diff mbox series

[v13,1/7] dax: Introduce holder for dax_device

Message ID 20220419045045.1664996-2-ruansy.fnst@fujitsu.com (mailing list archive)
State New, archived
Headers show
Series fsdax: introduce fs query to support reflink | expand

Commit Message

Shiyang Ruan April 19, 2022, 4:50 a.m. UTC 
To easily track filesystem from a pmem device, we introduce a holder for
dax_device structure, and also its operation.  This holder is used to
remember who is using this dax_device:
 - When it is the backend of a filesystem, the holder will be the
   instance of this filesystem.
 - When this pmem device is one of the targets in a mapped device, the
   holder will be this mapped device.  In this case, the mapped device
   has its own dax_device and it will follow the first rule.  So that we
   can finally track to the filesystem we needed.

The holder and holder_ops will be set when filesystem is being mounted,
or an target device is being activated.

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.wiliams@intel.com>
---
 drivers/dax/super.c | 67 ++++++++++++++++++++++++++++++++++++++++++++-
 drivers/md/dm.c     |  2 +-
 fs/erofs/super.c    | 10 ++++---
 fs/ext2/super.c     |  7 +++--
 fs/ext4/super.c     |  9 +++---
 fs/xfs/xfs_buf.c    |  5 ++--
 include/linux/dax.h | 33 ++++++++++++++++------
 7 files changed, 110 insertions(+), 23 deletions(-)

Comments

Darrick J. Wong April 20, 2022, 5:42 p.m. UTC | #1 
On Tue, Apr 19, 2022 at 12:50:39PM +0800, Shiyang Ruan wrote:
> To easily track filesystem from a pmem device, we introduce a holder for
> dax_device structure, and also its operation.  This holder is used to
> remember who is using this dax_device:
>  - When it is the backend of a filesystem, the holder will be the
>    instance of this filesystem.
>  - When this pmem device is one of the targets in a mapped device, the
>    holder will be this mapped device.  In this case, the mapped device
>    has its own dax_device and it will follow the first rule.  So that we
>    can finally track to the filesystem we needed.
> 
> The holder and holder_ops will be set when filesystem is being mounted,
> or an target device is being activated.
> 
> Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Dan Williams <dan.j.wiliams@intel.com>

LGTM
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  drivers/dax/super.c | 67 ++++++++++++++++++++++++++++++++++++++++++++-
>  drivers/md/dm.c     |  2 +-
>  fs/erofs/super.c    | 10 ++++---
>  fs/ext2/super.c     |  7 +++--
>  fs/ext4/super.c     |  9 +++---
>  fs/xfs/xfs_buf.c    |  5 ++--
>  include/linux/dax.h | 33 ++++++++++++++++------
>  7 files changed, 110 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 0211e6f7b47a..5ddb159c4653 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -22,6 +22,8 @@
>   * @private: dax driver private data
>   * @flags: state and boolean properties
>   * @ops: operations for this device
> + * @holder_data: holder of a dax_device: could be filesystem or mapped device
> + * @holder_ops: operations for the inner holder
>   */
>  struct dax_device {
>  	struct inode inode;
> @@ -29,6 +31,8 @@ struct dax_device {
>  	void *private;
>  	unsigned long flags;
>  	const struct dax_operations *ops;
> +	void *holder_data;
> +	const struct dax_holder_operations *holder_ops;
>  };
>  
>  static dev_t dax_devt;
> @@ -71,8 +75,11 @@ EXPORT_SYMBOL_GPL(dax_remove_host);
>   * fs_dax_get_by_bdev() - temporary lookup mechanism for filesystem-dax
>   * @bdev: block device to find a dax_device for
>   * @start_off: returns the byte offset into the dax_device that @bdev starts
> + * @holder: filesystem or mapped device inside the dax_device
> + * @ops: operations for the inner holder
>   */
> -struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off)
> +struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off,
> +		void *holder, const struct dax_holder_operations *ops)
>  {
>  	struct dax_device *dax_dev;
>  	u64 part_size;
> @@ -92,11 +99,26 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off)
>  	dax_dev = xa_load(&dax_hosts, (unsigned long)bdev->bd_disk);
>  	if (!dax_dev || !dax_alive(dax_dev) || !igrab(&dax_dev->inode))
>  		dax_dev = NULL;
> +	else if (holder) {
> +		if (!cmpxchg(&dax_dev->holder_data, NULL, holder))
> +			dax_dev->holder_ops = ops;
> +		else
> +			dax_dev = NULL;
> +	}
>  	dax_read_unlock(id);
>  
>  	return dax_dev;
>  }
>  EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
> +
> +void fs_put_dax(struct dax_device *dax_dev, void *holder)
> +{
> +	if (dax_dev && holder &&
> +	    cmpxchg(&dax_dev->holder_data, holder, NULL) == holder)
> +		dax_dev->holder_ops = NULL;
> +	put_dax(dax_dev);
> +}
> +EXPORT_SYMBOL_GPL(fs_put_dax);
>  #endif /* CONFIG_BLOCK && CONFIG_FS_DAX */
>  
>  enum dax_device_flags {
> @@ -194,6 +216,29 @@ int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
>  }
>  EXPORT_SYMBOL_GPL(dax_zero_page_range);
>  
> +int dax_holder_notify_failure(struct dax_device *dax_dev, u64 off,
> +			      u64 len, int mf_flags)
> +{
> +	int rc, id;
> +
> +	id = dax_read_lock();
> +	if (!dax_alive(dax_dev)) {
> +		rc = -ENXIO;
> +		goto out;
> +	}
> +
> +	if (!dax_dev->holder_ops) {
> +		rc = -EOPNOTSUPP;
> +		goto out;
> +	}
> +
> +	rc = dax_dev->holder_ops->notify_failure(dax_dev, off, len, mf_flags);
> +out:
> +	dax_read_unlock(id);
> +	return rc;
> +}
> +EXPORT_SYMBOL_GPL(dax_holder_notify_failure);
> +
>  #ifdef CONFIG_ARCH_HAS_PMEM_API
>  void arch_wb_cache_pmem(void *addr, size_t size);
>  void dax_flush(struct dax_device *dax_dev, void *addr, size_t size)
> @@ -267,8 +312,15 @@ void kill_dax(struct dax_device *dax_dev)
>  	if (!dax_dev)
>  		return;
>  
> +	if (dax_dev->holder_data != NULL)
> +		dax_holder_notify_failure(dax_dev, 0, U64_MAX, 0);
> +
>  	clear_bit(DAXDEV_ALIVE, &dax_dev->flags);
>  	synchronize_srcu(&dax_srcu);
> +
> +	/* clear holder data */
> +	dax_dev->holder_ops = NULL;
> +	dax_dev->holder_data = NULL;
>  }
>  EXPORT_SYMBOL_GPL(kill_dax);
>  
> @@ -410,6 +462,19 @@ void put_dax(struct dax_device *dax_dev)
>  }
>  EXPORT_SYMBOL_GPL(put_dax);
>  
> +/**
> + * dax_holder() - obtain the holder of a dax device
> + * @dax_dev: a dax_device instance
> +
> + * Return: the holder's data which represents the holder if registered,
> + * otherwize NULL.
> + */
> +void *dax_holder(struct dax_device *dax_dev)
> +{
> +	return dax_dev->holder_data;
> +}
> +EXPORT_SYMBOL_GPL(dax_holder);
> +
>  /**
>   * inode_dax: convert a public inode into its dax_dev
>   * @inode: An inode with i_cdev pointing to a dax_dev
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 3c5fad7c4ee6..5906b4efc767 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -721,7 +721,7 @@ static int open_table_device(struct table_device *td, dev_t dev,
>  	}
>  
>  	td->dm_dev.bdev = bdev;
> -	td->dm_dev.dax_dev = fs_dax_get_by_bdev(bdev, &part_off);
> +	td->dm_dev.dax_dev = fs_dax_get_by_bdev(bdev, &part_off, NULL, NULL);
>  	return 0;
>  }
>  
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index 0c4b41130c2f..d0eab646ef94 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -267,7 +267,8 @@ static int erofs_init_devices(struct super_block *sb,
>  			break;
>  		}
>  		dif->bdev = bdev;
> -		dif->dax_dev = fs_dax_get_by_bdev(bdev, &dif->dax_part_off);
> +		dif->dax_dev = fs_dax_get_by_bdev(bdev, &dif->dax_part_off,
> +						  NULL, NULL);
>  		dif->blocks = le32_to_cpu(dis->blocks);
>  		dif->mapped_blkaddr = le32_to_cpu(dis->mapped_blkaddr);
>  		sbi->total_blocks += dif->blocks;
> @@ -597,7 +598,8 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>  
>  	sb->s_fs_info = sbi;
>  	sbi->opt = ctx->opt;
> -	sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->dax_part_off);
> +	sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->dax_part_off,
> +					  NULL, NULL);
>  	sbi->devs = ctx->devs;
>  	ctx->devs = NULL;
>  
> @@ -687,7 +689,7 @@ static int erofs_release_device_info(int id, void *ptr, void *data)
>  {
>  	struct erofs_device_info *dif = ptr;
>  
> -	fs_put_dax(dif->dax_dev);
> +	fs_put_dax(dif->dax_dev, NULL);
>  	if (dif->bdev)
>  		blkdev_put(dif->bdev, FMODE_READ | FMODE_EXCL);
>  	kfree(dif->path);
> @@ -756,7 +758,7 @@ static void erofs_kill_sb(struct super_block *sb)
>  		return;
>  
>  	erofs_free_dev_context(sbi->devs);
> -	fs_put_dax(sbi->dax_dev);
> +	fs_put_dax(sbi->dax_dev, NULL);
>  	kfree(sbi);
>  	sb->s_fs_info = NULL;
>  }
> diff --git a/fs/ext2/super.c b/fs/ext2/super.c
> index f6a19f6d9f6d..4638946251b9 100644
> --- a/fs/ext2/super.c
> +++ b/fs/ext2/super.c
> @@ -171,7 +171,7 @@ static void ext2_put_super (struct super_block * sb)
>  	brelse (sbi->s_sbh);
>  	sb->s_fs_info = NULL;
>  	kfree(sbi->s_blockgroup_lock);
> -	fs_put_dax(sbi->s_daxdev);
> +	fs_put_dax(sbi->s_daxdev, NULL);
>  	kfree(sbi);
>  }
>  
> @@ -835,7 +835,8 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
>  	}
>  	sb->s_fs_info = sbi;
>  	sbi->s_sb_block = sb_block;
> -	sbi->s_daxdev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->s_dax_part_off);
> +	sbi->s_daxdev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->s_dax_part_off,
> +					   NULL, NULL);
>  
>  	spin_lock_init(&sbi->s_lock);
>  	ret = -EINVAL;
> @@ -1204,7 +1205,7 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
>  failed_mount:
>  	brelse(bh);
>  failed_sbi:
> -	fs_put_dax(sbi->s_daxdev);
> +	fs_put_dax(sbi->s_daxdev, NULL);
>  	sb->s_fs_info = NULL;
>  	kfree(sbi->s_blockgroup_lock);
>  	kfree(sbi);
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index f5f4f2606ab2..59d5b2e8f838 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1300,7 +1300,7 @@ static void ext4_put_super(struct super_block *sb)
>  	if (sbi->s_chksum_driver)
>  		crypto_free_shash(sbi->s_chksum_driver);
>  	kfree(sbi->s_blockgroup_lock);
> -	fs_put_dax(sbi->s_daxdev);
> +	fs_put_dax(sbi->s_daxdev, NULL);
>  	fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy);
>  #if IS_ENABLED(CONFIG_UNICODE)
>  	utf8_unload(sb->s_encoding);
> @@ -4351,7 +4351,7 @@ static void ext4_free_sbi(struct ext4_sb_info *sbi)
>  		return;
>  
>  	kfree(sbi->s_blockgroup_lock);
> -	fs_put_dax(sbi->s_daxdev);
> +	fs_put_dax(sbi->s_daxdev, NULL);
>  	kfree(sbi);
>  }
>  
> @@ -4363,7 +4363,8 @@ static struct ext4_sb_info *ext4_alloc_sbi(struct super_block *sb)
>  	if (!sbi)
>  		return NULL;
>  
> -	sbi->s_daxdev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->s_dax_part_off);
> +	sbi->s_daxdev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->s_dax_part_off,
> +					   NULL, NULL);
>  
>  	sbi->s_blockgroup_lock =
>  		kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL);
> @@ -4375,7 +4376,7 @@ static struct ext4_sb_info *ext4_alloc_sbi(struct super_block *sb)
>  	sbi->s_sb = sb;
>  	return sbi;
>  err_out:
> -	fs_put_dax(sbi->s_daxdev);
> +	fs_put_dax(sbi->s_daxdev, NULL);
>  	kfree(sbi);
>  	return NULL;
>  }
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index e1afb9e503e1..f9ca08398d32 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -1911,7 +1911,7 @@ xfs_free_buftarg(
>  	list_lru_destroy(&btp->bt_lru);
>  
>  	blkdev_issue_flush(btp->bt_bdev);
> -	fs_put_dax(btp->bt_daxdev);
> +	fs_put_dax(btp->bt_daxdev, NULL);
>  
>  	kmem_free(btp);
>  }
> @@ -1964,7 +1964,8 @@ xfs_alloc_buftarg(
>  	btp->bt_mount = mp;
>  	btp->bt_dev =  bdev->bd_dev;
>  	btp->bt_bdev = bdev;
> -	btp->bt_daxdev = fs_dax_get_by_bdev(bdev, &btp->bt_dax_part_off);
> +	btp->bt_daxdev = fs_dax_get_by_bdev(bdev, &btp->bt_dax_part_off, NULL,
> +					    NULL);
>  
>  	/*
>  	 * Buffer IO error rate limiting. Limit it to no more than 10 messages
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index 9fc5f99a0ae2..9c426a207ba8 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -32,8 +32,21 @@ struct dax_operations {
>  	int (*zero_page_range)(struct dax_device *, pgoff_t, size_t);
>  };
>  
> +struct dax_holder_operations {
> +	/*
> +	 * notify_failure - notify memory failure into inner holder device
> +	 * @dax_dev: the dax device which contains the holder
> +	 * @offset: offset on this dax device where memory failure occurs
> +	 * @len: length of this memory failure event
> +	 * @flags: action flags for memory failure handler
> +	 */
> +	int (*notify_failure)(struct dax_device *dax_dev, u64 offset,
> +			u64 len, int mf_flags);
> +};
> +
>  #if IS_ENABLED(CONFIG_DAX)
>  struct dax_device *alloc_dax(void *private, const struct dax_operations *ops);
> +void *dax_holder(struct dax_device *dax_dev);
>  void put_dax(struct dax_device *dax_dev);
>  void kill_dax(struct dax_device *dax_dev);
>  void dax_write_cache(struct dax_device *dax_dev, bool wc);
> @@ -53,6 +66,10 @@ static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
>  	return dax_synchronous(dax_dev);
>  }
>  #else
> +static inline void *dax_holder(struct dax_device *dax_dev)
> +{
> +	return NULL;
> +}
>  static inline struct dax_device *alloc_dax(void *private,
>  		const struct dax_operations *ops)
>  {
> @@ -96,12 +113,9 @@ struct writeback_control;
>  #if defined(CONFIG_BLOCK) && defined(CONFIG_FS_DAX)
>  int dax_add_host(struct dax_device *dax_dev, struct gendisk *disk);
>  void dax_remove_host(struct gendisk *disk);
> -struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev,
> -		u64 *start_off);
> -static inline void fs_put_dax(struct dax_device *dax_dev)
> -{
> -	put_dax(dax_dev);
> -}
> +struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off,
> +		void *holder, const struct dax_holder_operations *ops);
> +void fs_put_dax(struct dax_device *dax_dev, void *holder);
>  #else
>  static inline int dax_add_host(struct dax_device *dax_dev, struct gendisk *disk)
>  {
> @@ -111,11 +125,12 @@ static inline void dax_remove_host(struct gendisk *disk)
>  {
>  }
>  static inline struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev,
> -		u64 *start_off)
> +		u64 *start_off, void *holder,
> +		const struct dax_holder_operations *ops)
>  {
>  	return NULL;
>  }
> -static inline void fs_put_dax(struct dax_device *dax_dev)
> +static inline void fs_put_dax(struct dax_device *dax_dev, void *holder)
>  {
>  }
>  #endif /* CONFIG_BLOCK && CONFIG_FS_DAX */
> @@ -185,6 +200,8 @@ size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
>  		size_t bytes, struct iov_iter *i);
>  int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
>  			size_t nr_pages);
> +int dax_holder_notify_failure(struct dax_device *dax_dev, u64 off, u64 len,
> +		int mf_flags);
>  void dax_flush(struct dax_device *dax_dev, void *addr, size_t size);
>  
>  ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
> -- 
> 2.35.1
> 
> 
>
diff mbox series

Patch

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 0211e6f7b47a..5ddb159c4653 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -22,6 +22,8 @@ 
  * @private: dax driver private data
  * @flags: state and boolean properties
  * @ops: operations for this device
+ * @holder_data: holder of a dax_device: could be filesystem or mapped device
+ * @holder_ops: operations for the inner holder
  */
 struct dax_device {
 	struct inode inode;
@@ -29,6 +31,8 @@  struct dax_device {
 	void *private;
 	unsigned long flags;
 	const struct dax_operations *ops;
+	void *holder_data;
+	const struct dax_holder_operations *holder_ops;
 };
 
 static dev_t dax_devt;
@@ -71,8 +75,11 @@  EXPORT_SYMBOL_GPL(dax_remove_host);
  * fs_dax_get_by_bdev() - temporary lookup mechanism for filesystem-dax
  * @bdev: block device to find a dax_device for
  * @start_off: returns the byte offset into the dax_device that @bdev starts
+ * @holder: filesystem or mapped device inside the dax_device
+ * @ops: operations for the inner holder
  */
-struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off)
+struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off,
+		void *holder, const struct dax_holder_operations *ops)
 {
 	struct dax_device *dax_dev;
 	u64 part_size;
@@ -92,11 +99,26 @@  struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off)
 	dax_dev = xa_load(&dax_hosts, (unsigned long)bdev->bd_disk);
 	if (!dax_dev || !dax_alive(dax_dev) || !igrab(&dax_dev->inode))
 		dax_dev = NULL;
+	else if (holder) {
+		if (!cmpxchg(&dax_dev->holder_data, NULL, holder))
+			dax_dev->holder_ops = ops;
+		else
+			dax_dev = NULL;
+	}
 	dax_read_unlock(id);
 
 	return dax_dev;
 }
 EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
+
+void fs_put_dax(struct dax_device *dax_dev, void *holder)
+{
+	if (dax_dev && holder &&
+	    cmpxchg(&dax_dev->holder_data, holder, NULL) == holder)
+		dax_dev->holder_ops = NULL;
+	put_dax(dax_dev);
+}
+EXPORT_SYMBOL_GPL(fs_put_dax);
 #endif /* CONFIG_BLOCK && CONFIG_FS_DAX */
 
 enum dax_device_flags {
@@ -194,6 +216,29 @@  int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
 }
 EXPORT_SYMBOL_GPL(dax_zero_page_range);
 
+int dax_holder_notify_failure(struct dax_device *dax_dev, u64 off,
+			      u64 len, int mf_flags)
+{
+	int rc, id;
+
+	id = dax_read_lock();
+	if (!dax_alive(dax_dev)) {
+		rc = -ENXIO;
+		goto out;
+	}
+
+	if (!dax_dev->holder_ops) {
+		rc = -EOPNOTSUPP;
+		goto out;
+	}
+
+	rc = dax_dev->holder_ops->notify_failure(dax_dev, off, len, mf_flags);
+out:
+	dax_read_unlock(id);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(dax_holder_notify_failure);
+
 #ifdef CONFIG_ARCH_HAS_PMEM_API
 void arch_wb_cache_pmem(void *addr, size_t size);
 void dax_flush(struct dax_device *dax_dev, void *addr, size_t size)
@@ -267,8 +312,15 @@  void kill_dax(struct dax_device *dax_dev)
 	if (!dax_dev)
 		return;
 
+	if (dax_dev->holder_data != NULL)
+		dax_holder_notify_failure(dax_dev, 0, U64_MAX, 0);
+
 	clear_bit(DAXDEV_ALIVE, &dax_dev->flags);
 	synchronize_srcu(&dax_srcu);
+
+	/* clear holder data */
+	dax_dev->holder_ops = NULL;
+	dax_dev->holder_data = NULL;
 }
 EXPORT_SYMBOL_GPL(kill_dax);
 
@@ -410,6 +462,19 @@  void put_dax(struct dax_device *dax_dev)
 }
 EXPORT_SYMBOL_GPL(put_dax);
 
+/**
+ * dax_holder() - obtain the holder of a dax device
+ * @dax_dev: a dax_device instance
+
+ * Return: the holder's data which represents the holder if registered,
+ * otherwize NULL.
+ */
+void *dax_holder(struct dax_device *dax_dev)
+{
+	return dax_dev->holder_data;
+}
+EXPORT_SYMBOL_GPL(dax_holder);
+
 /**
  * inode_dax: convert a public inode into its dax_dev
  * @inode: An inode with i_cdev pointing to a dax_dev
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 3c5fad7c4ee6..5906b4efc767 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -721,7 +721,7 @@  static int open_table_device(struct table_device *td, dev_t dev,
 	}
 
 	td->dm_dev.bdev = bdev;
-	td->dm_dev.dax_dev = fs_dax_get_by_bdev(bdev, &part_off);
+	td->dm_dev.dax_dev = fs_dax_get_by_bdev(bdev, &part_off, NULL, NULL);
 	return 0;
 }
 
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 0c4b41130c2f..d0eab646ef94 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -267,7 +267,8 @@  static int erofs_init_devices(struct super_block *sb,
 			break;
 		}
 		dif->bdev = bdev;
-		dif->dax_dev = fs_dax_get_by_bdev(bdev, &dif->dax_part_off);
+		dif->dax_dev = fs_dax_get_by_bdev(bdev, &dif->dax_part_off,
+						  NULL, NULL);
 		dif->blocks = le32_to_cpu(dis->blocks);
 		dif->mapped_blkaddr = le32_to_cpu(dis->mapped_blkaddr);
 		sbi->total_blocks += dif->blocks;
@@ -597,7 +598,8 @@  static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
 
 	sb->s_fs_info = sbi;
 	sbi->opt = ctx->opt;
-	sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->dax_part_off);
+	sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->dax_part_off,
+					  NULL, NULL);
 	sbi->devs = ctx->devs;
 	ctx->devs = NULL;
 
@@ -687,7 +689,7 @@  static int erofs_release_device_info(int id, void *ptr, void *data)
 {
 	struct erofs_device_info *dif = ptr;
 
-	fs_put_dax(dif->dax_dev);
+	fs_put_dax(dif->dax_dev, NULL);
 	if (dif->bdev)
 		blkdev_put(dif->bdev, FMODE_READ | FMODE_EXCL);
 	kfree(dif->path);
@@ -756,7 +758,7 @@  static void erofs_kill_sb(struct super_block *sb)
 		return;
 
 	erofs_free_dev_context(sbi->devs);
-	fs_put_dax(sbi->dax_dev);
+	fs_put_dax(sbi->dax_dev, NULL);
 	kfree(sbi);
 	sb->s_fs_info = NULL;
 }
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index f6a19f6d9f6d..4638946251b9 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -171,7 +171,7 @@  static void ext2_put_super (struct super_block * sb)
 	brelse (sbi->s_sbh);
 	sb->s_fs_info = NULL;
 	kfree(sbi->s_blockgroup_lock);
-	fs_put_dax(sbi->s_daxdev);
+	fs_put_dax(sbi->s_daxdev, NULL);
 	kfree(sbi);
 }
 
@@ -835,7 +835,8 @@  static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 	}
 	sb->s_fs_info = sbi;
 	sbi->s_sb_block = sb_block;
-	sbi->s_daxdev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->s_dax_part_off);
+	sbi->s_daxdev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->s_dax_part_off,
+					   NULL, NULL);
 
 	spin_lock_init(&sbi->s_lock);
 	ret = -EINVAL;
@@ -1204,7 +1205,7 @@  static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 failed_mount:
 	brelse(bh);
 failed_sbi:
-	fs_put_dax(sbi->s_daxdev);
+	fs_put_dax(sbi->s_daxdev, NULL);
 	sb->s_fs_info = NULL;
 	kfree(sbi->s_blockgroup_lock);
 	kfree(sbi);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index f5f4f2606ab2..59d5b2e8f838 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1300,7 +1300,7 @@  static void ext4_put_super(struct super_block *sb)
 	if (sbi->s_chksum_driver)
 		crypto_free_shash(sbi->s_chksum_driver);
 	kfree(sbi->s_blockgroup_lock);
-	fs_put_dax(sbi->s_daxdev);
+	fs_put_dax(sbi->s_daxdev, NULL);
 	fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy);
 #if IS_ENABLED(CONFIG_UNICODE)
 	utf8_unload(sb->s_encoding);
@@ -4351,7 +4351,7 @@  static void ext4_free_sbi(struct ext4_sb_info *sbi)
 		return;
 
 	kfree(sbi->s_blockgroup_lock);
-	fs_put_dax(sbi->s_daxdev);
+	fs_put_dax(sbi->s_daxdev, NULL);
 	kfree(sbi);
 }
 
@@ -4363,7 +4363,8 @@  static struct ext4_sb_info *ext4_alloc_sbi(struct super_block *sb)
 	if (!sbi)
 		return NULL;
 
-	sbi->s_daxdev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->s_dax_part_off);
+	sbi->s_daxdev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->s_dax_part_off,
+					   NULL, NULL);
 
 	sbi->s_blockgroup_lock =
 		kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL);
@@ -4375,7 +4376,7 @@  static struct ext4_sb_info *ext4_alloc_sbi(struct super_block *sb)
 	sbi->s_sb = sb;
 	return sbi;
 err_out:
-	fs_put_dax(sbi->s_daxdev);
+	fs_put_dax(sbi->s_daxdev, NULL);
 	kfree(sbi);
 	return NULL;
 }
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index e1afb9e503e1..f9ca08398d32 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1911,7 +1911,7 @@  xfs_free_buftarg(
 	list_lru_destroy(&btp->bt_lru);
 
 	blkdev_issue_flush(btp->bt_bdev);
-	fs_put_dax(btp->bt_daxdev);
+	fs_put_dax(btp->bt_daxdev, NULL);
 
 	kmem_free(btp);
 }
@@ -1964,7 +1964,8 @@  xfs_alloc_buftarg(
 	btp->bt_mount = mp;
 	btp->bt_dev =  bdev->bd_dev;
 	btp->bt_bdev = bdev;
-	btp->bt_daxdev = fs_dax_get_by_bdev(bdev, &btp->bt_dax_part_off);
+	btp->bt_daxdev = fs_dax_get_by_bdev(bdev, &btp->bt_dax_part_off, NULL,
+					    NULL);
 
 	/*
 	 * Buffer IO error rate limiting. Limit it to no more than 10 messages
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 9fc5f99a0ae2..9c426a207ba8 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -32,8 +32,21 @@  struct dax_operations {
 	int (*zero_page_range)(struct dax_device *, pgoff_t, size_t);
 };
 
+struct dax_holder_operations {
+	/*
+	 * notify_failure - notify memory failure into inner holder device
+	 * @dax_dev: the dax device which contains the holder
+	 * @offset: offset on this dax device where memory failure occurs
+	 * @len: length of this memory failure event
+	 * @flags: action flags for memory failure handler
+	 */
+	int (*notify_failure)(struct dax_device *dax_dev, u64 offset,
+			u64 len, int mf_flags);
+};
+
 #if IS_ENABLED(CONFIG_DAX)
 struct dax_device *alloc_dax(void *private, const struct dax_operations *ops);
+void *dax_holder(struct dax_device *dax_dev);
 void put_dax(struct dax_device *dax_dev);
 void kill_dax(struct dax_device *dax_dev);
 void dax_write_cache(struct dax_device *dax_dev, bool wc);
@@ -53,6 +66,10 @@  static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
 	return dax_synchronous(dax_dev);
 }
 #else
+static inline void *dax_holder(struct dax_device *dax_dev)
+{
+	return NULL;
+}
 static inline struct dax_device *alloc_dax(void *private,
 		const struct dax_operations *ops)
 {
@@ -96,12 +113,9 @@  struct writeback_control;
 #if defined(CONFIG_BLOCK) && defined(CONFIG_FS_DAX)
 int dax_add_host(struct dax_device *dax_dev, struct gendisk *disk);
 void dax_remove_host(struct gendisk *disk);
-struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev,
-		u64 *start_off);
-static inline void fs_put_dax(struct dax_device *dax_dev)
-{
-	put_dax(dax_dev);
-}
+struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off,
+		void *holder, const struct dax_holder_operations *ops);
+void fs_put_dax(struct dax_device *dax_dev, void *holder);
 #else
 static inline int dax_add_host(struct dax_device *dax_dev, struct gendisk *disk)
 {
@@ -111,11 +125,12 @@  static inline void dax_remove_host(struct gendisk *disk)
 {
 }
 static inline struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev,
-		u64 *start_off)
+		u64 *start_off, void *holder,
+		const struct dax_holder_operations *ops)
 {
 	return NULL;
 }
-static inline void fs_put_dax(struct dax_device *dax_dev)
+static inline void fs_put_dax(struct dax_device *dax_dev, void *holder)
 {
 }
 #endif /* CONFIG_BLOCK && CONFIG_FS_DAX */
@@ -185,6 +200,8 @@  size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
 		size_t bytes, struct iov_iter *i);
 int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
 			size_t nr_pages);
+int dax_holder_notify_failure(struct dax_device *dax_dev, u64 off, u64 len,
+		int mf_flags);
 void dax_flush(struct dax_device *dax_dev, void *addr, size_t size);
 
 ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,