From 5ffce3cc22a0e89813ed0c7162a68b639aef9ab6 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Fri, 4 Sep 2020 10:20:16 -0700
Subject: xfs: force the log after remapping a synchronous-writes file
Git-commit: 5ffce3cc22a0e89813ed0c7162a68b639aef9ab6
Patch-mainline: v5.10-rc1
References: git-fixes

Commit 5833112df7e9 tried to make it so that a remap operation would
force the log out to disk if the filesystem is mounted with mandatory
synchronous writes.  Unfortunately, that commit failed to handle the
case where the inode or the file descriptor require mandatory
synchronous writes.

Refactor the check into into a helper that will look for all three
conditions, and now we can treat reflink just like any other synchronous
write.

Fixes: 5833112df7e9 ("xfs: reflink should force the log out if mounted with wsync")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>

---
 fs/xfs/xfs_file.c |   17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -979,6 +979,21 @@
 	return ret;
 }
 
+/* Does this file, inode, or mount want synchronous writes? */
+static inline bool xfs_file_sync_writes(struct file *filp)
+{
+	struct xfs_inode	*ip = XFS_I(file_inode(filp));
+
+	if (ip->i_mount->m_flags & XFS_MOUNT_WSYNC)
+		return true;
+	if (filp->f_flags & (__O_SYNC | O_DSYNC))
+		return true;
+	if (IS_SYNC(file_inode(filp)))
+		return true;
+
+	return false;
+}
+
 STATIC loff_t
 xfs_file_remap_range(
 	struct file		*file_in,
@@ -1036,7 +1051,7 @@
 	if (ret)
 		goto out_unlock;
 
-	if (mp->m_flags & XFS_MOUNT_WSYNC)
+	if (xfs_file_sync_writes(file_in) || xfs_file_sync_writes(file_out))
 		xfs_log_force_inode(dest);
 out_unlock:
 	xfs_reflink_remap_unlock(file_in, file_out);