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cac06d84 QW |
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 | * Maximum page size we support is 64K, minimum sector size is 4K, u16 bitmap | |
10 | * is sufficient. Regular bitmap_* is not used due to size reasons. | |
11 | */ | |
12 | #define BTRFS_SUBPAGE_BITMAP_SIZE 16 | |
13 | ||
14 | /* | |
15 | * Structure to trace status of each sector inside a page, attached to | |
16 | * page::private for both data and metadata inodes. | |
17 | */ | |
18 | struct btrfs_subpage { | |
19 | /* Common members for both data and metadata pages */ | |
20 | spinlock_t lock; | |
a1d767c1 | 21 | u16 uptodate_bitmap; |
03a816b3 | 22 | u16 error_bitmap; |
760f991f | 23 | union { |
8ff8466d QW |
24 | /* |
25 | * Structures only used by metadata | |
26 | * | |
27 | * @eb_refs should only be operated under private_lock, as it | |
28 | * manages whether the subpage can be detached. | |
29 | */ | |
30 | atomic_t eb_refs; | |
760f991f | 31 | /* Structures only used by data */ |
92082d40 QW |
32 | struct { |
33 | atomic_t readers; | |
34 | }; | |
760f991f | 35 | }; |
cac06d84 QW |
36 | }; |
37 | ||
38 | enum btrfs_subpage_type { | |
39 | BTRFS_SUBPAGE_METADATA, | |
40 | BTRFS_SUBPAGE_DATA, | |
41 | }; | |
42 | ||
43 | int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info, | |
44 | struct page *page, enum btrfs_subpage_type type); | |
45 | void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, | |
46 | struct page *page); | |
47 | ||
760f991f QW |
48 | /* Allocate additional data where page represents more than one sector */ |
49 | int btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info, | |
50 | struct btrfs_subpage **ret, | |
51 | enum btrfs_subpage_type type); | |
52 | void btrfs_free_subpage(struct btrfs_subpage *subpage); | |
53 | ||
8ff8466d QW |
54 | void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info, |
55 | struct page *page); | |
56 | void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info, | |
57 | struct page *page); | |
58 | ||
92082d40 QW |
59 | void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info, |
60 | struct page *page, u64 start, u32 len); | |
61 | void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info, | |
62 | struct page *page, u64 start, u32 len); | |
63 | ||
a1d767c1 QW |
64 | /* |
65 | * Template for subpage related operations. | |
66 | * | |
67 | * btrfs_subpage_*() are for call sites where the page has subpage attached and | |
68 | * the range is ensured to be inside the page. | |
69 | * | |
70 | * btrfs_page_*() are for call sites where the page can either be subpage | |
71 | * specific or regular page. The function will handle both cases. | |
72 | * But the range still needs to be inside the page. | |
73 | */ | |
74 | #define DECLARE_BTRFS_SUBPAGE_OPS(name) \ | |
75 | void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \ | |
76 | struct page *page, u64 start, u32 len); \ | |
77 | void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \ | |
78 | struct page *page, u64 start, u32 len); \ | |
79 | bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \ | |
80 | struct page *page, u64 start, u32 len); \ | |
81 | void btrfs_page_set_##name(const struct btrfs_fs_info *fs_info, \ | |
82 | struct page *page, u64 start, u32 len); \ | |
83 | void btrfs_page_clear_##name(const struct btrfs_fs_info *fs_info, \ | |
84 | struct page *page, u64 start, u32 len); \ | |
85 | bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info, \ | |
86 | struct page *page, u64 start, u32 len); | |
87 | ||
88 | DECLARE_BTRFS_SUBPAGE_OPS(uptodate); | |
03a816b3 | 89 | DECLARE_BTRFS_SUBPAGE_OPS(error); |
a1d767c1 | 90 | |
cac06d84 | 91 | #endif |