[PATCH] aio: fix D-cache aliasing issues

[Helge Deller <deller@gmx.de>]

When a user page mapping is released via kunmap*() functions, the D-cache needs
to be flushed via flush_dcache_page() to avoid D-cache aliasing issues.

This patch fixes aio on the parisc platform (and probably others).

Signed-off-by: Helge Deller <deller@gmx.de>
To: Benjamin LaHaise <bcrl@kvack.org>
To: linux-aio@kvack.org
Cc: stable@vger.kernel.org    # 3.12+

diff --git a/fs/aio.c b/fs/aio.c
index 823efcb..2181821 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -514,6 +514,7 @@ static void free_ioctx(struct work_struct *work)
 		atomic_add(avail, &ctx->reqs_available);
 		ring->head = ring->tail;
 		kunmap_atomic(ring);
+		flush_dcache_page(ctx->ring_pages[0]);
 
 		if (atomic_read(&ctx->reqs_available) >= ctx->nr_events - 1)
 			break;
@@ -568,6 +569,7 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
 					ring = kmap_atomic(ctx->ring_pages[0]);
 					ring->id = ctx->id;
 					kunmap_atomic(ring);
+					flush_dcache_page(ctx->ring_pages[0]);
 					return 0;
 				}
 
@@ -1032,6 +1034,7 @@ static long aio_read_events_ring(struct kioctx *ctx,
 	head = ring->head;
 	tail = ring->tail;
 	kunmap_atomic(ring);
+	flush_dcache_page(ctx->ring_pages[0]);
 
 	pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);