/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_DAX_H
#define _LINUX_DAX_H

#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/radix-tree.h>
#include <asm/pgtable.h>

typedef unsigned long dax_entry_t;

struct iomap_ops;
struct dax_device;
struct dax_operations {
        /*
         * direct_access: translate a device-relative
         * logical-page-offset into an absolute physical pfn. Return the
         * number of pages available for DAX at that pfn.
         */
        long (*direct_access)(struct dax_device *, pgoff_t, long,
                        void **, pfn_t *);
        /*
         * Validate whether this device is usable as an fsdax backing
         * device.
         */
        bool (*dax_supported)(struct dax_device *, struct block_device *, int,
                        sector_t, sector_t);
        /* copy_from_iter: required operation for fs-dax direct-i/o */
        size_t (*copy_from_iter)(struct dax_device *, pgoff_t, void *, size_t,
                        struct iov_iter *);
        /* copy_to_iter: required operation for fs-dax direct-i/o */
        size_t (*copy_to_iter)(struct dax_device *, pgoff_t, void *, size_t,
                        struct iov_iter *);
};

extern struct attribute_group dax_attribute_group;

#if IS_ENABLED(CONFIG_DAX)
struct dax_device *dax_get_by_host(const char *host);
struct dax_device *alloc_dax(void *private, const char *host,
                const struct dax_operations *ops);
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);
bool dax_write_cache_enabled(struct dax_device *dax_dev);
#else
static inline struct dax_device *dax_get_by_host(const char *host)
{
        return NULL;
}
static inline struct dax_device *alloc_dax(void *private, const char *host,
                const struct dax_operations *ops)
{
        /*
         * Callers should check IS_ENABLED(CONFIG_DAX) to know if this
         * NULL is an error or expected.
         */
        return NULL;
}
static inline void put_dax(struct dax_device *dax_dev)
{
}
static inline void kill_dax(struct dax_device *dax_dev)
{
}
static inline void dax_write_cache(struct dax_device *dax_dev, bool wc)
{
}
static inline bool dax_write_cache_enabled(struct dax_device *dax_dev)
{
        return false;
}
#endif

struct writeback_control;
int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
#if IS_ENABLED(CONFIG_FS_DAX)
bool __bdev_dax_supported(struct block_device *bdev, int blocksize);
static inline bool bdev_dax_supported(struct block_device *bdev, int blocksize)
{
        return __bdev_dax_supported(bdev, blocksize);
}

bool __generic_fsdax_supported(struct dax_device *dax_dev,
                struct block_device *bdev, int blocksize, sector_t start,
                sector_t sectors);
static inline bool generic_fsdax_supported(struct dax_device *dax_dev,
                struct block_device *bdev, int blocksize, sector_t start,
                sector_t sectors)
{
        return __generic_fsdax_supported(dax_dev, bdev, blocksize, start,
                        sectors);
}

static inline struct dax_device *fs_dax_get_by_host(const char *host)
{
        return dax_get_by_host(host);
}

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);
int dax_writeback_mapping_range(struct address_space *mapping,
                struct block_device *bdev, struct writeback_control *wbc);

struct page *dax_layout_busy_page(struct address_space *mapping);
dax_entry_t dax_lock_page(struct page *page);
void dax_unlock_page(struct page *page, dax_entry_t cookie);
#else
static inline bool bdev_dax_supported(struct block_device *bdev,
                int blocksize)
{
        return false;
}

static inline bool generic_fsdax_supported(struct dax_device *dax_dev,
                struct block_device *bdev, int blocksize, sector_t start,
                sector_t sectors)
{
        return false;
}

static inline struct dax_device *fs_dax_get_by_host(const char *host)
{
        return NULL;
}

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;
}

static inline struct page *dax_layout_busy_page(struct address_space *mapping)
{
        return NULL;
}

static inline int dax_writeback_mapping_range(struct address_space *mapping,
                struct block_device *bdev, struct writeback_control *wbc)
{
        return -EOPNOTSUPP;
}

static inline dax_entry_t dax_lock_page(struct page *page)
{
        if (IS_DAX(page->mapping->host))
                return ~0UL;
        return 0;
}

static inline void dax_unlock_page(struct page *page, dax_entry_t cookie)
{
}
#endif

int dax_read_lock(void);
void dax_read_unlock(int id);
bool dax_alive(struct dax_device *dax_dev);
void *dax_get_private(struct dax_device *dax_dev);
long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
                void **kaddr, pfn_t *pfn);
bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
                int blocksize, sector_t start, sector_t len);
size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
                size_t bytes, struct iov_iter *i);
size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
                size_t bytes, struct iov_iter *i);
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,
                const struct iomap_ops *ops);
vm_fault_t dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
                    pfn_t *pfnp, int *errp, const struct iomap_ops *ops);
vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
                enum page_entry_size pe_size, pfn_t pfn);
int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
                                      pgoff_t index);

#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);
#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)
{
        return -ENXIO;
}
#endif

static inline bool dax_mapping(struct address_space *mapping)
{
        return mapping->host && IS_DAX(mapping->host);
}

#endif