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