1 /* SPDX-License-Identifier: GPL-2.0 */
3 #ifndef BTRFS_SUBPAGE_H
4 #define BTRFS_SUBPAGE_H
6 #include <linux/spinlock.h>
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.
12 #define BTRFS_SUBPAGE_BITMAP_SIZE 16
15 * Structure to trace status of each sector inside a page, attached to
16 * page::private for both data and metadata inodes.
18 struct btrfs_subpage {
19 /* Common members for both data and metadata pages */
26 * Both data and metadata needs to track how many readers are for the
28 * Data relies on @readers to unlock the page when last reader finished.
29 * While metadata doesn't need page unlock, it needs to prevent
30 * page::private get cleared before the last end_page_read().
35 * Structures only used by metadata
37 * @eb_refs should only be operated under private_lock, as it
38 * manages whether the subpage can be detached.
41 /* Structures only used by data */
45 /* Tracke pending ordered extent in this sector */
51 enum btrfs_subpage_type {
52 BTRFS_SUBPAGE_METADATA,
56 int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
57 struct page *page, enum btrfs_subpage_type type);
58 void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info,
61 /* Allocate additional data where page represents more than one sector */
62 int btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
63 struct btrfs_subpage **ret,
64 enum btrfs_subpage_type type);
65 void btrfs_free_subpage(struct btrfs_subpage *subpage);
67 void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info,
69 void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info,
72 void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
73 struct page *page, u64 start, u32 len);
74 void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
75 struct page *page, u64 start, u32 len);
77 void btrfs_subpage_start_writer(const struct btrfs_fs_info *fs_info,
78 struct page *page, u64 start, u32 len);
79 bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info,
80 struct page *page, u64 start, u32 len);
81 int btrfs_page_start_writer_lock(const struct btrfs_fs_info *fs_info,
82 struct page *page, u64 start, u32 len);
83 void btrfs_page_end_writer_lock(const struct btrfs_fs_info *fs_info,
84 struct page *page, u64 start, u32 len);
87 * Template for subpage related operations.
89 * btrfs_subpage_*() are for call sites where the page has subpage attached and
90 * the range is ensured to be inside the page.
92 * btrfs_page_*() are for call sites where the page can either be subpage
93 * specific or regular page. The function will handle both cases.
94 * But the range still needs to be inside the page.
96 * btrfs_page_clamp_*() are similar to btrfs_page_*(), except the range doesn't
97 * need to be inside the page. Those functions will truncate the range
100 #define DECLARE_BTRFS_SUBPAGE_OPS(name) \
101 void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \
102 struct page *page, u64 start, u32 len); \
103 void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \
104 struct page *page, u64 start, u32 len); \
105 bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \
106 struct page *page, u64 start, u32 len); \
107 void btrfs_page_set_##name(const struct btrfs_fs_info *fs_info, \
108 struct page *page, u64 start, u32 len); \
109 void btrfs_page_clear_##name(const struct btrfs_fs_info *fs_info, \
110 struct page *page, u64 start, u32 len); \
111 bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info, \
112 struct page *page, u64 start, u32 len); \
113 void btrfs_page_clamp_set_##name(const struct btrfs_fs_info *fs_info, \
114 struct page *page, u64 start, u32 len); \
115 void btrfs_page_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \
116 struct page *page, u64 start, u32 len); \
117 bool btrfs_page_clamp_test_##name(const struct btrfs_fs_info *fs_info, \
118 struct page *page, u64 start, u32 len);
120 DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
121 DECLARE_BTRFS_SUBPAGE_OPS(error);
122 DECLARE_BTRFS_SUBPAGE_OPS(dirty);
123 DECLARE_BTRFS_SUBPAGE_OPS(writeback);
124 DECLARE_BTRFS_SUBPAGE_OPS(ordered);
126 bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
127 struct page *page, u64 start, u32 len);
129 void btrfs_page_assert_not_dirty(const struct btrfs_fs_info *fs_info,