f2fs: get victim segment again after new cp

Previous selected segment may become free after write_checkpoint,
if we do garbage collect on this segment, and then new_curseg happen
to reuse it, it may cause f2fs_bug_on as below.

	panic+0x154/0x29c
	do_garbage_collect+0x15c/0xaf4
	f2fs_gc+0x2dc/0x444
	f2fs_balance_fs.part.22+0xcc/0x14c
	f2fs_balance_fs+0x28/0x34
	f2fs_map_blocks+0x5ec/0x790
	f2fs_preallocate_blocks+0xe0/0x100
	f2fs_file_write_iter+0x64/0x11c
	new_sync_write+0xac/0x11c
	vfs_write+0x144/0x1e4
	SyS_write+0x60/0xc0

Here, maybe we check sit and ssa type during reset_curseg. So, we check
segment is stale or not, and select a new victim to avoid this.

Signed-off-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index de6c41c32c62..06cfb94cc3db 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -908,10 +908,13 @@ gc_more:
                  * enough free sections, we should flush dent/node blocks and do
                  * garbage collections.
                  */
-                if (__get_victim(sbi, &segno, gc_type) || prefree_segments(sbi))
+                if (__get_victim(sbi, &segno, gc_type) ||
+                                                prefree_segments(sbi)) {
                         write_checkpoint(sbi, &cpc);
-                else if (has_not_enough_free_secs(sbi, 0))
+                        segno = NULL_SEGNO;
+                } else if (has_not_enough_free_secs(sbi, 0)) {
                         write_checkpoint(sbi, &cpc);
+                }
         }
 
         if (segno == NULL_SEGNO && !__get_victim(sbi, &segno, gc_type))