f2fs: add ovp valid_blocks check for bg gc victim to fg_gc

For foreground gc, greedy algorithm should be adapted, which makes
this formula work well:

	(2 * (100 / config.overprovision + 1) + 6)

But currently, we fg_gc have a prior to select bg_gc victim segments to gc
first, these victims are selected by cost-benefit algorithm, we can't guarantee
such segments have the small valid blocks, which may destroy the f2fs rule, on
the worstest case, would consume all the free segments.

This patch fix this by add a filter in check_bg_victims, if segment's has # of
valid blocks over overprovision ratio, skip such segments.

Cc: <stable@vger.kernel.org>
Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 7b5e287ac127c90bf4f299ca773ad3d1ba4841ae..146cc71ff91c56d4fb5a50ab0bdf0b3559acc464 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -890,6 +890,9 @@ struct f2fs_sb_info {
        struct f2fs_gc_kthread  *gc_thread;     /* GC thread */
        unsigned int cur_victim_sec;            /* current victim section num */
 
+       /* threshold for converting bg victims for fg */
+       u64 fggc_threshold;
+
        /* maximum # of trials to find a victim segment for SSR and GC */
        unsigned int max_victim_search;
 

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 5ee258ebf6cad6bbbc6686bfdc3d826d89d0df18..e93aecb0138b057c198d13c63811772c215f19af 100644 (file)
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -166,7 +166,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
                p->ofs_unit = sbi->segs_per_sec;
        }
 
-       if (p->max_search > sbi->max_victim_search)
+       /* we need to check every dirty segments in the FG_GC case */
+       if (gc_type != FG_GC && p->max_search > sbi->max_victim_search)
                p->max_search = sbi->max_victim_search;
 
        p->offset = sbi->last_victim[p->gc_mode];
@@ -199,6 +200,10 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
        for_each_set_bit(secno, dirty_i->victim_secmap, MAIN_SECS(sbi)) {
                if (sec_usage_check(sbi, secno))
                        continue;
+
+               if (no_fggc_candidate(sbi, secno))
+                       continue;
+
                clear_bit(secno, dirty_i->victim_secmap);
                return secno * sbi->segs_per_sec;
        }
@@ -322,13 +327,15 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
                        nsearched++;
                }
 
-
                secno = GET_SECNO(sbi, segno);
 
                if (sec_usage_check(sbi, secno))
                        goto next;
                if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
                        goto next;
+               if (gc_type == FG_GC && p.alloc_mode == LFS &&
+                                       no_fggc_candidate(sbi, secno))
+                       goto next;
 
                cost = get_gc_cost(sbi, segno, &p);
 
@@ -985,5 +992,16 @@ stop:
 
 void build_gc_manager(struct f2fs_sb_info *sbi)
 {
+       u64 main_count, resv_count, ovp_count, blocks_per_sec;
+
        DIRTY_I(sbi)->v_ops = &default_v_ops;
+
+       /* threshold of # of valid blocks in a section for victims of FG_GC */
+       main_count = SM_I(sbi)->main_segments << sbi->log_blocks_per_seg;
+       resv_count = SM_I(sbi)->reserved_segments << sbi->log_blocks_per_seg;
+       ovp_count = SM_I(sbi)->ovp_segments << sbi->log_blocks_per_seg;
+       blocks_per_sec = sbi->blocks_per_seg * sbi->segs_per_sec;
+
+       sbi->fggc_threshold = div_u64((main_count - ovp_count) * blocks_per_sec,
+                                       (main_count - resv_count));
 }

diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index 5cb5755c75d910557d1151ffd84890688a33cc88..f4020f141d8316acdb0fe94917bda3003d45e724 100644 (file)
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -716,6 +716,15 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
                                - (base + 1) + type;
 }
 
+static inline bool no_fggc_candidate(struct f2fs_sb_info *sbi,
+                                               unsigned int secno)
+{
+       if (get_valid_blocks(sbi, secno, sbi->segs_per_sec) >=
+                                               sbi->fggc_threshold)
+               return true;
+       return false;
+}
+
 static inline bool sec_usage_check(struct f2fs_sb_info *sbi, unsigned int secno)
 {
        if (IS_CURSEC(sbi, secno) || (sbi->cur_victim_sec == secno))