block: Remove partition support for zoned block devices

No known partitioning tool supports zoned block devices, especially the
host managed flavor with strong sequential write constraints.
Furthermore, there are also no known user nor use cases for partitioned
zoned block devices.

This patch removes partition device creation for zoned block devices,
which allows simplifying the processing of zone commands for zoned
block devices. A warning is added if a partition table is found on the
device.

For report zones operations no zone sector information remapping is
necessary anymore, simplifying the code. Of note is that remapping of
zone reports for DM targets is still necessary as done by
dm_remap_zone_report().

Similarly, remaping of a zone reset bio is not necessary anymore.
Testing for the applicability of the zone reset all request also becomes
simpler and only needs to check that the number of sectors of the
requested zone range is equal to the disk capacity.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 9 insertions, 65 deletions

diff --git a/block/partition-generic.c b/block/partition-generic.c
index aee643ce13d1..31bff3fb28af 100644
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -459,56 +459,6 @@ static int drop_partitions(struct gendisk *disk, struct block_device *bdev)
 	return 0;
 }
 
-static bool part_zone_aligned(struct gendisk *disk,
-			      struct block_device *bdev,
-			      sector_t from, sector_t size)
-{
-	unsigned int zone_sectors = bdev_zone_sectors(bdev);
-
-	/*
-	 * If this function is called, then the disk is a zoned block device
-	 * (host-aware or host-managed). This can be detected even if the
-	 * zoned block device support is disabled (CONFIG_BLK_DEV_ZONED not
-	 * set). In this case, however, only host-aware devices will be seen
-	 * as a block device is not created for host-managed devices. Without
-	 * zoned block device support, host-aware drives can still be used as
-	 * regular block devices (no zone operation) and their zone size will
-	 * be reported as 0. Allow this case.
-	 */
-	if (!zone_sectors)
-		return true;
-
-	/*
-	 * Check partition start and size alignement. If the drive has a
-	 * smaller last runt zone, ignore it and allow the partition to
-	 * use it. Check the zone size too: it should be a power of 2 number
-	 * of sectors.
-	 */
-	if (WARN_ON_ONCE(!is_power_of_2(zone_sectors))) {
-		u32 rem;
-
-		div_u64_rem(from, zone_sectors, &rem);
-		if (rem)
-			return false;
-		if ((from + size) < get_capacity(disk)) {
-			div_u64_rem(size, zone_sectors, &rem);
-			if (rem)
-				return false;
-		}
-
-	} else {
-
-		if (from & (zone_sectors - 1))
-			return false;
-		if ((from + size) < get_capacity(disk) &&
-		    (size & (zone_sectors - 1)))
-			return false;
-
-	}
-
-	return true;
-}
-
 int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
 {
 	struct parsed_partitions *state = NULL;
@@ -544,6 +494,14 @@ rescan:
 		}
 		return -EIO;
 	}
+
+	/* Partitions are not supported on zoned block devices */
+	if (bdev_is_zoned(bdev)) {
+		pr_warn("%s: ignoring partition table on zoned block device\n",
+			disk->disk_name);
+		goto out;
+	}
+
 	/*
 	 * If any partition code tried to read beyond EOD, try
 	 * unlocking native capacity even if partition table is
@@ -607,21 +565,6 @@ rescan:
 			}
 		}
 
-		/*
-		 * On a zoned block device, partitions should be aligned on the
-		 * device zone size (i.e. zone boundary crossing not allowed).
-		 * Otherwise, resetting the write pointer of the last zone of
-		 * one partition may impact the following partition.
-		 */
-		if (bdev_is_zoned(bdev) &&
-		    !part_zone_aligned(disk, bdev, from, size)) {
-			printk(KERN_WARNING
-			       "%s: p%d start %llu+%llu is not zone aligned\n",
-			       disk->disk_name, p, (unsigned long long) from,
-			       (unsigned long long) size);
-			continue;
-		}
-
 		part = add_partition(disk, p, from, size,
 				     state->parts[p].flags,
 				     &state->parts[p].info);
@@ -635,6 +578,7 @@ rescan:
 			md_autodetect_dev(part_to_dev(part)->devt);
 #endif
 	}
+out:
 	free_partitions(state);
 	return 0;
 }