[PATCH 2/2] f2fs: ro: don't start discard thread for readonly image

[Chao Yu]

[ 9299.893835] F2FS-fs (vdd): Allow to mount readonly mode only
mount: /mnt/f2fs: WARNING: source write-protected, mounted read-only.
root@qemu:/ ps -ef|grep f2fs
root          94       2  0 03:46 ?        00:00:00 [kworker/u17:0-f2fs_post_read_wq]
root        6282       2  0 06:21 ?        00:00:00 [f2fs_discard-253:48]

There will be no deletion in readonly image, let's skip starting
discard thread to save system resources.

Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
---
 fs/f2fs/segment.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index b486fe4485f9..cc27c5440188 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -2253,6 +2253,12 @@ int f2fs_start_discard_thread(struct f2fs_sb_info *sbi)
 	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
 	int err = 0;
 
+	if (f2fs_sb_has_readonly(sbi)) {
+		f2fs_info(sbi,
+			"Skip to start discard thread for readonly image");
+		return 0;
+	}
+
 	if (!f2fs_realtime_discard_enable(sbi))
 		return 0;
 
-- 
2.40.1