diff options
Diffstat (limited to 'fs/btrfs/subpage.h')
| -rw-r--r-- | fs/btrfs/subpage.h | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h index fdcadc5193c1..386246a7770f 100644 --- a/fs/btrfs/subpage.h +++ b/fs/btrfs/subpage.h @@ -12,6 +12,39 @@ #define BTRFS_SUBPAGE_BITMAP_SIZE 16 /* + * 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; +}; + +/* * Structure to trace status of each sector inside a page, attached to * page::private for both data and metadata inodes. */ @@ -53,6 +86,7 @@ enum btrfs_subpage_type { BTRFS_SUBPAGE_DATA, }; +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, |