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