blob: 1cb5dd3a5da1e7bf834f229d2c8776bbcb65a3d4
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 | int start = bio_orig->bi_iter.bi_idx; |
132 | |
133 | /* |
134 | * free up bounce indirect pages used |
135 | */ |
136 | bio_for_each_segment_all(bvec, bio, i) { |
137 | org_vec = bio_orig->bi_io_vec + i + start; |
138 | |
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_orig->bi_error = bio->bi_error; |
147 | bio_endio(bio_orig); |
148 | bio_put(bio); |
149 | } |
150 | |
151 | static void bounce_end_io_write(struct bio *bio) |
152 | { |
153 | bounce_end_io(bio, page_pool); |
154 | } |
155 | |
156 | static void bounce_end_io_write_isa(struct bio *bio) |
157 | { |
158 | |
159 | bounce_end_io(bio, isa_page_pool); |
160 | } |
161 | |
162 | static void __bounce_end_io_read(struct bio *bio, mempool_t *pool) |
163 | { |
164 | struct bio *bio_orig = bio->bi_private; |
165 | |
166 | if (!bio->bi_error) |
167 | copy_to_high_bio_irq(bio_orig, bio); |
168 | |
169 | bounce_end_io(bio, pool); |
170 | } |
171 | |
172 | static void bounce_end_io_read(struct bio *bio) |
173 | { |
174 | __bounce_end_io_read(bio, page_pool); |
175 | } |
176 | |
177 | static void bounce_end_io_read_isa(struct bio *bio) |
178 | { |
179 | __bounce_end_io_read(bio, isa_page_pool); |
180 | } |
181 | |
182 | static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, |
183 | mempool_t *pool) |
184 | { |
185 | struct bio *bio; |
186 | int rw = bio_data_dir(*bio_orig); |
187 | struct bio_vec *to, from; |
188 | struct bvec_iter iter; |
189 | unsigned i; |
190 | |
191 | bio_for_each_segment(from, *bio_orig, iter) |
192 | if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q)) |
193 | goto bounce; |
194 | |
195 | return; |
196 | bounce: |
197 | bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set); |
198 | |
199 | bio_for_each_segment_all(to, bio, i) { |
200 | struct page *page = to->bv_page; |
201 | |
202 | if (page_to_pfn(page) <= queue_bounce_pfn(q)) |
203 | continue; |
204 | |
205 | to->bv_page = mempool_alloc(pool, q->bounce_gfp); |
206 | inc_zone_page_state(to->bv_page, NR_BOUNCE); |
207 | |
208 | if (rw == WRITE) { |
209 | char *vto, *vfrom; |
210 | |
211 | flush_dcache_page(page); |
212 | |
213 | vto = page_address(to->bv_page) + to->bv_offset; |
214 | vfrom = kmap_atomic(page) + to->bv_offset; |
215 | memcpy(vto, vfrom, to->bv_len); |
216 | kunmap_atomic(vfrom); |
217 | } |
218 | } |
219 | |
220 | trace_block_bio_bounce(q, *bio_orig); |
221 | |
222 | bio->bi_flags |= (1 << BIO_BOUNCED); |
223 | |
224 | if (pool == page_pool) { |
225 | bio->bi_end_io = bounce_end_io_write; |
226 | if (rw == READ) |
227 | bio->bi_end_io = bounce_end_io_read; |
228 | } else { |
229 | bio->bi_end_io = bounce_end_io_write_isa; |
230 | if (rw == READ) |
231 | bio->bi_end_io = bounce_end_io_read_isa; |
232 | } |
233 | |
234 | bio->bi_private = *bio_orig; |
235 | *bio_orig = bio; |
236 | } |
237 | |
238 | void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) |
239 | { |
240 | mempool_t *pool; |
241 | |
242 | /* |
243 | * Data-less bio, nothing to bounce |
244 | */ |
245 | if (!bio_has_data(*bio_orig)) |
246 | return; |
247 | |
248 | /* |
249 | * for non-isa bounce case, just check if the bounce pfn is equal |
250 | * to or bigger than the highest pfn in the system -- in that case, |
251 | * don't waste time iterating over bio segments |
252 | */ |
253 | if (!(q->bounce_gfp & GFP_DMA)) { |
254 | if (queue_bounce_pfn(q) >= blk_max_pfn) |
255 | return; |
256 | pool = page_pool; |
257 | } else { |
258 | BUG_ON(!isa_page_pool); |
259 | pool = isa_page_pool; |
260 | } |
261 | |
262 | /* |
263 | * slow path |
264 | */ |
265 | __blk_queue_bounce(q, bio_orig, pool); |
266 | } |
267 | |
268 | EXPORT_SYMBOL(blk_queue_bounce); |
269 |