1 /* bounce buffer handling for block devices
3 * - Split from highmem.c
7 #include <linux/module.h>
8 #include <linux/swap.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 <asm/tlbflush.h>
19 #include <trace/events/block.h>
22 #define ISA_POOL_SIZE 16
24 static mempool_t
*page_pool
, *isa_page_pool
;
27 static __init
int init_emergency_pool(void)
36 page_pool
= mempool_create_page_pool(POOL_SIZE
, 0);
38 printk("highmem bounce pool size: %d pages\n", POOL_SIZE
);
43 __initcall(init_emergency_pool
);
46 * highmem version, map in to vec
48 static void bounce_copy_vec(struct bio_vec
*to
, unsigned char *vfrom
)
53 local_irq_save(flags
);
54 vto
= kmap_atomic(to
->bv_page
, KM_BOUNCE_READ
);
55 memcpy(vto
+ to
->bv_offset
, vfrom
, to
->bv_len
);
56 kunmap_atomic(vto
, KM_BOUNCE_READ
);
57 local_irq_restore(flags
);
60 #else /* CONFIG_HIGHMEM */
62 #define bounce_copy_vec(to, vfrom) \
63 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
65 #endif /* CONFIG_HIGHMEM */
68 * allocate pages in the DMA region for the ISA pool
70 static void *mempool_alloc_pages_isa(gfp_t gfp_mask
, void *data
)
72 return mempool_alloc_pages(gfp_mask
| GFP_DMA
, data
);
76 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
77 * as the max address, so check if the pool has already been created.
79 int init_emergency_isa_pool(void)
84 isa_page_pool
= mempool_create(ISA_POOL_SIZE
, mempool_alloc_pages_isa
,
85 mempool_free_pages
, (void *) 0);
86 BUG_ON(!isa_page_pool
);
88 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE
);
93 * Simple bounce buffer support for highmem pages. Depending on the
94 * queue gfp mask set, *to may or may not be a highmem page. kmap it
95 * always, it will do the Right Thing
97 static void copy_to_high_bio_irq(struct bio
*to
, struct bio
*from
)
100 struct bio_vec
*tovec
, *fromvec
;
103 __bio_for_each_segment(tovec
, to
, i
, 0) {
104 fromvec
= from
->bi_io_vec
+ i
;
109 if (tovec
->bv_page
== fromvec
->bv_page
)
113 * fromvec->bv_offset and fromvec->bv_len might have been
114 * modified by the block layer, so use the original copy,
115 * bounce_copy_vec already uses tovec->bv_len
117 vfrom
= page_address(fromvec
->bv_page
) + tovec
->bv_offset
;
119 bounce_copy_vec(tovec
, vfrom
);
120 flush_dcache_page(tovec
->bv_page
);
124 static void bounce_end_io(struct bio
*bio
, mempool_t
*pool
, int err
)
126 struct bio
*bio_orig
= bio
->bi_private
;
127 struct bio_vec
*bvec
, *org_vec
;
130 if (test_bit(BIO_EOPNOTSUPP
, &bio
->bi_flags
))
131 set_bit(BIO_EOPNOTSUPP
, &bio_orig
->bi_flags
);
134 * free up bounce indirect pages used
136 __bio_for_each_segment(bvec
, bio
, i
, 0) {
137 org_vec
= bio_orig
->bi_io_vec
+ i
;
138 if (bvec
->bv_page
== org_vec
->bv_page
)
141 dec_zone_page_state(bvec
->bv_page
, NR_BOUNCE
);
142 mempool_free(bvec
->bv_page
, pool
);
145 bio_endio(bio_orig
, err
);
149 static void bounce_end_io_write(struct bio
*bio
, int err
)
151 bounce_end_io(bio
, page_pool
, err
);
154 static void bounce_end_io_write_isa(struct bio
*bio
, int err
)
157 bounce_end_io(bio
, isa_page_pool
, err
);
160 static void __bounce_end_io_read(struct bio
*bio
, mempool_t
*pool
, int err
)
162 struct bio
*bio_orig
= bio
->bi_private
;
164 if (test_bit(BIO_UPTODATE
, &bio
->bi_flags
))
165 copy_to_high_bio_irq(bio_orig
, bio
);
167 bounce_end_io(bio
, pool
, err
);
170 static void bounce_end_io_read(struct bio
*bio
, int err
)
172 __bounce_end_io_read(bio
, page_pool
, err
);
175 static void bounce_end_io_read_isa(struct bio
*bio
, int err
)
177 __bounce_end_io_read(bio
, isa_page_pool
, err
);
180 static void __blk_queue_bounce(struct request_queue
*q
, struct bio
**bio_orig
,
184 struct bio
*bio
= NULL
;
185 int i
, rw
= bio_data_dir(*bio_orig
);
186 struct bio_vec
*to
, *from
;
188 bio_for_each_segment(from
, *bio_orig
, i
) {
189 page
= from
->bv_page
;
192 * is destination page below bounce pfn?
194 if (page_to_pfn(page
) <= queue_bounce_pfn(q
))
201 unsigned int cnt
= (*bio_orig
)->bi_vcnt
;
203 bio
= bio_alloc(GFP_NOIO
, cnt
);
204 memset(bio
->bi_io_vec
, 0, cnt
* sizeof(struct bio_vec
));
208 to
= bio
->bi_io_vec
+ i
;
210 to
->bv_page
= mempool_alloc(pool
, q
->bounce_gfp
);
211 to
->bv_len
= from
->bv_len
;
212 to
->bv_offset
= from
->bv_offset
;
213 inc_zone_page_state(to
->bv_page
, NR_BOUNCE
);
218 flush_dcache_page(from
->bv_page
);
219 vto
= page_address(to
->bv_page
) + to
->bv_offset
;
220 vfrom
= kmap(from
->bv_page
) + from
->bv_offset
;
221 memcpy(vto
, vfrom
, to
->bv_len
);
222 kunmap(from
->bv_page
);
232 trace_block_bio_bounce(q
, *bio_orig
);
235 * at least one page was bounced, fill in possible non-highmem
238 __bio_for_each_segment(from
, *bio_orig
, i
, 0) {
239 to
= bio_iovec_idx(bio
, i
);
241 to
->bv_page
= from
->bv_page
;
242 to
->bv_len
= from
->bv_len
;
243 to
->bv_offset
= from
->bv_offset
;
247 bio
->bi_bdev
= (*bio_orig
)->bi_bdev
;
248 bio
->bi_flags
|= (1 << BIO_BOUNCED
);
249 bio
->bi_sector
= (*bio_orig
)->bi_sector
;
250 bio
->bi_rw
= (*bio_orig
)->bi_rw
;
252 bio
->bi_vcnt
= (*bio_orig
)->bi_vcnt
;
253 bio
->bi_idx
= (*bio_orig
)->bi_idx
;
254 bio
->bi_size
= (*bio_orig
)->bi_size
;
256 if (pool
== page_pool
) {
257 bio
->bi_end_io
= bounce_end_io_write
;
259 bio
->bi_end_io
= bounce_end_io_read
;
261 bio
->bi_end_io
= bounce_end_io_write_isa
;
263 bio
->bi_end_io
= bounce_end_io_read_isa
;
266 bio
->bi_private
= *bio_orig
;
270 void blk_queue_bounce(struct request_queue
*q
, struct bio
**bio_orig
)
275 * Data-less bio, nothing to bounce
277 if (!bio_has_data(*bio_orig
))
281 * for non-isa bounce case, just check if the bounce pfn is equal
282 * to or bigger than the highest pfn in the system -- in that case,
283 * don't waste time iterating over bio segments
285 if (!(q
->bounce_gfp
& GFP_DMA
)) {
286 if (queue_bounce_pfn(q
) >= blk_max_pfn
)
290 BUG_ON(!isa_page_pool
);
291 pool
= isa_page_pool
;
297 __blk_queue_bounce(q
, bio_orig
, pool
);
300 EXPORT_SYMBOL(blk_queue_bounce
);
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