[PATCH] f2fs: fix to check bio after __blkdev_issue_discard()

[Chao Yu]

Previously, __blkdev_issue_discard() will always returned valid bio,
after commit e8b4869bc78d ("block: add a blk_alloc_discard_bio helper"),
it can return bio w/ NULL value, which may trigger panic or warning
in __submit_discard_cmd(), let's fix to check bio instread of return
value after __blkdev_issue_discard().

Cc: stable@xxxxxxxxxx
Fixes: e8b4869bc78d ("block: add a blk_alloc_discard_bio helper")
Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
---
 fs/f2fs/segment.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8375dca7ed9e..44c0cefbb5a9 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1351,7 +1351,7 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
 					SECTOR_FROM_BLOCK(len),
 					GFP_NOFS, &bio);
 		}
-		if (err) {
+		if (err || bio == NULL) {
 			spin_lock_irqsave(&dc->lock, flags);
 			if (dc->state == D_PARTIAL)
 				dc->state = D_SUBMIT;
-- 
2.49.0