On architectures where highmem isn't used, arguments to kmap/unmap are
simply thrown away without being evaluated.  This is fine until a
wrapper function is written.  Even though it got ignored in the end,
the arguments are evaulated.  As asm/highmem.h is not included by
linux/highmem.h when CONFIG_HIGHMEM is off, none of KM_* constants get
defined which results in error if those are evaluated.

This patch makes linux/highmem.h include asm/kmap_types.h regardless
of CONFIG_HIGHMEM.  To deal with the same problem, crypto subsystem
used to include asm/kmap_types.h directly.  This patch kills it.

Signed-off-by: Tejun Heo <htejun@gmail.com>

---

 crypto/internal.h       |    1 -
 include/linux/highmem.h |    1 +
 2 files changed, 1 insertions(+), 1 deletions(-)

4e0462fa09e87da901867f37b2c7311ef714c3e7
diff --git a/crypto/internal.h b/crypto/internal.h
index 959e602..4188672 100644
--- a/crypto/internal.h
+++ b/crypto/internal.h
@@ -21,7 +21,6 @@
 #include <linux/kernel.h>
 #include <linux/rwsem.h>
 #include <linux/slab.h>
-#include <asm/kmap_types.h>
 
 extern struct list_head crypto_alg_list;
 extern struct rw_semaphore crypto_alg_sem;
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 6bece92..c605f01 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -6,6 +6,7 @@
 #include <linux/mm.h>
 
 #include <asm/cacheflush.h>
+#include <asm/kmap_types.h>
 
 #ifdef CONFIG_HIGHMEM
 

When block requests are handled via DMA dma mapping functions take
care of cache coherency.  Unfortunately, cache coherencly was left
unhandled until now for block PIOs, resulting in data corruption
issues on architectures with aliasing caches.

All block PIO operations use kmap/unmap to access target memory area
and the mapping/unmapping points are the perfect places for cache
flushing.  kmap/unmap are to PIO'ing cpus what dma_map/unmap are to
DMAing devices.

This patch implements blk kmap helpers which additionally take
@direction argument and deal with cache coherency.

Signed-off-by: Tejun Heo <htejun@gmail.com>

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 02a585f..1040029 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -17,6 +17,10 @@
 
 #include <asm/scatterlist.h>
 
+/* for PIO kmap helpers */
+#include <linux/highmem.h>
+#include <linux/dma-mapping.h>
+
 struct request_queue;
 typedef struct request_queue request_queue_t;
 struct elevator_queue;
@@ -812,6 +816,40 @@ static inline void put_dev_sector(Sector
 	page_cache_release(p.v);
 }
 
+/*
+ * PIO kmap helpers.
+ *
+ * Block PIO requires cache flushes on architectures with aliasing
+ * caches.  If a driver wants to perform PIO on a user-mappable page
+ * (page cache page), it MUST use one of the following kmap/unmap
+ * helpers unless it handles cache coherency itself.
+ */
+static inline void * blk_kmap_atomic(struct page *page, enum km_type type,
+				     enum dma_data_direction dir)
+{
+	return kmap_atomic(page, type);
+}
+
+static inline void blk_kunmap_atomic(void *addr, enum km_type type,
+				     enum dma_data_direction dir)
+{
+	if (dir == DMA_BIDIRECTIONAL || dir == DMA_FROM_DEVICE)
+		flush_dcache_page(kmap_atomic_to_page(addr));
+	kunmap_atomic(addr, type);
+}
+
+static inline void * blk_kmap(struct page *page, enum dma_data_direction dir)
+{
+	return kmap(page);
+}
+
+static inline void blk_kunmap(struct page *page, enum dma_data_direction dir)
+{
+	if (dir == DMA_BIDIRECTIONAL || dir == DMA_FROM_DEVICE)
+		flush_dcache_page(page);
+	kunmap(page);
+}
+
 struct work_struct;
 int kblockd_schedule_work(struct work_struct *work);
 void kblockd_flush(void);
diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
index 62ebefd..24d5e56 100644
--- a/drivers/ide/ide-taskfile.c
+++ b/drivers/ide/ide-taskfile.c
@@ -260,6 +260,7 @@ static void ide_pio_sector(ide_drive_t *
 {
 	ide_hwif_t *hwif = drive->hwif;
 	struct scatterlist *sg = hwif->sg_table;
+	enum dma_data_direction dir = write ? DMA_TO_DEVICE : DMA_FROM_DEVICE;
 	struct page *page;
 #ifdef CONFIG_HIGHMEM
 	unsigned long flags;
@@ -277,7 +278,7 @@ static void ide_pio_sector(ide_drive_t *
 #ifdef CONFIG_HIGHMEM
 	local_irq_save(flags);
 #endif
-	buf = kmap_atomic(page, KM_BIO_SRC_IRQ) + offset;
+	buf = blk_kmap_atomic(page, KM_BIO_SRC_IRQ, dir) + offset;
 
 	hwif->nleft--;
 	hwif->cursg_ofs++;
@@ -293,7 +294,7 @@ static void ide_pio_sector(ide_drive_t *
 	else
 		taskfile_input_data(drive, buf, SECTOR_WORDS);
 
-	kunmap_atomic(buf, KM_BIO_SRC_IRQ);
+	blk_kunmap_atomic(buf, KM_BIO_SRC_IRQ, dir);
 #ifdef CONFIG_HIGHMEM
 	local_irq_restore(flags);
 #endif