[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>

1 files changed, 9 insertions, 9 deletions

diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 3628fedc9865..86da46502b3e 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -684,23 +684,23 @@ int ata_scsi_slave_config(struct scsi_device *sdev)
         if (sdev->id < ATA_MAX_DEVICES) {
                 struct ata_port *ap;
                 struct ata_device *dev;
+                unsigned int max_sectors;
 
                 ap = (struct ata_port *) &sdev->host->hostdata[0];
                 dev = &ap->device[sdev->id];
 
-                /* TODO: 1024 is an arbitrary number, not the
+                /* TODO: 2048 is an arbitrary number, not the
                  * hardware maximum.  This should be increased to
                  * 65534 when Jens Axboe's patch for dynamically
                  * determining max_sectors is merged.
                  */
-                if ((dev->flags & ATA_DFLAG_LBA48) &&
-                    ((dev->flags & ATA_DFLAG_LOCK_SECTORS) == 0)) {
-                        /*
-                         * do not overwrite sdev->host->max_sectors, since
-                         * other drives on this host may not support LBA48
-                         */
-                        blk_queue_max_sectors(sdev->request_queue, 2048);
-                }
+                max_sectors = ATA_MAX_SECTORS;
+                if (dev->flags & ATA_DFLAG_LBA48)
+                        max_sectors = 2048;
+                if (dev->max_sectors)
+                        max_sectors = dev->max_sectors;
+
+                blk_queue_max_sectors(sdev->request_queue, max_sectors);
 
                 /*
                  * SATA DMA transfers must be multiples of 4 byte, so