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: <[email protected]> Cc: "Theodore Ts'o" <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: [email protected] Cc: Kirill A. Shutemov <[email protected]> Reported-by: Dave Chinner <[email protected]> Acked-by: Jan Kara <[email protected]> Signed-off-by: Dan Williams <[email protected]>
iegor · Nov 16, 2015 · ef83b6e · ef83b6e
1 parent 8005c49
commit ef83b6e
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diff --git a/fs/ext2/super.c b/fs/ext2/super.c
@@ -569,6 +569,8 @@ static int parse_options(char *options, struct super_block *sb)
 			/* Fall through */
 		case Opt_dax:
 #ifdef CONFIG_FS_DAX
+			ext2_msg(sb, KERN_WARNING,
+		"DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
 			set_opt(sbi->s_mount_opt, DAX);
 #else
 			ext2_msg(sb, KERN_INFO, "dax option not supported");

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
@@ -1664,8 +1664,12 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 		}
 		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