1 /* bounce buffer handling for block devices 2 * 3 * - Split from highmem.c 4 */ 5 6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 7 8 #include <linux/mm.h> 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/init.h> 17 #include <linux/hash.h> 18 #include <linux/highmem.h> 19 #include <linux/bootmem.h> 20 #include <linux/printk.h> 21 #include <asm/tlbflush.h> 22 23 #include <trace/events/block.h> 24 25 #define POOL_SIZE 64 26 #define ISA_POOL_SIZE 16 27 28 static mempool_t *page_pool, *isa_page_pool; 29 30 #if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL) 31 static __init int init_emergency_pool(void) 32 { 33 #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG) 34 if (max_pfn <= max_low_pfn) 35 return 0; 36 #endif 37 38 page_pool = mempool_create_page_pool(POOL_SIZE, 0); 39 BUG_ON(!page_pool); 40 pr_info("pool size: %d pages\n", POOL_SIZE); 41 42 return 0; 43 } 44 45 __initcall(init_emergency_pool); 46 #endif 47 48 #ifdef CONFIG_HIGHMEM 49 /* 50 * highmem version, map in to vec 51 */ 52 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) 53 { 54 unsigned long flags; 55 unsigned char *vto; 56 57 local_irq_save(flags); 58 vto = kmap_atomic(to->bv_page); 59 memcpy(vto + to->bv_offset, vfrom, to->bv_len); 60 kunmap_atomic(vto); 61 local_irq_restore(flags); 62 } 63 64 #else /* CONFIG_HIGHMEM */ 65 66 #define bounce_copy_vec(to, vfrom) \ 67 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) 68 69 #endif /* CONFIG_HIGHMEM */ 70 71 /* 72 * allocate pages in the DMA region for the ISA pool 73 */ 74 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data) 75 { 76 return mempool_alloc_pages(gfp_mask | GFP_DMA, data); 77 } 78 79 /* 80 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA 81 * as the max address, so check if the pool has already been created. 82 */ 83 int init_emergency_isa_pool(void) 84 { 85 if (isa_page_pool) 86 return 0; 87 88 isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa, 89 mempool_free_pages, (void *) 0); 90 BUG_ON(!isa_page_pool); 91 92 pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE); 93 return 0; 94 } 95 96 /* 97 * Simple bounce buffer support for highmem pages. Depending on the 98 * queue gfp mask set, *to may or may not be a highmem page. kmap it 99 * always, it will do the Right Thing 100 */ 101 static void copy_to_high_bio_irq(struct bio *to, struct bio *from) 102 { 103 unsigned char *vfrom; 104 struct bio_vec tovec, *fromvec = from->bi_io_vec; 105 struct bvec_iter iter; 106 107 bio_for_each_segment(tovec, to, iter) { 108 if (tovec.bv_page != fromvec->bv_page) { 109 /* 110 * fromvec->bv_offset and fromvec->bv_len might have 111 * been modified by the block layer, so use the original 112 * copy, bounce_copy_vec already uses tovec->bv_len 113 */ 114 vfrom = page_address(fromvec->bv_page) + 115 tovec.bv_offset; 116 117 bounce_copy_vec(&tovec, vfrom); 118 flush_dcache_page(tovec.bv_page); 119 } 120 121 fromvec++; 122 } 123 } 124 125 static void bounce_end_io(struct bio *bio, mempool_t *pool, int err) 126 { 127 struct bio *bio_orig = bio->bi_private; 128 struct bio_vec *bvec, *org_vec; 129 int i; 130 131 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags)) 132 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags); 133 134 /* 135 * free up bounce indirect pages used 136 */ 137 bio_for_each_segment_all(bvec, bio, i) { 138 org_vec = bio_orig->bi_io_vec + i; 139 if (bvec->bv_page == org_vec->bv_page) 140 continue; 141 142 dec_zone_page_state(bvec->bv_page, NR_BOUNCE); 143 mempool_free(bvec->bv_page, pool); 144 } 145 146 bio_endio(bio_orig, err); 147 bio_put(bio); 148 } 149 150 static void bounce_end_io_write(struct bio *bio, int err) 151 { 152 bounce_end_io(bio, page_pool, err); 153 } 154 155 static void bounce_end_io_write_isa(struct bio *bio, int err) 156 { 157 158 bounce_end_io(bio, isa_page_pool, err); 159 } 160 161 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err) 162 { 163 struct bio *bio_orig = bio->bi_private; 164 165 if (test_bit(BIO_UPTODATE, &bio->bi_flags)) 166 copy_to_high_bio_irq(bio_orig, bio); 167 168 bounce_end_io(bio, pool, err); 169 } 170 171 static void bounce_end_io_read(struct bio *bio, int err) 172 { 173 __bounce_end_io_read(bio, page_pool, err); 174 } 175 176 static void bounce_end_io_read_isa(struct bio *bio, int err) 177 { 178 __bounce_end_io_read(bio, isa_page_pool, err); 179 } 180 181 #ifdef CONFIG_NEED_BOUNCE_POOL 182 static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) 183 { 184 if (bio_data_dir(bio) != WRITE) 185 return 0; 186 187 if (!bdi_cap_stable_pages_required(&q->backing_dev_info)) 188 return 0; 189 190 return test_bit(BIO_SNAP_STABLE, &bio->bi_flags); 191 } 192 #else 193 static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) 194 { 195 return 0; 196 } 197 #endif /* CONFIG_NEED_BOUNCE_POOL */ 198 199 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, 200 mempool_t *pool, int force) 201 { 202 struct bio *bio; 203 int rw = bio_data_dir(*bio_orig); 204 struct bio_vec *to, from; 205 struct bvec_iter iter; 206 unsigned i; 207 208 if (force) 209 goto bounce; 210 bio_for_each_segment(from, *bio_orig, iter) 211 if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q)) 212 goto bounce; 213 214 return; 215 bounce: 216 bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set); 217 218 bio_for_each_segment_all(to, bio, i) { 219 struct page *page = to->bv_page; 220 221 if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force) 222 continue; 223 224 to->bv_page = mempool_alloc(pool, q->bounce_gfp); 225 inc_zone_page_state(to->bv_page, NR_BOUNCE); 226 227 if (rw == WRITE) { 228 char *vto, *vfrom; 229 230 flush_dcache_page(page); 231 232 vto = page_address(to->bv_page) + to->bv_offset; 233 vfrom = kmap_atomic(page) + to->bv_offset; 234 memcpy(vto, vfrom, to->bv_len); 235 kunmap_atomic(vfrom); 236 } 237 } 238 239 trace_block_bio_bounce(q, *bio_orig); 240 241 bio->bi_flags |= (1 << BIO_BOUNCED); 242 243 if (pool == page_pool) { 244 bio->bi_end_io = bounce_end_io_write; 245 if (rw == READ) 246 bio->bi_end_io = bounce_end_io_read; 247 } else { 248 bio->bi_end_io = bounce_end_io_write_isa; 249 if (rw == READ) 250 bio->bi_end_io = bounce_end_io_read_isa; 251 } 252 253 bio->bi_private = *bio_orig; 254 *bio_orig = bio; 255 } 256 257 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) 258 { 259 int must_bounce; 260 mempool_t *pool; 261 262 /* 263 * Data-less bio, nothing to bounce 264 */ 265 if (!bio_has_data(*bio_orig)) 266 return; 267 268 must_bounce = must_snapshot_stable_pages(q, *bio_orig); 269 270 /* 271 * for non-isa bounce case, just check if the bounce pfn is equal 272 * to or bigger than the highest pfn in the system -- in that case, 273 * don't waste time iterating over bio segments 274 */ 275 if (!(q->bounce_gfp & GFP_DMA)) { 276 if (queue_bounce_pfn(q) >= blk_max_pfn && !must_bounce) 277 return; 278 pool = page_pool; 279 } else { 280 BUG_ON(!isa_page_pool); 281 pool = isa_page_pool; 282 } 283 284 /* 285 * slow path 286 */ 287 __blk_queue_bounce(q, bio_orig, pool, must_bounce); 288 } 289 290 EXPORT_SYMBOL(blk_queue_bounce); 291