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/* bounce buffer handling for block devices

 *

 * - Split from highmem.c

 */

#include <linux/mm.h>

#include <linux/module.h>

#include <linux/swap.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/blktrace_api.h>

#include <asm/tlbflush.h>

#define POOL_SIZE       64

#define ISA_POOL_SIZE   16

static mempool_t *page_pool, *isa_page_pool;

#ifdef CONFIG_HIGHMEM

static __init int init_emergency_pool(void)

{

        struct sysinfo i;

        si_meminfo(&i);

        si_swapinfo(&i);

        if (!i.totalhigh)

                return 0;

        page_pool = mempool_create_page_pool(POOL_SIZE, 0);

        BUG_ON(!page_pool);

        printk("highmem bounce pool size: %d pages\n", POOL_SIZE);

        return 0;

}

__initcall(init_emergency_pool);

/*

 * 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, KM_BOUNCE_READ);

        memcpy(vto + to->bv_offset, vfrom, to->bv_len);

        kunmap_atomic(vto, KM_BOUNCE_READ);

        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;

        int i;

        __bio_for_each_segment(tovec, to, i, 0) {

                fromvec = from->bi_io_vec + i;

                /*

                 * not bounced

                 */

                if (tovec->bv_page == fromvec->bv_page)

                        continue;

                /*

                 * 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;

                flush_dcache_page(tovec->bv_page);

                bounce_copy_vec(tovec, vfrom);

        }

}

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(bvec, bio, i, 0) {

                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);

}

static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,

                               mempool_t *pool)

{

        struct page *page;

        struct bio *bio = NULL;

        int i, rw = bio_data_dir(*bio_orig);

        struct bio_vec *to, *from;

        bio_for_each_segment(from, *bio_orig, i) {

                page = from->bv_page;

                /*

                 * is destination page below bounce pfn?

                 */

                if (page_to_pfn(page) <= q->bounce_pfn)

                        continue;

                /*

                 * irk, bounce it

                 */

                if (!bio)

                        bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);

                to = bio->bi_io_vec + i;

                to->bv_page = mempool_alloc(pool, q->bounce_gfp);

                to->bv_len = from->bv_len;

                to->bv_offset = from->bv_offset;

                inc_zone_page_state(to->bv_page, NR_BOUNCE);

                if (rw == WRITE) {

                        char *vto, *vfrom;

                        flush_dcache_page(from->bv_page);

                        vto = page_address(to->bv_page) + to->bv_offset;

                        vfrom = kmap(from->bv_page) + from->bv_offset;

                        memcpy(vto, vfrom, to->bv_len);

                        kunmap(from->bv_page);

                }

        }

        /*

         * no pages bounced

         */

        if (!bio)

                return;

        blk_add_trace_bio(q, *bio_orig, BLK_TA_BOUNCE);

        /*

         * at least one page was bounced, fill in possible non-highmem

         * pages

         */

        __bio_for_each_segment(from, *bio_orig, i, 0) {

                to = bio_iovec_idx(bio, i);

                if (!to->bv_page) {

                        to->bv_page = from->bv_page;

                        to->bv_len = from->bv_len;

                        to->bv_offset = from->bv_offset;

                }

        }

        bio->bi_bdev = (*bio_orig)->bi_bdev;

        bio->bi_flags |= (1 << BIO_BOUNCED);

        bio->bi_sector = (*bio_orig)->bi_sector;

        bio->bi_rw = (*bio_orig)->bi_rw;

        bio->bi_vcnt = (*bio_orig)->bi_vcnt;

        bio->bi_idx = (*bio_orig)->bi_idx;

        bio->bi_size = (*bio_orig)->bi_size;

        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_empty_barrier(*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->bounce_pfn >= blk_max_pfn)

                        return;

                pool = page_pool;

        } else {

                BUG_ON(!isa_page_pool);

                pool = isa_page_pool;

        }

        /*

         * slow path

         */

        __blk_queue_bounce(q, bio_orig, pool);

}

EXPORT_SYMBOL(blk_queue_bounce);