相关数据结构
node manager
记录空闲块和数据位图，在内存中：
struct f2fs_nm_info {
block_t nat_blkaddr; /* base disk address of NAT */
nid_t max_nid; /* maximum possible node ids */
nid_t available_nids; /* # of available node ids */
nid_t next_scan_nid; /* the next nid to be scanned */
unsigned int ram_thresh; /* control the memory footprint */
unsigned int ra_nid_pages; /* # of nid pages to be readaheaded */
unsigned int dirty_nats_ratio; /* control dirty nats ratio threshold */
/* NAT cache management */
struct radix_tree_root nat_root;/* root of the nat entry cache */
struct radix_tree_root nat_set_root;/* root of the nat set cache */
struct rw_semaphore nat_tree_lock; /* protect nat_tree_lock */
struct list_head nat_entries; /* cached nat entry list (clean) */
spinlock_t nat_list_lock; /* protect clean nat entry list */
unsigned int nat_cnt; /* the # of cached nat entries */
unsigned int dirty_nat_cnt; /* total num of nat entries in set */
unsigned int nat_blocks; /* # of nat blocks */
/* free node ids management */
struct radix_tree_root free_nid_root;/* root of the free_nid cache */
struct list_head free_nid_list; /* list for free nids excluding preallocated nids */
unsigned int nid_cnt[MAX_NID_STATE]; /* the number of free node id */
spinlock_t nid_list_lock; /* protect nid lists ops */
struct mutex build_lock; /* lock for build free nids */
unsigned char **free_nid_bitmap;
unsigned char *nat_block_bitmap;
unsigned short *free_nid_count; /* free nid count of NAT block */
/* for checkpoint */
char *nat_bitmap; /* NAT bitmap pointer */
unsigned int nat_bits_blocks; /* # of nat bits blocks */
unsigned char *nat_bits; /* NAT bits blocks */
unsigned char *full_nat_bits; /* full NAT pages */
unsigned char *empty_nat_bits; /* empty NAT pages */
#ifdef CONFIG_F2FS_CHECK_FS
char *nat_bitmap_mir; /* NAT bitmap mirror */
#endif
int bitmap_size; /* bitmap size */
};
全局记录上述信息的sb_info
struct f2fs_sb_info {
struct super_block *sb; /* pointer to VFS super block */
struct proc_dir_entry *s_proc; /* proc entry */
struct f2fs_super_block *raw_super; /* raw super block pointer */
struct rw_semaphore sb_lock; /* lock for raw super block */
int valid_super_block; /* valid super block no */
unsigned long s_flag; /* flags for sbi */
struct mutex writepages; /* mutex for writepages() */
#ifdef CONFIG_BLK_DEV_ZONED
unsigned int blocks_per_blkz; /* F2FS blocks per zone */
unsigned int log_blocks_per_blkz; /* log2 F2FS blocks per zone */
#endif
/* for node-related operations */
struct f2fs_nm_info *nm_info; /* node manager */
struct inode *node_inode; /* cache node blocks */
-----
/* for segment-related operations */
struct f2fs_sm_info *sm_info; /* segment manager */
-----
/* for bio operations */
struct f2fs_bio_info *write_io[NR_PAGE_TYPE]; /* for write bios */
struct mutex wio_mutex[NR_PAGE_TYPE - 1][NR_TEMP_TYPE];
/* bio ordering for NODE/DATA */
/* keep migration IO order for LFS mode */
struct rw_semaphore io_order_lock;
mempool_t *write_io_dummy; /* Dummy pages */
理解blk/node的分配必须看懂的关键数据结构
nid: node id node id是inode内部对索引节点的编号，根据层次内逐渐递增，当前层次遍历完了之后会对后面的层次进行遍历递归。 相关的数据结构定义有：
/*
* f2fs assigns the following node offsets described as (num).
* N = NIDS_PER_BLOCK
*
* Inode block (0)
* |- direct node (1)
* |- direct node (2)
* |- indirect node (3)
* | `- direct node (4 => 4 + N - 1)
* |- indirect node (4 + N)
* | `- direct node (5 + N => 5 + 2N - 1)
* `- double indirect node (5 + 2N)
* `- indirect node (6 + 2N)
* `- direct node
* ......
* `- indirect node ((6 + 2N) + x(N + 1))
* `- direct node
* ......
* `- indirect node ((6 + 2N) + (N - 1)(N + 1))
* `- direct node
*/
static inline bool IS_DNODE(struct page *node_page)
{
unsigned int ofs = ofs_of_node(node_page);
if (f2fs_has_xattr_block(ofs))
return true;
if (ofs == 3 || ofs == 4 + NIDS_PER_BLOCK ||
ofs == 5 + 2 * NIDS_PER_BLOCK)
return false;
if (ofs >= 6 + 2 * NIDS_PER_BLOCK) {
ofs -= 6 + 2 * NIDS_PER_BLOCK;
if (!((long int)ofs % (NIDS_PER_BLOCK + 1)))
return false;
}
return true;
}
/*
* For node information
* 这个数据结构建立了起来indoe number 所属的node info
*/
struct node_info {
nid_t nid; /* node id, index from 0 to pyhsical max node number - 1 */
nid_t ino; /* inode number of the node's owner */
block_t blk_addr; /* block address of the node */
unsigned char version; /* version of the node */
unsigned char flag; /* for node information bits */
};
struct nat_entry {
struct list_head list; /* for clean or dirty nat list */
struct node_info ni; /* in-memory node information */
};
由此可见， node id是per inode的， 所以NAT journal中还需要记录其他inode number 机器blkaddr, 这里的blkaddr是一个 物理上的地址。
相关的函数有：
