1 #ifndef _LINUX_DAX_H 2 #define _LINUX_DAX_H 3 4 #include <linux/fs.h> 5 #include <linux/mm.h> 6 #include <linux/radix-tree.h> 7 #include <asm/pgtable.h> 8 9 struct iomap_ops; 10 struct dax_device; 11 struct dax_operations { 12 /* 13 * direct_access: translate a device-relative 14 * logical-page-offset into an absolute physical pfn. Return the 15 * number of pages available for DAX at that pfn. 16 */ 17 long (*direct_access)(struct dax_device *, pgoff_t, long, 18 void **, pfn_t *); 19 }; 20 21 int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff); 22 #if IS_ENABLED(CONFIG_FS_DAX) 23 int __bdev_dax_supported(struct super_block *sb, int blocksize); 24 static inline int bdev_dax_supported(struct super_block *sb, int blocksize) 25 { 26 return __bdev_dax_supported(sb, blocksize); 27 } 28 #else 29 static inline int bdev_dax_supported(struct super_block *sb, int blocksize) 30 { 31 return -EOPNOTSUPP; 32 } 33 #endif 34 35 #if IS_ENABLED(CONFIG_DAX) 36 struct dax_device *dax_get_by_host(const char *host); 37 void put_dax(struct dax_device *dax_dev); 38 #else 39 static inline struct dax_device *dax_get_by_host(const char *host) 40 { 41 return NULL; 42 } 43 44 static inline void put_dax(struct dax_device *dax_dev) 45 { 46 } 47 #endif 48 49 int dax_read_lock(void); 50 void dax_read_unlock(int id); 51 struct dax_device *alloc_dax(void *private, const char *host, 52 const struct dax_operations *ops); 53 bool dax_alive(struct dax_device *dax_dev); 54 void kill_dax(struct dax_device *dax_dev); 55 void *dax_get_private(struct dax_device *dax_dev); 56 long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages, 57 void **kaddr, pfn_t *pfn); 58 59 /* 60 * We use lowest available bit in exceptional entry for locking, one bit for 61 * the entry size (PMD) and two more to tell us if the entry is a huge zero 62 * page (HZP) or an empty entry that is just used for locking. In total four 63 * special bits. 64 * 65 * If the PMD bit isn't set the entry has size PAGE_SIZE, and if the HZP and 66 * EMPTY bits aren't set the entry is a normal DAX entry with a filesystem 67 * block allocation. 68 */ 69 #define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 4) 70 #define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT) 71 #define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1)) 72 #define RADIX_DAX_HZP (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2)) 73 #define RADIX_DAX_EMPTY (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 3)) 74 75 static inline unsigned long dax_radix_sector(void *entry) 76 { 77 return (unsigned long)entry >> RADIX_DAX_SHIFT; 78 } 79 80 static inline void *dax_radix_locked_entry(sector_t sector, unsigned long flags) 81 { 82 return (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | flags | 83 ((unsigned long)sector << RADIX_DAX_SHIFT) | 84 RADIX_DAX_ENTRY_LOCK); 85 } 86 87 ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter, 88 const struct iomap_ops *ops); 89 int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size, 90 const struct iomap_ops *ops); 91 int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index); 92 int dax_invalidate_mapping_entry_sync(struct address_space *mapping, 93 pgoff_t index); 94 void dax_wake_mapping_entry_waiter(struct address_space *mapping, 95 pgoff_t index, void *entry, bool wake_all); 96 97 #ifdef CONFIG_FS_DAX 98 int __dax_zero_page_range(struct block_device *bdev, 99 struct dax_device *dax_dev, sector_t sector, 100 unsigned int offset, unsigned int length); 101 #else 102 static inline int __dax_zero_page_range(struct block_device *bdev, 103 struct dax_device *dax_dev, sector_t sector, 104 unsigned int offset, unsigned int length) 105 { 106 return -ENXIO; 107 } 108 #endif 109 110 #ifdef CONFIG_FS_DAX_PMD 111 static inline unsigned int dax_radix_order(void *entry) 112 { 113 if ((unsigned long)entry & RADIX_DAX_PMD) 114 return PMD_SHIFT - PAGE_SHIFT; 115 return 0; 116 } 117 #else 118 static inline unsigned int dax_radix_order(void *entry) 119 { 120 return 0; 121 } 122 #endif 123 int dax_pfn_mkwrite(struct vm_fault *vmf); 124 125 static inline bool vma_is_dax(struct vm_area_struct *vma) 126 { 127 return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host); 128 } 129 130 static inline bool dax_mapping(struct address_space *mapping) 131 { 132 return mapping->host && IS_DAX(mapping->host); 133 } 134 135 struct writeback_control; 136 int dax_writeback_mapping_range(struct address_space *mapping, 137 struct block_device *bdev, struct writeback_control *wbc); 138 #endif 139