include/linux/dax.h

   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 dax_read_lock(void);
  22 void dax_read_unlock(int id);
  23 struct dax_device *dax_get_by_host(const char *host);
  24 struct dax_device *alloc_dax(void *private, const char *host,
  25                 const struct dax_operations *ops);
  26 void put_dax(struct dax_device *dax_dev);
  27 bool dax_alive(struct dax_device *dax_dev);
  28 void kill_dax(struct dax_device *dax_dev);
  29 void *dax_get_private(struct dax_device *dax_dev);
  30 long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
  31                 void **kaddr, pfn_t *pfn);
  32
  33 /*
  34  * We use lowest available bit in exceptional entry for locking, one bit for
  35  * the entry size (PMD) and two more to tell us if the entry is a huge zero
  36  * page (HZP) or an empty entry that is just used for locking.  In total four
  37  * special bits.
  38  *
  39  * If the PMD bit isn't set the entry has size PAGE_SIZE, and if the HZP and
  40  * EMPTY bits aren't set the entry is a normal DAX entry with a filesystem
  41  * block allocation.
  42  */
  43 #define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 4)
  44 #define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT)
  45 #define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1))
  46 #define RADIX_DAX_HZP (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2))
  47 #define RADIX_DAX_EMPTY (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 3))
  48
  49 static inline unsigned long dax_radix_sector(void *entry)
  50 {
  51         return (unsigned long)entry >> RADIX_DAX_SHIFT;
  52 }
  53
  54 static inline void *dax_radix_locked_entry(sector_t sector, unsigned long flags)
  55 {
  56         return (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | flags |
  57                         ((unsigned long)sector << RADIX_DAX_SHIFT) |
  58                         RADIX_DAX_ENTRY_LOCK);
  59 }
  60
  61 ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
  62                 const struct iomap_ops *ops);
  63 int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
  64                     const struct iomap_ops *ops);
  65 int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
  66 int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
  67                                       pgoff_t index);
  68 void dax_wake_mapping_entry_waiter(struct address_space *mapping,
  69                 pgoff_t index, void *entry, bool wake_all);
  70
  71 #ifdef CONFIG_FS_DAX
  72 int __dax_zero_page_range(struct block_device *bdev,
  73                 struct dax_device *dax_dev, sector_t sector,
  74                 unsigned int offset, unsigned int length);
  75 #else
  76 static inline int __dax_zero_page_range(struct block_device *bdev,
  77                 struct dax_device *dax_dev, sector_t sector,
  78                 unsigned int offset, unsigned int length)
  79 {
  80         return -ENXIO;
  81 }
  82 #endif
  83
  84 #ifdef CONFIG_FS_DAX_PMD
  85 static inline unsigned int dax_radix_order(void *entry)
  86 {
  87         if ((unsigned long)entry & RADIX_DAX_PMD)
  88                 return PMD_SHIFT - PAGE_SHIFT;
  89         return 0;
  90 }
  91 #else
  92 static inline unsigned int dax_radix_order(void *entry)
  93 {
  94         return 0;
  95 }
  96 #endif
  97 int dax_pfn_mkwrite(struct vm_fault *vmf);
  98
  99 static inline bool vma_is_dax(struct vm_area_struct *vma)
 100 {
 101         return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host);
 102 }
 103
 104 static inline bool dax_mapping(struct address_space *mapping)
 105 {
 106         return mapping->host && IS_DAX(mapping->host);
 107 }
 108
 109 struct writeback_control;
 110 int dax_writeback_mapping_range(struct address_space *mapping,
 111                 struct block_device *bdev, struct writeback_control *wbc);
 112 #endif