Re: [PATCH v2] xfs: don't set v3 xflags for v2 inodes

[Christoph Hellwig <hch@infradead.org>]

So maybe something like this (totally untested, will attempt for
a QA run over the night):


>From d4da594cd1c42b88673b7eae5187827a3099ec42 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Thu, 31 Aug 2017 15:14:36 +0200
Subject: xfs: don't set v3 xflags for v2 inodes

Reject attempts to set XFLAGS that correspond to di_flags2 inode flags
if the inode isn't a v3 inode, because di_flags2 only exists on v3.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_ioctl.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 9c0c7a920304..84a80210b2e1 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -931,7 +931,7 @@ xfs_ioc_fsgetxattr(
 	return 0;
 }
 
-STATIC void
+STATIC int
 xfs_set_diflags(
 	struct xfs_inode	*ip,
 	unsigned int		xflags)
@@ -970,11 +970,6 @@ xfs_set_diflags(
 		if (xflags & FS_XFLAG_EXTSIZE)
 			di_flags |= XFS_DIFLAG_EXTSIZE;
 	}
-	ip->i_d.di_flags = di_flags;
-
-	/* diflags2 only valid for v3 inodes. */
-	if (ip->i_d.di_version < 3)
-		return;
 
 	di_flags2 = (ip->i_d.di_flags2 & XFS_DIFLAG2_REFLINK);
 	if (xflags & FS_XFLAG_DAX)
@@ -982,7 +977,13 @@ xfs_set_diflags(
 	if (xflags & FS_XFLAG_COWEXTSIZE)
 		di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
 
+	/* diflags2 only valid for v3 inodes. */
+	if (di_flags2 && ip->i_d.di_version < 3)
+		return -EINVAL;
+
+	ip->i_d.di_flags = di_flags;
 	ip->i_d.di_flags2 = di_flags2;
+	return 0;
 }
 
 STATIC void
@@ -1022,6 +1023,7 @@ xfs_ioctl_setattr_xflags(
 	struct fsxattr		*fa)
 {
 	struct xfs_mount	*mp = ip->i_mount;
+	int			error;
 
 	/* Can't change realtime flag if any extents are allocated. */
 	if ((ip->i_d.di_nextents || ip->i_delayed_blks) &&
@@ -1052,7 +1054,10 @@ xfs_ioctl_setattr_xflags(
 	    !capable(CAP_LINUX_IMMUTABLE))
 		return -EPERM;
 
-	xfs_set_diflags(ip, fa->fsx_xflags);
+	error = xfs_set_diflags(ip, fa->fsx_xflags);
+	if (error)
+		return error;
+
 	xfs_diflags_to_linux(ip);
 	xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
-- 
2.11.0