GFS2: Switch fiemap implementation to use iomap

This patch switches GFS2's implementation of fiemap from the old
block_map code to the new iomap interface.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/Kconfig

@@ -4,6 +4,7 @@ config GFS2_FS
 	select FS_POSIX_ACL
 	select CRC32
 	select QUOTACTL
+	select FS_IOMAP
 	help
 	  A cluster filesystem.
 

fs/gfs2/inode.c

@@ -18,7 +18,7 @@
 #include <linux/posix_acl.h>
 #include <linux/gfs2_ondisk.h>
 #include <linux/crc32.h>
-#include <linux/fiemap.h>
+#include <linux/iomap.h>
 #include <linux/security.h>
 #include <linux/uaccess.h>
 
@@ -2003,6 +2003,10 @@ static int gfs2_getattr(const struct path *path, struct kstat *stat,
 	return 0;
 }
 
+const struct iomap_ops gfs2_iomap_ops = {
+	.iomap_begin = gfs2_iomap_begin,
+};
+
 static int gfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		       u64 start, u64 len)
 {
@@ -2010,38 +2014,18 @@ static int gfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	struct gfs2_holder gh;
 	int ret;
 
-	ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC);
-	if (ret)
-		return ret;
-
-	inode_lock(inode);
+	inode_lock_shared(inode);
 
 	ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 	if (ret)
 		goto out;
 
-	if (gfs2_is_stuffed(ip)) {
-		u64 phys = ip->i_no_addr << inode->i_blkbits;
-		u64 size = i_size_read(inode);
-		u32 flags = FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_NOT_ALIGNED|
-			    FIEMAP_EXTENT_DATA_INLINE;
-		phys += sizeof(struct gfs2_dinode);
-		phys += start;
-		if (start + len > size)
-			len = size - start;
-		if (start < size)
-			ret = fiemap_fill_next_extent(fieinfo, start, phys,
-						      len, flags);
-		if (ret == 1)
-			ret = 0;
-	} else {
-		ret = __generic_block_fiemap(inode, fieinfo, start, len,
-					     gfs2_block_map);
-	}
+	ret = iomap_fiemap(inode, fieinfo, start, len, &gfs2_iomap_ops);
 
 	gfs2_glock_dq_uninit(&gh);
+
 out:
-	inode_unlock(inode);
+	inode_unlock_shared(inode);
 	return ret;
 }