Re: next-20260917 and next-20260918: merge of the block tree breaks all zoned devices

[Damien Le Moal <dlemoal@kernel.org>]

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On 9/21/26 09:49, Tao Cui wrote:
> Hi Mark, Damien,
> 
> 在 2026/9/21 06:37, Damien Le Moal 写道:
>> On 9/21/26 00:18, Mark Brown wrote:
>>> I did say when I did that merge that I had no confidence in it but
>>> nobody responded.  Can you please send me a commit on top of current
>>> -next which fixes up the resolution appropriately?  I can drop extra
>>> fixups in relatively easily, it's probably safer to take something that
>>> you have tested.
>>
>> Mark,
>>
>> My apologies for not replying, but I was traveling. I had looked at your
>> resolution but only quickly and I did not notice the incorrect comparison
>> causing the issue.
>>
>> I am attaching a diff that cleans up the conflict resolution.
>>
> 
> I tested Damien's patch on top of next-20260918.
> 
> It restores the zoned null_blk here: nullb0 is created again, reports
> host-managed, and the queue chunk size is back to 131072 sectors
> (CONFIG_BLK_DEV_NULL_BLK=y, "null_blk.zoned=1 null_blk.gb=1
> null_blk.zone_size=64" on the kernel command line).  So this looks
> good to me.
> 
> Tested-by: Tao Cui <cuitao@kylinos.cn>
> 
> One question for Damien while looking through the merged code: both
> parents had the power-of-two check for zone_sectors, but that check
> also disappears in the merged result.  Was that removal intentional,
> or should it be restored as well?

Mark, Attaching a v2 diff for corrected the conflict resolution. This is on top
of the current linux-next.

Thanks.


-- 
Damien Le Moal
Western Digital Research

[-- Attachment #2: v2-blk-zoned.diff --]
[-- Type: text/x-patch, Size: 1907 bytes --]

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index bae48f0d3464..19268afb8752 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -2031,11 +2031,16 @@ void disk_init_zone_resources(struct gendisk *disk)
 static unsigned int disk_get_nr_zones(struct gendisk *disk, sector_t capacity)
 {
 	struct queue_limits *lim = &disk->queue->limits;
+	unsigned long long nr_zones;
 
 	if (!capacity || !lim->chunk_sectors)
 		return 0;
 
-	return DIV_ROUND_UP_ULL(capacity, lim->chunk_sectors);
+	nr_zones = DIV_ROUND_UP_ULL(capacity, lim->chunk_sectors);
+	if (nr_zones > UINT_MAX)
+		return 0;
+
+	return nr_zones;
 }
 
 /*
@@ -2197,8 +2202,8 @@ static int disk_init_revalidate_args(struct gendisk *disk,
 {
 	args->disk = disk;
 	args->nr_zones = disk_get_nr_zones(disk, args->capacity);
-	if (args->nr_zones > UINT_MAX)
-		return -EINVAL;
+	if (!args->nr_zones)
+		return -ENODEV;
 
 	/* Cached zone conditions: 1 byte per zone */
 	args->zones_state = kzalloc(args->nr_zones, GFP_NOIO);
@@ -2322,15 +2327,22 @@ static void disk_drop_zone_wplug(struct blk_zone_wplug *zwplug, void *data)
 static int disk_revalidate_capacity(struct gendisk *disk,
 				    struct blk_revalidate_zone_args *args)
 {
+	struct queue_limits *lim = &disk->queue->limits;
+        sector_t zone_sectors = lim->chunk_sectors;
 	unsigned int nr_zones;
 	int ret = -ENODEV;
 
+	/* Checks that the device driver indicated a valid zone size. */
+	if (!zone_sectors || !is_power_of_2(zone_sectors)) {
+		pr_warn("%s: Invalid non power of two zone size (%llu)\n",
+			disk->disk_name, zone_sectors);
+		goto drop_all_zwplugs;
+	}
+
 	args->capacity = get_capacity(disk);
 	nr_zones = disk_get_nr_zones(disk, args->capacity);
 	if (!args->capacity || !nr_zones)
 		goto drop_all_zwplugs;
-	if (args->capacity >= args->nr_zones)
-		goto drop_all_zwplugs;
 
 	/*
 	 * Check if the capacity has changed. If it did, assume that the device