s390/dasd: retry partition detection

In case somebody attempted to open the device during online
processing the partition detection ioctl may have failed.

Added a retry loop to avoid not detected partitions.

Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 24 insertions, 2 deletions

diff --git a/drivers/s390/block/dasd_genhd.c b/drivers/s390/block/dasd_genhd.c
index f224d59c4b6b..90f39f79f5d7 100644
--- a/drivers/s390/block/dasd_genhd.c
+++ b/drivers/s390/block/dasd_genhd.c
@@ -99,15 +99,37 @@ void dasd_gendisk_free(struct dasd_block *block)
 int dasd_scan_partitions(struct dasd_block *block)
 {
         struct block_device *bdev;
+        int retry, rc;
 
+        retry = 5;
         bdev = bdget_disk(block->gdp, 0);
-        if (!bdev || blkdev_get(bdev, FMODE_READ, NULL) < 0)
+        if (!bdev) {
+                DBF_DEV_EVENT(DBF_ERR, block->base, "%s",
+                              "scan partitions error, bdget returned NULL");
                 return -ENODEV;
+        }
+
+        rc = blkdev_get(bdev, FMODE_READ, NULL);
+        if (rc < 0) {
+                DBF_DEV_EVENT(DBF_ERR, block->base,
+                              "scan partitions error, blkdev_get returned %d",
+                              rc);
+                return -ENODEV;
+        }
         /*
          * See fs/partition/check.c:register_disk,rescan_partitions
          * Can't call rescan_partitions directly. Use ioctl.
          */
-        ioctl_by_bdev(bdev, BLKRRPART, 0);
+        rc = ioctl_by_bdev(bdev, BLKRRPART, 0);
+        while (rc == -EBUSY && retry > 0) {
+                schedule();
+                rc = ioctl_by_bdev(bdev, BLKRRPART, 0);
+                retry--;
+                DBF_DEV_EVENT(DBF_ERR, block->base,
+                              "scan partitions error, retry %d rc %d",
+                              retry, rc);
+        }
+
         /*
          * Since the matching blkdev_put call to the blkdev_get in
          * this function is not called before dasd_destroy_partitions