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Mon, 19 Oct 2026 18:23:13 -0700 (PDT) Received: from [192.168.1.106] ([198.8.77.135]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-849859184easm3988307a34.23.2026.10.19.18.23.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Oct 2026 18:23:13 -0700 (PDT) Message-ID: <3ede4588-ffac-42ec-8058-b37c241b6830@kernel.dk> Date: Mon, 19 Oct 2026 19:23:12 -0600 X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/2] loop, nbd: drop partitions left behind by the GD_NEED_PART_SCAN removal To: Cyril Brulebois , daan@amutable.com Cc: Christian Brauner , Josef Bacik , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, nbd@other.debian.org, Christoph Hellwig , Bart Van Assche , Shin'ichiro Kawasaki , stable@vger.kernel.org References: <20260824-b4-loop-nbd-stale-partitions-v2-0-9815a577cebd@amutable.com> <20261019233109.55q3cd266dfmkpa2@mraw.org> Content-Language: en-US From: Jens Axboe In-Reply-To: <20261019233109.55q3cd266dfmkpa2@mraw.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/19/26 5:31 PM, Cyril Brulebois wrote: > Hi, > > Daan De Meyer via B4 Relay (2026-08-24): >> Commit 267ec4d7223a ("loop: fix partition scan race between udev and >> loop_reread_partitions()") stopped disk_force_media_change() from setting >> GD_NEED_PART_SCAN. The caller audit in that commit only considered the bit >> as a request to rescan partitions, but it did more than that: >> bdev_disk_changed() drops every entry in disk->part_tbl before it consults >> disk_has_partscan(), and only the re-adding half is gated on partition >> scanning being enabled. The lazy scan on the next open was therefore also >> the only thing removing partitions from a device that has partitions but >> no partition scanning. >> >> Loop devices without LO_FLAGS_PARTSCAN are exactly such devices, and they >> are not unusual. bdev_add_partition() only rejects GENHD_FL_NO_PART disks, >> so BLKPG_ADD_PARTITION works while GD_SUPPRESS_PART_SCAN is set, and >> parted, libfdisk and systemd all fall back to BLKPG when BLKRRPART fails >> with -EINVAL, which is what a loop device without LO_FLAGS_PARTSCAN >> returns. >> >> Commit c4f4c0fc551c ("loop: remove manually added partitions on detach") >> fixed the detach path after this was reported as loop devices picking up >> partition devices from a previously built image: >> >> https://bugs.debian.org/1141434 >> >> These two patches fix the two remaining places that relied on the same >> lazy cleanup, LOOP_CHANGE_FD and NBD_CLEAR_SOCK. >> >> Regression tests for both paths have been submitted to blktests: >> >> https://github.com/linux-blktests/blktests/pull/259 >> https://github.com/linux-blktests/blktests/pull/260 >> >> Signed-off-by: Daan De Meyer >> --- >> Changes in v2: >> - Rewrap the comments added by both patches so they fit in 80 columns >> (Christoph Hellwig). >> - No functional change, so the review and test tags from v1 were carried >> over. >> - Link to v1: https://patch.msgid.link/20260806-b4-loop-nbd-stale-partitions-v1-0-67bb75a8d7be@amutable.com > > It would be nice if those fixes could get picked up eventually. They > received a few Reviewed-by and Tested-by already, and that v2 is only > about line wrapping anyway. They need a respin. -- Jens Axboe