << BIO_BOUNCED);	bio->bi_sector = (*bio_orig)->bi_sector;	bio->bi_rw = (*bio_orig)->bi_rw;	bio->bi_vcnt = (*bio_orig)->bi_vcnt;	bio->bi_idx = (*bio_orig)->bi_idx;	bio->bi_size = (*bio_orig)->bi_size;	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->bounce_pfn >= blk_max_pfn)			return;		pool = page_pool;	} else {		BUG_ON(!isa_page_pool);		pool = isa_page_pool;	}	/*	 * slow path	 */	__blk_queue_bounce(q, bio_orig, pool);}EXPORT_SYMBOL(blk_queue_bounce);