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![Ming Lei](/assets/img/avatar_default.png)
Block bounce needs to allocate new page for doing IO, and the new page has to be updated to bvec table. Commit6dc4f100c
switches __blk_queue_bounce() to use the new bio_for_each_segment_all() interface. Unfortunately the new bio_for_each_segment_all() can't be used to update bvec table. This patch fixes this issue by retrieving bvec from the table directly, then the new allocated page can be updated to the bio. This way is safe because the cloned bio is single page bvec. Fixes:6dc4f100c
("block: allow bio_for_each_segment_all() to iterate over multi-page bvec") Cc: Christoph Hellwig <hch@lst.de> Cc: Omar Sandoval <osandov@fb.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
389 lines
9.4 KiB
C
389 lines
9.4 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/memblock.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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#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, isa_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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#if defined(CONFIG_HIGHMEM)
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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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#if defined(CONFIG_HIGHMEM) && !defined(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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#endif
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#ifdef CONFIG_HIGHMEM
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/*
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* highmem version, map in to vec
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*/
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static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
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{
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unsigned char *vto;
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vto = kmap_atomic(to->bv_page);
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memcpy(vto + to->bv_offset, vfrom, to->bv_len);
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kunmap_atomic(vto);
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}
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#else /* CONFIG_HIGHMEM */
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#define bounce_copy_vec(to, vfrom) \
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memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
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#endif /* CONFIG_HIGHMEM */
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/*
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* allocate pages in the DMA region for the ISA pool
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*/
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static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
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{
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return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
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}
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static DEFINE_MUTEX(isa_mutex);
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/*
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* gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
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* as the max address, so check if the pool has already been created.
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*/
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int init_emergency_isa_pool(void)
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{
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int ret;
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mutex_lock(&isa_mutex);
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if (mempool_initialized(&isa_page_pool)) {
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mutex_unlock(&isa_mutex);
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return 0;
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}
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ret = mempool_init(&isa_page_pool, ISA_POOL_SIZE, mempool_alloc_pages_isa,
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mempool_free_pages, (void *) 0);
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BUG_ON(ret);
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pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE);
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init_bounce_bioset();
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mutex_unlock(&isa_mutex);
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return 0;
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}
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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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unsigned char *vfrom;
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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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vfrom = page_address(fromvec.bv_page) +
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tovec.bv_offset;
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bounce_copy_vec(&tovec, vfrom);
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flush_dcache_page(tovec.bv_page);
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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, mempool_t *pool)
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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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int i;
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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, i, 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, 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, &page_pool);
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}
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static void bounce_end_io_write_isa(struct bio *bio)
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{
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bounce_end_io(bio, &isa_page_pool);
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}
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static void __bounce_end_io_read(struct bio *bio, mempool_t *pool)
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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, pool);
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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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__bounce_end_io_read(bio, &page_pool);
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}
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static void bounce_end_io_read_isa(struct bio *bio)
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{
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__bounce_end_io_read(bio, &isa_page_pool);
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}
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static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,
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struct bio_set *bs)
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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_PAGES 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_PAGES.
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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 on
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* __bio_clone_fast() anyways.
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*/
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bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
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if (!bio)
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return NULL;
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bio->bi_disk = bio_src->bi_disk;
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bio->bi_opf = bio_src->bi_opf;
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bio->bi_ioprio = bio_src->bi_ioprio;
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bio->bi_write_hint = bio_src->bi_write_hint;
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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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case REQ_OP_WRITE_SAME:
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bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
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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_integrity(bio_src)) {
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int ret;
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ret = bio_integrity_clone(bio, bio_src, gfp_mask);
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if (ret < 0) {
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bio_put(bio);
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return NULL;
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}
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}
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bio_clone_blkg_association(bio, bio_src);
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blkcg_bio_issue_init(bio);
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return bio;
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}
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static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
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mempool_t *pool)
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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;
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bool bounce = false;
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int sectors = 0;
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bool passthrough = bio_is_passthrough(*bio_orig);
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bio_for_each_segment(from, *bio_orig, iter) {
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if (i++ < BIO_MAX_PAGES)
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sectors += from.bv_len >> 9;
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if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn)
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bounce = true;
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}
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if (!bounce)
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return;
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if (!passthrough && 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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generic_make_request(*bio_orig);
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*bio_orig = bio;
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}
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bio = bounce_clone_bio(*bio_orig, GFP_NOIO, passthrough ? NULL :
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&bounce_bio_set);
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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 *page = to->bv_page;
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if (page_to_pfn(page) <= q->limits.bounce_pfn)
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continue;
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to->bv_page = mempool_alloc(pool, q->bounce_gfp);
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inc_zone_page_state(to->bv_page, NR_BOUNCE);
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if (rw == WRITE) {
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char *vto, *vfrom;
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flush_dcache_page(page);
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vto = page_address(to->bv_page) + to->bv_offset;
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vfrom = kmap_atomic(page) + to->bv_offset;
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memcpy(vto, vfrom, to->bv_len);
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kunmap_atomic(vfrom);
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}
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}
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trace_block_bio_bounce(q, *bio_orig);
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bio->bi_flags |= (1 << BIO_BOUNCED);
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if (pool == &page_pool) {
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bio->bi_end_io = bounce_end_io_write;
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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_isa;
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if (rw == READ)
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bio->bi_end_io = bounce_end_io_read_isa;
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}
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bio->bi_private = *bio_orig;
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*bio_orig = bio;
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}
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void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
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{
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mempool_t *pool;
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/*
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* Data-less bio, nothing to bounce
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*/
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if (!bio_has_data(*bio_orig))
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return;
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/*
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* for non-isa bounce case, just check if the bounce pfn is equal
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* to or bigger than the highest pfn in the system -- in that case,
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* don't waste time iterating over bio segments
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*/
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if (!(q->bounce_gfp & GFP_DMA)) {
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if (q->limits.bounce_pfn >= blk_max_pfn)
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return;
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pool = &page_pool;
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} else {
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BUG_ON(!mempool_initialized(&isa_page_pool));
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pool = &isa_page_pool;
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}
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/*
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* slow path
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*/
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__blk_queue_bounce(q, bio_orig, pool);
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}
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