// 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/blk-cgroup.h> #include <linux/backing-dev.h> #include <linux/init.h> #include <linux/hash.h> #include <linux/highmem.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; 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; } static __init int init_emergency_pool(void) { int ret; #ifndef 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); /* * 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) { 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 */ memcpy_to_bvec(&tovec, page_address(fromvec.bv_page) + tovec.bv_offset); } bio_advance_iter(from, &from_iter, tovec.bv_len); } } static void bounce_end_io(struct bio *bio) { 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, &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); } static void bounce_end_io_read(struct bio *bio) { struct bio *bio_orig = bio->bi_private; if (!bio->bi_status) copy_to_high_bio_irq(bio_orig, bio); bounce_end_io(bio); } static struct bio *bounce_clone_bio(struct bio *bio_src) { 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_VECS 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_VECS. * * - 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_NOIO, bio_segments(bio_src), &bounce_bio_set); bio->bi_bdev = bio_src->bi_bdev; if (bio_flagged(bio_src, BIO_REMAPPED)) bio_set_flag(bio, BIO_REMAPPED); 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_crypt_clone(bio, bio_src, GFP_NOIO) < 0) goto err_put; if (bio_integrity(bio_src) && bio_integrity_clone(bio, bio_src, GFP_NOIO) < 0) goto err_put; bio_clone_blkg_association(bio, bio_src); blkcg_bio_issue_init(bio); return bio; err_put: bio_put(bio); return NULL; } void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) { 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; bio_for_each_segment(from, *bio_orig, iter) { if (i++ < BIO_MAX_VECS) sectors += from.bv_len >> 9; if (PageHighMem(from.bv_page)) bounce = true; } if (!bounce) return; if (sectors < bio_sectors(*bio_orig)) { bio = bio_split(*bio_orig, sectors, GFP_NOIO, &bounce_bio_split); bio_chain(bio, *bio_orig); submit_bio_noacct(*bio_orig); *bio_orig = bio; } bio = bounce_clone_bio(*bio_orig); /* * 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 *bounce_page; if (!PageHighMem(to->bv_page)) continue; bounce_page = mempool_alloc(&page_pool, GFP_NOIO); inc_zone_page_state(bounce_page, NR_BOUNCE); if (rw == WRITE) { flush_dcache_page(to->bv_page); memcpy_from_bvec(page_address(bounce_page), to); } to->bv_page = bounce_page; } trace_block_bio_bounce(*bio_orig); bio->bi_flags |= (1 << BIO_BOUNCED); if (rw == READ) bio->bi_end_io = bounce_end_io_read; else bio->bi_end_io = bounce_end_io_write; bio->bi_private = *bio_orig; *bio_orig = bio; }