f2fs: parameterize node helpers and macros

In gang-lookup loops such as last_fsync_dnode(), f2fs_sync_node_pages(),
and f2fs_fsync_node_pages(), candidate dirty node folios returned by
filemap_get_folios_tag() are inspected and filtered before acquiring
their folio locks:
- IS_DNODE
- is_cold_node
- ino_of_node
- ofs_of_node (called by IS_DNODE)

These helpers previously relied on F2FS_F_SB(folio) which dereferences
folio->mapping to obtain sbi. This can suffer a race condition with
concurrent node truncation, causing a NULL pointer dereference panic:

Thread A                            Thread B
- f2fs_sync_node_pages
  - filemap_get_folios_tag
                                    - truncate_node
                                      - invalidate_mapping_pages
                                        - filemap_remove_folio
                                          - folio->mapping = NULL
- IS_DNODE
  - F2FS_F_SB
    - folio->mapping->host (panic)

To resolve this race condition, pass struct f2fs_sb_info *sbi explicitly
to these helpers.

All these helpers fundamentally rely on F2FS_NODE_FOOTER(), which
dynamically locates the node footer at:
folio_address(folio) + F2FS_BLKSIZE(sbi) - sizeof(struct node_footer).
Consequently, F2FS_NODE_FOOTER() and its direct sibling footer accessors:
- IS_INODE
- nid_of_node
- cpver_of_node
- next_blkaddr_of_node
are also parameterized with struct f2fs_sb_info *sbi.

In get_dnode_base() and get_dnode_addr(), derive sbi safely via
`inode ? F2FS_I_SB(inode) : F2FS_F_SB(node_folio)` to support callers
passing NULL inode (e.g. is_alive()).

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

0 files changed, 0 insertions, 0 deletions