[PATCH 4.16 140/272] ext4: dont complain about incorrect features when probing

Greg Kroah-Hartman
2018-05-28T11:10:31Z

From: Eric Sandeen <sandeen@redhat.com>

[ Upstream commit 0d9366d67bcf066b028e57d09c9a86ce879bcc28 ]

If mount is auto-probing for filesystem type, it will try various
filesystems in order, with the MS_SILENT flag set. We get
that flag as the silent arg to ext4_fill_super.

If we're probing (silent==1) then don't complain about feature
incompatibilities that are found if it looks like it's actually
a different valid extN type - failed probes should be silent
in this case.

If the on-disk features are unknown even to ext4, then complain.

Reported-by: Joakim Tjernlund <Joakim.Tjernlund@infinera.com>
Tested-by: Joakim Tjernlund <Joakim.Tjernlund@infinera.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ext4/super.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3663,6 +3663,12 @@ static int ext4_fill_super(struct super_
ext4_msg(sb, KERN_INFO, "mounting ext2 file system "
"using the ext4 subsystem");
else {
+ /*
+ * If we're probing be silent, if this looks like
+ * it's actually an ext[34] filesystem.
+ */
+ if (silent && ext4_feature_set_ok(sb, sb_rdonly(sb)))
+ goto failed_mount;
ext4_msg(sb, KERN_ERR, "couldn't mount as ext2 due "
"to feature incompatibilities");
goto failed_mount;
@@ -3674,6 +3680,12 @@ static int ext4_fill_super(struct super_
ext4_msg(sb, KERN_INFO, "mounting ext3 file system "
"using the ext4 subsystem");
else {
+ /*
+ * If we're probing be silent, if this looks like
+ * it's actually an ext4 filesystem.
+ */
+ if (silent && ext4_feature_set_ok(sb, sb_rdonly(sb)))
+ goto failed_mount;
ext4_msg(sb, KERN_ERR, "couldn't mount as ext3 due "
"to feature incompatibilities");
goto failed_mount;