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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 | #if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL) |
28 | static __init int init_emergency_pool(void) |
29 | { |
30 | #if defined(CONFIG_HIGHMEM) && !defined(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("bounce pool size: %d pages\n", POOL_SIZE); |
38 | |
39 | return 0; |
40 | } |
41 | |
42 | __initcall(init_emergency_pool); |
43 | #endif |
44 | |
45 | #ifdef CONFIG_HIGHMEM |
46 | /* |
47 | * highmem version, map in to vec |
48 | */ |
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); |
56 | memcpy(vto + to->bv_offset, vfrom, to->bv_len); |
57 | kunmap_atomic(vto); |
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 | */ |
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 | */ |
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 | */ |
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 | bounce_copy_vec(tovec, vfrom); |
121 | flush_dcache_page(tovec->bv_page); |
122 | } |
123 | } |
124 | |
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 | |
150 | static void bounce_end_io_write(struct bio *bio, int err) |
151 | { |
152 | bounce_end_io(bio, page_pool, err); |
153 | } |
154 | |
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 | |
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 | |
171 | static void bounce_end_io_read(struct bio *bio, int err) |
172 | { |
173 | __bounce_end_io_read(bio, page_pool, err); |
174 | } |
175 | |
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 | |
181 | #ifdef CONFIG_NEED_BOUNCE_POOL |
182 | static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) |
183 | { |
184 | struct page *page; |
185 | struct backing_dev_info *bdi; |
186 | struct address_space *mapping; |
187 | struct bio_vec *from; |
188 | int i; |
189 | |
190 | if (bio_data_dir(bio) != WRITE) |
191 | return 0; |
192 | |
193 | if (!bdi_cap_stable_pages_required(&q->backing_dev_info)) |
194 | return 0; |
195 | |
196 | /* |
197 | * Based on the first page that has a valid mapping, decide whether or |
198 | * not we have to employ bounce buffering to guarantee stable pages. |
199 | */ |
200 | bio_for_each_segment(from, bio, i) { |
201 | page = from->bv_page; |
202 | mapping = page_mapping(page); |
203 | if (!mapping) |
204 | continue; |
205 | bdi = mapping->backing_dev_info; |
206 | return mapping->host->i_sb->s_flags & MS_SNAP_STABLE; |
207 | } |
208 | |
209 | return 0; |
210 | } |
211 | #else |
212 | static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) |
213 | { |
214 | return 0; |
215 | } |
216 | #endif /* CONFIG_NEED_BOUNCE_POOL */ |
217 | |
218 | static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, |
219 | mempool_t *pool, int force) |
220 | { |
221 | struct page *page; |
222 | struct bio *bio = NULL; |
223 | int i, rw = bio_data_dir(*bio_orig); |
224 | struct bio_vec *to, *from; |
225 | |
226 | bio_for_each_segment(from, *bio_orig, i) { |
227 | page = from->bv_page; |
228 | |
229 | /* |
230 | * is destination page below bounce pfn? |
231 | */ |
232 | if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force) |
233 | continue; |
234 | |
235 | /* |
236 | * irk, bounce it |
237 | */ |
238 | if (!bio) { |
239 | unsigned int cnt = (*bio_orig)->bi_vcnt; |
240 | |
241 | bio = bio_alloc(GFP_NOIO, cnt); |
242 | memset(bio->bi_io_vec, 0, cnt * sizeof(struct bio_vec)); |
243 | } |
244 | |
245 | |
246 | to = bio->bi_io_vec + i; |
247 | |
248 | to->bv_page = mempool_alloc(pool, q->bounce_gfp); |
249 | to->bv_len = from->bv_len; |
250 | to->bv_offset = from->bv_offset; |
251 | inc_zone_page_state(to->bv_page, NR_BOUNCE); |
252 | |
253 | if (rw == WRITE) { |
254 | char *vto, *vfrom; |
255 | |
256 | flush_dcache_page(from->bv_page); |
257 | vto = page_address(to->bv_page) + to->bv_offset; |
258 | vfrom = kmap(from->bv_page) + from->bv_offset; |
259 | memcpy(vto, vfrom, to->bv_len); |
260 | kunmap(from->bv_page); |
261 | } |
262 | } |
263 | |
264 | /* |
265 | * no pages bounced |
266 | */ |
267 | if (!bio) |
268 | return; |
269 | |
270 | trace_block_bio_bounce(q, *bio_orig); |
271 | |
272 | /* |
273 | * at least one page was bounced, fill in possible non-highmem |
274 | * pages |
275 | */ |
276 | __bio_for_each_segment(from, *bio_orig, i, 0) { |
277 | to = bio_iovec_idx(bio, i); |
278 | if (!to->bv_page) { |
279 | to->bv_page = from->bv_page; |
280 | to->bv_len = from->bv_len; |
281 | to->bv_offset = from->bv_offset; |
282 | } |
283 | } |
284 | |
285 | bio->bi_bdev = (*bio_orig)->bi_bdev; |
286 | bio->bi_flags |= (1 << BIO_BOUNCED); |
287 | bio->bi_sector = (*bio_orig)->bi_sector; |
288 | bio->bi_rw = (*bio_orig)->bi_rw; |
289 | |
290 | bio->bi_vcnt = (*bio_orig)->bi_vcnt; |
291 | bio->bi_idx = (*bio_orig)->bi_idx; |
292 | bio->bi_size = (*bio_orig)->bi_size; |
293 | |
294 | if (pool == page_pool) { |
295 | bio->bi_end_io = bounce_end_io_write; |
296 | if (rw == READ) |
297 | bio->bi_end_io = bounce_end_io_read; |
298 | } else { |
299 | bio->bi_end_io = bounce_end_io_write_isa; |
300 | if (rw == READ) |
301 | bio->bi_end_io = bounce_end_io_read_isa; |
302 | } |
303 | |
304 | bio->bi_private = *bio_orig; |
305 | *bio_orig = bio; |
306 | } |
307 | |
308 | void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) |
309 | { |
310 | int must_bounce; |
311 | mempool_t *pool; |
312 | |
313 | /* |
314 | * Data-less bio, nothing to bounce |
315 | */ |
316 | if (!bio_has_data(*bio_orig)) |
317 | return; |
318 | |
319 | must_bounce = must_snapshot_stable_pages(q, *bio_orig); |
320 | |
321 | /* |
322 | * for non-isa bounce case, just check if the bounce pfn is equal |
323 | * to or bigger than the highest pfn in the system -- in that case, |
324 | * don't waste time iterating over bio segments |
325 | */ |
326 | if (!(q->bounce_gfp & GFP_DMA)) { |
327 | if (queue_bounce_pfn(q) >= blk_max_pfn && !must_bounce) |
328 | return; |
329 | pool = page_pool; |
330 | } else { |
331 | BUG_ON(!isa_page_pool); |
332 | pool = isa_page_pool; |
333 | } |
334 | |
335 | /* |
336 | * slow path |
337 | */ |
338 | __blk_queue_bounce(q, bio_orig, pool, must_bounce); |
339 | } |
340 | |
341 | EXPORT_SYMBOL(blk_queue_bounce); |
342 |
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