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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 */
23struct 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 */
45struct 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
71enum btrfs_subpage_type {
72 BTRFS_SUBPAGE_METADATA,
73 BTRFS_SUBPAGE_DATA,
74};
75
76bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct address_space *mapping);
77
78void btrfs_init_subpage_info(struct btrfs_subpage_info *subpage_info, u32 sectorsize);
79int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
80 struct folio *folio, enum btrfs_subpage_type type);
81void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, struct folio *folio);
82
83/* Allocate additional data where page represents more than one sector */
84struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
85 enum btrfs_subpage_type type);
86void btrfs_free_subpage(struct btrfs_subpage *subpage);
87
88void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
89void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
90
91void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
92 struct folio *folio, u64 start, u32 len);
93void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
94 struct folio *folio, u64 start, u32 len);
95
96void btrfs_subpage_start_writer(const struct btrfs_fs_info *fs_info,
97 struct folio *folio, u64 start, u32 len);
98bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info,
99 struct folio *folio, u64 start, u32 len);
100int btrfs_folio_start_writer_lock(const struct btrfs_fs_info *fs_info,
101 struct folio *folio, u64 start, u32 len);
102void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info,
103 struct folio *folio, u64 start, u32 len);
104
105/*
106 * Template for subpage related operations.
107 *
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.
110 *
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.
114 *
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
117 * automatically.
118 */
119#define DECLARE_BTRFS_SUBPAGE_OPS(name) \
120void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \
121 struct folio *folio, u64 start, u32 len); \
122void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \
123 struct folio *folio, u64 start, u32 len); \
124bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \
125 struct folio *folio, u64 start, u32 len); \
126void btrfs_folio_set_##name(const struct btrfs_fs_info *fs_info, \
127 struct folio *folio, u64 start, u32 len); \
128void btrfs_folio_clear_##name(const struct btrfs_fs_info *fs_info, \
129 struct folio *folio, u64 start, u32 len); \
130bool btrfs_folio_test_##name(const struct btrfs_fs_info *fs_info, \
131 struct folio *folio, u64 start, u32 len); \
132void btrfs_folio_clamp_set_##name(const struct btrfs_fs_info *fs_info, \
133 struct folio *folio, u64 start, u32 len); \
134void btrfs_folio_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \
135 struct folio *folio, u64 start, u32 len); \
136bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info, \
137 struct folio *folio, u64 start, u32 len);
138
139DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
140DECLARE_BTRFS_SUBPAGE_OPS(dirty);
141DECLARE_BTRFS_SUBPAGE_OPS(writeback);
142DECLARE_BTRFS_SUBPAGE_OPS(ordered);
143DECLARE_BTRFS_SUBPAGE_OPS(checked);
144
145bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
146 struct folio *folio, u64 start, u32 len);
147
148void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info, struct folio *folio);
149void btrfs_folio_unlock_writer(struct btrfs_fs_info *fs_info,
150 struct folio *folio, u64 start, u32 len);
151void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info,
152 struct folio *folio, u64 start, u32 len);
153
154#endif
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
9struct address_space;
10struct folio;
11struct 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 */
28struct 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 */
60struct 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
86enum btrfs_subpage_type {
87 BTRFS_SUBPAGE_METADATA,
88 BTRFS_SUBPAGE_DATA,
89};
90
91bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct address_space *mapping);
92
93void btrfs_init_subpage_info(struct btrfs_subpage_info *subpage_info, u32 sectorsize);
94int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
95 struct folio *folio, enum btrfs_subpage_type type);
96void 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 */
99struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
100 enum btrfs_subpage_type type);
101void btrfs_free_subpage(struct btrfs_subpage *subpage);
102
103void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
104void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
105
106void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
107 struct folio *folio, u64 start, u32 len);
108void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
109 struct folio *folio, u64 start, u32 len);
110
111int btrfs_folio_start_writer_lock(const struct btrfs_fs_info *fs_info,
112 struct folio *folio, u64 start, u32 len);
113void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info,
114 struct folio *folio, u64 start, u32 len);
115
116/*
117 * Template for subpage related operations.
118 *
119 * btrfs_subpage_*() are for call sites where the folio has subpage attached and
120 * the range is ensured to be inside the folio's single page.
121 *
122 * btrfs_folio_*() are for call sites where the page can either be subpage
123 * specific or regular folios. The function will handle both cases.
124 * But the range still needs to be inside one single page.
125 *
126 * btrfs_folio_clamp_*() are similar to btrfs_folio_*(), except the range doesn't
127 * need to be inside the page. Those functions will truncate the range
128 * automatically.
129 */
130#define DECLARE_BTRFS_SUBPAGE_OPS(name) \
131void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \
132 struct folio *folio, u64 start, u32 len); \
133void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \
134 struct folio *folio, u64 start, u32 len); \
135bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \
136 struct folio *folio, u64 start, u32 len); \
137void btrfs_folio_set_##name(const struct btrfs_fs_info *fs_info, \
138 struct folio *folio, u64 start, u32 len); \
139void btrfs_folio_clear_##name(const struct btrfs_fs_info *fs_info, \
140 struct folio *folio, u64 start, u32 len); \
141bool btrfs_folio_test_##name(const struct btrfs_fs_info *fs_info, \
142 struct folio *folio, u64 start, u32 len); \
143void btrfs_folio_clamp_set_##name(const struct btrfs_fs_info *fs_info, \
144 struct folio *folio, u64 start, u32 len); \
145void btrfs_folio_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \
146 struct folio *folio, u64 start, u32 len); \
147bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info, \
148 struct folio *folio, u64 start, u32 len);
149
150DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
151DECLARE_BTRFS_SUBPAGE_OPS(dirty);
152DECLARE_BTRFS_SUBPAGE_OPS(writeback);
153DECLARE_BTRFS_SUBPAGE_OPS(ordered);
154DECLARE_BTRFS_SUBPAGE_OPS(checked);
155
156bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
157 struct folio *folio, u64 start, u32 len);
158
159void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info, struct folio *folio);
160void btrfs_folio_unlock_writer(struct btrfs_fs_info *fs_info,
161 struct folio *folio, u64 start, u32 len);
162void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info,
163 struct folio *folio, u64 start, u32 len);
164
165#endif