On Wed, Aug 30, 2017 at 12:43:52PM -0700, Dan Williams wrote:
> Add a helper that can replace the following common pattern:
>
> if (blk_queue_dax(bdev->bd_queue))
> fs_dax_get_by_host(bdev->bd_disk->disk_name);
>
> This will be used to move dax_device lookup from iomap-operation time to
> fs-mount time.
>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> drivers/dax/super.c | 10 ++++++++++
> include/linux/dax.h | 6 ++++++
> 2 files changed, 16 insertions(+)
>
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 938eb4868f7f..b699aac268a6 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -46,6 +46,8 @@ void dax_read_unlock(int id)
> EXPORT_SYMBOL_GPL(dax_read_unlock);
>
> #ifdef CONFIG_BLOCK
> +#include <linux/blkdev.h>
> +
> int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
> pgoff_t *pgoff)
> {
> @@ -59,6 +61,14 @@ int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
> }
> EXPORT_SYMBOL(bdev_dax_pgoff);
>
> +struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
> +{
> + if (!blk_queue_dax(bdev->bd_queue))
> + return NULL;
> + return fs_dax_get_by_host(bdev->bd_disk->disk_name);
> +}
> +EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
> +
> /**
> * __bdev_dax_supported() - Check if the device supports dax for filesystem
> * @sb: The superblock of the device
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index df97b7af7e2c..ac8afa18f707 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -57,6 +57,7 @@ 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);
> #else
> static inline int bdev_dax_supported(struct super_block *sb, int blocksize)
> {
> @@ -71,6 +72,11 @@ static inline struct dax_device *fs_dax_get_by_host(const char *host)
> static inline void fs_put_dax(struct dax_device *dax_dev)
> {
> }
> +
> +static inline struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
> +{
> + return NULL;
> +}
> #endif
>
> int dax_read_lock(void);
>
> --
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