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/memblock.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 static void init_bounce_bioset(void) 35 { 36 static bool bounce_bs_setup; 37 int ret; 38 39 if (bounce_bs_setup) 40 return; 41 42 ret = bioset_init(&bounce_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); 43 BUG_ON(ret); 44 if (bioset_integrity_create(&bounce_bio_set, BIO_POOL_SIZE)) 45 BUG_ON(1); 46 47 ret = bioset_init(&bounce_bio_split, BIO_POOL_SIZE, 0, 0); 48 BUG_ON(ret); 49 bounce_bs_setup = true; 50 } 51 52 #if defined(CONFIG_HIGHMEM) 53 static __init int init_emergency_pool(void) 54 { 55 int ret; 56 #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG) 57 if (max_pfn <= max_low_pfn) 58 return 0; 59 #endif 60 61 ret = mempool_init_page_pool(&page_pool, POOL_SIZE, 0); 62 BUG_ON(ret); 63 pr_info("pool size: %d pages\n", POOL_SIZE); 64 65 init_bounce_bioset(); 66 return 0; 67 } 68 69 __initcall(init_emergency_pool); 70 #endif 71 72 #ifdef CONFIG_HIGHMEM 73 /* 74 * highmem version, map in to vec 75 */ 76 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) 77 { 78 unsigned char *vto; 79 80 vto = kmap_atomic(to->bv_page); 81 memcpy(vto + to->bv_offset, vfrom, to->bv_len); 82 kunmap_atomic(vto); 83 } 84 85 #else /* CONFIG_HIGHMEM */ 86 87 #define bounce_copy_vec(to, vfrom) \ 88 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) 89 90 #endif /* CONFIG_HIGHMEM */ 91 92 /* 93 * allocate pages in the DMA region for the ISA pool 94 */ 95 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data) 96 { 97 return mempool_alloc_pages(gfp_mask | GFP_DMA, data); 98 } 99 100 static DEFINE_MUTEX(isa_mutex); 101 102 /* 103 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA 104 * as the max address, so check if the pool has already been created. 105 */ 106 int init_emergency_isa_pool(void) 107 { 108 int ret; 109 110 mutex_lock(&isa_mutex); 111 112 if (mempool_initialized(&isa_page_pool)) { 113 mutex_unlock(&isa_mutex); 114 return 0; 115 } 116 117 ret = mempool_init(&isa_page_pool, ISA_POOL_SIZE, mempool_alloc_pages_isa, 118 mempool_free_pages, (void *) 0); 119 BUG_ON(ret); 120 121 pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE); 122 init_bounce_bioset(); 123 mutex_unlock(&isa_mutex); 124 return 0; 125 } 126 127 /* 128 * Simple bounce buffer support for highmem pages. Depending on the 129 * queue gfp mask set, *to may or may not be a highmem page. kmap it 130 * always, it will do the Right Thing 131 */ 132 static void copy_to_high_bio_irq(struct bio *to, struct bio *from) 133 { 134 unsigned char *vfrom; 135 struct bio_vec tovec, fromvec; 136 struct bvec_iter iter; 137 /* 138 * The bio of @from is created by bounce, so we can iterate 139 * its bvec from start to end, but the @from->bi_iter can't be 140 * trusted because it might be changed by splitting. 141 */ 142 struct bvec_iter from_iter = BVEC_ITER_ALL_INIT; 143 144 bio_for_each_segment(tovec, to, iter) { 145 fromvec = bio_iter_iovec(from, from_iter); 146 if (tovec.bv_page != fromvec.bv_page) { 147 /* 148 * fromvec->bv_offset and fromvec->bv_len might have 149 * been modified by the block layer, so use the original 150 * copy, bounce_copy_vec already uses tovec->bv_len 151 */ 152 vfrom = page_address(fromvec.bv_page) + 153 tovec.bv_offset; 154 155 bounce_copy_vec(&tovec, vfrom); 156 flush_dcache_page(tovec.bv_page); 157 } 158 bio_advance_iter(from, &from_iter, tovec.bv_len); 159 } 160 } 161 162 static void bounce_end_io(struct bio *bio, mempool_t *pool) 163 { 164 struct bio *bio_orig = bio->bi_private; 165 struct bio_vec *bvec, orig_vec; 166 struct bvec_iter orig_iter = bio_orig->bi_iter; 167 struct bvec_iter_all iter_all; 168 169 /* 170 * free up bounce indirect pages used 171 */ 172 bio_for_each_segment_all(bvec, bio, iter_all) { 173 orig_vec = bio_iter_iovec(bio_orig, orig_iter); 174 if (bvec->bv_page != orig_vec.bv_page) { 175 dec_zone_page_state(bvec->bv_page, NR_BOUNCE); 176 mempool_free(bvec->bv_page, pool); 177 } 178 bio_advance_iter(bio_orig, &orig_iter, orig_vec.bv_len); 179 } 180 181 bio_orig->bi_status = bio->bi_status; 182 bio_endio(bio_orig); 183 bio_put(bio); 184 } 185 186 static void bounce_end_io_write(struct bio *bio) 187 { 188 bounce_end_io(bio, &page_pool); 189 } 190 191 static void bounce_end_io_write_isa(struct bio *bio) 192 { 193 194 bounce_end_io(bio, &isa_page_pool); 195 } 196 197 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool) 198 { 199 struct bio *bio_orig = bio->bi_private; 200 201 if (!bio->bi_status) 202 copy_to_high_bio_irq(bio_orig, bio); 203 204 bounce_end_io(bio, pool); 205 } 206 207 static void bounce_end_io_read(struct bio *bio) 208 { 209 __bounce_end_io_read(bio, &page_pool); 210 } 211 212 static void bounce_end_io_read_isa(struct bio *bio) 213 { 214 __bounce_end_io_read(bio, &isa_page_pool); 215 } 216 217 static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask, 218 struct bio_set *bs) 219 { 220 struct bvec_iter iter; 221 struct bio_vec bv; 222 struct bio *bio; 223 224 /* 225 * Pre immutable biovecs, __bio_clone() used to just do a memcpy from 226 * bio_src->bi_io_vec to bio->bi_io_vec. 227 * 228 * We can't do that anymore, because: 229 * 230 * - The point of cloning the biovec is to produce a bio with a biovec 231 * the caller can modify: bi_idx and bi_bvec_done should be 0. 232 * 233 * - The original bio could've had more than BIO_MAX_PAGES biovecs; if 234 * we tried to clone the whole thing bio_alloc_bioset() would fail. 235 * But the clone should succeed as long as the number of biovecs we 236 * actually need to allocate is fewer than BIO_MAX_PAGES. 237 * 238 * - Lastly, bi_vcnt should not be looked at or relied upon by code 239 * that does not own the bio - reason being drivers don't use it for 240 * iterating over the biovec anymore, so expecting it to be kept up 241 * to date (i.e. for clones that share the parent biovec) is just 242 * asking for trouble and would force extra work on 243 * __bio_clone_fast() anyways. 244 */ 245 246 bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs); 247 if (!bio) 248 return NULL; 249 bio->bi_disk = bio_src->bi_disk; 250 bio->bi_opf = bio_src->bi_opf; 251 bio->bi_ioprio = bio_src->bi_ioprio; 252 bio->bi_write_hint = bio_src->bi_write_hint; 253 bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector; 254 bio->bi_iter.bi_size = bio_src->bi_iter.bi_size; 255 256 switch (bio_op(bio)) { 257 case REQ_OP_DISCARD: 258 case REQ_OP_SECURE_ERASE: 259 case REQ_OP_WRITE_ZEROES: 260 break; 261 case REQ_OP_WRITE_SAME: 262 bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0]; 263 break; 264 default: 265 bio_for_each_segment(bv, bio_src, iter) 266 bio->bi_io_vec[bio->bi_vcnt++] = bv; 267 break; 268 } 269 270 if (bio_crypt_clone(bio, bio_src, gfp_mask) < 0) 271 goto err_put; 272 273 if (bio_integrity(bio_src) && 274 bio_integrity_clone(bio, bio_src, gfp_mask) < 0) 275 goto err_put; 276 277 bio_clone_blkg_association(bio, bio_src); 278 blkcg_bio_issue_init(bio); 279 280 return bio; 281 282 err_put: 283 bio_put(bio); 284 return NULL; 285 } 286 287 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, 288 mempool_t *pool) 289 { 290 struct bio *bio; 291 int rw = bio_data_dir(*bio_orig); 292 struct bio_vec *to, from; 293 struct bvec_iter iter; 294 unsigned i = 0; 295 bool bounce = false; 296 int sectors = 0; 297 bool passthrough = bio_is_passthrough(*bio_orig); 298 299 bio_for_each_segment(from, *bio_orig, iter) { 300 if (i++ < BIO_MAX_PAGES) 301 sectors += from.bv_len >> 9; 302 if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn) 303 bounce = true; 304 } 305 if (!bounce) 306 return; 307 308 if (!passthrough && sectors < bio_sectors(*bio_orig)) { 309 bio = bio_split(*bio_orig, sectors, GFP_NOIO, &bounce_bio_split); 310 bio_chain(bio, *bio_orig); 311 submit_bio_noacct(*bio_orig); 312 *bio_orig = bio; 313 } 314 bio = bounce_clone_bio(*bio_orig, GFP_NOIO, passthrough ? NULL : 315 &bounce_bio_set); 316 317 /* 318 * Bvec table can't be updated by bio_for_each_segment_all(), 319 * so retrieve bvec from the table directly. This way is safe 320 * because the 'bio' is single-page bvec. 321 */ 322 for (i = 0, to = bio->bi_io_vec; i < bio->bi_vcnt; to++, i++) { 323 struct page *page = to->bv_page; 324 325 if (page_to_pfn(page) <= q->limits.bounce_pfn) 326 continue; 327 328 to->bv_page = mempool_alloc(pool, q->bounce_gfp); 329 inc_zone_page_state(to->bv_page, NR_BOUNCE); 330 331 if (rw == WRITE) { 332 char *vto, *vfrom; 333 334 flush_dcache_page(page); 335 336 vto = page_address(to->bv_page) + to->bv_offset; 337 vfrom = kmap_atomic(page) + to->bv_offset; 338 memcpy(vto, vfrom, to->bv_len); 339 kunmap_atomic(vfrom); 340 } 341 } 342 343 trace_block_bio_bounce(*bio_orig); 344 345 bio->bi_flags |= (1 << BIO_BOUNCED); 346 347 if (pool == &page_pool) { 348 bio->bi_end_io = bounce_end_io_write; 349 if (rw == READ) 350 bio->bi_end_io = bounce_end_io_read; 351 } else { 352 bio->bi_end_io = bounce_end_io_write_isa; 353 if (rw == READ) 354 bio->bi_end_io = bounce_end_io_read_isa; 355 } 356 357 bio->bi_private = *bio_orig; 358 *bio_orig = bio; 359 } 360 361 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) 362 { 363 mempool_t *pool; 364 365 /* 366 * Data-less bio, nothing to bounce 367 */ 368 if (!bio_has_data(*bio_orig)) 369 return; 370 371 /* 372 * for non-isa bounce case, just check if the bounce pfn is equal 373 * to or bigger than the highest pfn in the system -- in that case, 374 * don't waste time iterating over bio segments 375 */ 376 if (!(q->bounce_gfp & GFP_DMA)) { 377 if (q->limits.bounce_pfn >= blk_max_pfn) 378 return; 379 pool = &page_pool; 380 } else { 381 BUG_ON(!mempool_initialized(&isa_page_pool)); 382 pool = &isa_page_pool; 383 } 384 385 /* 386 * slow path 387 */ 388 __blk_queue_bounce(q, bio_orig, pool); 389 } 390