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 */
27 * Structures only used by metadata
29 * @eb_refs should only be operated under private_lock, as it
30 * manages whether the subpage can be detached.
33 /* Structures only used by data */
40 enum btrfs_subpage_type {
41 BTRFS_SUBPAGE_METADATA,
45 int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
46 struct page *page, enum btrfs_subpage_type type);
47 void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info,
50 /* Allocate additional data where page represents more than one sector */
51 int btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
52 struct btrfs_subpage **ret,
53 enum btrfs_subpage_type type);
54 void btrfs_free_subpage(struct btrfs_subpage *subpage);
56 void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info,
58 void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info,
61 void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
62 struct page *page, u64 start, u32 len);
63 void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
64 struct page *page, u64 start, u32 len);
67 * Template for subpage related operations.
69 * btrfs_subpage_*() are for call sites where the page has subpage attached and
70 * the range is ensured to be inside the page.
72 * btrfs_page_*() are for call sites where the page can either be subpage
73 * specific or regular page. The function will handle both cases.
74 * But the range still needs to be inside the page.
76 #define DECLARE_BTRFS_SUBPAGE_OPS(name) \
77 void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \
78 struct page *page, u64 start, u32 len); \
79 void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \
80 struct page *page, u64 start, u32 len); \
81 bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \
82 struct page *page, u64 start, u32 len); \
83 void btrfs_page_set_##name(const struct btrfs_fs_info *fs_info, \
84 struct page *page, u64 start, u32 len); \
85 void btrfs_page_clear_##name(const struct btrfs_fs_info *fs_info, \
86 struct page *page, u64 start, u32 len); \
87 bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info, \
88 struct page *page, u64 start, u32 len);
90 DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
91 DECLARE_BTRFS_SUBPAGE_OPS(error);
92 DECLARE_BTRFS_SUBPAGE_OPS(dirty);
93 DECLARE_BTRFS_SUBPAGE_OPS(writeback);
95 bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
96 struct page *page, u64 start, u32 len);