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 8 /* 9 * Extra info for subpapge bitmap. 10 * 11 * For subpage we pack all uptodate/dirty/writeback/ordered bitmaps into 12 * one larger bitmap. 13 * 14 * This structure records how they are organized in the bitmap: 15 * 16 * /- uptodate_offset /- dirty_offset /- ordered_offset 17 * | | | 18 * v v v 19 * |u|u|u|u|........|u|u|d|d|.......|d|d|o|o|.......|o|o| 20 * |<- bitmap_nr_bits ->| 21 * |<----------------- total_nr_bits ------------------>| 22 */ 23 struct btrfs_subpage_info { 24 /* Number of bits for each bitmap */ 25 unsigned int bitmap_nr_bits; 26 27 /* Total number of bits for the whole bitmap */ 28 unsigned int total_nr_bits; 29 30 /* 31 * *_start indicates where the bitmap starts, the length is always 32 * @bitmap_size, which is calculated from PAGE_SIZE / sectorsize. 33 */ 34 unsigned int uptodate_offset; 35 unsigned int dirty_offset; 36 unsigned int writeback_offset; 37 unsigned int ordered_offset; 38 unsigned int checked_offset; 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 bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct page *page); 77 78 void btrfs_init_subpage_info(struct btrfs_subpage_info *subpage_info, u32 sectorsize); 79 int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info, 80 struct page *page, enum btrfs_subpage_type type); 81 void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, 82 struct page *page); 83 84 /* Allocate additional data where page represents more than one sector */ 85 struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info, 86 enum btrfs_subpage_type type); 87 void btrfs_free_subpage(struct btrfs_subpage *subpage); 88 89 void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info, 90 struct page *page); 91 void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info, 92 struct page *page); 93 94 void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info, 95 struct page *page, u64 start, u32 len); 96 void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info, 97 struct page *page, u64 start, u32 len); 98 99 void btrfs_subpage_start_writer(const struct btrfs_fs_info *fs_info, 100 struct page *page, u64 start, u32 len); 101 bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info, 102 struct page *page, u64 start, u32 len); 103 int btrfs_page_start_writer_lock(const struct btrfs_fs_info *fs_info, 104 struct page *page, u64 start, u32 len); 105 void btrfs_page_end_writer_lock(const struct btrfs_fs_info *fs_info, 106 struct page *page, u64 start, u32 len); 107 108 /* 109 * Template for subpage related operations. 110 * 111 * btrfs_subpage_*() are for call sites where the page has subpage attached and 112 * the range is ensured to be inside the page. 113 * 114 * btrfs_page_*() are for call sites where the page can either be subpage 115 * specific or regular page. The function will handle both cases. 116 * But the range still needs to be inside the page. 117 * 118 * btrfs_page_clamp_*() are similar to btrfs_page_*(), except the range doesn't 119 * need to be inside the page. Those functions will truncate the range 120 * automatically. 121 */ 122 #define DECLARE_BTRFS_SUBPAGE_OPS(name) \ 123 void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \ 124 struct page *page, u64 start, u32 len); \ 125 void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \ 126 struct page *page, u64 start, u32 len); \ 127 bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \ 128 struct page *page, u64 start, u32 len); \ 129 void btrfs_page_set_##name(const struct btrfs_fs_info *fs_info, \ 130 struct page *page, u64 start, u32 len); \ 131 void btrfs_page_clear_##name(const struct btrfs_fs_info *fs_info, \ 132 struct page *page, u64 start, u32 len); \ 133 bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info, \ 134 struct page *page, u64 start, u32 len); \ 135 void btrfs_page_clamp_set_##name(const struct btrfs_fs_info *fs_info, \ 136 struct page *page, u64 start, u32 len); \ 137 void btrfs_page_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \ 138 struct page *page, u64 start, u32 len); \ 139 bool btrfs_page_clamp_test_##name(const struct btrfs_fs_info *fs_info, \ 140 struct page *page, u64 start, u32 len); 141 142 DECLARE_BTRFS_SUBPAGE_OPS(uptodate); 143 DECLARE_BTRFS_SUBPAGE_OPS(dirty); 144 DECLARE_BTRFS_SUBPAGE_OPS(writeback); 145 DECLARE_BTRFS_SUBPAGE_OPS(ordered); 146 DECLARE_BTRFS_SUBPAGE_OPS(checked); 147 148 bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info, 149 struct page *page, u64 start, u32 len); 150 151 void btrfs_page_assert_not_dirty(const struct btrfs_fs_info *fs_info, 152 struct page *page); 153 void btrfs_page_unlock_writer(struct btrfs_fs_info *fs_info, struct page *page, 154 u64 start, u32 len); 155 void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info, 156 struct page *page, u64 start, u32 len); 157 158 #endif 159