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From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>, Josef Bacik <josef@toxicpanda.com>,
	Minchan Kim <minchan@kernel.org>, Nitin Gupta <ngupta@vflare.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Jan Kara <jack@suse.cz>, "Darrick J . Wong" <djwong@kernel.org>,
	Ming Lei <ming.lei@redhat.com>,
	Matteo Croce <mcroce@microsoft.com>,
	linux-block@vger.kernel.org, nbd@other.debian.org
Subject: [PATCH 11/15] loop: implement ->free_disk
Date: Wed, 30 Mar 2022 07:29:13 +0200	[thread overview]
Message-ID: <20220330052917.2566582-12-hch@lst.de> (raw)
In-Reply-To: <20220330052917.2566582-1-hch@lst.de>

Ensure that the lo_device which is stored in the gendisk private
data is valid until the gendisk is freed.  Currently the loop driver
uses a lot of effort to make sure a device is not freed when it is
still in use, but to to fix a potential deadlock this will be relaxed
a bit soon.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 drivers/block/loop.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index a5dd259958ee2..b3170e8cdbe95 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1765,6 +1765,14 @@ static void lo_release(struct gendisk *disk, fmode_t mode)
 	mutex_unlock(&lo->lo_mutex);
 }
 
+static void lo_free_disk(struct gendisk *disk)
+{
+	struct loop_device *lo = disk->private_data;
+
+	mutex_destroy(&lo->lo_mutex);
+	kfree(lo);
+}
+
 static const struct block_device_operations lo_fops = {
 	.owner =	THIS_MODULE,
 	.open =		lo_open,
@@ -1773,6 +1781,7 @@ static const struct block_device_operations lo_fops = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl =	lo_compat_ioctl,
 #endif
+	.free_disk =	lo_free_disk,
 };
 
 /*
@@ -2064,15 +2073,14 @@ static void loop_remove(struct loop_device *lo)
 {
 	/* Make this loop device unreachable from pathname. */
 	del_gendisk(lo->lo_disk);
-	blk_cleanup_disk(lo->lo_disk);
+	blk_cleanup_queue(lo->lo_disk->queue);
 	blk_mq_free_tag_set(&lo->tag_set);
 
 	mutex_lock(&loop_ctl_mutex);
 	idr_remove(&loop_index_idr, lo->lo_number);
 	mutex_unlock(&loop_ctl_mutex);
-	/* There is no route which can find this loop device. */
-	mutex_destroy(&lo->lo_mutex);
-	kfree(lo);
+
+	put_disk(lo->lo_disk);
 }
 
 static void loop_probe(dev_t dev)
-- 
2.30.2


  parent reply	other threads:[~2022-03-30  5:30 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-30  5:29 yet another approach to fix the loop lock order inversions v6 Christoph Hellwig
2022-03-30  5:29 ` [PATCH 01/15] nbd: use the correct block_device in nbd_bdev_reset Christoph Hellwig
2022-04-18 12:54   ` Jens Axboe
2022-03-30  5:29 ` [PATCH 02/15] zram: cleanup reset_store Christoph Hellwig
2022-03-30  5:29 ` [PATCH 03/15] zram: cleanup zram_remove Christoph Hellwig
2022-03-30  5:29 ` [PATCH 04/15] block: add a disk_openers helper Christoph Hellwig
2022-03-30  5:29 ` [PATCH 05/15] block: turn bdev->bd_openers into an atomic_t Christoph Hellwig
2022-03-30  5:29 ` [PATCH 06/15] loop: de-duplicate the idle worker freeing code Christoph Hellwig
2022-03-30  5:29 ` [PATCH 07/15] loop: initialize the worker tracking fields once Christoph Hellwig
2022-03-30  5:29 ` [PATCH 08/15] loop: remove the racy bd_inode->i_mapping->nrpages asserts Christoph Hellwig
2022-03-30  5:29 ` [PATCH 09/15] loop: don't freeze the queue in lo_release Christoph Hellwig
2022-03-30  5:29 ` [PATCH 10/15] loop: only freeze the queue in __loop_clr_fd when needed Christoph Hellwig
2022-03-30  5:29 ` Christoph Hellwig [this message]
2022-03-30  5:29 ` [PATCH 12/15] loop: suppress uevents while reconfiguring the device Christoph Hellwig
2022-03-30  5:29 ` [PATCH 13/15] loop: avoid loop_validate_mutex/lo_mutex in ->release Christoph Hellwig
2022-03-30  5:29 ` [PATCH 14/15] loop: remove lo_refcount and avoid lo_mutex in ->open / ->release Christoph Hellwig
2022-03-30  5:29 ` [PATCH 15/15] loop: don't destroy lo->workqueue in __loop_clr_fd Christoph Hellwig
2022-04-04  7:42 ` yet another approach to fix the loop lock order inversions v6 Christoph Hellwig
2022-04-04  9:39   ` Tetsuo Handa
2022-04-05  6:28     ` Christoph Hellwig
2022-04-05  6:38       ` Tetsuo Handa
2022-04-05  9:10       ` Jan Kara
2022-04-18  9:39     ` Tetsuo Handa

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