fsdax: decouple zeroing from the iomap buffered I/O code

Unshare the DAX and iomap buffered I/O page zeroing code.  This code
previously did a IS_DAX check deep inside the iomap code, which in
fact was the only DAX check in the code.  Instead move these checks
into the callers.  Most callers already have DAX special casing anyway
and XFS will need it for reflink support as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20211129102203.2243509-19-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 12 insertions, 23 deletions

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 1753c26c8e76..b1511255b4df 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -870,26 +870,8 @@ iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
 }
 EXPORT_SYMBOL_GPL(iomap_file_unshare);
 
-static s64 __iomap_zero_iter(struct iomap_iter *iter, loff_t pos, u64 length)
-{
-	struct page *page;
-	int status;
-	unsigned offset = offset_in_page(pos);
-	unsigned bytes = min_t(u64, PAGE_SIZE - offset, length);
-
-	status = iomap_write_begin(iter, pos, bytes, &page);
-	if (status)
-		return status;
-
-	zero_user(page, offset, bytes);
-	mark_page_accessed(page);
-
-	return iomap_write_end(iter, pos, bytes, bytes, page);
-}
-
 static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
 {
-	struct iomap *iomap = &iter->iomap;
 	const struct iomap *srcmap = iomap_iter_srcmap(iter);
 	loff_t pos = iter->pos;
 	loff_t length = iomap_length(iter);
@@ -900,12 +882,19 @@ static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
 		return length;
 
 	do {
-		s64 bytes;
+		unsigned offset = offset_in_page(pos);
+		size_t bytes = min_t(u64, PAGE_SIZE - offset, length);
+		struct page *page;
+		int status;
 
-		if (IS_DAX(iter->inode))
-			bytes = dax_iomap_zero(pos, length, iomap);
-		else
-			bytes = __iomap_zero_iter(iter, pos, length);
+		status = iomap_write_begin(iter, pos, bytes, &page);
+		if (status)
+			return status;
+
+		zero_user(page, offset, bytes);
+		mark_page_accessed(page);
+
+		bytes = iomap_write_end(iter, pos, bytes, bytes, page);
 		if (bytes < 0)
 			return bytes;