1/* bounce buffer handling for block devices
  2 *
  3 * - Split from highmem.c
  4 */
  5
  6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  7
  8#include <linux/mm.h>
  9#include <linux/export.h>
 10#include <linux/swap.h>
 11#include <linux/gfp.h>
 12#include <linux/bio.h>
 13#include <linux/pagemap.h>
 14#include <linux/mempool.h>
 15#include <linux/blkdev.h>
 16#include <linux/backing-dev.h>
 17#include <linux/init.h>
 18#include <linux/hash.h>
 19#include <linux/highmem.h>
 20#include <linux/bootmem.h>
 21#include <linux/printk.h>
 22#include <asm/tlbflush.h>
 23
 24#include <trace/events/block.h>
 25
 26#define POOL_SIZE	64
 27#define ISA_POOL_SIZE	16
 28
 29static mempool_t *page_pool, *isa_page_pool;
 30
 31#if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL)
 32static __init int init_emergency_pool(void)
 33{
 34#if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG)
 35	if (max_pfn <= max_low_pfn)
 36		return 0;
 37#endif
 38
 39	page_pool = mempool_create_page_pool(POOL_SIZE, 0);
 40	BUG_ON(!page_pool);
 41	pr_info("pool size: %d pages\n", POOL_SIZE);
 42
 43	return 0;
 44}
 45
 46__initcall(init_emergency_pool);
 47#endif
 48
 49#ifdef CONFIG_HIGHMEM
 50/*
 51 * highmem version, map in to vec
 52 */
 53static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
 54{
 55	unsigned long flags;
 56	unsigned char *vto;
 57
 58	local_irq_save(flags);
 59	vto = kmap_atomic(to->bv_page);
 60	memcpy(vto + to->bv_offset, vfrom, to->bv_len);
 61	kunmap_atomic(vto);
 62	local_irq_restore(flags);
 63}
 64
 65#else /* CONFIG_HIGHMEM */
 66
 67#define bounce_copy_vec(to, vfrom)	\
 68	memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
 69
 70#endif /* CONFIG_HIGHMEM */
 71
 72/*
 73 * allocate pages in the DMA region for the ISA pool
 74 */
 75static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
 76{
 77	return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
 78}
 79
 80/*
 81 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
 82 * as the max address, so check if the pool has already been created.
 83 */
 84int init_emergency_isa_pool(void)
 85{
 86	if (isa_page_pool)
 87		return 0;
 88
 89	isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
 90				       mempool_free_pages, (void *) 0);
 91	BUG_ON(!isa_page_pool);
 92
 93	pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE);
 94	return 0;
 95}
 96
 97/*
 98 * Simple bounce buffer support for highmem pages. Depending on the
 99 * queue gfp mask set, *to may or may not be a highmem page. kmap it
100 * always, it will do the Right Thing
101 */
102static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
103{
104	unsigned char *vfrom;
105	struct bio_vec tovec, *fromvec = from->bi_io_vec;
106	struct bvec_iter iter;
107
108	bio_for_each_segment(tovec, to, iter) {
109		if (tovec.bv_page != fromvec->bv_page) {
110			/*
111			 * fromvec->bv_offset and fromvec->bv_len might have
112			 * been modified by the block layer, so use the original
113			 * copy, bounce_copy_vec already uses tovec->bv_len
114			 */
115			vfrom = page_address(fromvec->bv_page) +
116				tovec.bv_offset;
117
118			bounce_copy_vec(&tovec, vfrom);
119			flush_dcache_page(tovec.bv_page);
120		}
121
122		fromvec++;
123	}
124}
125
126static void bounce_end_io(struct bio *bio, mempool_t *pool)
127{
128	struct bio *bio_orig = bio->bi_private;
129	struct bio_vec *bvec, *org_vec;
130	int i;
131	int start = bio_orig->bi_iter.bi_idx;
132
133	/*
134	 * free up bounce indirect pages used
135	 */
136	bio_for_each_segment_all(bvec, bio, i) {
137		org_vec = bio_orig->bi_io_vec + i + start;
138
139		if (bvec->bv_page == org_vec->bv_page)
140			continue;
141
142		dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
143		mempool_free(bvec->bv_page, pool);
144	}
145
146	bio_orig->bi_error = bio->bi_error;
147	bio_endio(bio_orig);
148	bio_put(bio);
149}
150
151static void bounce_end_io_write(struct bio *bio)
152{
153	bounce_end_io(bio, page_pool);
154}
155
156static void bounce_end_io_write_isa(struct bio *bio)
157{
158
159	bounce_end_io(bio, isa_page_pool);
160}
161
162static void __bounce_end_io_read(struct bio *bio, mempool_t *pool)
163{
164	struct bio *bio_orig = bio->bi_private;
165
166	if (!bio->bi_error)
167		copy_to_high_bio_irq(bio_orig, bio);
168
169	bounce_end_io(bio, pool);
170}
171
172static void bounce_end_io_read(struct bio *bio)
173{
174	__bounce_end_io_read(bio, page_pool);
175}
176
177static void bounce_end_io_read_isa(struct bio *bio)
178{
179	__bounce_end_io_read(bio, isa_page_pool);
180}
181
182static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
183			       mempool_t *pool)
184{
185	struct bio *bio;
186	int rw = bio_data_dir(*bio_orig);
187	struct bio_vec *to, from;
188	struct bvec_iter iter;
189	unsigned i;
190
191	bio_for_each_segment(from, *bio_orig, iter)
192		if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q))
193			goto bounce;
194
195	return;
196bounce:
197	bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set);
198
199	bio_for_each_segment_all(to, bio, i) {
200		struct page *page = to->bv_page;
201
202		if (page_to_pfn(page) <= queue_bounce_pfn(q))
203			continue;
204
205		to->bv_page = mempool_alloc(pool, q->bounce_gfp);
206		inc_zone_page_state(to->bv_page, NR_BOUNCE);
207
208		if (rw == WRITE) {
209			char *vto, *vfrom;
210
211			flush_dcache_page(page);
212
213			vto = page_address(to->bv_page) + to->bv_offset;
214			vfrom = kmap_atomic(page) + to->bv_offset;
215			memcpy(vto, vfrom, to->bv_len);
216			kunmap_atomic(vfrom);
217		}
218	}
219
220	trace_block_bio_bounce(q, *bio_orig);
221
222	bio->bi_flags |= (1 << BIO_BOUNCED);
223
224	if (pool == page_pool) {
225		bio->bi_end_io = bounce_end_io_write;
226		if (rw == READ)
227			bio->bi_end_io = bounce_end_io_read;
228	} else {
229		bio->bi_end_io = bounce_end_io_write_isa;
230		if (rw == READ)
231			bio->bi_end_io = bounce_end_io_read_isa;
232	}
233
234	bio->bi_private = *bio_orig;
235	*bio_orig = bio;
236}
237
238void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
239{
240	mempool_t *pool;
241
242	/*
243	 * Data-less bio, nothing to bounce
244	 */
245	if (!bio_has_data(*bio_orig))
246		return;
247
248	/*
249	 * for non-isa bounce case, just check if the bounce pfn is equal
250	 * to or bigger than the highest pfn in the system -- in that case,
251	 * don't waste time iterating over bio segments
252	 */
253	if (!(q->bounce_gfp & GFP_DMA)) {
254		if (queue_bounce_pfn(q) >= blk_max_pfn)
255			return;
256		pool = page_pool;
257	} else {
258		BUG_ON(!isa_page_pool);
259		pool = isa_page_pool;
260	}
261
262	/*
263	 * slow path
264	 */
265	__blk_queue_bounce(q, bio_orig, pool);
266}
267
268EXPORT_SYMBOL(blk_queue_bounce);