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 /* 49 * Both data and metadata needs to track how many readers are for the 50 * page. 51 * Data relies on @readers to unlock the page when last reader finished. 52 * While metadata doesn't need page unlock, it needs to prevent 53 * page::private get cleared before the last end_page_read(). 54 */ 55 atomic_t readers; 56 union { 57 /* 58 * Structures only used by metadata 59 * 60 * @eb_refs should only be operated under private_lock, as it 61 * manages whether the subpage can be detached. 62 */ 63 atomic_t eb_refs; 64 65 /* Structures only used by data */ 66 atomic_t writers; 67 }; 68 unsigned long bitmaps[]; 69 }; 70 71 enum btrfs_subpage_type { 72 BTRFS_SUBPAGE_METADATA, 73 BTRFS_SUBPAGE_DATA, 74 }; 75 76 #if PAGE_SIZE > SZ_4K 77 bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct address_space *mapping); 78 #else 79 static inline bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, 80 struct address_space *mapping) 81 { 82 return false; 83 } 84 #endif 85 86 int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info, 87 struct folio *folio, enum btrfs_subpage_type type); 88 void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, struct folio *folio); 89 90 /* Allocate additional data where page represents more than one sector */ 91 struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info, 92 enum btrfs_subpage_type type); 93 void btrfs_free_subpage(struct btrfs_subpage *subpage); 94 95 void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio); 96 void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio); 97 98 void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info, 99 struct folio *folio, u64 start, u32 len); 100 void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info, 101 struct folio *folio, u64 start, u32 len); 102 103 int btrfs_folio_start_writer_lock(const struct btrfs_fs_info *fs_info, 104 struct folio *folio, u64 start, u32 len); 105 void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info, 106 struct folio *folio, u64 start, u32 len); 107 void btrfs_folio_set_writer_lock(const struct btrfs_fs_info *fs_info, 108 struct folio *folio, u64 start, u32 len); 109 void btrfs_folio_end_writer_lock_bitmap(const struct btrfs_fs_info *fs_info, 110 struct folio *folio, unsigned long bitmap); 111 bool btrfs_subpage_find_writer_locked(const struct btrfs_fs_info *fs_info, 112 struct folio *folio, u64 search_start, 113 u64 *found_start_ret, u32 *found_len_ret); 114 115 /* 116 * Template for subpage related operations. 117 * 118 * btrfs_subpage_*() are for call sites where the folio has subpage attached and 119 * the range is ensured to be inside the folio's single page. 120 * 121 * btrfs_folio_*() are for call sites where the page can either be subpage 122 * specific or regular folios. The function will handle both cases. 123 * But the range still needs to be inside one single page. 124 * 125 * btrfs_folio_clamp_*() are similar to btrfs_folio_*(), except the range doesn't 126 * need to be inside the page. Those functions will truncate the range 127 * automatically. 128 */ 129 #define DECLARE_BTRFS_SUBPAGE_OPS(name) \ 130 void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \ 131 struct folio *folio, u64 start, u32 len); \ 132 void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \ 133 struct folio *folio, u64 start, u32 len); \ 134 bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \ 135 struct folio *folio, u64 start, u32 len); \ 136 void btrfs_folio_set_##name(const struct btrfs_fs_info *fs_info, \ 137 struct folio *folio, u64 start, u32 len); \ 138 void btrfs_folio_clear_##name(const struct btrfs_fs_info *fs_info, \ 139 struct folio *folio, u64 start, u32 len); \ 140 bool btrfs_folio_test_##name(const struct btrfs_fs_info *fs_info, \ 141 struct folio *folio, u64 start, u32 len); \ 142 void btrfs_folio_clamp_set_##name(const struct btrfs_fs_info *fs_info, \ 143 struct folio *folio, u64 start, u32 len); \ 144 void btrfs_folio_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \ 145 struct folio *folio, u64 start, u32 len); \ 146 bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info, \ 147 struct folio *folio, u64 start, u32 len); 148 149 DECLARE_BTRFS_SUBPAGE_OPS(uptodate); 150 DECLARE_BTRFS_SUBPAGE_OPS(dirty); 151 DECLARE_BTRFS_SUBPAGE_OPS(writeback); 152 DECLARE_BTRFS_SUBPAGE_OPS(ordered); 153 DECLARE_BTRFS_SUBPAGE_OPS(checked); 154 155 bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info, 156 struct folio *folio, u64 start, u32 len); 157 158 void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info, 159 struct folio *folio, u64 start, u32 len); 160 void btrfs_get_subpage_dirty_bitmap(struct btrfs_fs_info *fs_info, 161 struct folio *folio, 162 unsigned long *ret_bitmap); 163 void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info, 164 struct folio *folio, u64 start, u32 len); 165 166 #endif 167