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
25 static mempool_t *page_pool, *isa_page_pool;
26
27 #ifdef CONFIG_HIGHMEM
init_emergency_pool(void)28 static __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 */
bounce_copy_vec(struct bio_vec * to,unsigned char * vfrom)47 static 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, KM_BOUNCE_READ);
54 memcpy(vto + to->bv_offset, vfrom, to->bv_len);
55 kunmap_atomic(vto, KM_BOUNCE_READ);
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 */
mempool_alloc_pages_isa(gfp_t gfp_mask,void * data)69 static 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 */
init_emergency_isa_pool(void)78 int 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 */
copy_to_high_bio_irq(struct bio * to,struct bio * from)96 static 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
bounce_end_io(struct bio * bio,mempool_t * pool,int err)123 static 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
bounce_end_io_write(struct bio * bio,int err)148 static void bounce_end_io_write(struct bio *bio, int err)
149 {
150 bounce_end_io(bio, page_pool, err);
151 }
152
bounce_end_io_write_isa(struct bio * bio,int err)153 static void bounce_end_io_write_isa(struct bio *bio, int err)
154 {
155
156 bounce_end_io(bio, isa_page_pool, err);
157 }
158
__bounce_end_io_read(struct bio * bio,mempool_t * pool,int err)159 static 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
bounce_end_io_read(struct bio * bio,int err)169 static void bounce_end_io_read(struct bio *bio, int err)
170 {
171 __bounce_end_io_read(bio, page_pool, err);
172 }
173
bounce_end_io_read_isa(struct bio * bio,int err)174 static void bounce_end_io_read_isa(struct bio *bio, int err)
175 {
176 __bounce_end_io_read(bio, isa_page_pool, err);
177 }
178
__blk_queue_bounce(struct request_queue * q,struct bio ** bio_orig,mempool_t * pool)179 static 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
blk_queue_bounce(struct request_queue * q,struct bio ** bio_orig)269 void 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
299 EXPORT_SYMBOL(blk_queue_bounce);
300