Merge tag 'block-5.5-2020-01-26' of git://git.kernel.dk/linux-block

Pull block fix from Jens Axboe:
 "Unfortunately this weekend we had a few last minute reports, one was
  for block.

  The partition disable for zoned devices was overly restrictive, it can
  work (and be supported) just fine for host-aware variants.

  Here's a fix ensuring that's the case so we don't break existing users
  of that"

* tag 'block-5.5-2020-01-26' of git://git.kernel.dk/linux-block:
  block: allow partitions on host aware zone devices

block/partition-generic.c

@@ -321,6 +321,24 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
 	const char *dname;
 	int err;
 
+	/*
+	 * Partitions are not supported on zoned block devices that are used as
+	 * such.
+	 */
+	switch (disk->queue->limits.zoned) {
+	case BLK_ZONED_HM:
+		pr_warn("%s: partitions not supported on host managed zoned block device\n",
+			disk->disk_name);
+		return ERR_PTR(-ENXIO);
+	case BLK_ZONED_HA:
+		pr_info("%s: disabling host aware zoned block device support due to partitions\n",
+			disk->disk_name);
+		disk->queue->limits.zoned = BLK_ZONED_NONE;
+		break;
+	case BLK_ZONED_NONE:
+		break;
+	}
+
 	err = disk_expand_part_tbl(disk, partno);
 	if (err)
 		return ERR_PTR(err);
@@ -501,7 +519,7 @@ static bool blk_add_partition(struct gendisk *disk, struct block_device *bdev,
 
 	part = add_partition(disk, p, from, size, state->parts[p].flags,
 			     &state->parts[p].info);
-	if (IS_ERR(part)) {
+	if (IS_ERR(part) && PTR_ERR(part) != -ENXIO) {
 		printk(KERN_ERR " %s: p%d could not be added: %ld\n",
 		       disk->disk_name, p, -PTR_ERR(part));
 		return true;
@@ -540,10 +558,10 @@ int blk_add_partitions(struct gendisk *disk, struct block_device *bdev)
 	}
 
 	/*
-	 * Partitions are not supported on zoned block devices.
+	 * Partitions are not supported on host managed zoned block devices.
 	 */
-	if (bdev_is_zoned(bdev)) {
-		pr_warn("%s: ignoring partition table on zoned block device\n",
+	if (disk->queue->limits.zoned == BLK_ZONED_HM) {
+		pr_warn("%s: ignoring partition table on host managed zoned block device\n",
 			disk->disk_name);
 		ret = 0;
 		goto out_free_state;

drivers/scsi/sd.c

@@ -2958,16 +2958,17 @@ static void sd_read_block_characteristics(struct scsi_disk *sdkp)
 		q->limits.zoned = BLK_ZONED_HM;
 	} else {
 		sdkp->zoned = (buffer[8] >> 4) & 3;
-		if (sdkp->zoned == 1)
+		if (sdkp->zoned == 1 && !disk_has_partitions(sdkp->disk)) {
 			/* Host-aware */
 			q->limits.zoned = BLK_ZONED_HA;
-		else
+		} else {
 			/*
-			 * Treat drive-managed devices as
-			 * regular block devices.
+			 * Treat drive-managed devices and host-aware devices
+			 * with partitions as regular block devices.
 			 */
 			q->limits.zoned = BLK_ZONED_NONE;
 		}
+	}
 	if (blk_queue_is_zoned(q) && sdkp->first_scan)
 		sd_printk(KERN_NOTICE, sdkp, "Host-%s zoned block device\n",
 		      q->limits.zoned == BLK_ZONED_HM ? "managed" : "aware");

include/linux/genhd.h

@@ -245,6 +245,18 @@ static inline bool disk_part_scan_enabled(struct gendisk *disk)
 		!(disk->flags & GENHD_FL_NO_PART_SCAN);
 }
 
+static inline bool disk_has_partitions(struct gendisk *disk)
+{
+	bool ret = false;
+
+	rcu_read_lock();
+	if (rcu_dereference(disk->part_tbl)->len > 1)
+		ret = true;
+	rcu_read_unlock();
+
+	return ret;
+}
+
 static inline dev_t disk_devt(struct gendisk *disk)
 {
 	return MKDEV(disk->major, disk->first_minor);