From: Darrick J. Wong <redacted>

Before we share blocks between files, we need to break the pnfs leases
on the layout before we start slicing and dicing the block map.

Signed-off-by: Darrick J. Wong <redacted>
---
 fs/xfs/xfs_reflink.c |   32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index da5c490..a701336 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c

@@ -1249,6 +1249,34 @@ xfs_reflink_remap_blocks(
 }
 
 /*
+ * Grab the exclusive iolock for a data copy from in to out, making sure to
+ * break the pnfs layout leases on out before proceeding.
+ */
+static int
+xfs_iolock_two_inodes_and_break_layout(
+	struct inode		*inode_in,
+	struct inode		*inode_out)
+{
+	uint			iolock = XFS_IOLOCK_EXCL;
+	int			error;
+
+	if (inode_in < inode_out) {
+		inode_lock(inode_in);
+		inode_lock_nested(inode_out, I_MUTEX_NONDIR2);
+	} else {
+		inode_lock(inode_out);
+	}
+	error = xfs_break_layouts(inode_out, &iolock);
+	if (error) {
+		inode_unlock(inode_in);
+		return error;
+	}
+	if (inode_in > inode_out)
+		inode_lock_nested(inode_in, I_MUTEX_NONDIR2);
+	return 0;