[PATCH 04/15] fs: support DAX based iomap zeroing

Christoph Hellwig
2016-05-09T08:47:44Z

This avoid needing a separate inefficient get_block based DAX zero_range
implementation in file systems.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/iomap.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/fs/iomap.c b/fs/iomap.c
index fac9285..f84c6eb 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -24,6 +24,7 @@
#include <linux/uio.h>
#include <linux/backing-dev.h>
#include <linux/buffer_head.h>
+#include <linux/dax.h>
#include "internal.h"

typedef loff_t (*iomap_actor_t)(struct inode *inode, loff_t pos, loff_t len,
@@ -268,6 +269,15 @@ static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
return iomap_write_end(inode, pos, bytes, bytes, page);
}

+static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
+ struct iomap *iomap)
+{
+ sector_t sector = iomap->blkno +
+ (((pos & ~(PAGE_SIZE - 1)) - iomap->offset) >> 9);
+
+ return __dax_zero_page_range(iomap->bdev, sector, offset, bytes);
+}
+
static loff_t
iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
void *data, struct iomap *iomap)
@@ -286,7 +296,10 @@ iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
offset = pos & (PAGE_SIZE - 1); /* Within page */
bytes = min_t(unsigned, PAGE_SIZE - offset, count);

- status = iomap_zero(inode, pos, offset, bytes, iomap);
+ if (IS_DAX(inode))
+ status = iomap_dax_zero(pos, offset, bytes, iomap);
+ else
+ status = iomap_zero(inode, pos, offset, bytes, iomap);
if (status < 0)
return status;