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