270 lines · c
1// SPDX-License-Identifier: GPL-2.02/* bounce buffer handling for block devices3 *4 * - Split from highmem.c5 */6 7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt8 9#include <linux/mm.h>10#include <linux/export.h>11#include <linux/swap.h>12#include <linux/gfp.h>13#include <linux/bio-integrity.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/printk.h>22#include <asm/tlbflush.h>23 24#include <trace/events/block.h>25#include "blk.h"26#include "blk-cgroup.h"27 28#define POOL_SIZE 6429#define ISA_POOL_SIZE 1630 31static struct bio_set bounce_bio_set, bounce_bio_split;32static mempool_t page_pool;33 34static 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 52static __init int init_emergency_pool(void)53{54 int ret;55 56#ifndef CONFIG_MEMORY_HOTPLUG57 if (max_pfn <= max_low_pfn)58 return 0;59#endif60 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 71/*72 * Simple bounce buffer support for highmem pages. Depending on the73 * queue gfp mask set, *to may or may not be a highmem page. kmap it74 * always, it will do the Right Thing75 */76static void copy_to_high_bio_irq(struct bio *to, struct bio *from)77{78 struct bio_vec tovec, fromvec;79 struct bvec_iter iter;80 /*81 * The bio of @from is created by bounce, so we can iterate82 * its bvec from start to end, but the @from->bi_iter can't be83 * trusted because it might be changed by splitting.84 */85 struct bvec_iter from_iter = BVEC_ITER_ALL_INIT;86 87 bio_for_each_segment(tovec, to, iter) {88 fromvec = bio_iter_iovec(from, from_iter);89 if (tovec.bv_page != fromvec.bv_page) {90 /*91 * fromvec->bv_offset and fromvec->bv_len might have92 * been modified by the block layer, so use the original93 * copy, bounce_copy_vec already uses tovec->bv_len94 */95 memcpy_to_bvec(&tovec, page_address(fromvec.bv_page) +96 tovec.bv_offset);97 }98 bio_advance_iter(from, &from_iter, tovec.bv_len);99 }100}101 102static void bounce_end_io(struct bio *bio)103{104 struct bio *bio_orig = bio->bi_private;105 struct bio_vec *bvec, orig_vec;106 struct bvec_iter orig_iter = bio_orig->bi_iter;107 struct bvec_iter_all iter_all;108 109 /*110 * free up bounce indirect pages used111 */112 bio_for_each_segment_all(bvec, bio, iter_all) {113 orig_vec = bio_iter_iovec(bio_orig, orig_iter);114 if (bvec->bv_page != orig_vec.bv_page) {115 dec_zone_page_state(bvec->bv_page, NR_BOUNCE);116 mempool_free(bvec->bv_page, &page_pool);117 }118 bio_advance_iter(bio_orig, &orig_iter, orig_vec.bv_len);119 }120 121 bio_orig->bi_status = bio->bi_status;122 bio_endio(bio_orig);123 bio_put(bio);124}125 126static void bounce_end_io_write(struct bio *bio)127{128 bounce_end_io(bio);129}130 131static void bounce_end_io_read(struct bio *bio)132{133 struct bio *bio_orig = bio->bi_private;134 135 if (!bio->bi_status)136 copy_to_high_bio_irq(bio_orig, bio);137 138 bounce_end_io(bio);139}140 141static struct bio *bounce_clone_bio(struct bio *bio_src)142{143 struct bvec_iter iter;144 struct bio_vec bv;145 struct bio *bio;146 147 /*148 * Pre immutable biovecs, __bio_clone() used to just do a memcpy from149 * bio_src->bi_io_vec to bio->bi_io_vec.150 *151 * We can't do that anymore, because:152 *153 * - The point of cloning the biovec is to produce a bio with a biovec154 * the caller can modify: bi_idx and bi_bvec_done should be 0.155 *156 * - The original bio could've had more than BIO_MAX_VECS biovecs; if157 * we tried to clone the whole thing bio_alloc_bioset() would fail.158 * But the clone should succeed as long as the number of biovecs we159 * actually need to allocate is fewer than BIO_MAX_VECS.160 *161 * - Lastly, bi_vcnt should not be looked at or relied upon by code162 * that does not own the bio - reason being drivers don't use it for163 * iterating over the biovec anymore, so expecting it to be kept up164 * to date (i.e. for clones that share the parent biovec) is just165 * asking for trouble and would force extra work.166 */167 bio = bio_alloc_bioset(bio_src->bi_bdev, bio_segments(bio_src),168 bio_src->bi_opf, GFP_NOIO, &bounce_bio_set);169 if (bio_flagged(bio_src, BIO_REMAPPED))170 bio_set_flag(bio, BIO_REMAPPED);171 bio->bi_ioprio = bio_src->bi_ioprio;172 bio->bi_write_hint = bio_src->bi_write_hint;173 bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;174 bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;175 176 switch (bio_op(bio)) {177 case REQ_OP_DISCARD:178 case REQ_OP_SECURE_ERASE:179 case REQ_OP_WRITE_ZEROES:180 break;181 default:182 bio_for_each_segment(bv, bio_src, iter)183 bio->bi_io_vec[bio->bi_vcnt++] = bv;184 break;185 }186 187 if (bio_crypt_clone(bio, bio_src, GFP_NOIO) < 0)188 goto err_put;189 190 if (bio_integrity(bio_src) &&191 bio_integrity_clone(bio, bio_src, GFP_NOIO) < 0)192 goto err_put;193 194 bio_clone_blkg_association(bio, bio_src);195 196 return bio;197 198err_put:199 bio_put(bio);200 return NULL;201}202 203struct bio *__blk_queue_bounce(struct bio *bio_orig, struct request_queue *q)204{205 struct bio *bio;206 int rw = bio_data_dir(bio_orig);207 struct bio_vec *to, from;208 struct bvec_iter iter;209 unsigned i = 0, bytes = 0;210 bool bounce = false;211 int sectors;212 213 bio_for_each_segment(from, bio_orig, iter) {214 if (i++ < BIO_MAX_VECS)215 bytes += from.bv_len;216 if (PageHighMem(from.bv_page))217 bounce = true;218 }219 if (!bounce)220 return bio_orig;221 222 /*223 * Individual bvecs might not be logical block aligned. Round down224 * the split size so that each bio is properly block size aligned,225 * even if we do not use the full hardware limits.226 */227 sectors = ALIGN_DOWN(bytes, queue_logical_block_size(q)) >>228 SECTOR_SHIFT;229 if (sectors < bio_sectors(bio_orig)) {230 bio = bio_split(bio_orig, sectors, GFP_NOIO, &bounce_bio_split);231 bio_chain(bio, bio_orig);232 submit_bio_noacct(bio_orig);233 bio_orig = bio;234 }235 bio = bounce_clone_bio(bio_orig);236 237 /*238 * Bvec table can't be updated by bio_for_each_segment_all(),239 * so retrieve bvec from the table directly. This way is safe240 * because the 'bio' is single-page bvec.241 */242 for (i = 0, to = bio->bi_io_vec; i < bio->bi_vcnt; to++, i++) {243 struct page *bounce_page;244 245 if (!PageHighMem(to->bv_page))246 continue;247 248 bounce_page = mempool_alloc(&page_pool, GFP_NOIO);249 inc_zone_page_state(bounce_page, NR_BOUNCE);250 251 if (rw == WRITE) {252 flush_dcache_page(to->bv_page);253 memcpy_from_bvec(page_address(bounce_page), to);254 }255 to->bv_page = bounce_page;256 }257 258 trace_block_bio_bounce(bio_orig);259 260 bio->bi_flags |= (1 << BIO_BOUNCED);261 262 if (rw == READ)263 bio->bi_end_io = bounce_end_io_read;264 else265 bio->bi_end_io = bounce_end_io_write;266 267 bio->bi_private = bio_orig;268 return bio;269}270