Re: [PATCH] f2fs: add bug_on when f2fs_gc even fails to get one victim

[Yunlong Song]

Hi, Jay,
    I think it should not happen when need_gc == true but total_freed 
==0, so I add it as bug_on to let it panic at once. And even CHECK_FS is 
closed, this can also printk WARNING message for notice.

On 2017/10/13 7:23, Jaegeuk Kim wrote:
Hi Yunlong,

On 10/11, Yunlong Song wrote:
This can help us to debug on some corner case.

Signed-off-by: Yunlong Song <yunlong.s...@huawei.com>
---
  fs/f2fs/gc.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 197ebf4..960503e 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -986,6 +986,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
                .ilist = LIST_HEAD_INIT(gc_list.ilist),
                .iroot = RADIX_TREE_INIT(GFP_NOFS),
        };
+       bool need_gc = false;
  
  	trace_f2fs_gc_begin(sbi->sb, sync, background,
                                get_pages(sbi, F2FS_DIRTY_NODES),
@@ -1018,8 +1019,10 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
                        if (ret)
                                goto stop;
                }
-               if (has_not_enough_free_secs(sbi, 0, 0))
+               if (has_not_enough_free_secs(sbi, 0, 0)) {
                        gc_type = FG_GC;
+                       need_gc = true;
+               }
        }
  
  	/* f2fs_balance_fs doesn't need to do BG_GC in critical path. */
@@ -1028,6 +1031,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
                goto stop;
        }
        if (!__get_victim(sbi, &segno, gc_type)) {
+               f2fs_bug_on(sbi, !total_freed && need_gc);
How about this, if this is for debugging purpose?

                if (!total_freed && need_gc)
                        f2fs_msg(...);

It's not a good way to define a value for f2fs_bug_on(), since it is only
activated by CHECK_FS config.

Thanks,

                ret = -ENODATA;
                goto stop;
        }
--
1.8.5.2
.


--
Thanks,
Yunlong Song