5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Damien Le Moal <dlemoal@kernel.org>
commit 3f9c7a108c0e8f14425384912017071b71341e3b upstream.
Zoned block devices do not support partitions. However, the partition
table is nevertheless still inspected, and any partition found ignored
with a warning in add_partition(). While this is generally not a problem,
and in fact beneficial to the user as it indicates an invalid use of a
zoned block device, scanning for a partition table on the device may
result in issuing read operations to offline zones (e.g. after a disk head
is depopulated for disks that support head management operations).
Since partitions are ignored anyway, completely disable partition scanning
for zoned gendisks by setting the flag GENHD_FL_NO_PART in __add_disk().
The existing check in add_partition() is left as-is to ensure that we
still get a warning if for whatever reason, despite GENHD_FL_NO_PART, we
still endup trying to add partitions.
Flagging zoned disks with GENHD_FL_NO_PART also has the benefit to expose
through sysfs the ext_range attribute with the value of 1 instead of the
default DISK_MAX_PARTS, thus correctly advertizing the fact that zoned
disks do not support partitions.
Fixes: 5eac3eb30c9a ("block: Remove partition support for zoned block devices")
Cc: <redacted>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://patch.msgid.link/20260831025050.667758-1-dlemoal@kernel.org (local)
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
block/genhd.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -465,6 +465,13 @@ int device_add_disk(struct device *paren
}
/*
+ * We do not support partitions with zoned block devices, so do not try
+ * to scan the partitions table.
+ */
+ if (blk_queue_is_zoned(disk->queue))
+ disk->flags |= GENHD_FL_NO_PART;
+
+ /*
* avoid probable deadlock caused by allocating memory with
* GFP_KERNEL in runtime_resume callback of its all ancestor
* devices