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/error/dirty/writeback/ordered bitmaps into
14 * This structure records how they are organized in the bitmap:
16 * /- uptodate_offset /- error_offset /- dirty_offset
19 * |u|u|u|u|........|u|u|e|e|.......|e|e| ... |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 error_offset;
36 unsigned int dirty_offset;
37 unsigned int writeback_offset;
38 unsigned int ordered_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 void btrfs_init_subpage_info(struct btrfs_subpage_info *subpage_info, u32 sectorsize);
77 int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
78 struct page *page, enum btrfs_subpage_type type);
79 void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info,
82 /* Allocate additional data where page represents more than one sector */
83 struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
84 enum btrfs_subpage_type type);
85 void btrfs_free_subpage(struct btrfs_subpage *subpage);
87 void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info,
89 void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info,
92 void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
93 struct page *page, u64 start, u32 len);
94 void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
95 struct page *page, u64 start, u32 len);
97 void btrfs_subpage_start_writer(const struct btrfs_fs_info *fs_info,
98 struct page *page, u64 start, u32 len);
99 bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info,
100 struct page *page, u64 start, u32 len);
101 int btrfs_page_start_writer_lock(const struct btrfs_fs_info *fs_info,
102 struct page *page, u64 start, u32 len);
103 void btrfs_page_end_writer_lock(const struct btrfs_fs_info *fs_info,
104 struct page *page, u64 start, u32 len);
107 * Template for subpage related operations.
109 * btrfs_subpage_*() are for call sites where the page has subpage attached and
110 * the range is ensured to be inside the page.
112 * btrfs_page_*() are for call sites where the page can either be subpage
113 * specific or regular page. The function will handle both cases.
114 * But the range still needs to be inside the page.
116 * btrfs_page_clamp_*() are similar to btrfs_page_*(), except the range doesn't
117 * need to be inside the page. Those functions will truncate the range
120 #define DECLARE_BTRFS_SUBPAGE_OPS(name) \
121 void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \
122 struct page *page, u64 start, u32 len); \
123 void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \
124 struct page *page, u64 start, u32 len); \
125 bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \
126 struct page *page, u64 start, u32 len); \
127 void btrfs_page_set_##name(const struct btrfs_fs_info *fs_info, \
128 struct page *page, u64 start, u32 len); \
129 void btrfs_page_clear_##name(const struct btrfs_fs_info *fs_info, \
130 struct page *page, u64 start, u32 len); \
131 bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info, \
132 struct page *page, u64 start, u32 len); \
133 void btrfs_page_clamp_set_##name(const struct btrfs_fs_info *fs_info, \
134 struct page *page, u64 start, u32 len); \
135 void btrfs_page_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \
136 struct page *page, u64 start, u32 len); \
137 bool btrfs_page_clamp_test_##name(const struct btrfs_fs_info *fs_info, \
138 struct page *page, u64 start, u32 len);
140 DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
141 DECLARE_BTRFS_SUBPAGE_OPS(error);
142 DECLARE_BTRFS_SUBPAGE_OPS(dirty);
143 DECLARE_BTRFS_SUBPAGE_OPS(writeback);
144 DECLARE_BTRFS_SUBPAGE_OPS(ordered);
146 bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
147 struct page *page, u64 start, u32 len);
149 void btrfs_page_assert_not_dirty(const struct btrfs_fs_info *fs_info,