From: Jan Kara <jack@suse.cz>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>, 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-bcache@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [dm-devel] [PATCH 06/45] zram: remove the claim mechanism
Date: Wed, 25 Nov 2020 13:37:50 +0100 [thread overview]
Message-ID: <20201125123750.GJ16944@quack2.suse.cz> (raw)
In-Reply-To: <20201124132751.3747337-7-hch@lst.de>
On Tue 24-11-20 14:27:12, Christoph Hellwig wrote:
> 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
^^^ achieve
> 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>
Otherwise I didn't find anything obviously wrong with the patch but I don't
feel confident enough with zram to really give you my reviewed-by on this
one.
Honza
> ---
> 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
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
--
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next prev parent reply other threads:[~2020-11-25 15:20 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 ` [dm-devel] [PATCH 06/45] zram: remove the claim mechanism Christoph Hellwig
2020-11-25 12:37 ` Jan Kara [this message]
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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