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Commit 408e9375 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

f2fs: revisit the f2fs_gc flow 



I'd like to revisit the f2fs_gc flow and rewrite as follows.

1. In practical, the nGC parameter of f2fs_gc is meaningless. So, let's
  remove it.
2. Background GC marks victim blocks as dirty one at a time.
3. Foreground GC should do cleaning job until acquiring enough free
  sections. Afterwards, it needs to do checkpoint.

Signed-off-by: default avatarJaegeuk Kim <jaegeuk.kim@samsung.com>
parent c335a869

fs/f2fs/f2fs.h

+1 −1
Original line number Diff line number Diff line
@@ -986,7 +986,7 @@ int do_write_data_page(struct page *); 
int start_gc_thread(struct f2fs_sb_info *);

void stop_gc_thread(struct f2fs_sb_info *);

block_t start_bidx_of_node(unsigned int);

int f2fs_gc(struct f2fs_sb_info *, int);

int f2fs_gc(struct f2fs_sb_info *);

void build_gc_manager(struct f2fs_sb_info *);

int create_gc_caches(void);

void destroy_gc_caches(void);

fs/f2fs/gc.c

+21 −39
Original line number Diff line number Diff line
@@ -78,7 +78,7 @@ static int gc_thread_func(void *data) 


		sbi->bg_gc++;



		if (f2fs_gc(sbi, 1) == GC_NONE)

		if (f2fs_gc(sbi) == GC_NONE)

			wait_ms = GC_THREAD_NOGC_SLEEP_TIME;

		else if (wait_ms == GC_THREAD_NOGC_SLEEP_TIME)

			wait_ms = GC_THREAD_MAX_SLEEP_TIME;
@@ -651,37 +651,23 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno, 
	return ret;

}



int f2fs_gc(struct f2fs_sb_info *sbi, int nGC)

int f2fs_gc(struct f2fs_sb_info *sbi)

{

	unsigned int segno;

	int old_free_secs, cur_free_secs;

	int gc_status, nfree;

	struct list_head ilist;

	unsigned int segno, i;

	int gc_type = BG_GC;

	int gc_status = GC_NONE;



	INIT_LIST_HEAD(&ilist);

gc_more:

	nfree = 0;

	gc_status = GC_NONE;

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

		goto stop;



	if (has_not_enough_free_secs(sbi))

		old_free_secs = reserved_sections(sbi);

	else

		old_free_secs = free_sections(sbi);



	while (sbi->sb->s_flags & MS_ACTIVE) {

		int i;

	if (has_not_enough_free_secs(sbi))

		gc_type = FG_GC;



		cur_free_secs = free_sections(sbi) + nfree;



		/* We got free space successfully. */

		if (nGC < cur_free_secs - old_free_secs)

			break;



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

			break;

		goto stop;



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

		/*
@@ -690,23 +676,19 @@ int f2fs_gc(struct f2fs_sb_info *sbi, int nGC) 
		 * 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);

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

		if (gc_status != GC_DONE)

				goto stop;

			nfree++;

		}

			break;

	}

stop:

	if (has_not_enough_free_secs(sbi) || gc_status == GC_BLOCKED) {

	if (has_not_enough_free_secs(sbi)) {

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

		if (nfree)

		if (has_not_enough_free_secs(sbi))

			goto gc_more;

	}

stop:

	mutex_unlock(&sbi->gc_mutex);



	put_gc_inode(&ilist);

	BUG_ON(!list_empty(&ilist));

	return gc_status;

}

fs/f2fs/segment.c

+1 −1
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi) 
	 */

	if (has_not_enough_free_secs(sbi)) {

		mutex_lock(&sbi->gc_mutex);

		f2fs_gc(sbi, 1);

		f2fs_gc(sbi);

	}

}