libata and bogus LBA48 drives

A colleague noticed recent versions of Ubuntu no longer detect his 80 GB
ST380020ACE drive. This drive is special in that it advertises LBA48 support,
but has the lba_capacity_2 field set to zero (cfr.
http://lkml.org/lkml/2004/3/30/163).

Upon closer look, libata indeed doesn't seem to handle this case yet.
Below is an (untested) fix.

Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/ata.h b/include/linux/ata.h
index 61535e72834d..304825b1c977 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -425,6 +425,8 @@ static inline int ata_id_has_lba48(const u16 *id)
 {
         if ((id[83] & 0xC000) != 0x4000)
                 return 0;
+        if (!ata_id_u64(id, 100))
+                return 0;
         return id[83] & (1 << 10);
 }