aboutsummaryrefslogtreecommitdiff
path: root/mm/bounce.c
blob: bd1caaa582b80202330ceb3c428912a1d67436da (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
/* bounce buffer handling for block devices
 *
 * - Split from highmem.c
 */

#include <linux/mm.h>
#include <linux/module.h>
#include <linux/swap.h>
#include <linux/bio.h>
#include <linux/pagemap.h>
#include <linux/mempool.h>
#include <linux/blkdev.h>
#include <linux/init.h>
#include <linux/hash.h>
#include <linux/highmem.h>
#include <linux/blktrace_api.h>
#include <trace/block.h>
#include <asm/tlbflush.h>

#define POOL_SIZE	64
#define ISA_POOL_SIZE	16

static mempool_t *page_pool, *isa_page_pool;

#ifdef CONFIG_HIGHMEM
static __init int init_emergency_pool(void)
{
	struct sysinfo i;
	si_meminfo(&i);
	si_swapinfo(&i);

	if (!i.totalhigh)
		return 0;

	page_pool = mempool_create_page_pool(POOL_SIZE, 0);
	BUG_ON(!page_pool);
	printk("highmem bounce pool size: %d pages\n", POOL_SIZE);

	return 0;
}

__initcall(init_emergency_pool);

/*
 * highmem version, map in to vec
 */
static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
{
	unsigned long flags;
	unsigned char *vto;

	local_irq_save(flags);
	vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ);
	memcpy(vto + to->bv_offset, vfrom, to->bv_len);
	kunmap_atomic(vto, KM_BOUNCE_READ);
	local_irq_restore(flags);
}

#else /* CONFIG_HIGHMEM */

#define bounce_copy_vec(to, vfrom)	\
	memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)

#endif /* CONFIG_HIGHMEM */

/*
 * allocate pages in the DMA region for the ISA pool
 */
static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
{
	return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
}

/*
 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
 * as the max address, so check if the pool has already been created.
 */
int init_emergency_isa_pool(void)
{
	if (isa_page_pool)
		return 0;

	isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
				       mempool_free_pages, (void *) 0);
	BUG_ON(!isa_page_pool);

	printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
	return 0;
}

/*
 * Simple bounce buffer support for highmem pages. Depending on the
 * queue gfp mask set, *to may or may not be a highmem page. kmap it
 * always, it will do the Right Thing
 */
static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
{
	unsigned char *vfrom;
	struct bio_vec *tovec, *fromvec;
	int i;

	__bio_for_each_segment(tovec, to, i, 0) {
		fromvec = from->bi_io_vec + i;

		/*
		 * not bounced
		 */
		if (tovec->bv_page == fromvec->bv_page)
			continue;

		/*
		 * fromvec->bv_offset and fromvec->bv_len might have been
		 * modified by the block layer, so use the original copy,
		 * bounce_copy_vec already uses tovec->bv_len
		 */
		vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;

		flush_dcache_page(tovec->bv_page);
		bounce_copy_vec(tovec, vfrom);
	}
}

static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
{
	struct bio *bio_orig = bio->bi_private;
	struct bio_vec *bvec, *org_vec;
	int i;

	if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
		set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);

	/*
	 * free up bounce indirect pages used
	 */
	__bio_for_each_segment(bvec, bio, i, 0) {
		org_vec = bio_orig->bi_io_vec + i;
		if (bvec->bv_page == org_vec->bv_page)
			continue;

		dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
		mempool_free(bvec->bv_page, pool);
	}

	bio_endio(bio_orig, err);
	bio_put(bio);
}

static void bounce_end_io_write(struct bio *bio, int err)
{
	bounce_end_io(bio, page_pool, err);
}

static void bounce_end_io_write_isa(struct bio *bio, int err)
{

	bounce_end_io(bio, isa_page_pool, err);
}

static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
{
	struct bio *bio_orig = bio->bi_private;

	if (test_bit(BIO_UPTODATE, &bio->bi_flags))
		copy_to_high_bio_irq(bio_orig, bio);

	bounce_end_io(bio, pool, err);
}

static void bounce_end_io_read(struct bio *bio, int err)
{
	__bounce_end_io_read(bio, page_pool, err);
}

static void bounce_end_io_read_isa(struct bio *bio, int err)
{
	__bounce_end_io_read(bio, isa_page_pool, err);
}

static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
			       mempool_t *pool)
{
	struct page *page;
	struct bio *bio = NULL;
	int i, rw = bio_data_dir(*bio_orig);
	struct bio_vec *to, *from;

	bio_for_each_segment(from, *bio_orig, i) {
		page = from->bv_page;

		/*
		 * is destination page below bounce pfn?
		 */
		if (page_to_pfn(page) <= q->bounce_pfn)
			continue;

		/*
		 * irk, bounce it
		 */
		if (!bio)
			bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);

		to = bio->bi_io_vec + i;

		to->bv_page = mempool_alloc(pool, q->bounce_gfp);
		to->bv_len = from->bv_len;
		to->bv_offset = from->bv_offset;
		inc_zone_page_state(to->bv_page, NR_BOUNCE);

		if (rw == WRITE) {
			char *vto, *vfrom;

			flush_dcache_page(from->bv_page);
			vto = page_address(to->bv_page) + to->bv_offset;
			vfrom = kmap(from->bv_page) + from->bv_offset;
			memcpy(vto, vfrom, to->bv_len);
			kunmap(from->bv_page);
		}
	}

	/*
	 * no pages bounced
	 */
	if (!bio)
		return;

	trace_block_bio_bounce(q, *bio_orig);

	/*
	 * at least one page was bounced, fill in possible non-highmem
	 * pages
	 */
	__bio_for_each_segment(from, *bio_orig, i, 0) {
		to = bio_iovec_idx(bio, i);
		if (!to->bv_page) {
			to->bv_page = from->bv_page;
			to->bv_len = from->bv_len;
			to->bv_offset = from->bv_offset;
		}
	}

	bio->bi_bdev = (*bio_orig)->bi_bdev;
	bio->bi_flags |= (1 << BIO_BOUNCED);
	bio->bi_sector = (*bio_orig)->bi_sector;
	bio->bi_rw = (*bio_orig)->bi_rw;

	bio->bi_vcnt = (*bio_orig)->bi_vcnt;
	bio->bi_idx = (*bio_orig)->bi_idx;
	bio->bi_size = (*bio_orig)->bi_size;

	if (pool == page_pool) {
		bio->bi_end_io = bounce_end_io_write;
		if (rw == READ)
			bio->bi_end_io = bounce_end_io_read;
	} else {
		bio->bi_end_io = bounce_end_io_write_isa;
		if (rw == READ)
			bio->bi_end_io = bounce_end_io_read_isa;
	}

	bio->bi_private = *bio_orig;
	*bio_orig = bio;
}

void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
{
	mempool_t *pool;

	/*
	 * Data-less bio, nothing to bounce
	 */
	if (!bio_has_data(*bio_orig))
		return;

	/*
	 * for non-isa bounce case, just check if the bounce pfn is equal
	 * to or bigger than the highest pfn in the system -- in that case,
	 * don't waste time iterating over bio segments
	 */
	if (!(q->bounce_gfp & GFP_DMA)) {
		if (q->bounce_pfn >= blk_max_pfn)
			return;
		pool = page_pool;
	} else {
		BUG_ON(!isa_page_pool);
		pool = isa_page_pool;
	}

	/*
	 * slow path
	 */
	__blk_queue_bounce(q, bio_orig, pool);
}

EXPORT_SYMBOL(blk_queue_bounce);