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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 | |
25 | static mempool_t *page_pool, *isa_page_pool; |
26 | |
27 | #ifdef CONFIG_HIGHMEM |
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 | */ |
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 | */ |
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 | */ |
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 | */ |
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 | |
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 | |
148 | static void bounce_end_io_write(struct bio *bio, int err) |
149 | { |
150 | bounce_end_io(bio, page_pool, err); |
151 | } |
152 | |
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 | |
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 | |
169 | static void bounce_end_io_read(struct bio *bio, int err) |
170 | { |
171 | __bounce_end_io_read(bio, page_pool, err); |
172 | } |
173 | |
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 | |
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 | |
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 |
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