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/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> 23 24 #include <trace/events/block.h> 25 26 #define POOL_SIZE 64 27 #define ISA_POOL_SIZE 16 28 29 static mempool_t *page_pool, *isa_page_pool; 30 31 #if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL) 32 static __init int init_emergency_pool(void) 33 { 34 #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG) 35 if (max_pfn <= max_low_pfn) 36 return 0; 37 #endif 38 39 page_pool = mempool_create_page_pool(POOL_SIZE, 0); 40 BUG_ON(!page_pool); 41 pr_info("pool size: %d pages\n", POOL_SIZE); 42 43 return 0; 44 } 45 46 __initcall(init_emergency_pool); 47 #endif 48 49 #ifdef CONFIG_HIGHMEM 50 /* 51 * highmem version, map in to vec 52 */ 53 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) 54 { 55 unsigned long flags; 56 unsigned char *vto; 57 58 local_irq_save(flags); 59 vto = kmap_atomic(to->bv_page); 60 memcpy(vto + to->bv_offset, vfrom, to->bv_len); 61 kunmap_atomic(vto); 62 local_irq_restore(flags); 63 } 64 65 #else /* CONFIG_HIGHMEM */ 66 67 #define bounce_copy_vec(to, vfrom) \ 68 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) 69 70 #endif /* CONFIG_HIGHMEM */ 71 72 /* 73 * allocate pages in the DMA region for the ISA pool 74 */ 75 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data) 76 { 77 return mempool_alloc_pages(gfp_mask | GFP_DMA, data); 78 } 79 80 /* 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. 83 */ 84 int init_emergency_isa_pool(void) 85 { 86 if (isa_page_pool) 87 return 0; 88 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); 92 93 pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE); 94 return 0; 95 } 96 97 /* 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 101 */ 102 static void copy_to_high_bio_irq(struct bio *to, struct bio *from) 103 { 104 unsigned char *vfrom; 105 struct bio_vec tovec, *fromvec = from->bi_io_vec; 106 struct bvec_iter iter; 107 108 bio_for_each_segment(tovec, to, iter) { 109 if (tovec.bv_page != fromvec->bv_page) { 110 /* 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 114 */ 115 vfrom = page_address(fromvec->bv_page) + 116 tovec.bv_offset; 117 118 bounce_copy_vec(&tovec, vfrom); 119 flush_dcache_page(tovec.bv_page); 120 } 121 122 fromvec++; 123 } 124 } 125 126 static void bounce_end_io(struct bio *bio, mempool_t *pool) 127 { 128 struct bio *bio_orig = bio->bi_private; 129 struct bio_vec *bvec, *org_vec; 130 int i; 131 int start = bio_orig->bi_iter.bi_idx; 132 133 /* 134 * free up bounce indirect pages used 135 */ 136 bio_for_each_segment_all(bvec, bio, i) { 137 org_vec = bio_orig->bi_io_vec + i + start; 138 139 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_orig->bi_error = bio->bi_error; 147 bio_endio(bio_orig); 148 bio_put(bio); 149 } 150 151 static void bounce_end_io_write(struct bio *bio) 152 { 153 bounce_end_io(bio, page_pool); 154 } 155 156 static void bounce_end_io_write_isa(struct bio *bio) 157 { 158 159 bounce_end_io(bio, isa_page_pool); 160 } 161 162 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool) 163 { 164 struct bio *bio_orig = bio->bi_private; 165 166 if (!bio->bi_error) 167 copy_to_high_bio_irq(bio_orig, bio); 168 169 bounce_end_io(bio, pool); 170 } 171 172 static void bounce_end_io_read(struct bio *bio) 173 { 174 __bounce_end_io_read(bio, page_pool); 175 } 176 177 static void bounce_end_io_read_isa(struct bio *bio) 178 { 179 __bounce_end_io_read(bio, isa_page_pool); 180 } 181 182 #ifdef CONFIG_NEED_BOUNCE_POOL 183 static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) 184 { 185 if (bio_data_dir(bio) != WRITE) 186 return 0; 187 188 if (!bdi_cap_stable_pages_required(&q->backing_dev_info)) 189 return 0; 190 191 return bio_flagged(bio, BIO_SNAP_STABLE); 192 } 193 #else 194 static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) 195 { 196 return 0; 197 } 198 #endif /* CONFIG_NEED_BOUNCE_POOL */ 199 200 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, 201 mempool_t *pool, int force) 202 { 203 struct bio *bio; 204 int rw = bio_data_dir(*bio_orig); 205 struct bio_vec *to, from; 206 struct bvec_iter iter; 207 unsigned i; 208 209 if (force) 210 goto bounce; 211 bio_for_each_segment(from, *bio_orig, iter) 212 if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q)) 213 goto bounce; 214 215 return; 216 bounce: 217 bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set); 218 219 bio_for_each_segment_all(to, bio, i) { 220 struct page *page = to->bv_page; 221 222 if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force) 223 continue; 224 225 to->bv_page = mempool_alloc(pool, q->bounce_gfp); 226 inc_zone_page_state(to->bv_page, NR_BOUNCE); 227 228 if (rw == WRITE) { 229 char *vto, *vfrom; 230 231 flush_dcache_page(page); 232 233 vto = page_address(to->bv_page) + to->bv_offset; 234 vfrom = kmap_atomic(page) + to->bv_offset; 235 memcpy(vto, vfrom, to->bv_len); 236 kunmap_atomic(vfrom); 237 } 238 } 239 240 trace_block_bio_bounce(q, *bio_orig); 241 242 bio->bi_flags |= (1 << BIO_BOUNCED); 243 244 if (pool == page_pool) { 245 bio->bi_end_io = bounce_end_io_write; 246 if (rw == READ) 247 bio->bi_end_io = bounce_end_io_read; 248 } else { 249 bio->bi_end_io = bounce_end_io_write_isa; 250 if (rw == READ) 251 bio->bi_end_io = bounce_end_io_read_isa; 252 } 253 254 bio->bi_private = *bio_orig; 255 *bio_orig = bio; 256 } 257 258 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) 259 { 260 int must_bounce; 261 mempool_t *pool; 262 263 /* 264 * Data-less bio, nothing to bounce 265 */ 266 if (!bio_has_data(*bio_orig)) 267 return; 268 269 must_bounce = must_snapshot_stable_pages(q, *bio_orig); 270 271 /* 272 * for non-isa bounce case, just check if the bounce pfn is equal 273 * to or bigger than the highest pfn in the system -- in that case, 274 * don't waste time iterating over bio segments 275 */ 276 if (!(q->bounce_gfp & GFP_DMA)) { 277 if (queue_bounce_pfn(q) >= blk_max_pfn && !must_bounce) 278 return; 279 pool = page_pool; 280 } else { 281 BUG_ON(!isa_page_pool); 282 pool = isa_page_pool; 283 } 284 285 /* 286 * slow path 287 */ 288 __blk_queue_bounce(q, bio_orig, pool, must_bounce); 289 } 290 291 EXPORT_SYMBOL(blk_queue_bounce); 292