ext2, ext4: warn when mounting with dax enabled
Similar to XFS warn when mounting DAX while it is still considered under
development. Also, aspects of the DAX implementation, for example
synchronization against multiple faults and faults causing block
allocation, depend on the correct implementation in the filesystem. The
maturity of a given DAX implementation is filesystem specific.
Cc: <stable@vger.kernel.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: linux-ext4@vger.kernel.org
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Dave Chinner <david@fromorbit.com>
Acked-by: Jan Kara <jack@suse.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 753f4e6..c9ab67d 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1664,8 +1664,12 @@
}
sbi->s_jquota_fmt = m->mount_opt;
#endif
-#ifndef CONFIG_FS_DAX
} else if (token == Opt_dax) {
+#ifdef CONFIG_FS_DAX
+ ext4_msg(sb, KERN_WARNING,
+ "DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
+ sbi->s_mount_opt |= m->mount_opt;
+#else
ext4_msg(sb, KERN_INFO, "dax option not supported");
return -1;
#endif