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
  11 /*
  12  * We use lowest available bit in exceptional entry for locking, one bit for
  13  * the entry size (PMD) and two more to tell us if the entry is a huge zero
  14  * page (HZP) or an empty entry that is just used for locking.  In total four
  15  * special bits.
  16  *
  17  * If the PMD bit isn't set the entry has size PAGE_SIZE, and if the HZP and
  18  * EMPTY bits aren't set the entry is a normal DAX entry with a filesystem
  19  * block allocation.
  20  */
  21 #define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 4)
  22 #define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT)
  23 #define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1))
  24 #define RADIX_DAX_HZP (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2))
  25 #define RADIX_DAX_EMPTY (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 3))
  26
  27 static inline unsigned long dax_radix_sector(void *entry)
  28 {
  29         return (unsigned long)entry >> RADIX_DAX_SHIFT;
  30 }
  31
  32 static inline void *dax_radix_locked_entry(sector_t sector, unsigned long flags)
  33 {
  34         return (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | flags |
  35                         ((unsigned long)sector << RADIX_DAX_SHIFT) |
  36                         RADIX_DAX_ENTRY_LOCK);
  37 }
  38
  39 ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
  40                 const struct iomap_ops *ops);
  41 int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
  42                     const struct iomap_ops *ops);
  43 int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
  44 int dax_invalidate_mapping_entry(struct address_space *mapping, pgoff_t index);
  45 int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
  46                                       pgoff_t index);
  47 void dax_wake_mapping_entry_waiter(struct address_space *mapping,
  48                 pgoff_t index, void *entry, bool wake_all);
  49
  50 #ifdef CONFIG_FS_DAX
  51 struct page *read_dax_sector(struct block_device *bdev, sector_t n);
  52 int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
  53                 unsigned int offset, unsigned int length);
  54 #else
  55 static inline struct page *read_dax_sector(struct block_device *bdev,
  56                 sector_t n)
  57 {
  58         return ERR_PTR(-ENXIO);
  59 }
  60 static inline int __dax_zero_page_range(struct block_device *bdev,
  61                 sector_t sector, unsigned int offset, unsigned int length)
  62 {
  63         return -ENXIO;
  64 }
  65 #endif
  66
  67 #ifdef CONFIG_FS_DAX_PMD
  68 static inline unsigned int dax_radix_order(void *entry)
  69 {
  70         if ((unsigned long)entry & RADIX_DAX_PMD)
  71                 return PMD_SHIFT - PAGE_SHIFT;
  72         return 0;
  73 }
  74 #else
  75 static inline unsigned int dax_radix_order(void *entry)
  76 {
  77         return 0;
  78 }
  79 #endif
  80 int dax_pfn_mkwrite(struct vm_fault *vmf);
  81
  82 static inline bool vma_is_dax(struct vm_area_struct *vma)
  83 {
  84         return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host);
  85 }
  86
  87 static inline bool dax_mapping(struct address_space *mapping)
  88 {
  89         return mapping->host && IS_DAX(mapping->host);
  90 }
  91
  92 struct writeback_control;
  93 int dax_writeback_mapping_range(struct address_space *mapping,
  94                 struct block_device *bdev, struct writeback_control *wbc);
  95 #endif