text: // SPDX-License-Identifier: GPL-2.0
  /*
   * fs/f2fs/segment.h
   *
   * Copyright (c) 2012 Samsung Electronics Co., Ltd.
   *             http://www.samsung.com/
   */
  #include <linux/blkdev.h>
  #include <linux/backing-dev.h>
  
  /* constant macro */
  #define NULL_SEGNO			((unsigned int)(~0))
  #define NULL_SECNO			((unsigned int)(~0))
  
  #define DEF_RECLAIM_PREFREE_SEGMENTS	5	/* 5% over total segments */
  #define DEF_MAX_RECLAIM_PREFREE_SEGMENTS	4096	/* 8GB in maximum */
  
  #define F2FS_MIN_SEGMENTS	9 /* SB + 2 (CP + SIT + NAT) + SSA + MAIN */
  
  /* L: Logical segment # in volume, R: Relative segment # in main area */
  #define GET_L2R_SEGNO(free_i, segno)	((segno) - (free_i)->start_segno)
  #define GET_R2L_SEGNO(free_i, segno)	((segno) + (free_i)->start_segno)
  
  #define IS_DATASEG(t)	((t) <= CURSEG_COLD_DATA)
  #define IS_NODESEG(t)	((t) >= CURSEG_HOT_NODE)
  
  #define IS_HOT(t)	((t) == CURSEG_HOT_NODE || (t) == CURSEG_HOT_DATA)
  #define IS_WARM(t)	((t) == CURSEG_WARM_NODE || (t) == CURSEG_WARM_DATA)
  #define IS_COLD(t)	((t) == CURSEG_COLD_NODE || (t) == CURSEG_COLD_DATA)
  
  #define IS_CURSEG(sbi, seg)						\
  	(((seg) == CURSEG_I(sbi, CURSEG_HOT_DATA)->segno) ||	\
  	 ((seg) == CURSEG_I(sbi, CURSEG_WARM_DATA)->segno) ||	\
  	 ((seg) == CURSEG_I(sbi, CURSEG_COLD_DATA)->segno) ||	\
  	 ((seg) == CURSEG_I(sbi, CURSEG_HOT_NODE)->segno) ||	\
  	 ((seg) == CURSEG_I(sbi, CURSEG_WARM_NODE)->segno) ||	\
  	 ((seg) == CURSEG_I(sbi, CURSEG_COLD_NODE)->segno))
  
  #define IS_CURSEC(sbi, secno)						\
  	(((secno) == CURSEG_I(sbi, CURSEG_HOT_DATA)->segno /		\
  	  (sbi)->segs_per_sec) ||	\
  	 ((secno) == CURSEG_I(sbi, CURSEG_WARM_DATA)->segno /		\
  	  (sbi)->segs_per_sec) ||	\
  	 ((secno) == CURSEG_I(sbi, CURSEG_COLD_DATA)->segno /		\
  	  (sbi)->segs_per_sec) ||	\
  	 ((secno) == CURSEG_I(sbi, CURSEG_HOT_NODE)->segno /		\
  	  (sbi)->segs_per_sec) ||	\
  	 ((secno) == CURSEG_I(sbi, CURSEG_WARM_NODE)->segno /		\
  	  (sbi)->segs_per_sec) ||	\
  	 ((secno) == CURSEG_I(sbi, CURSEG_COLD_NODE)->segno /		\
  	  (sbi)->segs_per_sec))	\
  
  #define MAIN_BLKADDR(sbi)						\
  	(SM_I(sbi) ? SM_I(sbi)->main_blkaddr : 				\
  		le32_to_cpu(F2FS_RAW_SUPER(sbi)->main_blkaddr))
  #define SEG0_BLKADDR(sbi)						\
  	(SM_I(sbi) ? SM_I(sbi)->seg0_blkaddr : 				\
  		le32_to_cpu(F2FS_RAW_SUPER(sbi)->segment0_blkaddr))
  
  #define MAIN_SEGS(sbi)	(SM_I(sbi)->main_segments)
  #define MAIN_SECS(sbi)	((sbi)->total_sections)
  
  #define TOTAL_SEGS(sbi)							\
  	(SM_I(sbi) ? SM_I(sbi)->segment_count : 				\
  		le32_to_cpu(F2FS_RAW_SUPER(sbi)->segment_count))
  #define TOTAL_BLKS(sbi)	(TOTAL_SEGS(sbi) << (sbi)->log_blocks_per_seg)
  
  #define MAX_BLKADDR(sbi)	(SEG0_BLKADDR(sbi) + TOTAL_BLKS(sbi))
  #define SEGMENT_SIZE(sbi)	(1ULL << ((sbi)->log_blocksize +	\
  					(sbi)->log_blocks_per_seg))
  
  #define START_BLOCK(sbi, segno)	(SEG0_BLKADDR(sbi) +			\
  	 (GET_R2L_SEGNO(FREE_I(sbi), segno) << (sbi)->log_blocks_per_seg))
  
  #define NEXT_FREE_BLKADDR(sbi, curseg)					\
  	(START_BLOCK(sbi, (curseg)->segno) + (curseg)->next_blkoff)
  
  #define GET_SEGOFF_FROM_SEG0(sbi, blk_addr)	((blk_addr) - SEG0_BLKADDR(sbi))
  #define GET_SEGNO_FROM_SEG0(sbi, blk_addr)				\
  	(GET_SEGOFF_FROM_SEG0(sbi, blk_addr) >> (sbi)->log_blocks_per_seg)
  #define GET_BLKOFF_FROM_SEG0(sbi, blk_addr)				\
  	(GET_SEGOFF_FROM_SEG0(sbi, blk_addr) & ((sbi)->blocks_per_seg - 1))
  
  #define GET_SEGNO(sbi, blk_addr)					\
  	((!__is_valid_data_blkaddr(blk_addr)) ?			\
  	NULL_SEGNO : GET_L2R_SEGNO(FREE_I(sbi),			\
  		GET_SEGNO_FROM_SEG0(sbi, blk_addr)))
  #define BLKS_PER_SEC(sbi)					\
  	((sbi)->segs_per_sec * (sbi)->blocks_per_seg)
  #define GET_SEC_FROM_SEG(sbi, segno)				\
  	((segno) / (sbi)->segs_per_sec)
  #define GET_SEG_FROM_SEC(sbi, secno)				\
  	((secno) * (sbi)->segs_per_sec)
  #define GET_ZONE_FROM_SEC(sbi, secno)				\
  	((secno) / (sbi)->secs_per_zone)
  #define GET_ZONE_FROM_SEG(sbi, segno)				\
  	GET_ZONE_FROM_SEC(sbi, GET_SEC_FROM_SEG(sbi, segno))
  
  #define GET_SUM_BLOCK(sbi, segno)				\
  	((sbi)->sm_info->ssa_blkaddr + (segno))
  
  #define GET_SUM_TYPE(footer) ((footer)->entry_type)
  #define SET_SUM_TYPE(footer, type) ((footer)->entry_type = (type))
  
  #define SIT_ENTRY_OFFSET(sit_i, segno)					\
  	((segno) % (sit_i)->sents_per_block)
  #define SIT_BLOCK_OFFSET(segno)					\
  	((segno) / SIT_ENTRY_PER_BLOCK)
  #define	START_SEGNO(segno)		\
  	(SIT_BLOCK_OFFSET(segno) * SIT_ENTRY_PER_BLOCK)
  #define SIT_BLK_CNT(sbi)			\
  	DIV_ROUND_UP(MAIN_SEGS(sbi), SIT_ENTRY_PER_BLOCK)
  #define f2fs_bitmap_size(nr)			\
  	(BITS_TO_LONGS(nr) * sizeof(unsigned long))
  
  #define SECTOR_FROM_BLOCK(blk_addr)					\
  	(((sector_t)blk_addr) << F2FS_LOG_SECTORS_PER_BLOCK)
  #define SECTOR_TO_BLOCK(sectors)					\
  	((sectors) >> F2FS_LOG_SECTORS_PER_BLOCK)
  
  /*
   * indicate a block allocation direction: RIGHT and LEFT.
   * RIGHT means allocating new sections towards the end of volume.
   * LEFT means the opposite direction.
   */
  enum {
  	ALLOC_RIGHT = 0,
  	ALLOC_LEFT
  };
  
  /*
   * In the victim_sel_policy->alloc_mode, there are two block allocation modes.
   * LFS writes data sequentially with cleaning operations.
   * SSR (Slack Space Recycle) reuses obsolete space without cleaning operations.
   */
  enum {
  	LFS = 0,
  	SSR
  };
  
  /*
   * In the victim_sel_policy->gc_mode, there are two gc, aka cleaning, modes.
   * GC_CB is based on cost-benefit algorithm.
   * GC_GREEDY is based on greedy algorithm.
   */
  enum {
  	GC_CB = 0,
  	GC_GREEDY,
  	ALLOC_NEXT,
  	FLUSH_DEVICE,
  	MAX_GC_POLICY,
  };
  
  /*
   * BG_GC means the background cleaning job.
   * FG_GC means the on-demand cleaning job.
   * FORCE_FG_GC means on-demand cleaning job in background.
   */
  enum {
  	BG_GC = 0,
  	FG_GC,
  	FORCE_FG_GC,
  };
  
  /* for a function parameter to select a victim segment */
  struct victim_sel_policy {
  	int alloc_mode;			/* LFS or SSR */
  	int gc_mode;			/* GC_CB or GC_GREEDY */
  	unsigned long *dirty_segmap;	/* dirty segment bitmap */
  	unsigned int max_search;	/* maximum # of segments to search */
  	unsigned int offset;		/* last scanned bitmap offset */
  	unsigned int ofs_unit;		/* bitmap search unit */
  	unsigned int min_cost;		/* minimum cost */
  	unsigned int min_segno;		/* segment # having min. cost */
  };
  
  struct seg_entry {
  	unsigned int type:6;		/* segment type like CURSEG_XXX_TYPE */
  	unsigned int valid_blocks:10;	/* # of valid blocks */
  	unsigned int ckpt_valid_blocks:10;	/* # of valid blocks last cp */
  	unsigned int padding:6;		/* padding */
  	unsigned char *cur_valid_map;	/* validity bitmap of blocks */
  #ifdef CONFIG_F2FS_CHECK_FS
  	unsigned char *cur_valid_map_mir;	/* mirror of current valid bitmap */
  #endif
  	/*
  	 * # of valid blocks and the validity bitmap stored in the the last
  	 * checkpoint pack. This information is used by the SSR mode.
  	 */
  	unsigned char *ckpt_valid_map;	/* validity bitmap of blocks last cp */
  	unsigned char *discard_map;
  	unsigned long long mtime;	/* modification time of the segment */
  };
  
  struct sec_entry {
  	unsigned int valid_blocks;	/* # of valid blocks in a section */
  };
  
  struct segment_allocation {
  	void (*allocate_segment)(struct f2fs_sb_info *, int, bool);
  };
  
  /*
   * this value is set in page as a private data which indicate that
   * the page is atomically written, and it is in inmem_pages list.
   */
  #define ATOMIC_WRITTEN_PAGE		((unsigned long)-1)
  #define DUMMY_WRITTEN_PAGE		((unsigned long)-2)
  
  #define IS_ATOMIC_WRITTEN_PAGE(page)			\
  		(page_private(page) == (unsigned long)ATOMIC_WRITTEN_PAGE)
  #define IS_DUMMY_WRITTEN_PAGE(page)			\
  		(page_private(page) == (unsigned long)DUMMY_WRITTEN_PAGE)
  
  #define MAX_SKIP_GC_COUNT			16
  
  struct inmem_pages {
  	struct list_head list;
  	struct page *page;
  	block_t old_addr;		/* for revoking when fail to commit */
  };
  
  struct sit_info {
  	const struct segment_allocation *s_ops;
  
  	block_t sit_base_addr;		/* start block address of SIT area */
  	block_t sit_blocks;		/* # of blocks used by SIT area */
  	block_t written_valid_blocks;	/* # of valid blocks in main area */
  	char *sit_bitmap;		/* SIT bitmap pointer */
  #ifdef CONFIG_F2FS_CHECK_FS
  	char *sit_bitmap_mir;		/* SIT bitmap mirror */
  #endif
  	unsigned int bitmap_size;	/* SIT bitmap size */
  
  	unsigned long *tmp_map;			/* bitmap for temporal use */
  	unsigned long *dirty_sentries_bitmap;	/* bitmap for dirty sentries */
  	unsigned int dirty_sentries;		/* # of dirty sentries */
  	unsigned int sents_per_block;		/* # of SIT entries per block */
  	struct rw_semaphore sentry_lock;	/* to protect SIT cache */
  	struct seg_entry *sentries;		/* SIT segment-level cache */
  	struct sec_entry *sec_entries;		/* SIT section-level cache */
  
  	/* for cost-benefit algorithm in cleaning procedure */
  	unsigned long long elapsed_time;	/* elapsed time after mount */
  	unsigned long long mounted_time;	/* mount time */
  	unsigned long long min_mtime;		/* min. modification time */
  	unsigned long long max_mtime;		/* max. modification time */
  
  	unsigned int last_victim[MAX_GC_POLICY]; /* last victim segment # */
  };
  
  struct free_segmap_info {
  	unsigned int start_segno;	/* start segment number logically */
  	unsigned int free_segments;	/* # of free segments */
  	unsigned int free_sections;	/* # of free sections */
  	spinlock_t segmap_lock;		/* free segmap lock */
  	unsigned long *free_segmap;	/* free segment bitmap */
  	unsigned long *free_secmap;	/* free section bitmap */
  };
  
  /* Notice: The order of dirty type is same with CURSEG_XXX in f2fs.h */
  enum dirty_type {
  	DIRTY_HOT_DATA,		/* dirty segments assigned as hot data logs */
  	DIRTY_WARM_DATA,	/* dirty segments assigned as warm data logs */
  	DIRTY_COLD_DATA,	/* dirty segments assigned as cold data logs */
  	DIRTY_HOT_NODE,		/* dirty segments assigned as hot node logs */
  	DIRTY_WARM_NODE,	/* dirty segments assigned as warm node logs */
  	DIRTY_COLD_NODE,	/* dirty segments assigned as cold node logs */
  	DIRTY,			/* to count # of dirty segments */
  	PRE,			/* to count # of entirely obsolete segments */
  	NR_DIRTY_TYPE
  };
  
  struct dirty_seglist_info {
  	const struct victim_selection *v_ops;	/* victim selction operation */
  	unsigned long *dirty_segmap[NR_DIRTY_TYPE];
  	struct mutex seglist_lock;		/* lock for segment bitmaps */
  	int nr_dirty[NR_DIRTY_TYPE];		/* # of dirty segments */
  	unsigned long *victim_secmap;		/* background GC victims */
  };
  
  /* victim selection function for cleaning and SSR */
  struct victim_selection {
  	int (*get_victim)(struct f2fs_sb_info *, unsigned int *,
  							int, int, char);
  };
  
  /* for active log information */
  struct curseg_info {
  	struct mutex curseg_mutex;		/* lock for consistency */
  	struct f2fs_summary_block *sum_blk;	/* cached summary block */
  	struct rw_semaphore journal_rwsem;	/* protect journal area */
  	struct f2fs_journal *journal;		/* cached journal info */
  	unsigned char alloc_type;		/* current allocation type */
  	unsigned int segno;			/* current segment number */
  	unsigned short next_blkoff;		/* next block offset to write */
  	unsigned int zone;			/* current zone number */
  	unsigned int next_segno;		/* preallocated segment */
  };
  
  struct sit_entry_set {
  	struct list_head set_list;	/* link with all sit sets */
  	unsigned int start_segno;	/* start segno of sits in set */
  	unsigned int entry_cnt;		/* the # of sit entries in set */
  };
  
  /*
   * inline functions
   */
  static inline struct curseg_info *CURSEG_I(struct f2fs_sb_info *sbi, int type)
  {
  	return (struct curseg_info *)(SM_I(sbi)->curseg_array + type);
  }
  
  static inline struct seg_entry *get_seg_entry(struct f2fs_sb_info *sbi,
  						unsigned int segno)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	return &sit_i->sentries[segno];
  }
  
  static inline struct sec_entry *get_sec_entry(struct f2fs_sb_info *sbi,
  						unsigned int segno)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	return &sit_i->sec_entries[GET_SEC_FROM_SEG(sbi, segno)];
  }
  
  static inline unsigned int get_valid_blocks(struct f2fs_sb_info *sbi,
  				unsigned int segno, bool use_section)
  {
  	/*
  	 * In order to get # of valid blocks in a section instantly from many
  	 * segments, f2fs manages two counting structures separately.
  	 */
  	if (use_section && __is_large_section(sbi))
  		return get_sec_entry(sbi, segno)->valid_blocks;
  	else
  		return get_seg_entry(sbi, segno)->valid_blocks;
  }
  
  static inline unsigned int get_ckpt_valid_blocks(struct f2fs_sb_info *sbi,
  				unsigned int segno)
  {
  	return get_seg_entry(sbi, segno)->ckpt_valid_blocks;
  }
  
  static inline void seg_info_from_raw_sit(struct seg_entry *se,
  					struct f2fs_sit_entry *rs)
  {
  	se->valid_blocks = GET_SIT_VBLOCKS(rs);
  	se->ckpt_valid_blocks = GET_SIT_VBLOCKS(rs);
  	memcpy(se->cur_valid_map, rs->valid_map, SIT_VBLOCK_MAP_SIZE);
  	memcpy(se->ckpt_valid_map, rs->valid_map, SIT_VBLOCK_MAP_SIZE);
  #ifdef CONFIG_F2FS_CHECK_FS
  	memcpy(se->cur_valid_map_mir, rs->valid_map, SIT_VBLOCK_MAP_SIZE);
  #endif
  	se->type = GET_SIT_TYPE(rs);
  	se->mtime = le64_to_cpu(rs->mtime);
  }
  
  static inline void __seg_info_to_raw_sit(struct seg_entry *se,
  					struct f2fs_sit_entry *rs)
  {
  	unsigned short raw_vblocks = (se->type << SIT_VBLOCKS_SHIFT) |
  					se->valid_blocks;
  	rs->vblocks = cpu_to_le16(raw_vblocks);
  	memcpy(rs->valid_map, se->cur_valid_map, SIT_VBLOCK_MAP_SIZE);
  	rs->mtime = cpu_to_le64(se->mtime);
  }
  
  static inline void seg_info_to_sit_page(struct f2fs_sb_info *sbi,
  				struct page *page, unsigned int start)
  {
  	struct f2fs_sit_block *raw_sit;
  	struct seg_entry *se;
  	struct f2fs_sit_entry *rs;
  	unsigned int end = min(start + SIT_ENTRY_PER_BLOCK,
  					(unsigned long)MAIN_SEGS(sbi));
  	int i;
  
  	raw_sit = (struct f2fs_sit_block *)page_address(page);
  	memset(raw_sit, 0, PAGE_SIZE);
  	for (i = 0; i < end - start; i++) {
  		rs = &raw_sit->entries[i];
  		se = get_seg_entry(sbi, start + i);
  		__seg_info_to_raw_sit(se, rs);
  	}
  }
  
  static inline void seg_info_to_raw_sit(struct seg_entry *se,
  					struct f2fs_sit_entry *rs)
  {
  	__seg_info_to_raw_sit(se, rs);
  
  	memcpy(se->ckpt_valid_map, rs->valid_map, SIT_VBLOCK_MAP_SIZE);
  	se->ckpt_valid_blocks = se->valid_blocks;
  }
  
  static inline unsigned int find_next_inuse(struct free_segmap_info *free_i,
  		unsigned int max, unsigned int segno)
  {
  	unsigned int ret;
  	spin_lock(&free_i->segmap_lock);
  	ret = find_next_bit(free_i->free_segmap, max, segno);
  	spin_unlock(&free_i->segmap_lock);
  	return ret;
  }
  
  static inline void __set_free(struct f2fs_sb_info *sbi, unsigned int segno)
  {
  	struct free_segmap_info *free_i = FREE_I(sbi);
  	unsigned int secno = GET_SEC_FROM_SEG(sbi, segno);
  	unsigned int start_segno = GET_SEG_FROM_SEC(sbi, secno);
  	unsigned int next;
  
  	spin_lock(&free_i->segmap_lock);
  	clear_bit(segno, free_i->free_segmap);
  	free_i->free_segments++;
  
  	next = find_next_bit(free_i->free_segmap,
  			start_segno + sbi->segs_per_sec, start_segno);
  	if (next >= start_segno + sbi->segs_per_sec) {
  		clear_bit(secno, free_i->free_secmap);
  		free_i->free_sections++;
  	}
  	spin_unlock(&free_i->segmap_lock);
  }
  
  static inline void __set_inuse(struct f2fs_sb_info *sbi,
  		unsigned int segno)
  {
  	struct free_segmap_info *free_i = FREE_I(sbi);
  	unsigned int secno = GET_SEC_FROM_SEG(sbi, segno);
  
  	set_bit(segno, free_i->free_segmap);
  	free_i->free_segments--;
  	if (!test_and_set_bit(secno, free_i->free_secmap))
  		free_i->free_sections--;
  }
  
  static inline void __set_test_and_free(struct f2fs_sb_info *sbi,
  		unsigned int segno)
  {
  	struct free_segmap_info *free_i = FREE_I(sbi);
  	unsigned int secno = GET_SEC_FROM_SEG(sbi, segno);
  	unsigned int start_segno = GET_SEG_FROM_SEC(sbi, secno);
  	unsigned int next;
  
  	spin_lock(&free_i->segmap_lock);
  	if (test_and_clear_bit(segno, free_i->free_segmap)) {
  		free_i->free_segments++;
  
  		if (IS_CURSEC(sbi, secno))
  			goto skip_free;
  		next = find_next_bit(free_i->free_segmap,
  				start_segno + sbi->segs_per_sec, start_segno);
  		if (next >= start_segno + sbi->segs_per_sec) {
  			if (test_and_clear_bit(secno, free_i->free_secmap))
  				free_i->free_sections++;
  		}
  	}
  skip_free:
  	spin_unlock(&free_i->segmap_lock);
  }
  
  static inline void __set_test_and_inuse(struct f2fs_sb_info *sbi,
  		unsigned int segno)
  {
  	struct free_segmap_info *free_i = FREE_I(sbi);
  	unsigned int secno = GET_SEC_FROM_SEG(sbi, segno);
  
  	spin_lock(&free_i->segmap_lock);
  	if (!test_and_set_bit(segno, free_i->free_segmap)) {
  		free_i->free_segments--;
  		if (!test_and_set_bit(secno, free_i->free_secmap))
  			free_i->free_sections--;
  	}
  	spin_unlock(&free_i->segmap_lock);
  }
  
  static inline void get_sit_bitmap(struct f2fs_sb_info *sbi,
  		void *dst_addr)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  
  #ifdef CONFIG_F2FS_CHECK_FS
  	if (memcmp(sit_i->sit_bitmap, sit_i->sit_bitmap_mir,
  						sit_i->bitmap_size))
  		f2fs_bug_on(sbi, 1);
  #endif
  	memcpy(dst_addr, sit_i->sit_bitmap, sit_i->bitmap_size);
  }
  
  static inline block_t written_block_count(struct f2fs_sb_info *sbi)
  {
  	return SIT_I(sbi)->written_valid_blocks;
  }
  
  static inline unsigned int free_segments(struct f2fs_sb_info *sbi)
  {
  	return FREE_I(sbi)->free_segments;
  }
  
  static inline int reserved_segments(struct f2fs_sb_info *sbi)
  {
  	return SM_I(sbi)->reserved_segments;
  }
  
  static inline unsigned int free_sections(struct f2fs_sb_info *sbi)
  {
  	return FREE_I(sbi)->free_sections;
  }
  
  static inline unsigned int prefree_segments(struct f2fs_sb_info *sbi)
  {
  	return DIRTY_I(sbi)->nr_dirty[PRE];
  }
  
  static inline unsigned int dirty_segments(struct f2fs_sb_info *sbi)
  {
  	return DIRTY_I(sbi)->nr_dirty[DIRTY_HOT_DATA] +
  		DIRTY_I(sbi)->nr_dirty[DIRTY_WARM_DATA] +
  		DIRTY_I(sbi)->nr_dirty[DIRTY_COLD_DATA] +
  		DIRTY_I(sbi)->nr_dirty[DIRTY_HOT_NODE] +
  		DIRTY_I(sbi)->nr_dirty[DIRTY_WARM_NODE] +
  		DIRTY_I(sbi)->nr_dirty[DIRTY_COLD_NODE];
  }
  
  static inline int overprovision_segments(struct f2fs_sb_info *sbi)
  {
  	return SM_I(sbi)->ovp_segments;
  }
  
  static inline int reserved_sections(struct f2fs_sb_info *sbi)
  {
  	return GET_SEC_FROM_SEG(sbi, (unsigned int)reserved_segments(sbi));
  }
  
  static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi)
  {
  	unsigned int node_blocks = get_pages(sbi, F2FS_DIRTY_NODES) +
  					get_pages(sbi, F2FS_DIRTY_DENTS);
  	unsigned int dent_blocks = get_pages(sbi, F2FS_DIRTY_DENTS);
  	unsigned int segno, left_blocks;
  	int i;
  
  	/* check current node segment */
  	for (i = CURSEG_HOT_NODE; i <= CURSEG_COLD_NODE; i++) {
  		segno = CURSEG_I(sbi, i)->segno;
  		left_blocks = sbi->blocks_per_seg -
  			get_seg_entry(sbi, segno)->ckpt_valid_blocks;
  
  		if (node_blocks > left_blocks)
  			return false;
  	}
  
  	/* check current data segment */
  	segno = CURSEG_I(sbi, CURSEG_HOT_DATA)->segno;
  	left_blocks = sbi->blocks_per_seg -
  			get_seg_entry(sbi, segno)->ckpt_valid_blocks;
  	if (dent_blocks > left_blocks)
  		return false;
  	return true;
  }
  
  static inline bool has_not_enough_free_secs(struct f2fs_sb_info *sbi,
  					int freed, int needed)
  {
  	int node_secs = get_blocktype_secs(sbi, F2FS_DIRTY_NODES);
  	int dent_secs = get_blocktype_secs(sbi, F2FS_DIRTY_DENTS);
  	int imeta_secs = get_blocktype_secs(sbi, F2FS_DIRTY_IMETA);
  
  	if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
  		return false;
  
  	if (free_sections(sbi) + freed == reserved_sections(sbi) + needed &&
  			has_curseg_enough_space(sbi))
  		return false;
  	return (free_sections(sbi) + freed) <=
  		(node_secs + 2 * dent_secs + imeta_secs +
  		reserved_sections(sbi) + needed);
  }
  
  static inline int f2fs_is_checkpoint_ready(struct f2fs_sb_info *sbi)
  {
  	if (likely(!is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
  		return 0;
  	if (likely(!has_not_enough_free_secs(sbi, 0, 0)))
  		return 0;
  	return -ENOSPC;
  }
  
  static inline bool excess_prefree_segs(struct f2fs_sb_info *sbi)
  {
  	return prefree_segments(sbi) > SM_I(sbi)->rec_prefree_segments;
  }
  
  static inline int utilization(struct f2fs_sb_info *sbi)
  {
  	return div_u64((u64)valid_user_blocks(sbi) * 100,
  					sbi->user_block_count);
  }
  
  /*
   * Sometimes f2fs may be better to drop out-of-place update policy.
   * And, users can control the policy through sysfs entries.
   * There are five policies with triggering conditions as follows.
   * F2FS_IPU_FORCE - all the time,
   * F2FS_IPU_SSR - if SSR mode is activated,
   * F2FS_IPU_UTIL - if FS utilization is over threashold,
   * F2FS_IPU_SSR_UTIL - if SSR mode is activated and FS utilization is over
   *                     threashold,
   * F2FS_IPU_FSYNC - activated in fsync path only for high performance flash
   *                     storages. IPU will be triggered only if the # of dirty
   *                     pages over min_fsync_blocks.
   * F2FS_IPUT_DISABLE - disable IPU. (=default option)
   */
  #define DEF_MIN_IPU_UTIL	70
  #define DEF_MIN_FSYNC_BLOCKS	8
  #define DEF_MIN_HOT_BLOCKS	16
  
  #define SMALL_VOLUME_SEGMENTS	(16 * 512)	/* 16GB */
  
  enum {
  	F2FS_IPU_FORCE,
  	F2FS_IPU_SSR,
  	F2FS_IPU_UTIL,
  	F2FS_IPU_SSR_UTIL,
  	F2FS_IPU_FSYNC,
  	F2FS_IPU_ASYNC,
  };
  
  static inline unsigned int curseg_segno(struct f2fs_sb_info *sbi,
  		int type)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	return curseg->segno;
  }
  
  static inline unsigned char curseg_alloc_type(struct f2fs_sb_info *sbi,
  		int type)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	return curseg->alloc_type;
  }
  
  static inline unsigned short curseg_blkoff(struct f2fs_sb_info *sbi, int type)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	return curseg->next_blkoff;
  }
  
  static inline void check_seg_range(struct f2fs_sb_info *sbi, unsigned int segno)
  {
  	f2fs_bug_on(sbi, segno > TOTAL_SEGS(sbi) - 1);
  }
  
  static inline void verify_fio_blkaddr(struct f2fs_io_info *fio)
  {
  	struct f2fs_sb_info *sbi = fio->sbi;
  
  	if (__is_valid_data_blkaddr(fio->old_blkaddr))
  		verify_blkaddr(sbi, fio->old_blkaddr, __is_meta_io(fio) ?
  					META_GENERIC : DATA_GENERIC);
  	verify_blkaddr(sbi, fio->new_blkaddr, __is_meta_io(fio) ?
  					META_GENERIC : DATA_GENERIC_ENHANCE);
  }
  
  /*
   * Summary block is always treated as an invalid block
   */
  static inline int check_block_count(struct f2fs_sb_info *sbi,
  		int segno, struct f2fs_sit_entry *raw_sit)
  {
  	bool is_valid  = test_bit_le(0, raw_sit->valid_map) ? true : false;
  	int valid_blocks = 0;
  	int cur_pos = 0, next_pos;
  
  	/* check bitmap with valid block count */
  	do {
  		if (is_valid) {
  			next_pos = find_next_zero_bit_le(&raw_sit->valid_map,
  					sbi->blocks_per_seg,
  					cur_pos);
  			valid_blocks += next_pos - cur_pos;
  		} else
  			next_pos = find_next_bit_le(&raw_sit->valid_map,
  					sbi->blocks_per_seg,
  					cur_pos);
  		cur_pos = next_pos;
  		is_valid = !is_valid;
  	} while (cur_pos < sbi->blocks_per_seg);
  
  	if (unlikely(GET_SIT_VBLOCKS(raw_sit) != valid_blocks)) {
  		f2fs_err(sbi, "Mismatch valid blocks %d vs. %d",
  			 GET_SIT_VBLOCKS(raw_sit), valid_blocks);
  		set_sbi_flag(sbi, SBI_NEED_FSCK);
  		return -EFSCORRUPTED;
  	}
  
  	/* check segment usage, and check boundary of a given segment number */
  	if (unlikely(GET_SIT_VBLOCKS(raw_sit) > sbi->blocks_per_seg
  					|| segno > TOTAL_SEGS(sbi) - 1)) {
  		f2fs_err(sbi, "Wrong valid blocks %d or segno %u",
  			 GET_SIT_VBLOCKS(raw_sit), segno);
  		set_sbi_flag(sbi, SBI_NEED_FSCK);
  		return -EFSCORRUPTED;
  	}
  	return 0;
  }
  
  static inline pgoff_t current_sit_addr(struct f2fs_sb_info *sbi,
  						unsigned int start)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	unsigned int offset = SIT_BLOCK_OFFSET(start);
  	block_t blk_addr = sit_i->sit_base_addr + offset;
  
  	check_seg_range(sbi, start);
  
  #ifdef CONFIG_F2FS_CHECK_FS
  	if (f2fs_test_bit(offset, sit_i->sit_bitmap) !=
  			f2fs_test_bit(offset, sit_i->sit_bitmap_mir))
  		f2fs_bug_on(sbi, 1);
  #endif
  
  	/* calculate sit block address */
  	if (f2fs_test_bit(offset, sit_i->sit_bitmap))
  		blk_addr += sit_i->sit_blocks;
  
  	return blk_addr;
  }
  
  static inline pgoff_t next_sit_addr(struct f2fs_sb_info *sbi,
  						pgoff_t block_addr)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	block_addr -= sit_i->sit_base_addr;
  	if (block_addr < sit_i->sit_blocks)
  		block_addr += sit_i->sit_blocks;
  	else
  		block_addr -= sit_i->sit_blocks;
  
  	return block_addr + sit_i->sit_base_addr;
  }
  
  static inline void set_to_next_sit(struct sit_info *sit_i, unsigned int start)
  {
  	unsigned int block_off = SIT_BLOCK_OFFSET(start);
  
  	f2fs_change_bit(block_off, sit_i->sit_bitmap);
  #ifdef CONFIG_F2FS_CHECK_FS
  	f2fs_change_bit(block_off, sit_i->sit_bitmap_mir);
  #endif
  }
  
  static inline unsigned long long get_mtime(struct f2fs_sb_info *sbi,
  						bool base_time)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	time64_t diff, now = ktime_get_real_seconds();
  
  	if (now >= sit_i->mounted_time)
  		return sit_i->elapsed_time + now - sit_i->mounted_time;
  
  	/* system time is set to the past */
  	if (!base_time) {
  		diff = sit_i->mounted_time - now;
  		if (sit_i->elapsed_time >= diff)
  			return sit_i->elapsed_time - diff;
  		return 0;
  	}
  	return sit_i->elapsed_time;
  }
  
  static inline void set_summary(struct f2fs_summary *sum, nid_t nid,
  			unsigned int ofs_in_node, unsigned char version)
  {
  	sum->nid = cpu_to_le32(nid);
  	sum->ofs_in_node = cpu_to_le16(ofs_in_node);
  	sum->version = version;
  }
  
  static inline block_t start_sum_block(struct f2fs_sb_info *sbi)
  {
  	return __start_cp_addr(sbi) +
  		le32_to_cpu(F2FS_CKPT(sbi)->cp_pack_start_sum);
  }
  
  static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
  {
  	return __start_cp_addr(sbi) +
  		le32_to_cpu(F2FS_CKPT(sbi)->cp_pack_total_block_count)
  				- (base + 1) + type;
  }
  
  static inline bool sec_usage_check(struct f2fs_sb_info *sbi, unsigned int secno)
  {
  	if (IS_CURSEC(sbi, secno) || (sbi->cur_victim_sec == secno))
  		return true;
  	return false;
  }
  
  /*
   * It is very important to gather dirty pages and write at once, so that we can
   * submit a big bio without interfering other data writes.
   * By default, 512 pages for directory data,
   * 512 pages (2MB) * 8 for nodes, and
   * 256 pages * 8 for meta are set.
   */
  static inline int nr_pages_to_skip(struct f2fs_sb_info *sbi, int type)
  {
  	if (sbi->sb->s_bdi->wb.dirty_exceeded)
  		return 0;
  
  	if (type == DATA)
  		return sbi->blocks_per_seg;
  	else if (type == NODE)
  		return 8 * sbi->blocks_per_seg;
  	else if (type == META)
  		return 8 * BIO_MAX_PAGES;
  	else
  		return 0;
  }
  
  /*
   * When writing pages, it'd better align nr_to_write for segment size.
   */
  static inline long nr_pages_to_write(struct f2fs_sb_info *sbi, int type,
  					struct writeback_control *wbc)
  {
  	long nr_to_write, desired;
  
  	if (wbc->sync_mode != WB_SYNC_NONE)
  		return 0;
  
  	nr_to_write = wbc->nr_to_write;
  	desired = BIO_MAX_PAGES;
  	if (type == NODE)
  		desired <<= 1;
  
  	wbc->nr_to_write = desired;
  	return desired - nr_to_write;
  }
  
  static inline void wake_up_discard_thread(struct f2fs_sb_info *sbi, bool force)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	bool wakeup = false;
  	int i;
  
  	if (force)
  		goto wake_up;
  
  	mutex_lock(&dcc->cmd_lock);
  	for (i = MAX_PLIST_NUM - 1; i >= 0; i--) {
  		if (i + 1 < dcc->discard_granularity)
  			break;
  		if (!list_empty(&dcc->pend_list[i])) {
  			wakeup = true;
  			break;
  		}
  	}
  	mutex_unlock(&dcc->cmd_lock);
  	if (!wakeup || !is_idle(sbi, DISCARD_TIME))
  		return;
  wake_up:
  	dcc->discard_wake = 1;
  	wake_up_interruptible_all(&dcc->discard_wait_queue);
  }
  