// SPDX-License-Identifier: GPL-2.0 /* bounce buffer handling for block devices * * - Split from highmem.c */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #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/backing-dev.h> #include <linux/init.h> #include <linux/hash.h> #include <linux/highmem.h> #include <linux/memblock.h> #include <linux/printk.h> #include <asm/tlbflush.h> #include <trace/events/block.h> #include "blk.h" #define POOL_SIZE 64 #define ISA_POOL_SIZE 16 static struct bio_set bounce_bio_set, bounce_bio_split; static mempool_t page_pool, isa_page_pool; static void init_bounce_bioset(void) { static bool bounce_bs_setup; int ret; if (bounce_bs_setup) return; ret = bioset_init(&bounce_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); BUG_ON(ret); if (bioset_integrity_create(&bounce_bio_set, BIO_POOL_SIZE)) BUG_ON(1); ret = bioset_init(&bounce_bio_split, BIO_POOL_SIZE, 0, 0); BUG_ON(ret); bounce_bs_setup = true; } #if defined(CONFIG_HIGHMEM) static __init int init_emergency_pool(void) { int ret; #if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG) if (max_pfn <= max_low_pfn) return 0; #endif ret = mempool_init_page_pool(&page_pool, POOL_SIZE, 0); BUG_ON(ret); pr_info("pool size: %d pages\n", POOL_SIZE); init_bounce_bioset(); 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 char *vto; vto = kmap_atomic(to->bv_page); memcpy(vto + to->bv_offset, vfrom, to->bv_len); kunmap_atomic(vto); } #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); } static DEFINE_MUTEX(isa_mutex); /* * 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) { int ret; mutex_lock(&isa_mutex); if (mempool_initialized(&isa_page_pool)) { mutex_unlock(&isa_mutex); return 0; } ret = mempool_init(&isa_page_pool, ISA_POOL_SIZE, mempool_alloc_pages_isa, mempool_free_pages, (void *) 0); BUG_ON(ret); pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE); init_bounce_bioset(); mutex_unlock(&isa_mutex); 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; struct bvec_iter iter; /* * The bio of @from is created by bounce, so we can iterate * its bvec from start to end, but the @from->bi_iter can't be * trusted because it might be changed by splitting. */ struct bvec_iter from_iter = BVEC_ITER_ALL_INIT; bio_for_each_segment(tovec, to, iter) { fromvec = bio_iter_iovec(from, from_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); } bio_advance_iter(from, &from_iter, tovec.bv_len); } } static void bounce_end_io(struct bio *bio, mempool_t *pool) { struct bio *bio_orig = bio->bi_private; struct bio_vec *bvec, orig_vec; struct bvec_iter orig_iter = bio_orig->bi_iter; struct bvec_iter_all iter_all; /* * free up bounce indirect pages used */ bio_for_each_segment_all(bvec, bio, iter_all) { orig_vec = bio_iter_iovec(bio_orig, orig_iter); if (bvec->bv_page != orig_vec.bv_page) { dec_zone_page_state(bvec->bv_page, NR_BOUNCE); mempool_free(bvec->bv_page, pool); } bio_advance_iter(bio_orig, &orig_iter, orig_vec.bv_len); } bio_orig->bi_status = bio->bi_status; bio_endio(bio_orig); bio_put(bio); } static void bounce_end_io_write(struct bio *bio) { bounce_end_io(bio, &page_pool); } static void bounce_end_io_write_isa(struct bio *bio) { bounce_end_io(bio, &isa_page_pool); } static void __bounce_end_io_read(struct bio *bio, mempool_t *pool) { struct bio *bio_orig = bio->bi_private; if (!bio->bi_status) copy_to_high_bio_irq(bio_orig, bio); bounce_end_io(bio, pool); } static void bounce_end_io_read(struct bio *bio) { __bounce_end_io_read(bio, &page_pool); } static void bounce_end_io_read_isa(struct bio *bio) { __bounce_end_io_read(bio, &isa_page_pool); } static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask, struct bio_set *bs) { struct bvec_iter iter; struct bio_vec bv; struct bio *bio; /* * Pre immutable biovecs, __bio_clone() used to just do a memcpy from * bio_src->bi_io_vec to bio->bi_io_vec. * * We can't do that anymore, because: * * - The point of cloning the biovec is to produce a bio with a biovec * the caller can modify: bi_idx and bi_bvec_done should be 0. * * - The original bio could've had more than BIO_MAX_PAGES biovecs; if * we tried to clone the whole thing bio_alloc_bioset() would fail. * But the clone should succeed as long as the number of biovecs we * actually need to allocate is fewer than BIO_MAX_PAGES. * * - Lastly, bi_vcnt should not be looked at or relied upon by code * that does not own the bio - reason being drivers don't use it for * iterating over the biovec anymore, so expecting it to be kept up * to date (i.e. for clones that share the parent biovec) is just * asking for trouble and would force extra work on * __bio_clone_fast() anyways. */ bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs); if (!bio) return NULL; bio->bi_disk = bio_src->bi_disk; bio->bi_opf = bio_src->bi_opf; bio->bi_ioprio = bio_src->bi_ioprio; bio->bi_write_hint = bio_src->bi_write_hint; bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector; bio->bi_iter.bi_size = bio_src->bi_iter.bi_size; switch (bio_op(bio)) { case REQ_OP_DISCARD: case REQ_OP_SECURE_ERASE: case REQ_OP_WRITE_ZEROES: break; case REQ_OP_WRITE_SAME: bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0]; break; default: bio_for_each_segment(bv, bio_src, iter) bio->bi_io_vec[bio->bi_vcnt++] = bv; break; } if (bio_integrity(bio_src)) { int ret; ret = bio_integrity_clone(bio, bio_src, gfp_mask); if (ret < 0) { bio_put(bio); return NULL; } } bio_clone_blkg_association(bio, bio_src); blkcg_bio_issue_init(bio); return bio; } static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, mempool_t *pool) { struct bio *bio; int rw = bio_data_dir(*bio_orig); struct bio_vec *to, from; struct bvec_iter iter; unsigned i = 0; bool bounce = false; int sectors = 0; bool passthrough = bio_is_passthrough(*bio_orig); bio_for_each_segment(from, *bio_orig, iter) { if (i++ < BIO_MAX_PAGES) sectors += from.bv_len >> 9; if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn) bounce = true; } if (!bounce) return; if (!passthrough && sectors < bio_sectors(*bio_orig)) { bio = bio_split(*bio_orig, sectors, GFP_NOIO, &bounce_bio_split); bio_chain(bio, *bio_orig); generic_make_request(*bio_orig); *bio_orig = bio; } bio = bounce_clone_bio(*bio_orig, GFP_NOIO, passthrough ? NULL : &bounce_bio_set); /* * Bvec table can't be updated by bio_for_each_segment_all(), * so retrieve bvec from the table directly. This way is safe * because the 'bio' is single-page bvec. */ for (i = 0, to = bio->bi_io_vec; i < bio->bi_vcnt; to++, i++) { struct page *page = to->bv_page; if (page_to_pfn(page) <= q->limits.bounce_pfn) continue; to->bv_page = mempool_alloc(pool, q->bounce_gfp); inc_zone_page_state(to->bv_page, NR_BOUNCE); 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) { mempool_t *pool; /* * Data-less bio, nothing to bounce */ if (!bio_has_data(*bio_orig)) return; /* * 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 (q->limits.bounce_pfn >= blk_max_pfn) return; pool = &page_pool; } else { BUG_ON(!mempool_initialized(&isa_page_pool)); pool = &isa_page_pool; } /* * slow path */ __blk_queue_bounce(q, bio_orig, pool); }