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: Jaegeuk Kim <jaegeuk.kim@samsung.com>

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 2807132..285e43d 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -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);

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index b0ec721..b4dd90c 100644 (file)
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -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;
@@ -651,62 +651,44 @@ 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;
+               gc_type = FG_GC;
 
-               cur_free_secs = free_sections(sbi) + nfree;
+       if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE))
+               goto stop;
 
-               /* We got free space successfully. */
-               if (nGC < cur_free_secs - old_free_secs)
-                       break;
-
-               if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE))
+       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;
-
-               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)
-                               goto stop;
-                       nfree++;
-               }
        }
-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;
 }
 

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index de62409..4b00990 100644 (file)
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -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);
        }
 }