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1/* bounce buffer handling for block devices
2 *
3 * - Split from highmem.c
4 */
5
6#include <linux/mm.h>
7#include <linux/export.h>
8#include <linux/swap.h>
9#include <linux/gfp.h>
10#include <linux/bio.h>
11#include <linux/pagemap.h>
12#include <linux/mempool.h>
13#include <linux/blkdev.h>
14#include <linux/init.h>
15#include <linux/hash.h>
16#include <linux/highmem.h>
17#include <linux/bootmem.h>
18#include <asm/tlbflush.h>
19
20#include <trace/events/block.h>
21
22#define POOL_SIZE 64
23#define ISA_POOL_SIZE 16
24
25static mempool_t *page_pool, *isa_page_pool;
26
27#ifdef CONFIG_HIGHMEM
28static __init int init_emergency_pool(void)
29{
30#ifndef CONFIG_MEMORY_HOTPLUG
31 if (max_pfn <= max_low_pfn)
32 return 0;
33#endif
34
35 page_pool = mempool_create_page_pool(POOL_SIZE, 0);
36 BUG_ON(!page_pool);
37 printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
38
39 return 0;
40}
41
42__initcall(init_emergency_pool);
43
44/*
45 * highmem version, map in to vec
46 */
47static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
48{
49 unsigned long flags;
50 unsigned char *vto;
51
52 local_irq_save(flags);
53 vto = kmap_atomic(to->bv_page);
54 memcpy(vto + to->bv_offset, vfrom, to->bv_len);
55 kunmap_atomic(vto);
56 local_irq_restore(flags);
57}
58
59#else /* CONFIG_HIGHMEM */
60
61#define bounce_copy_vec(to, vfrom) \
62 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
63
64#endif /* CONFIG_HIGHMEM */
65
66/*
67 * allocate pages in the DMA region for the ISA pool
68 */
69static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
70{
71 return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
72}
73
74/*
75 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
76 * as the max address, so check if the pool has already been created.
77 */
78int init_emergency_isa_pool(void)
79{
80 if (isa_page_pool)
81 return 0;
82
83 isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
84 mempool_free_pages, (void *) 0);
85 BUG_ON(!isa_page_pool);
86
87 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
88 return 0;
89}
90
91/*
92 * Simple bounce buffer support for highmem pages. Depending on the
93 * queue gfp mask set, *to may or may not be a highmem page. kmap it
94 * always, it will do the Right Thing
95 */
96static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
97{
98 unsigned char *vfrom;
99 struct bio_vec *tovec, *fromvec;
100 int i;
101
102 __bio_for_each_segment(tovec, to, i, 0) {
103 fromvec = from->bi_io_vec + i;
104
105 /*
106 * not bounced
107 */
108 if (tovec->bv_page == fromvec->bv_page)
109 continue;
110
111 /*
112 * fromvec->bv_offset and fromvec->bv_len might have been
113 * modified by the block layer, so use the original copy,
114 * bounce_copy_vec already uses tovec->bv_len
115 */
116 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
117
118 bounce_copy_vec(tovec, vfrom);
119 flush_dcache_page(tovec->bv_page);
120 }
121}
122
123static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
124{
125 struct bio *bio_orig = bio->bi_private;
126 struct bio_vec *bvec, *org_vec;
127 int i;
128
129 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
130 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
131
132 /*
133 * free up bounce indirect pages used
134 */
135 __bio_for_each_segment(bvec, bio, i, 0) {
136 org_vec = bio_orig->bi_io_vec + i;
137 if (bvec->bv_page == org_vec->bv_page)
138 continue;
139
140 dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
141 mempool_free(bvec->bv_page, pool);
142 }
143
144 bio_endio(bio_orig, err);
145 bio_put(bio);
146}
147
148static void bounce_end_io_write(struct bio *bio, int err)
149{
150 bounce_end_io(bio, page_pool, err);
151}
152
153static void bounce_end_io_write_isa(struct bio *bio, int err)
154{
155
156 bounce_end_io(bio, isa_page_pool, err);
157}
158
159static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
160{
161 struct bio *bio_orig = bio->bi_private;
162
163 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
164 copy_to_high_bio_irq(bio_orig, bio);
165
166 bounce_end_io(bio, pool, err);
167}
168
169static void bounce_end_io_read(struct bio *bio, int err)
170{
171 __bounce_end_io_read(bio, page_pool, err);
172}
173
174static void bounce_end_io_read_isa(struct bio *bio, int err)
175{
176 __bounce_end_io_read(bio, isa_page_pool, err);
177}
178
179static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
180 mempool_t *pool)
181{
182 struct page *page;
183 struct bio *bio = NULL;
184 int i, rw = bio_data_dir(*bio_orig);
185 struct bio_vec *to, *from;
186
187 bio_for_each_segment(from, *bio_orig, i) {
188 page = from->bv_page;
189
190 /*
191 * is destination page below bounce pfn?
192 */
193 if (page_to_pfn(page) <= queue_bounce_pfn(q))
194 continue;
195
196 /*
197 * irk, bounce it
198 */
199 if (!bio) {
200 unsigned int cnt = (*bio_orig)->bi_vcnt;
201
202 bio = bio_alloc(GFP_NOIO, cnt);
203 memset(bio->bi_io_vec, 0, cnt * sizeof(struct bio_vec));
204 }
205
206
207 to = bio->bi_io_vec + i;
208
209 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
210 to->bv_len = from->bv_len;
211 to->bv_offset = from->bv_offset;
212 inc_zone_page_state(to->bv_page, NR_BOUNCE);
213
214 if (rw == WRITE) {
215 char *vto, *vfrom;
216
217 flush_dcache_page(from->bv_page);
218 vto = page_address(to->bv_page) + to->bv_offset;
219 vfrom = kmap(from->bv_page) + from->bv_offset;
220 memcpy(vto, vfrom, to->bv_len);
221 kunmap(from->bv_page);
222 }
223 }
224
225 /*
226 * no pages bounced
227 */
228 if (!bio)
229 return;
230
231 trace_block_bio_bounce(q, *bio_orig);
232
233 /*
234 * at least one page was bounced, fill in possible non-highmem
235 * pages
236 */
237 __bio_for_each_segment(from, *bio_orig, i, 0) {
238 to = bio_iovec_idx(bio, i);
239 if (!to->bv_page) {
240 to->bv_page = from->bv_page;
241 to->bv_len = from->bv_len;
242 to->bv_offset = from->bv_offset;
243 }
244 }
245
246 bio->bi_bdev = (*bio_orig)->bi_bdev;
247 bio->bi_flags |= (1 << BIO_BOUNCED);
248 bio->bi_sector = (*bio_orig)->bi_sector;
249 bio->bi_rw = (*bio_orig)->bi_rw;
250
251 bio->bi_vcnt = (*bio_orig)->bi_vcnt;
252 bio->bi_idx = (*bio_orig)->bi_idx;
253 bio->bi_size = (*bio_orig)->bi_size;
254
255 if (pool == page_pool) {
256 bio->bi_end_io = bounce_end_io_write;
257 if (rw == READ)
258 bio->bi_end_io = bounce_end_io_read;
259 } else {
260 bio->bi_end_io = bounce_end_io_write_isa;
261 if (rw == READ)
262 bio->bi_end_io = bounce_end_io_read_isa;
263 }
264
265 bio->bi_private = *bio_orig;
266 *bio_orig = bio;
267}
268
269void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
270{
271 mempool_t *pool;
272
273 /*
274 * Data-less bio, nothing to bounce
275 */
276 if (!bio_has_data(*bio_orig))
277 return;
278
279 /*
280 * for non-isa bounce case, just check if the bounce pfn is equal
281 * to or bigger than the highest pfn in the system -- in that case,
282 * don't waste time iterating over bio segments
283 */
284 if (!(q->bounce_gfp & GFP_DMA)) {
285 if (queue_bounce_pfn(q) >= blk_max_pfn)
286 return;
287 pool = page_pool;
288 } else {
289 BUG_ON(!isa_page_pool);
290 pool = isa_page_pool;
291 }
292
293 /*
294 * slow path
295 */
296 __blk_queue_bounce(q, bio_orig, pool);
297}
298
299EXPORT_SYMBOL(blk_queue_bounce);