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) || defined(CONFIG_NEED_BOUNCE_POOL) 35 static __init int init_emergency_pool(void) 36 { 37 #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG) 38 if (max_pfn <= max_low_pfn) 39 return 0; 40 #endif 41 42 page_pool = mempool_create_page_pool(POOL_SIZE, 0); 43 BUG_ON(!page_pool); 44 pr_info("pool size: %d pages\n", POOL_SIZE); 45 46 bounce_bio_set = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); 47 BUG_ON(!bounce_bio_set); 48 if (bioset_integrity_create(bounce_bio_set, BIO_POOL_SIZE)) 49 BUG_ON(1); 50 51 bounce_bio_split = bioset_create(BIO_POOL_SIZE, 0, 0); 52 BUG_ON(!bounce_bio_split); 53 54 return 0; 55 } 56 57 __initcall(init_emergency_pool); 58 #endif 59 60 #ifdef CONFIG_HIGHMEM 61 /* 62 * highmem version, map in to vec 63 */ 64 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) 65 { 66 unsigned long flags; 67 unsigned char *vto; 68 69 local_irq_save(flags); 70 vto = kmap_atomic(to->bv_page); 71 memcpy(vto + to->bv_offset, vfrom, to->bv_len); 72 kunmap_atomic(vto); 73 local_irq_restore(flags); 74 } 75 76 #else /* CONFIG_HIGHMEM */ 77 78 #define bounce_copy_vec(to, vfrom) \ 79 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) 80 81 #endif /* CONFIG_HIGHMEM */ 82 83 /* 84 * allocate pages in the DMA region for the ISA pool 85 */ 86 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data) 87 { 88 return mempool_alloc_pages(gfp_mask | GFP_DMA, data); 89 } 90 91 /* 92 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA 93 * as the max address, so check if the pool has already been created. 94 */ 95 int init_emergency_isa_pool(void) 96 { 97 if (isa_page_pool) 98 return 0; 99 100 isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa, 101 mempool_free_pages, (void *) 0); 102 BUG_ON(!isa_page_pool); 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 = from->bi_io_vec; 117 struct bvec_iter iter; 118 119 bio_for_each_segment(tovec, to, iter) { 120 if (tovec.bv_page != fromvec->bv_page) { 121 /* 122 * fromvec->bv_offset and fromvec->bv_len might have 123 * been modified by the block layer, so use the original 124 * copy, bounce_copy_vec already uses tovec->bv_len 125 */ 126 vfrom = page_address(fromvec->bv_page) + 127 tovec.bv_offset; 128 129 bounce_copy_vec(&tovec, vfrom); 130 flush_dcache_page(tovec.bv_page); 131 } 132 133 fromvec++; 134 } 135 } 136 137 static void bounce_end_io(struct bio *bio, mempool_t *pool) 138 { 139 struct bio *bio_orig = bio->bi_private; 140 struct bio_vec *bvec, *org_vec; 141 int i; 142 int start = bio_orig->bi_iter.bi_idx; 143 144 /* 145 * free up bounce indirect pages used 146 */ 147 bio_for_each_segment_all(bvec, bio, i) { 148 org_vec = bio_orig->bi_io_vec + i + start; 149 150 if (bvec->bv_page == org_vec->bv_page) 151 continue; 152 153 dec_zone_page_state(bvec->bv_page, NR_BOUNCE); 154 mempool_free(bvec->bv_page, pool); 155 } 156 157 bio_orig->bi_status = bio->bi_status; 158 bio_endio(bio_orig); 159 bio_put(bio); 160 } 161 162 static void bounce_end_io_write(struct bio *bio) 163 { 164 bounce_end_io(bio, page_pool); 165 } 166 167 static void bounce_end_io_write_isa(struct bio *bio) 168 { 169 170 bounce_end_io(bio, isa_page_pool); 171 } 172 173 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool) 174 { 175 struct bio *bio_orig = bio->bi_private; 176 177 if (!bio->bi_status) 178 copy_to_high_bio_irq(bio_orig, bio); 179 180 bounce_end_io(bio, pool); 181 } 182 183 static void bounce_end_io_read(struct bio *bio) 184 { 185 __bounce_end_io_read(bio, page_pool); 186 } 187 188 static void bounce_end_io_read_isa(struct bio *bio) 189 { 190 __bounce_end_io_read(bio, isa_page_pool); 191 } 192 193 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, 194 mempool_t *pool) 195 { 196 struct bio *bio; 197 int rw = bio_data_dir(*bio_orig); 198 struct bio_vec *to, from; 199 struct bvec_iter iter; 200 unsigned i = 0; 201 bool bounce = false; 202 int sectors = 0; 203 204 bio_for_each_segment(from, *bio_orig, iter) { 205 if (i++ < BIO_MAX_PAGES) 206 sectors += from.bv_len >> 9; 207 if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn) 208 bounce = true; 209 } 210 if (!bounce) 211 return; 212 213 if (sectors < bio_sectors(*bio_orig)) { 214 bio = bio_split(*bio_orig, sectors, GFP_NOIO, bounce_bio_split); 215 bio_chain(bio, *bio_orig); 216 generic_make_request(*bio_orig); 217 *bio_orig = bio; 218 } 219 bio = bio_clone_bioset(*bio_orig, GFP_NOIO, bounce_bio_set); 220 221 bio_for_each_segment_all(to, bio, i) { 222 struct page *page = to->bv_page; 223 224 if (page_to_pfn(page) <= q->limits.bounce_pfn) 225 continue; 226 227 to->bv_page = mempool_alloc(pool, q->bounce_gfp); 228 inc_zone_page_state(to->bv_page, NR_BOUNCE); 229 230 if (rw == WRITE) { 231 char *vto, *vfrom; 232 233 flush_dcache_page(page); 234 235 vto = page_address(to->bv_page) + to->bv_offset; 236 vfrom = kmap_atomic(page) + to->bv_offset; 237 memcpy(vto, vfrom, to->bv_len); 238 kunmap_atomic(vfrom); 239 } 240 } 241 242 trace_block_bio_bounce(q, *bio_orig); 243 244 bio->bi_flags |= (1 << BIO_BOUNCED); 245 246 if (pool == page_pool) { 247 bio->bi_end_io = bounce_end_io_write; 248 if (rw == READ) 249 bio->bi_end_io = bounce_end_io_read; 250 } else { 251 bio->bi_end_io = bounce_end_io_write_isa; 252 if (rw == READ) 253 bio->bi_end_io = bounce_end_io_read_isa; 254 } 255 256 bio->bi_private = *bio_orig; 257 *bio_orig = bio; 258 } 259 260 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) 261 { 262 mempool_t *pool; 263 264 /* 265 * Data-less bio, nothing to bounce 266 */ 267 if (!bio_has_data(*bio_orig)) 268 return; 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 (q->limits.bounce_pfn >= blk_max_pfn) 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); 288 } 289