block/bounce.c

   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         bool passthrough = bio_is_passthrough(*bio_orig);
 204
 205         bio_for_each_segment(from, *bio_orig, iter) {
 206                 if (i++ < BIO_MAX_PAGES)
 207                         sectors += from.bv_len >> 9;
 208                 if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn)
 209                         bounce = true;
 210         }
 211         if (!bounce)
 212                 return;
 213
 214         if (!passthrough && sectors < bio_sectors(*bio_orig)) {
 215                 bio = bio_split(*bio_orig, sectors, GFP_NOIO, bounce_bio_split);
 216                 bio_chain(bio, *bio_orig);
 217                 generic_make_request(*bio_orig);
 218                 *bio_orig = bio;
 219         }
 220         bio = bio_clone_bioset(*bio_orig, GFP_NOIO, passthrough ? NULL :
 221                         bounce_bio_set);
 222
 223         bio_for_each_segment_all(to, bio, i) {
 224                 struct page *page = to->bv_page;
 225
 226                 if (page_to_pfn(page) <= q->limits.bounce_pfn)
 227                         continue;
 228
 229                 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
 230                 inc_zone_page_state(to->bv_page, NR_BOUNCE);
 231
 232                 if (rw == WRITE) {
 233                         char *vto, *vfrom;
 234
 235                         flush_dcache_page(page);
 236
 237                         vto = page_address(to->bv_page) + to->bv_offset;
 238                         vfrom = kmap_atomic(page) + to->bv_offset;
 239                         memcpy(vto, vfrom, to->bv_len);
 240                         kunmap_atomic(vfrom);
 241                 }
 242         }
 243
 244         trace_block_bio_bounce(q, *bio_orig);
 245
 246         bio->bi_flags |= (1 << BIO_BOUNCED);
 247
 248         if (pool == page_pool) {
 249                 bio->bi_end_io = bounce_end_io_write;
 250                 if (rw == READ)
 251                         bio->bi_end_io = bounce_end_io_read;
 252         } else {
 253                 bio->bi_end_io = bounce_end_io_write_isa;
 254                 if (rw == READ)
 255                         bio->bi_end_io = bounce_end_io_read_isa;
 256         }
 257
 258         bio->bi_private = *bio_orig;
 259         *bio_orig = bio;
 260 }
 261
 262 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
 263 {
 264         mempool_t *pool;
 265
 266         /*
 267          * Data-less bio, nothing to bounce
 268          */
 269         if (!bio_has_data(*bio_orig))
 270                 return;
 271
 272         /*
 273          * for non-isa bounce case, just check if the bounce pfn is equal
 274          * to or bigger than the highest pfn in the system -- in that case,
 275          * don't waste time iterating over bio segments
 276          */
 277         if (!(q->bounce_gfp & GFP_DMA)) {
 278                 if (q->limits.bounce_pfn >= blk_max_pfn)
 279                         return;
 280                 pool = page_pool;
 281         } else {
 282                 BUG_ON(!isa_page_pool);
 283                 pool = isa_page_pool;
 284         }
 285
 286         /*
 287          * slow path
 288          */
 289         __blk_queue_bounce(q, bio_orig, pool);
 290 }