libata: fix ata_id_logical_per_physical_sectors

The value we get from the low byte of the ATA_ID_SECTOR_SIZE word is not not
a plain multiple, but the log of it, so fix the helper to give the correct
answer.  Without this we'll get an incorrect minimal I/O size in the block
limits VPD page for 4k sector drives.

Also change the return value of ata_id_logical_per_physical_sectors to u16
for the unlikely case of very large logical sectors.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

diff --git a/include/linux/ata.h b/include/linux/ata.h
index 38a6948ce0c2cd7a50917c1a82570d851196f053..20f31567ccee324d4218dc65527412c4bf032c9a 100644 (file)
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -647,9 +647,9 @@ static inline int ata_id_has_large_logical_sectors(const u16 *id)
        return id[ATA_ID_SECTOR_SIZE] & (1 << 13);
 }
 
-static inline u8 ata_id_logical_per_physical_sectors(const u16 *id)
+static inline u16 ata_id_logical_per_physical_sectors(const u16 *id)
 {
-       return id[ATA_ID_SECTOR_SIZE] & 0xf;
+       return 1 << (id[ATA_ID_SECTOR_SIZE] & 0xf);
 }
 
 static inline int ata_id_has_lba48(const u16 *id)