1 // SPDX-License-Identifier: GPL-2.0
2 /* bounce buffer handling for block devices
3 *
4 * - Split from highmem.c
5 */
6
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9 #include <linux/mm.h>
10 #include <linux/export.h>
11 #include <linux/swap.h>
12 #include <linux/gfp.h>
13 #include <linux/bio.h>
14 #include <linux/pagemap.h>
15 #include <linux/mempool.h>
16 #include <linux/blkdev.h>
17 #include <linux/backing-dev.h>
18 #include <linux/init.h>
19 #include <linux/hash.h>
20 #include <linux/highmem.h>
21 #include <linux/bootmem.h>
22 #include <linux/printk.h>
23 #include <asm/tlbflush.h>
24
25 #include <trace/events/block.h>
26 #include "blk.h"
27
28 #define POOL_SIZE 64
29 #define ISA_POOL_SIZE 16
30
31 static struct bio_set bounce_bio_set, bounce_bio_split;
32 static mempool_t page_pool, isa_page_pool;
33
34 #if defined(CONFIG_HIGHMEM)
init_emergency_pool(void)35 static __init int init_emergency_pool(void)
36 {
37 int ret;
38 #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG)
39 if (max_pfn <= max_low_pfn)
40 return 0;
41 #endif
42
43 ret = mempool_init_page_pool(&page_pool, POOL_SIZE, 0);
44 BUG_ON(ret);
45 pr_info("pool size: %d pages\n", POOL_SIZE);
46
47 ret = bioset_init(&bounce_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
48 BUG_ON(ret);
49 if (bioset_integrity_create(&bounce_bio_set, BIO_POOL_SIZE))
50 BUG_ON(1);
51
52 ret = bioset_init(&bounce_bio_split, BIO_POOL_SIZE, 0, 0);
53 BUG_ON(ret);
54
55 return 0;
56 }
57
58 __initcall(init_emergency_pool);
59 #endif
60
61 #ifdef CONFIG_HIGHMEM
62 /*
63 * highmem version, map in to vec
64 */
bounce_copy_vec(struct bio_vec * to,unsigned char * vfrom)65 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
66 {
67 unsigned char *vto;
68
69 vto = kmap_atomic(to->bv_page);
70 memcpy(vto + to->bv_offset, vfrom, to->bv_len);
71 kunmap_atomic(vto);
72 }
73
74 #else /* CONFIG_HIGHMEM */
75
76 #define bounce_copy_vec(to, vfrom) \
77 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
78
79 #endif /* CONFIG_HIGHMEM */
80
81 /*
82 * allocate pages in the DMA region for the ISA pool
83 */
mempool_alloc_pages_isa(gfp_t gfp_mask,void * data)84 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
85 {
86 return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
87 }
88
89 /*
90 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
91 * as the max address, so check if the pool has already been created.
92 */
init_emergency_isa_pool(void)93 int init_emergency_isa_pool(void)
94 {
95 int ret;
96
97 if (mempool_initialized(&isa_page_pool))
98 return 0;
99
100 ret = mempool_init(&isa_page_pool, ISA_POOL_SIZE, mempool_alloc_pages_isa,
101 mempool_free_pages, (void *) 0);
102 BUG_ON(ret);
103
104 pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE);
105 return 0;
106 }
107
108 /*
109 * Simple bounce buffer support for highmem pages. Depending on the
110 * queue gfp mask set, *to may or may not be a highmem page. kmap it
111 * always, it will do the Right Thing
112 */
copy_to_high_bio_irq(struct bio * to,struct bio * from)113 static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
114 {
115 unsigned char *vfrom;
116 struct bio_vec tovec, fromvec;
117 struct bvec_iter iter;
118 /*
119 * The bio of @from is created by bounce, so we can iterate
120 * its bvec from start to end, but the @from->bi_iter can't be
121 * trusted because it might be changed by splitting.
122 */
123 struct bvec_iter from_iter = BVEC_ITER_ALL_INIT;
124
125 bio_for_each_segment(tovec, to, iter) {
126 fromvec = bio_iter_iovec(from, from_iter);
127 if (tovec.bv_page != fromvec.bv_page) {
128 /*
129 * fromvec->bv_offset and fromvec->bv_len might have
130 * been modified by the block layer, so use the original
131 * copy, bounce_copy_vec already uses tovec->bv_len
132 */
133 vfrom = page_address(fromvec.bv_page) +
134 tovec.bv_offset;
135
136 bounce_copy_vec(&tovec, vfrom);
137 flush_dcache_page(tovec.bv_page);
138 }
139 bio_advance_iter(from, &from_iter, tovec.bv_len);
140 }
141 }
142
bounce_end_io(struct bio * bio,mempool_t * pool)143 static void bounce_end_io(struct bio *bio, mempool_t *pool)
144 {
145 struct bio *bio_orig = bio->bi_private;
146 struct bio_vec *bvec, orig_vec;
147 int i;
148 struct bvec_iter orig_iter = bio_orig->bi_iter;
149
150 /*
151 * free up bounce indirect pages used
152 */
153 bio_for_each_segment_all(bvec, bio, i) {
154 orig_vec = bio_iter_iovec(bio_orig, orig_iter);
155 if (bvec->bv_page != orig_vec.bv_page) {
156 dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
157 mempool_free(bvec->bv_page, pool);
158 }
159 bio_advance_iter(bio_orig, &orig_iter, orig_vec.bv_len);
160 }
161
162 bio_orig->bi_status = bio->bi_status;
163 bio_endio(bio_orig);
164 bio_put(bio);
165 }
166
bounce_end_io_write(struct bio * bio)167 static void bounce_end_io_write(struct bio *bio)
168 {
169 bounce_end_io(bio, &page_pool);
170 }
171
bounce_end_io_write_isa(struct bio * bio)172 static void bounce_end_io_write_isa(struct bio *bio)
173 {
174
175 bounce_end_io(bio, &isa_page_pool);
176 }
177
__bounce_end_io_read(struct bio * bio,mempool_t * pool)178 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool)
179 {
180 struct bio *bio_orig = bio->bi_private;
181
182 if (!bio->bi_status)
183 copy_to_high_bio_irq(bio_orig, bio);
184
185 bounce_end_io(bio, pool);
186 }
187
bounce_end_io_read(struct bio * bio)188 static void bounce_end_io_read(struct bio *bio)
189 {
190 __bounce_end_io_read(bio, &page_pool);
191 }
192
bounce_end_io_read_isa(struct bio * bio)193 static void bounce_end_io_read_isa(struct bio *bio)
194 {
195 __bounce_end_io_read(bio, &isa_page_pool);
196 }
197
bounce_clone_bio(struct bio * bio_src,gfp_t gfp_mask,struct bio_set * bs)198 static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,
199 struct bio_set *bs)
200 {
201 struct bvec_iter iter;
202 struct bio_vec bv;
203 struct bio *bio;
204
205 /*
206 * Pre immutable biovecs, __bio_clone() used to just do a memcpy from
207 * bio_src->bi_io_vec to bio->bi_io_vec.
208 *
209 * We can't do that anymore, because:
210 *
211 * - The point of cloning the biovec is to produce a bio with a biovec
212 * the caller can modify: bi_idx and bi_bvec_done should be 0.
213 *
214 * - The original bio could've had more than BIO_MAX_PAGES biovecs; if
215 * we tried to clone the whole thing bio_alloc_bioset() would fail.
216 * But the clone should succeed as long as the number of biovecs we
217 * actually need to allocate is fewer than BIO_MAX_PAGES.
218 *
219 * - Lastly, bi_vcnt should not be looked at or relied upon by code
220 * that does not own the bio - reason being drivers don't use it for
221 * iterating over the biovec anymore, so expecting it to be kept up
222 * to date (i.e. for clones that share the parent biovec) is just
223 * asking for trouble and would force extra work on
224 * __bio_clone_fast() anyways.
225 */
226
227 bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
228 if (!bio)
229 return NULL;
230 bio->bi_disk = bio_src->bi_disk;
231 bio->bi_opf = bio_src->bi_opf;
232 bio->bi_write_hint = bio_src->bi_write_hint;
233 bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;
234 bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;
235
236 switch (bio_op(bio)) {
237 case REQ_OP_DISCARD:
238 case REQ_OP_SECURE_ERASE:
239 case REQ_OP_WRITE_ZEROES:
240 break;
241 case REQ_OP_WRITE_SAME:
242 bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
243 break;
244 default:
245 bio_for_each_segment(bv, bio_src, iter)
246 bio->bi_io_vec[bio->bi_vcnt++] = bv;
247 break;
248 }
249
250 if (bio_integrity(bio_src)) {
251 int ret;
252
253 ret = bio_integrity_clone(bio, bio_src, gfp_mask);
254 if (ret < 0) {
255 bio_put(bio);
256 return NULL;
257 }
258 }
259
260 bio_clone_blkcg_association(bio, bio_src);
261
262 return bio;
263 }
264
__blk_queue_bounce(struct request_queue * q,struct bio ** bio_orig,mempool_t * pool)265 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
266 mempool_t *pool)
267 {
268 struct bio *bio;
269 int rw = bio_data_dir(*bio_orig);
270 struct bio_vec *to, from;
271 struct bvec_iter iter;
272 unsigned i = 0;
273 bool bounce = false;
274 int sectors = 0;
275 bool passthrough = bio_is_passthrough(*bio_orig);
276
277 bio_for_each_segment(from, *bio_orig, iter) {
278 if (i++ < BIO_MAX_PAGES)
279 sectors += from.bv_len >> 9;
280 if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn)
281 bounce = true;
282 }
283 if (!bounce)
284 return;
285
286 if (!passthrough && sectors < bio_sectors(*bio_orig)) {
287 bio = bio_split(*bio_orig, sectors, GFP_NOIO, &bounce_bio_split);
288 bio_chain(bio, *bio_orig);
289 generic_make_request(*bio_orig);
290 *bio_orig = bio;
291 }
292 bio = bounce_clone_bio(*bio_orig, GFP_NOIO, passthrough ? NULL :
293 &bounce_bio_set);
294
295 bio_for_each_segment_all(to, bio, i) {
296 struct page *page = to->bv_page;
297
298 if (page_to_pfn(page) <= q->limits.bounce_pfn)
299 continue;
300
301 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
302 inc_zone_page_state(to->bv_page, NR_BOUNCE);
303
304 if (rw == WRITE) {
305 char *vto, *vfrom;
306
307 flush_dcache_page(page);
308
309 vto = page_address(to->bv_page) + to->bv_offset;
310 vfrom = kmap_atomic(page) + to->bv_offset;
311 memcpy(vto, vfrom, to->bv_len);
312 kunmap_atomic(vfrom);
313 }
314 }
315
316 trace_block_bio_bounce(q, *bio_orig);
317
318 bio->bi_flags |= (1 << BIO_BOUNCED);
319
320 if (pool == &page_pool) {
321 bio->bi_end_io = bounce_end_io_write;
322 if (rw == READ)
323 bio->bi_end_io = bounce_end_io_read;
324 } else {
325 bio->bi_end_io = bounce_end_io_write_isa;
326 if (rw == READ)
327 bio->bi_end_io = bounce_end_io_read_isa;
328 }
329
330 bio->bi_private = *bio_orig;
331 *bio_orig = bio;
332 }
333
blk_queue_bounce(struct request_queue * q,struct bio ** bio_orig)334 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
335 {
336 mempool_t *pool;
337
338 /*
339 * Data-less bio, nothing to bounce
340 */
341 if (!bio_has_data(*bio_orig))
342 return;
343
344 /*
345 * for non-isa bounce case, just check if the bounce pfn is equal
346 * to or bigger than the highest pfn in the system -- in that case,
347 * don't waste time iterating over bio segments
348 */
349 if (!(q->bounce_gfp & GFP_DMA)) {
350 if (q->limits.bounce_pfn >= blk_max_pfn)
351 return;
352 pool = &page_pool;
353 } else {
354 BUG_ON(!mempool_initialized(&isa_page_pool));
355 pool = &isa_page_pool;
356 }
357
358 /*
359 * slow path
360 */
361 __blk_queue_bounce(q, bio_orig, pool);
362 }
363
