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From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Jan Kara <jack@suse.cz>,
	linux-block@vger.kernel.org, Ming Lei <ming.lei@redhat.com>,
	"Darrick J . Wong" <djwong@kernel.org>
Subject: [PATCH 7/8] loop: only freeze the queue in __loop_clr_fd when needed
Date: Fri, 28 Jan 2022 14:00:21 +0100	[thread overview]
Message-ID: <20220128130022.1750906-8-hch@lst.de> (raw)
In-Reply-To: <20220128130022.1750906-1-hch@lst.de>

->release is only called after all outstanding I/O has completed, so only
freeze the queue when clearing the backing file of a live loop device.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Tested-by: Darrick J. Wong <djwong@kernel.org>
---
 drivers/block/loop.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 1ca70f735b5bc..0cdbc60037642 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1110,7 +1110,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
 	return error;
 }
 
-static void __loop_clr_fd(struct loop_device *lo)
+static void __loop_clr_fd(struct loop_device *lo, bool release)
 {
 	struct file *filp;
 	gfp_t gfp = lo->old_gfp_mask;
@@ -1139,8 +1139,13 @@ static void __loop_clr_fd(struct loop_device *lo)
 	if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags))
 		blk_queue_write_cache(lo->lo_queue, false, false);
 
-	/* freeze request queue during the transition */
-	blk_mq_freeze_queue(lo->lo_queue);
+	/*
+	 * Freeze the request queue when unbinding on a live file descriptor and
+	 * thus an open device.  When called from ->release we are guaranteed
+	 * that there is no I/O in progress already.
+	 */
+	if (!release)
+		blk_mq_freeze_queue(lo->lo_queue);
 
 	destroy_workqueue(lo->workqueue);
 	loop_free_idle_workers(lo, true);
@@ -1163,7 +1168,8 @@ static void __loop_clr_fd(struct loop_device *lo)
 	/* let user-space know about this change */
 	kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
 	mapping_set_gfp_mask(filp->f_mapping, gfp);
-	blk_mq_unfreeze_queue(lo->lo_queue);
+	if (!release)
+		blk_mq_unfreeze_queue(lo->lo_queue);
 
 	disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
 
@@ -1201,7 +1207,7 @@ static void loop_rundown_workfn(struct work_struct *work)
 	struct block_device *bdev = lo->lo_device;
 	struct gendisk *disk = lo->lo_disk;
 
-	__loop_clr_fd(lo);
+	__loop_clr_fd(lo, true);
 	kobject_put(&bdev->bd_device.kobj);
 	module_put(disk->fops->owner);
 	loop_rundown_completed(lo);
@@ -1247,7 +1253,7 @@ static int loop_clr_fd(struct loop_device *lo)
 	lo->lo_state = Lo_rundown;
 	mutex_unlock(&lo->lo_mutex);
 
-	__loop_clr_fd(lo);
+	__loop_clr_fd(lo, false);
 	loop_rundown_completed(lo);
 	return 0;
 }
-- 
2.30.2


  parent reply	other threads:[~2022-01-28 13:00 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-28 13:00 yet another approach to fix loop autoclear for xfstets xfs/049 v2 Christoph Hellwig
2022-01-28 13:00 ` [PATCH 1/8] loop: de-duplicate the idle worker freeing code Christoph Hellwig
2022-01-28 13:00 ` [PATCH 2/8] loop: initialize the worker tracking fields once Christoph Hellwig
2022-01-28 13:00 ` [PATCH 3/8] loop: remove the racy bd_inode->i_mapping->nrpages asserts Christoph Hellwig
2022-01-28 13:36   ` Jan Kara
2022-01-28 13:00 ` [PATCH 4/8] loop: only take lo_mutex for the last reference in lo_release Christoph Hellwig
2022-01-28 13:37   ` Jan Kara
2022-01-28 13:00 ` [PATCH 5/8] loop: only take lo_mutex for the first reference in lo_open Christoph Hellwig
2022-01-28 13:13   ` Tetsuo Handa
2022-02-05  0:28     ` Tetsuo Handa
2022-02-06  7:10       ` Tetsuo Handa
2022-02-08 13:45       ` Jan Kara
2022-02-23 14:24         ` Tetsuo Handa
2022-01-28 13:38   ` Jan Kara
2022-01-28 13:00 ` [PATCH 6/8] loop: don't freeze the queue in lo_release Christoph Hellwig
2022-01-28 13:00 ` Christoph Hellwig [this message]
2022-01-28 13:00 ` [PATCH 8/8] loop: make autoclear operation synchronous again Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2022-01-26 15:50 yet another approach to fix loop autoclear for xfstets xfs/049 Christoph Hellwig
2022-01-26 15:50 ` [PATCH 7/8] loop: only freeze the queue in __loop_clr_fd when needed Christoph Hellwig
2022-01-27 11:01   ` Jan Kara
2022-01-28  6:48     ` Christoph Hellwig

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