1 files changed, 382 insertions, 0 deletions
diff --git a/block/bounce.c b/block/bounce.c
new file mode 100644
index 000000000..abb50e7e5
--- /dev/null
+++ b/block/bounce.c
@@ -0,0 +1,382 @@
+// 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/bootmem.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;
+	int i;
+	struct bvec_iter orig_iter = bio_orig->bi_iter;
+
+	/*
+	 * free up bounce indirect pages used
+	 */
+	bio_for_each_segment_all(bvec, bio, i) {
+		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_blkcg_association(bio, bio_src);
+
+	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);
+
+	bio_for_each_segment_all(to, bio, 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);
+}