[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>

4 files changed, 13 insertions, 17 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 1a373b4d0e22..61cba39a6834 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1147,9 +1147,7 @@ void ata_dev_config(struct ata_port *ap, unsigned int i)
                 printk(KERN_INFO "ata%u(%u): applying bridge limits\n",
                        ap->id, i);
                 ap->udma_mask &= ATA_UDMA5;
-                ap->host->max_sectors = ATA_MAX_SECTORS;
-                ap->host->hostt->max_sectors = ATA_MAX_SECTORS;
-                ap->device[i].flags |= ATA_DFLAG_LOCK_SECTORS;
+                ap->device[i].max_sectors = ATA_MAX_SECTORS;
         }
 
         if (ap->ops->dev_config)
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
diff --git a/drivers/scsi/sata_sil.c b/drivers/scsi/sata_sil.c
index 61c4ac7ff9db..6c482c8be254 100644
--- a/drivers/scsi/sata_sil.c
+++ b/drivers/scsi/sata_sil.c
@@ -354,9 +354,7 @@ static void sil_dev_config(struct ata_port *ap, struct ata_device *dev)
              (quirks & SIL_QUIRK_MOD15WRITE))) {
                 printk(KERN_INFO "ata%u(%u): applying Seagate errata fix (mod15write workaround)\n",
                        ap->id, dev->devno);
-                ap->host->max_sectors = 15;
-                ap->host->hostt->max_sectors = 15;
-                dev->flags |= ATA_DFLAG_LOCK_SECTORS;
+                dev->max_sectors = 15;
                 return;
         }
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 853c98859a9f..afe46457124e 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -122,8 +122,7 @@ enum {
         /* 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 @@ struct ata_device {
 
         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 */