xfs: add xfs_zero_range and xfs_truncate_page helpers

Add helpers to prepare for using different DAX operations.
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
[hch: split from a larger patch + slight cleanups]
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/20211129102203.2243509-16-hch@lst.deSigned-off-by: Dan Williams <dan.j.williams@intel.com>

fs/xfs/xfs_bmap_util.c

@@ -1001,7 +1001,7 @@ xfs_free_file_space(
 
 	/*
 	 * Now that we've unmap all full blocks we'll have to zero out any
-	 * partial block at the beginning and/or end.  iomap_zero_range is smart
+	 * partial block at the beginning and/or end.  xfs_zero_range is smart
 	 * enough to skip any holes, including those we just created, but we
 	 * must take care not to zero beyond EOF and enlarge i_size.
 	 */
@@ -1009,15 +1009,14 @@ xfs_free_file_space(
 		return 0;
 	if (offset + len > XFS_ISIZE(ip))
 		len = XFS_ISIZE(ip) - offset;
-	error = iomap_zero_range(VFS_I(ip), offset, len, NULL,
-			&xfs_buffered_write_iomap_ops);
+	error = xfs_zero_range(ip, offset, len, NULL);
 	if (error)
 		return error;
 
 	/*
 	 * If we zeroed right up to EOF and EOF straddles a page boundary we
 	 * must make sure that the post-EOF area is also zeroed because the
-	 * page could be mmap'd and iomap_zero_range doesn't do that for us.
+	 * page could be mmap'd and xfs_zero_range doesn't do that for us.
 	 * Writeback of the eof page will do this, albeit clumsily.
 	 */
 	if (offset + len >= XFS_ISIZE(ip) && offset_in_page(offset + len) > 0) {

fs/xfs/xfs_file.c

@@ -437,8 +437,7 @@ xfs_file_write_checks(
 		}
 
 		trace_xfs_zero_eof(ip, isize, iocb->ki_pos - isize);
-		error = iomap_zero_range(inode, isize, iocb->ki_pos - isize,
-				NULL, &xfs_buffered_write_iomap_ops);
+		error = xfs_zero_range(ip, isize, iocb->ki_pos - isize, NULL);
 		if (error)
 			return error;
 	} else

fs/xfs/xfs_iomap.c

@@ -1311,3 +1311,28 @@ xfs_xattr_iomap_begin(
 const struct iomap_ops xfs_xattr_iomap_ops = {
 	.iomap_begin		= xfs_xattr_iomap_begin,
 };
+
+int
+xfs_zero_range(
+	struct xfs_inode	*ip,
+	loff_t			pos,
+	loff_t			len,
+	bool			*did_zero)
+{
+	struct inode		*inode = VFS_I(ip);
+
+	return iomap_zero_range(inode, pos, len, did_zero,
+				&xfs_buffered_write_iomap_ops);
+}
+
+int
+xfs_truncate_page(
+	struct xfs_inode	*ip,
+	loff_t			pos,
+	bool			*did_zero)
+{
+	struct inode		*inode = VFS_I(ip);
+
+	return iomap_truncate_page(inode, pos, did_zero,
+				   &xfs_buffered_write_iomap_ops);
+}

fs/xfs/xfs_iomap.h

@@ -20,6 +20,10 @@ xfs_fileoff_t xfs_iomap_eof_align_last_fsb(struct xfs_inode *ip,
 int xfs_bmbt_to_iomap(struct xfs_inode *, struct iomap *,
 		struct xfs_bmbt_irec *, u16);
 
+int xfs_zero_range(struct xfs_inode *ip, loff_t pos, loff_t len,
+		bool *did_zero);
+int xfs_truncate_page(struct xfs_inode *ip, loff_t pos, bool *did_zero);
+
 static inline xfs_filblks_t
 xfs_aligned_fsb_count(
 	xfs_fileoff_t		offset_fsb,

fs/xfs/xfs_iops.c

@@ -911,8 +911,8 @@ xfs_setattr_size(
 	 */
 	if (newsize > oldsize) {
 		trace_xfs_zero_eof(ip, oldsize, newsize - oldsize);
-		error = iomap_zero_range(inode, oldsize, newsize - oldsize,
-				&did_zeroing, &xfs_buffered_write_iomap_ops);
+		error = xfs_zero_range(ip, oldsize, newsize - oldsize,
+				&did_zeroing);
 	} else {
 		/*
 		 * iomap won't detect a dirty page over an unwritten block (or a
@@ -924,8 +924,7 @@ xfs_setattr_size(
 						     newsize);
 		if (error)
 			return error;
-		error = iomap_truncate_page(inode, newsize, &did_zeroing,
-				&xfs_buffered_write_iomap_ops);
+		error = xfs_truncate_page(ip, newsize, &did_zeroing);
 	}
 
 	if (error)

fs/xfs/xfs_reflink.c

@@ -1269,8 +1269,7 @@ xfs_reflink_zero_posteof(
 		return 0;
 
 	trace_xfs_zero_eof(ip, isize, pos - isize);
-	return iomap_zero_range(VFS_I(ip), isize, pos - isize, NULL,
-			&xfs_buffered_write_iomap_ops);
+	return xfs_zero_range(ip, isize, pos - isize, NULL);
 }
 
 /*