linux-kernel - [PATCH] nbd: Respect max_part for all partition scans

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Message-ID: <86d03378210ddac44eb07ebb78c9b0f32c56fe96.1608195087.git.josh@joshtriplett.org>
Date:   Thu, 17 Dec 2020 00:58:47 -0800
From:   Josh Triplett <josh@...htriplett.org>
To:     Josef Bacik <josef@...icpanda.com>, Jens Axboe <axboe@...nel.dk>
Cc:     linux-block@...r.kernel.org, nbd@...er.debian.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] nbd: Respect max_part for all partition scans

The creation path of the NBD device respects max_part and only scans for
partitions if max_part is not 0. However, some other code paths ignore
max_part, and unconditionally scan for partitions. Add a check for
max_part on each partition scan.

Signed-off-by: Josh Triplett <josh@...htriplett.org>
---

Caught this when reading recent NBD patches, which tweaked the
nbd_set_size path.

It doesn't seem worth factoring these two lines into a function,
especially since the callers obtain the disk structure in different
ways.

 drivers/block/nbd.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 92f84ed0ba9e..6727358e147d 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -318,7 +318,8 @@ static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
 	blk_queue_logical_block_size(nbd->disk->queue, blksize);
 	blk_queue_physical_block_size(nbd->disk->queue, blksize);
 
-	set_bit(GD_NEED_PART_SCAN, &nbd->disk->state);
+	if (max_part)
+		set_bit(GD_NEED_PART_SCAN, &nbd->disk->state);
 	if (!set_capacity_and_notify(nbd->disk, bytesize >> 9))
 		kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 	return 0;
@@ -1476,9 +1477,11 @@ static int nbd_open(struct block_device *bdev, fmode_t mode)
 		refcount_set(&nbd->config_refs, 1);
 		refcount_inc(&nbd->refs);
 		mutex_unlock(&nbd->config_lock);
-		set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
+		if (max_part)
+			set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
 	} else if (nbd_disconnected(nbd->config)) {
-		set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
+		if (max_part)
+			set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
 	}
 out:
 	mutex_unlock(&nbd_index_mutex);
-- 
2.29.2