1 // SPDX-License-Identifier: GPL-2.0 2 /* bounce buffer handling for block devices 3 * 4 * - Split from highmem.c 5 */ 6 7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 8 9 #include <linux/mm.h> 10 #include <linux/export.h> 11 #include <linux/swap.h> 12 #include <linux/gfp.h> 13 #include <linux/bio.h> 14 #include <linux/pagemap.h> 15 #include <linux/mempool.h> 16 #include <linux/blkdev.h> 17 #include <linux/backing-dev.h> 18 #include <linux/init.h> 19 #include <linux/hash.h> 20 #include <linux/highmem.h> 21 #include <linux/bootmem.h> 22 #include <linux/printk.h> 23 #include <asm/tlbflush.h> 24 25 #include <trace/events/block.h> 26 #include "blk.h" 27 28 #define POOL_SIZE 64 29 #define ISA_POOL_SIZE 16 30 31 static struct bio_set bounce_bio_set, bounce_bio_split; 32 static mempool_t page_pool, isa_page_pool; 33 34 #if defined(CONFIG_HIGHMEM) 35 static __init int init_emergency_pool(void) 36 { 37 int ret; 38 #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG) 39 if (max_pfn <= max_low_pfn) 40 return 0; 41 #endif 42 43 ret = mempool_init_page_pool(&page_pool, POOL_SIZE, 0); 44 BUG_ON(ret); 45 pr_info("pool size: %d pages\n", POOL_SIZE); 46 47 ret = bioset_init(&bounce_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); 48 BUG_ON(ret); 49 if (bioset_integrity_create(&bounce_bio_set, BIO_POOL_SIZE)) 50 BUG_ON(1); 51 52 ret = bioset_init(&bounce_bio_split, BIO_POOL_SIZE, 0, 0); 53 BUG_ON(ret); 54 55 return 0; 56 } 57 58 __initcall(init_emergency_pool); 59 #endif 60 61 #ifdef CONFIG_HIGHMEM 62 /* 63 * highmem version, map in to vec 64 */ 65 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) 66 { 67 unsigned char *vto; 68 69 vto = kmap_atomic(to->bv_page); 70 memcpy(vto + to->bv_offset, vfrom, to->bv_len); 71 kunmap_atomic(vto); 72 } 73 74 #else /* CONFIG_HIGHMEM */ 75 76 #define bounce_copy_vec(to, vfrom) \ 77 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) 78 79 #endif /* CONFIG_HIGHMEM */ 80 81 /* 82 * allocate pages in the DMA region for the ISA pool 83 */ 84 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data) 85 { 86 return mempool_alloc_pages(gfp_mask | GFP_DMA, data); 87 } 88 89 /* 90 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA 91 * as the max address, so check if the pool has already been created. 92 */ 93 int init_emergency_isa_pool(void) 94 { 95 int ret; 96 97 if (mempool_initialized(&isa_page_pool)) 98 return 0; 99 100 ret = mempool_init(&isa_page_pool, ISA_POOL_SIZE, mempool_alloc_pages_isa, 101 mempool_free_pages, (void *) 0); 102 BUG_ON(ret); 103 104 pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE); 105 return 0; 106 } 107 108 /* 109 * Simple bounce buffer support for highmem pages. Depending on the 110 * queue gfp mask set, *to may or may not be a highmem page. kmap it 111 * always, it will do the Right Thing 112 */ 113 static void copy_to_high_bio_irq(struct bio *to, struct bio *from) 114 { 115 unsigned char *vfrom; 116 struct bio_vec tovec, fromvec; 117 struct bvec_iter iter; 118 /* 119 * The bio of @from is created by bounce, so we can iterate 120 * its bvec from start to end, but the @from->bi_iter can't be 121 * trusted because it might be changed by splitting. 122 */ 123 struct bvec_iter from_iter = BVEC_ITER_ALL_INIT; 124 125 bio_for_each_segment(tovec, to, iter) { 126 fromvec = bio_iter_iovec(from, from_iter); 127 if (tovec.bv_page != fromvec.bv_page) { 128 /* 129 * fromvec->bv_offset and fromvec->bv_len might have 130 * been modified by the block layer, so use the original 131 * copy, bounce_copy_vec already uses tovec->bv_len 132 */ 133 vfrom = page_address(fromvec.bv_page) + 134 tovec.bv_offset; 135 136 bounce_copy_vec(&tovec, vfrom); 137 flush_dcache_page(tovec.bv_page); 138 } 139 bio_advance_iter(from, &from_iter, tovec.bv_len); 140 } 141 } 142 143 static void bounce_end_io(struct bio *bio, mempool_t *pool) 144 { 145 struct bio *bio_orig = bio->bi_private; 146 struct bio_vec *bvec, orig_vec; 147 int i; 148 struct bvec_iter orig_iter = bio_orig->bi_iter; 149 150 /* 151 * free up bounce indirect pages used 152 */ 153 bio_for_each_segment_all(bvec, bio, i) { 154 orig_vec = bio_iter_iovec(bio_orig, orig_iter); 155 if (bvec->bv_page != orig_vec.bv_page) { 156 dec_zone_page_state(bvec->bv_page, NR_BOUNCE); 157 mempool_free(bvec->bv_page, pool); 158 } 159 bio_advance_iter(bio_orig, &orig_iter, orig_vec.bv_len); 160 } 161 162 bio_orig->bi_status = bio->bi_status; 163 bio_endio(bio_orig); 164 bio_put(bio); 165 } 166 167 static void bounce_end_io_write(struct bio *bio) 168 { 169 bounce_end_io(bio, &page_pool); 170 } 171 172 static void bounce_end_io_write_isa(struct bio *bio) 173 { 174 175 bounce_end_io(bio, &isa_page_pool); 176 } 177 178 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool) 179 { 180 struct bio *bio_orig = bio->bi_private; 181 182 if (!bio->bi_status) 183 copy_to_high_bio_irq(bio_orig, bio); 184 185 bounce_end_io(bio, pool); 186 } 187 188 static void bounce_end_io_read(struct bio *bio) 189 { 190 __bounce_end_io_read(bio, &page_pool); 191 } 192 193 static void bounce_end_io_read_isa(struct bio *bio) 194 { 195 __bounce_end_io_read(bio, &isa_page_pool); 196 } 197 198 static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask, 199 struct bio_set *bs) 200 { 201 struct bvec_iter iter; 202 struct bio_vec bv; 203 struct bio *bio; 204 205 /* 206 * Pre immutable biovecs, __bio_clone() used to just do a memcpy from 207 * bio_src->bi_io_vec to bio->bi_io_vec. 208 * 209 * We can't do that anymore, because: 210 * 211 * - The point of cloning the biovec is to produce a bio with a biovec 212 * the caller can modify: bi_idx and bi_bvec_done should be 0. 213 * 214 * - The original bio could've had more than BIO_MAX_PAGES biovecs; if 215 * we tried to clone the whole thing bio_alloc_bioset() would fail. 216 * But the clone should succeed as long as the number of biovecs we 217 * actually need to allocate is fewer than BIO_MAX_PAGES. 218 * 219 * - Lastly, bi_vcnt should not be looked at or relied upon by code 220 * that does not own the bio - reason being drivers don't use it for 221 * iterating over the biovec anymore, so expecting it to be kept up 222 * to date (i.e. for clones that share the parent biovec) is just 223 * asking for trouble and would force extra work on 224 * __bio_clone_fast() anyways. 225 */ 226 227 bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs); 228 if (!bio) 229 return NULL; 230 bio->bi_disk = bio_src->bi_disk; 231 bio->bi_opf = bio_src->bi_opf; 232 bio->bi_write_hint = bio_src->bi_write_hint; 233 bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector; 234 bio->bi_iter.bi_size = bio_src->bi_iter.bi_size; 235 236 switch (bio_op(bio)) { 237 case REQ_OP_DISCARD: 238 case REQ_OP_SECURE_ERASE: 239 case REQ_OP_WRITE_ZEROES: 240 break; 241 case REQ_OP_WRITE_SAME: 242 bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0]; 243 break; 244 default: 245 bio_for_each_segment(bv, bio_src, iter) 246 bio->bi_io_vec[bio->bi_vcnt++] = bv; 247 break; 248 } 249 250 if (bio_integrity(bio_src)) { 251 int ret; 252 253 ret = bio_integrity_clone(bio, bio_src, gfp_mask); 254 if (ret < 0) { 255 bio_put(bio); 256 return NULL; 257 } 258 } 259 260 bio_clone_blkcg_association(bio, bio_src); 261 262 return bio; 263 } 264 265 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, 266 mempool_t *pool) 267 { 268 struct bio *bio; 269 int rw = bio_data_dir(*bio_orig); 270 struct bio_vec *to, from; 271 struct bvec_iter iter; 272 unsigned i = 0; 273 bool bounce = false; 274 int sectors = 0; 275 bool passthrough = bio_is_passthrough(*bio_orig); 276 277 bio_for_each_segment(from, *bio_orig, iter) { 278 if (i++ < BIO_MAX_PAGES) 279 sectors += from.bv_len >> 9; 280 if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn) 281 bounce = true; 282 } 283 if (!bounce) 284 return; 285 286 if (!passthrough && sectors < bio_sectors(*bio_orig)) { 287 bio = bio_split(*bio_orig, sectors, GFP_NOIO, &bounce_bio_split); 288 bio_chain(bio, *bio_orig); 289 generic_make_request(*bio_orig); 290 *bio_orig = bio; 291 } 292 bio = bounce_clone_bio(*bio_orig, GFP_NOIO, passthrough ? NULL : 293 &bounce_bio_set); 294 295 bio_for_each_segment_all(to, bio, i) { 296 struct page *page = to->bv_page; 297 298 if (page_to_pfn(page) <= q->limits.bounce_pfn) 299 continue; 300 301 to->bv_page = mempool_alloc(pool, q->bounce_gfp); 302 inc_zone_page_state(to->bv_page, NR_BOUNCE); 303 304 if (rw == WRITE) { 305 char *vto, *vfrom; 306 307 flush_dcache_page(page); 308 309 vto = page_address(to->bv_page) + to->bv_offset; 310 vfrom = kmap_atomic(page) + to->bv_offset; 311 memcpy(vto, vfrom, to->bv_len); 312 kunmap_atomic(vfrom); 313 } 314 } 315 316 trace_block_bio_bounce(q, *bio_orig); 317 318 bio->bi_flags |= (1 << BIO_BOUNCED); 319 320 if (pool == &page_pool) { 321 bio->bi_end_io = bounce_end_io_write; 322 if (rw == READ) 323 bio->bi_end_io = bounce_end_io_read; 324 } else { 325 bio->bi_end_io = bounce_end_io_write_isa; 326 if (rw == READ) 327 bio->bi_end_io = bounce_end_io_read_isa; 328 } 329 330 bio->bi_private = *bio_orig; 331 *bio_orig = bio; 332 } 333 334 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) 335 { 336 mempool_t *pool; 337 338 /* 339 * Data-less bio, nothing to bounce 340 */ 341 if (!bio_has_data(*bio_orig)) 342 return; 343 344 /* 345 * for non-isa bounce case, just check if the bounce pfn is equal 346 * to or bigger than the highest pfn in the system -- in that case, 347 * don't waste time iterating over bio segments 348 */ 349 if (!(q->bounce_gfp & GFP_DMA)) { 350 if (q->limits.bounce_pfn >= blk_max_pfn) 351 return; 352 pool = &page_pool; 353 } else { 354 BUG_ON(!mempool_initialized(&isa_page_pool)); 355 pool = &isa_page_pool; 356 } 357 358 /* 359 * slow path 360 */ 361 __blk_queue_bounce(q, bio_orig, pool); 362 } 363