text: // SPDX-License-Identifier: GPL-2.0
  /*
   * fs/f2fs/segment.c
   *
   * Copyright (c) 2012 Samsung Electronics Co., Ltd.
   *             http://www.samsung.com/
   */
  #include <linux/fs.h>
  #include <linux/f2fs_fs.h>
  #include <linux/bio.h>
  #include <linux/blkdev.h>
  #include <linux/prefetch.h>
  #include <linux/kthread.h>
  #include <linux/swap.h>
  #include <linux/timer.h>
  #include <linux/freezer.h>
  #include <linux/sched/signal.h>
  
  #include "f2fs.h"
  #include "segment.h"
  #include "node.h"
  #include "gc.h"
  #include "trace.h"
  #include <trace/events/f2fs.h>
  
  #define __reverse_ffz(x) __reverse_ffs(~(x))
  
  static struct kmem_cache *discard_entry_slab;
  static struct kmem_cache *discard_cmd_slab;
  static struct kmem_cache *sit_entry_set_slab;
  static struct kmem_cache *inmem_entry_slab;
  
  static unsigned long __reverse_ulong(unsigned char *str)
  {
  	unsigned long tmp = 0;
  	int shift = 24, idx = 0;
  
  #if BITS_PER_LONG == 64
  	shift = 56;
  #endif
  	while (shift >= 0) {
  		tmp |= (unsigned long)str[idx++] << shift;
  		shift -= BITS_PER_BYTE;
  	}
  	return tmp;
  }
  
  /*
   * __reverse_ffs is copied from include/asm-generic/bitops/__ffs.h since
   * MSB and LSB are reversed in a byte by f2fs_set_bit.
   */
  static inline unsigned long __reverse_ffs(unsigned long word)
  {
  	int num = 0;
  
  #if BITS_PER_LONG == 64
  	if ((word & 0xffffffff00000000UL) == 0)
  		num += 32;
  	else
  		word >>= 32;
  #endif
  	if ((word & 0xffff0000) == 0)
  		num += 16;
  	else
  		word >>= 16;
  
  	if ((word & 0xff00) == 0)
  		num += 8;
  	else
  		word >>= 8;
  
  	if ((word & 0xf0) == 0)
  		num += 4;
  	else
  		word >>= 4;
  
  	if ((word & 0xc) == 0)
  		num += 2;
  	else
  		word >>= 2;
  
  	if ((word & 0x2) == 0)
  		num += 1;
  	return num;
  }
  
  /*
   * __find_rev_next(_zero)_bit is copied from lib/find_next_bit.c because
   * f2fs_set_bit makes MSB and LSB reversed in a byte.
   * @size must be integral times of unsigned long.
   * Example:
   *                             MSB <--> LSB
   *   f2fs_set_bit(0, bitmap) => 1000 0000
   *   f2fs_set_bit(7, bitmap) => 0000 0001
   */
  static unsigned long __find_rev_next_bit(const unsigned long *addr,
  			unsigned long size, unsigned long offset)
  {
  	const unsigned long *p = addr + BIT_WORD(offset);
  	unsigned long result = size;
  	unsigned long tmp;
  
  	if (offset >= size)
  		return size;
  
  	size -= (offset & ~(BITS_PER_LONG - 1));
  	offset %= BITS_PER_LONG;
  
  	while (1) {
  		if (*p == 0)
  			goto pass;
  
  		tmp = __reverse_ulong((unsigned char *)p);
  
  		tmp &= ~0UL >> offset;
  		if (size < BITS_PER_LONG)
  			tmp &= (~0UL << (BITS_PER_LONG - size));
  		if (tmp)
  			goto found;
  pass:
  		if (size <= BITS_PER_LONG)
  			break;
  		size -= BITS_PER_LONG;
  		offset = 0;
  		p++;
  	}
  	return result;
  found:
  	return result - size + __reverse_ffs(tmp);
  }
  
  static unsigned long __find_rev_next_zero_bit(const unsigned long *addr,
  			unsigned long size, unsigned long offset)
  {
  	const unsigned long *p = addr + BIT_WORD(offset);
  	unsigned long result = size;
  	unsigned long tmp;
  
  	if (offset >= size)
  		return size;
  
  	size -= (offset & ~(BITS_PER_LONG - 1));
  	offset %= BITS_PER_LONG;
  
  	while (1) {
  		if (*p == ~0UL)
  			goto pass;
  
  		tmp = __reverse_ulong((unsigned char *)p);
  
  		if (offset)
  			tmp |= ~0UL << (BITS_PER_LONG - offset);
  		if (size < BITS_PER_LONG)
  			tmp |= ~0UL >> size;
  		if (tmp != ~0UL)
  			goto found;
  pass:
  		if (size <= BITS_PER_LONG)
  			break;
  		size -= BITS_PER_LONG;
  		offset = 0;
  		p++;
  	}
  	return result;
  found:
  	return result - size + __reverse_ffz(tmp);
  }
  
  bool f2fs_need_SSR(struct f2fs_sb_info *sbi)
  {
  	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 (f2fs_lfs_mode(sbi))
  		return false;
  	if (sbi->gc_mode == GC_URGENT)
  		return true;
  	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
  		return true;
  
  	return free_sections(sbi) <= (node_secs + 2 * dent_secs + imeta_secs +
  			SM_I(sbi)->min_ssr_sections + reserved_sections(sbi));
  }
  
  void f2fs_register_inmem_page(struct inode *inode, struct page *page)
  {
  	struct inmem_pages *new;
  
  	f2fs_trace_pid(page);
  
  	f2fs_set_page_private(page, (unsigned long)ATOMIC_WRITTEN_PAGE);
  
  	new = f2fs_kmem_cache_alloc(inmem_entry_slab, GFP_NOFS);
  
  	/* add atomic page indices to the list */
  	new->page = page;
  	INIT_LIST_HEAD(&new->list);
  
  	/* increase reference count with clean state */
  	get_page(page);
  	mutex_lock(&F2FS_I(inode)->inmem_lock);
  	list_add_tail(&new->list, &F2FS_I(inode)->inmem_pages);
  	inc_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES);
  	mutex_unlock(&F2FS_I(inode)->inmem_lock);
  
  	trace_f2fs_register_inmem_page(page, INMEM);
  }
  
  static int __revoke_inmem_pages(struct inode *inode,
  				struct list_head *head, bool drop, bool recover,
  				bool trylock)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	struct inmem_pages *cur, *tmp;
  	int err = 0;
  
  	list_for_each_entry_safe(cur, tmp, head, list) {
  		struct page *page = cur->page;
  
  		if (drop)
  			trace_f2fs_commit_inmem_page(page, INMEM_DROP);
  
  		if (trylock) {
  			/*
  			 * to avoid deadlock in between page lock and
  			 * inmem_lock.
  			 */
  			if (!trylock_page(page))
  				continue;
  		} else {
  			lock_page(page);
  		}
  
  		f2fs_wait_on_page_writeback(page, DATA, true, true);
  
  		if (recover) {
  			struct dnode_of_data dn;
  			struct node_info ni;
  
  			trace_f2fs_commit_inmem_page(page, INMEM_REVOKE);
  retry:
  			set_new_dnode(&dn, inode, NULL, NULL, 0);
  			err = f2fs_get_dnode_of_data(&dn, page->index,
  								LOOKUP_NODE);
  			if (err) {
  				if (err == -ENOMEM) {
  					congestion_wait(BLK_RW_ASYNC,
  							DEFAULT_IO_TIMEOUT);
  					cond_resched();
  					goto retry;
  				}
  				err = -EAGAIN;
  				goto next;
  			}
  
  			err = f2fs_get_node_info(sbi, dn.nid, &ni);
  			if (err) {
  				f2fs_put_dnode(&dn);
  				return err;
  			}
  
  			if (cur->old_addr == NEW_ADDR) {
  				f2fs_invalidate_blocks(sbi, dn.data_blkaddr);
  				f2fs_update_data_blkaddr(&dn, NEW_ADDR);
  			} else
  				f2fs_replace_block(sbi, &dn, dn.data_blkaddr,
  					cur->old_addr, ni.version, true, true);
  			f2fs_put_dnode(&dn);
  		}
  next:
  		/* we don't need to invalidate this in the sccessful status */
  		if (drop || recover) {
  			ClearPageUptodate(page);
  			clear_cold_data(page);
  		}
  		f2fs_clear_page_private(page);
  		f2fs_put_page(page, 1);
  
  		list_del(&cur->list);
  		kmem_cache_free(inmem_entry_slab, cur);
  		dec_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES);
  	}
  	return err;
  }
  
  void f2fs_drop_inmem_pages_all(struct f2fs_sb_info *sbi, bool gc_failure)
  {
  	struct list_head *head = &sbi->inode_list[ATOMIC_FILE];
  	struct inode *inode;
  	struct f2fs_inode_info *fi;
  	unsigned int count = sbi->atomic_files;
  	unsigned int looped = 0;
  next:
  	spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
  	if (list_empty(head)) {
  		spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
  		return;
  	}
  	fi = list_first_entry(head, struct f2fs_inode_info, inmem_ilist);
  	inode = igrab(&fi->vfs_inode);
  	if (inode)
  		list_move_tail(&fi->inmem_ilist, head);
  	spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
  
  	if (inode) {
  		if (gc_failure) {
  			if (!fi->i_gc_failures[GC_FAILURE_ATOMIC])
  				goto skip;
  		}
  		set_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST);
  		f2fs_drop_inmem_pages(inode);
  skip:
  		iput(inode);
  	}
  	congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
  	cond_resched();
  	if (gc_failure) {
  		if (++looped >= count)
  			return;
  	}
  	goto next;
  }
  
  void f2fs_drop_inmem_pages(struct inode *inode)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	struct f2fs_inode_info *fi = F2FS_I(inode);
  
  	while (!list_empty(&fi->inmem_pages)) {
  		mutex_lock(&fi->inmem_lock);
  		__revoke_inmem_pages(inode, &fi->inmem_pages,
  						true, false, true);
  		mutex_unlock(&fi->inmem_lock);
  	}
  
  	fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0;
  
  	spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
  	if (!list_empty(&fi->inmem_ilist))
  		list_del_init(&fi->inmem_ilist);
  	if (f2fs_is_atomic_file(inode)) {
  		clear_inode_flag(inode, FI_ATOMIC_FILE);
  		sbi->atomic_files--;
  	}
  	spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
  }
  
  void f2fs_drop_inmem_page(struct inode *inode, struct page *page)
  {
  	struct f2fs_inode_info *fi = F2FS_I(inode);
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	struct list_head *head = &fi->inmem_pages;
  	struct inmem_pages *cur = NULL;
  
  	f2fs_bug_on(sbi, !IS_ATOMIC_WRITTEN_PAGE(page));
  
  	mutex_lock(&fi->inmem_lock);
  	list_for_each_entry(cur, head, list) {
  		if (cur->page == page)
  			break;
  	}
  
  	f2fs_bug_on(sbi, list_empty(head) || cur->page != page);
  	list_del(&cur->list);
  	mutex_unlock(&fi->inmem_lock);
  
  	dec_page_count(sbi, F2FS_INMEM_PAGES);
  	kmem_cache_free(inmem_entry_slab, cur);
  
  	ClearPageUptodate(page);
  	f2fs_clear_page_private(page);
  	f2fs_put_page(page, 0);
  
  	trace_f2fs_commit_inmem_page(page, INMEM_INVALIDATE);
  }
  
  static int __f2fs_commit_inmem_pages(struct inode *inode)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	struct f2fs_inode_info *fi = F2FS_I(inode);
  	struct inmem_pages *cur, *tmp;
  	struct f2fs_io_info fio = {
  		.sbi = sbi,
  		.ino = inode->i_ino,
  		.type = DATA,
  		.op = REQ_OP_WRITE,
  		.op_flags = REQ_SYNC | REQ_PRIO,
  		.io_type = FS_DATA_IO,
  	};
  	struct list_head revoke_list;
  	bool submit_bio = false;
  	int err = 0;
  
  	INIT_LIST_HEAD(&revoke_list);
  
  	list_for_each_entry_safe(cur, tmp, &fi->inmem_pages, list) {
  		struct page *page = cur->page;
  
  		lock_page(page);
  		if (page->mapping == inode->i_mapping) {
  			trace_f2fs_commit_inmem_page(page, INMEM);
  
  			f2fs_wait_on_page_writeback(page, DATA, true, true);
  
  			set_page_dirty(page);
  			if (clear_page_dirty_for_io(page)) {
  				inode_dec_dirty_pages(inode);
  				f2fs_remove_dirty_inode(inode);
  			}
  retry:
  			fio.page = page;
  			fio.old_blkaddr = NULL_ADDR;
  			fio.encrypted_page = NULL;
  			fio.need_lock = LOCK_DONE;
  			err = f2fs_do_write_data_page(&fio);
  			if (err) {
  				if (err == -ENOMEM) {
  					congestion_wait(BLK_RW_ASYNC,
  							DEFAULT_IO_TIMEOUT);
  					cond_resched();
  					goto retry;
  				}
  				unlock_page(page);
  				break;
  			}
  			/* record old blkaddr for revoking */
  			cur->old_addr = fio.old_blkaddr;
  			submit_bio = true;
  		}
  		unlock_page(page);
  		list_move_tail(&cur->list, &revoke_list);
  	}
  
  	if (submit_bio)
  		f2fs_submit_merged_write_cond(sbi, inode, NULL, 0, DATA);
  
  	if (err) {
  		/*
  		 * try to revoke all committed pages, but still we could fail
  		 * due to no memory or other reason, if that happened, EAGAIN
  		 * will be returned, which means in such case, transaction is
  		 * already not integrity, caller should use journal to do the
  		 * recovery or rewrite & commit last transaction. For other
  		 * error number, revoking was done by filesystem itself.
  		 */
  		err = __revoke_inmem_pages(inode, &revoke_list,
  						false, true, false);
  
  		/* drop all uncommitted pages */
  		__revoke_inmem_pages(inode, &fi->inmem_pages,
  						true, false, false);
  	} else {
  		__revoke_inmem_pages(inode, &revoke_list,
  						false, false, false);
  	}
  
  	return err;
  }
  
  int f2fs_commit_inmem_pages(struct inode *inode)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	struct f2fs_inode_info *fi = F2FS_I(inode);
  	int err;
  
  	f2fs_balance_fs(sbi, true);
  
  	down_write(&fi->i_gc_rwsem[WRITE]);
  
  	f2fs_lock_op(sbi);
  	set_inode_flag(inode, FI_ATOMIC_COMMIT);
  
  	mutex_lock(&fi->inmem_lock);
  	err = __f2fs_commit_inmem_pages(inode);
  	mutex_unlock(&fi->inmem_lock);
  
  	clear_inode_flag(inode, FI_ATOMIC_COMMIT);
  
  	f2fs_unlock_op(sbi);
  	up_write(&fi->i_gc_rwsem[WRITE]);
  
  	return err;
  }
  
  /*
   * This function balances dirty node and dentry pages.
   * In addition, it controls garbage collection.
   */
  void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
  {
  	if (time_to_inject(sbi, FAULT_CHECKPOINT)) {
  		f2fs_show_injection_info(sbi, FAULT_CHECKPOINT);
  		f2fs_stop_checkpoint(sbi, false);
  	}
  
  	/* balance_fs_bg is able to be pending */
  	if (need && excess_cached_nats(sbi))
  		f2fs_balance_fs_bg(sbi, false);
  
  	if (!f2fs_is_checkpoint_ready(sbi))
  		return;
  
  	/*
  	 * We should do GC or end up with checkpoint, if there are so many dirty
  	 * dir/node pages without enough free segments.
  	 */
  	if (has_not_enough_free_secs(sbi, 0, 0)) {
  		down_write(&sbi->gc_lock);
  		f2fs_gc(sbi, false, false, NULL_SEGNO);
  	}
  }
  
  void f2fs_balance_fs_bg(struct f2fs_sb_info *sbi, bool from_bg)
  {
  	if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
  		return;
  
  	/* try to shrink extent cache when there is no enough memory */
  	if (!f2fs_available_free_memory(sbi, EXTENT_CACHE))
  		f2fs_shrink_extent_tree(sbi, EXTENT_CACHE_SHRINK_NUMBER);
  
  	/* check the # of cached NAT entries */
  	if (!f2fs_available_free_memory(sbi, NAT_ENTRIES))
  		f2fs_try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK);
  
  	if (!f2fs_available_free_memory(sbi, FREE_NIDS))
  		f2fs_try_to_free_nids(sbi, MAX_FREE_NIDS);
  	else
  		f2fs_build_free_nids(sbi, false, false);
  
  	if (!is_idle(sbi, REQ_TIME) &&
  		(!excess_dirty_nats(sbi) && !excess_dirty_nodes(sbi)))
  		return;
  
  	/* checkpoint is the only way to shrink partial cached entries */
  	if (!f2fs_available_free_memory(sbi, NAT_ENTRIES) ||
  			!f2fs_available_free_memory(sbi, INO_ENTRIES) ||
  			excess_prefree_segs(sbi) ||
  			excess_dirty_nats(sbi) ||
  			excess_dirty_nodes(sbi) ||
  			f2fs_time_over(sbi, CP_TIME)) {
  		if (test_opt(sbi, DATA_FLUSH) && from_bg) {
  			struct blk_plug plug;
  
  			mutex_lock(&sbi->flush_lock);
  
  			blk_start_plug(&plug);
  			f2fs_sync_dirty_inodes(sbi, FILE_INODE);
  			blk_finish_plug(&plug);
  
  			mutex_unlock(&sbi->flush_lock);
  		}
  		f2fs_sync_fs(sbi->sb, true);
  		stat_inc_bg_cp_count(sbi->stat_info);
  	}
  }
  
  static int __submit_flush_wait(struct f2fs_sb_info *sbi,
  				struct block_device *bdev)
  {
  	struct bio *bio;
  	int ret;
  
  	bio = f2fs_bio_alloc(sbi, 0, false);
  	if (!bio)
  		return -ENOMEM;
  
  	bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH;
  	bio_set_dev(bio, bdev);
  	ret = submit_bio_wait(bio);
  	bio_put(bio);
  
  	trace_f2fs_issue_flush(bdev, test_opt(sbi, NOBARRIER),
  				test_opt(sbi, FLUSH_MERGE), ret);
  	return ret;
  }
  
  static int submit_flush_wait(struct f2fs_sb_info *sbi, nid_t ino)
  {
  	int ret = 0;
  	int i;
  
  	if (!f2fs_is_multi_device(sbi))
  		return __submit_flush_wait(sbi, sbi->sb->s_bdev);
  
  	for (i = 0; i < sbi->s_ndevs; i++) {
  		if (!f2fs_is_dirty_device(sbi, ino, i, FLUSH_INO))
  			continue;
  		ret = __submit_flush_wait(sbi, FDEV(i).bdev);
  		if (ret)
  			break;
  	}
  	return ret;
  }
  
  static int issue_flush_thread(void *data)
  {
  	struct f2fs_sb_info *sbi = data;
  	struct flush_cmd_control *fcc = SM_I(sbi)->fcc_info;
  	wait_queue_head_t *q = &fcc->flush_wait_queue;
  repeat:
  	if (kthread_should_stop())
  		return 0;
  
  	sb_start_intwrite(sbi->sb);
  
  	if (!llist_empty(&fcc->issue_list)) {
  		struct flush_cmd *cmd, *next;
  		int ret;
  
  		fcc->dispatch_list = llist_del_all(&fcc->issue_list);
  		fcc->dispatch_list = llist_reverse_order(fcc->dispatch_list);
  
  		cmd = llist_entry(fcc->dispatch_list, struct flush_cmd, llnode);
  
  		ret = submit_flush_wait(sbi, cmd->ino);
  		atomic_inc(&fcc->issued_flush);
  
  		llist_for_each_entry_safe(cmd, next,
  					  fcc->dispatch_list, llnode) {
  			cmd->ret = ret;
  			complete(&cmd->wait);
  		}
  		fcc->dispatch_list = NULL;
  	}
  
  	sb_end_intwrite(sbi->sb);
  
  	wait_event_interruptible(*q,
  		kthread_should_stop() || !llist_empty(&fcc->issue_list));
  	goto repeat;
  }
  
  int f2fs_issue_flush(struct f2fs_sb_info *sbi, nid_t ino)
  {
  	struct flush_cmd_control *fcc = SM_I(sbi)->fcc_info;
  	struct flush_cmd cmd;
  	int ret;
  
  	if (test_opt(sbi, NOBARRIER))
  		return 0;
  
  	if (!test_opt(sbi, FLUSH_MERGE)) {
  		atomic_inc(&fcc->queued_flush);
  		ret = submit_flush_wait(sbi, ino);
  		atomic_dec(&fcc->queued_flush);
  		atomic_inc(&fcc->issued_flush);
  		return ret;
  	}
  
  	if (atomic_inc_return(&fcc->queued_flush) == 1 ||
  	    f2fs_is_multi_device(sbi)) {
  		ret = submit_flush_wait(sbi, ino);
  		atomic_dec(&fcc->queued_flush);
  
  		atomic_inc(&fcc->issued_flush);
  		return ret;
  	}
  
  	cmd.ino = ino;
  	init_completion(&cmd.wait);
  
  	llist_add(&cmd.llnode, &fcc->issue_list);
  
  	/* update issue_list before we wake up issue_flush thread */
  	smp_mb();
  
  	if (waitqueue_active(&fcc->flush_wait_queue))
  		wake_up(&fcc->flush_wait_queue);
  
  	if (fcc->f2fs_issue_flush) {
  		wait_for_completion(&cmd.wait);
  		atomic_dec(&fcc->queued_flush);
  	} else {
  		struct llist_node *list;
  
  		list = llist_del_all(&fcc->issue_list);
  		if (!list) {
  			wait_for_completion(&cmd.wait);
  			atomic_dec(&fcc->queued_flush);
  		} else {
  			struct flush_cmd *tmp, *next;
  
  			ret = submit_flush_wait(sbi, ino);
  
  			llist_for_each_entry_safe(tmp, next, list, llnode) {
  				if (tmp == &cmd) {
  					cmd.ret = ret;
  					atomic_dec(&fcc->queued_flush);
  					continue;
  				}
  				tmp->ret = ret;
  				complete(&tmp->wait);
  			}
  		}
  	}
  
  	return cmd.ret;
  }
  
  int f2fs_create_flush_cmd_control(struct f2fs_sb_info *sbi)
  {
  	dev_t dev = sbi->sb->s_bdev->bd_dev;
  	struct flush_cmd_control *fcc;
  	int err = 0;
  
  	if (SM_I(sbi)->fcc_info) {
  		fcc = SM_I(sbi)->fcc_info;
  		if (fcc->f2fs_issue_flush)
  			return err;
  		goto init_thread;
  	}
  
  	fcc = f2fs_kzalloc(sbi, sizeof(struct flush_cmd_control), GFP_KERNEL);
  	if (!fcc)
  		return -ENOMEM;
  	atomic_set(&fcc->issued_flush, 0);
  	atomic_set(&fcc->queued_flush, 0);
  	init_waitqueue_head(&fcc->flush_wait_queue);
  	init_llist_head(&fcc->issue_list);
  	SM_I(sbi)->fcc_info = fcc;
  	if (!test_opt(sbi, FLUSH_MERGE))
  		return err;
  
  init_thread:
  	fcc->f2fs_issue_flush = kthread_run(issue_flush_thread, sbi,
  				"f2fs_flush-%u:%u", MAJOR(dev), MINOR(dev));
  	if (IS_ERR(fcc->f2fs_issue_flush)) {
  		err = PTR_ERR(fcc->f2fs_issue_flush);
  		kvfree(fcc);
  		SM_I(sbi)->fcc_info = NULL;
  		return err;
  	}
  
  	return err;
  }
  
  void f2fs_destroy_flush_cmd_control(struct f2fs_sb_info *sbi, bool free)
  {
  	struct flush_cmd_control *fcc = SM_I(sbi)->fcc_info;
  
  	if (fcc && fcc->f2fs_issue_flush) {
  		struct task_struct *flush_thread = fcc->f2fs_issue_flush;
  
  		fcc->f2fs_issue_flush = NULL;
  		kthread_stop(flush_thread);
  	}
  	if (free) {
  		kvfree(fcc);
  		SM_I(sbi)->fcc_info = NULL;
  	}
  }
  
  int f2fs_flush_device_cache(struct f2fs_sb_info *sbi)
  {
  	int ret = 0, i;
  
  	if (!f2fs_is_multi_device(sbi))
  		return 0;
  
  	for (i = 1; i < sbi->s_ndevs; i++) {
  		if (!f2fs_test_bit(i, (char *)&sbi->dirty_device))
  			continue;
  		ret = __submit_flush_wait(sbi, FDEV(i).bdev);
  		if (ret)
  			break;
  
  		spin_lock(&sbi->dev_lock);
  		f2fs_clear_bit(i, (char *)&sbi->dirty_device);
  		spin_unlock(&sbi->dev_lock);
  	}
  
  	return ret;
  }
  
  static void __locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
  		enum dirty_type dirty_type)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  
  	/* need not be added */
  	if (IS_CURSEG(sbi, segno))
  		return;
  
  	if (!test_and_set_bit(segno, dirty_i->dirty_segmap[dirty_type]))
  		dirty_i->nr_dirty[dirty_type]++;
  
  	if (dirty_type == DIRTY) {
  		struct seg_entry *sentry = get_seg_entry(sbi, segno);
  		enum dirty_type t = sentry->type;
  
  		if (unlikely(t >= DIRTY)) {
  			f2fs_bug_on(sbi, 1);
  			return;
  		}
  		if (!test_and_set_bit(segno, dirty_i->dirty_segmap[t]))
  			dirty_i->nr_dirty[t]++;
  	}
  }
  
  static void __remove_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
  		enum dirty_type dirty_type)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  
  	if (test_and_clear_bit(segno, dirty_i->dirty_segmap[dirty_type]))
  		dirty_i->nr_dirty[dirty_type]--;
  
  	if (dirty_type == DIRTY) {
  		struct seg_entry *sentry = get_seg_entry(sbi, segno);
  		enum dirty_type t = sentry->type;
  
  		if (test_and_clear_bit(segno, dirty_i->dirty_segmap[t]))
  			dirty_i->nr_dirty[t]--;
  
  		if (get_valid_blocks(sbi, segno, true) == 0) {
  			clear_bit(GET_SEC_FROM_SEG(sbi, segno),
  						dirty_i->victim_secmap);
  #ifdef CONFIG_F2FS_CHECK_FS
  			clear_bit(segno, SIT_I(sbi)->invalid_segmap);
  #endif
  		}
  	}
  }
  
  /*
   * Should not occur error such as -ENOMEM.
   * Adding dirty entry into seglist is not critical operation.
   * If a given segment is one of current working segments, it won't be added.
   */
  static void locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  	unsigned short valid_blocks, ckpt_valid_blocks;
  
  	if (segno == NULL_SEGNO || IS_CURSEG(sbi, segno))
  		return;
  
  	mutex_lock(&dirty_i->seglist_lock);
  
  	valid_blocks = get_valid_blocks(sbi, segno, false);
  	ckpt_valid_blocks = get_ckpt_valid_blocks(sbi, segno);
  
  	if (valid_blocks == 0 && (!is_sbi_flag_set(sbi, SBI_CP_DISABLED) ||
  				ckpt_valid_blocks == sbi->blocks_per_seg)) {
  		__locate_dirty_segment(sbi, segno, PRE);
  		__remove_dirty_segment(sbi, segno, DIRTY);
  	} else if (valid_blocks < sbi->blocks_per_seg) {
  		__locate_dirty_segment(sbi, segno, DIRTY);
  	} else {
  		/* Recovery routine with SSR needs this */
  		__remove_dirty_segment(sbi, segno, DIRTY);
  	}
  
  	mutex_unlock(&dirty_i->seglist_lock);
  }
  
  /* This moves currently empty dirty blocks to prefree. Must hold seglist_lock */
  void f2fs_dirty_to_prefree(struct f2fs_sb_info *sbi)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  	unsigned int segno;
  
  	mutex_lock(&dirty_i->seglist_lock);
  	for_each_set_bit(segno, dirty_i->dirty_segmap[DIRTY], MAIN_SEGS(sbi)) {
  		if (get_valid_blocks(sbi, segno, false))
  			continue;
  		if (IS_CURSEG(sbi, segno))
  			continue;
  		__locate_dirty_segment(sbi, segno, PRE);
  		__remove_dirty_segment(sbi, segno, DIRTY);
  	}
  	mutex_unlock(&dirty_i->seglist_lock);
  }
  
  block_t f2fs_get_unusable_blocks(struct f2fs_sb_info *sbi)
  {
  	int ovp_hole_segs =
  		(overprovision_segments(sbi) - reserved_segments(sbi));
  	block_t ovp_holes = ovp_hole_segs << sbi->log_blocks_per_seg;
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  	block_t holes[2] = {0, 0};	/* DATA and NODE */
  	block_t unusable;
  	struct seg_entry *se;
  	unsigned int segno;
  
  	mutex_lock(&dirty_i->seglist_lock);
  	for_each_set_bit(segno, dirty_i->dirty_segmap[DIRTY], MAIN_SEGS(sbi)) {
  		se = get_seg_entry(sbi, segno);
  		if (IS_NODESEG(se->type))
  			holes[NODE] += sbi->blocks_per_seg - se->valid_blocks;
  		else
  			holes[DATA] += sbi->blocks_per_seg - se->valid_blocks;
  	}
  	mutex_unlock(&dirty_i->seglist_lock);
  
  	unusable = holes[DATA] > holes[NODE] ? holes[DATA] : holes[NODE];
  	if (unusable > ovp_holes)
  		return unusable - ovp_holes;
  	return 0;
  }
  
  int f2fs_disable_cp_again(struct f2fs_sb_info *sbi, block_t unusable)
  {
  	int ovp_hole_segs =
  		(overprovision_segments(sbi) - reserved_segments(sbi));
  	if (unusable > F2FS_OPTION(sbi).unusable_cap)
  		return -EAGAIN;
  	if (is_sbi_flag_set(sbi, SBI_CP_DISABLED_QUICK) &&
  		dirty_segments(sbi) > ovp_hole_segs)
  		return -EAGAIN;
  	return 0;
  }
  
  /* This is only used by SBI_CP_DISABLED */
  static unsigned int get_free_segment(struct f2fs_sb_info *sbi)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  	unsigned int segno = 0;
  
  	mutex_lock(&dirty_i->seglist_lock);
  	for_each_set_bit(segno, dirty_i->dirty_segmap[DIRTY], MAIN_SEGS(sbi)) {
  		if (get_valid_blocks(sbi, segno, false))
  			continue;
  		if (get_ckpt_valid_blocks(sbi, segno))
  			continue;
  		mutex_unlock(&dirty_i->seglist_lock);
  		return segno;
  	}
  	mutex_unlock(&dirty_i->seglist_lock);
  	return NULL_SEGNO;
  }
  
  static struct discard_cmd *__create_discard_cmd(struct f2fs_sb_info *sbi,
  		struct block_device *bdev, block_t lstart,
  		block_t start, block_t len)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct list_head *pend_list;
  	struct discard_cmd *dc;
  
  	f2fs_bug_on(sbi, !len);
  
  	pend_list = &dcc->pend_list[plist_idx(len)];
  
  	dc = f2fs_kmem_cache_alloc(discard_cmd_slab, GFP_NOFS);
  	INIT_LIST_HEAD(&dc->list);
  	dc->bdev = bdev;
  	dc->lstart = lstart;
  	dc->start = start;
  	dc->len = len;
  	dc->ref = 0;
  	dc->state = D_PREP;
  	dc->queued = 0;
  	dc->error = 0;
  	init_completion(&dc->wait);
  	list_add_tail(&dc->list, pend_list);
  	spin_lock_init(&dc->lock);
  	dc->bio_ref = 0;
  	atomic_inc(&dcc->discard_cmd_cnt);
  	dcc->undiscard_blks += len;
  
  	return dc;
  }
  
  static struct discard_cmd *__attach_discard_cmd(struct f2fs_sb_info *sbi,
  				struct block_device *bdev, block_t lstart,
  				block_t start, block_t len,
  				struct rb_node *parent, struct rb_node **p,
  				bool leftmost)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct discard_cmd *dc;
  
  	dc = __create_discard_cmd(sbi, bdev, lstart, start, len);
  
  	rb_link_node(&dc->rb_node, parent, p);
  	rb_insert_color_cached(&dc->rb_node, &dcc->root, leftmost);
  
  	return dc;
  }
  
  static void __detach_discard_cmd(struct discard_cmd_control *dcc,
  							struct discard_cmd *dc)
  {
  	if (dc->state == D_DONE)
  		atomic_sub(dc->queued, &dcc->queued_discard);
  
  	list_del(&dc->list);
  	rb_erase_cached(&dc->rb_node, &dcc->root);
  	dcc->undiscard_blks -= dc->len;
  
  	kmem_cache_free(discard_cmd_slab, dc);
  
  	atomic_dec(&dcc->discard_cmd_cnt);
  }
  
  static void __remove_discard_cmd(struct f2fs_sb_info *sbi,
  							struct discard_cmd *dc)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	unsigned long flags;
  
  	trace_f2fs_remove_discard(dc->bdev, dc->start, dc->len);
  
  	spin_lock_irqsave(&dc->lock, flags);
  	if (dc->bio_ref) {
  		spin_unlock_irqrestore(&dc->lock, flags);
  		return;
  	}
  	spin_unlock_irqrestore(&dc->lock, flags);
  
  	f2fs_bug_on(sbi, dc->ref);
  
  	if (dc->error == -EOPNOTSUPP)
  		dc->error = 0;
  
  	if (dc->error)
  		printk_ratelimited(
  			"%sF2FS-fs (%s): Issue discard(%u, %u, %u) failed, ret: %d",
  			KERN_INFO, sbi->sb->s_id,
  			dc->lstart, dc->start, dc->len, dc->error);
  	__detach_discard_cmd(dcc, dc);
  }
  
  static void f2fs_submit_discard_endio(struct bio *bio)
  {
  	struct discard_cmd *dc = (struct discard_cmd *)bio->bi_private;
  	unsigned long flags;
  
  	dc->error = blk_status_to_errno(bio->bi_status);
  
  	spin_lock_irqsave(&dc->lock, flags);
  	dc->bio_ref--;
  	if (!dc->bio_ref && dc->state == D_SUBMIT) {
  		dc->state = D_DONE;
  		complete_all(&dc->wait);
  	}
  	spin_unlock_irqrestore(&dc->lock, flags);
  	bio_put(bio);
  }
  
  static void __check_sit_bitmap(struct f2fs_sb_info *sbi,
  				block_t start, block_t end)
  {
  #ifdef CONFIG_F2FS_CHECK_FS
  	struct seg_entry *sentry;
  	unsigned int segno;
  	block_t blk = start;
  	unsigned long offset, size, max_blocks = sbi->blocks_per_seg;
  	unsigned long *map;
  
  	while (blk < end) {
  		segno = GET_SEGNO(sbi, blk);
  		sentry = get_seg_entry(sbi, segno);
  		offset = GET_BLKOFF_FROM_SEG0(sbi, blk);
  
  		if (end < START_BLOCK(sbi, segno + 1))
  			size = GET_BLKOFF_FROM_SEG0(sbi, end);
  		else
  			size = max_blocks;
  		map = (unsigned long *)(sentry->cur_valid_map);
  		offset = __find_rev_next_bit(map, size, offset);
  		f2fs_bug_on(sbi, offset != size);
  		blk = START_BLOCK(sbi, segno + 1);
  	}
  #endif
  }
  
  static void __init_discard_policy(struct f2fs_sb_info *sbi,
  				struct discard_policy *dpolicy,
  				int discard_type, unsigned int granularity)
  {
  	/* common policy */
  	dpolicy->type = discard_type;
  	dpolicy->sync = true;
  	dpolicy->ordered = false;
  	dpolicy->granularity = granularity;
  
  	dpolicy->max_requests = DEF_MAX_DISCARD_REQUEST;
  	dpolicy->io_aware_gran = MAX_PLIST_NUM;
  	dpolicy->timeout = false;
  
  	if (discard_type == DPOLICY_BG) {
  		dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
  		dpolicy->mid_interval = DEF_MID_DISCARD_ISSUE_TIME;
  		dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
  		dpolicy->io_aware = true;
  		dpolicy->sync = false;
  		dpolicy->ordered = true;
  		if (utilization(sbi) > DEF_DISCARD_URGENT_UTIL) {
  			dpolicy->granularity = 1;
  			dpolicy->max_interval = DEF_MIN_DISCARD_ISSUE_TIME;
  		}
  	} else if (discard_type == DPOLICY_FORCE) {
  		dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
  		dpolicy->mid_interval = DEF_MID_DISCARD_ISSUE_TIME;
  		dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
  		dpolicy->io_aware = false;
  	} else if (discard_type == DPOLICY_FSTRIM) {
  		dpolicy->io_aware = false;
  	} else if (discard_type == DPOLICY_UMOUNT) {
  		dpolicy->max_requests = UINT_MAX;
  		dpolicy->io_aware = false;
  		/* we need to issue all to keep CP_TRIMMED_FLAG */
  		dpolicy->granularity = 1;
  		dpolicy->timeout = true;
  	}
  }
  
  static void __update_discard_tree_range(struct f2fs_sb_info *sbi,
  				struct block_device *bdev, block_t lstart,
  				block_t start, block_t len);
  /* this function is copied from blkdev_issue_discard from block/blk-lib.c */
  static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
  						struct discard_policy *dpolicy,
  						struct discard_cmd *dc,
  						unsigned int *issued)
  {
  	struct block_device *bdev = dc->bdev;
  	struct request_queue *q = bdev_get_queue(bdev);
  	unsigned int max_discard_blocks =
  			SECTOR_TO_BLOCK(q->limits.max_discard_sectors);
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct list_head *wait_list = (dpolicy->type == DPOLICY_FSTRIM) ?
  					&(dcc->fstrim_list) : &(dcc->wait_list);
  	int flag = dpolicy->sync ? REQ_SYNC : 0;
  	block_t lstart, start, len, total_len;
  	int err = 0;
  
  	if (dc->state != D_PREP)
  		return 0;
  
  	if (is_sbi_flag_set(sbi, SBI_NEED_FSCK))
  		return 0;
  
  	trace_f2fs_issue_discard(bdev, dc->start, dc->len);
  
  	lstart = dc->lstart;
  	start = dc->start;
  	len = dc->len;
  	total_len = len;
  
  	dc->len = 0;
  
  	while (total_len && *issued < dpolicy->max_requests && !err) {
  		struct bio *bio = NULL;
  		unsigned long flags;
  		bool last = true;
  
  		if (len > max_discard_blocks) {
  			len = max_discard_blocks;
  			last = false;
  		}
  
  		(*issued)++;
  		if (*issued == dpolicy->max_requests)
  			last = true;
  
  		dc->len += len;
  
  		if (time_to_inject(sbi, FAULT_DISCARD)) {
  			f2fs_show_injection_info(sbi, FAULT_DISCARD);
  			err = -EIO;
  			goto submit;
  		}
  		err = __blkdev_issue_discard(bdev,
  					SECTOR_FROM_BLOCK(start),
  					SECTOR_FROM_BLOCK(len),
  					GFP_NOFS, 0, &bio);
  submit:
  		if (err) {
  			spin_lock_irqsave(&dc->lock, flags);
  			if (dc->state == D_PARTIAL)
  				dc->state = D_SUBMIT;
  			spin_unlock_irqrestore(&dc->lock, flags);
  
  			break;
  		}
  
  		f2fs_bug_on(sbi, !bio);
  
  		/*
  		 * should keep before submission to avoid D_DONE
  		 * right away
  		 */
  		spin_lock_irqsave(&dc->lock, flags);
  		if (last)
  			dc->state = D_SUBMIT;
  		else
  			dc->state = D_PARTIAL;
  		dc->bio_ref++;
  		spin_unlock_irqrestore(&dc->lock, flags);
  
  		atomic_inc(&dcc->queued_discard);
  		dc->queued++;
  		list_move_tail(&dc->list, wait_list);
  
  		/* sanity check on discard range */
  		__check_sit_bitmap(sbi, lstart, lstart + len);
  
  		bio->bi_private = dc;
  		bio->bi_end_io = f2fs_submit_discard_endio;
  		bio->bi_opf |= flag;
  		submit_bio(bio);
  
  		atomic_inc(&dcc->issued_discard);
  
  		f2fs_update_iostat(sbi, FS_DISCARD, 1);
  
  		lstart += len;
  		start += len;
  		total_len -= len;
  		len = total_len;
  	}
  
  	if (!err && len)
  		__update_discard_tree_range(sbi, bdev, lstart, start, len);
  	return err;
  }
  
  static struct discard_cmd *__insert_discard_tree(struct f2fs_sb_info *sbi,
  				struct block_device *bdev, block_t lstart,
  				block_t start, block_t len,
  				struct rb_node **insert_p,
  				struct rb_node *insert_parent)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct rb_node **p;
  	struct rb_node *parent = NULL;
  	struct discard_cmd *dc = NULL;
  	bool leftmost = true;
  
  	if (insert_p && insert_parent) {
  		parent = insert_parent;
  		p = insert_p;
  		goto do_insert;
  	}
  
  	p = f2fs_lookup_rb_tree_for_insert(sbi, &dcc->root, &parent,
  							lstart, &leftmost);
  do_insert:
  	dc = __attach_discard_cmd(sbi, bdev, lstart, start, len, parent,
  								p, leftmost);
  	if (!dc)
  		return NULL;
  
  	return dc;
  }
  
  static void __relocate_discard_cmd(struct discard_cmd_control *dcc,
  						struct discard_cmd *dc)
  {
  	list_move_tail(&dc->list, &dcc->pend_list[plist_idx(dc->len)]);
  }
  
  static void __punch_discard_cmd(struct f2fs_sb_info *sbi,
  				struct discard_cmd *dc, block_t blkaddr)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct discard_info di = dc->di;
  	bool modified = false;
  
  	if (dc->state == D_DONE || dc->len == 1) {
  		__remove_discard_cmd(sbi, dc);
  		return;
  	}
  
  	dcc->undiscard_blks -= di.len;
  
  	if (blkaddr > di.lstart) {
  		dc->len = blkaddr - dc->lstart;
  		dcc->undiscard_blks += dc->len;
  		__relocate_discard_cmd(dcc, dc);
  		modified = true;
  	}
  
  	if (blkaddr < di.lstart + di.len - 1) {
  		if (modified) {
  			__insert_discard_tree(sbi, dc->bdev, blkaddr + 1,
  					di.start + blkaddr + 1 - di.lstart,
  					di.lstart + di.len - 1 - blkaddr,
  					NULL, NULL);
  		} else {
  			dc->lstart++;
  			dc->len--;
  			dc->start++;
  			dcc->undiscard_blks += dc->len;
  			__relocate_discard_cmd(dcc, dc);
  		}
  	}
  }
  
  static void __update_discard_tree_range(struct f2fs_sb_info *sbi,
  				struct block_device *bdev, block_t lstart,
  				block_t start, block_t len)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct discard_cmd *prev_dc = NULL, *next_dc = NULL;
  	struct discard_cmd *dc;
  	struct discard_info di = {0};
  	struct rb_node **insert_p = NULL, *insert_parent = NULL;
  	struct request_queue *q = bdev_get_queue(bdev);
  	unsigned int max_discard_blocks =
  			SECTOR_TO_BLOCK(q->limits.max_discard_sectors);
  	block_t end = lstart + len;
  
  	dc = (struct discard_cmd *)f2fs_lookup_rb_tree_ret(&dcc->root,
  					NULL, lstart,
  					(struct rb_entry **)&prev_dc,
  					(struct rb_entry **)&next_dc,
  					&insert_p, &insert_parent, true, NULL);
  	if (dc)
  		prev_dc = dc;
  
  	if (!prev_dc) {
  		di.lstart = lstart;
  		di.len = next_dc ? next_dc->lstart - lstart : len;
  		di.len = min(di.len, len);
  		di.start = start;
  	}
  
  	while (1) {
  		struct rb_node *node;
  		bool merged = false;
  		struct discard_cmd *tdc = NULL;
  
  		if (prev_dc) {
  			di.lstart = prev_dc->lstart + prev_dc->len;
  			if (di.lstart < lstart)
  				di.lstart = lstart;
  			if (di.lstart >= end)
  				break;
  
  			if (!next_dc || next_dc->lstart > end)
  				di.len = end - di.lstart;
  			else
  				di.len = next_dc->lstart - di.lstart;
  			di.start = start + di.lstart - lstart;
  		}
  
  		if (!di.len)
  			goto next;
  
  		if (prev_dc && prev_dc->state == D_PREP &&
  			prev_dc->bdev == bdev &&
  			__is_discard_back_mergeable(&di, &prev_dc->di,
  							max_discard_blocks)) {
  			prev_dc->di.len += di.len;
  			dcc->undiscard_blks += di.len;
  			__relocate_discard_cmd(dcc, prev_dc);
  			di = prev_dc->di;
  			tdc = prev_dc;
  			merged = true;
  		}
  
  		if (next_dc && next_dc->state == D_PREP &&
  			next_dc->bdev == bdev &&
  			__is_discard_front_mergeable(&di, &next_dc->di,
  							max_discard_blocks)) {
  			next_dc->di.lstart = di.lstart;
  			next_dc->di.len += di.len;
  			next_dc->di.start = di.start;
  			dcc->undiscard_blks += di.len;
  			__relocate_discard_cmd(dcc, next_dc);
  			if (tdc)
  				__remove_discard_cmd(sbi, tdc);
  			merged = true;
  		}
  
  		if (!merged) {
  			__insert_discard_tree(sbi, bdev, di.lstart, di.start,
  							di.len, NULL, NULL);
  		}
   next:
  		prev_dc = next_dc;
  		if (!prev_dc)
  			break;
  
  		node = rb_next(&prev_dc->rb_node);
  		next_dc = rb_entry_safe(node, struct discard_cmd, rb_node);
  	}
  }
  
  static int __queue_discard_cmd(struct f2fs_sb_info *sbi,
  		struct block_device *bdev, block_t blkstart, block_t blklen)
  {
  	block_t lblkstart = blkstart;
  
  	if (!f2fs_bdev_support_discard(bdev))
  		return 0;
  
  	trace_f2fs_queue_discard(bdev, blkstart, blklen);
  
  	if (f2fs_is_multi_device(sbi)) {
  		int devi = f2fs_target_device_index(sbi, blkstart);
  
  		blkstart -= FDEV(devi).start_blk;
  	}
  	mutex_lock(&SM_I(sbi)->dcc_info->cmd_lock);
  	__update_discard_tree_range(sbi, bdev, lblkstart, blkstart, blklen);
  	mutex_unlock(&SM_I(sbi)->dcc_info->cmd_lock);
  	return 0;
  }
  
  static unsigned int __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi,
  					struct discard_policy *dpolicy)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct discard_cmd *prev_dc = NULL, *next_dc = NULL;
  	struct rb_node **insert_p = NULL, *insert_parent = NULL;
  	struct discard_cmd *dc;
  	struct blk_plug plug;
  	unsigned int pos = dcc->next_pos;
  	unsigned int issued = 0;
  	bool io_interrupted = false;
  
  	mutex_lock(&dcc->cmd_lock);
  	dc = (struct discard_cmd *)f2fs_lookup_rb_tree_ret(&dcc->root,
  					NULL, pos,
  					(struct rb_entry **)&prev_dc,
  					(struct rb_entry **)&next_dc,
  					&insert_p, &insert_parent, true, NULL);
  	if (!dc)
  		dc = next_dc;
  
  	blk_start_plug(&plug);
  
  	while (dc) {
  		struct rb_node *node;
  		int err = 0;
  
  		if (dc->state != D_PREP)
  			goto next;
  
  		if (dpolicy->io_aware && !is_idle(sbi, DISCARD_TIME)) {
  			io_interrupted = true;
  			break;
  		}
  
  		dcc->next_pos = dc->lstart + dc->len;
  		err = __submit_discard_cmd(sbi, dpolicy, dc, &issued);
  
  		if (issued >= dpolicy->max_requests)
  			break;
  next:
  		node = rb_next(&dc->rb_node);
  		if (err)
  			__remove_discard_cmd(sbi, dc);
  		dc = rb_entry_safe(node, struct discard_cmd, rb_node);
  	}
  
  	blk_finish_plug(&plug);
  
  	if (!dc)
  		dcc->next_pos = 0;
  
  	mutex_unlock(&dcc->cmd_lock);
  
  	if (!issued && io_interrupted)
  		issued = -1;
  
  	return issued;
  }
  
  static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
  					struct discard_policy *dpolicy)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct list_head *pend_list;
  	struct discard_cmd *dc, *tmp;
  	struct blk_plug plug;
  	int i, issued = 0;
  	bool io_interrupted = false;
  
  	if (dpolicy->timeout)
  		f2fs_update_time(sbi, UMOUNT_DISCARD_TIMEOUT);
  
  	for (i = MAX_PLIST_NUM - 1; i >= 0; i--) {
  		if (dpolicy->timeout &&
  				f2fs_time_over(sbi, UMOUNT_DISCARD_TIMEOUT))
  			break;
  
  		if (i + 1 < dpolicy->granularity)
  			break;
  
  		if (i < DEFAULT_DISCARD_GRANULARITY && dpolicy->ordered)
  			return __issue_discard_cmd_orderly(sbi, dpolicy);
  
  		pend_list = &dcc->pend_list[i];
  
  		mutex_lock(&dcc->cmd_lock);
  		if (list_empty(pend_list))
  			goto next;
  		if (unlikely(dcc->rbtree_check))
  			f2fs_bug_on(sbi, !f2fs_check_rb_tree_consistence(sbi,
  								&dcc->root));
  		blk_start_plug(&plug);
  		list_for_each_entry_safe(dc, tmp, pend_list, list) {
  			f2fs_bug_on(sbi, dc->state != D_PREP);
  
  			if (dpolicy->timeout &&
  				f2fs_time_over(sbi, UMOUNT_DISCARD_TIMEOUT))
  				break;
  
  			if (dpolicy->io_aware && i < dpolicy->io_aware_gran &&
  						!is_idle(sbi, DISCARD_TIME)) {
  				io_interrupted = true;
  				break;
  			}
  
  			__submit_discard_cmd(sbi, dpolicy, dc, &issued);
  
  			if (issued >= dpolicy->max_requests)
  				break;
  		}
  		blk_finish_plug(&plug);
  next:
  		mutex_unlock(&dcc->cmd_lock);
  
  		if (issued >= dpolicy->max_requests || io_interrupted)
  			break;
  	}
  
  	if (!issued && io_interrupted)
  		issued = -1;
  
  	return issued;
  }
  
  static bool __drop_discard_cmd(struct f2fs_sb_info *sbi)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct list_head *pend_list;
  	struct discard_cmd *dc, *tmp;
  	int i;
  	bool dropped = false;
  
  	mutex_lock(&dcc->cmd_lock);
  	for (i = MAX_PLIST_NUM - 1; i >= 0; i--) {
  		pend_list = &dcc->pend_list[i];
  		list_for_each_entry_safe(dc, tmp, pend_list, list) {
  			f2fs_bug_on(sbi, dc->state != D_PREP);
  			__remove_discard_cmd(sbi, dc);
  			dropped = true;
  		}
  	}
  	mutex_unlock(&dcc->cmd_lock);
  
  	return dropped;
  }
  
  void f2fs_drop_discard_cmd(struct f2fs_sb_info *sbi)
  {
  	__drop_discard_cmd(sbi);
  }
  
  static unsigned int __wait_one_discard_bio(struct f2fs_sb_info *sbi,
  							struct discard_cmd *dc)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	unsigned int len = 0;
  
  	wait_for_completion_io(&dc->wait);
  	mutex_lock(&dcc->cmd_lock);
  	f2fs_bug_on(sbi, dc->state != D_DONE);
  	dc->ref--;
  	if (!dc->ref) {
  		if (!dc->error)
  			len = dc->len;
  		__remove_discard_cmd(sbi, dc);
  	}
  	mutex_unlock(&dcc->cmd_lock);
  
  	return len;
  }
  
  static unsigned int __wait_discard_cmd_range(struct f2fs_sb_info *sbi,
  						struct discard_policy *dpolicy,
  						block_t start, block_t end)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct list_head *wait_list = (dpolicy->type == DPOLICY_FSTRIM) ?
  					&(dcc->fstrim_list) : &(dcc->wait_list);
  	struct discard_cmd *dc, *tmp;
  	bool need_wait;
  	unsigned int trimmed = 0;
  
  next:
  	need_wait = false;
  
  	mutex_lock(&dcc->cmd_lock);
  	list_for_each_entry_safe(dc, tmp, wait_list, list) {
  		if (dc->lstart + dc->len <= start || end <= dc->lstart)
  			continue;
  		if (dc->len < dpolicy->granularity)
  			continue;
  		if (dc->state == D_DONE && !dc->ref) {
  			wait_for_completion_io(&dc->wait);
  			if (!dc->error)
  				trimmed += dc->len;
  			__remove_discard_cmd(sbi, dc);
  		} else {
  			dc->ref++;
  			need_wait = true;
  			break;
  		}
  	}
  	mutex_unlock(&dcc->cmd_lock);
  
  	if (need_wait) {
  		trimmed += __wait_one_discard_bio(sbi, dc);
  		goto next;
  	}
  
  	return trimmed;
  }
  
  static unsigned int __wait_all_discard_cmd(struct f2fs_sb_info *sbi,
  						struct discard_policy *dpolicy)
  {
  	struct discard_policy dp;
  	unsigned int discard_blks;
  
  	if (dpolicy)
  		return __wait_discard_cmd_range(sbi, dpolicy, 0, UINT_MAX);
  
  	/* wait all */
  	__init_discard_policy(sbi, &dp, DPOLICY_FSTRIM, 1);
  	discard_blks = __wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);
  	__init_discard_policy(sbi, &dp, DPOLICY_UMOUNT, 1);
  	discard_blks += __wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);
  
  	return discard_blks;
  }
  
  /* This should be covered by global mutex, &sit_i->sentry_lock */
  static void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, block_t blkaddr)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct discard_cmd *dc;
  	bool need_wait = false;
  
  	mutex_lock(&dcc->cmd_lock);
  	dc = (struct discard_cmd *)f2fs_lookup_rb_tree(&dcc->root,
  							NULL, blkaddr);
  	if (dc) {
  		if (dc->state == D_PREP) {
  			__punch_discard_cmd(sbi, dc, blkaddr);
  		} else {
  			dc->ref++;
  			need_wait = true;
  		}
  	}
  	mutex_unlock(&dcc->cmd_lock);
  
  	if (need_wait)
  		__wait_one_discard_bio(sbi, dc);
  }
  
  void f2fs_stop_discard_thread(struct f2fs_sb_info *sbi)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  
  	if (dcc && dcc->f2fs_issue_discard) {
  		struct task_struct *discard_thread = dcc->f2fs_issue_discard;
  
  		dcc->f2fs_issue_discard = NULL;
  		kthread_stop(discard_thread);
  	}
  }
  
  /* This comes from f2fs_put_super */
  bool f2fs_issue_discard_timeout(struct f2fs_sb_info *sbi)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct discard_policy dpolicy;
  	bool dropped;
  
  	__init_discard_policy(sbi, &dpolicy, DPOLICY_UMOUNT,
  					dcc->discard_granularity);
  	__issue_discard_cmd(sbi, &dpolicy);
  	dropped = __drop_discard_cmd(sbi);
  
  	/* just to make sure there is no pending discard commands */
  	__wait_all_discard_cmd(sbi, NULL);
  
  	f2fs_bug_on(sbi, atomic_read(&dcc->discard_cmd_cnt));
  	return dropped;
  }
  
  static int issue_discard_thread(void *data)
  {
  	struct f2fs_sb_info *sbi = data;
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	wait_queue_head_t *q = &dcc->discard_wait_queue;
  	struct discard_policy dpolicy;
  	unsigned int wait_ms = DEF_MIN_DISCARD_ISSUE_TIME;
  	int issued;
  
  	set_freezable();
  
  	do {
  		__init_discard_policy(sbi, &dpolicy, DPOLICY_BG,
  					dcc->discard_granularity);
  
  		wait_event_interruptible_timeout(*q,
  				kthread_should_stop() || freezing(current) ||
  				dcc->discard_wake,
  				msecs_to_jiffies(wait_ms));
  
  		if (dcc->discard_wake)
  			dcc->discard_wake = 0;
  
  		/* clean up pending candidates before going to sleep */
  		if (atomic_read(&dcc->queued_discard))
  			__wait_all_discard_cmd(sbi, NULL);
  
  		if (try_to_freeze())
  			continue;
  		if (f2fs_readonly(sbi->sb))
  			continue;
  		if (kthread_should_stop())
  			return 0;
  		if (is_sbi_flag_set(sbi, SBI_NEED_FSCK)) {
  			wait_ms = dpolicy.max_interval;
  			continue;
  		}
  
  		if (sbi->gc_mode == GC_URGENT)
  			__init_discard_policy(sbi, &dpolicy, DPOLICY_FORCE, 1);
  
  		sb_start_intwrite(sbi->sb);
  
  		issued = __issue_discard_cmd(sbi, &dpolicy);
  		if (issued > 0) {
  			__wait_all_discard_cmd(sbi, &dpolicy);
  			wait_ms = dpolicy.min_interval;
  		} else if (issued == -1){
  			wait_ms = f2fs_time_to_wait(sbi, DISCARD_TIME);
  			if (!wait_ms)
  				wait_ms = dpolicy.mid_interval;
  		} else {
  			wait_ms = dpolicy.max_interval;
  		}
  
  		sb_end_intwrite(sbi->sb);
  
  	} while (!kthread_should_stop());
  	return 0;
  }
  
  #ifdef CONFIG_BLK_DEV_ZONED
  static int __f2fs_issue_discard_zone(struct f2fs_sb_info *sbi,
  		struct block_device *bdev, block_t blkstart, block_t blklen)
  {
  	sector_t sector, nr_sects;
  	block_t lblkstart = blkstart;
  	int devi = 0;
  
  	if (f2fs_is_multi_device(sbi)) {
  		devi = f2fs_target_device_index(sbi, blkstart);
  		if (blkstart < FDEV(devi).start_blk ||
  		    blkstart > FDEV(devi).end_blk) {
  			f2fs_err(sbi, "Invalid block %x", blkstart);
  			return -EIO;
  		}
  		blkstart -= FDEV(devi).start_blk;
  	}
  
  	/* For sequential zones, reset the zone write pointer */
  	if (f2fs_blkz_is_seq(sbi, devi, blkstart)) {
  		sector = SECTOR_FROM_BLOCK(blkstart);
  		nr_sects = SECTOR_FROM_BLOCK(blklen);
  
  		if (sector & (bdev_zone_sectors(bdev) - 1) ||
  				nr_sects != bdev_zone_sectors(bdev)) {
  			f2fs_err(sbi, "(%d) %s: Unaligned zone reset attempted (block %x + %x)",
  				 devi, sbi->s_ndevs ? FDEV(devi).path : "",
  				 blkstart, blklen);
  			return -EIO;
  		}
  		trace_f2fs_issue_reset_zone(bdev, blkstart);
  		return blkdev_zone_mgmt(bdev, REQ_OP_ZONE_RESET,
  					sector, nr_sects, GFP_NOFS);
  	}
  
  	/* For conventional zones, use regular discard if supported */
  	return __queue_discard_cmd(sbi, bdev, lblkstart, blklen);
  }
  #endif
  
  static int __issue_discard_async(struct f2fs_sb_info *sbi,
  		struct block_device *bdev, block_t blkstart, block_t blklen)
  {
  #ifdef CONFIG_BLK_DEV_ZONED
  	if (f2fs_sb_has_blkzoned(sbi) && bdev_is_zoned(bdev))
  		return __f2fs_issue_discard_zone(sbi, bdev, blkstart, blklen);
  #endif
  	return __queue_discard_cmd(sbi, bdev, blkstart, blklen);
  }
  
  static int f2fs_issue_discard(struct f2fs_sb_info *sbi,
  				block_t blkstart, block_t blklen)
  {
  	sector_t start = blkstart, len = 0;
  	struct block_device *bdev;
  	struct seg_entry *se;
  	unsigned int offset;
  	block_t i;
  	int err = 0;
  
  	bdev = f2fs_target_device(sbi, blkstart, NULL);
  
  	for (i = blkstart; i < blkstart + blklen; i++, len++) {
  		if (i != start) {
  			struct block_device *bdev2 =
  				f2fs_target_device(sbi, i, NULL);
  
  			if (bdev2 != bdev) {
  				err = __issue_discard_async(sbi, bdev,
  						start, len);
  				if (err)
  					return err;
  				bdev = bdev2;
  				start = i;
  				len = 0;
  			}
  		}
  
  		se = get_seg_entry(sbi, GET_SEGNO(sbi, i));
  		offset = GET_BLKOFF_FROM_SEG0(sbi, i);
  
  		if (!f2fs_test_and_set_bit(offset, se->discard_map))
  			sbi->discard_blks--;
  	}
  
  	if (len)
  		err = __issue_discard_async(sbi, bdev, start, len);
  	return err;
  }
  
  static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc,
  							bool check_only)
  {
  	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
  	int max_blocks = sbi->blocks_per_seg;
  	struct seg_entry *se = get_seg_entry(sbi, cpc->trim_start);
  	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
  	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
  	unsigned long *discard_map = (unsigned long *)se->discard_map;
  	unsigned long *dmap = SIT_I(sbi)->tmp_map;
  	unsigned int start = 0, end = -1;
  	bool force = (cpc->reason & CP_DISCARD);
  	struct discard_entry *de = NULL;
  	struct list_head *head = &SM_I(sbi)->dcc_info->entry_list;
  	int i;
  
  	if (se->valid_blocks == max_blocks || !f2fs_hw_support_discard(sbi))
  		return false;
  
  	if (!force) {
  		if (!f2fs_realtime_discard_enable(sbi) || !se->valid_blocks ||
  			SM_I(sbi)->dcc_info->nr_discards >=
  				SM_I(sbi)->dcc_info->max_discards)
  			return false;
  	}
  
  	/* SIT_VBLOCK_MAP_SIZE should be multiple of sizeof(unsigned long) */
  	for (i = 0; i < entries; i++)
  		dmap[i] = force ? ~ckpt_map[i] & ~discard_map[i] :
  				(cur_map[i] ^ ckpt_map[i]) & ckpt_map[i];
  
  	while (force || SM_I(sbi)->dcc_info->nr_discards <=
  				SM_I(sbi)->dcc_info->max_discards) {
  		start = __find_rev_next_bit(dmap, max_blocks, end + 1);
  		if (start >= max_blocks)
  			break;
  
  		end = __find_rev_next_zero_bit(dmap, max_blocks, start + 1);
  		if (force && start && end != max_blocks
  					&& (end - start) < cpc->trim_minlen)
  			continue;
  
  		if (check_only)
  			return true;
  
  		if (!de) {
  			de = f2fs_kmem_cache_alloc(discard_entry_slab,
  								GFP_F2FS_ZERO);
  			de->start_blkaddr = START_BLOCK(sbi, cpc->trim_start);
  			list_add_tail(&de->list, head);
  		}
  
  		for (i = start; i < end; i++)
  			__set_bit_le(i, (void *)de->discard_map);
  
  		SM_I(sbi)->dcc_info->nr_discards += end - start;
  	}
  	return false;
  }
  
  static void release_discard_addr(struct discard_entry *entry)
  {
  	list_del(&entry->list);
  	kmem_cache_free(discard_entry_slab, entry);
  }
  
  void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi)
  {
  	struct list_head *head = &(SM_I(sbi)->dcc_info->entry_list);
  	struct discard_entry *entry, *this;
  
  	/* drop caches */
  	list_for_each_entry_safe(entry, this, head, list)
  		release_discard_addr(entry);
  }
  
  /*
   * Should call f2fs_clear_prefree_segments after checkpoint is done.
   */
  static void set_prefree_as_free_segments(struct f2fs_sb_info *sbi)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  	unsigned int segno;
  
  	mutex_lock(&dirty_i->seglist_lock);
  	for_each_set_bit(segno, dirty_i->dirty_segmap[PRE], MAIN_SEGS(sbi))
  		__set_test_and_free(sbi, segno);
  	mutex_unlock(&dirty_i->seglist_lock);
  }
  
  void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
  						struct cp_control *cpc)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct list_head *head = &dcc->entry_list;
  	struct discard_entry *entry, *this;
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  	unsigned long *prefree_map = dirty_i->dirty_segmap[PRE];
  	unsigned int start = 0, end = -1;
  	unsigned int secno, start_segno;
  	bool force = (cpc->reason & CP_DISCARD);
  	bool need_align = f2fs_lfs_mode(sbi) && __is_large_section(sbi);
  
  	mutex_lock(&dirty_i->seglist_lock);
  
  	while (1) {
  		int i;
  
  		if (need_align && end != -1)
  			end--;
  		start = find_next_bit(prefree_map, MAIN_SEGS(sbi), end + 1);
  		if (start >= MAIN_SEGS(sbi))
  			break;
  		end = find_next_zero_bit(prefree_map, MAIN_SEGS(sbi),
  								start + 1);
  
  		if (need_align) {
  			start = rounddown(start, sbi->segs_per_sec);
  			end = roundup(end, sbi->segs_per_sec);
  		}
  
  		for (i = start; i < end; i++) {
  			if (test_and_clear_bit(i, prefree_map))
  				dirty_i->nr_dirty[PRE]--;
  		}
  
  		if (!f2fs_realtime_discard_enable(sbi))
  			continue;
  
  		if (force && start >= cpc->trim_start &&
  					(end - 1) <= cpc->trim_end)
  				continue;
  
  		if (!f2fs_lfs_mode(sbi) || !__is_large_section(sbi)) {
  			f2fs_issue_discard(sbi, START_BLOCK(sbi, start),
  				(end - start) << sbi->log_blocks_per_seg);
  			continue;
  		}
  next:
  		secno = GET_SEC_FROM_SEG(sbi, start);
  		start_segno = GET_SEG_FROM_SEC(sbi, secno);
  		if (!IS_CURSEC(sbi, secno) &&
  			!get_valid_blocks(sbi, start, true))
  			f2fs_issue_discard(sbi, START_BLOCK(sbi, start_segno),
  				sbi->segs_per_sec << sbi->log_blocks_per_seg);
  
  		start = start_segno + sbi->segs_per_sec;
  		if (start < end)
  			goto next;
  		else
  			end = start - 1;
  	}
  	mutex_unlock(&dirty_i->seglist_lock);
  
  	/* send small discards */
  	list_for_each_entry_safe(entry, this, head, list) {
  		unsigned int cur_pos = 0, next_pos, len, total_len = 0;
  		bool is_valid = test_bit_le(0, entry->discard_map);
  
  find_next:
  		if (is_valid) {
  			next_pos = find_next_zero_bit_le(entry->discard_map,
  					sbi->blocks_per_seg, cur_pos);
  			len = next_pos - cur_pos;
  
  			if (f2fs_sb_has_blkzoned(sbi) ||
  			    (force && len < cpc->trim_minlen))
  				goto skip;
  
  			f2fs_issue_discard(sbi, entry->start_blkaddr + cur_pos,
  									len);
  			total_len += len;
  		} else {
  			next_pos = find_next_bit_le(entry->discard_map,
  					sbi->blocks_per_seg, cur_pos);
  		}
  skip:
  		cur_pos = next_pos;
  		is_valid = !is_valid;
  
  		if (cur_pos < sbi->blocks_per_seg)
  			goto find_next;
  
  		release_discard_addr(entry);
  		dcc->nr_discards -= total_len;
  	}
  
  	wake_up_discard_thread(sbi, false);
  }
  
  static int create_discard_cmd_control(struct f2fs_sb_info *sbi)
  {
  	dev_t dev = sbi->sb->s_bdev->bd_dev;
  	struct discard_cmd_control *dcc;
  	int err = 0, i;
  
  	if (SM_I(sbi)->dcc_info) {
  		dcc = SM_I(sbi)->dcc_info;
  		goto init_thread;
  	}
  
  	dcc = f2fs_kzalloc(sbi, sizeof(struct discard_cmd_control), GFP_KERNEL);
  	if (!dcc)
  		return -ENOMEM;
  
  	dcc->discard_granularity = DEFAULT_DISCARD_GRANULARITY;
  	INIT_LIST_HEAD(&dcc->entry_list);
  	for (i = 0; i < MAX_PLIST_NUM; i++)
  		INIT_LIST_HEAD(&dcc->pend_list[i]);
  	INIT_LIST_HEAD(&dcc->wait_list);
  	INIT_LIST_HEAD(&dcc->fstrim_list);
  	mutex_init(&dcc->cmd_lock);
  	atomic_set(&dcc->issued_discard, 0);
  	atomic_set(&dcc->queued_discard, 0);
  	atomic_set(&dcc->discard_cmd_cnt, 0);
  	dcc->nr_discards = 0;
  	dcc->max_discards = MAIN_SEGS(sbi) << sbi->log_blocks_per_seg;
  	dcc->undiscard_blks = 0;
  	dcc->next_pos = 0;
  	dcc->root = RB_ROOT_CACHED;
  	dcc->rbtree_check = false;
  
  	init_waitqueue_head(&dcc->discard_wait_queue);
  	SM_I(sbi)->dcc_info = dcc;
  init_thread:
  	dcc->f2fs_issue_discard = kthread_run(issue_discard_thread, sbi,
  				"f2fs_discard-%u:%u", MAJOR(dev), MINOR(dev));
  	if (IS_ERR(dcc->f2fs_issue_discard)) {
  		err = PTR_ERR(dcc->f2fs_issue_discard);
  		kvfree(dcc);
  		SM_I(sbi)->dcc_info = NULL;
  		return err;
  	}
  
  	return err;
  }
  
  static void destroy_discard_cmd_control(struct f2fs_sb_info *sbi)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  
  	if (!dcc)
  		return;
  
  	f2fs_stop_discard_thread(sbi);
  
  	/*
  	 * Recovery can cache discard commands, so in error path of
  	 * fill_super(), it needs to give a chance to handle them.
  	 */
  	if (unlikely(atomic_read(&dcc->discard_cmd_cnt)))
  		f2fs_issue_discard_timeout(sbi);
  
  	kvfree(dcc);
  	SM_I(sbi)->dcc_info = NULL;
  }
  
  static bool __mark_sit_entry_dirty(struct f2fs_sb_info *sbi, unsigned int segno)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  
  	if (!__test_and_set_bit(segno, sit_i->dirty_sentries_bitmap)) {
  		sit_i->dirty_sentries++;
  		return false;
  	}
  
  	return true;
  }
  
  static void __set_sit_entry_type(struct f2fs_sb_info *sbi, int type,
  					unsigned int segno, int modified)
  {
  	struct seg_entry *se = get_seg_entry(sbi, segno);
  	se->type = type;
  	if (modified)
  		__mark_sit_entry_dirty(sbi, segno);
  }
  
  static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
  {
  	struct seg_entry *se;
  	unsigned int segno, offset;
  	long int new_vblocks;
  	bool exist;
  #ifdef CONFIG_F2FS_CHECK_FS
  	bool mir_exist;
  #endif
  
  	segno = GET_SEGNO(sbi, blkaddr);
  
  	se = get_seg_entry(sbi, segno);
  	new_vblocks = se->valid_blocks + del;
  	offset = GET_BLKOFF_FROM_SEG0(sbi, blkaddr);
  
  	f2fs_bug_on(sbi, (new_vblocks >> (sizeof(unsigned short) << 3) ||
  				(new_vblocks > sbi->blocks_per_seg)));
  
  	se->valid_blocks = new_vblocks;
  	se->mtime = get_mtime(sbi, false);
  	if (se->mtime > SIT_I(sbi)->max_mtime)
  		SIT_I(sbi)->max_mtime = se->mtime;
  
  	/* Update valid block bitmap */
  	if (del > 0) {
  		exist = f2fs_test_and_set_bit(offset, se->cur_valid_map);
  #ifdef CONFIG_F2FS_CHECK_FS
  		mir_exist = f2fs_test_and_set_bit(offset,
  						se->cur_valid_map_mir);
  		if (unlikely(exist != mir_exist)) {
  			f2fs_err(sbi, "Inconsistent error when setting bitmap, blk:%u, old bit:%d",
  				 blkaddr, exist);
  			f2fs_bug_on(sbi, 1);
  		}
  #endif
  		if (unlikely(exist)) {
  			f2fs_err(sbi, "Bitmap was wrongly set, blk:%u",
  				 blkaddr);
  			f2fs_bug_on(sbi, 1);
  			se->valid_blocks--;
  			del = 0;
  		}
  
  		if (!f2fs_test_and_set_bit(offset, se->discard_map))
  			sbi->discard_blks--;
  
  		/*
  		 * SSR should never reuse block which is checkpointed
  		 * or newly invalidated.
  		 */
  		if (!is_sbi_flag_set(sbi, SBI_CP_DISABLED)) {
  			if (!f2fs_test_and_set_bit(offset, se->ckpt_valid_map))
  				se->ckpt_valid_blocks++;
  		}
  	} else {
  		exist = f2fs_test_and_clear_bit(offset, se->cur_valid_map);
  #ifdef CONFIG_F2FS_CHECK_FS
  		mir_exist = f2fs_test_and_clear_bit(offset,
  						se->cur_valid_map_mir);
  		if (unlikely(exist != mir_exist)) {
  			f2fs_err(sbi, "Inconsistent error when clearing bitmap, blk:%u, old bit:%d",
  				 blkaddr, exist);
  			f2fs_bug_on(sbi, 1);
  		}
  #endif
  		if (unlikely(!exist)) {
  			f2fs_err(sbi, "Bitmap was wrongly cleared, blk:%u",
  				 blkaddr);
  			f2fs_bug_on(sbi, 1);
  			se->valid_blocks++;
  			del = 0;
  		} else if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
  			/*
  			 * If checkpoints are off, we must not reuse data that
  			 * was used in the previous checkpoint. If it was used
  			 * before, we must track that to know how much space we
  			 * really have.
  			 */
  			if (f2fs_test_bit(offset, se->ckpt_valid_map)) {
  				spin_lock(&sbi->stat_lock);
  				sbi->unusable_block_count++;
  				spin_unlock(&sbi->stat_lock);
  			}
  		}
  
  		if (f2fs_test_and_clear_bit(offset, se->discard_map))
  			sbi->discard_blks++;
  	}
  	if (!f2fs_test_bit(offset, se->ckpt_valid_map))
  		se->ckpt_valid_blocks += del;
  
  	__mark_sit_entry_dirty(sbi, segno);
  
  	/* update total number of valid blocks to be written in ckpt area */
  	SIT_I(sbi)->written_valid_blocks += del;
  
  	if (__is_large_section(sbi))
  		get_sec_entry(sbi, segno)->valid_blocks += del;
  }
  
  void f2fs_invalidate_blocks(struct f2fs_sb_info *sbi, block_t addr)
  {
  	unsigned int segno = GET_SEGNO(sbi, addr);
  	struct sit_info *sit_i = SIT_I(sbi);
  
  	f2fs_bug_on(sbi, addr == NULL_ADDR);
  	if (addr == NEW_ADDR || addr == COMPRESS_ADDR)
  		return;
  
  	invalidate_mapping_pages(META_MAPPING(sbi), addr, addr);
  
  	/* add it into sit main buffer */
  	down_write(&sit_i->sentry_lock);
  
  	update_sit_entry(sbi, addr, -1);
  
  	/* add it into dirty seglist */
  	locate_dirty_segment(sbi, segno);
  
  	up_write(&sit_i->sentry_lock);
  }
  
  bool f2fs_is_checkpointed_data(struct f2fs_sb_info *sbi, block_t blkaddr)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	unsigned int segno, offset;
  	struct seg_entry *se;
  	bool is_cp = false;
  
  	if (!__is_valid_data_blkaddr(blkaddr))
  		return true;
  
  	down_read(&sit_i->sentry_lock);
  
  	segno = GET_SEGNO(sbi, blkaddr);
  	se = get_seg_entry(sbi, segno);
  	offset = GET_BLKOFF_FROM_SEG0(sbi, blkaddr);
  
  	if (f2fs_test_bit(offset, se->ckpt_valid_map))
  		is_cp = true;
  
  	up_read(&sit_i->sentry_lock);
  
  	return is_cp;
  }
  
  /*
   * This function should be resided under the curseg_mutex lock
   */
  static void __add_sum_entry(struct f2fs_sb_info *sbi, int type,
  					struct f2fs_summary *sum)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	void *addr = curseg->sum_blk;
  	addr += curseg->next_blkoff * sizeof(struct f2fs_summary);
  	memcpy(addr, sum, sizeof(struct f2fs_summary));
  }
  
  /*
   * Calculate the number of current summary pages for writing
   */
  int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra)
  {
  	int valid_sum_count = 0;
  	int i, sum_in_page;
  
  	for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
  		if (sbi->ckpt->alloc_type[i] == SSR)
  			valid_sum_count += sbi->blocks_per_seg;
  		else {
  			if (for_ra)
  				valid_sum_count += le16_to_cpu(
  					F2FS_CKPT(sbi)->cur_data_blkoff[i]);
  			else
  				valid_sum_count += curseg_blkoff(sbi, i);
  		}
  	}
  
  	sum_in_page = (PAGE_SIZE - 2 * SUM_JOURNAL_SIZE -
  			SUM_FOOTER_SIZE) / SUMMARY_SIZE;
  	if (valid_sum_count <= sum_in_page)
  		return 1;
  	else if ((valid_sum_count - sum_in_page) <=
  		(PAGE_SIZE - SUM_FOOTER_SIZE) / SUMMARY_SIZE)
  		return 2;
  	return 3;
  }
  
  /*
   * Caller should put this summary page
   */
  struct page *f2fs_get_sum_page(struct f2fs_sb_info *sbi, unsigned int segno)
  {
  	return f2fs_get_meta_page_nofail(sbi, GET_SUM_BLOCK(sbi, segno));
  }
  
  void f2fs_update_meta_page(struct f2fs_sb_info *sbi,
  					void *src, block_t blk_addr)
  {
  	struct page *page = f2fs_grab_meta_page(sbi, blk_addr);
  
  	memcpy(page_address(page), src, PAGE_SIZE);
  	set_page_dirty(page);
  	f2fs_put_page(page, 1);
  }
  
  static void write_sum_page(struct f2fs_sb_info *sbi,
  			struct f2fs_summary_block *sum_blk, block_t blk_addr)
  {
  	f2fs_update_meta_page(sbi, (void *)sum_blk, blk_addr);
  }
  
  static void write_current_sum_page(struct f2fs_sb_info *sbi,
  						int type, block_t blk_addr)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	struct page *page = f2fs_grab_meta_page(sbi, blk_addr);
  	struct f2fs_summary_block *src = curseg->sum_blk;
  	struct f2fs_summary_block *dst;
  
  	dst = (struct f2fs_summary_block *)page_address(page);
  	memset(dst, 0, PAGE_SIZE);
  
  	mutex_lock(&curseg->curseg_mutex);
  
  	down_read(&curseg->journal_rwsem);
  	memcpy(&dst->journal, curseg->journal, SUM_JOURNAL_SIZE);
  	up_read(&curseg->journal_rwsem);
  
  	memcpy(dst->entries, src->entries, SUM_ENTRY_SIZE);
  	memcpy(&dst->footer, &src->footer, SUM_FOOTER_SIZE);
  
  	mutex_unlock(&curseg->curseg_mutex);
  
  	set_page_dirty(page);
  	f2fs_put_page(page, 1);
  }
  
  static int is_next_segment_free(struct f2fs_sb_info *sbi, int type)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	unsigned int segno = curseg->segno + 1;
  	struct free_segmap_info *free_i = FREE_I(sbi);
  
  	if (segno < MAIN_SEGS(sbi) && segno % sbi->segs_per_sec)
  		return !test_bit(segno, free_i->free_segmap);
  	return 0;
  }
  
  /*
   * Find a new segment from the free segments bitmap to right order
   * This function should be returned with success, otherwise BUG
   */
  static void get_new_segment(struct f2fs_sb_info *sbi,
  			unsigned int *newseg, bool new_sec, int dir)
  {
  	struct free_segmap_info *free_i = FREE_I(sbi);
  	unsigned int segno, secno, zoneno;
  	unsigned int total_zones = MAIN_SECS(sbi) / sbi->secs_per_zone;
  	unsigned int hint = GET_SEC_FROM_SEG(sbi, *newseg);
  	unsigned int old_zoneno = GET_ZONE_FROM_SEG(sbi, *newseg);
  	unsigned int left_start = hint;
  	bool init = true;
  	int go_left = 0;
  	int i;
  
  	spin_lock(&free_i->segmap_lock);
  
  	if (!new_sec && ((*newseg + 1) % sbi->segs_per_sec)) {
  		segno = find_next_zero_bit(free_i->free_segmap,
  			GET_SEG_FROM_SEC(sbi, hint + 1), *newseg + 1);
  		if (segno < GET_SEG_FROM_SEC(sbi, hint + 1))
  			goto got_it;
  	}
  find_other_zone:
  	secno = find_next_zero_bit(free_i->free_secmap, MAIN_SECS(sbi), hint);
  	if (secno >= MAIN_SECS(sbi)) {
  		if (dir == ALLOC_RIGHT) {
  			secno = find_next_zero_bit(free_i->free_secmap,
  							MAIN_SECS(sbi), 0);
  			f2fs_bug_on(sbi, secno >= MAIN_SECS(sbi));
  		} else {
  			go_left = 1;
  			left_start = hint - 1;
  		}
  	}
  	if (go_left == 0)
  		goto skip_left;
  
  	while (test_bit(left_start, free_i->free_secmap)) {
  		if (left_start > 0) {
  			left_start--;
  			continue;
  		}
  		left_start = find_next_zero_bit(free_i->free_secmap,
  							MAIN_SECS(sbi), 0);
  		f2fs_bug_on(sbi, left_start >= MAIN_SECS(sbi));
  		break;
  	}
  	secno = left_start;
  skip_left:
  	segno = GET_SEG_FROM_SEC(sbi, secno);
  	zoneno = GET_ZONE_FROM_SEC(sbi, secno);
  
  	/* give up on finding another zone */
  	if (!init)
  		goto got_it;
  	if (sbi->secs_per_zone == 1)
  		goto got_it;
  	if (zoneno == old_zoneno)
  		goto got_it;
  	if (dir == ALLOC_LEFT) {
  		if (!go_left && zoneno + 1 >= total_zones)
  			goto got_it;
  		if (go_left && zoneno == 0)
  			goto got_it;
  	}
  	for (i = 0; i < NR_CURSEG_TYPE; i++)
  		if (CURSEG_I(sbi, i)->zone == zoneno)
  			break;
  
  	if (i < NR_CURSEG_TYPE) {
  		/* zone is in user, try another */
  		if (go_left)
  			hint = zoneno * sbi->secs_per_zone - 1;
  		else if (zoneno + 1 >= total_zones)
  			hint = 0;
  		else
  			hint = (zoneno + 1) * sbi->secs_per_zone;
  		init = false;
  		goto find_other_zone;
  	}
  got_it:
  	/* set it as dirty segment in free segmap */
  	f2fs_bug_on(sbi, test_bit(segno, free_i->free_segmap));
  	__set_inuse(sbi, segno);
  	*newseg = segno;
  	spin_unlock(&free_i->segmap_lock);
  }
  
  static void reset_curseg(struct f2fs_sb_info *sbi, int type, int modified)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	struct summary_footer *sum_footer;
  
  	curseg->segno = curseg->next_segno;
  	curseg->zone = GET_ZONE_FROM_SEG(sbi, curseg->segno);
  	curseg->next_blkoff = 0;
  	curseg->next_segno = NULL_SEGNO;
  
  	sum_footer = &(curseg->sum_blk->footer);
  	memset(sum_footer, 0, sizeof(struct summary_footer));
  	if (IS_DATASEG(type))
  		SET_SUM_TYPE(sum_footer, SUM_TYPE_DATA);
  	if (IS_NODESEG(type))
  		SET_SUM_TYPE(sum_footer, SUM_TYPE_NODE);
  	__set_sit_entry_type(sbi, type, curseg->segno, modified);
  }
  
  static unsigned int __get_next_segno(struct f2fs_sb_info *sbi, int type)
  {
  	/* if segs_per_sec is large than 1, we need to keep original policy. */
  	if (__is_large_section(sbi))
  		return CURSEG_I(sbi, type)->segno;
  
  	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
  		return 0;
  
  	if (test_opt(sbi, NOHEAP) &&
  		(type == CURSEG_HOT_DATA || IS_NODESEG(type)))
  		return 0;
  
  	if (SIT_I(sbi)->last_victim[ALLOC_NEXT])
  		return SIT_I(sbi)->last_victim[ALLOC_NEXT];
  
  	/* find segments from 0 to reuse freed segments */
  	if (F2FS_OPTION(sbi).alloc_mode == ALLOC_MODE_REUSE)
  		return 0;
  
  	return CURSEG_I(sbi, type)->segno;
  }
  
  /*
   * Allocate a current working segment.
   * This function always allocates a free segment in LFS manner.
   */
  static void new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	unsigned int segno = curseg->segno;
  	int dir = ALLOC_LEFT;
  
  	write_sum_page(sbi, curseg->sum_blk,
  				GET_SUM_BLOCK(sbi, segno));
  	if (type == CURSEG_WARM_DATA || type == CURSEG_COLD_DATA)
  		dir = ALLOC_RIGHT;
  
  	if (test_opt(sbi, NOHEAP))
  		dir = ALLOC_RIGHT;
  
  	segno = __get_next_segno(sbi, type);
  	get_new_segment(sbi, &segno, new_sec, dir);
  	curseg->next_segno = segno;
  	reset_curseg(sbi, type, 1);
  	curseg->alloc_type = LFS;
  }
  
  static void __next_free_blkoff(struct f2fs_sb_info *sbi,
  			struct curseg_info *seg, block_t start)
  {
  	struct seg_entry *se = get_seg_entry(sbi, seg->segno);
  	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
  	unsigned long *target_map = SIT_I(sbi)->tmp_map;
  	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
  	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
  	int i, pos;
  
  	for (i = 0; i < entries; i++)
  		target_map[i] = ckpt_map[i] | cur_map[i];
  
  	pos = __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, start);
  
  	seg->next_blkoff = pos;
  }
  
  /*
   * If a segment is written by LFS manner, next block offset is just obtained
   * by increasing the current block offset. However, if a segment is written by
   * SSR manner, next block offset obtained by calling __next_free_blkoff
   */
  static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
  				struct curseg_info *seg)
  {
  	if (seg->alloc_type == SSR)
  		__next_free_blkoff(sbi, seg, seg->next_blkoff + 1);
  	else
  		seg->next_blkoff++;
  }
  
  /*
   * This function always allocates a used segment(from dirty seglist) by SSR
   * manner, so it should recover the existing segment information of valid blocks
   */
  static void change_curseg(struct f2fs_sb_info *sbi, int type)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	unsigned int new_segno = curseg->next_segno;
  	struct f2fs_summary_block *sum_node;
  	struct page *sum_page;
  
  	write_sum_page(sbi, curseg->sum_blk,
  				GET_SUM_BLOCK(sbi, curseg->segno));
  	__set_test_and_inuse(sbi, new_segno);
  
  	mutex_lock(&dirty_i->seglist_lock);
  	__remove_dirty_segment(sbi, new_segno, PRE);
  	__remove_dirty_segment(sbi, new_segno, DIRTY);
  	mutex_unlock(&dirty_i->seglist_lock);
  
  	reset_curseg(sbi, type, 1);
  	curseg->alloc_type = SSR;
  	__next_free_blkoff(sbi, curseg, 0);
  
  	sum_page = f2fs_get_sum_page(sbi, new_segno);
  	f2fs_bug_on(sbi, IS_ERR(sum_page));
  	sum_node = (struct f2fs_summary_block *)page_address(sum_page);
  	memcpy(curseg->sum_blk, sum_node, SUM_ENTRY_SIZE);
  	f2fs_put_page(sum_page, 1);
  }
  
  static int get_ssr_segment(struct f2fs_sb_info *sbi, int type)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	const struct victim_selection *v_ops = DIRTY_I(sbi)->v_ops;
  	unsigned segno = NULL_SEGNO;
  	int i, cnt;
  	bool reversed = false;
  
  	/* f2fs_need_SSR() already forces to do this */
  	if (v_ops->get_victim(sbi, &segno, BG_GC, type, SSR)) {
  		curseg->next_segno = segno;
  		return 1;
  	}
  
  	/* For node segments, let's do SSR more intensively */
  	if (IS_NODESEG(type)) {
  		if (type >= CURSEG_WARM_NODE) {
  			reversed = true;
  			i = CURSEG_COLD_NODE;
  		} else {
  			i = CURSEG_HOT_NODE;
  		}
  		cnt = NR_CURSEG_NODE_TYPE;
  	} else {
  		if (type >= CURSEG_WARM_DATA) {
  			reversed = true;
  			i = CURSEG_COLD_DATA;
  		} else {
  			i = CURSEG_HOT_DATA;
  		}
  		cnt = NR_CURSEG_DATA_TYPE;
  	}
  
  	for (; cnt-- > 0; reversed ? i-- : i++) {
  		if (i == type)
  			continue;
  		if (v_ops->get_victim(sbi, &segno, BG_GC, i, SSR)) {
  			curseg->next_segno = segno;
  			return 1;
  		}
  	}
  
  	/* find valid_blocks=0 in dirty list */
  	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
  		segno = get_free_segment(sbi);
  		if (segno != NULL_SEGNO) {
  			curseg->next_segno = segno;
  			return 1;
  		}
  	}
  	return 0;
  }
  
  /*
   * flush out current segment and replace it with new segment
   * This function should be returned with success, otherwise BUG
   */
  static void allocate_segment_by_default(struct f2fs_sb_info *sbi,
  						int type, bool force)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  
  	if (force)
  		new_curseg(sbi, type, true);
  	else if (!is_set_ckpt_flags(sbi, CP_CRC_RECOVERY_FLAG) &&
  					type == CURSEG_WARM_NODE)
  		new_curseg(sbi, type, false);
  	else if (curseg->alloc_type == LFS && is_next_segment_free(sbi, type) &&
  			likely(!is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
  		new_curseg(sbi, type, false);
  	else if (f2fs_need_SSR(sbi) && get_ssr_segment(sbi, type))
  		change_curseg(sbi, type);
  	else
  		new_curseg(sbi, type, false);
  
  	stat_inc_seg_type(sbi, curseg);
  }
  
  void allocate_segment_for_resize(struct f2fs_sb_info *sbi, int type,
  					unsigned int start, unsigned int end)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	unsigned int segno;
  
  	down_read(&SM_I(sbi)->curseg_lock);
  	mutex_lock(&curseg->curseg_mutex);
  	down_write(&SIT_I(sbi)->sentry_lock);
  
  	segno = CURSEG_I(sbi, type)->segno;
  	if (segno < start || segno > end)
  		goto unlock;
  
  	if (f2fs_need_SSR(sbi) && get_ssr_segment(sbi, type))
  		change_curseg(sbi, type);
  	else
  		new_curseg(sbi, type, true);
  
  	stat_inc_seg_type(sbi, curseg);
  
  	locate_dirty_segment(sbi, segno);
  unlock:
  	up_write(&SIT_I(sbi)->sentry_lock);
  
  	if (segno != curseg->segno)
  		f2fs_notice(sbi, "For resize: curseg of type %d: %u ==> %u",
  			    type, segno, curseg->segno);
  
  	mutex_unlock(&curseg->curseg_mutex);
  	up_read(&SM_I(sbi)->curseg_lock);
  }
  
  void f2fs_allocate_new_segments(struct f2fs_sb_info *sbi, int type)
  {
  	struct curseg_info *curseg;
  	unsigned int old_segno;
  	int i;
  
  	down_write(&SIT_I(sbi)->sentry_lock);
  
  	for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
  		if (type != NO_CHECK_TYPE && i != type)
  			continue;
  
  		curseg = CURSEG_I(sbi, i);
  		if (type == NO_CHECK_TYPE || curseg->next_blkoff ||
  				get_valid_blocks(sbi, curseg->segno, false) ||
  				get_ckpt_valid_blocks(sbi, curseg->segno)) {
  			old_segno = curseg->segno;
  			SIT_I(sbi)->s_ops->allocate_segment(sbi, i, true);
  			locate_dirty_segment(sbi, old_segno);
  		}
  	}
  
  	up_write(&SIT_I(sbi)->sentry_lock);
  }
  
  static const struct segment_allocation default_salloc_ops = {
  	.allocate_segment = allocate_segment_by_default,
  };
  
  bool f2fs_exist_trim_candidates(struct f2fs_sb_info *sbi,
  						struct cp_control *cpc)
  {
  	__u64 trim_start = cpc->trim_start;
  	bool has_candidate = false;
  
  	down_write(&SIT_I(sbi)->sentry_lock);
  	for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++) {
  		if (add_discard_addrs(sbi, cpc, true)) {
  			has_candidate = true;
  			break;
  		}
  	}
  	up_write(&SIT_I(sbi)->sentry_lock);
  
  	cpc->trim_start = trim_start;
  	return has_candidate;
  }
  
  static unsigned int __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
  					struct discard_policy *dpolicy,
  					unsigned int start, unsigned int end)
  {
  	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
  	struct discard_cmd *prev_dc = NULL, *next_dc = NULL;
  	struct rb_node **insert_p = NULL, *insert_parent = NULL;
  	struct discard_cmd *dc;
  	struct blk_plug plug;
  	int issued;
  	unsigned int trimmed = 0;
  
  next:
  	issued = 0;
  
  	mutex_lock(&dcc->cmd_lock);
  	if (unlikely(dcc->rbtree_check))
  		f2fs_bug_on(sbi, !f2fs_check_rb_tree_consistence(sbi,
  								&dcc->root));
  
  	dc = (struct discard_cmd *)f2fs_lookup_rb_tree_ret(&dcc->root,
  					NULL, start,
  					(struct rb_entry **)&prev_dc,
  					(struct rb_entry **)&next_dc,
  					&insert_p, &insert_parent, true, NULL);
  	if (!dc)
  		dc = next_dc;
  
  	blk_start_plug(&plug);
  
  	while (dc && dc->lstart <= end) {
  		struct rb_node *node;
  		int err = 0;
  
  		if (dc->len < dpolicy->granularity)
  			goto skip;
  
  		if (dc->state != D_PREP) {
  			list_move_tail(&dc->list, &dcc->fstrim_list);
  			goto skip;
  		}
  
  		err = __submit_discard_cmd(sbi, dpolicy, dc, &issued);
  
  		if (issued >= dpolicy->max_requests) {
  			start = dc->lstart + dc->len;
  
  			if (err)
  				__remove_discard_cmd(sbi, dc);
  
  			blk_finish_plug(&plug);
  			mutex_unlock(&dcc->cmd_lock);
  			trimmed += __wait_all_discard_cmd(sbi, NULL);
  			congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
  			goto next;
  		}
  skip:
  		node = rb_next(&dc->rb_node);
  		if (err)
  			__remove_discard_cmd(sbi, dc);
  		dc = rb_entry_safe(node, struct discard_cmd, rb_node);
  
  		if (fatal_signal_pending(current))
  			break;
  	}
  
  	blk_finish_plug(&plug);
  	mutex_unlock(&dcc->cmd_lock);
  
  	return trimmed;
  }
  
  int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
  {
  	__u64 start = F2FS_BYTES_TO_BLK(range->start);
  	__u64 end = start + F2FS_BYTES_TO_BLK(range->len) - 1;
  	unsigned int start_segno, end_segno;
  	block_t start_block, end_block;
  	struct cp_control cpc;
  	struct discard_policy dpolicy;
  	unsigned long long trimmed = 0;
  	int err = 0;
  	bool need_align = f2fs_lfs_mode(sbi) && __is_large_section(sbi);
  
  	if (start >= MAX_BLKADDR(sbi) || range->len < sbi->blocksize)
  		return -EINVAL;
  
  	if (end < MAIN_BLKADDR(sbi))
  		goto out;
  
  	if (is_sbi_flag_set(sbi, SBI_NEED_FSCK)) {
  		f2fs_warn(sbi, "Found FS corruption, run fsck to fix.");
  		return -EFSCORRUPTED;
  	}
  
  	/* start/end segment number in main_area */
  	start_segno = (start <= MAIN_BLKADDR(sbi)) ? 0 : GET_SEGNO(sbi, start);
  	end_segno = (end >= MAX_BLKADDR(sbi)) ? MAIN_SEGS(sbi) - 1 :
  						GET_SEGNO(sbi, end);
  	if (need_align) {
  		start_segno = rounddown(start_segno, sbi->segs_per_sec);
  		end_segno = roundup(end_segno + 1, sbi->segs_per_sec) - 1;
  	}
  
  	cpc.reason = CP_DISCARD;
  	cpc.trim_minlen = max_t(__u64, 1, F2FS_BYTES_TO_BLK(range->minlen));
  	cpc.trim_start = start_segno;
  	cpc.trim_end = end_segno;
  
  	if (sbi->discard_blks == 0)
  		goto out;
  
  	down_write(&sbi->gc_lock);
  	err = f2fs_write_checkpoint(sbi, &cpc);
  	up_write(&sbi->gc_lock);
  	if (err)
  		goto out;
  
  	/*
  	 * We filed discard candidates, but actually we don't need to wait for
  	 * all of them, since they'll be issued in idle time along with runtime
  	 * discard option. User configuration looks like using runtime discard
  	 * or periodic fstrim instead of it.
  	 */
  	if (f2fs_realtime_discard_enable(sbi))
  		goto out;
  
  	start_block = START_BLOCK(sbi, start_segno);
  	end_block = START_BLOCK(sbi, end_segno + 1);
  
  	__init_discard_policy(sbi, &dpolicy, DPOLICY_FSTRIM, cpc.trim_minlen);
  	trimmed = __issue_discard_cmd_range(sbi, &dpolicy,
  					start_block, end_block);
  
  	trimmed += __wait_discard_cmd_range(sbi, &dpolicy,
  					start_block, end_block);
  out:
  	if (!err)
  		range->len = F2FS_BLK_TO_BYTES(trimmed);
  	return err;
  }
  
  static bool __has_curseg_space(struct f2fs_sb_info *sbi, int type)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	if (curseg->next_blkoff < sbi->blocks_per_seg)
  		return true;
  	return false;
  }
  
  int f2fs_rw_hint_to_seg_type(enum rw_hint hint)
  {
  	switch (hint) {
  	case WRITE_LIFE_SHORT:
  		return CURSEG_HOT_DATA;
  	case WRITE_LIFE_EXTREME:
  		return CURSEG_COLD_DATA;
  	default:
  		return CURSEG_WARM_DATA;
  	}
  }
  
  /* This returns write hints for each segment type. This hints will be
   * passed down to block layer. There are mapping tables which depend on
   * the mount option 'whint_mode'.
   *
   * 1) whint_mode=off. F2FS only passes down WRITE_LIFE_NOT_SET.
   *
   * 2) whint_mode=user-based. F2FS tries to pass down hints given by users.
   *
   * User                  F2FS                     Block
   * ----                  ----                     -----
   *                       META                     WRITE_LIFE_NOT_SET
   *                       HOT_NODE                 "
   *                       WARM_NODE                "
   *                       COLD_NODE                "
   * ioctl(COLD)           COLD_DATA                WRITE_LIFE_EXTREME
   * extension list        "                        "
   *
   * -- buffered io
   * WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME
   * WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT
   * WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_NOT_SET
   * WRITE_LIFE_NONE       "                        "
   * WRITE_LIFE_MEDIUM     "                        "
   * WRITE_LIFE_LONG       "                        "
   *
   * -- direct io
   * WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME
   * WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT
   * WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_NOT_SET
   * WRITE_LIFE_NONE       "                        WRITE_LIFE_NONE
   * WRITE_LIFE_MEDIUM     "                        WRITE_LIFE_MEDIUM
   * WRITE_LIFE_LONG       "                        WRITE_LIFE_LONG
   *
   * 3) whint_mode=fs-based. F2FS passes down hints with its policy.
   *
   * User                  F2FS                     Block
   * ----                  ----                     -----
   *                       META                     WRITE_LIFE_MEDIUM;
   *                       HOT_NODE                 WRITE_LIFE_NOT_SET
   *                       WARM_NODE                "
   *                       COLD_NODE                WRITE_LIFE_NONE
   * ioctl(COLD)           COLD_DATA                WRITE_LIFE_EXTREME
   * extension list        "                        "
   *
   * -- buffered io
   * WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME
   * WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT
   * WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_LONG
   * WRITE_LIFE_NONE       "                        "
   * WRITE_LIFE_MEDIUM     "                        "
   * WRITE_LIFE_LONG       "                        "
   *
   * -- direct io
   * WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME
   * WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT
   * WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_NOT_SET
   * WRITE_LIFE_NONE       "                        WRITE_LIFE_NONE
   * WRITE_LIFE_MEDIUM     "                        WRITE_LIFE_MEDIUM
   * WRITE_LIFE_LONG       "                        WRITE_LIFE_LONG
   */
  
  enum rw_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
  				enum page_type type, enum temp_type temp)
  {
  	if (F2FS_OPTION(sbi).whint_mode == WHINT_MODE_USER) {
  		if (type == DATA) {
  			if (temp == WARM)
  				return WRITE_LIFE_NOT_SET;
  			else if (temp == HOT)
  				return WRITE_LIFE_SHORT;
  			else if (temp == COLD)
  				return WRITE_LIFE_EXTREME;
  		} else {
  			return WRITE_LIFE_NOT_SET;
  		}
  	} else if (F2FS_OPTION(sbi).whint_mode == WHINT_MODE_FS) {
  		if (type == DATA) {
  			if (temp == WARM)
  				return WRITE_LIFE_LONG;
  			else if (temp == HOT)
  				return WRITE_LIFE_SHORT;
  			else if (temp == COLD)
  				return WRITE_LIFE_EXTREME;
  		} else if (type == NODE) {
  			if (temp == WARM || temp == HOT)
  				return WRITE_LIFE_NOT_SET;
  			else if (temp == COLD)
  				return WRITE_LIFE_NONE;
  		} else if (type == META) {
  			return WRITE_LIFE_MEDIUM;
  		}
  	}
  	return WRITE_LIFE_NOT_SET;
  }
  
  static int __get_segment_type_2(struct f2fs_io_info *fio)
  {
  	if (fio->type == DATA)
  		return CURSEG_HOT_DATA;
  	else
  		return CURSEG_HOT_NODE;
  }
  
  static int __get_segment_type_4(struct f2fs_io_info *fio)
  {
  	if (fio->type == DATA) {
  		struct inode *inode = fio->page->mapping->host;
  
  		if (S_ISDIR(inode->i_mode))
  			return CURSEG_HOT_DATA;
  		else
  			return CURSEG_COLD_DATA;
  	} else {
  		if (IS_DNODE(fio->page) && is_cold_node(fio->page))
  			return CURSEG_WARM_NODE;
  		else
  			return CURSEG_COLD_NODE;
  	}
  }
  
  static int __get_segment_type_6(struct f2fs_io_info *fio)
  {
  	if (fio->type == DATA) {
  		struct inode *inode = fio->page->mapping->host;
  
  		if (is_cold_data(fio->page) || file_is_cold(inode) ||
  				f2fs_compressed_file(inode))
  			return CURSEG_COLD_DATA;
  		if (file_is_hot(inode) ||
  				is_inode_flag_set(inode, FI_HOT_DATA) ||
  				f2fs_is_atomic_file(inode) ||
  				f2fs_is_volatile_file(inode))
  			return CURSEG_HOT_DATA;
  		return f2fs_rw_hint_to_seg_type(inode->i_write_hint);
  	} else {
  		if (IS_DNODE(fio->page))
  			return is_cold_node(fio->page) ? CURSEG_WARM_NODE :
  						CURSEG_HOT_NODE;
  		return CURSEG_COLD_NODE;
  	}
  }
  
  static int __get_segment_type(struct f2fs_io_info *fio)
  {
  	int type = 0;
  
  	switch (F2FS_OPTION(fio->sbi).active_logs) {
  	case 2:
  		type = __get_segment_type_2(fio);
  		break;
  	case 4:
  		type = __get_segment_type_4(fio);
  		break;
  	case 6:
  		type = __get_segment_type_6(fio);
  		break;
  	default:
  		f2fs_bug_on(fio->sbi, true);
  	}
  
  	if (IS_HOT(type))
  		fio->temp = HOT;
  	else if (IS_WARM(type))
  		fio->temp = WARM;
  	else
  		fio->temp = COLD;
  	return type;
  }
  
  void f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
  		block_t old_blkaddr, block_t *new_blkaddr,
  		struct f2fs_summary *sum, int type,
  		struct f2fs_io_info *fio, bool add_list)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	struct curseg_info *curseg = CURSEG_I(sbi, type);
  	bool put_pin_sem = false;
  
  	if (type == CURSEG_COLD_DATA) {
  		/* GC during CURSEG_COLD_DATA_PINNED allocation */
  		if (down_read_trylock(&sbi->pin_sem)) {
  			put_pin_sem = true;
  		} else {
  			type = CURSEG_WARM_DATA;
  			curseg = CURSEG_I(sbi, type);
  		}
  	} else if (type == CURSEG_COLD_DATA_PINNED) {
  		type = CURSEG_COLD_DATA;
  	}
  
  	down_read(&SM_I(sbi)->curseg_lock);
  
  	mutex_lock(&curseg->curseg_mutex);
  	down_write(&sit_i->sentry_lock);
  
  	*new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
  
  	f2fs_wait_discard_bio(sbi, *new_blkaddr);
  
  	/*
  	 * __add_sum_entry should be resided under the curseg_mutex
  	 * because, this function updates a summary entry in the
  	 * current summary block.
  	 */
  	__add_sum_entry(sbi, type, sum);
  
  	__refresh_next_blkoff(sbi, curseg);
  
  	stat_inc_block_count(sbi, curseg);
  
  	/*
  	 * SIT information should be updated before segment allocation,
  	 * since SSR needs latest valid block information.
  	 */
  	update_sit_entry(sbi, *new_blkaddr, 1);
  	if (GET_SEGNO(sbi, old_blkaddr) != NULL_SEGNO)
  		update_sit_entry(sbi, old_blkaddr, -1);
  
  	if (!__has_curseg_space(sbi, type))
  		sit_i->s_ops->allocate_segment(sbi, type, false);
  
  	/*
  	 * segment dirty status should be updated after segment allocation,
  	 * so we just need to update status only one time after previous
  	 * segment being closed.
  	 */
  	locate_dirty_segment(sbi, GET_SEGNO(sbi, old_blkaddr));
  	locate_dirty_segment(sbi, GET_SEGNO(sbi, *new_blkaddr));
  
  	up_write(&sit_i->sentry_lock);
  
  	if (page && IS_NODESEG(type)) {
  		fill_node_footer_blkaddr(page, NEXT_FREE_BLKADDR(sbi, curseg));
  
  		f2fs_inode_chksum_set(sbi, page);
  	}
  
  	if (F2FS_IO_ALIGNED(sbi))
  		fio->retry = false;
  
  	if (add_list) {
  		struct f2fs_bio_info *io;
  
  		INIT_LIST_HEAD(&fio->list);
  		fio->in_list = true;
  		io = sbi->write_io[fio->type] + fio->temp;
  		spin_lock(&io->io_lock);
  		list_add_tail(&fio->list, &io->io_list);
  		spin_unlock(&io->io_lock);
  	}
  
  	mutex_unlock(&curseg->curseg_mutex);
  
  	up_read(&SM_I(sbi)->curseg_lock);
  
  	if (put_pin_sem)
  		up_read(&sbi->pin_sem);
  }
  
  static void update_device_state(struct f2fs_io_info *fio)
  {
  	struct f2fs_sb_info *sbi = fio->sbi;
  	unsigned int devidx;
  
  	if (!f2fs_is_multi_device(sbi))
  		return;
  
  	devidx = f2fs_target_device_index(sbi, fio->new_blkaddr);
  
  	/* update device state for fsync */
  	f2fs_set_dirty_device(sbi, fio->ino, devidx, FLUSH_INO);
  
  	/* update device state for checkpoint */
  	if (!f2fs_test_bit(devidx, (char *)&sbi->dirty_device)) {
  		spin_lock(&sbi->dev_lock);
  		f2fs_set_bit(devidx, (char *)&sbi->dirty_device);
  		spin_unlock(&sbi->dev_lock);
  	}
  }
  
  static void do_write_page(struct f2fs_summary *sum, struct f2fs_io_info *fio)
  {
  	int type = __get_segment_type(fio);
  	bool keep_order = (f2fs_lfs_mode(fio->sbi) && type == CURSEG_COLD_DATA);
  
  	if (keep_order)
  		down_read(&fio->sbi->io_order_lock);
  reallocate:
  	f2fs_allocate_data_block(fio->sbi, fio->page, fio->old_blkaddr,
  			&fio->new_blkaddr, sum, type, fio, true);
  	if (GET_SEGNO(fio->sbi, fio->old_blkaddr) != NULL_SEGNO)
  		invalidate_mapping_pages(META_MAPPING(fio->sbi),
  					fio->old_blkaddr, fio->old_blkaddr);
  
  	/* writeout dirty page into bdev */
  	f2fs_submit_page_write(fio);
  	if (fio->retry) {
  		fio->old_blkaddr = fio->new_blkaddr;
  		goto reallocate;
  	}
  
  	update_device_state(fio);
  
  	if (keep_order)
  		up_read(&fio->sbi->io_order_lock);
  }
  
  void f2fs_do_write_meta_page(struct f2fs_sb_info *sbi, struct page *page,
  					enum iostat_type io_type)
  {
  	struct f2fs_io_info fio = {
  		.sbi = sbi,
  		.type = META,
  		.temp = HOT,
  		.op = REQ_OP_WRITE,
  		.op_flags = REQ_SYNC | REQ_META | REQ_PRIO,
  		.old_blkaddr = page->index,
  		.new_blkaddr = page->index,
  		.page = page,
  		.encrypted_page = NULL,
  		.in_list = false,
  	};
  
  	if (unlikely(page->index >= MAIN_BLKADDR(sbi)))
  		fio.op_flags &= ~REQ_META;
  
  	set_page_writeback(page);
  	ClearPageError(page);
  	f2fs_submit_page_write(&fio);
  
  	stat_inc_meta_count(sbi, page->index);
  	f2fs_update_iostat(sbi, io_type, F2FS_BLKSIZE);
  }
  
  void f2fs_do_write_node_page(unsigned int nid, struct f2fs_io_info *fio)
  {
  	struct f2fs_summary sum;
  
  	set_summary(&sum, nid, 0, 0);
  	do_write_page(&sum, fio);
  
  	f2fs_update_iostat(fio->sbi, fio->io_type, F2FS_BLKSIZE);
  }
  
  void f2fs_outplace_write_data(struct dnode_of_data *dn,
  					struct f2fs_io_info *fio)
  {
  	struct f2fs_sb_info *sbi = fio->sbi;
  	struct f2fs_summary sum;
  
  	f2fs_bug_on(sbi, dn->data_blkaddr == NULL_ADDR);
  	set_summary(&sum, dn->nid, dn->ofs_in_node, fio->version);
  	do_write_page(&sum, fio);
  	f2fs_update_data_blkaddr(dn, fio->new_blkaddr);
  
  	f2fs_update_iostat(sbi, fio->io_type, F2FS_BLKSIZE);
  }
  
  int f2fs_inplace_write_data(struct f2fs_io_info *fio)
  {
  	int err;
  	struct f2fs_sb_info *sbi = fio->sbi;
  	unsigned int segno;
  
  	fio->new_blkaddr = fio->old_blkaddr;
  	/* i/o temperature is needed for passing down write hints */
  	__get_segment_type(fio);
  
  	segno = GET_SEGNO(sbi, fio->new_blkaddr);
  
  	if (!IS_DATASEG(get_seg_entry(sbi, segno)->type)) {
  		set_sbi_flag(sbi, SBI_NEED_FSCK);
  		f2fs_warn(sbi, "%s: incorrect segment(%u) type, run fsck to fix.",
  			  __func__, segno);
  		return -EFSCORRUPTED;
  	}
  
  	stat_inc_inplace_blocks(fio->sbi);
  
  	if (fio->bio && !(SM_I(sbi)->ipu_policy & (1 << F2FS_IPU_NOCACHE)))
  		err = f2fs_merge_page_bio(fio);
  	else
  		err = f2fs_submit_page_bio(fio);
  	if (!err) {
  		update_device_state(fio);
  		f2fs_update_iostat(fio->sbi, fio->io_type, F2FS_BLKSIZE);
  	}
  
  	return err;
  }
  
  static inline int __f2fs_get_curseg(struct f2fs_sb_info *sbi,
  						unsigned int segno)
  {
  	int i;
  
  	for (i = CURSEG_HOT_DATA; i < NO_CHECK_TYPE; i++) {
  		if (CURSEG_I(sbi, i)->segno == segno)
  			break;
  	}
  	return i;
  }
  
  void f2fs_do_replace_block(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
  				block_t old_blkaddr, block_t new_blkaddr,
  				bool recover_curseg, bool recover_newaddr)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	struct curseg_info *curseg;
  	unsigned int segno, old_cursegno;
  	struct seg_entry *se;
  	int type;
  	unsigned short old_blkoff;
  
  	segno = GET_SEGNO(sbi, new_blkaddr);
  	se = get_seg_entry(sbi, segno);
  	type = se->type;
  
  	down_write(&SM_I(sbi)->curseg_lock);
  
  	if (!recover_curseg) {
  		/* for recovery flow */
  		if (se->valid_blocks == 0 && !IS_CURSEG(sbi, segno)) {
  			if (old_blkaddr == NULL_ADDR)
  				type = CURSEG_COLD_DATA;
  			else
  				type = CURSEG_WARM_DATA;
  		}
  	} else {
  		if (IS_CURSEG(sbi, segno)) {
  			/* se->type is volatile as SSR allocation */
  			type = __f2fs_get_curseg(sbi, segno);
  			f2fs_bug_on(sbi, type == NO_CHECK_TYPE);
  		} else {
  			type = CURSEG_WARM_DATA;
  		}
  	}
  
  	f2fs_bug_on(sbi, !IS_DATASEG(type));
  	curseg = CURSEG_I(sbi, type);
  
  	mutex_lock(&curseg->curseg_mutex);
  	down_write(&sit_i->sentry_lock);
  
  	old_cursegno = curseg->segno;
  	old_blkoff = curseg->next_blkoff;
  
  	/* change the current segment */
  	if (segno != curseg->segno) {
  		curseg->next_segno = segno;
  		change_curseg(sbi, type);
  	}
  
  	curseg->next_blkoff = GET_BLKOFF_FROM_SEG0(sbi, new_blkaddr);
  	__add_sum_entry(sbi, type, sum);
  
  	if (!recover_curseg || recover_newaddr)
  		update_sit_entry(sbi, new_blkaddr, 1);
  	if (GET_SEGNO(sbi, old_blkaddr) != NULL_SEGNO) {
  		invalidate_mapping_pages(META_MAPPING(sbi),
  					old_blkaddr, old_blkaddr);
  		update_sit_entry(sbi, old_blkaddr, -1);
  	}
  
  	locate_dirty_segment(sbi, GET_SEGNO(sbi, old_blkaddr));
  	locate_dirty_segment(sbi, GET_SEGNO(sbi, new_blkaddr));
  
  	locate_dirty_segment(sbi, old_cursegno);
  
  	if (recover_curseg) {
  		if (old_cursegno != curseg->segno) {
  			curseg->next_segno = old_cursegno;
  			change_curseg(sbi, type);
  		}
  		curseg->next_blkoff = old_blkoff;
  	}
  
  	up_write(&sit_i->sentry_lock);
  	mutex_unlock(&curseg->curseg_mutex);
  	up_write(&SM_I(sbi)->curseg_lock);
  }
  
  void f2fs_replace_block(struct f2fs_sb_info *sbi, struct dnode_of_data *dn,
  				block_t old_addr, block_t new_addr,
  				unsigned char version, bool recover_curseg,
  				bool recover_newaddr)
  {
  	struct f2fs_summary sum;
  
  	set_summary(&sum, dn->nid, dn->ofs_in_node, version);
  
  	f2fs_do_replace_block(sbi, &sum, old_addr, new_addr,
  					recover_curseg, recover_newaddr);
  
  	f2fs_update_data_blkaddr(dn, new_addr);
  }
  
  void f2fs_wait_on_page_writeback(struct page *page,
  				enum page_type type, bool ordered, bool locked)
  {
  	if (PageWriteback(page)) {
  		struct f2fs_sb_info *sbi = F2FS_P_SB(page);
  
  		/* submit cached LFS IO */
  		f2fs_submit_merged_write_cond(sbi, NULL, page, 0, type);
  		/* sbumit cached IPU IO */
  		f2fs_submit_merged_ipu_write(sbi, NULL, page);
  		if (ordered) {
  			wait_on_page_writeback(page);
  			f2fs_bug_on(sbi, locked && PageWriteback(page));
  		} else {
  			wait_for_stable_page(page);
  		}
  	}
  }
  
  void f2fs_wait_on_block_writeback(struct inode *inode, block_t blkaddr)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	struct page *cpage;
  
  	if (!f2fs_post_read_required(inode))
  		return;
  
  	if (!__is_valid_data_blkaddr(blkaddr))
  		return;
  
  	cpage = find_lock_page(META_MAPPING(sbi), blkaddr);
  	if (cpage) {
  		f2fs_wait_on_page_writeback(cpage, DATA, true, true);
  		f2fs_put_page(cpage, 1);
  	}
  }
  
  void f2fs_wait_on_block_writeback_range(struct inode *inode, block_t blkaddr,
  								block_t len)
  {
  	block_t i;
  
  	for (i = 0; i < len; i++)
  		f2fs_wait_on_block_writeback(inode, blkaddr + i);
  }
  
  static int read_compacted_summaries(struct f2fs_sb_info *sbi)
  {
  	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
  	struct curseg_info *seg_i;
  	unsigned char *kaddr;
  	struct page *page;
  	block_t start;
  	int i, j, offset;
  
  	start = start_sum_block(sbi);
  
  	page = f2fs_get_meta_page(sbi, start++);
  	if (IS_ERR(page))
  		return PTR_ERR(page);
  	kaddr = (unsigned char *)page_address(page);
  
  	/* Step 1: restore nat cache */
  	seg_i = CURSEG_I(sbi, CURSEG_HOT_DATA);
  	memcpy(seg_i->journal, kaddr, SUM_JOURNAL_SIZE);
  
  	/* Step 2: restore sit cache */
  	seg_i = CURSEG_I(sbi, CURSEG_COLD_DATA);
  	memcpy(seg_i->journal, kaddr + SUM_JOURNAL_SIZE, SUM_JOURNAL_SIZE);
  	offset = 2 * SUM_JOURNAL_SIZE;
  
  	/* Step 3: restore summary entries */
  	for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
  		unsigned short blk_off;
  		unsigned int segno;
  
  		seg_i = CURSEG_I(sbi, i);
  		segno = le32_to_cpu(ckpt->cur_data_segno[i]);
  		blk_off = le16_to_cpu(ckpt->cur_data_blkoff[i]);
  		seg_i->next_segno = segno;
  		reset_curseg(sbi, i, 0);
  		seg_i->alloc_type = ckpt->alloc_type[i];
  		seg_i->next_blkoff = blk_off;
  
  		if (seg_i->alloc_type == SSR)
  			blk_off = sbi->blocks_per_seg;
  
  		for (j = 0; j < blk_off; j++) {
  			struct f2fs_summary *s;
  			s = (struct f2fs_summary *)(kaddr + offset);
  			seg_i->sum_blk->entries[j] = *s;
  			offset += SUMMARY_SIZE;
  			if (offset + SUMMARY_SIZE <= PAGE_SIZE -
  						SUM_FOOTER_SIZE)
  				continue;
  
  			f2fs_put_page(page, 1);
  			page = NULL;
  
  			page = f2fs_get_meta_page(sbi, start++);
  			if (IS_ERR(page))
  				return PTR_ERR(page);
  			kaddr = (unsigned char *)page_address(page);
  			offset = 0;
  		}
  	}
  	f2fs_put_page(page, 1);
  	return 0;
  }
  
  static int read_normal_summaries(struct f2fs_sb_info *sbi, int type)
  {
  	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
  	struct f2fs_summary_block *sum;
  	struct curseg_info *curseg;
  	struct page *new;
  	unsigned short blk_off;
  	unsigned int segno = 0;
  	block_t blk_addr = 0;
  	int err = 0;
  
  	/* get segment number and block addr */
  	if (IS_DATASEG(type)) {
  		segno = le32_to_cpu(ckpt->cur_data_segno[type]);
  		blk_off = le16_to_cpu(ckpt->cur_data_blkoff[type -
  							CURSEG_HOT_DATA]);
  		if (__exist_node_summaries(sbi))
  			blk_addr = sum_blk_addr(sbi, NR_CURSEG_TYPE, type);
  		else
  			blk_addr = sum_blk_addr(sbi, NR_CURSEG_DATA_TYPE, type);
  	} else {
  		segno = le32_to_cpu(ckpt->cur_node_segno[type -
  							CURSEG_HOT_NODE]);
  		blk_off = le16_to_cpu(ckpt->cur_node_blkoff[type -
  							CURSEG_HOT_NODE]);
  		if (__exist_node_summaries(sbi))
  			blk_addr = sum_blk_addr(sbi, NR_CURSEG_NODE_TYPE,
  							type - CURSEG_HOT_NODE);
  		else
  			blk_addr = GET_SUM_BLOCK(sbi, segno);
  	}
  
  	new = f2fs_get_meta_page(sbi, blk_addr);
  	if (IS_ERR(new))
  		return PTR_ERR(new);
  	sum = (struct f2fs_summary_block *)page_address(new);
  
  	if (IS_NODESEG(type)) {
  		if (__exist_node_summaries(sbi)) {
  			struct f2fs_summary *ns = &sum->entries[0];
  			int i;
  			for (i = 0; i < sbi->blocks_per_seg; i++, ns++) {
  				ns->version = 0;
  				ns->ofs_in_node = 0;
  			}
  		} else {
  			err = f2fs_restore_node_summary(sbi, segno, sum);
  			if (err)
  				goto out;
  		}
  	}
  
  	/* set uncompleted segment to curseg */
  	curseg = CURSEG_I(sbi, type);
  	mutex_lock(&curseg->curseg_mutex);
  
  	/* update journal info */
  	down_write(&curseg->journal_rwsem);
  	memcpy(curseg->journal, &sum->journal, SUM_JOURNAL_SIZE);
  	up_write(&curseg->journal_rwsem);
  
  	memcpy(curseg->sum_blk->entries, sum->entries, SUM_ENTRY_SIZE);
  	memcpy(&curseg->sum_blk->footer, &sum->footer, SUM_FOOTER_SIZE);
  	curseg->next_segno = segno;
  	reset_curseg(sbi, type, 0);
  	curseg->alloc_type = ckpt->alloc_type[type];
  	curseg->next_blkoff = blk_off;
  	mutex_unlock(&curseg->curseg_mutex);
  out:
  	f2fs_put_page(new, 1);
  	return err;
  }
  
  static int restore_curseg_summaries(struct f2fs_sb_info *sbi)
  {
  	struct f2fs_journal *sit_j = CURSEG_I(sbi, CURSEG_COLD_DATA)->journal;
  	struct f2fs_journal *nat_j = CURSEG_I(sbi, CURSEG_HOT_DATA)->journal;
  	int type = CURSEG_HOT_DATA;
  	int err;
  
  	if (is_set_ckpt_flags(sbi, CP_COMPACT_SUM_FLAG)) {
  		int npages = f2fs_npages_for_summary_flush(sbi, true);
  
  		if (npages >= 2)
  			f2fs_ra_meta_pages(sbi, start_sum_block(sbi), npages,
  							META_CP, true);
  
  		/* restore for compacted data summary */
  		err = read_compacted_summaries(sbi);
  		if (err)
  			return err;
  		type = CURSEG_HOT_NODE;
  	}
  
  	if (__exist_node_summaries(sbi))
  		f2fs_ra_meta_pages(sbi, sum_blk_addr(sbi, NR_CURSEG_TYPE, type),
  					NR_CURSEG_TYPE - type, META_CP, true);
  
  	for (; type <= CURSEG_COLD_NODE; type++) {
  		err = read_normal_summaries(sbi, type);
  		if (err)
  			return err;
  	}
  
  	/* sanity check for summary blocks */
  	if (nats_in_cursum(nat_j) > NAT_JOURNAL_ENTRIES ||
  			sits_in_cursum(sit_j) > SIT_JOURNAL_ENTRIES) {
  		f2fs_err(sbi, "invalid journal entries nats %u sits %u\n",
  			 nats_in_cursum(nat_j), sits_in_cursum(sit_j));
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  static void write_compacted_summaries(struct f2fs_sb_info *sbi, block_t blkaddr)
  {
  	struct page *page;
  	unsigned char *kaddr;
  	struct f2fs_summary *summary;
  	struct curseg_info *seg_i;
  	int written_size = 0;
  	int i, j;
  
  	page = f2fs_grab_meta_page(sbi, blkaddr++);
  	kaddr = (unsigned char *)page_address(page);
  	memset(kaddr, 0, PAGE_SIZE);
  
  	/* Step 1: write nat cache */
  	seg_i = CURSEG_I(sbi, CURSEG_HOT_DATA);
  	memcpy(kaddr, seg_i->journal, SUM_JOURNAL_SIZE);
  	written_size += SUM_JOURNAL_SIZE;
  
  	/* Step 2: write sit cache */
  	seg_i = CURSEG_I(sbi, CURSEG_COLD_DATA);
  	memcpy(kaddr + written_size, seg_i->journal, SUM_JOURNAL_SIZE);
  	written_size += SUM_JOURNAL_SIZE;
  
  	/* Step 3: write summary entries */
  	for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
  		unsigned short blkoff;
  		seg_i = CURSEG_I(sbi, i);
  		if (sbi->ckpt->alloc_type[i] == SSR)
  			blkoff = sbi->blocks_per_seg;
  		else
  			blkoff = curseg_blkoff(sbi, i);
  
  		for (j = 0; j < blkoff; j++) {
  			if (!page) {
  				page = f2fs_grab_meta_page(sbi, blkaddr++);
  				kaddr = (unsigned char *)page_address(page);
  				memset(kaddr, 0, PAGE_SIZE);
  				written_size = 0;
  			}
  			summary = (struct f2fs_summary *)(kaddr + written_size);
  			*summary = seg_i->sum_blk->entries[j];
  			written_size += SUMMARY_SIZE;
  
  			if (written_size + SUMMARY_SIZE <= PAGE_SIZE -
  							SUM_FOOTER_SIZE)
  				continue;
  
  			set_page_dirty(page);
  			f2fs_put_page(page, 1);
  			page = NULL;
  		}
  	}
  	if (page) {
  		set_page_dirty(page);
  		f2fs_put_page(page, 1);
  	}
  }
  
  static void write_normal_summaries(struct f2fs_sb_info *sbi,
  					block_t blkaddr, int type)
  {
  	int i, end;
  	if (IS_DATASEG(type))
  		end = type + NR_CURSEG_DATA_TYPE;
  	else
  		end = type + NR_CURSEG_NODE_TYPE;
  
  	for (i = type; i < end; i++)
  		write_current_sum_page(sbi, i, blkaddr + (i - type));
  }
  
  void f2fs_write_data_summaries(struct f2fs_sb_info *sbi, block_t start_blk)
  {
  	if (is_set_ckpt_flags(sbi, CP_COMPACT_SUM_FLAG))
  		write_compacted_summaries(sbi, start_blk);
  	else
  		write_normal_summaries(sbi, start_blk, CURSEG_HOT_DATA);
  }
  
  void f2fs_write_node_summaries(struct f2fs_sb_info *sbi, block_t start_blk)
  {
  	write_normal_summaries(sbi, start_blk, CURSEG_HOT_NODE);
  }
  
  int f2fs_lookup_journal_in_cursum(struct f2fs_journal *journal, int type,
  					unsigned int val, int alloc)
  {
  	int i;
  
  	if (type == NAT_JOURNAL) {
  		for (i = 0; i < nats_in_cursum(journal); i++) {
  			if (le32_to_cpu(nid_in_journal(journal, i)) == val)
  				return i;
  		}
  		if (alloc && __has_cursum_space(journal, 1, NAT_JOURNAL))
  			return update_nats_in_cursum(journal, 1);
  	} else if (type == SIT_JOURNAL) {
  		for (i = 0; i < sits_in_cursum(journal); i++)
  			if (le32_to_cpu(segno_in_journal(journal, i)) == val)
  				return i;
  		if (alloc && __has_cursum_space(journal, 1, SIT_JOURNAL))
  			return update_sits_in_cursum(journal, 1);
  	}
  	return -1;
  }
  
  static struct page *get_current_sit_page(struct f2fs_sb_info *sbi,
  					unsigned int segno)
  {
  	return f2fs_get_meta_page_nofail(sbi, current_sit_addr(sbi, segno));
  }
  
  static struct page *get_next_sit_page(struct f2fs_sb_info *sbi,
  					unsigned int start)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	struct page *page;
  	pgoff_t src_off, dst_off;
  
  	src_off = current_sit_addr(sbi, start);
  	dst_off = next_sit_addr(sbi, src_off);
  
  	page = f2fs_grab_meta_page(sbi, dst_off);
  	seg_info_to_sit_page(sbi, page, start);
  
  	set_page_dirty(page);
  	set_to_next_sit(sit_i, start);
  
  	return page;
  }
  
  static struct sit_entry_set *grab_sit_entry_set(void)
  {
  	struct sit_entry_set *ses =
  			f2fs_kmem_cache_alloc(sit_entry_set_slab, GFP_NOFS);
  
  	ses->entry_cnt = 0;
  	INIT_LIST_HEAD(&ses->set_list);
  	return ses;
  }
  
  static void release_sit_entry_set(struct sit_entry_set *ses)
  {
  	list_del(&ses->set_list);
  	kmem_cache_free(sit_entry_set_slab, ses);
  }
  
  static void adjust_sit_entry_set(struct sit_entry_set *ses,
  						struct list_head *head)
  {
  	struct sit_entry_set *next = ses;
  
  	if (list_is_last(&ses->set_list, head))
  		return;
  
  	list_for_each_entry_continue(next, head, set_list)
  		if (ses->entry_cnt <= next->entry_cnt)
  			break;
  
  	list_move_tail(&ses->set_list, &next->set_list);
  }
  
  static void add_sit_entry(unsigned int segno, struct list_head *head)
  {
  	struct sit_entry_set *ses;
  	unsigned int start_segno = START_SEGNO(segno);
  
  	list_for_each_entry(ses, head, set_list) {
  		if (ses->start_segno == start_segno) {
  			ses->entry_cnt++;
  			adjust_sit_entry_set(ses, head);
  			return;
  		}
  	}
  
  	ses = grab_sit_entry_set();
  
  	ses->start_segno = start_segno;
  	ses->entry_cnt++;
  	list_add(&ses->set_list, head);
  }
  
  static void add_sits_in_set(struct f2fs_sb_info *sbi)
  {
  	struct f2fs_sm_info *sm_info = SM_I(sbi);
  	struct list_head *set_list = &sm_info->sit_entry_set;
  	unsigned long *bitmap = SIT_I(sbi)->dirty_sentries_bitmap;
  	unsigned int segno;
  
  	for_each_set_bit(segno, bitmap, MAIN_SEGS(sbi))
  		add_sit_entry(segno, set_list);
  }
  
  static void remove_sits_in_journal(struct f2fs_sb_info *sbi)
  {
  	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
  	struct f2fs_journal *journal = curseg->journal;
  	int i;
  
  	down_write(&curseg->journal_rwsem);
  	for (i = 0; i < sits_in_cursum(journal); i++) {
  		unsigned int segno;
  		bool dirtied;
  
  		segno = le32_to_cpu(segno_in_journal(journal, i));
  		dirtied = __mark_sit_entry_dirty(sbi, segno);
  
  		if (!dirtied)
  			add_sit_entry(segno, &SM_I(sbi)->sit_entry_set);
  	}
  	update_sits_in_cursum(journal, -i);
  	up_write(&curseg->journal_rwsem);
  }
  
  /*
   * CP calls this function, which flushes SIT entries including sit_journal,
   * and moves prefree segs to free segs.
   */
  void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	unsigned long *bitmap = sit_i->dirty_sentries_bitmap;
  	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
  	struct f2fs_journal *journal = curseg->journal;
  	struct sit_entry_set *ses, *tmp;
  	struct list_head *head = &SM_I(sbi)->sit_entry_set;
  	bool to_journal = !is_sbi_flag_set(sbi, SBI_IS_RESIZEFS);
  	struct seg_entry *se;
  
  	down_write(&sit_i->sentry_lock);
  
  	if (!sit_i->dirty_sentries)
  		goto out;
  
  	/*
  	 * add and account sit entries of dirty bitmap in sit entry
  	 * set temporarily
  	 */
  	add_sits_in_set(sbi);
  
  	/*
  	 * if there are no enough space in journal to store dirty sit
  	 * entries, remove all entries from journal and add and account
  	 * them in sit entry set.
  	 */
  	if (!__has_cursum_space(journal, sit_i->dirty_sentries, SIT_JOURNAL) ||
  								!to_journal)
  		remove_sits_in_journal(sbi);
  
  	/*
  	 * there are two steps to flush sit entries:
  	 * #1, flush sit entries to journal in current cold data summary block.
  	 * #2, flush sit entries to sit page.
  	 */
  	list_for_each_entry_safe(ses, tmp, head, set_list) {
  		struct page *page = NULL;
  		struct f2fs_sit_block *raw_sit = NULL;
  		unsigned int start_segno = ses->start_segno;
  		unsigned int end = min(start_segno + SIT_ENTRY_PER_BLOCK,
  						(unsigned long)MAIN_SEGS(sbi));
  		unsigned int segno = start_segno;
  
  		if (to_journal &&
  			!__has_cursum_space(journal, ses->entry_cnt, SIT_JOURNAL))
  			to_journal = false;
  
  		if (to_journal) {
  			down_write(&curseg->journal_rwsem);
  		} else {
  			page = get_next_sit_page(sbi, start_segno);
  			raw_sit = page_address(page);
  		}
  
  		/* flush dirty sit entries in region of current sit set */
  		for_each_set_bit_from(segno, bitmap, end) {
  			int offset, sit_offset;
  
  			se = get_seg_entry(sbi, segno);
  #ifdef CONFIG_F2FS_CHECK_FS
  			if (memcmp(se->cur_valid_map, se->cur_valid_map_mir,
  						SIT_VBLOCK_MAP_SIZE))
  				f2fs_bug_on(sbi, 1);
  #endif
  
  			/* add discard candidates */
  			if (!(cpc->reason & CP_DISCARD)) {
  				cpc->trim_start = segno;
  				add_discard_addrs(sbi, cpc, false);
  			}
  
  			if (to_journal) {
  				offset = f2fs_lookup_journal_in_cursum(journal,
  							SIT_JOURNAL, segno, 1);
  				f2fs_bug_on(sbi, offset < 0);
  				segno_in_journal(journal, offset) =
  							cpu_to_le32(segno);
  				seg_info_to_raw_sit(se,
  					&sit_in_journal(journal, offset));
  				check_block_count(sbi, segno,
  					&sit_in_journal(journal, offset));
  			} else {
  				sit_offset = SIT_ENTRY_OFFSET(sit_i, segno);
  				seg_info_to_raw_sit(se,
  						&raw_sit->entries[sit_offset]);
  				check_block_count(sbi, segno,
  						&raw_sit->entries[sit_offset]);
  			}
  
  			__clear_bit(segno, bitmap);
  			sit_i->dirty_sentries--;
  			ses->entry_cnt--;
  		}
  
  		if (to_journal)
  			up_write(&curseg->journal_rwsem);
  		else
  			f2fs_put_page(page, 1);
  
  		f2fs_bug_on(sbi, ses->entry_cnt);
  		release_sit_entry_set(ses);
  	}
  
  	f2fs_bug_on(sbi, !list_empty(head));
  	f2fs_bug_on(sbi, sit_i->dirty_sentries);
  out:
  	if (cpc->reason & CP_DISCARD) {
  		__u64 trim_start = cpc->trim_start;
  
  		for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++)
  			add_discard_addrs(sbi, cpc, false);
  
  		cpc->trim_start = trim_start;
  	}
  	up_write(&sit_i->sentry_lock);
  
  	set_prefree_as_free_segments(sbi);
  }
  
  static int build_sit_info(struct f2fs_sb_info *sbi)
  {
  	struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
  	struct sit_info *sit_i;
  	unsigned int sit_segs, start;
  	char *src_bitmap, *bitmap;
  	unsigned int bitmap_size, main_bitmap_size, sit_bitmap_size;
  
  	/* allocate memory for SIT information */
  	sit_i = f2fs_kzalloc(sbi, sizeof(struct sit_info), GFP_KERNEL);
  	if (!sit_i)
  		return -ENOMEM;
  
  	SM_I(sbi)->sit_info = sit_i;
  
  	sit_i->sentries =
  		f2fs_kvzalloc(sbi, array_size(sizeof(struct seg_entry),
  					      MAIN_SEGS(sbi)),
  			      GFP_KERNEL);
  	if (!sit_i->sentries)
  		return -ENOMEM;
  
  	main_bitmap_size = f2fs_bitmap_size(MAIN_SEGS(sbi));
  	sit_i->dirty_sentries_bitmap = f2fs_kvzalloc(sbi, main_bitmap_size,
  								GFP_KERNEL);
  	if (!sit_i->dirty_sentries_bitmap)
  		return -ENOMEM;
  
  #ifdef CONFIG_F2FS_CHECK_FS
  	bitmap_size = MAIN_SEGS(sbi) * SIT_VBLOCK_MAP_SIZE * 4;
  #else
  	bitmap_size = MAIN_SEGS(sbi) * SIT_VBLOCK_MAP_SIZE * 3;
  #endif
  	sit_i->bitmap = f2fs_kvzalloc(sbi, bitmap_size, GFP_KERNEL);
  	if (!sit_i->bitmap)
  		return -ENOMEM;
  
  	bitmap = sit_i->bitmap;
  
  	for (start = 0; start < MAIN_SEGS(sbi); start++) {
  		sit_i->sentries[start].cur_valid_map = bitmap;
  		bitmap += SIT_VBLOCK_MAP_SIZE;
  
  		sit_i->sentries[start].ckpt_valid_map = bitmap;
  		bitmap += SIT_VBLOCK_MAP_SIZE;
  
  #ifdef CONFIG_F2FS_CHECK_FS
  		sit_i->sentries[start].cur_valid_map_mir = bitmap;
  		bitmap += SIT_VBLOCK_MAP_SIZE;
  #endif
  
  		sit_i->sentries[start].discard_map = bitmap;
  		bitmap += SIT_VBLOCK_MAP_SIZE;
  	}
  
  	sit_i->tmp_map = f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
  	if (!sit_i->tmp_map)
  		return -ENOMEM;
  
  	if (__is_large_section(sbi)) {
  		sit_i->sec_entries =
  			f2fs_kvzalloc(sbi, array_size(sizeof(struct sec_entry),
  						      MAIN_SECS(sbi)),
  				      GFP_KERNEL);
  		if (!sit_i->sec_entries)
  			return -ENOMEM;
  	}
  
  	/* get information related with SIT */
  	sit_segs = le32_to_cpu(raw_super->segment_count_sit) >> 1;
  
  	/* setup SIT bitmap from ckeckpoint pack */
  	sit_bitmap_size = __bitmap_size(sbi, SIT_BITMAP);
  	src_bitmap = __bitmap_ptr(sbi, SIT_BITMAP);
  
  	sit_i->sit_bitmap = kmemdup(src_bitmap, sit_bitmap_size, GFP_KERNEL);
  	if (!sit_i->sit_bitmap)
  		return -ENOMEM;
  
  #ifdef CONFIG_F2FS_CHECK_FS
  	sit_i->sit_bitmap_mir = kmemdup(src_bitmap,
  					sit_bitmap_size, GFP_KERNEL);
  	if (!sit_i->sit_bitmap_mir)
  		return -ENOMEM;
  
  	sit_i->invalid_segmap = f2fs_kvzalloc(sbi,
  					main_bitmap_size, GFP_KERNEL);
  	if (!sit_i->invalid_segmap)
  		return -ENOMEM;
  #endif
  
  	/* init SIT information */
  	sit_i->s_ops = &default_salloc_ops;
  
  	sit_i->sit_base_addr = le32_to_cpu(raw_super->sit_blkaddr);
  	sit_i->sit_blocks = sit_segs << sbi->log_blocks_per_seg;
  	sit_i->written_valid_blocks = 0;
  	sit_i->bitmap_size = sit_bitmap_size;
  	sit_i->dirty_sentries = 0;
  	sit_i->sents_per_block = SIT_ENTRY_PER_BLOCK;
  	sit_i->elapsed_time = le64_to_cpu(sbi->ckpt->elapsed_time);
  	sit_i->mounted_time = ktime_get_boottime_seconds();
  	init_rwsem(&sit_i->sentry_lock);
  	return 0;
  }
  
  static int build_free_segmap(struct f2fs_sb_info *sbi)
  {
  	struct free_segmap_info *free_i;
  	unsigned int bitmap_size, sec_bitmap_size;
  
  	/* allocate memory for free segmap information */
  	free_i = f2fs_kzalloc(sbi, sizeof(struct free_segmap_info), GFP_KERNEL);
  	if (!free_i)
  		return -ENOMEM;
  
  	SM_I(sbi)->free_info = free_i;
  
  	bitmap_size = f2fs_bitmap_size(MAIN_SEGS(sbi));
  	free_i->free_segmap = f2fs_kvmalloc(sbi, bitmap_size, GFP_KERNEL);
  	if (!free_i->free_segmap)
  		return -ENOMEM;
  
  	sec_bitmap_size = f2fs_bitmap_size(MAIN_SECS(sbi));
  	free_i->free_secmap = f2fs_kvmalloc(sbi, sec_bitmap_size, GFP_KERNEL);
  	if (!free_i->free_secmap)
  		return -ENOMEM;
  
  	/* set all segments as dirty temporarily */
  	memset(free_i->free_segmap, 0xff, bitmap_size);
  	memset(free_i->free_secmap, 0xff, sec_bitmap_size);
  
  	/* init free segmap information */
  	free_i->start_segno = GET_SEGNO_FROM_SEG0(sbi, MAIN_BLKADDR(sbi));
  	free_i->free_segments = 0;
  	free_i->free_sections = 0;
  	spin_lock_init(&free_i->segmap_lock);
  	return 0;
  }
  
  static int build_curseg(struct f2fs_sb_info *sbi)
  {
  	struct curseg_info *array;
  	int i;
  
  	array = f2fs_kzalloc(sbi, array_size(NR_CURSEG_TYPE, sizeof(*array)),
  			     GFP_KERNEL);
  	if (!array)
  		return -ENOMEM;
  
  	SM_I(sbi)->curseg_array = array;
  
  	for (i = 0; i < NR_CURSEG_TYPE; i++) {
  		mutex_init(&array[i].curseg_mutex);
  		array[i].sum_blk = f2fs_kzalloc(sbi, PAGE_SIZE, GFP_KERNEL);
  		if (!array[i].sum_blk)
  			return -ENOMEM;
  		init_rwsem(&array[i].journal_rwsem);
  		array[i].journal = f2fs_kzalloc(sbi,
  				sizeof(struct f2fs_journal), GFP_KERNEL);
  		if (!array[i].journal)
  			return -ENOMEM;
  		array[i].segno = NULL_SEGNO;
  		array[i].next_blkoff = 0;
  	}
  	return restore_curseg_summaries(sbi);
  }
  
  static int build_sit_entries(struct f2fs_sb_info *sbi)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
  	struct f2fs_journal *journal = curseg->journal;
  	struct seg_entry *se;
  	struct f2fs_sit_entry sit;
  	int sit_blk_cnt = SIT_BLK_CNT(sbi);
  	unsigned int i, start, end;
  	unsigned int readed, start_blk = 0;
  	int err = 0;
  	block_t total_node_blocks = 0;
  
  	do {
  		readed = f2fs_ra_meta_pages(sbi, start_blk, BIO_MAX_PAGES,
  							META_SIT, true);
  
  		start = start_blk * sit_i->sents_per_block;
  		end = (start_blk + readed) * sit_i->sents_per_block;
  
  		for (; start < end && start < MAIN_SEGS(sbi); start++) {
  			struct f2fs_sit_block *sit_blk;
  			struct page *page;
  
  			se = &sit_i->sentries[start];
  			page = get_current_sit_page(sbi, start);
  			if (IS_ERR(page))
  				return PTR_ERR(page);
  			sit_blk = (struct f2fs_sit_block *)page_address(page);
  			sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
  			f2fs_put_page(page, 1);
  
  			err = check_block_count(sbi, start, &sit);
  			if (err)
  				return err;
  			seg_info_from_raw_sit(se, &sit);
  			if (IS_NODESEG(se->type))
  				total_node_blocks += se->valid_blocks;
  
  			/* build discard map only one time */
  			if (is_set_ckpt_flags(sbi, CP_TRIMMED_FLAG)) {
  				memset(se->discard_map, 0xff,
  					SIT_VBLOCK_MAP_SIZE);
  			} else {
  				memcpy(se->discard_map,
  					se->cur_valid_map,
  					SIT_VBLOCK_MAP_SIZE);
  				sbi->discard_blks +=
  					sbi->blocks_per_seg -
  					se->valid_blocks;
  			}
  
  			if (__is_large_section(sbi))
  				get_sec_entry(sbi, start)->valid_blocks +=
  							se->valid_blocks;
  		}
  		start_blk += readed;
  	} while (start_blk < sit_blk_cnt);
  
  	down_read(&curseg->journal_rwsem);
  	for (i = 0; i < sits_in_cursum(journal); i++) {
  		unsigned int old_valid_blocks;
  
  		start = le32_to_cpu(segno_in_journal(journal, i));
  		if (start >= MAIN_SEGS(sbi)) {
  			f2fs_err(sbi, "Wrong journal entry on segno %u",
  				 start);
  			err = -EFSCORRUPTED;
  			break;
  		}
  
  		se = &sit_i->sentries[start];
  		sit = sit_in_journal(journal, i);
  
  		old_valid_blocks = se->valid_blocks;
  		if (IS_NODESEG(se->type))
  			total_node_blocks -= old_valid_blocks;
  
  		err = check_block_count(sbi, start, &sit);
  		if (err)
  			break;
  		seg_info_from_raw_sit(se, &sit);
  		if (IS_NODESEG(se->type))
  			total_node_blocks += se->valid_blocks;
  
  		if (is_set_ckpt_flags(sbi, CP_TRIMMED_FLAG)) {
  			memset(se->discard_map, 0xff, SIT_VBLOCK_MAP_SIZE);
  		} else {
  			memcpy(se->discard_map, se->cur_valid_map,
  						SIT_VBLOCK_MAP_SIZE);
  			sbi->discard_blks += old_valid_blocks;
  			sbi->discard_blks -= se->valid_blocks;
  		}
  
  		if (__is_large_section(sbi)) {
  			get_sec_entry(sbi, start)->valid_blocks +=
  							se->valid_blocks;
  			get_sec_entry(sbi, start)->valid_blocks -=
  							old_valid_blocks;
  		}
  	}
  	up_read(&curseg->journal_rwsem);
  
  	if (!err && total_node_blocks != valid_node_count(sbi)) {
  		f2fs_err(sbi, "SIT is corrupted node# %u vs %u",
  			 total_node_blocks, valid_node_count(sbi));
  		err = -EFSCORRUPTED;
  	}
  
  	return err;
  }
  
  static void init_free_segmap(struct f2fs_sb_info *sbi)
  {
  	unsigned int start;
  	int type;
  
  	for (start = 0; start < MAIN_SEGS(sbi); start++) {
  		struct seg_entry *sentry = get_seg_entry(sbi, start);
  		if (!sentry->valid_blocks)
  			__set_free(sbi, start);
  		else
  			SIT_I(sbi)->written_valid_blocks +=
  						sentry->valid_blocks;
  	}
  
  	/* set use the current segments */
  	for (type = CURSEG_HOT_DATA; type <= CURSEG_COLD_NODE; type++) {
  		struct curseg_info *curseg_t = CURSEG_I(sbi, type);
  		__set_test_and_inuse(sbi, curseg_t->segno);
  	}
  }
  
  static void init_dirty_segmap(struct f2fs_sb_info *sbi)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  	struct free_segmap_info *free_i = FREE_I(sbi);
  	unsigned int segno = 0, offset = 0;
  	unsigned short valid_blocks;
  
  	while (1) {
  		/* find dirty segment based on free segmap */
  		segno = find_next_inuse(free_i, MAIN_SEGS(sbi), offset);
  		if (segno >= MAIN_SEGS(sbi))
  			break;
  		offset = segno + 1;
  		valid_blocks = get_valid_blocks(sbi, segno, false);
  		if (valid_blocks == sbi->blocks_per_seg || !valid_blocks)
  			continue;
  		if (valid_blocks > sbi->blocks_per_seg) {
  			f2fs_bug_on(sbi, 1);
  			continue;
  		}
  		mutex_lock(&dirty_i->seglist_lock);
  		__locate_dirty_segment(sbi, segno, DIRTY);
  		mutex_unlock(&dirty_i->seglist_lock);
  	}
  }
  
  static int init_victim_secmap(struct f2fs_sb_info *sbi)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  	unsigned int bitmap_size = f2fs_bitmap_size(MAIN_SECS(sbi));
  
  	dirty_i->victim_secmap = f2fs_kvzalloc(sbi, bitmap_size, GFP_KERNEL);
  	if (!dirty_i->victim_secmap)
  		return -ENOMEM;
  	return 0;
  }
  
  static int build_dirty_segmap(struct f2fs_sb_info *sbi)
  {
  	struct dirty_seglist_info *dirty_i;
  	unsigned int bitmap_size, i;
  
  	/* allocate memory for dirty segments list information */
  	dirty_i = f2fs_kzalloc(sbi, sizeof(struct dirty_seglist_info),
  								GFP_KERNEL);
  	if (!dirty_i)
  		return -ENOMEM;
  
  	SM_I(sbi)->dirty_info = dirty_i;
  	mutex_init(&dirty_i->seglist_lock);
  
  	bitmap_size = f2fs_bitmap_size(MAIN_SEGS(sbi));
  
  	for (i = 0; i < NR_DIRTY_TYPE; i++) {
  		dirty_i->dirty_segmap[i] = f2fs_kvzalloc(sbi, bitmap_size,
  								GFP_KERNEL);
  		if (!dirty_i->dirty_segmap[i])
  			return -ENOMEM;
  	}
  
  	init_dirty_segmap(sbi);
  	return init_victim_secmap(sbi);
  }
  
  static int sanity_check_curseg(struct f2fs_sb_info *sbi)
  {
  	int i;
  
  	/*
  	 * In LFS/SSR curseg, .next_blkoff should point to an unused blkaddr;
  	 * In LFS curseg, all blkaddr after .next_blkoff should be unused.
  	 */
  	for (i = 0; i < NO_CHECK_TYPE; i++) {
  		struct curseg_info *curseg = CURSEG_I(sbi, i);
  		struct seg_entry *se = get_seg_entry(sbi, curseg->segno);
  		unsigned int blkofs = curseg->next_blkoff;
  
  		if (f2fs_test_bit(blkofs, se->cur_valid_map))
  			goto out;
  
  		if (curseg->alloc_type == SSR)
  			continue;
  
  		for (blkofs += 1; blkofs < sbi->blocks_per_seg; blkofs++) {
  			if (!f2fs_test_bit(blkofs, se->cur_valid_map))
  				continue;
  out:
  			f2fs_err(sbi,
  				 "Current segment's next free block offset is inconsistent with bitmap, logtype:%u, segno:%u, type:%u, next_blkoff:%u, blkofs:%u",
  				 i, curseg->segno, curseg->alloc_type,
  				 curseg->next_blkoff, blkofs);
  			return -EFSCORRUPTED;
  		}
  	}
  	return 0;
  }
  
  #ifdef CONFIG_BLK_DEV_ZONED
  
  static int check_zone_write_pointer(struct f2fs_sb_info *sbi,
  				    struct f2fs_dev_info *fdev,
  				    struct blk_zone *zone)
  {
  	unsigned int wp_segno, wp_blkoff, zone_secno, zone_segno, segno;
  	block_t zone_block, wp_block, last_valid_block;
  	unsigned int log_sectors_per_block = sbi->log_blocksize - SECTOR_SHIFT;
  	int i, s, b, ret;
  	struct seg_entry *se;
  
  	if (zone->type != BLK_ZONE_TYPE_SEQWRITE_REQ)
  		return 0;
  
  	wp_block = fdev->start_blk + (zone->wp >> log_sectors_per_block);
  	wp_segno = GET_SEGNO(sbi, wp_block);
  	wp_blkoff = wp_block - START_BLOCK(sbi, wp_segno);
  	zone_block = fdev->start_blk + (zone->start >> log_sectors_per_block);
  	zone_segno = GET_SEGNO(sbi, zone_block);
  	zone_secno = GET_SEC_FROM_SEG(sbi, zone_segno);
  
  	if (zone_segno >= MAIN_SEGS(sbi))
  		return 0;
  
  	/*
  	 * Skip check of zones cursegs point to, since
  	 * fix_curseg_write_pointer() checks them.
  	 */
  	for (i = 0; i < NO_CHECK_TYPE; i++)
  		if (zone_secno == GET_SEC_FROM_SEG(sbi,
  						   CURSEG_I(sbi, i)->segno))
  			return 0;
  
  	/*
  	 * Get last valid block of the zone.
  	 */
  	last_valid_block = zone_block - 1;
  	for (s = sbi->segs_per_sec - 1; s >= 0; s--) {
  		segno = zone_segno + s;
  		se = get_seg_entry(sbi, segno);
  		for (b = sbi->blocks_per_seg - 1; b >= 0; b--)
  			if (f2fs_test_bit(b, se->cur_valid_map)) {
  				last_valid_block = START_BLOCK(sbi, segno) + b;
  				break;
  			}
  		if (last_valid_block >= zone_block)
  			break;
  	}
  
  	/*
  	 * If last valid block is beyond the write pointer, report the
  	 * inconsistency. This inconsistency does not cause write error
  	 * because the zone will not be selected for write operation until
  	 * it get discarded. Just report it.
  	 */
  	if (last_valid_block >= wp_block) {
  		f2fs_notice(sbi, "Valid block beyond write pointer: "
  			    "valid block[0x%x,0x%x] wp[0x%x,0x%x]",
  			    GET_SEGNO(sbi, last_valid_block),
  			    GET_BLKOFF_FROM_SEG0(sbi, last_valid_block),
  			    wp_segno, wp_blkoff);
  		return 0;
  	}
  
  	/*
  	 * If there is no valid block in the zone and if write pointer is
  	 * not at zone start, reset the write pointer.
  	 */
  	if (last_valid_block + 1 == zone_block && zone->wp != zone->start) {
  		f2fs_notice(sbi,
  			    "Zone without valid block has non-zero write "
  			    "pointer. Reset the write pointer: wp[0x%x,0x%x]",
  			    wp_segno, wp_blkoff);
  		ret = __f2fs_issue_discard_zone(sbi, fdev->bdev, zone_block,
  					zone->len >> log_sectors_per_block);
  		if (ret) {
  			f2fs_err(sbi, "Discard zone failed: %s (errno=%d)",
  				 fdev->path, ret);
  			return ret;
  		}
  	}
  
  	return 0;
  }
  
  static struct f2fs_dev_info *get_target_zoned_dev(struct f2fs_sb_info *sbi,
  						  block_t zone_blkaddr)
  {
  	int i;
  
  	for (i = 0; i < sbi->s_ndevs; i++) {
  		if (!bdev_is_zoned(FDEV(i).bdev))
  			continue;
  		if (sbi->s_ndevs == 1 || (FDEV(i).start_blk <= zone_blkaddr &&
  				zone_blkaddr <= FDEV(i).end_blk))
  			return &FDEV(i);
  	}
  
  	return NULL;
  }
  
  static int report_one_zone_cb(struct blk_zone *zone, unsigned int idx,
  			      void *data) {
  	memcpy(data, zone, sizeof(struct blk_zone));
  	return 0;
  }
  
  static int fix_curseg_write_pointer(struct f2fs_sb_info *sbi, int type)
  {
  	struct curseg_info *cs = CURSEG_I(sbi, type);
  	struct f2fs_dev_info *zbd;
  	struct blk_zone zone;
  	unsigned int cs_section, wp_segno, wp_blkoff, wp_sector_off;
  	block_t cs_zone_block, wp_block;
  	unsigned int log_sectors_per_block = sbi->log_blocksize - SECTOR_SHIFT;
  	sector_t zone_sector;
  	int err;
  
  	cs_section = GET_SEC_FROM_SEG(sbi, cs->segno);
  	cs_zone_block = START_BLOCK(sbi, GET_SEG_FROM_SEC(sbi, cs_section));
  
  	zbd = get_target_zoned_dev(sbi, cs_zone_block);
  	if (!zbd)
  		return 0;
  
  	/* report zone for the sector the curseg points to */
  	zone_sector = (sector_t)(cs_zone_block - zbd->start_blk)
  		<< log_sectors_per_block;
  	err = blkdev_report_zones(zbd->bdev, zone_sector, 1,
  				  report_one_zone_cb, &zone);
  	if (err != 1) {
  		f2fs_err(sbi, "Report zone failed: %s errno=(%d)",
  			 zbd->path, err);
  		return err;
  	}
  
  	if (zone.type != BLK_ZONE_TYPE_SEQWRITE_REQ)
  		return 0;
  
  	wp_block = zbd->start_blk + (zone.wp >> log_sectors_per_block);
  	wp_segno = GET_SEGNO(sbi, wp_block);
  	wp_blkoff = wp_block - START_BLOCK(sbi, wp_segno);
  	wp_sector_off = zone.wp & GENMASK(log_sectors_per_block - 1, 0);
  
  	if (cs->segno == wp_segno && cs->next_blkoff == wp_blkoff &&
  		wp_sector_off == 0)
  		return 0;
  
  	f2fs_notice(sbi, "Unaligned curseg[%d] with write pointer: "
  		    "curseg[0x%x,0x%x] wp[0x%x,0x%x]",
  		    type, cs->segno, cs->next_blkoff, wp_segno, wp_blkoff);
  
  	f2fs_notice(sbi, "Assign new section to curseg[%d]: "
  		    "curseg[0x%x,0x%x]", type, cs->segno, cs->next_blkoff);
  	allocate_segment_by_default(sbi, type, true);
  
  	/* check consistency of the zone curseg pointed to */
  	if (check_zone_write_pointer(sbi, zbd, &zone))
  		return -EIO;
  
  	/* check newly assigned zone */
  	cs_section = GET_SEC_FROM_SEG(sbi, cs->segno);
  	cs_zone_block = START_BLOCK(sbi, GET_SEG_FROM_SEC(sbi, cs_section));
  
  	zbd = get_target_zoned_dev(sbi, cs_zone_block);
  	if (!zbd)
  		return 0;
  
  	zone_sector = (sector_t)(cs_zone_block - zbd->start_blk)
  		<< log_sectors_per_block;
  	err = blkdev_report_zones(zbd->bdev, zone_sector, 1,
  				  report_one_zone_cb, &zone);
  	if (err != 1) {
  		f2fs_err(sbi, "Report zone failed: %s errno=(%d)",
  			 zbd->path, err);
  		return err;
  	}
  
  	if (zone.type != BLK_ZONE_TYPE_SEQWRITE_REQ)
  		return 0;
  
  	if (zone.wp != zone.start) {
  		f2fs_notice(sbi,
  			    "New zone for curseg[%d] is not yet discarded. "
  			    "Reset the zone: curseg[0x%x,0x%x]",
  			    type, cs->segno, cs->next_blkoff);
  		err = __f2fs_issue_discard_zone(sbi, zbd->bdev,
  				zone_sector >> log_sectors_per_block,
  				zone.len >> log_sectors_per_block);
  		if (err) {
  			f2fs_err(sbi, "Discard zone failed: %s (errno=%d)",
  				 zbd->path, err);
  			return err;
  		}
  	}
  
  	return 0;
  }
  
  int f2fs_fix_curseg_write_pointer(struct f2fs_sb_info *sbi)
  {
  	int i, ret;
  
  	for (i = 0; i < NO_CHECK_TYPE; i++) {
  		ret = fix_curseg_write_pointer(sbi, i);
  		if (ret)
  			return ret;
  	}
  
  	return 0;
  }
  
  struct check_zone_write_pointer_args {
  	struct f2fs_sb_info *sbi;
  	struct f2fs_dev_info *fdev;
  };
  
  static int check_zone_write_pointer_cb(struct blk_zone *zone, unsigned int idx,
  				      void *data) {
  	struct check_zone_write_pointer_args *args;
  	args = (struct check_zone_write_pointer_args *)data;
  
  	return check_zone_write_pointer(args->sbi, args->fdev, zone);
  }
  
  int f2fs_check_write_pointer(struct f2fs_sb_info *sbi)
  {
  	int i, ret;
  	struct check_zone_write_pointer_args args;
  
  	for (i = 0; i < sbi->s_ndevs; i++) {
  		if (!bdev_is_zoned(FDEV(i).bdev))
  			continue;
  
  		args.sbi = sbi;
  		args.fdev = &FDEV(i);
  		ret = blkdev_report_zones(FDEV(i).bdev, 0, BLK_ALL_ZONES,
  					  check_zone_write_pointer_cb, &args);
  		if (ret < 0)
  			return ret;
  	}
  
  	return 0;
  }
  #else
  int f2fs_fix_curseg_write_pointer(struct f2fs_sb_info *sbi)
  {
  	return 0;
  }
  
  int f2fs_check_write_pointer(struct f2fs_sb_info *sbi)
  {
  	return 0;
  }
  #endif
  
  /*
   * Update min, max modified time for cost-benefit GC algorithm
   */
  static void init_min_max_mtime(struct f2fs_sb_info *sbi)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  	unsigned int segno;
  
  	down_write(&sit_i->sentry_lock);
  
  	sit_i->min_mtime = ULLONG_MAX;
  
  	for (segno = 0; segno < MAIN_SEGS(sbi); segno += sbi->segs_per_sec) {
  		unsigned int i;
  		unsigned long long mtime = 0;
  
  		for (i = 0; i < sbi->segs_per_sec; i++)
  			mtime += get_seg_entry(sbi, segno + i)->mtime;
  
  		mtime = div_u64(mtime, sbi->segs_per_sec);
  
  		if (sit_i->min_mtime > mtime)
  			sit_i->min_mtime = mtime;
  	}
  	sit_i->max_mtime = get_mtime(sbi, false);
  	up_write(&sit_i->sentry_lock);
  }
  
  int f2fs_build_segment_manager(struct f2fs_sb_info *sbi)
  {
  	struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
  	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
  	struct f2fs_sm_info *sm_info;
  	int err;
  
  	sm_info = f2fs_kzalloc(sbi, sizeof(struct f2fs_sm_info), GFP_KERNEL);
  	if (!sm_info)
  		return -ENOMEM;
  
  	/* init sm info */
  	sbi->sm_info = sm_info;
  	sm_info->seg0_blkaddr = le32_to_cpu(raw_super->segment0_blkaddr);
  	sm_info->main_blkaddr = le32_to_cpu(raw_super->main_blkaddr);
  	sm_info->segment_count = le32_to_cpu(raw_super->segment_count);
  	sm_info->reserved_segments = le32_to_cpu(ckpt->rsvd_segment_count);
  	sm_info->ovp_segments = le32_to_cpu(ckpt->overprov_segment_count);
  	sm_info->main_segments = le32_to_cpu(raw_super->segment_count_main);
  	sm_info->ssa_blkaddr = le32_to_cpu(raw_super->ssa_blkaddr);
  	sm_info->rec_prefree_segments = sm_info->main_segments *
  					DEF_RECLAIM_PREFREE_SEGMENTS / 100;
  	if (sm_info->rec_prefree_segments > DEF_MAX_RECLAIM_PREFREE_SEGMENTS)
  		sm_info->rec_prefree_segments = DEF_MAX_RECLAIM_PREFREE_SEGMENTS;
  
  	if (!f2fs_lfs_mode(sbi))
  		sm_info->ipu_policy = 1 << F2FS_IPU_FSYNC;
  	sm_info->min_ipu_util = DEF_MIN_IPU_UTIL;
  	sm_info->min_fsync_blocks = DEF_MIN_FSYNC_BLOCKS;
  	sm_info->min_seq_blocks = sbi->blocks_per_seg * sbi->segs_per_sec;
  	sm_info->min_hot_blocks = DEF_MIN_HOT_BLOCKS;
  	sm_info->min_ssr_sections = reserved_sections(sbi);
  
  	INIT_LIST_HEAD(&sm_info->sit_entry_set);
  
  	init_rwsem(&sm_info->curseg_lock);
  
  	if (!f2fs_readonly(sbi->sb)) {
  		err = f2fs_create_flush_cmd_control(sbi);
  		if (err)
  			return err;
  	}
  
  	err = create_discard_cmd_control(sbi);
  	if (err)
  		return err;
  
  	err = build_sit_info(sbi);
  	if (err)
  		return err;
  	err = build_free_segmap(sbi);
  	if (err)
  		return err;
  	err = build_curseg(sbi);
  	if (err)
  		return err;
  
  	/* reinit free segmap based on SIT */
  	err = build_sit_entries(sbi);
  	if (err)
  		return err;
  
  	init_free_segmap(sbi);
  	err = build_dirty_segmap(sbi);
  	if (err)
  		return err;
  
  	err = sanity_check_curseg(sbi);
  	if (err)
  		return err;
  
  	init_min_max_mtime(sbi);
  	return 0;
  }
  
  static void discard_dirty_segmap(struct f2fs_sb_info *sbi,
  		enum dirty_type dirty_type)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  
  	mutex_lock(&dirty_i->seglist_lock);
  	kvfree(dirty_i->dirty_segmap[dirty_type]);
  	dirty_i->nr_dirty[dirty_type] = 0;
  	mutex_unlock(&dirty_i->seglist_lock);
  }
  
  static void destroy_victim_secmap(struct f2fs_sb_info *sbi)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  	kvfree(dirty_i->victim_secmap);
  }
  
  static void destroy_dirty_segmap(struct f2fs_sb_info *sbi)
  {
  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
  	int i;
  
  	if (!dirty_i)
  		return;
  
  	/* discard pre-free/dirty segments list */
  	for (i = 0; i < NR_DIRTY_TYPE; i++)
  		discard_dirty_segmap(sbi, i);
  
  	destroy_victim_secmap(sbi);
  	SM_I(sbi)->dirty_info = NULL;
  	kvfree(dirty_i);
  }
  
  static void destroy_curseg(struct f2fs_sb_info *sbi)
  {
  	struct curseg_info *array = SM_I(sbi)->curseg_array;
  	int i;
  
  	if (!array)
  		return;
  	SM_I(sbi)->curseg_array = NULL;
  	for (i = 0; i < NR_CURSEG_TYPE; i++) {
  		kvfree(array[i].sum_blk);
  		kvfree(array[i].journal);
  	}
  	kvfree(array);
  }
  
  static void destroy_free_segmap(struct f2fs_sb_info *sbi)
  {
  	struct free_segmap_info *free_i = SM_I(sbi)->free_info;
  	if (!free_i)
  		return;
  	SM_I(sbi)->free_info = NULL;
  	kvfree(free_i->free_segmap);
  	kvfree(free_i->free_secmap);
  	kvfree(free_i);
  }
  
  static void destroy_sit_info(struct f2fs_sb_info *sbi)
  {
  	struct sit_info *sit_i = SIT_I(sbi);
  
  	if (!sit_i)
  		return;
  
  	if (sit_i->sentries)
  		kvfree(sit_i->bitmap);
  	kvfree(sit_i->tmp_map);
  
  	kvfree(sit_i->sentries);
  	kvfree(sit_i->sec_entries);
  	kvfree(sit_i->dirty_sentries_bitmap);
  
  	SM_I(sbi)->sit_info = NULL;
  	kvfree(sit_i->sit_bitmap);
  #ifdef CONFIG_F2FS_CHECK_FS
  	kvfree(sit_i->sit_bitmap_mir);
  	kvfree(sit_i->invalid_segmap);
  #endif
  	kvfree(sit_i);
  }
  
  void f2fs_destroy_segment_manager(struct f2fs_sb_info *sbi)
  {
  	struct f2fs_sm_info *sm_info = SM_I(sbi);
  
  	if (!sm_info)
  		return;
  	f2fs_destroy_flush_cmd_control(sbi, true);
  	destroy_discard_cmd_control(sbi);
  	destroy_dirty_segmap(sbi);
  	destroy_curseg(sbi);
  	destroy_free_segmap(sbi);
  	destroy_sit_info(sbi);
  	sbi->sm_info = NULL;
  	kvfree(sm_info);
  }
  
  int __init f2fs_create_segment_manager_caches(void)
  {
  	discard_entry_slab = f2fs_kmem_cache_create("f2fs_discard_entry",
  			sizeof(struct discard_entry));
  	if (!discard_entry_slab)
  		goto fail;
  
  	discard_cmd_slab = f2fs_kmem_cache_create("f2fs_discard_cmd",
  			sizeof(struct discard_cmd));
  	if (!discard_cmd_slab)
  		goto destroy_discard_entry;
  
  	sit_entry_set_slab = f2fs_kmem_cache_create("f2fs_sit_entry_set",
  			sizeof(struct sit_entry_set));
  	if (!sit_entry_set_slab)
  		goto destroy_discard_cmd;
  
  	inmem_entry_slab = f2fs_kmem_cache_create("f2fs_inmem_page_entry",
  			sizeof(struct inmem_pages));
  	if (!inmem_entry_slab)
  		goto destroy_sit_entry_set;
  	return 0;
  
  destroy_sit_entry_set:
  	kmem_cache_destroy(sit_entry_set_slab);
  destroy_discard_cmd:
  	kmem_cache_destroy(discard_cmd_slab);
  destroy_discard_entry:
  	kmem_cache_destroy(discard_entry_slab);
  fail:
  	return -ENOMEM;
  }
  
  void f2fs_destroy_segment_manager_caches(void)
  {
  	kmem_cache_destroy(sit_entry_set_slab);
  	kmem_cache_destroy(discard_cmd_slab);
  	kmem_cache_destroy(discard_entry_slab);
  	kmem_cache_destroy(inmem_entry_slab);
  }
  