302 lines
6.5 KiB
C
302 lines
6.5 KiB
C
/* 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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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/swap.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/init.h>
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#include <linux/hash.h>
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#include <linux/highmem.h>
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#include <linux/blktrace_api.h>
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#include <trace/block.h>
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#include <asm/tlbflush.h>
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#define POOL_SIZE 64
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#define ISA_POOL_SIZE 16
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static mempool_t *page_pool, *isa_page_pool;
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DEFINE_TRACE(block_bio_bounce);
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#ifdef CONFIG_HIGHMEM
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static __init int init_emergency_pool(void)
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{
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struct sysinfo i;
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si_meminfo(&i);
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si_swapinfo(&i);
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if (!i.totalhigh)
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return 0;
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page_pool = mempool_create_page_pool(POOL_SIZE, 0);
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BUG_ON(!page_pool);
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printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
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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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* 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 long flags;
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unsigned char *vto;
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local_irq_save(flags);
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vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ);
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memcpy(vto + to->bv_offset, vfrom, to->bv_len);
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kunmap_atomic(vto, KM_BOUNCE_READ);
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local_irq_restore(flags);
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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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/*
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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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if (isa_page_pool)
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return 0;
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isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
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mempool_free_pages, (void *) 0);
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BUG_ON(!isa_page_pool);
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printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
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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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int i;
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__bio_for_each_segment(tovec, to, i, 0) {
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fromvec = from->bi_io_vec + i;
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/*
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* not bounced
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*/
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if (tovec->bv_page == fromvec->bv_page)
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continue;
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/*
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* fromvec->bv_offset and fromvec->bv_len might have been
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* modified by the block layer, so use the original copy,
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* bounce_copy_vec already uses tovec->bv_len
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*/
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vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
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flush_dcache_page(tovec->bv_page);
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bounce_copy_vec(tovec, vfrom);
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}
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}
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static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
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{
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struct bio *bio_orig = bio->bi_private;
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struct bio_vec *bvec, *org_vec;
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int i;
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if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
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set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
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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(bvec, bio, i, 0) {
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org_vec = bio_orig->bi_io_vec + i;
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if (bvec->bv_page == org_vec->bv_page)
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continue;
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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_endio(bio_orig, err);
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bio_put(bio);
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}
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static void bounce_end_io_write(struct bio *bio, int err)
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{
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bounce_end_io(bio, page_pool, err);
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}
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static void bounce_end_io_write_isa(struct bio *bio, int err)
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{
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bounce_end_io(bio, isa_page_pool, err);
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}
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static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
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{
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struct bio *bio_orig = bio->bi_private;
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if (test_bit(BIO_UPTODATE, &bio->bi_flags))
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copy_to_high_bio_irq(bio_orig, bio);
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bounce_end_io(bio, pool, err);
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}
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static void bounce_end_io_read(struct bio *bio, int err)
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{
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__bounce_end_io_read(bio, page_pool, err);
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}
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static void bounce_end_io_read_isa(struct bio *bio, int err)
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{
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__bounce_end_io_read(bio, isa_page_pool, err);
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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 page *page;
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struct bio *bio = NULL;
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int i, rw = bio_data_dir(*bio_orig);
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struct bio_vec *to, *from;
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bio_for_each_segment(from, *bio_orig, i) {
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page = from->bv_page;
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/*
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* is destination page below bounce pfn?
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*/
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if (page_to_pfn(page) <= q->bounce_pfn)
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continue;
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/*
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* irk, bounce it
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*/
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if (!bio) {
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unsigned int cnt = (*bio_orig)->bi_vcnt;
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bio = bio_alloc(GFP_NOIO, cnt);
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memset(bio->bi_io_vec, 0, cnt * sizeof(struct bio_vec));
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}
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to = bio->bi_io_vec + i;
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to->bv_page = mempool_alloc(pool, q->bounce_gfp);
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to->bv_len = from->bv_len;
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to->bv_offset = from->bv_offset;
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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(from->bv_page);
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vto = page_address(to->bv_page) + to->bv_offset;
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vfrom = kmap(from->bv_page) + from->bv_offset;
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memcpy(vto, vfrom, to->bv_len);
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kunmap(from->bv_page);
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}
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}
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/*
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* no pages bounced
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*/
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if (!bio)
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return;
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trace_block_bio_bounce(q, *bio_orig);
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/*
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* at least one page was bounced, fill in possible non-highmem
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* pages
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*/
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__bio_for_each_segment(from, *bio_orig, i, 0) {
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to = bio_iovec_idx(bio, i);
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if (!to->bv_page) {
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to->bv_page = from->bv_page;
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to->bv_len = from->bv_len;
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to->bv_offset = from->bv_offset;
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}
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}
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bio->bi_bdev = (*bio_orig)->bi_bdev;
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bio->bi_flags |= (1 << BIO_BOUNCED);
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bio->bi_sector = (*bio_orig)->bi_sector;
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bio->bi_rw = (*bio_orig)->bi_rw;
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bio->bi_vcnt = (*bio_orig)->bi_vcnt;
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bio->bi_idx = (*bio_orig)->bi_idx;
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bio->bi_size = (*bio_orig)->bi_size;
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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->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(!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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EXPORT_SYMBOL(blk_queue_bounce);
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