3 files changed, 101 insertions, 2 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 35b621293831..6001aae0b884 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6077,6 +6077,9 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
         INIT_WORK(&ap->scsi_rescan_task, ata_scsi_dev_rescan);
         INIT_LIST_HEAD(&ap->eh_done_q);
         init_waitqueue_head(&ap->eh_wait_q);
+        init_timer_deferrable(&ap->fastdrain_timer);
+        ap->fastdrain_timer.function = ata_eh_fastdrain_timerfn;
+        ap->fastdrain_timer.data = (unsigned long)ap;
 
         ap->cbl = ATA_CBL_NONE;
 
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index e7e2ba24ce66..ac6ceed4bb60 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -56,6 +56,7 @@ enum {
  */
 enum {
         ATA_EH_PRERESET_TIMEOUT         = 10 * HZ,
+        ATA_EH_FASTDRAIN_INTERVAL       = 3 * HZ,
 };
 
 /* The following table determines how we sequence resets.  Each entry
@@ -361,6 +362,9 @@ void ata_scsi_error(struct Scsi_Host *host)
  repeat:
         /* invoke error handler */
         if (ap->ops->error_handler) {
+                /* kill fast drain timer */
+                del_timer_sync(&ap->fastdrain_timer);
+
                 /* process port resume request */
                 ata_eh_handle_port_resume(ap);
 
@@ -576,6 +580,94 @@ void ata_eng_timeout(struct ata_port *ap)
         DPRINTK("EXIT\n");
 }
 
+static int ata_eh_nr_in_flight(struct ata_port *ap)
+{
+        unsigned int tag;
+        int nr = 0;
+
+        /* count only non-internal commands */
+        for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++)
+                if (ata_qc_from_tag(ap, tag))
+                        nr++;
+
+        return nr;
+}
+
+void ata_eh_fastdrain_timerfn(unsigned long arg)
+{
+        struct ata_port *ap = (void *)arg;
+        unsigned long flags;
+        int cnt;
+
+        spin_lock_irqsave(ap->lock, flags);
+
+        cnt = ata_eh_nr_in_flight(ap);
+
+        /* are we done? */
+        if (!cnt)
+                goto out_unlock;
+
+        if (cnt == ap->fastdrain_cnt) {
+                unsigned int tag;
+
+                /* No progress during the last interval, tag all
+                 * in-flight qcs as timed out and freeze the port.
+                 */
+                for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++) {
+                        struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);
+                        if (qc)
+                                qc->err_mask |= AC_ERR_TIMEOUT;
+                }
+
+                ata_port_freeze(ap);
+        } else {
+                /* some qcs have finished, give it another chance */
+                ap->fastdrain_cnt = cnt;
+                ap->fastdrain_timer.expires =
+                        jiffies + ATA_EH_FASTDRAIN_INTERVAL;
+                add_timer(&ap->fastdrain_timer);
+        }
+
+ out_unlock:
+        spin_unlock_irqrestore(ap->lock, flags);
+}
+
+/**
+ *      ata_eh_set_pending - set ATA_PFLAG_EH_PENDING and activate fast drain
+ *      @ap: target ATA port
+ *      @fastdrain: activate fast drain
+ *
+ *      Set ATA_PFLAG_EH_PENDING and activate fast drain if @fastdrain
+ *      is non-zero and EH wasn't pending before.  Fast drain ensures
+ *      that EH kicks in in timely manner.
+ *
+ *      LOCKING:
+ *      spin_lock_irqsave(host lock)
+ */
+static void ata_eh_set_pending(struct ata_port *ap, int fastdrain)
+{
+        int cnt;
+
+        /* already scheduled? */
+        if (ap->pflags & ATA_PFLAG_EH_PENDING)
+                return;
+
+        ap->pflags |= ATA_PFLAG_EH_PENDING;
+
+        if (!fastdrain)
+                return;
+
+        /* do we have in-flight qcs? */
+        cnt = ata_eh_nr_in_flight(ap);
+        if (!cnt)
+                return;
+
+        /* activate fast drain */
+        ap->fastdrain_cnt = cnt;
+        ap->fastdrain_timer.expires = jiffies + ATA_EH_FASTDRAIN_INTERVAL;
+        add_timer(&ap->fastdrain_timer);
+}
+
 /**
  *      ata_qc_schedule_eh - schedule qc for error handling
  *      @qc: command to schedule error handling for
@@ -593,7 +685,7 @@ void ata_qc_schedule_eh(struct ata_queued_cmd *qc)
         WARN_ON(!ap->ops->error_handler);
 
         qc->flags |= ATA_QCFLAG_FAILED;
-        qc->ap->pflags |= ATA_PFLAG_EH_PENDING;
+        ata_eh_set_pending(ap, 1);
 
         /* The following will fail if timeout has already expired.
          * ata_scsi_error() takes care of such scmds on EH entry.
@@ -620,7 +712,7 @@ void ata_port_schedule_eh(struct ata_port *ap)
         if (ap->pflags & ATA_PFLAG_INITIALIZING)
                 return;
 
-        ap->pflags |= ATA_PFLAG_EH_PENDING;
+        ata_eh_set_pending(ap, 1);
         scsi_schedule_eh(ap->scsi_host);
 
         DPRINTK("port EH scheduled\n");
@@ -644,6 +736,9 @@ int ata_port_abort(struct ata_port *ap)
 
         WARN_ON(!ap->ops->error_handler);
 
+        /* we're gonna abort all commands, no need for fast drain */
+        ata_eh_set_pending(ap, 0);
+
         for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
                 struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);
 
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 48836b22ce2f..564cd234c805 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -151,6 +151,7 @@ extern int ata_bus_probe(struct ata_port *ap);
 extern enum scsi_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd);
 extern void ata_scsi_error(struct Scsi_Host *host);
 extern void ata_port_wait_eh(struct ata_port *ap);
+extern void ata_eh_fastdrain_timerfn(unsigned long arg);
 extern void ata_qc_schedule_eh(struct ata_queued_cmd *qc);
 
 /* libata-sff.c */