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1 | /* bounce buffer handling for block devices | |
2 | * | |
3 | * - Split from highmem.c | |
4 | */ | |
5 | ||
6 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
7 | ||
8 | #include <linux/mm.h> | |
9 | #include <linux/export.h> | |
10 | #include <linux/swap.h> | |
11 | #include <linux/gfp.h> | |
12 | #include <linux/bio.h> | |
13 | #include <linux/pagemap.h> | |
14 | #include <linux/mempool.h> | |
15 | #include <linux/blkdev.h> | |
16 | #include <linux/backing-dev.h> | |
17 | #include <linux/init.h> | |
18 | #include <linux/hash.h> | |
19 | #include <linux/highmem.h> | |
20 | #include <linux/bootmem.h> | |
21 | #include <linux/printk.h> | |
22 | #include <asm/tlbflush.h> | |
23 | ||
24 | #include <trace/events/block.h> | |
25 | ||
26 | #define POOL_SIZE 64 | |
27 | #define ISA_POOL_SIZE 16 | |
28 | ||
29 | static mempool_t *page_pool, *isa_page_pool; | |
30 | ||
31 | #if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL) | |
32 | static __init int init_emergency_pool(void) | |
33 | { | |
34 | #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG) | |
35 | if (max_pfn <= max_low_pfn) | |
36 | return 0; | |
37 | #endif | |
38 | ||
39 | page_pool = mempool_create_page_pool(POOL_SIZE, 0); | |
40 | BUG_ON(!page_pool); | |
41 | pr_info("pool size: %d pages\n", POOL_SIZE); | |
42 | ||
43 | return 0; | |
44 | } | |
45 | ||
46 | __initcall(init_emergency_pool); | |
47 | #endif | |
48 | ||
49 | #ifdef CONFIG_HIGHMEM | |
50 | /* | |
51 | * highmem version, map in to vec | |
52 | */ | |
53 | static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) | |
54 | { | |
55 | unsigned long flags; | |
56 | unsigned char *vto; | |
57 | ||
58 | local_irq_save(flags); | |
59 | vto = kmap_atomic(to->bv_page); | |
60 | memcpy(vto + to->bv_offset, vfrom, to->bv_len); | |
61 | kunmap_atomic(vto); | |
62 | local_irq_restore(flags); | |
63 | } | |
64 | ||
65 | #else /* CONFIG_HIGHMEM */ | |
66 | ||
67 | #define bounce_copy_vec(to, vfrom) \ | |
68 | memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) | |
69 | ||
70 | #endif /* CONFIG_HIGHMEM */ | |
71 | ||
72 | /* | |
73 | * allocate pages in the DMA region for the ISA pool | |
74 | */ | |
75 | static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data) | |
76 | { | |
77 | return mempool_alloc_pages(gfp_mask | GFP_DMA, data); | |
78 | } | |
79 | ||
80 | /* | |
81 | * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA | |
82 | * as the max address, so check if the pool has already been created. | |
83 | */ | |
84 | int init_emergency_isa_pool(void) | |
85 | { | |
86 | if (isa_page_pool) | |
87 | return 0; | |
88 | ||
89 | isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa, | |
90 | mempool_free_pages, (void *) 0); | |
91 | BUG_ON(!isa_page_pool); | |
92 | ||
93 | pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE); | |
94 | return 0; | |
95 | } | |
96 | ||
97 | /* | |
98 | * Simple bounce buffer support for highmem pages. Depending on the | |
99 | * queue gfp mask set, *to may or may not be a highmem page. kmap it | |
100 | * always, it will do the Right Thing | |
101 | */ | |
102 | static void copy_to_high_bio_irq(struct bio *to, struct bio *from) | |
103 | { | |
104 | unsigned char *vfrom; | |
105 | struct bio_vec tovec, *fromvec = from->bi_io_vec; | |
106 | struct bvec_iter iter; | |
107 | ||
108 | bio_for_each_segment(tovec, to, iter) { | |
109 | if (tovec.bv_page != fromvec->bv_page) { | |
110 | /* | |
111 | * fromvec->bv_offset and fromvec->bv_len might have | |
112 | * been modified by the block layer, so use the original | |
113 | * copy, bounce_copy_vec already uses tovec->bv_len | |
114 | */ | |
115 | vfrom = page_address(fromvec->bv_page) + | |
116 | tovec.bv_offset; | |
117 | ||
118 | bounce_copy_vec(&tovec, vfrom); | |
119 | flush_dcache_page(tovec.bv_page); | |
120 | } | |
121 | ||
122 | fromvec++; | |
123 | } | |
124 | } | |
125 | ||
126 | static void bounce_end_io(struct bio *bio, mempool_t *pool) | |
127 | { | |
128 | struct bio *bio_orig = bio->bi_private; | |
129 | struct bio_vec *bvec, *org_vec; | |
130 | int i; | |
131 | ||
132 | /* | |
133 | * free up bounce indirect pages used | |
134 | */ | |
135 | bio_for_each_segment_all(bvec, bio, i) { | |
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_orig->bi_error = bio->bi_error; | |
145 | bio_endio(bio_orig); | |
146 | bio_put(bio); | |
147 | } | |
148 | ||
149 | static void bounce_end_io_write(struct bio *bio) | |
150 | { | |
151 | bounce_end_io(bio, page_pool); | |
152 | } | |
153 | ||
154 | static void bounce_end_io_write_isa(struct bio *bio) | |
155 | { | |
156 | ||
157 | bounce_end_io(bio, isa_page_pool); | |
158 | } | |
159 | ||
160 | static void __bounce_end_io_read(struct bio *bio, mempool_t *pool) | |
161 | { | |
162 | struct bio *bio_orig = bio->bi_private; | |
163 | ||
164 | if (!bio->bi_error) | |
165 | copy_to_high_bio_irq(bio_orig, bio); | |
166 | ||
167 | bounce_end_io(bio, pool); | |
168 | } | |
169 | ||
170 | static void bounce_end_io_read(struct bio *bio) | |
171 | { | |
172 | __bounce_end_io_read(bio, page_pool); | |
173 | } | |
174 | ||
175 | static void bounce_end_io_read_isa(struct bio *bio) | |
176 | { | |
177 | __bounce_end_io_read(bio, isa_page_pool); | |
178 | } | |
179 | ||
180 | #ifdef CONFIG_NEED_BOUNCE_POOL | |
181 | static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) | |
182 | { | |
183 | if (bio_data_dir(bio) != WRITE) | |
184 | return 0; | |
185 | ||
186 | if (!bdi_cap_stable_pages_required(&q->backing_dev_info)) | |
187 | return 0; | |
188 | ||
189 | return bio_flagged(bio, BIO_SNAP_STABLE); | |
190 | } | |
191 | #else | |
192 | static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) | |
193 | { | |
194 | return 0; | |
195 | } | |
196 | #endif /* CONFIG_NEED_BOUNCE_POOL */ | |
197 | ||
198 | static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, | |
199 | mempool_t *pool, int force) | |
200 | { | |
201 | struct bio *bio; | |
202 | int rw = bio_data_dir(*bio_orig); | |
203 | struct bio_vec *to, from; | |
204 | struct bvec_iter iter; | |
205 | unsigned i; | |
206 | ||
207 | if (force) | |
208 | goto bounce; | |
209 | bio_for_each_segment(from, *bio_orig, iter) | |
210 | if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q)) | |
211 | goto bounce; | |
212 | ||
213 | return; | |
214 | bounce: | |
215 | bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set); | |
216 | ||
217 | bio_for_each_segment_all(to, bio, i) { | |
218 | struct page *page = to->bv_page; | |
219 | ||
220 | if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force) | |
221 | continue; | |
222 | ||
223 | to->bv_page = mempool_alloc(pool, q->bounce_gfp); | |
224 | inc_zone_page_state(to->bv_page, NR_BOUNCE); | |
225 | ||
226 | if (rw == WRITE) { | |
227 | char *vto, *vfrom; | |
228 | ||
229 | flush_dcache_page(page); | |
230 | ||
231 | vto = page_address(to->bv_page) + to->bv_offset; | |
232 | vfrom = kmap_atomic(page) + to->bv_offset; | |
233 | memcpy(vto, vfrom, to->bv_len); | |
234 | kunmap_atomic(vfrom); | |
235 | } | |
236 | } | |
237 | ||
238 | trace_block_bio_bounce(q, *bio_orig); | |
239 | ||
240 | bio->bi_flags |= (1 << BIO_BOUNCED); | |
241 | ||
242 | if (pool == page_pool) { | |
243 | bio->bi_end_io = bounce_end_io_write; | |
244 | if (rw == READ) | |
245 | bio->bi_end_io = bounce_end_io_read; | |
246 | } else { | |
247 | bio->bi_end_io = bounce_end_io_write_isa; | |
248 | if (rw == READ) | |
249 | bio->bi_end_io = bounce_end_io_read_isa; | |
250 | } | |
251 | ||
252 | bio->bi_private = *bio_orig; | |
253 | *bio_orig = bio; | |
254 | } | |
255 | ||
256 | void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) | |
257 | { | |
258 | int must_bounce; | |
259 | mempool_t *pool; | |
260 | ||
261 | /* | |
262 | * Data-less bio, nothing to bounce | |
263 | */ | |
264 | if (!bio_has_data(*bio_orig)) | |
265 | return; | |
266 | ||
267 | must_bounce = must_snapshot_stable_pages(q, *bio_orig); | |
268 | ||
269 | /* | |
270 | * for non-isa bounce case, just check if the bounce pfn is equal | |
271 | * to or bigger than the highest pfn in the system -- in that case, | |
272 | * don't waste time iterating over bio segments | |
273 | */ | |
274 | if (!(q->bounce_gfp & GFP_DMA)) { | |
275 | if (queue_bounce_pfn(q) >= blk_max_pfn && !must_bounce) | |
276 | return; | |
277 | pool = page_pool; | |
278 | } else { | |
279 | BUG_ON(!isa_page_pool); | |
280 | pool = isa_page_pool; | |
281 | } | |
282 | ||
283 | /* | |
284 | * slow path | |
285 | */ | |
286 | __blk_queue_bounce(q, bio_orig, pool, must_bounce); | |
287 | } | |
288 | ||
289 | EXPORT_SYMBOL(blk_queue_bounce); |