block: Fix partition support for host aware zoned block devices

commit b53df2e7442c73a932fb74228147fb946e531585 upstream.

Commit b72053072c0b ("block: allow partitions on host aware zone
devices") introduced the helper function disk_has_partitions() to check
if a given disk has valid partitions. However, since this function result
directly depends on the disk partition table length rather than the
actual existence of valid partitions in the table, it returns true even
after all partitions are removed from the disk. For host aware zoned
block devices, this results in zone management support to be kept
disabled even after removing all partitions.

Fix this by changing disk_has_partitions() to walk through the partition
table entries and return true if and only if a valid non-zero size
partition is found.

Fixes: b72053072c0b ("block: allow partitions on host aware zone devices")
Cc: stable@vger.kernel.org # 5.5
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/block/genhd.c b/block/genhd.c
index ff6268970ddc069f84b3977069cca72ba10627c6..9c2e13ce0d19554a01eb72c03d5c0fcba7a67a5a 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -301,6 +301,42 @@ struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector)
 }
 EXPORT_SYMBOL_GPL(disk_map_sector_rcu);
 
+/**
+ * disk_has_partitions
+ * @disk: gendisk of interest
+ *
+ * Walk through the partition table and check if valid partition exists.
+ *
+ * CONTEXT:
+ * Don't care.
+ *
+ * RETURNS:
+ * True if the gendisk has at least one valid non-zero size partition.
+ * Otherwise false.
+ */
+bool disk_has_partitions(struct gendisk *disk)
+{
+       struct disk_part_tbl *ptbl;
+       int i;
+       bool ret = false;
+
+       rcu_read_lock();
+       ptbl = rcu_dereference(disk->part_tbl);
+
+       /* Iterate partitions skipping the whole device at index 0 */
+       for (i = 1; i < ptbl->len; i++) {
+               if (rcu_dereference(ptbl->part[i])) {
+                       ret = true;
+                       break;
+               }
+       }
+
+       rcu_read_unlock();
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(disk_has_partitions);
+
 /*
  * Can be deleted altogether. Later.
  *

diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index ea4c133b41397554dc336dcd62a85910a0a0d91a..0556153a9ad6c3d4b34e2ca340ed4d2d56894dac 100644 (file)
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -245,18 +245,6 @@ 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);
@@ -298,6 +286,7 @@ extern void disk_part_iter_exit(struct disk_part_iter *piter);
 
 extern struct hd_struct *disk_map_sector_rcu(struct gendisk *disk,
                                             sector_t sector);
+bool disk_has_partitions(struct gendisk *disk);
 
 /*
  * Macros to operate on percpu disk statistics: