1/* bounce buffer handling for block devices 2 * 3 * - Split from highmem.c 4 */ 5 6#include <linux/mm.h> 7#include <linux/module.h> 8#include <linux/swap.h> 9#include <linux/gfp.h> 10#include <linux/bio.h> 11#include <linux/pagemap.h> 12#include <linux/mempool.h> 13#include <linux/blkdev.h> 14#include <linux/init.h> 15#include <linux/hash.h> 16#include <linux/highmem.h> 17#include <asm/tlbflush.h> 18 19#include <trace/events/block.h> 20 21#define POOL_SIZE 64 22#define ISA_POOL_SIZE 16 23 24static mempool_t *page_pool, *isa_page_pool; 25 26#ifdef CONFIG_HIGHMEM 27static __init int init_emergency_pool(void) 28{ 29 struct sysinfo i; 30 si_meminfo(&i); 31 si_swapinfo(&i); 32 33 if (!i.totalhigh) 34 return 0; 35 36 page_pool = mempool_create_page_pool(POOL_SIZE, 0); 37 BUG_ON(!page_pool); 38 printk("highmem bounce pool size: %d pages\n", POOL_SIZE); 39 40 return 0; 41} 42 43__initcall(init_emergency_pool); 44 45/* 46 * highmem version, map in to vec 47 */ 48static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) 49{ 50 unsigned long flags; 51 unsigned char *vto; 52 53 local_irq_save(flags); 54 vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ); 55 memcpy(vto + to->bv_offset, vfrom, to->bv_len); 56 kunmap_atomic(vto, KM_BOUNCE_READ); 57 local_irq_restore(flags); 58} 59 60#else /* CONFIG_HIGHMEM */ 61 62#define bounce_copy_vec(to, vfrom) \ 63 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) 64 65#endif /* CONFIG_HIGHMEM */ 66 67/* 68 * allocate pages in the DMA region for the ISA pool 69 */ 70static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data) 71{ 72 return mempool_alloc_pages(gfp_mask | GFP_DMA, data); 73} 74 75/* 76 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA 77 * as the max address, so check if the pool has already been created. 78 */ 79int init_emergency_isa_pool(void) 80{ 81 if (isa_page_pool) 82 return 0; 83 84 isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa, 85 mempool_free_pages, (void *) 0); 86 BUG_ON(!isa_page_pool); 87 88 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE); 89 return 0; 90} 91 92/* 93 * Simple bounce buffer support for highmem pages. Depending on the 94 * queue gfp mask set, *to may or may not be a highmem page. kmap it 95 * always, it will do the Right Thing 96 */ 97static void copy_to_high_bio_irq(struct bio *to, struct bio *from) 98{ 99 unsigned char *vfrom; 100 struct bio_vec *tovec, *fromvec; 101 int i; 102 103 __bio_for_each_segment(tovec, to, i, 0) { 104 fromvec = from->bi_io_vec + i; 105 106 /* 107 * not bounced 108 */ 109 if (tovec->bv_page == fromvec->bv_page) 110 continue; 111 112 /* 113 * fromvec->bv_offset and fromvec->bv_len might have been 114 * modified by the block layer, so use the original copy, 115 * bounce_copy_vec already uses tovec->bv_len 116 */ 117 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset; 118 119 bounce_copy_vec(tovec, vfrom); 120 flush_dcache_page(tovec->bv_page); 121 } 122} 123 124static void bounce_end_io(struct bio *bio, mempool_t *pool, int err) 125{ 126 struct bio *bio_orig = bio->bi_private; 127 struct bio_vec *bvec, *org_vec; 128 int i; 129 130 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags)) 131 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags); 132 133 /* 134 * free up bounce indirect pages used 135 */ 136 __bio_for_each_segment(bvec, bio, i, 0) { 137 org_vec = bio_orig->bi_io_vec + i; 138 if (bvec->bv_page == org_vec->bv_page) 139 continue; 140 141 dec_zone_page_state(bvec->bv_page, NR_BOUNCE); 142 mempool_free(bvec->bv_page, pool); 143 } 144 145 bio_endio(bio_orig, err); 146 bio_put(bio); 147} 148 149static void bounce_end_io_write(struct bio *bio, int err) 150{ 151 bounce_end_io(bio, page_pool, err); 152} 153 154static void bounce_end_io_write_isa(struct bio *bio, int err) 155{ 156 157 bounce_end_io(bio, isa_page_pool, err); 158} 159 160static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err) 161{ 162 struct bio *bio_orig = bio->bi_private; 163 164 if (test_bit(BIO_UPTODATE, &bio->bi_flags)) 165 copy_to_high_bio_irq(bio_orig, bio); 166 167 bounce_end_io(bio, pool, err); 168} 169 170static void bounce_end_io_read(struct bio *bio, int err) 171{ 172 __bounce_end_io_read(bio, page_pool, err); 173} 174 175static void bounce_end_io_read_isa(struct bio *bio, int err) 176{ 177 __bounce_end_io_read(bio, isa_page_pool, err); 178} 179 180static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, 181 mempool_t *pool) 182{ 183 struct page *page; 184 struct bio *bio = NULL; 185 int i, rw = bio_data_dir(*bio_orig); 186 struct bio_vec *to, *from; 187 188 bio_for_each_segment(from, *bio_orig, i) { 189 page = from->bv_page; 190 191 /* 192 * is destination page below bounce pfn? 193 */ 194 if (page_to_pfn(page) <= queue_bounce_pfn(q)) 195 continue; 196 197 /* 198 * irk, bounce it 199 */ 200 if (!bio) { 201 unsigned int cnt = (*bio_orig)->bi_vcnt; 202 203 bio = bio_alloc(GFP_NOIO, cnt); 204 memset(bio->bi_io_vec, 0, cnt * sizeof(struct bio_vec)); 205 } 206 207 208 to = bio->bi_io_vec + i; 209 210 to->bv_page = mempool_alloc(pool, q->bounce_gfp); 211 to->bv_len = from->bv_len; 212 to->bv_offset = from->bv_offset; 213 inc_zone_page_state(to->bv_page, NR_BOUNCE); 214 215 if (rw == WRITE) { 216 char *vto, *vfrom; 217 218 flush_dcache_page(from->bv_page); 219 vto = page_address(to->bv_page) + to->bv_offset; 220 vfrom = kmap(from->bv_page) + from->bv_offset; 221 memcpy(vto, vfrom, to->bv_len); 222 kunmap(from->bv_page); 223 } 224 } 225 226 /* 227 * no pages bounced 228 */ 229 if (!bio) 230 return; 231 232 trace_block_bio_bounce(q, *bio_orig); 233 234 /* 235 * at least one page was bounced, fill in possible non-highmem 236 * pages 237 */ 238 __bio_for_each_segment(from, *bio_orig, i, 0) { 239 to = bio_iovec_idx(bio, i); 240 if (!to->bv_page) { 241 to->bv_page = from->bv_page; 242 to->bv_len = from->bv_len; 243 to->bv_offset = from->bv_offset; 244 } 245 } 246 247 bio->bi_bdev = (*bio_orig)->bi_bdev; 248 bio->bi_flags |= (1 << BIO_BOUNCED); 249 bio->bi_sector = (*bio_orig)->bi_sector; 250 bio->bi_rw = (*bio_orig)->bi_rw; 251 252 bio->bi_vcnt = (*bio_orig)->bi_vcnt; 253 bio->bi_idx = (*bio_orig)->bi_idx; 254 bio->bi_size = (*bio_orig)->bi_size; 255 256 if (pool == page_pool) { 257 bio->bi_end_io = bounce_end_io_write; 258 if (rw == READ) 259 bio->bi_end_io = bounce_end_io_read; 260 } else { 261 bio->bi_end_io = bounce_end_io_write_isa; 262 if (rw == READ) 263 bio->bi_end_io = bounce_end_io_read_isa; 264 } 265 266 bio->bi_private = *bio_orig; 267 *bio_orig = bio; 268} 269 270void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) 271{ 272 mempool_t *pool; 273 274 /* 275 * Data-less bio, nothing to bounce 276 */ 277 if (!bio_has_data(*bio_orig)) 278 return; 279 280 /* 281 * for non-isa bounce case, just check if the bounce pfn is equal 282 * to or bigger than the highest pfn in the system -- in that case, 283 * don't waste time iterating over bio segments 284 */ 285 if (!(q->bounce_gfp & GFP_DMA)) { 286 if (queue_bounce_pfn(q) >= blk_max_pfn) 287 return; 288 pool = page_pool; 289 } else { 290 BUG_ON(!isa_page_pool); 291 pool = isa_page_pool; 292 } 293 294 /* 295 * slow path 296 */ 297 __blk_queue_bounce(q, bio_orig, pool); 298} 299 300EXPORT_SYMBOL(blk_queue_bounce); 301