s390/scm_blk: suspend writes

Stop writing to scm after certain error conditions such as a concurrent
firmware upgrade. Resume to normal state once scm_blk_set_available is
called (due to an scm availability notification).

Reviewed-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 60 insertions, 5 deletions

diff --git a/arch/s390/include/asm/eadm.h b/arch/s390/include/asm/eadm.h
index a4a1ea49003..78141be88b3 100644
--- a/arch/s390/include/asm/eadm.h
+++ b/arch/s390/include/asm/eadm.h
@@ -34,6 +34,8 @@ struct arsb {
         u32 reserved[4];
 } __packed;
 
+#define EQC_WR_PROHIBIT 22
+
 struct msb {
         u8 fmt:4;
         u8 oc:4;
diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
index d9c7e940fa3..5ac9c935c15 100644
--- a/drivers/s390/block/scm_blk.c
+++ b/drivers/s390/block/scm_blk.c
@@ -135,6 +135,11 @@ static const struct block_device_operations scm_blk_devops = {
         .release = scm_release,
 };
 
+static bool scm_permit_request(struct scm_blk_dev *bdev, struct request *req)
+{
+        return rq_data_dir(req) != WRITE || bdev->state != SCM_WR_PROHIBIT;
+}
+
 static void scm_request_prepare(struct scm_request *scmrq)
 {
         struct scm_blk_dev *bdev = scmrq->bdev;
@@ -222,6 +227,10 @@ static void scm_blk_request(struct request_queue *rq)
                 if (req->cmd_type != REQ_TYPE_FS)
                         continue;
 
+                if (!scm_permit_request(bdev, req)) {
+                        scm_ensure_queue_restart(bdev);
+                        return;
+                }
                 scmrq = scm_request_fetch();
                 if (!scmrq) {
                         SCM_LOG(5, "no request");
@@ -285,6 +294,38 @@ void scm_blk_irq(struct scm_device *scmdev, void *data, int error)
         tasklet_hi_schedule(&bdev->tasklet);
 }
 
+static void scm_blk_handle_error(struct scm_request *scmrq)
+{
+        struct scm_blk_dev *bdev = scmrq->bdev;
+        unsigned long flags;
+
+        if (scmrq->error != -EIO)
+                goto restart;
+
+        /* For -EIO the response block is valid. */
+        switch (scmrq->aob->response.eqc) {
+        case EQC_WR_PROHIBIT:
+                spin_lock_irqsave(&bdev->lock, flags);
+                if (bdev->state != SCM_WR_PROHIBIT)
+                        pr_info("%lu: Write access to the SCM increment is suspended\n",
+                                (unsigned long) bdev->scmdev->address);
+                bdev->state = SCM_WR_PROHIBIT;
+                spin_unlock_irqrestore(&bdev->lock, flags);
+                goto requeue;
+        default:
+                break;
+        }
+
+restart:
+        if (!scm_start_aob(scmrq->aob))
+                return;
+
+requeue:
+        spin_lock_irqsave(&bdev->rq_lock, flags);
+        scm_request_requeue(scmrq);
+        spin_unlock_irqrestore(&bdev->rq_lock, flags);
+}
+
 static void scm_blk_tasklet(struct scm_blk_dev *bdev)
 {
         struct scm_request *scmrq;
@@ -298,11 +339,8 @@ static void scm_blk_tasklet(struct scm_blk_dev *bdev)
                 spin_unlock_irqrestore(&bdev->lock, flags);
 
                 if (scmrq->error && scmrq->retries-- > 0) {
-                        if (scm_start_aob(scmrq->aob)) {
-                                spin_lock_irqsave(&bdev->rq_lock, flags);
-                                scm_request_requeue(scmrq);
-                                spin_unlock_irqrestore(&bdev->rq_lock, flags);
-                        }
+                        scm_blk_handle_error(scmrq);
+
                         /* Request restarted or requeued, handle next. */
                         spin_lock_irqsave(&bdev->lock, flags);
                         continue;
@@ -336,6 +374,7 @@ int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
         }
 
         bdev->scmdev = scmdev;
+        bdev->state = SCM_OPER;
         spin_lock_init(&bdev->rq_lock);
         spin_lock_init(&bdev->lock);
         INIT_LIST_HEAD(&bdev->finished_requests);
@@ -400,6 +439,18 @@ void scm_blk_dev_cleanup(struct scm_blk_dev *bdev)
         put_disk(bdev->gendisk);
 }
 
+void scm_blk_set_available(struct scm_blk_dev *bdev)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&bdev->lock, flags);
+        if (bdev->state == SCM_WR_PROHIBIT)
+                pr_info("%lu: Write access to the SCM increment is restored\n",
+                        (unsigned long) bdev->scmdev->address);
+        bdev->state = SCM_OPER;
+        spin_unlock_irqrestore(&bdev->lock, flags);
+}
+
 static int __init scm_blk_init(void)
 {
         int ret = -EINVAL;
diff --git a/drivers/s390/block/scm_blk.h b/drivers/s390/block/scm_blk.h
index 3c1ccf49464..8b387b32fd6 100644
--- a/drivers/s390/block/scm_blk.h
+++ b/drivers/s390/block/scm_blk.h
@@ -21,6 +21,7 @@ struct scm_blk_dev {
         spinlock_t rq_lock;     /* guard the request queue */
         spinlock_t lock;        /* guard the rest of the blockdev */
         atomic_t queued_reqs;
+        enum {SCM_OPER, SCM_WR_PROHIBIT} state;
         struct list_head finished_requests;
 #ifdef CONFIG_SCM_BLOCK_CLUSTER_WRITE
         struct list_head cluster_list;
@@ -48,6 +49,7 @@ struct scm_request {
 
 int scm_blk_dev_setup(struct scm_blk_dev *, struct scm_device *);
 void scm_blk_dev_cleanup(struct scm_blk_dev *);
+void scm_blk_set_available(struct scm_blk_dev *);
 void scm_blk_irq(struct scm_device *, void *, int);
 
 void scm_request_finish(struct scm_request *);