block: move mm/bounce.c to block/

Continue moving some of the block files that are scattered around.
bounce.c contains only code for bouncing the contents of a bio.
It's block proper code, not mm code.

Suggested-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

2 files changed, 288 insertions, 0 deletions

diff --git a/block/Makefile b/block/Makefile
index b4c4d3b99a2d..a2ce6ac935ec 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_BLOCK) := bio.o elevator.o blk-core.o blk-tag.o blk-sysfs.o \
                         genhd.o scsi_ioctl.o partition-generic.o ioprio.o \
                         partitions/
 
+obj-$(CONFIG_BOUNCE)    += bounce.o
 obj-$(CONFIG_BLK_DEV_BSG)       += bsg.o
 obj-$(CONFIG_BLK_DEV_BSGLIB)    += bsg-lib.o
 obj-$(CONFIG_BLK_CGROUP)        += blk-cgroup.o
diff --git a/block/bounce.c b/block/bounce.c
new file mode 100644
index 000000000000..523918b8c6dc
--- /dev/null
+++ b/block/bounce.c
@@ -0,0 +1,287 @@
+/* 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);