[PATCH 1/6] iomap: support DAX based zeroing

[Christoph Hellwig <hch@xxxxxx>]

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

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/iomap.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/iomap.c b/fs/iomap.c
index 28a8fcb..a3e7dea 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,
@@ -264,6 +265,15 @@ iomap_zero_range_actor(struct inode *inode, loff_t pos, 
loff_t count,
        if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
                return count;
 
+#ifdef CONFIG_FS_DAX
+       if (IS_DAX(inode)) {
+               status = dax_clear_sectors(iomap->bdev, iomap->blkno, count);
+               if (status)
+                       return status;
+               return count;
+       }
+#endif
+
        do {
                unsigned offset, bytes;
 
-- 
2.1.4