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From: Jan Kara <jack@suse.cz>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>, Chao Yu <yuchao0@huawei.com>,
	Jan Kara <jack@suse.cz>, Mike Snitzer <snitzer@redhat.com>,
	linux-mm@kvack.org,
	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, linux-fsdevel@vger.kernel.org,
	dm-devel@redhat.com, linux-mtd@lists.infradead.org,
	Johannes Thumshirn <johannes.thumshirn@wdc.com>,
	Tejun Heo <tj@kernel.org>,
	linux-bcache@vger.kernel.org
Subject: Re: [dm-devel] [PATCH 04/44] fs: simplify freeze_bdev/thaw_bdev
Date: Thu, 26 Nov 2020 15:13:01 +0100
Message-ID: <20201126141301.GF422@quack2.suse.cz> (raw)
In-Reply-To: <20201126130422.92945-5-hch@lst.de>

On Thu 26-11-20 14:03:42, Christoph Hellwig wrote:
> Store the frozen superblock in struct block_device to avoid the awkward
> interface that can return a sb only used a cookie, an ERR_PTR or NULL.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Acked-by: Chao Yu <yuchao0@huawei.com>		[f2fs]

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  drivers/md/dm-core.h      |  5 -----
>  drivers/md/dm.c           | 20 ++++++--------------
>  fs/block_dev.c            | 37 +++++++++++++++----------------------
>  fs/buffer.c               |  2 +-
>  fs/ext4/ioctl.c           |  2 +-
>  fs/f2fs/file.c            | 14 +++++---------
>  fs/xfs/xfs_fsops.c        |  7 ++-----
>  include/linux/blk_types.h |  1 +
>  include/linux/blkdev.h    |  4 ++--
>  9 files changed, 33 insertions(+), 59 deletions(-)
> 
> diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
> index d522093cb39dda..aace147effcacb 100644
> --- a/drivers/md/dm-core.h
> +++ b/drivers/md/dm-core.h
> @@ -96,11 +96,6 @@ struct mapped_device {
>  	 */
>  	struct workqueue_struct *wq;
>  
> -	/*
> -	 * freeze/thaw support require holding onto a super block
> -	 */
> -	struct super_block *frozen_sb;
> -
>  	/* forced geometry settings */
>  	struct hd_geometry geometry;
>  
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 54739f1b579bc8..50541d336c719b 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -2392,27 +2392,19 @@ static int lock_fs(struct mapped_device *md)
>  {
>  	int r;
>  
> -	WARN_ON(md->frozen_sb);
> +	WARN_ON(test_bit(DMF_FROZEN, &md->flags));
>  
> -	md->frozen_sb = freeze_bdev(md->bdev);
> -	if (IS_ERR(md->frozen_sb)) {
> -		r = PTR_ERR(md->frozen_sb);
> -		md->frozen_sb = NULL;
> -		return r;
> -	}
> -
> -	set_bit(DMF_FROZEN, &md->flags);
> -
> -	return 0;
> +	r = freeze_bdev(md->bdev);
> +	if (!r)
> +		set_bit(DMF_FROZEN, &md->flags);
> +	return r;
>  }
>  
>  static void unlock_fs(struct mapped_device *md)
>  {
>  	if (!test_bit(DMF_FROZEN, &md->flags))
>  		return;
> -
> -	thaw_bdev(md->bdev, md->frozen_sb);
> -	md->frozen_sb = NULL;
> +	thaw_bdev(md->bdev);
>  	clear_bit(DMF_FROZEN, &md->flags);
>  }
>  
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index d8664f5c1ff669..33c29106c98907 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -548,55 +548,47 @@ EXPORT_SYMBOL(fsync_bdev);
>   * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
>   * actually.
>   */
> -struct super_block *freeze_bdev(struct block_device *bdev)
> +int freeze_bdev(struct block_device *bdev)
>  {
>  	struct super_block *sb;
>  	int error = 0;
>  
>  	mutex_lock(&bdev->bd_fsfreeze_mutex);
> -	if (++bdev->bd_fsfreeze_count > 1) {
> -		/*
> -		 * We don't even need to grab a reference - the first call
> -		 * to freeze_bdev grab an active reference and only the last
> -		 * thaw_bdev drops it.
> -		 */
> -		sb = get_super(bdev);
> -		if (sb)
> -			drop_super(sb);
> -		mutex_unlock(&bdev->bd_fsfreeze_mutex);
> -		return sb;
> -	}
> +	if (++bdev->bd_fsfreeze_count > 1)
> +		goto done;
>  
>  	sb = get_active_super(bdev);
>  	if (!sb)
> -		goto out;
> +		goto sync;
>  	if (sb->s_op->freeze_super)
>  		error = sb->s_op->freeze_super(sb);
>  	else
>  		error = freeze_super(sb);
> +	deactivate_super(sb);
> +
>  	if (error) {
> -		deactivate_super(sb);
>  		bdev->bd_fsfreeze_count--;
> -		mutex_unlock(&bdev->bd_fsfreeze_mutex);
> -		return ERR_PTR(error);
> +		goto done;
>  	}
> -	deactivate_super(sb);
> - out:
> +	bdev->bd_fsfreeze_sb = sb;
> +
> +sync:
>  	sync_blockdev(bdev);
> +done:
>  	mutex_unlock(&bdev->bd_fsfreeze_mutex);
> -	return sb;	/* thaw_bdev releases s->s_umount */
> +	return error;
>  }
>  EXPORT_SYMBOL(freeze_bdev);
>  
>  /**
>   * thaw_bdev  -- unlock filesystem
>   * @bdev:	blockdevice to unlock
> - * @sb:		associated superblock
>   *
>   * Unlocks the filesystem and marks it writeable again after freeze_bdev().
>   */
> -int thaw_bdev(struct block_device *bdev, struct super_block *sb)
> +int thaw_bdev(struct block_device *bdev)
>  {
> +	struct super_block *sb;
>  	int error = -EINVAL;
>  
>  	mutex_lock(&bdev->bd_fsfreeze_mutex);
> @@ -607,6 +599,7 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb)
>  	if (--bdev->bd_fsfreeze_count > 0)
>  		goto out;
>  
> +	sb = bdev->bd_fsfreeze_sb;
>  	if (!sb)
>  		goto out;
>  
> diff --git a/fs/buffer.c b/fs/buffer.c
> index 23f645657488ba..a7595ada9400ff 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -523,7 +523,7 @@ static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
>  
>  void emergency_thaw_bdev(struct super_block *sb)
>  {
> -	while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb))
> +	while (sb->s_bdev && !thaw_bdev(sb->s_bdev))
>  		printk(KERN_WARNING "Emergency Thaw on %pg\n", sb->s_bdev);
>  }
>  
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index f0381876a7e5b0..524e134324475e 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -624,7 +624,7 @@ static int ext4_shutdown(struct super_block *sb, unsigned long arg)
>  	case EXT4_GOING_FLAGS_DEFAULT:
>  		freeze_bdev(sb->s_bdev);
>  		set_bit(EXT4_FLAGS_SHUTDOWN, &sbi->s_ext4_flags);
> -		thaw_bdev(sb->s_bdev, sb);
> +		thaw_bdev(sb->s_bdev);
>  		break;
>  	case EXT4_GOING_FLAGS_LOGFLUSH:
>  		set_bit(EXT4_FLAGS_SHUTDOWN, &sbi->s_ext4_flags);
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index ee861c6d9ff026..a9fc482a0e60a5 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -2230,16 +2230,12 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
>  
>  	switch (in) {
>  	case F2FS_GOING_DOWN_FULLSYNC:
> -		sb = freeze_bdev(sb->s_bdev);
> -		if (IS_ERR(sb)) {
> -			ret = PTR_ERR(sb);
> +		ret = freeze_bdev(sb->s_bdev);
> +		if (ret)
>  			goto out;
> -		}
> -		if (sb) {
> -			f2fs_stop_checkpoint(sbi, false);
> -			set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
> -			thaw_bdev(sb->s_bdev, sb);
> -		}
> +		f2fs_stop_checkpoint(sbi, false);
> +		set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
> +		thaw_bdev(sb->s_bdev);
>  		break;
>  	case F2FS_GOING_DOWN_METASYNC:
>  		/* do checkpoint only */
> diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
> index ef1d5bb88b93ab..b7c5783a031c69 100644
> --- a/fs/xfs/xfs_fsops.c
> +++ b/fs/xfs/xfs_fsops.c
> @@ -433,13 +433,10 @@ xfs_fs_goingdown(
>  {
>  	switch (inflags) {
>  	case XFS_FSOP_GOING_FLAGS_DEFAULT: {
> -		struct super_block *sb = freeze_bdev(mp->m_super->s_bdev);
> -
> -		if (sb && !IS_ERR(sb)) {
> +		if (!freeze_bdev(mp->m_super->s_bdev)) {
>  			xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
> -			thaw_bdev(sb->s_bdev, sb);
> +			thaw_bdev(mp->m_super->s_bdev);
>  		}
> -
>  		break;
>  	}
>  	case XFS_FSOP_GOING_FLAGS_LOGFLUSH:
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index d9b69bbde5cc54..ebfb4e7c1fd125 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -46,6 +46,7 @@ struct block_device {
>  	int			bd_fsfreeze_count;
>  	/* Mutex for freeze */
>  	struct mutex		bd_fsfreeze_mutex;
> +	struct super_block	*bd_fsfreeze_sb;
>  } __randomize_layout;
>  
>  /*
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 05b346a68c2eee..12810a19edebc4 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -2020,7 +2020,7 @@ static inline int sync_blockdev(struct block_device *bdev)
>  #endif
>  int fsync_bdev(struct block_device *bdev);
>  
> -struct super_block *freeze_bdev(struct block_device *bdev);
> -int thaw_bdev(struct block_device *bdev, struct super_block *sb);
> +int freeze_bdev(struct block_device *bdev);
> +int thaw_bdev(struct block_device *bdev);
>  
>  #endif /* _LINUX_BLKDEV_H */
> -- 
> 2.29.2
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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  reply index

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-26 13:03 [dm-devel] merge struct block_device and struct hd_struct v3 Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 01/44] blk-cgroup: fix a hd_struct leak in blkcg_fill_root_iostats Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 02/44] filemap: consistently use ->f_mapping over ->i_mapping Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 03/44] fs: remove get_super_thawed and get_super_exclusive_thawed Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 04/44] fs: simplify freeze_bdev/thaw_bdev Christoph Hellwig
2020-11-26 14:13   ` Jan Kara [this message]
2020-11-26 13:03 ` [dm-devel] [PATCH 05/44] mtip32xx: remove the call to fsync_bdev on removal Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 06/44] zram: do not call set_blocksize Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 07/44] loop: " Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 08/44] dm: simplify flush_bio initialization in __send_empty_flush Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 09/44] dm: remove the block_device reference in struct mapped_device Christoph Hellwig
2020-11-27 10:36   ` Hannes Reinecke
2020-11-26 13:03 ` [dm-devel] [PATCH 10/44] block: remove a duplicate __disk_get_part prototype Christoph Hellwig
2020-11-27 10:36   ` Hannes Reinecke
2020-11-26 13:03 ` [dm-devel] [PATCH 11/44] block: remove a superflous check in blkpg_do_ioctl Christoph Hellwig
2020-11-27 10:37   ` Hannes Reinecke
2020-11-26 13:03 ` [dm-devel] [PATCH 12/44] block: add a bdev_kobj helper Christoph Hellwig
2020-11-26 14:47   ` David Sterba
2020-11-27 12:03   ` Hannes Reinecke
2020-11-26 13:03 ` [dm-devel] [PATCH 13/44] block: use disk_part_iter_exit in disk_part_iter_next Christoph Hellwig
2020-11-27 12:04   ` Hannes Reinecke
2020-11-26 13:03 ` [dm-devel] [PATCH 14/44] block: use put_device in put_disk Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 15/44] block: change the hash used for looking up block devices Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 16/44] init: refactor name_to_dev_t Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 17/44] init: refactor devt_from_partuuid Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 18/44] init: cleanup match_dev_by_uuid and match_dev_by_label Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 19/44] block: refactor __blkdev_put Christoph Hellwig
2020-11-26 13:03 ` [dm-devel] [PATCH 20/44] block: refactor blkdev_get Christoph Hellwig
2020-11-26 14:55   ` Jan Kara
2020-11-26 13:03 ` [dm-devel] [PATCH 21/44] block: move bdput() to the callers of __blkdev_get Christoph Hellwig
2020-11-26 15:05   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 22/44] block: opencode devcgroup_inode_permission Christoph Hellwig
2020-11-26 15:07   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 23/44] block: remove i_bdev Christoph Hellwig
2020-11-26 15:45   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 24/44] block: simplify bdev/disk lookup in blkdev_get Christoph Hellwig
2020-11-26 16:33   ` Jan Kara
2020-11-26 17:42     ` Christoph Hellwig
2020-11-26 13:04 ` [dm-devel] [PATCH 25/44] block: remove ->bd_contains Christoph Hellwig
2020-11-26 13:04 ` [dm-devel] [PATCH 26/44] block: simplify the block device claiming interface Christoph Hellwig
2020-11-26 13:04 ` [dm-devel] [PATCH 27/44] block: simplify part_to_disk Christoph Hellwig
2020-11-26 16:36   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 28/44] block: initialize struct block_device in bdev_alloc Christoph Hellwig
2020-11-26 16:37   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 29/44] block: remove the nr_sects field in struct hd_struct Christoph Hellwig
2020-11-26 16:50   ` Jan Kara
2020-11-26 17:52     ` Christoph Hellwig
2020-11-26 18:04       ` Jan Kara
2020-11-27  9:41         ` Christoph Hellwig
2020-11-26 13:04 ` [dm-devel] [PATCH 30/44] block: move disk stat accounting to struct block_device Christoph Hellwig
2020-11-26 16:53   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 31/44] block: move the start_sect field " Christoph Hellwig
2020-11-26 16:56   ` Jan Kara
2020-11-26 18:02     ` Christoph Hellwig
2020-11-26 13:04 ` [dm-devel] [PATCH 32/44] block: move the partition_meta_info " Christoph Hellwig
2020-11-26 16:58   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 33/44] block: move holder_dir " Christoph Hellwig
2020-11-26 17:00   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 34/44] block: move make_it_fail " Christoph Hellwig
2020-11-26 17:01   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 35/44] block: move the policy field " Christoph Hellwig
2020-11-26 17:03   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 36/44] block: allocate struct hd_struct as part of struct bdev_inode Christoph Hellwig
2020-11-26 17:35   ` Jan Kara
2020-11-26 18:00     ` Jan Kara
2020-11-26 18:02       ` Christoph Hellwig
2020-11-26 13:04 ` [dm-devel] [PATCH 37/44] block: switch partition lookup to use struct block_device Christoph Hellwig
2020-11-26 17:45   ` Jan Kara
2020-11-26 18:22   ` Jan Kara
2020-11-27  9:48     ` Christoph Hellwig
2020-11-27 12:45       ` Jan Kara
2020-11-27 15:36         ` Christoph Hellwig
2020-11-27 17:26           ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 38/44] block: remove the partno field from struct hd_struct Christoph Hellwig
2020-11-26 17:46   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 39/44] block: pass a block_device to blk_alloc_devt Christoph Hellwig
2020-11-26 17:47   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 40/44] block: pass a block_device to invalidate_partition Christoph Hellwig
2020-11-26 17:49   ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 41/44] block: switch disk_part_iter_* to use a struct block_device Christoph Hellwig
2020-11-27 12:53   ` Jan Kara
2020-11-27 15:24     ` Christoph Hellwig
2020-11-27 17:30       ` Jan Kara
2020-11-26 13:04 ` [dm-devel] [PATCH 42/44] f2fs: remove a few bd_part checks Christoph Hellwig
2020-11-26 13:04 ` [dm-devel] [PATCH 43/44] block: merge struct block_device and struct hd_struct Christoph Hellwig
2020-11-27 13:19   ` Jan Kara
2020-11-27 15:47     ` Christoph Hellwig
2020-11-26 13:04 ` [dm-devel] [PATCH 44/44] block: stop using bdget_disk for partition 0 Christoph Hellwig
2020-11-27 13:22   ` Jan Kara

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