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-rw-r--r--block/bounce.c268
1 files changed, 268 insertions, 0 deletions
diff --git a/block/bounce.c b/block/bounce.c
new file mode 100644
index 0000000000..7cfcb242f9
--- /dev/null
+++ b/block/bounce.c
@@ -0,0 +1,268 @@
+// 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/printk.h>
+#include <asm/tlbflush.h>
+
+#include <trace/events/block.h>
+#include "blk.h"
+#include "blk-cgroup.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.
+ */
+ bio = bio_alloc_bioset(bio_src->bi_bdev, bio_segments(bio_src),
+ bio_src->bi_opf, GFP_NOIO, &bounce_bio_set);
+ if (bio_flagged(bio_src, BIO_REMAPPED))
+ bio_set_flag(bio, BIO_REMAPPED);
+ bio->bi_ioprio = bio_src->bi_ioprio;
+ 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;
+ 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);
+
+ return bio;
+
+err_put:
+ bio_put(bio);
+ return NULL;
+}
+
+struct bio *__blk_queue_bounce(struct bio *bio_orig, struct request_queue *q)
+{
+ struct bio *bio;
+ int rw = bio_data_dir(bio_orig);
+ struct bio_vec *to, from;
+ struct bvec_iter iter;
+ unsigned i = 0, bytes = 0;
+ bool bounce = false;
+ int sectors;
+
+ bio_for_each_segment(from, bio_orig, iter) {
+ if (i++ < BIO_MAX_VECS)
+ bytes += from.bv_len;
+ if (PageHighMem(from.bv_page))
+ bounce = true;
+ }
+ if (!bounce)
+ return bio_orig;
+
+ /*
+ * Individual bvecs might not be logical block aligned. Round down
+ * the split size so that each bio is properly block size aligned,
+ * even if we do not use the full hardware limits.
+ */
+ sectors = ALIGN_DOWN(bytes, queue_logical_block_size(q)) >>
+ SECTOR_SHIFT;
+ 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;
+ return bio;
+}