bcachefs: Check for rw before setting opts via sysfs

This isn't a correctness issue, it just eliminates errors in the dmesg
log when we're RO.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

diff --git a/fs/bcachefs/sysfs.c b/fs/bcachefs/sysfs.c
index 49e38859bff819b1d3c21e54504b46473b5fd4d3..afcb5ad1aa620318355b3dcf92a994cd48515001 100644 (file)
--- a/fs/bcachefs/sysfs.c
+++ b/fs/bcachefs/sysfs.c
@@ -611,19 +611,28 @@ STORE(bch2_fs_opts_dir)
        char *tmp;
        u64 v;
 
+       /*
+        * We don't need to take c->writes for correctness, but it eliminates an
+        * unsightly error message in the dmesg log when we're RO:
+        */
+       if (unlikely(!percpu_ref_tryget(&c->writes)))
+               return -EROFS;
+
        tmp = kstrdup(buf, GFP_KERNEL);
-       if (!tmp)
-               return -ENOMEM;
+       if (!tmp) {
+               ret = -ENOMEM;
+               goto err;
+       }
 
        ret = bch2_opt_parse(c, NULL, opt, strim(tmp), &v);
        kfree(tmp);
 
        if (ret < 0)
-               return ret;
+               goto err;
 
        ret = bch2_opt_check_may_set(c, id, v);
        if (ret < 0)
-               return ret;
+               goto err;
 
        bch2_opt_set_sb(c, opt, v);
        bch2_opt_set_by_id(&c->opts, id, v);
@@ -634,7 +643,10 @@ STORE(bch2_fs_opts_dir)
                rebalance_wakeup(c);
        }
 
-       return size;
+       ret = size;
+err:
+       percpu_ref_put(&c->writes);
+       return ret;
 }
 SYSFS_OPS(bch2_fs_opts_dir);