fs/btrfs/subpage.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2
   3 #ifndef BTRFS_SUBPAGE_H
   4 #define BTRFS_SUBPAGE_H
   5
   6 #include <linux/spinlock.h>
   7 #include <linux/atomic.h>
   8 #include <linux/sizes.h>
   9
  10 struct address_space;
  11 struct folio;
  12 struct btrfs_fs_info;
  13
  14 /*
  15  * Extra info for subpapge bitmap.
  16  *
  17  * For subpage we pack all uptodate/dirty/writeback/ordered bitmaps into
  18  * one larger bitmap.
  19  *
  20  * This structure records how they are organized in the bitmap:
  21  *
  22  * /- uptodate          /- dirty        /- ordered
  23  * |                    |               |
  24  * v                    v               v
  25  * |u|u|u|u|........|u|u|d|d|.......|d|d|o|o|.......|o|o|
  26  * |< sectors_per_page >|
  27  *
  28  * Unlike regular macro-like enums, here we do not go upper-case names, as
  29  * these names will be utilized in various macros to define function names.
  30  */
  31 enum {
  32         btrfs_bitmap_nr_uptodate = 0,
  33         btrfs_bitmap_nr_dirty,
  34         btrfs_bitmap_nr_writeback,
  35         btrfs_bitmap_nr_ordered,
  36         btrfs_bitmap_nr_checked,
  37         btrfs_bitmap_nr_locked,
  38         btrfs_bitmap_nr_max
  39 };
  40
  41 /*
  42  * Structure to trace status of each sector inside a page, attached to
  43  * page::private for both data and metadata inodes.
  44  */
  45 struct btrfs_subpage {
  46         /* Common members for both data and metadata pages */
  47         spinlock_t lock;
  48         union {
  49                 /*
  50                  * Structures only used by metadata
  51                  *
  52                  * @eb_refs should only be operated under private_lock, as it
  53                  * manages whether the subpage can be detached.
  54                  */
  55                 atomic_t eb_refs;
  56
  57                 /*
  58                  * Structures only used by data,
  59                  *
  60                  * How many sectors inside the page is locked.
  61                  */
  62                 atomic_t nr_locked;
  63         };
  64         unsigned long bitmaps[];
  65 };
  66
  67 enum btrfs_subpage_type {
  68         BTRFS_SUBPAGE_METADATA,
  69         BTRFS_SUBPAGE_DATA,
  70 };
  71
  72 #if PAGE_SIZE > SZ_4K
  73 bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct address_space *mapping);
  74 #else
  75 static inline bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info,
  76                                     struct address_space *mapping)
  77 {
  78         return false;
  79 }
  80 #endif
  81
  82 int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
  83                          struct folio *folio, enum btrfs_subpage_type type);
  84 void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, struct folio *folio);
  85
  86 /* Allocate additional data where page represents more than one sector */
  87 struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
  88                                           enum btrfs_subpage_type type);
  89 void btrfs_free_subpage(struct btrfs_subpage *subpage);
  90
  91 void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
  92 void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
  93
  94 void btrfs_folio_end_lock(const struct btrfs_fs_info *fs_info,
  95                           struct folio *folio, u64 start, u32 len);
  96 void btrfs_folio_set_lock(const struct btrfs_fs_info *fs_info,
  97                           struct folio *folio, u64 start, u32 len);
  98 void btrfs_folio_end_lock_bitmap(const struct btrfs_fs_info *fs_info,
  99                                  struct folio *folio, unsigned long bitmap);
 100 /*
 101  * Template for subpage related operations.
 102  *
 103  * btrfs_subpage_*() are for call sites where the folio has subpage attached and
 104  * the range is ensured to be inside the folio's single page.
 105  *
 106  * btrfs_folio_*() are for call sites where the page can either be subpage
 107  * specific or regular folios. The function will handle both cases.
 108  * But the range still needs to be inside one single page.
 109  *
 110  * btrfs_folio_clamp_*() are similar to btrfs_folio_*(), except the range doesn't
 111  * need to be inside the page. Those functions will truncate the range
 112  * automatically.
 113  */
 114 #define DECLARE_BTRFS_SUBPAGE_OPS(name)                                 \
 115 void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info,      \
 116                 struct folio *folio, u64 start, u32 len);                       \
 117 void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info,    \
 118                 struct folio *folio, u64 start, u32 len);                       \
 119 bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info,     \
 120                 struct folio *folio, u64 start, u32 len);                       \
 121 void btrfs_folio_set_##name(const struct btrfs_fs_info *fs_info,        \
 122                 struct folio *folio, u64 start, u32 len);                       \
 123 void btrfs_folio_clear_##name(const struct btrfs_fs_info *fs_info,      \
 124                 struct folio *folio, u64 start, u32 len);                       \
 125 bool btrfs_folio_test_##name(const struct btrfs_fs_info *fs_info,       \
 126                 struct folio *folio, u64 start, u32 len);                       \
 127 void btrfs_folio_clamp_set_##name(const struct btrfs_fs_info *fs_info,  \
 128                 struct folio *folio, u64 start, u32 len);                       \
 129 void btrfs_folio_clamp_clear_##name(const struct btrfs_fs_info *fs_info,        \
 130                 struct folio *folio, u64 start, u32 len);                       \
 131 bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info, \
 132                 struct folio *folio, u64 start, u32 len);
 133
 134 DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
 135 DECLARE_BTRFS_SUBPAGE_OPS(dirty);
 136 DECLARE_BTRFS_SUBPAGE_OPS(writeback);
 137 DECLARE_BTRFS_SUBPAGE_OPS(ordered);
 138 DECLARE_BTRFS_SUBPAGE_OPS(checked);
 139
 140 bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
 141                                         struct folio *folio, u64 start, u32 len);
 142
 143 void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info,
 144                                   struct folio *folio, u64 start, u32 len);
 145 void btrfs_get_subpage_dirty_bitmap(struct btrfs_fs_info *fs_info,
 146                                     struct folio *folio,
 147                                     unsigned long *ret_bitmap);
 148 void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info,
 149                                       struct folio *folio, u64 start, u32 len);
 150
 151 #endif