1 /* bounce buffer handling for block devices 2 * 3 * - Split from highmem.c 4 */ 5 6 #include <linux/mm.h> 7 #include <linux/export.h> 8 #include <linux/swap.h> 9 #include <linux/gfp.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 <linux/bootmem.h> 18 #include <asm/tlbflush.h> 19 20 #include <trace/events/block.h> 21 22 #define POOL_SIZE 64 23 #define ISA_POOL_SIZE 16 24 25 static mempool_t *page_pool, *isa_page_pool; 26 27 #if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL) 28 static __init int init_emergency_pool(void) 29 { 30 #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG) 31 if (max_pfn <= max_low_pfn) 32 return 0; 33 #endif 34 35 page_pool = mempool_create_page_pool(POOL_SIZE, 0); 36 BUG_ON(!page_pool); 37 printk("bounce pool size: %d pages\n", POOL_SIZE); 38 39 return 0; 40 } 41 42 __initcall(init_emergency_pool); 43 #endif 44 45 #ifdef CONFIG_HIGHMEM 46 /* 47 * highmem version, map in to vec 48 */ 49 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) 50 { 51 unsigned long flags; 52 unsigned char *vto; 53 54 local_irq_save(flags); 55 vto = kmap_atomic(to->bv_page); 56 memcpy(vto + to->bv_offset, vfrom, to->bv_len); 57 kunmap_atomic(vto); 58 local_irq_restore(flags); 59 } 60 61 #else /* CONFIG_HIGHMEM */ 62 63 #define bounce_copy_vec(to, vfrom) \ 64 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) 65 66 #endif /* CONFIG_HIGHMEM */ 67 68 /* 69 * allocate pages in the DMA region for the ISA pool 70 */ 71 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data) 72 { 73 return mempool_alloc_pages(gfp_mask | GFP_DMA, data); 74 } 75 76 /* 77 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA 78 * as the max address, so check if the pool has already been created. 79 */ 80 int init_emergency_isa_pool(void) 81 { 82 if (isa_page_pool) 83 return 0; 84 85 isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa, 86 mempool_free_pages, (void *) 0); 87 BUG_ON(!isa_page_pool); 88 89 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE); 90 return 0; 91 } 92 93 /* 94 * Simple bounce buffer support for highmem pages. Depending on the 95 * queue gfp mask set, *to may or may not be a highmem page. kmap it 96 * always, it will do the Right Thing 97 */ 98 static void copy_to_high_bio_irq(struct bio *to, struct bio *from) 99 { 100 unsigned char *vfrom; 101 struct bio_vec tovec, *fromvec = from->bi_io_vec; 102 struct bvec_iter iter; 103 104 bio_for_each_segment(tovec, to, iter) { 105 if (tovec.bv_page != fromvec->bv_page) { 106 /* 107 * fromvec->bv_offset and fromvec->bv_len might have 108 * been modified by the block layer, so use the original 109 * copy, bounce_copy_vec already uses tovec->bv_len 110 */ 111 vfrom = page_address(fromvec->bv_page) + 112 tovec.bv_offset; 113 114 bounce_copy_vec(&tovec, vfrom); 115 flush_dcache_page(tovec.bv_page); 116 } 117 118 fromvec++; 119 } 120 } 121 122 static void bounce_end_io(struct bio *bio, mempool_t *pool, int err) 123 { 124 struct bio *bio_orig = bio->bi_private; 125 struct bio_vec *bvec, *org_vec; 126 int i; 127 128 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags)) 129 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags); 130 131 /* 132 * free up bounce indirect pages used 133 */ 134 bio_for_each_segment_all(bvec, bio, i) { 135 org_vec = bio_orig->bi_io_vec + i; 136 if (bvec->bv_page == org_vec->bv_page) 137 continue; 138 139 dec_zone_page_state(bvec->bv_page, NR_BOUNCE); 140 mempool_free(bvec->bv_page, pool); 141 } 142 143 bio_endio(bio_orig, err); 144 bio_put(bio); 145 } 146 147 static void bounce_end_io_write(struct bio *bio, int err) 148 { 149 bounce_end_io(bio, page_pool, err); 150 } 151 152 static void bounce_end_io_write_isa(struct bio *bio, int err) 153 { 154 155 bounce_end_io(bio, isa_page_pool, err); 156 } 157 158 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err) 159 { 160 struct bio *bio_orig = bio->bi_private; 161 162 if (test_bit(BIO_UPTODATE, &bio->bi_flags)) 163 copy_to_high_bio_irq(bio_orig, bio); 164 165 bounce_end_io(bio, pool, err); 166 } 167 168 static void bounce_end_io_read(struct bio *bio, int err) 169 { 170 __bounce_end_io_read(bio, page_pool, err); 171 } 172 173 static void bounce_end_io_read_isa(struct bio *bio, int err) 174 { 175 __bounce_end_io_read(bio, isa_page_pool, err); 176 } 177 178 #ifdef CONFIG_NEED_BOUNCE_POOL 179 static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) 180 { 181 if (bio_data_dir(bio) != WRITE) 182 return 0; 183 184 if (!bdi_cap_stable_pages_required(&q->backing_dev_info)) 185 return 0; 186 187 return test_bit(BIO_SNAP_STABLE, &bio->bi_flags); 188 } 189 #else 190 static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) 191 { 192 return 0; 193 } 194 #endif /* CONFIG_NEED_BOUNCE_POOL */ 195 196 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, 197 mempool_t *pool, int force) 198 { 199 struct bio *bio; 200 int rw = bio_data_dir(*bio_orig); 201 struct bio_vec *to, from; 202 struct bvec_iter iter; 203 unsigned i; 204 205 if (force) 206 goto bounce; 207 bio_for_each_segment(from, *bio_orig, iter) 208 if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q)) 209 goto bounce; 210 211 return; 212 bounce: 213 bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set); 214 215 bio_for_each_segment_all(to, bio, i) { 216 struct page *page = to->bv_page; 217 218 if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force) 219 continue; 220 221 inc_zone_page_state(to->bv_page, NR_BOUNCE); 222 to->bv_page = mempool_alloc(pool, q->bounce_gfp); 223 224 if (rw == WRITE) { 225 char *vto, *vfrom; 226 227 flush_dcache_page(page); 228 229 vto = page_address(to->bv_page) + to->bv_offset; 230 vfrom = kmap_atomic(page) + to->bv_offset; 231 memcpy(vto, vfrom, to->bv_len); 232 kunmap_atomic(vfrom); 233 } 234 } 235 236 trace_block_bio_bounce(q, *bio_orig); 237 238 bio->bi_flags |= (1 << BIO_BOUNCED); 239 240 if (pool == page_pool) { 241 bio->bi_end_io = bounce_end_io_write; 242 if (rw == READ) 243 bio->bi_end_io = bounce_end_io_read; 244 } else { 245 bio->bi_end_io = bounce_end_io_write_isa; 246 if (rw == READ) 247 bio->bi_end_io = bounce_end_io_read_isa; 248 } 249 250 bio->bi_private = *bio_orig; 251 *bio_orig = bio; 252 } 253 254 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) 255 { 256 int must_bounce; 257 mempool_t *pool; 258 259 /* 260 * Data-less bio, nothing to bounce 261 */ 262 if (!bio_has_data(*bio_orig)) 263 return; 264 265 must_bounce = must_snapshot_stable_pages(q, *bio_orig); 266 267 /* 268 * for non-isa bounce case, just check if the bounce pfn is equal 269 * to or bigger than the highest pfn in the system -- in that case, 270 * don't waste time iterating over bio segments 271 */ 272 if (!(q->bounce_gfp & GFP_DMA)) { 273 if (queue_bounce_pfn(q) >= blk_max_pfn && !must_bounce) 274 return; 275 pool = page_pool; 276 } else { 277 BUG_ON(!isa_page_pool); 278 pool = isa_page_pool; 279 } 280 281 /* 282 * slow path 283 */ 284 __blk_queue_bounce(q, bio_orig, pool, must_bounce); 285 } 286 287 EXPORT_SYMBOL(blk_queue_bounce); 288