block/bounce.c

   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 }