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authorDavid Howells <dhowells@redhat.com>2006-08-29 19:06:00 +0100
committerJens Axboe <axboe@nelson.home.kernel.dk>2006-09-30 20:32:11 +0200
commit831058dec3735665fe91bd0d37b6a8cf56b91abd (patch)
tree5ef7d38d9c43b24d5a31eb8f0e23c91e20e799e7 /mm/bounce.c
parentb398f6bff93a247d2a7099e92905374966e4558f (diff)
downloadlinux-831058dec3735665fe91bd0d37b6a8cf56b91abd.tar.gz
[PATCH] BLOCK: Separate the bounce buffering code from the highmem code [try #6]
Move the bounce buffer code from mm/highmem.c to mm/bounce.c so that it can be more easily disabled when the block layer is disabled. !!!NOTE!!! There may be a bug in this code: Should init_emergency_pool() be contingent on CONFIG_HIGHMEM? Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'mm/bounce.c')
-rw-r--r--mm/bounce.c302
1 files changed, 302 insertions, 0 deletions
diff --git a/mm/bounce.c b/mm/bounce.c
new file mode 100644
index 00000000000..e4b62d2a402
--- /dev/null
+++ b/mm/bounce.c
@@ -0,0 +1,302 @@
+/* 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, bio_orig->bi_size, err);
+ bio_put(bio);
+}
+
+static int bounce_end_io_write(struct bio *bio, unsigned int bytes_done, int err)
+{
+ if (bio->bi_size)
+ return 1;
+
+ bounce_end_io(bio, page_pool, err);
+ return 0;
+}
+
+static int bounce_end_io_write_isa(struct bio *bio, unsigned int bytes_done, int err)
+{
+ if (bio->bi_size)
+ return 1;
+
+ bounce_end_io(bio, isa_page_pool, err);
+ return 0;
+}
+
+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 int bounce_end_io_read(struct bio *bio, unsigned int bytes_done, int err)
+{
+ if (bio->bi_size)
+ return 1;
+
+ __bounce_end_io_read(bio, page_pool, err);
+ return 0;
+}
+
+static int bounce_end_io_read_isa(struct bio *bio, unsigned int bytes_done, int err)
+{
+ if (bio->bi_size)
+ return 1;
+
+ __bounce_end_io_read(bio, isa_page_pool, err);
+ return 0;
+}
+
+static void __blk_queue_bounce(request_queue_t *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;
+
+ /*
+ * 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(request_queue_t *q, struct bio **bio_orig)
+{
+ mempool_t *pool;
+
+ /*
+ * 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;
+ }
+
+ blk_add_trace_bio(q, *bio_orig, BLK_TA_BOUNCE);
+
+ /*
+ * slow path
+ */
+ __blk_queue_bounce(q, bio_orig, pool);
+}
+
+EXPORT_SYMBOL(blk_queue_bounce);