bcachefs: Device state is now a runtime option

Other options can normally be set at runtime via sysfs, no reason for
this one not to be as well - it just doesn't support the degraded flags
argument this way, that requires the ioctl.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/opts.c

@@ -482,9 +482,16 @@ void bch2_opts_to_text(struct printbuf *out,
 
 int bch2_opt_check_may_set(struct bch_fs *c, struct bch_dev *ca, int id, u64 v)
 {
+	lockdep_assert_held(&c->state_lock);
+
 	int ret = 0;
 
 	switch (id) {
+	case Opt_state:
+		if (ca)
+			return __bch2_dev_set_state(c, ca, v, BCH_FORCE_IF_DEGRADED);
+		break;
+
 	case Opt_compression:
 	case Opt_background_compression:
 		ret = bch2_check_set_has_compressed_data(c, v);

fs/bcachefs/opts.h

@@ -495,7 +495,7 @@ enum fsck_err_opts {
 	  NULL,		"Skip submit_bio() for data reads and writes, "	\
 			"for performance testing purposes")		\
 	x(state,			u64,				\
-	  OPT_DEVICE,							\
+	  OPT_DEVICE|OPT_RUNTIME,					\
 	  OPT_STR(bch2_member_states),					\
 	  BCH_MEMBER_STATE,		BCH_MEMBER_STATE_rw,		\
 	  "state",	"rw,ro,failed,spare")				\

fs/bcachefs/sysfs.c

@@ -631,6 +631,8 @@ static ssize_t sysfs_opt_store(struct bch_fs *c,
 	if (unlikely(!bch2_write_ref_tryget(c, BCH_WRITE_REF_sysfs)))
 		return -EROFS;
 
+	down_write(&c->state_lock);
+
 	char *tmp = kstrdup(buf, GFP_KERNEL);
 	if (!tmp) {
 		ret = -ENOMEM;
@@ -664,6 +666,7 @@ static ssize_t sysfs_opt_store(struct bch_fs *c,
 
 	ret = size;
 err:
+	up_write(&c->state_lock);
 	bch2_write_ref_put(c, BCH_WRITE_REF_sysfs);
 	return ret;
 }