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/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>
17 #include <trace/block.h>
18 #include <asm/tlbflush.h>
21 #define ISA_POOL_SIZE 16
23 static mempool_t *page_pool, *isa_page_pool;
26 static __init int init_emergency_pool(void)
35 page_pool = mempool_create_page_pool(POOL_SIZE, 0);
37 printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
42 __initcall(init_emergency_pool);
45 * highmem version, map in to vec
47 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
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);
59 #else /* CONFIG_HIGHMEM */
61 #define bounce_copy_vec(to, vfrom) \
62 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
64 #endif /* CONFIG_HIGHMEM */
67 * allocate pages in the DMA region for the ISA pool
69 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
71 return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
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.
78 int init_emergency_isa_pool(void)
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);
87 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
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
96 static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
99 struct bio_vec *tovec, *fromvec;
102 __bio_for_each_segment(tovec, to, i, 0) {
103 fromvec = from->bi_io_vec + i;
108 if (tovec->bv_page == fromvec->bv_page)
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
116 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
118 flush_dcache_page(tovec->bv_page);
119 bounce_copy_vec(tovec, vfrom);
123 static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
125 struct bio *bio_orig = bio->bi_private;
126 struct bio_vec *bvec, *org_vec;
129 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
130 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
133 * free up bounce indirect pages used
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)
140 dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
141 mempool_free(bvec->bv_page, pool);
144 bio_endio(bio_orig, err);
148 static void bounce_end_io_write(struct bio *bio, int err)
150 bounce_end_io(bio, page_pool, err);
153 static void bounce_end_io_write_isa(struct bio *bio, int err)
156 bounce_end_io(bio, isa_page_pool, err);
159 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
161 struct bio *bio_orig = bio->bi_private;
163 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
164 copy_to_high_bio_irq(bio_orig, bio);
166 bounce_end_io(bio, pool, err);
169 static void bounce_end_io_read(struct bio *bio, int err)
171 __bounce_end_io_read(bio, page_pool, err);
174 static void bounce_end_io_read_isa(struct bio *bio, int err)
176 __bounce_end_io_read(bio, isa_page_pool, err);
179 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
183 struct bio *bio = NULL;
184 int i, rw = bio_data_dir(*bio_orig);
185 struct bio_vec *to, *from;
187 bio_for_each_segment(from, *bio_orig, i) {
188 page = from->bv_page;
191 * is destination page below bounce pfn?
193 if (page_to_pfn(page) <= q->bounce_pfn)
200 bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);
202 to = bio->bi_io_vec + i;
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);
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);
226 trace_block_bio_bounce(q, *bio_orig);
229 * at least one page was bounced, fill in possible non-highmem
232 __bio_for_each_segment(from, *bio_orig, i, 0) {
233 to = bio_iovec_idx(bio, i);
235 to->bv_page = from->bv_page;
236 to->bv_len = from->bv_len;
237 to->bv_offset = from->bv_offset;
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;
246 bio->bi_vcnt = (*bio_orig)->bi_vcnt;
247 bio->bi_idx = (*bio_orig)->bi_idx;
248 bio->bi_size = (*bio_orig)->bi_size;
250 if (pool == page_pool) {
251 bio->bi_end_io = bounce_end_io_write;
253 bio->bi_end_io = bounce_end_io_read;
255 bio->bi_end_io = bounce_end_io_write_isa;
257 bio->bi_end_io = bounce_end_io_read_isa;
260 bio->bi_private = *bio_orig;
264 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
269 * Data-less bio, nothing to bounce
271 if (!bio_has_data(*bio_orig))
275 * 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
279 if (!(q->bounce_gfp & GFP_DMA)) {
280 if (q->bounce_pfn >= blk_max_pfn)
284 BUG_ON(!isa_page_pool);
285 pool = isa_page_pool;
291 __blk_queue_bounce(q, bio_orig, pool);
294 EXPORT_SYMBOL(blk_queue_bounce);