1 /* bounce buffer handling for block devices
3 * - Split from highmem.c
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/export.h>
10 #include <linux/swap.h>
11 #include <linux/gfp.h>
12 #include <linux/bio.h>
13 #include <linux/pagemap.h>
14 #include <linux/mempool.h>
15 #include <linux/blkdev.h>
16 #include <linux/backing-dev.h>
17 #include <linux/init.h>
18 #include <linux/hash.h>
19 #include <linux/highmem.h>
20 #include <linux/bootmem.h>
21 #include <linux/printk.h>
22 #include <asm/tlbflush.h>
24 #include <trace/events/block.h>
27 #define ISA_POOL_SIZE 16
29 static mempool_t
*page_pool
, *isa_page_pool
;
31 #if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL)
32 static __init
int init_emergency_pool(void)
34 #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG)
35 if (max_pfn
<= max_low_pfn
)
39 page_pool
= mempool_create_page_pool(POOL_SIZE
, 0);
41 pr_info("pool size: %d pages\n", POOL_SIZE
);
46 __initcall(init_emergency_pool
);
51 * highmem version, map in to vec
53 static void bounce_copy_vec(struct bio_vec
*to
, unsigned char *vfrom
)
58 local_irq_save(flags
);
59 vto
= kmap_atomic(to
->bv_page
);
60 memcpy(vto
+ to
->bv_offset
, vfrom
, to
->bv_len
);
62 local_irq_restore(flags
);
65 #else /* CONFIG_HIGHMEM */
67 #define bounce_copy_vec(to, vfrom) \
68 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
70 #endif /* CONFIG_HIGHMEM */
73 * allocate pages in the DMA region for the ISA pool
75 static void *mempool_alloc_pages_isa(gfp_t gfp_mask
, void *data
)
77 return mempool_alloc_pages(gfp_mask
| GFP_DMA
, data
);
81 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
82 * as the max address, so check if the pool has already been created.
84 int init_emergency_isa_pool(void)
89 isa_page_pool
= mempool_create(ISA_POOL_SIZE
, mempool_alloc_pages_isa
,
90 mempool_free_pages
, (void *) 0);
91 BUG_ON(!isa_page_pool
);
93 pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE
);
98 * Simple bounce buffer support for highmem pages. Depending on the
99 * queue gfp mask set, *to may or may not be a highmem page. kmap it
100 * always, it will do the Right Thing
102 static void copy_to_high_bio_irq(struct bio
*to
, struct bio
*from
)
104 unsigned char *vfrom
;
105 struct bio_vec tovec
, *fromvec
= from
->bi_io_vec
;
106 struct bvec_iter iter
;
108 bio_for_each_segment(tovec
, to
, iter
) {
109 if (tovec
.bv_page
!= fromvec
->bv_page
) {
111 * fromvec->bv_offset and fromvec->bv_len might have
112 * been modified by the block layer, so use the original
113 * copy, bounce_copy_vec already uses tovec->bv_len
115 vfrom
= page_address(fromvec
->bv_page
) +
118 bounce_copy_vec(&tovec
, vfrom
);
119 flush_dcache_page(tovec
.bv_page
);
126 static void bounce_end_io(struct bio
*bio
, mempool_t
*pool
)
128 struct bio
*bio_orig
= bio
->bi_private
;
129 struct bio_vec
*bvec
, *org_vec
;
133 * free up bounce indirect pages used
135 bio_for_each_segment_all(bvec
, bio
, i
) {
136 org_vec
= bio_orig
->bi_io_vec
+ i
;
137 if (bvec
->bv_page
== org_vec
->bv_page
)
140 dec_zone_page_state(bvec
->bv_page
, NR_BOUNCE
);
141 mempool_free(bvec
->bv_page
, pool
);
144 bio_orig
->bi_error
= bio
->bi_error
;
149 static void bounce_end_io_write(struct bio
*bio
)
151 bounce_end_io(bio
, page_pool
);
154 static void bounce_end_io_write_isa(struct bio
*bio
)
157 bounce_end_io(bio
, isa_page_pool
);
160 static void __bounce_end_io_read(struct bio
*bio
, mempool_t
*pool
)
162 struct bio
*bio_orig
= bio
->bi_private
;
165 copy_to_high_bio_irq(bio_orig
, bio
);
167 bounce_end_io(bio
, pool
);
170 static void bounce_end_io_read(struct bio
*bio
)
172 __bounce_end_io_read(bio
, page_pool
);
175 static void bounce_end_io_read_isa(struct bio
*bio
)
177 __bounce_end_io_read(bio
, isa_page_pool
);
180 static void __blk_queue_bounce(struct request_queue
*q
, struct bio
**bio_orig
,
184 int rw
= bio_data_dir(*bio_orig
);
185 struct bio_vec
*to
, from
;
186 struct bvec_iter iter
;
189 bio_for_each_segment(from
, *bio_orig
, iter
)
190 if (page_to_pfn(from
.bv_page
) > queue_bounce_pfn(q
))
195 bio
= bio_clone_bioset(*bio_orig
, GFP_NOIO
, fs_bio_set
);
197 bio_for_each_segment_all(to
, bio
, i
) {
198 struct page
*page
= to
->bv_page
;
200 if (page_to_pfn(page
) <= queue_bounce_pfn(q
))
203 to
->bv_page
= mempool_alloc(pool
, q
->bounce_gfp
);
204 inc_zone_page_state(to
->bv_page
, NR_BOUNCE
);
209 flush_dcache_page(page
);
211 vto
= page_address(to
->bv_page
) + to
->bv_offset
;
212 vfrom
= kmap_atomic(page
) + to
->bv_offset
;
213 memcpy(vto
, vfrom
, to
->bv_len
);
214 kunmap_atomic(vfrom
);
218 trace_block_bio_bounce(q
, *bio_orig
);
220 bio
->bi_flags
|= (1 << BIO_BOUNCED
);
222 if (pool
== page_pool
) {
223 bio
->bi_end_io
= bounce_end_io_write
;
225 bio
->bi_end_io
= bounce_end_io_read
;
227 bio
->bi_end_io
= bounce_end_io_write_isa
;
229 bio
->bi_end_io
= bounce_end_io_read_isa
;
232 bio
->bi_private
= *bio_orig
;
236 void blk_queue_bounce(struct request_queue
*q
, struct bio
**bio_orig
)
241 * Data-less bio, nothing to bounce
243 if (!bio_has_data(*bio_orig
))
247 * for non-isa bounce case, just check if the bounce pfn is equal
248 * to or bigger than the highest pfn in the system -- in that case,
249 * don't waste time iterating over bio segments
251 if (!(q
->bounce_gfp
& GFP_DMA
)) {
252 if (queue_bounce_pfn(q
) >= blk_max_pfn
)
256 BUG_ON(!isa_page_pool
);
257 pool
= isa_page_pool
;
263 __blk_queue_bounce(q
, bio_orig
, pool
);
266 EXPORT_SYMBOL(blk_queue_bounce
);
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