[PATCH] libata: add per-device max_sectors

If a low level driver wants to control max_sectors, it had to adjust
ap->host->max_sectors and set ATA_DFLAG_LOCK_SECTORS to tell
ata_scsi_slave_config not to override the limit.  This is not only
cumbersome but also incorrect for hosts which support more than one
devices per port.

This patch adds per-device ->max_sectors.  If the field is unset
(zero), libata core layer will adjust ->max_sectors according to
default rules.  If the field is set, libata honors the setting.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 853c988..afe4645 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -122,8 +122,7 @@
 	/* struct ata_device stuff */
 	ATA_DFLAG_LBA48		= (1 << 0), /* device supports LBA48 */
 	ATA_DFLAG_PIO		= (1 << 1), /* device currently in PIO mode */
-	ATA_DFLAG_LOCK_SECTORS	= (1 << 2), /* don't adjust max_sectors */
-	ATA_DFLAG_LBA		= (1 << 3), /* device supports LBA */
+	ATA_DFLAG_LBA		= (1 << 2), /* device supports LBA */
 
 	ATA_DEV_UNKNOWN		= 0,	/* unknown device */
 	ATA_DEV_ATA		= 1,	/* ATA device */
@@ -348,6 +347,7 @@
 
 	unsigned int		multi_count;	/* sectors count for
 						   READ/WRITE MULTIPLE */
+	unsigned int		max_sectors;	/* per-device max sectors */
 	unsigned int		cdb_len;
 
 	/* for CHS addressing */