Commit 43727527 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

f2fs: clarify and enhance the f2fs_gc flow 



This patch makes clearer the ambiguous f2fs_gc flow as follows.

1. Remove intermediate checkpoint condition during f2fs_gc
 (i.e., should_do_checkpoint() and GC_BLOCKED)

2. Remove unnecessary return values of f2fs_gc because of #1.
 (i.e., GC_NODE, GC_OK, etc)

3. Simplify write_checkpoint() because of #2.

4. Clarify the main f2fs_gc flow.
 o monitor how many freed sections during one iteration of do_garbage_collect().
 o do GC more without checkpoints if we can't get enough free sections.
 o do checkpoint once we've got enough free sections through forground GCs.

5. Adopt thread-logging (Slack-Space-Recycle) scheme more aggressively on data
  log types. See. get_ssr_segement()

Signed-off-by: default avatarJaegeuk Kim <jaegeuk.kim@samsung.com>
parent b1f1daf8

fs/f2fs/checkpoint.c

+4 −6
Original line number Diff line number Diff line
@@ -539,7 +539,7 @@ retry: 
/*

 * Freeze all the FS-operations for checkpoint.

 */

void block_operations(struct f2fs_sb_info *sbi)

static void block_operations(struct f2fs_sb_info *sbi)

{

	int t;

	struct writeback_control wbc = {
@@ -722,15 +722,13 @@ static void do_checkpoint(struct f2fs_sb_info *sbi, bool is_umount) 
/*

 * We guarantee that this checkpoint procedure should not fail.

 */

void write_checkpoint(struct f2fs_sb_info *sbi, bool blocked, bool is_umount)

void write_checkpoint(struct f2fs_sb_info *sbi, bool is_umount)

{

	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);

	unsigned long long ckpt_ver;



	if (!blocked) {

	mutex_lock(&sbi->cp_mutex);

	block_operations(sbi);

	}



	f2fs_submit_bio(sbi, DATA, true);

	f2fs_submit_bio(sbi, NODE, true);

fs/f2fs/f2fs.h

+1 −2
Original line number Diff line number Diff line
@@ -969,8 +969,7 @@ int get_valid_checkpoint(struct f2fs_sb_info *); 
void set_dirty_dir_page(struct inode *, struct page *);

void remove_dirty_dir_inode(struct inode *);

void sync_dirty_dir_inodes(struct f2fs_sb_info *);

void block_operations(struct f2fs_sb_info *);

void write_checkpoint(struct f2fs_sb_info *, bool, bool);

void write_checkpoint(struct f2fs_sb_info *, bool);

void init_orphan_info(struct f2fs_sb_info *);

int __init create_checkpoint_caches(void);

void destroy_checkpoint_caches(void);

fs/f2fs/gc.c

+41 −66
Original line number Diff line number Diff line
@@ -78,7 +78,8 @@ static int gc_thread_func(void *data) 


		sbi->bg_gc++;



		if (f2fs_gc(sbi) == GC_NONE)

		/* if return value is not zero, no victim was selected */

		if (f2fs_gc(sbi))

			wait_ms = GC_THREAD_NOGC_SLEEP_TIME;

		else if (wait_ms == GC_THREAD_NOGC_SLEEP_TIME)

			wait_ms = GC_THREAD_MAX_SLEEP_TIME;
@@ -360,7 +361,7 @@ static int check_valid_map(struct f2fs_sb_info *sbi, 
	sentry = get_seg_entry(sbi, segno);

	ret = f2fs_test_bit(offset, sentry->cur_valid_map);

	mutex_unlock(&sit_i->sentry_lock);

	return ret ? GC_OK : GC_NEXT;

	return ret;

}



/*
@@ -368,7 +369,7 @@ static int check_valid_map(struct f2fs_sb_info *sbi, 
 * On validity, copy that node with cold status, otherwise (invalid node)

 * ignore that.

 */

static int gc_node_segment(struct f2fs_sb_info *sbi,

static void gc_node_segment(struct f2fs_sb_info *sbi,

		struct f2fs_summary *sum, unsigned int segno, int gc_type)

{

	bool initial = true;
@@ -380,21 +381,12 @@ next_step: 
	for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {

		nid_t nid = le32_to_cpu(entry->nid);

		struct page *node_page;

		int err;



		/*

		 * It makes sure that free segments are able to write

		 * all the dirty node pages before CP after this CP.

		 * So let's check the space of dirty node pages.

		 */

		if (should_do_checkpoint(sbi)) {

			mutex_lock(&sbi->cp_mutex);

			block_operations(sbi);

			return GC_BLOCKED;

		}

		/* stop BG_GC if there is not enough free sections. */

		if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))

			return;



		err = check_valid_map(sbi, segno, off);

		if (err == GC_NEXT)

		if (check_valid_map(sbi, segno, off) == 0)

			continue;



		if (initial) {
@@ -424,7 +416,6 @@ next_step: 
		};

		sync_node_pages(sbi, 0, &wbc);

	}

	return GC_DONE;

}



/*
@@ -467,13 +458,13 @@ static int check_dnode(struct f2fs_sb_info *sbi, struct f2fs_summary *sum, 


	node_page = get_node_page(sbi, nid);

	if (IS_ERR(node_page))

		return GC_NEXT;

		return 0;



	get_node_info(sbi, nid, dni);



	if (sum->version != dni->version) {

		f2fs_put_page(node_page, 1);

		return GC_NEXT;

		return 0;

	}



	*nofs = ofs_of_node(node_page);
@@ -481,8 +472,8 @@ static int check_dnode(struct f2fs_sb_info *sbi, struct f2fs_summary *sum, 
	f2fs_put_page(node_page, 1);



	if (source_blkaddr != blkaddr)

		return GC_NEXT;

	return GC_OK;

		return 0;

	return 1;

}



static void move_data_page(struct inode *inode, struct page *page, int gc_type)
@@ -523,13 +514,13 @@ out: 
 * If the parent node is not valid or the data block address is different,

 * the victim data block is ignored.

 */

static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,

static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,

		struct list_head *ilist, unsigned int segno, int gc_type)

{

	struct super_block *sb = sbi->sb;

	struct f2fs_summary *entry;

	block_t start_addr;

	int err, off;

	int off;

	int phase = 0;



	start_addr = START_BLOCK(sbi, segno);
@@ -543,20 +534,11 @@ next_step: 
		unsigned int ofs_in_node, nofs;

		block_t start_bidx;



		/*

		 * It makes sure that free segments are able to write

		 * all the dirty node pages before CP after this CP.

		 * So let's check the space of dirty node pages.

		 */

		if (should_do_checkpoint(sbi)) {

			mutex_lock(&sbi->cp_mutex);

			block_operations(sbi);

			err = GC_BLOCKED;

			goto stop;

		}

		/* stop BG_GC if there is not enough free sections. */

		if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))

			return;



		err = check_valid_map(sbi, segno, off);

		if (err == GC_NEXT)

		if (check_valid_map(sbi, segno, off) == 0)

			continue;



		if (phase == 0) {
@@ -565,8 +547,7 @@ next_step: 
		}



		/* Get an inode by ino with checking validity */

		err = check_dnode(sbi, entry, &dni, start_addr + off, &nofs);

		if (err == GC_NEXT)

		if (check_dnode(sbi, entry, &dni, start_addr + off, &nofs) == 0)

			continue;



		if (phase == 1) {
@@ -606,11 +587,9 @@ next_iput: 
	}

	if (++phase < 4)

		goto next_step;

	err = GC_DONE;

stop:



	if (gc_type == FG_GC)

		f2fs_submit_bio(sbi, DATA, true);

	return err;

}



static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
@@ -624,17 +603,16 @@ static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim, 
	return ret;

}



static int do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,

static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,

				struct list_head *ilist, int gc_type)

{

	struct page *sum_page;

	struct f2fs_summary_block *sum;

	int ret = GC_DONE;



	/* read segment summary of victim */

	sum_page = get_sum_page(sbi, segno);

	if (IS_ERR(sum_page))

		return GC_ERROR;

		return;



	/*

	 * CP needs to lock sum_page. In this time, we don't need
@@ -646,17 +624,16 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno, 


	switch (GET_SUM_TYPE((&sum->footer))) {

	case SUM_TYPE_NODE:

		ret = gc_node_segment(sbi, sum->entries, segno, gc_type);

		gc_node_segment(sbi, sum->entries, segno, gc_type);

		break;

	case SUM_TYPE_DATA:

		ret = gc_data_segment(sbi, sum->entries, ilist, segno, gc_type);

		gc_data_segment(sbi, sum->entries, ilist, segno, gc_type);

		break;

	}

	stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer)));

	stat_inc_call_count(sbi->stat_info);



	f2fs_put_page(sum_page, 0);

	return ret;

}



int f2fs_gc(struct f2fs_sb_info *sbi)
@@ -664,40 +641,38 @@ int f2fs_gc(struct f2fs_sb_info *sbi) 
	struct list_head ilist;

	unsigned int segno, i;

	int gc_type = BG_GC;

	int gc_status = GC_NONE;

	int nfree = 0;

	int ret = -1;



	INIT_LIST_HEAD(&ilist);

gc_more:

	if (!(sbi->sb->s_flags & MS_ACTIVE))

		goto stop;



	if (gc_type == BG_GC && has_not_enough_free_secs(sbi))

	if (gc_type == BG_GC && has_not_enough_free_secs(sbi, nfree))

		gc_type = FG_GC;



	if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE))

		goto stop;

	ret = 0;



	for (i = 0; i < sbi->segs_per_sec; i++) {

		/*

		 * do_garbage_collect will give us three gc_status:

		 * GC_ERROR, GC_DONE, and GC_BLOCKED.

		 * If GC is finished uncleanly, we have to return

		 * the victim to dirty segment list.

		 */

		gc_status = do_garbage_collect(sbi, segno + i, &ilist, gc_type);

		if (gc_status != GC_DONE)

			break;

	}

	if (has_not_enough_free_secs(sbi)) {

		write_checkpoint(sbi, (gc_status == GC_BLOCKED), false);

		if (has_not_enough_free_secs(sbi))

	for (i = 0; i < sbi->segs_per_sec; i++)

		do_garbage_collect(sbi, segno + i, &ilist, gc_type);



	if (gc_type == FG_GC &&

			get_valid_blocks(sbi, segno, sbi->segs_per_sec) == 0)

		nfree++;



	if (has_not_enough_free_secs(sbi, nfree))

		goto gc_more;

	}



	if (gc_type == FG_GC)

		write_checkpoint(sbi, false);

stop:

	mutex_unlock(&sbi->gc_mutex);



	put_gc_inode(&ilist);

	return gc_status;

	return ret;

}



void build_gc_manager(struct f2fs_sb_info *sbi)

fs/f2fs/gc.h

+0 −16
Original line number Diff line number Diff line
@@ -22,15 +22,6 @@ 
/* Search max. number of dirty segments to select a victim segment */

#define MAX_VICTIM_SEARCH	20



enum {

	GC_NONE = 0,

	GC_ERROR,

	GC_OK,

	GC_NEXT,

	GC_BLOCKED,

	GC_DONE,

};



struct f2fs_gc_kthread {

	struct task_struct *f2fs_gc_task;

	wait_queue_head_t gc_wait_queue_head;
@@ -103,10 +94,3 @@ static inline int is_idle(struct f2fs_sb_info *sbi) 
	struct request_list *rl = &q->root_rl;

	return !(rl->count[BLK_RW_SYNC]) && !(rl->count[BLK_RW_ASYNC]);

}
 


static inline bool should_do_checkpoint(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);

	return free_sections(sbi) <= (node_secs + 2 * dent_secs + 2);

}

fs/f2fs/node.c

+1 −1
Original line number Diff line number Diff line
@@ -1135,7 +1135,7 @@ static int f2fs_write_node_pages(struct address_space *mapping, 


	/* First check balancing cached NAT entries */

	if (try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK)) {

		write_checkpoint(sbi, false, false);

		write_checkpoint(sbi, false);

		return 0;

	}

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