f2fs: ro: don't start discard thread for readonly image

[ 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@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 3b8aed8ca7d4cdd4932fa4226fc12af58415a55a..8014ea9f7a55f3176aa34313818359b3edf8441a 100644 (file)
--- 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;