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268 lines
6.7 KiB
268 lines
6.7 KiB
// 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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#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 on |
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* __bio_clone_fast() anyways. |
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*/ |
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bio = bio_alloc_bioset(GFP_NOIO, bio_segments(bio_src), |
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&bounce_bio_set); |
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bio->bi_bdev = bio_src->bi_bdev; |
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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_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_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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blkcg_bio_issue_init(bio); |
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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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void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) |
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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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bio_for_each_segment(from, *bio_orig, iter) { |
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if (i++ < BIO_MAX_VECS) |
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sectors += from.bv_len >> 9; |
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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; |
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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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*bio_orig = bio; |
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}
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