Patch "xfs: force the log after remapping a synchronous-writes file" has been added to the 5.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    xfs: force the log after remapping a synchronous-writes file

to the 5.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xfs-force-the-log-after-remapping-a-synchronous-writ.patch
and it can be found in the queue-5.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 76f1cc4ebd6117dab59b426f5a7a5e1d77e5f5ac
Author: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Date:   Fri Sep 4 10:20:16 2020 -0700

    xfs: force the log after remapping a synchronous-writes file
    
    [ Upstream commit 5ffce3cc22a0e89813ed0c7162a68b639aef9ab6 ]
    
    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@xxxxxxxxxx>
    Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
    Reviewed-by: Christoph Hellwig <hch@xxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index a29f78a663ca5..3d1b951247440 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1008,6 +1008,21 @@ xfs_file_fadvise(
 	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,
@@ -1065,7 +1080,7 @@ xfs_file_remap_range(
 	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_iunlock2_io_mmap(src, dest);