[PATCH 5/5] vfs: only allow FSSETXATTR to set DAX flag on files and dirs

Darrick J. Wong
2019-06-26T02:34:08Z

From: Darrick J. Wong <darrick.wong@oracle.com>

The DAX flag only applies to files and directories, so don't let it get
set for other types of files.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/inode.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/fs/inode.c b/fs/inode.c
index 670d5408d022..f08711b34341 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -2259,6 +2259,14 @@ int vfs_ioc_fssetxattr_check(struct inode *inode, const struct fsxattr *old_fa,
!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
return -EINVAL;

+ /*
+ * It is only valid to set the DAX flag on regular files and
+ * directories on filesystems.
+ */
+ if ((fa->fsx_xflags & FS_XFLAG_DAX) &&
+ !(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
+ return -EINVAL;
+
/* Extent size hints of zero turn off the flags. */
if (fa->fsx_extsize == 0)
fa->fsx_xflags &= ~(FS_XFLAG_EXTSIZE | FS_XFLAG_EXTSZINHERIT);