[PATCH v1 2/2] {topost} scsi: libsas: check link status at ATA prereset() ops

[Luo Jiaxing <luojiaxing@huawei.com>]

We found out that libata will retry reset even if SATA disk is unpluged. We
should report offline to libata to avoid meaningless reset on the disk.
Libata provide an ops of prereset() for this purpose, it was called by
ata_eh_reset() only and used to decide whether to skip reset base on the
return value of it.

We check status of phy and disk at prereset(). If disk is already offline
or phy is disabled, we return -ENOENT to libata to skip disk reset.

As prereset() should be best-effort, we should continue to try disk reset
beyond the situation we mentioned before.

Signed-off-by: Luo Jiaxing <luojiaxing@huawei.com>
Reviewed-by: John Garry <john.garry@huawei.com>
---
 drivers/scsi/libsas/sas_ata.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index a7d16d2..1b93332 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -507,8 +507,22 @@ void sas_ata_end_eh(struct ata_port *ap)
 	spin_unlock_irqrestore(&ha->lock, flags);
 }
 
+static int sas_ata_prereset(struct ata_link *link, unsigned long deadline)
+{
+	struct ata_port *ap = link->ap;
+	struct domain_device *dev = ap->private_data;
+	struct sas_phy *local_phy = sas_get_local_phy(dev);
+	int res = 0;
+
+	if (!local_phy->enabled || test_bit(SAS_DEV_GONE, &dev->state))
+		res = -ENOENT;
+	sas_put_local_phy(local_phy);
+
+	return res;
+}
+
 static struct ata_port_operations sas_sata_ops = {
-	.prereset		= ata_std_prereset,
+	.prereset		= sas_ata_prereset,
 	.hardreset		= sas_ata_hard_reset,
 	.error_handler		= ata_std_error_handler,
 	.post_internal_cmd	= sas_ata_post_internal,
-- 
2.7.4