ext4: use EXT_MAX_BLOCKS in ext4_es_can_be_merged()
ext4: use EXT_MAX_BLOCKS in ext4_es_can_be_merged()

In ext4_es_can_be_merged() when checking whether we can merge two
extents we should use EXT_MAX_BLOCKS instead of defining it manually.
Also if it is really the case we should notify userspace because clearly
there is a bug in extent status tree implementation since this should
never happen.

Signed-off-by: Lukas Czerner <6c9141d0e2318b390a8a6bf8ecd9f819d16f05b4@redhat.com>
Signed-off-by: "Theodore Ts'o" <4ed386e0495d3e109932df055831d9ec2f824927@mit.edu>
Reviewed-by: Zheng Liu <927570c33013ae711b16b2f69d88304bb3fcc969@taobao.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs