1 /* bounce buffer handling for block devices
2 *
3 * - Split from highmem.c
4 */
5
6 #include <linux/mm.h>
7 #include <linux/module.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 <asm/tlbflush.h>
18
19 #include <trace/events/block.h>
20
21 #define POOL_SIZE 64
22 #define ISA_POOL_SIZE 16
23
24 static mempool_t *page_pool, *isa_page_pool;
25
26 #ifdef CONFIG_HIGHMEM
init_emergency_pool(void)27 static __init int init_emergency_pool(void)
28 {
29 struct sysinfo i;
30 si_meminfo(&i);
31 si_swapinfo(&i);
32
33 if (!i.totalhigh)
34 return 0;
35
36 page_pool = mempool_create_page_pool(POOL_SIZE, 0);
37 BUG_ON(!page_pool);
38 printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
39
40 return 0;
41 }
42
43 __initcall(init_emergency_pool);
44
45 /*
46 * highmem version, map in to vec
47 */
bounce_copy_vec(struct bio_vec * to,unsigned char * vfrom)48 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
49 {
50 unsigned long flags;
51 unsigned char *vto;
52
53 local_irq_save(flags);
54 vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ);
55 memcpy(vto + to->bv_offset, vfrom, to->bv_len);
56 kunmap_atomic(vto, KM_BOUNCE_READ);
57 local_irq_restore(flags);
58 }
59
60 #else /* CONFIG_HIGHMEM */
61
62 #define bounce_copy_vec(to, vfrom) \
63 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
64
65 #endif /* CONFIG_HIGHMEM */
66
67 /*
68 * allocate pages in the DMA region for the ISA pool
69 */
mempool_alloc_pages_isa(gfp_t gfp_mask,void * data)70 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
71 {
72 return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
73 }
74
75 /*
76 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
77 * as the max address, so check if the pool has already been created.
78 */
init_emergency_isa_pool(void)79 int init_emergency_isa_pool(void)
80 {
81 if (isa_page_pool)
82 return 0;
83
84 isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
85 mempool_free_pages, (void *) 0);
86 BUG_ON(!isa_page_pool);
87
88 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
89 return 0;
90 }
91
92 /*
93 * Simple bounce buffer support for highmem pages. Depending on the
94 * queue gfp mask set, *to may or may not be a highmem page. kmap it
95 * always, it will do the Right Thing
96 */
copy_to_high_bio_irq(struct bio * to,struct bio * from)97 static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
98 {
99 unsigned char *vfrom;
100 struct bio_vec *tovec, *fromvec;
101 int i;
102
103 __bio_for_each_segment(tovec, to, i, 0) {
104 fromvec = from->bi_io_vec + i;
105
106 /*
107 * not bounced
108 */
109 if (tovec->bv_page == fromvec->bv_page)
110 continue;
111
112 /*
113 * fromvec->bv_offset and fromvec->bv_len might have been
114 * modified by the block layer, so use the original copy,
115 * bounce_copy_vec already uses tovec->bv_len
116 */
117 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
118
119 bounce_copy_vec(tovec, vfrom);
120 flush_dcache_page(tovec->bv_page);
121 }
122 }
123
bounce_end_io(struct bio * bio,mempool_t * pool,int err)124 static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
125 {
126 struct bio *bio_orig = bio->bi_private;
127 struct bio_vec *bvec, *org_vec;
128 int i;
129
130 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
131 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
132
133 /*
134 * free up bounce indirect pages used
135 */
136 __bio_for_each_segment(bvec, bio, i, 0) {
137 org_vec = bio_orig->bi_io_vec + i;
138 if (bvec->bv_page == org_vec->bv_page)
139 continue;
140
141 dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
142 mempool_free(bvec->bv_page, pool);
143 }
144
145 bio_endio(bio_orig, err);
146 bio_put(bio);
147 }
148
bounce_end_io_write(struct bio * bio,int err)149 static void bounce_end_io_write(struct bio *bio, int err)
150 {
151 bounce_end_io(bio, page_pool, err);
152 }
153
bounce_end_io_write_isa(struct bio * bio,int err)154 static void bounce_end_io_write_isa(struct bio *bio, int err)
155 {
156
157 bounce_end_io(bio, isa_page_pool, err);
158 }
159
__bounce_end_io_read(struct bio * bio,mempool_t * pool,int err)160 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
161 {
162 struct bio *bio_orig = bio->bi_private;
163
164 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
165 copy_to_high_bio_irq(bio_orig, bio);
166
167 bounce_end_io(bio, pool, err);
168 }
169
bounce_end_io_read(struct bio * bio,int err)170 static void bounce_end_io_read(struct bio *bio, int err)
171 {
172 __bounce_end_io_read(bio, page_pool, err);
173 }
174
bounce_end_io_read_isa(struct bio * bio,int err)175 static void bounce_end_io_read_isa(struct bio *bio, int err)
176 {
177 __bounce_end_io_read(bio, isa_page_pool, err);
178 }
179
__blk_queue_bounce(struct request_queue * q,struct bio ** bio_orig,mempool_t * pool)180 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
181 mempool_t *pool)
182 {
183 struct page *page;
184 struct bio *bio = NULL;
185 int i, rw = bio_data_dir(*bio_orig);
186 struct bio_vec *to, *from;
187
188 bio_for_each_segment(from, *bio_orig, i) {
189 page = from->bv_page;
190
191 /*
192 * is destination page below bounce pfn?
193 */
194 if (page_to_pfn(page) <= queue_bounce_pfn(q))
195 continue;
196
197 /*
198 * irk, bounce it
199 */
200 if (!bio) {
201 unsigned int cnt = (*bio_orig)->bi_vcnt;
202
203 bio = bio_alloc(GFP_NOIO, cnt);
204 memset(bio->bi_io_vec, 0, cnt * sizeof(struct bio_vec));
205 }
206
207
208 to = bio->bi_io_vec + i;
209
210 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
211 to->bv_len = from->bv_len;
212 to->bv_offset = from->bv_offset;
213 inc_zone_page_state(to->bv_page, NR_BOUNCE);
214
215 if (rw == WRITE) {
216 char *vto, *vfrom;
217
218 flush_dcache_page(from->bv_page);
219 vto = page_address(to->bv_page) + to->bv_offset;
220 vfrom = kmap(from->bv_page) + from->bv_offset;
221 memcpy(vto, vfrom, to->bv_len);
222 kunmap(from->bv_page);
223 }
224 }
225
226 /*
227 * no pages bounced
228 */
229 if (!bio)
230 return;
231
232 trace_block_bio_bounce(q, *bio_orig);
233
234 /*
235 * at least one page was bounced, fill in possible non-highmem
236 * pages
237 */
238 __bio_for_each_segment(from, *bio_orig, i, 0) {
239 to = bio_iovec_idx(bio, i);
240 if (!to->bv_page) {
241 to->bv_page = from->bv_page;
242 to->bv_len = from->bv_len;
243 to->bv_offset = from->bv_offset;
244 }
245 }
246
247 bio->bi_bdev = (*bio_orig)->bi_bdev;
248 bio->bi_flags |= (1 << BIO_BOUNCED);
249 bio->bi_sector = (*bio_orig)->bi_sector;
250 bio->bi_rw = (*bio_orig)->bi_rw;
251
252 bio->bi_vcnt = (*bio_orig)->bi_vcnt;
253 bio->bi_idx = (*bio_orig)->bi_idx;
254 bio->bi_size = (*bio_orig)->bi_size;
255
256 if (pool == page_pool) {
257 bio->bi_end_io = bounce_end_io_write;
258 if (rw == READ)
259 bio->bi_end_io = bounce_end_io_read;
260 } else {
261 bio->bi_end_io = bounce_end_io_write_isa;
262 if (rw == READ)
263 bio->bi_end_io = bounce_end_io_read_isa;
264 }
265
266 bio->bi_private = *bio_orig;
267 *bio_orig = bio;
268 }
269
blk_queue_bounce(struct request_queue * q,struct bio ** bio_orig)270 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
271 {
272 mempool_t *pool;
273
274 /*
275 * Data-less bio, nothing to bounce
276 */
277 if (!bio_has_data(*bio_orig))
278 return;
279
280 /*
281 * for non-isa bounce case, just check if the bounce pfn is equal
282 * to or bigger than the highest pfn in the system -- in that case,
283 * don't waste time iterating over bio segments
284 */
285 if (!(q->bounce_gfp & GFP_DMA)) {
286 if (queue_bounce_pfn(q) >= blk_max_pfn)
287 return;
288 pool = page_pool;
289 } else {
290 BUG_ON(!isa_page_pool);
291 pool = isa_page_pool;
292 }
293
294 /*
295 * slow path
296 */
297 __blk_queue_bounce(q, bio_orig, pool);
298 }
299
300 EXPORT_SYMBOL(blk_queue_bounce);
301