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/error/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 /- error_offset /- dirty_offset 17 * | | | 18 * v v v 19 * |u|u|u|u|........|u|u|e|e|.......|e|e| ... |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 error_offset; 36 unsigned int dirty_offset; 37 unsigned int writeback_offset; 38 unsigned int ordered_offset; 39 unsigned int checked_offset; 40 }; 41 42 /* 43 * Structure to trace status of each sector inside a page, attached to 44 * page::private for both data and metadata inodes. 45 */ 46 struct btrfs_subpage { 47 /* Common members for both data and metadata pages */ 48 spinlock_t lock; 49 /* 50 * Both data and metadata needs to track how many readers are for the 51 * page. 52 * Data relies on @readers to unlock the page when last reader finished. 53 * While metadata doesn't need page unlock, it needs to prevent 54 * page::private get cleared before the last end_page_read(). 55 */ 56 atomic_t readers; 57 union { 58 /* 59 * Structures only used by metadata 60 * 61 * @eb_refs should only be operated under private_lock, as it 62 * manages whether the subpage can be detached. 63 */ 64 atomic_t eb_refs; 65 66 /* Structures only used by data */ 67 atomic_t writers; 68 }; 69 unsigned long bitmaps[]; 70 }; 71 72 enum btrfs_subpage_type { 73 BTRFS_SUBPAGE_METADATA, 74 BTRFS_SUBPAGE_DATA, 75 }; 76 77 bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct page *page); 78 79 void btrfs_init_subpage_info(struct btrfs_subpage_info *subpage_info, u32 sectorsize); 80 int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info, 81 struct page *page, enum btrfs_subpage_type type); 82 void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, 83 struct page *page); 84 85 /* Allocate additional data where page represents more than one sector */ 86 struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info, 87 enum btrfs_subpage_type type); 88 void btrfs_free_subpage(struct btrfs_subpage *subpage); 89 90 void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info, 91 struct page *page); 92 void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info, 93 struct page *page); 94 95 void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info, 96 struct page *page, u64 start, u32 len); 97 void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info, 98 struct page *page, u64 start, u32 len); 99 100 void btrfs_subpage_start_writer(const struct btrfs_fs_info *fs_info, 101 struct page *page, u64 start, u32 len); 102 bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info, 103 struct page *page, u64 start, u32 len); 104 int btrfs_page_start_writer_lock(const struct btrfs_fs_info *fs_info, 105 struct page *page, u64 start, u32 len); 106 void btrfs_page_end_writer_lock(const struct btrfs_fs_info *fs_info, 107 struct page *page, u64 start, u32 len); 108 109 /* 110 * Template for subpage related operations. 111 * 112 * btrfs_subpage_*() are for call sites where the page has subpage attached and 113 * the range is ensured to be inside the page. 114 * 115 * btrfs_page_*() are for call sites where the page can either be subpage 116 * specific or regular page. The function will handle both cases. 117 * But the range still needs to be inside the page. 118 * 119 * btrfs_page_clamp_*() are similar to btrfs_page_*(), except the range doesn't 120 * need to be inside the page. Those functions will truncate the range 121 * automatically. 122 */ 123 #define DECLARE_BTRFS_SUBPAGE_OPS(name) \ 124 void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \ 125 struct page *page, u64 start, u32 len); \ 126 void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \ 127 struct page *page, u64 start, u32 len); \ 128 bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \ 129 struct page *page, u64 start, u32 len); \ 130 void btrfs_page_set_##name(const struct btrfs_fs_info *fs_info, \ 131 struct page *page, u64 start, u32 len); \ 132 void btrfs_page_clear_##name(const struct btrfs_fs_info *fs_info, \ 133 struct page *page, u64 start, u32 len); \ 134 bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info, \ 135 struct page *page, u64 start, u32 len); \ 136 void btrfs_page_clamp_set_##name(const struct btrfs_fs_info *fs_info, \ 137 struct page *page, u64 start, u32 len); \ 138 void btrfs_page_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \ 139 struct page *page, u64 start, u32 len); \ 140 bool btrfs_page_clamp_test_##name(const struct btrfs_fs_info *fs_info, \ 141 struct page *page, u64 start, u32 len); 142 143 DECLARE_BTRFS_SUBPAGE_OPS(uptodate); 144 DECLARE_BTRFS_SUBPAGE_OPS(error); 145 DECLARE_BTRFS_SUBPAGE_OPS(dirty); 146 DECLARE_BTRFS_SUBPAGE_OPS(writeback); 147 DECLARE_BTRFS_SUBPAGE_OPS(ordered); 148 DECLARE_BTRFS_SUBPAGE_OPS(checked); 149 150 bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info, 151 struct page *page, u64 start, u32 len); 152 153 void btrfs_page_assert_not_dirty(const struct btrfs_fs_info *fs_info, 154 struct page *page); 155 void btrfs_page_unlock_writer(struct btrfs_fs_info *fs_info, struct page *page, 156 u64 start, u32 len); 157 158 #endif 159