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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 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);