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 #include "blk.h" 26 27 #define POOL_SIZE 64 28 #define ISA_POOL_SIZE 16 29 30 static struct bio_set *bounce_bio_set, *bounce_bio_split; 31 static mempool_t *page_pool, *isa_page_pool; 32 33 #if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL) 34 static __init int init_emergency_pool(void) 35 { 36 #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG) 37 if (max_pfn <= max_low_pfn) 38 return 0; 39 #endif 40 41 page_pool = mempool_create_page_pool(POOL_SIZE, 0); 42 BUG_ON(!page_pool); 43 pr_info("pool size: %d pages\n", POOL_SIZE); 44 45 bounce_bio_set = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); 46 BUG_ON(!bounce_bio_set); 47 if (bioset_integrity_create(bounce_bio_set, BIO_POOL_SIZE)) 48 BUG_ON(1); 49 50 bounce_bio_split = bioset_create(BIO_POOL_SIZE, 0, 0); 51 BUG_ON(!bounce_bio_split); 52 53 return 0; 54 } 55 56 __initcall(init_emergency_pool); 57 #endif 58 59 #ifdef CONFIG_HIGHMEM 60 /* 61 * highmem version, map in to vec 62 */ 63 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) 64 { 65 unsigned long flags; 66 unsigned char *vto; 67 68 local_irq_save(flags); 69 vto = kmap_atomic(to->bv_page); 70 memcpy(vto + to->bv_offset, vfrom, to->bv_len); 71 kunmap_atomic(vto); 72 local_irq_restore(flags); 73 } 74 75 #else /* CONFIG_HIGHMEM */ 76 77 #define bounce_copy_vec(to, vfrom) \ 78 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) 79 80 #endif /* CONFIG_HIGHMEM */ 81 82 /* 83 * allocate pages in the DMA region for the ISA pool 84 */ 85 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data) 86 { 87 return mempool_alloc_pages(gfp_mask | GFP_DMA, data); 88 } 89 90 /* 91 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA 92 * as the max address, so check if the pool has already been created. 93 */ 94 int init_emergency_isa_pool(void) 95 { 96 if (isa_page_pool) 97 return 0; 98 99 isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa, 100 mempool_free_pages, (void *) 0); 101 BUG_ON(!isa_page_pool); 102 103 pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE); 104 return 0; 105 } 106 107 /* 108 * Simple bounce buffer support for highmem pages. Depending on the 109 * queue gfp mask set, *to may or may not be a highmem page. kmap it 110 * always, it will do the Right Thing 111 */ 112 static void copy_to_high_bio_irq(struct bio *to, struct bio *from) 113 { 114 unsigned char *vfrom; 115 struct bio_vec tovec, *fromvec = from->bi_io_vec; 116 struct bvec_iter iter; 117 118 bio_for_each_segment(tovec, to, iter) { 119 if (tovec.bv_page != fromvec->bv_page) { 120 /* 121 * fromvec->bv_offset and fromvec->bv_len might have 122 * been modified by the block layer, so use the original 123 * copy, bounce_copy_vec already uses tovec->bv_len 124 */ 125 vfrom = page_address(fromvec->bv_page) + 126 tovec.bv_offset; 127 128 bounce_copy_vec(&tovec, vfrom); 129 flush_dcache_page(tovec.bv_page); 130 } 131 132 fromvec++; 133 } 134 } 135 136 static void bounce_end_io(struct bio *bio, mempool_t *pool) 137 { 138 struct bio *bio_orig = bio->bi_private; 139 struct bio_vec *bvec, *org_vec; 140 int i; 141 int start = bio_orig->bi_iter.bi_idx; 142 143 /* 144 * free up bounce indirect pages used 145 */ 146 bio_for_each_segment_all(bvec, bio, i) { 147 org_vec = bio_orig->bi_io_vec + i + start; 148 149 if (bvec->bv_page == org_vec->bv_page) 150 continue; 151 152 dec_zone_page_state(bvec->bv_page, NR_BOUNCE); 153 mempool_free(bvec->bv_page, pool); 154 } 155 156 bio_orig->bi_status = bio->bi_status; 157 bio_endio(bio_orig); 158 bio_put(bio); 159 } 160 161 static void bounce_end_io_write(struct bio *bio) 162 { 163 bounce_end_io(bio, page_pool); 164 } 165 166 static void bounce_end_io_write_isa(struct bio *bio) 167 { 168 169 bounce_end_io(bio, isa_page_pool); 170 } 171 172 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool) 173 { 174 struct bio *bio_orig = bio->bi_private; 175 176 if (!bio->bi_status) 177 copy_to_high_bio_irq(bio_orig, bio); 178 179 bounce_end_io(bio, pool); 180 } 181 182 static void bounce_end_io_read(struct bio *bio) 183 { 184 __bounce_end_io_read(bio, page_pool); 185 } 186 187 static void bounce_end_io_read_isa(struct bio *bio) 188 { 189 __bounce_end_io_read(bio, isa_page_pool); 190 } 191 192 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, 193 mempool_t *pool) 194 { 195 struct bio *bio; 196 int rw = bio_data_dir(*bio_orig); 197 struct bio_vec *to, from; 198 struct bvec_iter iter; 199 unsigned i = 0; 200 bool bounce = false; 201 int sectors = 0; 202 203 bio_for_each_segment(from, *bio_orig, iter) { 204 if (i++ < BIO_MAX_PAGES) 205 sectors += from.bv_len >> 9; 206 if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn) 207 bounce = true; 208 } 209 if (!bounce) 210 return; 211 212 if (sectors < bio_sectors(*bio_orig)) { 213 bio = bio_split(*bio_orig, sectors, GFP_NOIO, bounce_bio_split); 214 bio_chain(bio, *bio_orig); 215 generic_make_request(*bio_orig); 216 *bio_orig = bio; 217 } 218 bio = bio_clone_bioset(*bio_orig, GFP_NOIO, bounce_bio_set); 219 220 bio_for_each_segment_all(to, bio, i) { 221 struct page *page = to->bv_page; 222 223 if (page_to_pfn(page) <= q->limits.bounce_pfn) 224 continue; 225 226 to->bv_page = mempool_alloc(pool, q->bounce_gfp); 227 inc_zone_page_state(to->bv_page, NR_BOUNCE); 228 229 if (rw == WRITE) { 230 char *vto, *vfrom; 231 232 flush_dcache_page(page); 233 234 vto = page_address(to->bv_page) + to->bv_offset; 235 vfrom = kmap_atomic(page) + to->bv_offset; 236 memcpy(vto, vfrom, to->bv_len); 237 kunmap_atomic(vfrom); 238 } 239 } 240 241 trace_block_bio_bounce(q, *bio_orig); 242 243 bio->bi_flags |= (1 << BIO_BOUNCED); 244 245 if (pool == page_pool) { 246 bio->bi_end_io = bounce_end_io_write; 247 if (rw == READ) 248 bio->bi_end_io = bounce_end_io_read; 249 } else { 250 bio->bi_end_io = bounce_end_io_write_isa; 251 if (rw == READ) 252 bio->bi_end_io = bounce_end_io_read_isa; 253 } 254 255 bio->bi_private = *bio_orig; 256 *bio_orig = bio; 257 } 258 259 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) 260 { 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 /* 270 * for non-isa bounce case, just check if the bounce pfn is equal 271 * to or bigger than the highest pfn in the system -- in that case, 272 * don't waste time iterating over bio segments 273 */ 274 if (!(q->bounce_gfp & GFP_DMA)) { 275 if (q->limits.bounce_pfn >= blk_max_pfn) 276 return; 277 pool = page_pool; 278 } else { 279 BUG_ON(!isa_page_pool); 280 pool = isa_page_pool; 281 } 282 283 /* 284 * slow path 285 */ 286 __blk_queue_bounce(q, bio_orig, pool); 287 } 288