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 9 struct address_space; 10 struct folio; 11 struct btrfs_fs_info; 12 13 /* 14 * Extra info for subpapge bitmap. 15 * 16 * For subpage we pack all uptodate/dirty/writeback/ordered bitmaps into 17 * one larger bitmap. 18 * 19 * This structure records how they are organized in the bitmap: 20 * 21 * /- uptodate_offset /- dirty_offset /- ordered_offset 22 * | | | 23 * v v v 24 * |u|u|u|u|........|u|u|d|d|.......|d|d|o|o|.......|o|o| 25 * |<- bitmap_nr_bits ->| 26 * |<----------------- total_nr_bits ------------------>| 27 */ 28 struct btrfs_subpage_info { 29 /* Number of bits for each bitmap */ 30 unsigned int bitmap_nr_bits; 31 32 /* Total number of bits for the whole bitmap */ 33 unsigned int total_nr_bits; 34 35 /* 36 * *_offset indicates where the bitmap starts, the length is always 37 * @bitmap_size, which is calculated from PAGE_SIZE / sectorsize. 38 */ 39 unsigned int uptodate_offset; 40 unsigned int dirty_offset; 41 unsigned int writeback_offset; 42 unsigned int ordered_offset; 43 unsigned int checked_offset; 44 45 /* 46 * For locked bitmaps, normally it's subpage representation for folio 47 * Locked flag, but metadata is different: 48 * 49 * - Metadata doesn't really lock the folio 50 * It's just to prevent page::private get cleared before the last 51 * end_page_read(). 52 */ 53 unsigned int locked_offset; 54 }; 55 56 /* 57 * Structure to trace status of each sector inside a page, attached to 58 * page::private for both data and metadata inodes. 59 */ 60 struct btrfs_subpage { 61 /* Common members for both data and metadata pages */ 62 spinlock_t lock; 63 /* 64 * Both data and metadata needs to track how many readers are for the 65 * page. 66 * Data relies on @readers to unlock the page when last reader finished. 67 * While metadata doesn't need page unlock, it needs to prevent 68 * page::private get cleared before the last end_page_read(). 69 */ 70 atomic_t readers; 71 union { 72 /* 73 * Structures only used by metadata 74 * 75 * @eb_refs should only be operated under private_lock, as it 76 * manages whether the subpage can be detached. 77 */ 78 atomic_t eb_refs; 79 80 /* Structures only used by data */ 81 atomic_t writers; 82 }; 83 unsigned long bitmaps[]; 84 }; 85 86 enum btrfs_subpage_type { 87 BTRFS_SUBPAGE_METADATA, 88 BTRFS_SUBPAGE_DATA, 89 }; 90 91 bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct address_space *mapping); 92 93 void btrfs_init_subpage_info(struct btrfs_subpage_info *subpage_info, u32 sectorsize); 94 int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info, 95 struct folio *folio, enum btrfs_subpage_type type); 96 void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, struct folio *folio); 97 98 /* Allocate additional data where page represents more than one sector */ 99 struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info, 100 enum btrfs_subpage_type type); 101 void btrfs_free_subpage(struct btrfs_subpage *subpage); 102 103 void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio); 104 void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio); 105 106 void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info, 107 struct folio *folio, u64 start, u32 len); 108 void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info, 109 struct folio *folio, u64 start, u32 len); 110 111 int btrfs_folio_start_writer_lock(const struct btrfs_fs_info *fs_info, 112 struct folio *folio, u64 start, u32 len); 113 void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info, 114 struct folio *folio, u64 start, u32 len); 115 void btrfs_folio_set_writer_lock(const struct btrfs_fs_info *fs_info, 116 struct folio *folio, u64 start, u32 len); 117 bool btrfs_subpage_find_writer_locked(const struct btrfs_fs_info *fs_info, 118 struct folio *folio, u64 search_start, 119 u64 *found_start_ret, u32 *found_len_ret); 120 void btrfs_folio_end_all_writers(const struct btrfs_fs_info *fs_info, struct folio *folio); 121 122 /* 123 * Template for subpage related operations. 124 * 125 * btrfs_subpage_*() are for call sites where the folio has subpage attached and 126 * the range is ensured to be inside the folio's single page. 127 * 128 * btrfs_folio_*() are for call sites where the page can either be subpage 129 * specific or regular folios. The function will handle both cases. 130 * But the range still needs to be inside one single page. 131 * 132 * btrfs_folio_clamp_*() are similar to btrfs_folio_*(), except the range doesn't 133 * need to be inside the page. Those functions will truncate the range 134 * automatically. 135 */ 136 #define DECLARE_BTRFS_SUBPAGE_OPS(name) \ 137 void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \ 138 struct folio *folio, u64 start, u32 len); \ 139 void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \ 140 struct folio *folio, u64 start, u32 len); \ 141 bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \ 142 struct folio *folio, u64 start, u32 len); \ 143 void btrfs_folio_set_##name(const struct btrfs_fs_info *fs_info, \ 144 struct folio *folio, u64 start, u32 len); \ 145 void btrfs_folio_clear_##name(const struct btrfs_fs_info *fs_info, \ 146 struct folio *folio, u64 start, u32 len); \ 147 bool btrfs_folio_test_##name(const struct btrfs_fs_info *fs_info, \ 148 struct folio *folio, u64 start, u32 len); \ 149 void btrfs_folio_clamp_set_##name(const struct btrfs_fs_info *fs_info, \ 150 struct folio *folio, u64 start, u32 len); \ 151 void btrfs_folio_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \ 152 struct folio *folio, u64 start, u32 len); \ 153 bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info, \ 154 struct folio *folio, u64 start, u32 len); 155 156 DECLARE_BTRFS_SUBPAGE_OPS(uptodate); 157 DECLARE_BTRFS_SUBPAGE_OPS(dirty); 158 DECLARE_BTRFS_SUBPAGE_OPS(writeback); 159 DECLARE_BTRFS_SUBPAGE_OPS(ordered); 160 DECLARE_BTRFS_SUBPAGE_OPS(checked); 161 162 bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info, 163 struct folio *folio, u64 start, u32 len); 164 165 void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info, 166 struct folio *folio, u64 start, u32 len); 167 void btrfs_folio_unlock_writer(struct btrfs_fs_info *fs_info, 168 struct folio *folio, u64 start, u32 len); 169 void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info, 170 struct folio *folio, u64 start, u32 len); 171 172 #endif 173