/* bounce buffer handling for block devices * * - Split from highmem.c */ #include <linux/mm.h> #include <linux/export.h> #include <linux/swap.h> #include <linux/gfp.h> #include <linux/bio.h> #include <linux/pagemap.h> #include <linux/mempool.h> #include <linux/blkdev.h> #include <linux/init.h> #include <linux/hash.h> #include <linux/highmem.h> #include <linux/bootmem.h> #include <asm/tlbflush.h> #include <trace/events/block.h> #define POOL_SIZE 64 #define ISA_POOL_SIZE 16 static mempool_t *page_pool, *isa_page_pool; #if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL) static __init int init_emergency_pool(void) { #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG) if (max_pfn <= max_low_pfn) return 0; #endif page_pool = mempool_create_page_pool(POOL_SIZE, 0); BUG_ON(!page_pool); printk("bounce pool size: %d pages\n", POOL_SIZE); return 0; } __initcall(init_emergency_pool); #endif #ifdef CONFIG_HIGHMEM /* * highmem version, map in to vec */ static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) { unsigned long flags; unsigned char *vto; local_irq_save(flags); vto = kmap_atomic(to->bv_page); memcpy(vto + to->bv_offset, vfrom, to->bv_len); kunmap_atomic(vto); local_irq_restore(flags); } #else /* CONFIG_HIGHMEM */ #define bounce_copy_vec(to, vfrom) \ memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) #endif /* CONFIG_HIGHMEM */ /* * allocate pages in the DMA region for the ISA pool */ static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data) { return mempool_alloc_pages(gfp_mask | GFP_DMA, data); } /* * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA * as the max address, so check if the pool has already been created. */ int init_emergency_isa_pool(void) { if (isa_page_pool) return 0; isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa, mempool_free_pages, (void *) 0); BUG_ON(!isa_page_pool); printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE); return 0; } /* * Simple bounce buffer support for highmem pages. Depending on the * queue gfp mask set, *to may or may not be a highmem page. kmap it * always, it will do the Right Thing */ static void copy_to_high_bio_irq(struct bio *to, struct bio *from) { unsigned char *vfrom; struct bio_vec tovec, *fromvec = from->bi_io_vec; struct bvec_iter iter; bio_for_each_segment(tovec, to, iter) { if (tovec.bv_page != fromvec->bv_page) { /* * fromvec->bv_offset and fromvec->bv_len might have * been modified by the block layer, so use the original * copy, bounce_copy_vec already uses tovec->bv_len */ vfrom = page_address(fromvec->bv_page) + tovec.bv_offset; bounce_copy_vec(&tovec, vfrom); flush_dcache_page(tovec.bv_page); } fromvec++; } } static void bounce_end_io(struct bio *bio, mempool_t *pool, int err) { struct bio *bio_orig = bio->bi_private; struct bio_vec *bvec, *org_vec; int i; if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags)) set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags); /* * free up bounce indirect pages used */ bio_for_each_segment_all(bvec, bio, i) { org_vec = bio_orig->bi_io_vec + i; if (bvec->bv_page == org_vec->bv_page) continue; dec_zone_page_state(bvec->bv_page, NR_BOUNCE); mempool_free(bvec->bv_page, pool); } bio_endio(bio_orig, err); bio_put(bio); } static void bounce_end_io_write(struct bio *bio, int err) { bounce_end_io(bio, page_pool, err); } static void bounce_end_io_write_isa(struct bio *bio, int err) { bounce_end_io(bio, isa_page_pool, err); } static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err) { struct bio *bio_orig = bio->bi_private; if (test_bit(BIO_UPTODATE, &bio->bi_flags)) copy_to_high_bio_irq(bio_orig, bio); bounce_end_io(bio, pool, err); } static void bounce_end_io_read(struct bio *bio, int err) { __bounce_end_io_read(bio, page_pool, err); } static void bounce_end_io_read_isa(struct bio *bio, int err) { __bounce_end_io_read(bio, isa_page_pool, err); } #ifdef CONFIG_NEED_BOUNCE_POOL static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) { if (bio_data_dir(bio) != WRITE) return 0; if (!bdi_cap_stable_pages_required(&q->backing_dev_info)) return 0; return test_bit(BIO_SNAP_STABLE, &bio->bi_flags); } #else static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) { return 0; } #endif /* CONFIG_NEED_BOUNCE_POOL */ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, mempool_t *pool, int force) { struct bio *bio; int rw = bio_data_dir(*bio_orig); struct bio_vec *to, from; struct bvec_iter iter; unsigned i; if (force) goto bounce; bio_for_each_segment(from, *bio_orig, iter) if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q)) goto bounce; return; bounce: bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set); bio_for_each_segment_all(to, bio, i) { struct page *page = to->bv_page; if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force) continue; inc_zone_page_state(to->bv_page, NR_BOUNCE); to->bv_page = mempool_alloc(pool, q->bounce_gfp); if (rw == WRITE) { char *vto, *vfrom; flush_dcache_page(page); vto = page_address(to->bv_page) + to->bv_offset; vfrom = kmap_atomic(page) + to->bv_offset; memcpy(vto, vfrom, to->bv_len); kunmap_atomic(vfrom); } } trace_block_bio_bounce(q, *bio_orig); bio->bi_flags |= (1 << BIO_BOUNCED); if (pool == page_pool) { bio->bi_end_io = bounce_end_io_write; if (rw == READ) bio->bi_end_io = bounce_end_io_read; } else { bio->bi_end_io = bounce_end_io_write_isa; if (rw == READ) bio->bi_end_io = bounce_end_io_read_isa; } bio->bi_private = *bio_orig; *bio_orig = bio; } void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) { int must_bounce; mempool_t *pool; /* * Data-less bio, nothing to bounce */ if (!bio_has_data(*bio_orig)) return; must_bounce = must_snapshot_stable_pages(q, *bio_orig); /* * for non-isa bounce case, just check if the bounce pfn is equal * to or bigger than the highest pfn in the system -- in that case, * don't waste time iterating over bio segments */ if (!(q->bounce_gfp & GFP_DMA)) { if (queue_bounce_pfn(q) >= blk_max_pfn && !must_bounce) return; pool = page_pool; } else { BUG_ON(!isa_page_pool); pool = isa_page_pool; } /* * slow path */ __blk_queue_bounce(q, bio_orig, pool, must_bounce); } EXPORT_SYMBOL(blk_queue_bounce);