root/block/bounce.c

DEFINITIONS

1. init_bounce_bioset
2. init_emergency_pool
3. bounce_copy_vec
4. mempool_alloc_pages_isa
5. init_emergency_isa_pool
6. copy_to_high_bio_irq
7. bounce_end_io
8. bounce_end_io_write
9. bounce_end_io_write_isa
10. __bounce_end_io_read
11. bounce_end_io_read
12. bounce_end_io_read_isa
13. bounce_clone_bio
14. __blk_queue_bounce
15. blk_queue_bounce

   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/memblock.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 static void init_bounce_bioset(void)
  35 {
  36         static bool bounce_bs_setup;
  37         int ret;
  38 
  39         if (bounce_bs_setup)
  40                 return;
  41 
  42         ret = bioset_init(&bounce_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
  43         BUG_ON(ret);
  44         if (bioset_integrity_create(&bounce_bio_set, BIO_POOL_SIZE))
  45                 BUG_ON(1);
  46 
  47         ret = bioset_init(&bounce_bio_split, BIO_POOL_SIZE, 0, 0);
  48         BUG_ON(ret);
  49         bounce_bs_setup = true;
  50 }
  51 
  52 #if defined(CONFIG_HIGHMEM)
  53 static __init int init_emergency_pool(void)
  54 {
  55         int ret;
  56 #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG)
  57         if (max_pfn <= max_low_pfn)
  58                 return 0;
  59 #endif
  60 
  61         ret = mempool_init_page_pool(&page_pool, POOL_SIZE, 0);
  62         BUG_ON(ret);
  63         pr_info("pool size: %d pages\n", POOL_SIZE);
  64 
  65         init_bounce_bioset();
  66         return 0;
  67 }
  68 
  69 __initcall(init_emergency_pool);
  70 #endif
  71 
  72 #ifdef CONFIG_HIGHMEM
  73 /*
  74  * highmem version, map in to vec
  75  */
  76 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
  77 {
  78         unsigned char *vto;
  79 
  80         vto = kmap_atomic(to->bv_page);
  81         memcpy(vto + to->bv_offset, vfrom, to->bv_len);
  82         kunmap_atomic(vto);
  83 }
  84 
  85 #else /* CONFIG_HIGHMEM */
  86 
  87 #define bounce_copy_vec(to, vfrom)      \
  88         memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
  89 
  90 #endif /* CONFIG_HIGHMEM */
  91 
  92 /*
  93  * allocate pages in the DMA region for the ISA pool
  94  */
  95 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
  96 {
  97         return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
  98 }
  99 
 100 static DEFINE_MUTEX(isa_mutex);
 101 
 102 /*
 103  * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
 104  * as the max address, so check if the pool has already been created.
 105  */
 106 int init_emergency_isa_pool(void)
 107 {
 108         int ret;
 109 
 110         mutex_lock(&isa_mutex);
 111 
 112         if (mempool_initialized(&isa_page_pool)) {
 113                 mutex_unlock(&isa_mutex);
 114                 return 0;
 115         }
 116 
 117         ret = mempool_init(&isa_page_pool, ISA_POOL_SIZE, mempool_alloc_pages_isa,
 118                            mempool_free_pages, (void *) 0);
 119         BUG_ON(ret);
 120 
 121         pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE);
 122         init_bounce_bioset();
 123         mutex_unlock(&isa_mutex);
 124         return 0;
 125 }
 126 
 127 /*
 128  * Simple bounce buffer support for highmem pages. Depending on the
 129  * queue gfp mask set, *to may or may not be a highmem page. kmap it
 130  * always, it will do the Right Thing
 131  */
 132 static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
 133 {
 134         unsigned char *vfrom;
 135         struct bio_vec tovec, fromvec;
 136         struct bvec_iter iter;
 137         /*
 138          * The bio of @from is created by bounce, so we can iterate
 139          * its bvec from start to end, but the @from->bi_iter can't be
 140          * trusted because it might be changed by splitting.
 141          */
 142         struct bvec_iter from_iter = BVEC_ITER_ALL_INIT;
 143 
 144         bio_for_each_segment(tovec, to, iter) {
 145                 fromvec = bio_iter_iovec(from, from_iter);
 146                 if (tovec.bv_page != fromvec.bv_page) {
 147                         /*
 148                          * fromvec->bv_offset and fromvec->bv_len might have
 149                          * been modified by the block layer, so use the original
 150                          * copy, bounce_copy_vec already uses tovec->bv_len
 151                          */
 152                         vfrom = page_address(fromvec.bv_page) +
 153                                 tovec.bv_offset;
 154 
 155                         bounce_copy_vec(&tovec, vfrom);
 156                         flush_dcache_page(tovec.bv_page);
 157                 }
 158                 bio_advance_iter(from, &from_iter, tovec.bv_len);
 159         }
 160 }
 161 
 162 static void bounce_end_io(struct bio *bio, mempool_t *pool)
 163 {
 164         struct bio *bio_orig = bio->bi_private;
 165         struct bio_vec *bvec, orig_vec;
 166         struct bvec_iter orig_iter = bio_orig->bi_iter;
 167         struct bvec_iter_all iter_all;
 168 
 169         /*
 170          * free up bounce indirect pages used
 171          */
 172         bio_for_each_segment_all(bvec, bio, iter_all) {
 173                 orig_vec = bio_iter_iovec(bio_orig, orig_iter);
 174                 if (bvec->bv_page != orig_vec.bv_page) {
 175                         dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
 176                         mempool_free(bvec->bv_page, pool);
 177                 }
 178                 bio_advance_iter(bio_orig, &orig_iter, orig_vec.bv_len);
 179         }
 180 
 181         bio_orig->bi_status = bio->bi_status;
 182         bio_endio(bio_orig);
 183         bio_put(bio);
 184 }
 185 
 186 static void bounce_end_io_write(struct bio *bio)
 187 {
 188         bounce_end_io(bio, &page_pool);
 189 }
 190 
 191 static void bounce_end_io_write_isa(struct bio *bio)
 192 {
 193 
 194         bounce_end_io(bio, &isa_page_pool);
 195 }
 196 
 197 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool)
 198 {
 199         struct bio *bio_orig = bio->bi_private;
 200 
 201         if (!bio->bi_status)
 202                 copy_to_high_bio_irq(bio_orig, bio);
 203 
 204         bounce_end_io(bio, pool);
 205 }
 206 
 207 static void bounce_end_io_read(struct bio *bio)
 208 {
 209         __bounce_end_io_read(bio, &page_pool);
 210 }
 211 
 212 static void bounce_end_io_read_isa(struct bio *bio)
 213 {
 214         __bounce_end_io_read(bio, &isa_page_pool);
 215 }
 216 
 217 static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,
 218                 struct bio_set *bs)
 219 {
 220         struct bvec_iter iter;
 221         struct bio_vec bv;
 222         struct bio *bio;
 223 
 224         /*
 225          * Pre immutable biovecs, __bio_clone() used to just do a memcpy from
 226          * bio_src->bi_io_vec to bio->bi_io_vec.
 227          *
 228          * We can't do that anymore, because:
 229          *
 230          *  - The point of cloning the biovec is to produce a bio with a biovec
 231          *    the caller can modify: bi_idx and bi_bvec_done should be 0.
 232          *
 233          *  - The original bio could've had more than BIO_MAX_PAGES biovecs; if
 234          *    we tried to clone the whole thing bio_alloc_bioset() would fail.
 235          *    But the clone should succeed as long as the number of biovecs we
 236          *    actually need to allocate is fewer than BIO_MAX_PAGES.
 237          *
 238          *  - Lastly, bi_vcnt should not be looked at or relied upon by code
 239          *    that does not own the bio - reason being drivers don't use it for
 240          *    iterating over the biovec anymore, so expecting it to be kept up
 241          *    to date (i.e. for clones that share the parent biovec) is just
 242          *    asking for trouble and would force extra work on
 243          *    __bio_clone_fast() anyways.
 244          */
 245 
 246         bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
 247         if (!bio)
 248                 return NULL;
 249         bio->bi_disk            = bio_src->bi_disk;
 250         bio->bi_opf             = bio_src->bi_opf;
 251         bio->bi_ioprio          = bio_src->bi_ioprio;
 252         bio->bi_write_hint      = bio_src->bi_write_hint;
 253         bio->bi_iter.bi_sector  = bio_src->bi_iter.bi_sector;
 254         bio->bi_iter.bi_size    = bio_src->bi_iter.bi_size;
 255 
 256         switch (bio_op(bio)) {
 257         case REQ_OP_DISCARD:
 258         case REQ_OP_SECURE_ERASE:
 259         case REQ_OP_WRITE_ZEROES:
 260                 break;
 261         case REQ_OP_WRITE_SAME:
 262                 bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
 263                 break;
 264         default:
 265                 bio_for_each_segment(bv, bio_src, iter)
 266                         bio->bi_io_vec[bio->bi_vcnt++] = bv;
 267                 break;
 268         }
 269 
 270         if (bio_integrity(bio_src)) {
 271                 int ret;
 272 
 273                 ret = bio_integrity_clone(bio, bio_src, gfp_mask);
 274                 if (ret < 0) {
 275                         bio_put(bio);
 276                         return NULL;
 277                 }
 278         }
 279 
 280         bio_clone_blkg_association(bio, bio_src);
 281         blkcg_bio_issue_init(bio);
 282 
 283         return bio;
 284 }
 285 
 286 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
 287                                mempool_t *pool)
 288 {
 289         struct bio *bio;
 290         int rw = bio_data_dir(*bio_orig);
 291         struct bio_vec *to, from;
 292         struct bvec_iter iter;
 293         unsigned i = 0;
 294         bool bounce = false;
 295         int sectors = 0;
 296         bool passthrough = bio_is_passthrough(*bio_orig);
 297 
 298         bio_for_each_segment(from, *bio_orig, iter) {
 299                 if (i++ < BIO_MAX_PAGES)
 300                         sectors += from.bv_len >> 9;
 301                 if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn)
 302                         bounce = true;
 303         }
 304         if (!bounce)
 305                 return;
 306 
 307         if (!passthrough && sectors < bio_sectors(*bio_orig)) {
 308                 bio = bio_split(*bio_orig, sectors, GFP_NOIO, &bounce_bio_split);
 309                 bio_chain(bio, *bio_orig);
 310                 generic_make_request(*bio_orig);
 311                 *bio_orig = bio;
 312         }
 313         bio = bounce_clone_bio(*bio_orig, GFP_NOIO, passthrough ? NULL :
 314                         &bounce_bio_set);
 315 
 316         /*
 317          * Bvec table can't be updated by bio_for_each_segment_all(),
 318          * so retrieve bvec from the table directly. This way is safe
 319          * because the 'bio' is single-page bvec.
 320          */
 321         for (i = 0, to = bio->bi_io_vec; i < bio->bi_vcnt; to++, i++) {
 322                 struct page *page = to->bv_page;
 323 
 324                 if (page_to_pfn(page) <= q->limits.bounce_pfn)
 325                         continue;
 326 
 327                 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
 328                 inc_zone_page_state(to->bv_page, NR_BOUNCE);
 329 
 330                 if (rw == WRITE) {
 331                         char *vto, *vfrom;
 332 
 333                         flush_dcache_page(page);
 334 
 335                         vto = page_address(to->bv_page) + to->bv_offset;
 336                         vfrom = kmap_atomic(page) + to->bv_offset;
 337                         memcpy(vto, vfrom, to->bv_len);
 338                         kunmap_atomic(vfrom);
 339                 }
 340         }
 341 
 342         trace_block_bio_bounce(q, *bio_orig);
 343 
 344         bio->bi_flags |= (1 << BIO_BOUNCED);
 345 
 346         if (pool == &page_pool) {
 347                 bio->bi_end_io = bounce_end_io_write;
 348                 if (rw == READ)
 349                         bio->bi_end_io = bounce_end_io_read;
 350         } else {
 351                 bio->bi_end_io = bounce_end_io_write_isa;
 352                 if (rw == READ)
 353                         bio->bi_end_io = bounce_end_io_read_isa;
 354         }
 355 
 356         bio->bi_private = *bio_orig;
 357         *bio_orig = bio;
 358 }
 359 
 360 void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
 361 {
 362         mempool_t *pool;
 363 
 364         /*
 365          * Data-less bio, nothing to bounce
 366          */
 367         if (!bio_has_data(*bio_orig))
 368                 return;
 369 
 370         /*
 371          * for non-isa bounce case, just check if the bounce pfn is equal
 372          * to or bigger than the highest pfn in the system -- in that case,
 373          * don't waste time iterating over bio segments
 374          */
 375         if (!(q->bounce_gfp & GFP_DMA)) {
 376                 if (q->limits.bounce_pfn >= blk_max_pfn)
 377                         return;
 378                 pool = &page_pool;
 379         } else {
 380                 BUG_ON(!mempool_initialized(&isa_page_pool));
 381                 pool = &isa_page_pool;
 382         }
 383 
 384         /*
 385          * slow path
 386          */
 387         __blk_queue_bounce(q, bio_orig, pool);
 388 }