mm/bounce.c

   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/bio.h>
  10 #include <linux/pagemap.h>
  11 #include <linux/mempool.h>
  12 #include <linux/blkdev.h>
  13 #include <linux/init.h>
  14 #include <linux/hash.h>
  15 #include <linux/highmem.h>
  16 #include <linux/blktrace_api.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
  24 static mempool_t *page_pool, *isa_page_pool;
  25
  26 #ifdef CONFIG_HIGHMEM
  27 static __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  */
  48 static 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  */
  70 static 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  */
  79 int 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  */
  97 static 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                 flush_dcache_page(tovec->bv_page);
 120                 bounce_copy_vec(tovec, vfrom);
 121         }
 122 }
 123
 124 static 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
 149 static void bounce_end_io_write(struct bio *bio, int err)
 150 {
 151         bounce_end_io(bio, page_pool, err);
 152 }
 153
 154 static void bounce_end_io_write_isa(struct bio *bio, int err)
 155 {
 156
 157         bounce_end_io(bio, isa_page_pool, err);
 158 }
 159
 160 static 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
 170 static void bounce_end_io_read(struct bio *bio, int err)
 171 {
 172         __bounce_end_io_read(bio, page_pool, err);
 173 }
 174
 175 static void bounce_end_io_read_isa(struct bio *bio, int err)
 176 {
 177         __bounce_end_io_read(bio, isa_page_pool, err);
 178 }
 179
 180 static 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
 270 void 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
 300 EXPORT_SYMBOL(blk_queue_bounce);