[parted-devel] [PATCH v2] libparted: Fail early when detecting nilfs2

[Oldřich Jedlička]

When the disk is encrypted with TCG Opal HW encryption (supported by
cryptsetup 2.7.0+), the partition initially contains locked area, which
shows reading errors in kernel logs and may lead to configuring the disk
to work with lower reading speed. When the disk area is unlocked with
password, the reading succeeds. The beginning of the protected partition is
not locked and contains LUKS header, this is always readable.

To work around the errors when reading from the locked area, try first
detecting nilfs2 at the beginning (may be an unprotected LUKS header area)
and only check the second superblock that is at the end of the area (and
possibly locked) if the first one is valid (meaning the partition is not
LUKS-protected).

This is a change in behavior, but is consistent with the nilfs2 code, which
considers both superblocks mandatory, see [1].

[1] https://github.com/nilfs-dev/nilfs-utils/blob/master/lib/sb.c#L135-L158

Signed-off-by: Oldřich Jedlička <oldium.pro at gmail.com>
---
 libparted/fs/nilfs2/nilfs2.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/libparted/fs/nilfs2/nilfs2.c b/libparted/fs/nilfs2/nilfs2.c
index 6204542..40f8567 100644
--- a/libparted/fs/nilfs2/nilfs2.c
+++ b/libparted/fs/nilfs2/nilfs2.c
@@ -118,11 +118,12 @@ nilfs2_probe (PedGeometry* geom)
 
 	if (ped_geometry_read(geom, buf, 0, sectors))
 		sb = (struct nilfs2_super_block*)(buf + 1024);
+	if (!sb || !is_valid_nilfs_sb(sb))
+		return NULL;
+
 	if (ped_geometry_read(geom, buff2, sb2off, sectors2))
 		sb2 = (struct nilfs2_super_block*)buff2;
-
-	if ((!sb || !is_valid_nilfs_sb(sb)) &&
-	    (!sb2 || !is_valid_nilfs_sb(sb2)))
+	if (!sb2 || !is_valid_nilfs_sb(sb2))
 		return NULL;
 
 	/* reserve 4k bytes for secondary superblock */
-- 
2.39.2