[dm-devel] [PATCH 5/5] dax, iomap: Add helper dax_iomap_zero() to zero a range
Christoph Hellwig
hch at infradead.org
Wed Feb 5 18:36:09 UTC 2020
> +int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size,
> + struct iomap *iomap)
> {
> pgoff_t pgoff;
> long rc, id;
> + sector_t sector = iomap_sector(iomap, pos & PAGE_MASK);
>
> - rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff);
> + rc = bdev_dax_pgoff(iomap->bdev, sector, PAGE_SIZE, &pgoff);
> if (rc)
> return rc;
>
> id = dax_read_lock();
> - rc = dax_zero_page_range(dax_dev, pgoff, offset, size);
> + rc = dax_zero_page_range(iomap->dax_dev, pgoff, offset, size);
> dax_read_unlock(id);
> return rc;
> }
> -EXPORT_SYMBOL_GPL(__dax_zero_page_range);
> +EXPORT_SYMBOL_GPL(dax_iomap_zero);
This function is only used by fs/iomap/buffered-io.c, so no need to
export it.
> #ifdef CONFIG_FS_DAX
> -int __dax_zero_page_range(struct block_device *bdev,
> - struct dax_device *dax_dev, sector_t sector,
> - unsigned int offset, unsigned int length);
> +int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size,
> + struct iomap *iomap);
> #else
> -static inline int __dax_zero_page_range(struct block_device *bdev,
> - struct dax_device *dax_dev, sector_t sector,
> - unsigned int offset, unsigned int length)
> +static inline int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size,
> + struct iomap *iomap)
> {
> return -ENXIO;
> }
Given that the only caller is under an IS_DAX() check you could just
declare the function unconditionally and let the compiler optimize
away the guaranteed dead call for the !CONFIG_FS_DAX case, like we
do with various other functions.
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