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From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-bcache@vger.kernel.org, Jan Kara <jack@suse.cz>,
	linux-fsdevel@vger.kernel.org, Mike Snitzer <snitzer@redhat.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jan Kara <jack@suse.com>, Josef Bacik <josef@toxicpanda.com>,
	Coly Li <colyli@suse.de>,
	linux-block@vger.kernel.org, Richard Weinberger <richard@nod.at>,
	dm-devel@redhat.com, linux-mtd@lists.infradead.org,
	Johannes Thumshirn <johannes.thumshirn@wdc.com>,
	Tejun Heo <tj@kernel.org>,
	xen-devel@lists.xenproject.org, linux-mm@kvack.org
Subject: [dm-devel] [PATCH 06/45] zram: remove the claim mechanism
Date: Tue, 24 Nov 2020 14:27:12 +0100	[thread overview]
Message-ID: <20201124132751.3747337-7-hch@lst.de> (raw)
In-Reply-To: <20201124132751.3747337-1-hch@lst.de>

The zram claim mechanism was added to ensure no new opens come in
during teardown.  But the proper way to archive that is to call
del_gendisk first, which takes care of all that.  Once del_gendisk
is called in the right place, the reset side can also be simplified
as no I/O can be outstanding on a block device that is not open.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/zram/zram_drv.c | 72 ++++++++---------------------------
 1 file changed, 15 insertions(+), 57 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 6d15d51cee2b7e..2e6d75ec1afddb 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1756,64 +1756,33 @@ static ssize_t disksize_store(struct device *dev,
 static ssize_t reset_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
-	int ret;
-	unsigned short do_reset;
-	struct zram *zram;
+	struct zram *zram = dev_to_zram(dev);
 	struct block_device *bdev;
+	unsigned short do_reset;
+	int ret = 0;
 
 	ret = kstrtou16(buf, 10, &do_reset);
 	if (ret)
 		return ret;
-
 	if (!do_reset)
 		return -EINVAL;
 
-	zram = dev_to_zram(dev);
 	bdev = bdget_disk(zram->disk, 0);
 	if (!bdev)
 		return -ENOMEM;
 
 	mutex_lock(&bdev->bd_mutex);
-	/* Do not reset an active device or claimed device */
-	if (bdev->bd_openers || zram->claim) {
-		mutex_unlock(&bdev->bd_mutex);
-		bdput(bdev);
-		return -EBUSY;
-	}
-
-	/* From now on, anyone can't open /dev/zram[0-9] */
-	zram->claim = true;
+	if (bdev->bd_openers)
+		ret = -EBUSY;
+	else
+		zram_reset_device(zram);
 	mutex_unlock(&bdev->bd_mutex);
-
-	/* Make sure all the pending I/O are finished */
-	fsync_bdev(bdev);
-	zram_reset_device(zram);
 	bdput(bdev);
 
-	mutex_lock(&bdev->bd_mutex);
-	zram->claim = false;
-	mutex_unlock(&bdev->bd_mutex);
-
-	return len;
-}
-
-static int zram_open(struct block_device *bdev, fmode_t mode)
-{
-	int ret = 0;
-	struct zram *zram;
-
-	WARN_ON(!mutex_is_locked(&bdev->bd_mutex));
-
-	zram = bdev->bd_disk->private_data;
-	/* zram was claimed to reset so open request fails */
-	if (zram->claim)
-		ret = -EBUSY;
-
-	return ret;
+	return ret ? ret : len;
 }
 
 static const struct block_device_operations zram_devops = {
-	.open = zram_open,
 	.submit_bio = zram_submit_bio,
 	.swap_slot_free_notify = zram_slot_free_notify,
 	.rw_page = zram_rw_page,
@@ -1821,7 +1790,6 @@ static const struct block_device_operations zram_devops = {
 };
 
 static const struct block_device_operations zram_wb_devops = {
-	.open = zram_open,
 	.submit_bio = zram_submit_bio,
 	.swap_slot_free_notify = zram_slot_free_notify,
 	.owner = THIS_MODULE
@@ -1974,32 +1942,22 @@ static int zram_add(void)
 
 static int zram_remove(struct zram *zram)
 {
-	struct block_device *bdev;
-
-	bdev = bdget_disk(zram->disk, 0);
-	if (!bdev)
-		return -ENOMEM;
+	struct block_device *bdev = bdget_disk(zram->disk, 0);
 
-	mutex_lock(&bdev->bd_mutex);
-	if (bdev->bd_openers || zram->claim) {
-		mutex_unlock(&bdev->bd_mutex);
+	if (bdev) {
+		if (bdev->bd_openers) {
+			bdput(bdev);
+			return -EBUSY;
+		}
 		bdput(bdev);
-		return -EBUSY;
 	}
 
-	zram->claim = true;
-	mutex_unlock(&bdev->bd_mutex);
-
+	del_gendisk(zram->disk);
 	zram_debugfs_unregister(zram);
-
-	/* Make sure all the pending I/O are finished */
-	fsync_bdev(bdev);
 	zram_reset_device(zram);
-	bdput(bdev);
 
 	pr_info("Removed device: %s\n", zram->disk->disk_name);
 
-	del_gendisk(zram->disk);
 	blk_cleanup_queue(zram->disk->queue);
 	put_disk(zram->disk);
 	kfree(zram);
-- 
2.29.2

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  parent reply	other threads:[~2020-11-24 13:32 UTC|newest]

Thread overview: 90+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-24 13:27 [dm-devel] merge struct block_device and struct hd_struct v2 Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 01/45] blk-cgroup: fix a hd_struct leak in blkcg_fill_root_iostats Christoph Hellwig
2020-11-25  6:41   ` Hannes Reinecke
2020-11-24 13:27 ` [dm-devel] [PATCH 02/45] filemap: consistently use ->f_mapping over ->i_mapping Christoph Hellwig
2020-11-24 13:53   ` Matthew Wilcox
2020-11-25  6:41   ` Hannes Reinecke
2020-11-25 12:16   ` Jan Kara
2020-11-24 13:27 ` [dm-devel] [PATCH 03/45] fs: remove get_super_thawed and get_super_exclusive_thawed Christoph Hellwig
2020-11-25  6:42   ` Hannes Reinecke
2020-11-25 12:19   ` Jan Kara
2020-11-24 13:27 ` [dm-devel] [PATCH 04/45] fs: simplify freeze_bdev/thaw_bdev Christoph Hellwig
2020-11-25  6:07   ` Chao Yu
2020-11-25 12:29   ` Jan Kara
2020-11-25 16:22     ` Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 05/45] mtip32xx: remove the call to fsync_bdev on removal Christoph Hellwig
2020-11-25 12:31   ` Jan Kara
2020-11-24 13:27 ` Christoph Hellwig [this message]
2020-11-25 12:37   ` [dm-devel] [PATCH 06/45] zram: remove the claim mechanism Jan Kara
2020-11-24 13:27 ` [dm-devel] [PATCH 07/45] zram: do not call set_blocksize Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 08/45] loop: " Christoph Hellwig
2020-11-25 13:37   ` Jan Kara
2020-11-24 13:27 ` [dm-devel] [PATCH 09/45] dm: simplify flush_bio initialization in __send_empty_flush Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 10/45] dm: remove the block_device reference in struct mapped_device Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 11/45] block: remove a duplicate __disk_get_part prototype Christoph Hellwig
2020-11-24 17:36   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 12/45] block: remove a superflous check in blkpg_do_ioctl Christoph Hellwig
2020-11-24 17:37   ` Tejun Heo
2020-11-25 13:39   ` Jan Kara
2020-11-24 13:27 ` [dm-devel] [PATCH 13/45] block: add a bdev_kobj helper Christoph Hellwig
2020-11-24 13:41   ` Coly Li
2020-11-24 17:37   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 14/45] block: use disk_part_iter_exit in disk_part_iter_next Christoph Hellwig
2020-11-24 17:37   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 15/45] block: use put_device in put_disk Christoph Hellwig
2020-11-24 17:37   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 16/45] block: change the hash used for looking up block devices Christoph Hellwig
2020-11-24 17:38   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 17/45] init: refactor name_to_dev_t Christoph Hellwig
2020-11-24 17:38   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 18/45] init: refactor devt_from_partuuid Christoph Hellwig
2020-11-24 17:38   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 19/45] init: cleanup match_dev_by_uuid and match_dev_by_label Christoph Hellwig
2020-11-24 17:39   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 20/45] block: refactor __blkdev_put Christoph Hellwig
2020-11-24 17:41   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 21/45] block: refactor blkdev_get Christoph Hellwig
2020-11-24 18:03   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 22/45] block: opencode devcgroup_inode_permission Christoph Hellwig
2020-11-24 18:05   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 23/45] block: remove i_bdev Christoph Hellwig
2020-11-24 13:38   ` Coly Li
2020-11-24 19:37   ` Tejun Heo
2020-11-25 16:29     ` Christoph Hellwig
2020-11-25 20:19       ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 24/45] blk-cgroup: stop abusing get_gendisk Christoph Hellwig
2020-11-24 19:46   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 25/45] block: reference struct block_device from struct hd_struct Christoph Hellwig
2020-11-24 21:18   ` Tejun Heo
2020-11-25 16:45     ` Christoph Hellwig
2020-11-25 20:20       ` Tejun Heo
2020-11-26  8:16         ` Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 26/45] block: remove ->bd_contains Christoph Hellwig
2020-11-24 21:19   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 27/45] block: simplify the block device claiming interface Christoph Hellwig
2020-11-24 21:19   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 28/45] block: simplify part_to_disk Christoph Hellwig
2020-11-24 21:20   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 29/45] block: initialize struct block_device in bdev_alloc Christoph Hellwig
2020-11-24 21:20   ` Tejun Heo
2020-11-24 13:27 ` [dm-devel] [PATCH 30/45] block: remove the nr_sects field in struct hd_struct Christoph Hellwig
2020-11-24 13:34   ` Coly Li
2020-11-25  6:10   ` Chao Yu
2020-11-24 13:27 ` [dm-devel] [PATCH 31/45] block: move disk stat accounting to struct block_device Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 32/45] block: move the start_sect field " Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 33/45] block: move the partition_meta_info " Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 34/45] block: move holder_dir " Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 35/45] block: move make_it_fail " Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 36/45] block: move the policy field " Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 37/45] block: allocate struct hd_struct as part of struct bdev_inode Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 38/45] block: switch partition lookup to use struct block_device Christoph Hellwig
2020-11-24 13:32   ` Coly Li
2020-11-25  6:11   ` Chao Yu
2020-11-24 13:27 ` [dm-devel] [PATCH 39/45] block: remove the partno field from struct hd_struct Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 40/45] block: pass a block_device to blk_alloc_devt Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 41/45] block: pass a block_device to invalidate_partition Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 42/45] block: switch disk_part_iter_* to use a struct block_device Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 43/45] f2fs: remove a few bd_part checks Christoph Hellwig
2020-11-25  6:12   ` Chao Yu
2020-11-24 13:27 ` [dm-devel] [PATCH 44/45] block: merge struct block_device and struct hd_struct Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 45/45] block: stop using bdget_disk for partition 0 Christoph Hellwig

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