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/bio.h>
10 #include <linux/pagemap.h>
11 #include <linux/mempool.h>
12 #include <linux/blkdev.h>
13 #include <linux/init.h>
14 #include <linux/hash.h>
15 #include <linux/highmem.h>
16 #include <linux/blktrace_api.h>
17 #include <trace/block.h>
18 #include <asm/tlbflush.h>
19
20 #define POOL_SIZE 64
21 #define ISA_POOL_SIZE 16
22
23 static mempool_t *page_pool, *isa_page_pool;
24
25 DEFINE_TRACE(block_bio_bounce);
26
27 #ifdef CONFIG_HIGHMEM
init_emergency_pool(void)28 static __init int init_emergency_pool(void)
29 {
30 struct sysinfo i;
31 si_meminfo(&i);
32 si_swapinfo(&i);
33
34 if (!i.totalhigh)
35 return 0;
36
37 page_pool = mempool_create_page_pool(POOL_SIZE, 0);
38 BUG_ON(!page_pool);
39 printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
40
41 return 0;
42 }
43
44 __initcall(init_emergency_pool);
45
46 /*
47 * highmem version, map in to vec
48 */
bounce_copy_vec(struct bio_vec * to,unsigned char * vfrom)49 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
50 {
51 unsigned long flags;
52 unsigned char *vto;
53
54 local_irq_save(flags);
55 vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ);
56 memcpy(vto + to->bv_offset, vfrom, to->bv_len);
57 kunmap_atomic(vto, KM_BOUNCE_READ);
58 local_irq_restore(flags);
59 }
60
61 #else /* CONFIG_HIGHMEM */
62
63 #define bounce_copy_vec(to, vfrom) \
64 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
65
66 #endif /* CONFIG_HIGHMEM */
67
68 /*
69 * allocate pages in the DMA region for the ISA pool
70 */
mempool_alloc_pages_isa(gfp_t gfp_mask,void * data)71 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
72 {
73 return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
74 }
75
76 /*
77 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
78 * as the max address, so check if the pool has already been created.
79 */
init_emergency_isa_pool(void)80 int init_emergency_isa_pool(void)
81 {
82 if (isa_page_pool)
83 return 0;
84
85 isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
86 mempool_free_pages, (void *) 0);
87 BUG_ON(!isa_page_pool);
88
89 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
90 return 0;
91 }
92
93 /*
94 * Simple bounce buffer support for highmem pages. Depending on the
95 * queue gfp mask set, *to may or may not be a highmem page. kmap it
96 * always, it will do the Right Thing
97 */
copy_to_high_bio_irq(struct bio * to,struct bio * from)98 static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
99 {
100 unsigned char *vfrom;
101 struct bio_vec *tovec, *fromvec;
102 int i;
103
104 __bio_for_each_segment(tovec, to, i, 0) {
105 fromvec = from->bi_io_vec + i;
106
107 /*
108 * not bounced
109 */
110 if (tovec->bv_page == fromvec->bv_page)
111 continue;
112
113 /*
114 * fromvec->bv_offset and fromvec->bv_len might have been
115 * modified by the block layer, so use the original copy,
116 * bounce_copy_vec already uses tovec->bv_len
117 */
118 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
119
120 flush_dcache_page(tovec->bv_page);
121 bounce_copy_vec(tovec, vfrom);
122 }
123 }
124
bounce_end_io(struct bio * bio,mempool_t * pool,int err)125 static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
126 {
127 struct bio *bio_orig = bio->bi_private;
128 struct bio_vec *bvec, *org_vec;
129 int i;
130
131 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
132 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
133
134 /*
135 * free up bounce indirect pages used
136 */
137 __bio_for_each_segment(bvec, bio, i, 0) {
138 org_vec = bio_orig->bi_io_vec + i;
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_endio(bio_orig, err);
147 bio_put(bio);
148 }
149
bounce_end_io_write(struct bio * bio,int err)150 static void bounce_end_io_write(struct bio *bio, int err)
151 {
152 bounce_end_io(bio, page_pool, err);
153 }
154
bounce_end_io_write_isa(struct bio * bio,int err)155 static void bounce_end_io_write_isa(struct bio *bio, int err)
156 {
157
158 bounce_end_io(bio, isa_page_pool, err);
159 }
160
__bounce_end_io_read(struct bio * bio,mempool_t * pool,int err)161 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
162 {
163 struct bio *bio_orig = bio->bi_private;
164
165 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
166 copy_to_high_bio_irq(bio_orig, bio);
167
168 bounce_end_io(bio, pool, err);
169 }
170
bounce_end_io_read(struct bio * bio,int err)171 static void bounce_end_io_read(struct bio *bio, int err)
172 {
173 __bounce_end_io_read(bio, page_pool, err);
174 }
175
bounce_end_io_read_isa(struct bio * bio,int err)176 static void bounce_end_io_read_isa(struct bio *bio, int err)
177 {
178 __bounce_end_io_read(bio, isa_page_pool, err);
179 }
180
__blk_queue_bounce(struct request_queue * q,struct bio ** bio_orig,mempool_t * pool)181 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
182 mempool_t *pool)
183 {
184 struct page *page;
185 struct bio *bio = NULL;
186 int i, rw = bio_data_dir(*bio_orig);
187 struct bio_vec *to, *from;
188
189 bio_for_each_segment(from, *bio_orig, i) {
190 page = from->bv_page;
191
192 /*
193 * is destination page below bounce pfn?
194 */
195 if (page_to_pfn(page) <= q->bounce_pfn)
196 continue;
197
198 /*
199 * irk, bounce it
200 */
201 if (!bio) {
202 unsigned int cnt = (*bio_orig)->bi_vcnt;
203
204 bio = bio_alloc(GFP_NOIO, cnt);
205 memset(bio->bi_io_vec, 0, cnt * sizeof(struct bio_vec));
206 }
207
208
209 to = bio->bi_io_vec + i;
210
211 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
212 to->bv_len = from->bv_len;
213 to->bv_offset = from->bv_offset;
214 inc_zone_page_state(to->bv_page, NR_BOUNCE);
215
216 if (rw == WRITE) {
217 char *vto, *vfrom;
218
219 flush_dcache_page(from->bv_page);
220 vto = page_address(to->bv_page) + to->bv_offset;
221 vfrom = kmap(from->bv_page) + from->bv_offset;
222 memcpy(vto, vfrom, to->bv_len);
223 kunmap(from->bv_page);
224 }
225 }
226
227 /*
228 * no pages bounced
229 */
230 if (!bio)
231 return;
232
233 trace_block_bio_bounce(q, *bio_orig);
234
235 /*
236 * at least one page was bounced, fill in possible non-highmem
237 * pages
238 */
239 __bio_for_each_segment(from, *bio_orig, i, 0) {
240 to = bio_iovec_idx(bio, i);
241 if (!to->bv_page) {
242 to->bv_page = from->bv_page;
243 to->bv_len = from->bv_len;
244 to->bv_offset = from->bv_offset;
245 }
246 }
247
248 bio->bi_bdev = (*bio_orig)->bi_bdev;
249 bio->bi_flags |= (1 << BIO_BOUNCED);
250 bio->bi_sector = (*bio_orig)->bi_sector;
251 bio->bi_rw = (*bio_orig)->bi_rw;
252
253 bio->bi_vcnt = (*bio_orig)->bi_vcnt;
254 bio->bi_idx = (*bio_orig)->bi_idx;
255 bio->bi_size = (*bio_orig)->bi_size;
256
257 if (pool == page_pool) {
258 bio->bi_end_io = bounce_end_io_write;
259 if (rw == READ)
260 bio->bi_end_io = bounce_end_io_read;
261 } else {
262 bio->bi_end_io = bounce_end_io_write_isa;
263 if (rw == READ)
264 bio->bi_end_io = bounce_end_io_read_isa;
265 }
266
267 bio->bi_private = *bio_orig;
268 *bio_orig = bio;
269 }
270
blk_queue_bounce(struct request_queue * q,struct bio ** bio_orig)271 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
272 {
273 mempool_t *pool;
274
275 /*
276 * Data-less bio, nothing to bounce
277 */
278 if (!bio_has_data(*bio_orig))
279 return;
280
281 /*
282 * for non-isa bounce case, just check if the bounce pfn is equal
283 * to or bigger than the highest pfn in the system -- in that case,
284 * don't waste time iterating over bio segments
285 */
286 if (!(q->bounce_gfp & GFP_DMA)) {
287 if (q->bounce_pfn >= blk_max_pfn)
288 return;
289 pool = page_pool;
290 } else {
291 BUG_ON(!isa_page_pool);
292 pool = isa_page_pool;
293 }
294
295 /*
296 * slow path
297 */
298 __blk_queue_bounce(q, bio_orig, pool);
299 }
300
301 EXPORT_SYMBOL(blk_queue_bounce);
302