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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 | #include "blk.h" | |
26 | ||
27 | #define POOL_SIZE 64 | |
28 | #define ISA_POOL_SIZE 16 | |
29 | ||
30 | static struct bio_set *bounce_bio_set, *bounce_bio_split; | |
31 | static mempool_t *page_pool, *isa_page_pool; | |
32 | ||
33 | #if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL) | |
34 | static __init int init_emergency_pool(void) | |
35 | { | |
36 | #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG) | |
37 | if (max_pfn <= max_low_pfn) | |
38 | return 0; | |
39 | #endif | |
40 | ||
41 | page_pool = mempool_create_page_pool(POOL_SIZE, 0); | |
42 | BUG_ON(!page_pool); | |
43 | pr_info("pool size: %d pages\n", POOL_SIZE); | |
44 | ||
45 | bounce_bio_set = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); | |
46 | BUG_ON(!bounce_bio_set); | |
47 | if (bioset_integrity_create(bounce_bio_set, BIO_POOL_SIZE)) | |
48 | BUG_ON(1); | |
49 | ||
50 | bounce_bio_split = bioset_create(BIO_POOL_SIZE, 0, 0); | |
51 | BUG_ON(!bounce_bio_split); | |
52 | ||
53 | return 0; | |
54 | } | |
55 | ||
56 | __initcall(init_emergency_pool); | |
57 | #endif | |
58 | ||
59 | #ifdef CONFIG_HIGHMEM | |
60 | /* | |
61 | * highmem version, map in to vec | |
62 | */ | |
63 | static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) | |
64 | { | |
65 | unsigned long flags; | |
66 | unsigned char *vto; | |
67 | ||
68 | local_irq_save(flags); | |
69 | vto = kmap_atomic(to->bv_page); | |
70 | memcpy(vto + to->bv_offset, vfrom, to->bv_len); | |
71 | kunmap_atomic(vto); | |
72 | local_irq_restore(flags); | |
73 | } | |
74 | ||
75 | #else /* CONFIG_HIGHMEM */ | |
76 | ||
77 | #define bounce_copy_vec(to, vfrom) \ | |
78 | memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) | |
79 | ||
80 | #endif /* CONFIG_HIGHMEM */ | |
81 | ||
82 | /* | |
83 | * allocate pages in the DMA region for the ISA pool | |
84 | */ | |
85 | static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data) | |
86 | { | |
87 | return mempool_alloc_pages(gfp_mask | GFP_DMA, data); | |
88 | } | |
89 | ||
90 | /* | |
91 | * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA | |
92 | * as the max address, so check if the pool has already been created. | |
93 | */ | |
94 | int init_emergency_isa_pool(void) | |
95 | { | |
96 | if (isa_page_pool) | |
97 | return 0; | |
98 | ||
99 | isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa, | |
100 | mempool_free_pages, (void *) 0); | |
101 | BUG_ON(!isa_page_pool); | |
102 | ||
103 | pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE); | |
104 | return 0; | |
105 | } | |
106 | ||
107 | /* | |
108 | * Simple bounce buffer support for highmem pages. Depending on the | |
109 | * queue gfp mask set, *to may or may not be a highmem page. kmap it | |
110 | * always, it will do the Right Thing | |
111 | */ | |
112 | static void copy_to_high_bio_irq(struct bio *to, struct bio *from) | |
113 | { | |
114 | unsigned char *vfrom; | |
115 | struct bio_vec tovec, *fromvec = from->bi_io_vec; | |
116 | struct bvec_iter iter; | |
117 | ||
118 | bio_for_each_segment(tovec, to, iter) { | |
119 | if (tovec.bv_page != fromvec->bv_page) { | |
120 | /* | |
121 | * fromvec->bv_offset and fromvec->bv_len might have | |
122 | * been modified by the block layer, so use the original | |
123 | * copy, bounce_copy_vec already uses tovec->bv_len | |
124 | */ | |
125 | vfrom = page_address(fromvec->bv_page) + | |
126 | tovec.bv_offset; | |
127 | ||
128 | bounce_copy_vec(&tovec, vfrom); | |
129 | flush_dcache_page(tovec.bv_page); | |
130 | } | |
131 | ||
132 | fromvec++; | |
133 | } | |
134 | } | |
135 | ||
136 | static void bounce_end_io(struct bio *bio, mempool_t *pool) | |
137 | { | |
138 | struct bio *bio_orig = bio->bi_private; | |
139 | struct bio_vec *bvec, *org_vec; | |
140 | int i; | |
141 | int start = bio_orig->bi_iter.bi_idx; | |
142 | ||
143 | /* | |
144 | * free up bounce indirect pages used | |
145 | */ | |
146 | bio_for_each_segment_all(bvec, bio, i) { | |
147 | org_vec = bio_orig->bi_io_vec + i + start; | |
148 | ||
149 | if (bvec->bv_page == org_vec->bv_page) | |
150 | continue; | |
151 | ||
152 | dec_zone_page_state(bvec->bv_page, NR_BOUNCE); | |
153 | mempool_free(bvec->bv_page, pool); | |
154 | } | |
155 | ||
156 | bio_orig->bi_status = bio->bi_status; | |
157 | bio_endio(bio_orig); | |
158 | bio_put(bio); | |
159 | } | |
160 | ||
161 | static void bounce_end_io_write(struct bio *bio) | |
162 | { | |
163 | bounce_end_io(bio, page_pool); | |
164 | } | |
165 | ||
166 | static void bounce_end_io_write_isa(struct bio *bio) | |
167 | { | |
168 | ||
169 | bounce_end_io(bio, isa_page_pool); | |
170 | } | |
171 | ||
172 | static void __bounce_end_io_read(struct bio *bio, mempool_t *pool) | |
173 | { | |
174 | struct bio *bio_orig = bio->bi_private; | |
175 | ||
176 | if (!bio->bi_status) | |
177 | copy_to_high_bio_irq(bio_orig, bio); | |
178 | ||
179 | bounce_end_io(bio, pool); | |
180 | } | |
181 | ||
182 | static void bounce_end_io_read(struct bio *bio) | |
183 | { | |
184 | __bounce_end_io_read(bio, page_pool); | |
185 | } | |
186 | ||
187 | static void bounce_end_io_read_isa(struct bio *bio) | |
188 | { | |
189 | __bounce_end_io_read(bio, isa_page_pool); | |
190 | } | |
191 | ||
192 | static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, | |
193 | mempool_t *pool) | |
194 | { | |
195 | struct bio *bio; | |
196 | int rw = bio_data_dir(*bio_orig); | |
197 | struct bio_vec *to, from; | |
198 | struct bvec_iter iter; | |
199 | unsigned i = 0; | |
200 | bool bounce = false; | |
201 | int sectors = 0; | |
202 | ||
203 | bio_for_each_segment(from, *bio_orig, iter) { | |
204 | if (i++ < BIO_MAX_PAGES) | |
205 | sectors += from.bv_len >> 9; | |
206 | if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn) | |
207 | bounce = true; | |
208 | } | |
209 | if (!bounce) | |
210 | return; | |
211 | ||
212 | if (sectors < bio_sectors(*bio_orig)) { | |
213 | bio = bio_split(*bio_orig, sectors, GFP_NOIO, bounce_bio_split); | |
214 | bio_chain(bio, *bio_orig); | |
215 | generic_make_request(*bio_orig); | |
216 | *bio_orig = bio; | |
217 | } | |
218 | bio = bio_clone_bioset(*bio_orig, GFP_NOIO, bounce_bio_set); | |
219 | ||
220 | bio_for_each_segment_all(to, bio, i) { | |
221 | struct page *page = to->bv_page; | |
222 | ||
223 | if (page_to_pfn(page) <= q->limits.bounce_pfn) | |
224 | continue; | |
225 | ||
226 | to->bv_page = mempool_alloc(pool, q->bounce_gfp); | |
227 | inc_zone_page_state(to->bv_page, NR_BOUNCE); | |
228 | ||
229 | if (rw == WRITE) { | |
230 | char *vto, *vfrom; | |
231 | ||
232 | flush_dcache_page(page); | |
233 | ||
234 | vto = page_address(to->bv_page) + to->bv_offset; | |
235 | vfrom = kmap_atomic(page) + to->bv_offset; | |
236 | memcpy(vto, vfrom, to->bv_len); | |
237 | kunmap_atomic(vfrom); | |
238 | } | |
239 | } | |
240 | ||
241 | trace_block_bio_bounce(q, *bio_orig); | |
242 | ||
243 | bio->bi_flags |= (1 << BIO_BOUNCED); | |
244 | ||
245 | if (pool == page_pool) { | |
246 | bio->bi_end_io = bounce_end_io_write; | |
247 | if (rw == READ) | |
248 | bio->bi_end_io = bounce_end_io_read; | |
249 | } else { | |
250 | bio->bi_end_io = bounce_end_io_write_isa; | |
251 | if (rw == READ) | |
252 | bio->bi_end_io = bounce_end_io_read_isa; | |
253 | } | |
254 | ||
255 | bio->bi_private = *bio_orig; | |
256 | *bio_orig = bio; | |
257 | } | |
258 | ||
259 | void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) | |
260 | { | |
261 | mempool_t *pool; | |
262 | ||
263 | /* | |
264 | * Data-less bio, nothing to bounce | |
265 | */ | |
266 | if (!bio_has_data(*bio_orig)) | |
267 | return; | |
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 (q->limits.bounce_pfn >= blk_max_pfn) | |
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); | |
287 | } |