[PATCH 4.9 082/241] f2fs: relax node version check for victim data in gc

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>


[ Upstream commit c13ff37e359bb3eacf4e1760dcea8d9760aa7459 ]

- has_not_enough_free_secs
node_secs: 0  dent_secs: 0  freed:0  free_segments:103  reserved:104

          - f2fs_gc
             - get_victim_by_default
alloc_mode 0, gc_mode 1, max_search 2672, offset 4654, ofs_unit 1

                - do_garbage_collect
start_segno 3976, end_segno 3977   type 0

                  - is_alive
nid 22797, blkaddr 2131882, ofs_in_node 0, version 0x8/0x0

                   - gc_data_segment 766, segno 3976, block 512/426 not alive

So, this patch fixes subtle corrupted case where node version does not match
to summary version which results in infinite loop by gc.

Reported-by: Yunlei He <heyunlei@xxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/f2fs/gc.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -538,8 +538,10 @@ static bool is_alive(struct f2fs_sb_info
 	get_node_info(sbi, nid, dni);
 
 	if (sum->version != dni->version) {
-		f2fs_put_page(node_page, 1);
-		return false;
+		f2fs_msg(sbi->sb, KERN_WARNING,
+				"%s: valid data with mismatched node version.",
+				__func__);
+		set_sbi_flag(sbi, SBI_NEED_FSCK);
 	}
 
 	*nofs = ofs_of_node(node_page);