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 void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, 199 mempool_t *pool) 200 { 201 struct bio *bio; 202 int rw = bio_data_dir(*bio_orig); 203 struct bio_vec *to, from; 204 struct bvec_iter iter; 205 unsigned i = 0; 206 bool bounce = false; 207 int sectors = 0; 208 bool passthrough = bio_is_passthrough(*bio_orig); 209 210 bio_for_each_segment(from, *bio_orig, iter) { 211 if (i++ < BIO_MAX_PAGES) 212 sectors += from.bv_len >> 9; 213 if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn) 214 bounce = true; 215 } 216 if (!bounce) 217 return; 218 219 if (!passthrough && sectors < bio_sectors(*bio_orig)) { 220 bio = bio_split(*bio_orig, sectors, GFP_NOIO, &bounce_bio_split); 221 bio_chain(bio, *bio_orig); 222 generic_make_request(*bio_orig); 223 *bio_orig = bio; 224 } 225 bio = bio_clone_bioset(*bio_orig, GFP_NOIO, passthrough ? NULL : 226 &bounce_bio_set); 227 228 bio_for_each_segment_all(to, bio, i) { 229 struct page *page = to->bv_page; 230 231 if (page_to_pfn(page) <= q->limits.bounce_pfn) 232 continue; 233 234 to->bv_page = mempool_alloc(pool, q->bounce_gfp); 235 inc_zone_page_state(to->bv_page, NR_BOUNCE); 236 237 if (rw == WRITE) { 238 char *vto, *vfrom; 239 240 flush_dcache_page(page); 241 242 vto = page_address(to->bv_page) + to->bv_offset; 243 vfrom = kmap_atomic(page) + to->bv_offset; 244 memcpy(vto, vfrom, to->bv_len); 245 kunmap_atomic(vfrom); 246 } 247 } 248 249 trace_block_bio_bounce(q, *bio_orig); 250 251 bio->bi_flags |= (1 << BIO_BOUNCED); 252 253 if (pool == &page_pool) { 254 bio->bi_end_io = bounce_end_io_write; 255 if (rw == READ) 256 bio->bi_end_io = bounce_end_io_read; 257 } else { 258 bio->bi_end_io = bounce_end_io_write_isa; 259 if (rw == READ) 260 bio->bi_end_io = bounce_end_io_read_isa; 261 } 262 263 bio->bi_private = *bio_orig; 264 *bio_orig = bio; 265 } 266 267 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) 268 { 269 mempool_t *pool; 270 271 /* 272 * Data-less bio, nothing to bounce 273 */ 274 if (!bio_has_data(*bio_orig)) 275 return; 276 277 /* 278 * for non-isa bounce case, just check if the bounce pfn is equal 279 * to or bigger than the highest pfn in the system -- in that case, 280 * don't waste time iterating over bio segments 281 */ 282 if (!(q->bounce_gfp & GFP_DMA)) { 283 if (q->limits.bounce_pfn >= blk_max_pfn) 284 return; 285 pool = &page_pool; 286 } else { 287 BUG_ON(!mempool_initialized(&isa_page_pool)); 288 pool = &isa_page_pool; 289 } 290 291 /* 292 * slow path 293 */ 294 __blk_queue_bounce(q, bio_orig, pool); 295 } 296