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The double indirect bio leads to somewhat suboptimal code generation. Instead return the (original or split) bio, and make sure the request_queue arguments to the lower level helpers is passed after the bio to avoid constant reshuffling of the argument passing registers. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20220727162300.3089193-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
269 lines
6.8 KiB
C
269 lines
6.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* bounce buffer handling for block devices
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*
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* - Split from highmem.c
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/mm.h>
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#include <linux/export.h>
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#include <linux/swap.h>
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#include <linux/gfp.h>
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#include <linux/bio.h>
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#include <linux/pagemap.h>
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#include <linux/mempool.h>
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#include <linux/blkdev.h>
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#include <linux/backing-dev.h>
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#include <linux/init.h>
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#include <linux/hash.h>
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#include <linux/highmem.h>
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#include <linux/printk.h>
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#include <asm/tlbflush.h>
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#include <trace/events/block.h>
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#include "blk.h"
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#include "blk-cgroup.h"
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#define POOL_SIZE 64
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#define ISA_POOL_SIZE 16
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static struct bio_set bounce_bio_set, bounce_bio_split;
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static mempool_t page_pool;
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static void init_bounce_bioset(void)
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{
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static bool bounce_bs_setup;
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int ret;
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if (bounce_bs_setup)
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return;
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ret = bioset_init(&bounce_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
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BUG_ON(ret);
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if (bioset_integrity_create(&bounce_bio_set, BIO_POOL_SIZE))
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BUG_ON(1);
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ret = bioset_init(&bounce_bio_split, BIO_POOL_SIZE, 0, 0);
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BUG_ON(ret);
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bounce_bs_setup = true;
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}
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static __init int init_emergency_pool(void)
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{
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int ret;
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#ifndef CONFIG_MEMORY_HOTPLUG
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if (max_pfn <= max_low_pfn)
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return 0;
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#endif
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ret = mempool_init_page_pool(&page_pool, POOL_SIZE, 0);
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BUG_ON(ret);
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pr_info("pool size: %d pages\n", POOL_SIZE);
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init_bounce_bioset();
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return 0;
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}
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__initcall(init_emergency_pool);
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/*
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* Simple bounce buffer support for highmem pages. Depending on the
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* queue gfp mask set, *to may or may not be a highmem page. kmap it
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* always, it will do the Right Thing
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*/
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static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
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{
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struct bio_vec tovec, fromvec;
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struct bvec_iter iter;
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/*
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* The bio of @from is created by bounce, so we can iterate
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* its bvec from start to end, but the @from->bi_iter can't be
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* trusted because it might be changed by splitting.
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*/
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struct bvec_iter from_iter = BVEC_ITER_ALL_INIT;
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bio_for_each_segment(tovec, to, iter) {
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fromvec = bio_iter_iovec(from, from_iter);
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if (tovec.bv_page != fromvec.bv_page) {
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/*
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* fromvec->bv_offset and fromvec->bv_len might have
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* been modified by the block layer, so use the original
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* copy, bounce_copy_vec already uses tovec->bv_len
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*/
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memcpy_to_bvec(&tovec, page_address(fromvec.bv_page) +
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tovec.bv_offset);
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}
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bio_advance_iter(from, &from_iter, tovec.bv_len);
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}
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}
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static void bounce_end_io(struct bio *bio)
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{
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struct bio *bio_orig = bio->bi_private;
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struct bio_vec *bvec, orig_vec;
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struct bvec_iter orig_iter = bio_orig->bi_iter;
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struct bvec_iter_all iter_all;
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/*
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* free up bounce indirect pages used
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*/
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bio_for_each_segment_all(bvec, bio, iter_all) {
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orig_vec = bio_iter_iovec(bio_orig, orig_iter);
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if (bvec->bv_page != orig_vec.bv_page) {
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dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
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mempool_free(bvec->bv_page, &page_pool);
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}
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bio_advance_iter(bio_orig, &orig_iter, orig_vec.bv_len);
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}
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bio_orig->bi_status = bio->bi_status;
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bio_endio(bio_orig);
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bio_put(bio);
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}
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static void bounce_end_io_write(struct bio *bio)
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{
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bounce_end_io(bio);
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}
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static void bounce_end_io_read(struct bio *bio)
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{
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struct bio *bio_orig = bio->bi_private;
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if (!bio->bi_status)
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copy_to_high_bio_irq(bio_orig, bio);
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bounce_end_io(bio);
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}
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static struct bio *bounce_clone_bio(struct bio *bio_src)
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{
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struct bvec_iter iter;
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struct bio_vec bv;
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struct bio *bio;
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/*
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* Pre immutable biovecs, __bio_clone() used to just do a memcpy from
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* bio_src->bi_io_vec to bio->bi_io_vec.
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*
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* We can't do that anymore, because:
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*
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* - The point of cloning the biovec is to produce a bio with a biovec
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* the caller can modify: bi_idx and bi_bvec_done should be 0.
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*
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* - The original bio could've had more than BIO_MAX_VECS biovecs; if
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* we tried to clone the whole thing bio_alloc_bioset() would fail.
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* But the clone should succeed as long as the number of biovecs we
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* actually need to allocate is fewer than BIO_MAX_VECS.
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*
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* - Lastly, bi_vcnt should not be looked at or relied upon by code
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* that does not own the bio - reason being drivers don't use it for
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* iterating over the biovec anymore, so expecting it to be kept up
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* to date (i.e. for clones that share the parent biovec) is just
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* asking for trouble and would force extra work.
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*/
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bio = bio_alloc_bioset(bio_src->bi_bdev, bio_segments(bio_src),
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bio_src->bi_opf, GFP_NOIO, &bounce_bio_set);
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if (bio_flagged(bio_src, BIO_REMAPPED))
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bio_set_flag(bio, BIO_REMAPPED);
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bio->bi_ioprio = bio_src->bi_ioprio;
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bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;
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bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;
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switch (bio_op(bio)) {
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case REQ_OP_DISCARD:
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case REQ_OP_SECURE_ERASE:
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case REQ_OP_WRITE_ZEROES:
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break;
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default:
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bio_for_each_segment(bv, bio_src, iter)
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bio->bi_io_vec[bio->bi_vcnt++] = bv;
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break;
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}
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if (bio_crypt_clone(bio, bio_src, GFP_NOIO) < 0)
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goto err_put;
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if (bio_integrity(bio_src) &&
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bio_integrity_clone(bio, bio_src, GFP_NOIO) < 0)
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goto err_put;
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bio_clone_blkg_association(bio, bio_src);
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return bio;
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err_put:
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bio_put(bio);
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return NULL;
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}
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struct bio *__blk_queue_bounce(struct bio *bio_orig, struct request_queue *q)
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{
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struct bio *bio;
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int rw = bio_data_dir(bio_orig);
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struct bio_vec *to, from;
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struct bvec_iter iter;
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unsigned i = 0, bytes = 0;
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bool bounce = false;
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int sectors;
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bio_for_each_segment(from, bio_orig, iter) {
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if (i++ < BIO_MAX_VECS)
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bytes += from.bv_len;
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if (PageHighMem(from.bv_page))
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bounce = true;
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}
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if (!bounce)
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return bio_orig;
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/*
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* Individual bvecs might not be logical block aligned. Round down
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* the split size so that each bio is properly block size aligned,
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* even if we do not use the full hardware limits.
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*/
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sectors = ALIGN_DOWN(bytes, queue_logical_block_size(q)) >>
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SECTOR_SHIFT;
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if (sectors < bio_sectors(bio_orig)) {
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bio = bio_split(bio_orig, sectors, GFP_NOIO, &bounce_bio_split);
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bio_chain(bio, bio_orig);
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submit_bio_noacct(bio_orig);
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bio_orig = bio;
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}
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bio = bounce_clone_bio(bio_orig);
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/*
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* Bvec table can't be updated by bio_for_each_segment_all(),
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* so retrieve bvec from the table directly. This way is safe
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* because the 'bio' is single-page bvec.
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*/
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for (i = 0, to = bio->bi_io_vec; i < bio->bi_vcnt; to++, i++) {
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struct page *bounce_page;
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if (!PageHighMem(to->bv_page))
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continue;
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bounce_page = mempool_alloc(&page_pool, GFP_NOIO);
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inc_zone_page_state(bounce_page, NR_BOUNCE);
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if (rw == WRITE) {
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flush_dcache_page(to->bv_page);
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memcpy_from_bvec(page_address(bounce_page), to);
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}
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to->bv_page = bounce_page;
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}
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trace_block_bio_bounce(bio_orig);
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bio->bi_flags |= (1 << BIO_BOUNCED);
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if (rw == READ)
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bio->bi_end_io = bounce_end_io_read;
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else
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bio->bi_end_io = bounce_end_io_write;
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bio->bi_private = bio_orig;
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return bio;
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}
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