1 /* SPDX-License-Identifier: GPL-2.0 */
3 #ifndef BTRFS_SUBPAGE_H
4 #define BTRFS_SUBPAGE_H
6 #include <linux/spinlock.h>
9 * Extra info for subpapge bitmap.
11 * For subpage we pack all uptodate/dirty/writeback/ordered bitmaps into
14 * This structure records how they are organized in the bitmap:
16 * /- uptodate_offset /- dirty_offset /- ordered_offset
19 * |u|u|u|u|........|u|u|d|d|.......|d|d|o|o|.......|o|o|
20 * |<- bitmap_nr_bits ->|
21 * |<----------------- total_nr_bits ------------------>|
23 struct btrfs_subpage_info {
24 /* Number of bits for each bitmap */
25 unsigned int bitmap_nr_bits;
27 /* Total number of bits for the whole bitmap */
28 unsigned int total_nr_bits;
31 * *_start indicates where the bitmap starts, the length is always
32 * @bitmap_size, which is calculated from PAGE_SIZE / sectorsize.
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;
42 * Structure to trace status of each sector inside a page, attached to
43 * page::private for both data and metadata inodes.
45 struct btrfs_subpage {
46 /* Common members for both data and metadata pages */
49 * Both data and metadata needs to track how many readers are for the
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().
58 * Structures only used by metadata
60 * @eb_refs should only be operated under private_lock, as it
61 * manages whether the subpage can be detached.
65 /* Structures only used by data */
68 unsigned long bitmaps[];
71 enum btrfs_subpage_type {
72 BTRFS_SUBPAGE_METADATA,
76 bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct address_space *mapping);
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 folio *folio, enum btrfs_subpage_type type);
81 void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, struct folio *folio);
83 /* Allocate additional data where page represents more than one sector */
84 struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
85 enum btrfs_subpage_type type);
86 void btrfs_free_subpage(struct btrfs_subpage *subpage);
88 void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
89 void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
91 void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
92 struct folio *folio, u64 start, u32 len);
93 void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
94 struct folio *folio, u64 start, u32 len);
96 void btrfs_subpage_start_writer(const struct btrfs_fs_info *fs_info,
97 struct folio *folio, u64 start, u32 len);
98 bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info,
99 struct folio *folio, u64 start, u32 len);
100 int btrfs_folio_start_writer_lock(const struct btrfs_fs_info *fs_info,
101 struct folio *folio, u64 start, u32 len);
102 void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info,
103 struct folio *folio, u64 start, u32 len);
106 * Template for subpage related operations.
108 * btrfs_subpage_*() are for call sites where the folio has subpage attached and
109 * the range is ensured to be inside the folio's single page.
111 * btrfs_folio_*() are for call sites where the page can either be subpage
112 * specific or regular folios. The function will handle both cases.
113 * But the range still needs to be inside one single page.
115 * btrfs_folio_clamp_*() are similar to btrfs_folio_*(), except the range doesn't
116 * need to be inside the page. Those functions will truncate the range
119 #define DECLARE_BTRFS_SUBPAGE_OPS(name) \
120 void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \
121 struct folio *folio, u64 start, u32 len); \
122 void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \
123 struct folio *folio, u64 start, u32 len); \
124 bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \
125 struct folio *folio, u64 start, u32 len); \
126 void btrfs_folio_set_##name(const struct btrfs_fs_info *fs_info, \
127 struct folio *folio, u64 start, u32 len); \
128 void btrfs_folio_clear_##name(const struct btrfs_fs_info *fs_info, \
129 struct folio *folio, u64 start, u32 len); \
130 bool btrfs_folio_test_##name(const struct btrfs_fs_info *fs_info, \
131 struct folio *folio, u64 start, u32 len); \
132 void btrfs_folio_clamp_set_##name(const struct btrfs_fs_info *fs_info, \
133 struct folio *folio, u64 start, u32 len); \
134 void btrfs_folio_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \
135 struct folio *folio, u64 start, u32 len); \
136 bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info, \
137 struct folio *folio, u64 start, u32 len);
139 DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
140 DECLARE_BTRFS_SUBPAGE_OPS(dirty);
141 DECLARE_BTRFS_SUBPAGE_OPS(writeback);
142 DECLARE_BTRFS_SUBPAGE_OPS(ordered);
143 DECLARE_BTRFS_SUBPAGE_OPS(checked);
145 bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
146 struct folio *folio, u64 start, u32 len);
148 void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info, struct folio *folio);
149 void btrfs_folio_unlock_writer(struct btrfs_fs_info *fs_info,
150 struct folio *folio, u64 start, u32 len);
151 void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info,
152 struct folio *folio, u64 start, u32 len);