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 #ifdef CONFIG_NEED_BOUNCE_POOL
181 static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)
183 if (bio_data_dir(bio) != WRITE)
186 if (!bdi_cap_stable_pages_required(&q->backing_dev_info))
189 return bio_flagged(bio, BIO_SNAP_STABLE);
192 static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)
196 #endif /* CONFIG_NEED_BOUNCE_POOL */
198 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
199 mempool_t *pool, int force)
202 int rw = bio_data_dir(*bio_orig);
203 struct bio_vec *to, from;
204 struct bvec_iter iter;
209 bio_for_each_segment(from, *bio_orig, iter)
210 if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q))
215 bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set);
217 bio_for_each_segment_all(to, bio, i) {
218 struct page *page = to->bv_page;
220 if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)
223 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
224 inc_zone_page_state(to->bv_page, NR_BOUNCE);
229 flush_dcache_page(page);
231 vto = page_address(to->bv_page) + to->bv_offset;
232 vfrom = kmap_atomic(page) + to->bv_offset;
233 memcpy(vto, vfrom, to->bv_len);
234 kunmap_atomic(vfrom);
238 trace_block_bio_bounce(q, *bio_orig);
240 bio->bi_flags |= (1 << BIO_BOUNCED);
242 if (pool == page_pool) {
243 bio->bi_end_io = bounce_end_io_write;
245 bio->bi_end_io = bounce_end_io_read;
247 bio->bi_end_io = bounce_end_io_write_isa;
249 bio->bi_end_io = bounce_end_io_read_isa;
252 bio->bi_private = *bio_orig;
256 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
262 * Data-less bio, nothing to bounce
264 if (!bio_has_data(*bio_orig))
267 must_bounce = must_snapshot_stable_pages(q, *bio_orig);
270 * for non-isa bounce case, just check if the bounce pfn is equal
271 * to or bigger than the highest pfn in the system -- in that case,
272 * don't waste time iterating over bio segments
274 if (!(q->bounce_gfp & GFP_DMA)) {
275 if (queue_bounce_pfn(q) >= blk_max_pfn && !must_bounce)
279 BUG_ON(!isa_page_pool);
280 pool = isa_page_pool;
286 __blk_queue_bounce(q, bio_orig, pool, must_bounce);
289 EXPORT_SYMBOL(blk_queue_bounce);