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Subject[PATCH 04/19] BLOCK: Separate the bounce buffering code from the highmem code [try #6]
Date
From: David Howells <dhowells@redhat.com>

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>
---
mm/Makefile | 4 +
mm/bounce.c | 302 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
mm/highmem.c | 281 ------------------------------------------------------
3 files changed, 305 insertions(+), 282 deletions(-)
diff --git a/mm/Makefile b/mm/Makefile
index 9dd824c..63637f0 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -12,6 +12,9 @@ obj-y := bootmem.o filemap.o mempool.o
readahead.o swap.o truncate.o vmscan.o \
prio_tree.o util.o mmzone.o vmstat.o $(mmu-y)

+ifeq ($(CONFIG_MMU),y)
+obj-y += bounce.o
+endif
obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o thrash.o
obj-$(CONFIG_HUGETLBFS) += hugetlb.o
obj-$(CONFIG_NUMA) += mempolicy.o
@@ -23,4 +26,3 @@ obj-$(CONFIG_SLAB) += slab.o
obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
obj-$(CONFIG_FS_XIP) += filemap_xip.o
obj-$(CONFIG_MIGRATION) += migrate.o
-
diff --git a/mm/bounce.c b/mm/bounce.c
new file mode 100644
index 0000000..e4b62d2
--- /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);
diff --git a/mm/highmem.c b/mm/highmem.c
index 9b2a540..1ac20d6 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -29,13 +29,6 @@ #include <linux/highmem.h>
#include <linux/blktrace_api.h>
#include <asm/tlbflush.h>

-static mempool_t *page_pool, *isa_page_pool;
-
-static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
-{
- return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
-}
-
/*
* Virtual_count is not a pure "count".
* 0 means that it is not mapped, and has not been mapped
@@ -204,282 +197,8 @@ void fastcall kunmap_high(struct page *p
}

EXPORT_SYMBOL(kunmap_high);
-
-#define POOL_SIZE 64
-
-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

-#define ISA_POOL_SIZE 16
-
-/*
- * 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);
-
#if defined(HASHED_PAGE_VIRTUAL)

#define PA_HASH_ORDER 7
-
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