This helpers converts offset which XFS uses to store fsverity metadata
on disk to the offset in the pagecache.

Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
---
 fs/xfs/xfs_fsverity.c | 14 ++++++++++++++
 fs/xfs/xfs_fsverity.h | 13 +++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/fs/xfs/xfs_fsverity.c b/fs/xfs/xfs_fsverity.c
index 47add19a241e..4b918eb746d7 100644
--- a/fs/xfs/xfs_fsverity.c
+++ b/fs/xfs/xfs_fsverity.c
@@ -8,6 +8,20 @@
 #include "xfs_fsverity.h"
 #include <linux/fsverity.h>
 
+loff_t
+xfs_fsverity_offset_to_disk(struct xfs_inode *ip, loff_t offset)
+{
+	return (offset - fsverity_metadata_offset(VFS_I(ip))) |
+	       XFS_FSVERITY_REGION_START;
+}
+
+loff_t
+xfs_fsverity_offset_from_disk(struct xfs_inode *ip, loff_t offset)
+{
+	return (offset ^ XFS_FSVERITY_REGION_START) +
+	       fsverity_metadata_offset(VFS_I(ip));
+}
+
 bool
 xfs_fsverity_sealed_data(
 	const struct xfs_inode	*ip,
diff --git a/fs/xfs/xfs_fsverity.h b/fs/xfs/xfs_fsverity.h
index 5fc55f42b317..6f3d60f010d8 100644
--- a/fs/xfs/xfs_fsverity.h
+++ b/fs/xfs/xfs_fsverity.h
@@ -10,6 +10,8 @@
 #ifdef CONFIG_FS_VERITY
 bool xfs_fsverity_sealed_data(const struct xfs_inode *ip,
 		loff_t offset);
+loff_t xfs_fsverity_offset_to_disk(struct xfs_inode *ip, loff_t pos);
+loff_t xfs_fsverity_offset_from_disk(struct xfs_inode *ip, loff_t offset);
 #else
 static inline loff_t xfs_fsverity_offset_to_disk(struct xfs_inode *ip,
 						 loff_t pos)
@@ -17,6 +19,17 @@ static inline loff_t xfs_fsverity_offset_to_disk(struct xfs_inode *ip,
 	WARN_ON_ONCE(1);
 	return ULLONG_MAX;
 }
+static inline loff_t xfs_fsverity_offset_from_disk(struct xfs_inode *ip,
+						   loff_t offset)
+{
+	WARN_ON_ONCE(1);
+	return ULLONG_MAX;
+}
+static inline bool xfs_fsverity_sealed_data(const struct xfs_inode *ip,
+					    loff_t offset)
+{
+	return false;
+}
 #endif	/* CONFIG_FS_VERITY */
 
 #endif	/* __XFS_FSVERITY_H__ */
-- 
2.51.2