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David Howells831058d2006-08-29 19:06:00 +01001/* bounce buffer handling for block devices
2 *
3 * - Split from highmem.c
4 */
5
6#include <linux/mm.h>
7#include <linux/module.h>
8#include <linux/swap.h>
9#include <linux/bio.h>
10#include <linux/pagemap.h>
11#include <linux/mempool.h>
12#include <linux/blkdev.h>
13#include <linux/init.h>
14#include <linux/hash.h>
15#include <linux/highmem.h>
16#include <linux/blktrace_api.h>
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +010017#include <trace/block.h>
David Howells831058d2006-08-29 19:06:00 +010018#include <asm/tlbflush.h>
19
20#define POOL_SIZE 64
21#define ISA_POOL_SIZE 16
22
23static mempool_t *page_pool, *isa_page_pool;
24
25#ifdef CONFIG_HIGHMEM
26static __init int init_emergency_pool(void)
27{
28 struct sysinfo i;
29 si_meminfo(&i);
30 si_swapinfo(&i);
31
32 if (!i.totalhigh)
33 return 0;
34
35 page_pool = mempool_create_page_pool(POOL_SIZE, 0);
36 BUG_ON(!page_pool);
37 printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
38
39 return 0;
40}
41
42__initcall(init_emergency_pool);
43
44/*
45 * highmem version, map in to vec
46 */
47static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
48{
49 unsigned long flags;
50 unsigned char *vto;
51
52 local_irq_save(flags);
53 vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ);
54 memcpy(vto + to->bv_offset, vfrom, to->bv_len);
55 kunmap_atomic(vto, KM_BOUNCE_READ);
56 local_irq_restore(flags);
57}
58
59#else /* CONFIG_HIGHMEM */
60
61#define bounce_copy_vec(to, vfrom) \
62 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
63
64#endif /* CONFIG_HIGHMEM */
65
66/*
67 * allocate pages in the DMA region for the ISA pool
68 */
69static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
70{
71 return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
72}
73
74/*
75 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
76 * as the max address, so check if the pool has already been created.
77 */
78int init_emergency_isa_pool(void)
79{
80 if (isa_page_pool)
81 return 0;
82
83 isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
84 mempool_free_pages, (void *) 0);
85 BUG_ON(!isa_page_pool);
86
87 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
88 return 0;
89}
90
91/*
92 * Simple bounce buffer support for highmem pages. Depending on the
93 * queue gfp mask set, *to may or may not be a highmem page. kmap it
94 * always, it will do the Right Thing
95 */
96static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
97{
98 unsigned char *vfrom;
99 struct bio_vec *tovec, *fromvec;
100 int i;
101
102 __bio_for_each_segment(tovec, to, i, 0) {
103 fromvec = from->bi_io_vec + i;
104
105 /*
106 * not bounced
107 */
108 if (tovec->bv_page == fromvec->bv_page)
109 continue;
110
111 /*
112 * fromvec->bv_offset and fromvec->bv_len might have been
113 * modified by the block layer, so use the original copy,
114 * bounce_copy_vec already uses tovec->bv_len
115 */
116 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
117
118 flush_dcache_page(tovec->bv_page);
119 bounce_copy_vec(tovec, vfrom);
120 }
121}
122
123static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
124{
125 struct bio *bio_orig = bio->bi_private;
126 struct bio_vec *bvec, *org_vec;
127 int i;
128
129 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
130 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
131
132 /*
133 * free up bounce indirect pages used
134 */
135 __bio_for_each_segment(bvec, bio, i, 0) {
136 org_vec = bio_orig->bi_io_vec + i;
137 if (bvec->bv_page == org_vec->bv_page)
138 continue;
139
140 dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
141 mempool_free(bvec->bv_page, pool);
142 }
143
NeilBrown6712ecf2007-09-27 12:47:43 +0200144 bio_endio(bio_orig, err);
David Howells831058d2006-08-29 19:06:00 +0100145 bio_put(bio);
146}
147
NeilBrown6712ecf2007-09-27 12:47:43 +0200148static void bounce_end_io_write(struct bio *bio, int err)
David Howells831058d2006-08-29 19:06:00 +0100149{
David Howells831058d2006-08-29 19:06:00 +0100150 bounce_end_io(bio, page_pool, err);
David Howells831058d2006-08-29 19:06:00 +0100151}
152
NeilBrown6712ecf2007-09-27 12:47:43 +0200153static void bounce_end_io_write_isa(struct bio *bio, int err)
David Howells831058d2006-08-29 19:06:00 +0100154{
David Howells831058d2006-08-29 19:06:00 +0100155
156 bounce_end_io(bio, isa_page_pool, err);
David Howells831058d2006-08-29 19:06:00 +0100157}
158
159static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
160{
161 struct bio *bio_orig = bio->bi_private;
162
163 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
164 copy_to_high_bio_irq(bio_orig, bio);
165
166 bounce_end_io(bio, pool, err);
167}
168
NeilBrown6712ecf2007-09-27 12:47:43 +0200169static void bounce_end_io_read(struct bio *bio, int err)
David Howells831058d2006-08-29 19:06:00 +0100170{
David Howells831058d2006-08-29 19:06:00 +0100171 __bounce_end_io_read(bio, page_pool, err);
David Howells831058d2006-08-29 19:06:00 +0100172}
173
NeilBrown6712ecf2007-09-27 12:47:43 +0200174static void bounce_end_io_read_isa(struct bio *bio, int err)
David Howells831058d2006-08-29 19:06:00 +0100175{
David Howells831058d2006-08-29 19:06:00 +0100176 __bounce_end_io_read(bio, isa_page_pool, err);
David Howells831058d2006-08-29 19:06:00 +0100177}
178
Jens Axboe165125e2007-07-24 09:28:11 +0200179static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
David Howells831058d2006-08-29 19:06:00 +0100180 mempool_t *pool)
181{
182 struct page *page;
183 struct bio *bio = NULL;
184 int i, rw = bio_data_dir(*bio_orig);
185 struct bio_vec *to, *from;
186
187 bio_for_each_segment(from, *bio_orig, i) {
188 page = from->bv_page;
189
190 /*
191 * is destination page below bounce pfn?
192 */
Vasily Tarasovf772b3d2007-03-27 08:52:47 +0200193 if (page_to_pfn(page) <= q->bounce_pfn)
David Howells831058d2006-08-29 19:06:00 +0100194 continue;
195
196 /*
197 * irk, bounce it
198 */
199 if (!bio)
200 bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);
201
202 to = bio->bi_io_vec + i;
203
204 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
205 to->bv_len = from->bv_len;
206 to->bv_offset = from->bv_offset;
207 inc_zone_page_state(to->bv_page, NR_BOUNCE);
208
209 if (rw == WRITE) {
210 char *vto, *vfrom;
211
212 flush_dcache_page(from->bv_page);
213 vto = page_address(to->bv_page) + to->bv_offset;
214 vfrom = kmap(from->bv_page) + from->bv_offset;
215 memcpy(vto, vfrom, to->bv_len);
216 kunmap(from->bv_page);
217 }
218 }
219
220 /*
221 * no pages bounced
222 */
223 if (!bio)
224 return;
225
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +0100226 trace_block_bio_bounce(q, *bio_orig);
Jens Axboec43a5082007-01-12 12:20:26 +0100227
David Howells831058d2006-08-29 19:06:00 +0100228 /*
229 * at least one page was bounced, fill in possible non-highmem
230 * pages
231 */
232 __bio_for_each_segment(from, *bio_orig, i, 0) {
233 to = bio_iovec_idx(bio, i);
234 if (!to->bv_page) {
235 to->bv_page = from->bv_page;
236 to->bv_len = from->bv_len;
237 to->bv_offset = from->bv_offset;
238 }
239 }
240
241 bio->bi_bdev = (*bio_orig)->bi_bdev;
242 bio->bi_flags |= (1 << BIO_BOUNCED);
243 bio->bi_sector = (*bio_orig)->bi_sector;
244 bio->bi_rw = (*bio_orig)->bi_rw;
245
246 bio->bi_vcnt = (*bio_orig)->bi_vcnt;
247 bio->bi_idx = (*bio_orig)->bi_idx;
248 bio->bi_size = (*bio_orig)->bi_size;
249
250 if (pool == page_pool) {
251 bio->bi_end_io = bounce_end_io_write;
252 if (rw == READ)
253 bio->bi_end_io = bounce_end_io_read;
254 } else {
255 bio->bi_end_io = bounce_end_io_write_isa;
256 if (rw == READ)
257 bio->bi_end_io = bounce_end_io_read_isa;
258 }
259
260 bio->bi_private = *bio_orig;
261 *bio_orig = bio;
262}
263
Jens Axboe165125e2007-07-24 09:28:11 +0200264void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
David Howells831058d2006-08-29 19:06:00 +0100265{
266 mempool_t *pool;
267
268 /*
Jens Axboebf2de6f2007-09-27 13:01:25 +0200269 * Data-less bio, nothing to bounce
270 */
Jens Axboe36144072008-08-14 13:12:15 +0200271 if (!bio_has_data(*bio_orig))
Jens Axboebf2de6f2007-09-27 13:01:25 +0200272 return;
273
274 /*
David Howells831058d2006-08-29 19:06:00 +0100275 * for non-isa bounce case, just check if the bounce pfn is equal
276 * to or bigger than the highest pfn in the system -- in that case,
277 * don't waste time iterating over bio segments
278 */
279 if (!(q->bounce_gfp & GFP_DMA)) {
280 if (q->bounce_pfn >= blk_max_pfn)
281 return;
282 pool = page_pool;
283 } else {
284 BUG_ON(!isa_page_pool);
285 pool = isa_page_pool;
286 }
287
David Howells831058d2006-08-29 19:06:00 +0100288 /*
289 * slow path
290 */
291 __blk_queue_bounce(q, bio_orig, pool);
292}
293
294EXPORT_SYMBOL(blk_queue_bounce);