6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Darrick J. Wong djwong@kernel.org
commit 8d16762047c627073955b7ed171a36addaf7b1ff upstream.
If a file has the S_DAX flag (aka fsdax access mode) set, we cannot allow users to change the realtime flag unless the datadev and rtdev both support fsdax access modes. Even if there are no extents allocated to the file, the setattr thread could be racing with another thread that has already started down the write code paths.
Fixes: ba23cba9b3bdc ("fs: allow per-device dax status checking for filesystems") Signed-off-by: Darrick J. Wong djwong@kernel.org Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Chandan Babu R chandanbabu@kernel.org Signed-off-by: Catherine Hoang catherine.hoang@oracle.com Acked-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/xfs/xfs_ioctl.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index df4bf0d56aad..32e718043e0e 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -1128,6 +1128,17 @@ xfs_ioctl_setattr_xflags( /* Can't change realtime flag if any extents are allocated. */ if (ip->i_df.if_nextents || ip->i_delayed_blks) return -EINVAL; + + /* + * If S_DAX is enabled on this file, we can only switch the + * device if both support fsdax. We can't update S_DAX because + * there might be other threads walking down the access paths. + */ + if (IS_DAX(VFS_I(ip)) && + (mp->m_ddev_targp->bt_daxdev == NULL || + (mp->m_rtdev_targp && + mp->m_rtdev_targp->bt_daxdev == NULL))) + return -EINVAL; }
if (rtflag) {