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charset="utf-8" Message-Id: <20261022-b4-loop-nbd-stale-partitions-v3-2-7c58ecab69c8@amutable.com> References: <20261022-b4-loop-nbd-stale-partitions-v3-0-7c58ecab69c8@amutable.com> In-Reply-To: <20261022-b4-loop-nbd-stale-partitions-v3-0-7c58ecab69c8@amutable.com> To: Jens Axboe , Christian Brauner , Josef Bacik , Daan De Meyer Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, nbd@other.debian.org, Christoph Hellwig , Bart Van Assche , Shin'ichiro Kawasaki , Daan De Meyer , stable@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1792675886; l=2227; i=daan@amutable.com; s=20260712; h=from:subject:message-id; bh=IJsYukTCp+gKDcCUl73TRLZtzYPIPmGwnx1/NOZHD4E=; b=SDLMBKjcSDyBAiGNS/QgWYnRmKqNgOs/BmSlZQTKdlkMwZqJHCosTH83xBE6ud2910pRQi4Vw UHqCmIIWiHOBf++I5GWOGa8g8zFBOEVxwdKFP0RlMhfUVdpid2D02vt X-Developer-Key: i=daan@amutable.com; a=ed25519; pk=I1l+WwrtmzRgofA5SQ1wTuJi18fjh91w+f5uRkFeZEA= X-Endpoint-Received: by B4 Relay for daan@amutable.com/20260712 with auth_id=868 X-Original-From: Daan De Meyer Reply-To: daan@amutable.com Content-Transfer-Encoding: 7bit From: Daan De Meyer Commit 267ec4d7223a ("loop: fix partition scan race between udev and loop_reread_partitions()") stopped disk_force_media_change() from setting GD_NEED_PART_SCAN. Besides requesting a rescan, that bit was what removed stale partitions on the next open, as bdev_disk_changed() drops all partitions before it consults disk_has_partscan(). nbd_clear_sock_ioctl() relied on that. It zeroes the capacity through nbd_bdev_reset(), but nothing removes the partitions of the disconnected device anymore. With the default max_part=16 they linger until the next connect sets GD_NEED_PART_SCAN again. With max_part=0 nothing ever sets it, so they are never removed at all, even though nbd does not set GENHD_FL_NO_PART and partitions can therefore still be added with BLKPG. Set GD_NEED_PART_SCAN in nbd_clear_sock_ioctl() so the partitions are dropped on the next open. Calling bdev_disk_changed() directly is not an option as it needs open_mutex, which nbd_open() acquires under config_lock. Fixes: 267ec4d7223a ("loop: fix partition scan race between udev and loop_reread_partitions()") Cc: stable@vger.kernel.org Reviewed-by: Christian Brauner (Amutable) Reviewed-by: Bart Van Assche Tested-by: Shin'ichiro Kawasaki Signed-off-by: Daan De Meyer --- drivers/block/nbd.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index ffce519bf008..09b4ad70a5d7 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1616,6 +1616,13 @@ static void nbd_clear_sock_ioctl(struct nbd_device *nbd) nbd_clear_sock(nbd); disk_force_media_change(nbd->disk); nbd_bdev_reset(nbd); + /* + * Drop the partitions of the disconnected device on the next open. + * They can exist even with max_part zero as they may have been added + * manually with BLKPG. Dropping them here is not possible as that + * needs open_mutex, which nbd_open() acquires under config_lock. + */ + set_bit(GD_NEED_PART_SCAN, &nbd->disk->state); if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF, &nbd->config->runtime_flags)) nbd_config_put(nbd); -- 2.54.0