diff options
Diffstat (limited to 'fs/btrfs/subpage.h')
| -rw-r--r-- | fs/btrfs/subpage.h | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h new file mode 100644 index 000000000000..0e80ad336904 --- /dev/null +++ b/fs/btrfs/subpage.h @@ -0,0 +1,158 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef BTRFS_SUBPAGE_H +#define BTRFS_SUBPAGE_H + +#include <linux/spinlock.h> + +/* + * Extra info for subpapge bitmap. + * + * For subpage we pack all uptodate/error/dirty/writeback/ordered bitmaps into + * one larger bitmap. + * + * This structure records how they are organized in the bitmap: + * + * /- uptodate_offset /- error_offset /- dirty_offset + * | | | + * v v v + * |u|u|u|u|........|u|u|e|e|.......|e|e| ... |o|o| + * |<- bitmap_nr_bits ->| + * |<--------------- total_nr_bits ---------------->| + */ +struct btrfs_subpage_info { + /* Number of bits for each bitmap */ + unsigned int bitmap_nr_bits; + + /* Total number of bits for the whole bitmap */ + unsigned int total_nr_bits; + + /* + * *_start indicates where the bitmap starts, the length is always + * @bitmap_size, which is calculated from PAGE_SIZE / sectorsize. + */ + unsigned int uptodate_offset; + unsigned int error_offset; + unsigned int dirty_offset; + unsigned int writeback_offset; + unsigned int ordered_offset; + unsigned int checked_offset; +}; + +/* + * Structure to trace status of each sector inside a page, attached to + * page::private for both data and metadata inodes. + */ +struct btrfs_subpage { + /* Common members for both data and metadata pages */ + spinlock_t lock; + /* + * Both data and metadata needs to track how many readers are for the + * page. + * Data relies on @readers to unlock the page when last reader finished. + * While metadata doesn't need page unlock, it needs to prevent + * page::private get cleared before the last end_page_read(). + */ + atomic_t readers; + union { + /* + * Structures only used by metadata + * + * @eb_refs should only be operated under private_lock, as it + * manages whether the subpage can be detached. + */ + atomic_t eb_refs; + + /* Structures only used by data */ + atomic_t writers; + }; + unsigned long bitmaps[]; +}; + +enum btrfs_subpage_type { + BTRFS_SUBPAGE_METADATA, + BTRFS_SUBPAGE_DATA, +}; + +bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct page *page); + +void btrfs_init_subpage_info(struct btrfs_subpage_info *subpage_info, u32 sectorsize); +int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info, + struct page *page, enum btrfs_subpage_type type); +void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, + struct page *page); + +/* Allocate additional data where page represents more than one sector */ +struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info, + enum btrfs_subpage_type type); +void btrfs_free_subpage(struct btrfs_subpage *subpage); + +void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info, + struct page *page); +void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info, + struct page *page); + +void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info, + struct page *page, u64 start, u32 len); +void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info, + struct page *page, u64 start, u32 len); + +void btrfs_subpage_start_writer(const struct btrfs_fs_info *fs_info, + struct page *page, u64 start, u32 len); +bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info, + struct page *page, u64 start, u32 len); +int btrfs_page_start_writer_lock(const struct btrfs_fs_info *fs_info, + struct page *page, u64 start, u32 len); +void btrfs_page_end_writer_lock(const struct btrfs_fs_info *fs_info, + struct page *page, u64 start, u32 len); + +/* + * Template for subpage related operations. + * + * btrfs_subpage_*() are for call sites where the page has subpage attached and + * the range is ensured to be inside the page. + * + * btrfs_page_*() are for call sites where the page can either be subpage + * specific or regular page. The function will handle both cases. + * But the range still needs to be inside the page. + * + * btrfs_page_clamp_*() are similar to btrfs_page_*(), except the range doesn't + * need to be inside the page. Those functions will truncate the range + * automatically. + */ +#define DECLARE_BTRFS_SUBPAGE_OPS(name) \ +void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \ + struct page *page, u64 start, u32 len); \ +void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \ + struct page *page, u64 start, u32 len); \ +bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \ + struct page *page, u64 start, u32 len); \ +void btrfs_page_set_##name(const struct btrfs_fs_info *fs_info, \ + struct page *page, u64 start, u32 len); \ +void btrfs_page_clear_##name(const struct btrfs_fs_info *fs_info, \ + struct page *page, u64 start, u32 len); \ +bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info, \ + struct page *page, u64 start, u32 len); \ +void btrfs_page_clamp_set_##name(const struct btrfs_fs_info *fs_info, \ + struct page *page, u64 start, u32 len); \ +void btrfs_page_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \ + struct page *page, u64 start, u32 len); \ +bool btrfs_page_clamp_test_##name(const struct btrfs_fs_info *fs_info, \ + struct page *page, u64 start, u32 len); + +DECLARE_BTRFS_SUBPAGE_OPS(uptodate); +DECLARE_BTRFS_SUBPAGE_OPS(error); +DECLARE_BTRFS_SUBPAGE_OPS(dirty); +DECLARE_BTRFS_SUBPAGE_OPS(writeback); +DECLARE_BTRFS_SUBPAGE_OPS(ordered); +DECLARE_BTRFS_SUBPAGE_OPS(checked); + +bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info, + struct page *page, u64 start, u32 len); + +void btrfs_page_assert_not_dirty(const struct btrfs_fs_info *fs_info, + struct page *page); +void btrfs_page_unlock_writer(struct btrfs_fs_info *fs_info, struct page *page, + u64 start, u32 len); + +#endif |