[PATCH 2/2] xfs: only set extent size hint when asked

[Dave Chinner]

From: Dave Chinner <dchinner at redhat.com>

Currently the extent size hint is set unconditionally in
xfs_ioctl_setattr(), even when the FSX_EXTSIZE flag is not set. This
means we can set values from uninitialised stack variables. Hence
only set the extent size hint from userspace when both the mask
falg is set and the inode has the XFS_DIFLAG_EXTSIZE flag set to
indicate that we should have an extent size hint set on the inode.

Signed-off-by: Dave Chinner <dchinner at redhat.com>
---
 fs/xfs/xfs_ioctl.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 87c3bd1..24c926b 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1231,13 +1231,25 @@ xfs_ioctl_setattr(
 
 	}
 
-	if (mask & FSX_EXTSIZE)
-		ip->i_d.di_extsize = fa->fsx_extsize >> mp->m_sb.sb_blocklog;
 	if (mask & FSX_XFLAGS) {
 		xfs_set_diflags(ip, fa->fsx_xflags);
 		xfs_diflags_to_linux(ip);
 	}
 
+	/*
+	 * Only set the extent size hint if we've already determined that the
+	 * extent size hint should be set on the inode. If no extent size flags
+	 * are set on the inode then unconditionally clear the extent size hint.
+	 */
+	if (mask & FSX_EXTSIZE) {
+		int	extsize = 0;
+
+		if (ip->i_d.di_flags &
+				(XFS_DIFLAG_EXTSIZE | XFS_DIFLAG_EXTSZINHERIT))
+			extsize = fa->fsx_extsize >> mp->m_sb.sb_blocklog;
+		ip->i_d.di_extsize = extsize;
+	}
+
 	xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
-- 
2.0.0