[PATCH v2 2/2] rbd: refresh features and set the disk to readonly if there is unsupported bit

[Dongsheng Yang <dongsheng.yang@xxxxxxxxxxxx>]

If there is unsupported feature enabled after rbd map, we will noticed it in
refreshing, then we need to set the disk readonly.

For example, if we enabled the object-map feature after rbd map, as we don't
support object-map in kernel rbd currently,  we should avoid user to write
rbd device. And set dist to read-write when we disable the unsupported features.

Signed-off-by: Dongsheng Yang <dongsheng.yang@xxxxxxxxxxxx>
---
V1:
	- set disk to read-write when we disabled the unsupported features.

 drivers/block/rbd.c | 44 +++++++++++++++++++++++++-------------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index eb59b93..cf9c27a 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -753,6 +753,7 @@ enum {
 struct rbd_options {
 	int	queue_depth;
 	bool	read_only;
+	bool	read_only_need_restore;
 	bool	lock_on_read;
 	bool	exclusive;
 };
@@ -4463,17 +4464,6 @@ static int _rbd_dev_v2_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
 	return 0;
 }
 
-static int rbd_dev_v2_features(struct rbd_device *rbd_dev)
-{
-	u64 features = 0;
-	int ret = _rbd_dev_v2_snap_features(rbd_dev, CEPH_NOSNAP, features);
-	if (ret)
-		return ret
-
-	rbd_dev->header.features = features
-	return 0;
-}
-
 static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
 {
 	struct rbd_spec *parent_spec;
@@ -4938,12 +4928,35 @@ static const char *rbd_dev_v2_snap_name(struct rbd_device *rbd_dev,
 static int rbd_dev_v2_header_info(struct rbd_device *rbd_dev)
 {
 	bool first_time = rbd_dev->header.object_prefix == NULL;
+	u64 features = 0;
 	int ret;
 
 	ret = rbd_dev_v2_image_size(rbd_dev);
 	if (ret)
 		return ret;
 
+	ret = _rbd_dev_v2_snap_features(rbd_dev, CEPH_NOSNAP,
+					&features);
+	if (ret) {
+		if (-ENXIO == ret && !first_time) {
+			if (!rbd_dev->opts->read_only) {
+				rbd_dev->opts->read_only = true;
+				rbd_dev->opts->read_only_need_restore = true;
+				set_disk_ro(rbd_dev->disk,
+						rbd_dev->opts->read_only);
+			}
+		} else {
+			return ret;
+		}
+	} else {
+		if (rbd_dev->opts->read_only_need_restore) {
+			rbd_dev->opts->read_only = false;
+			rbd_dev->opts->read_only_need_restore = false;
+			set_disk_ro(rbd_dev->disk, rbd_dev->opts->read_only);
+		}
+	}
+	rbd_dev->mapping.features = rbd_dev->header.features = features;
+
 	if (first_time) {
 		ret = rbd_dev_v2_header_onetime(rbd_dev);
 		if (ret)
@@ -5143,6 +5156,7 @@ static int rbd_add_parse_args(const char *buf,
 		goto out_mem;
 
 	rbd_opts->read_only = RBD_READ_ONLY_DEFAULT;
+	rbd_opts->read_only_need_restore = false;
 	rbd_opts->queue_depth = RBD_QUEUE_DEPTH_DEFAULT;
 	rbd_opts->lock_on_read = RBD_LOCK_ON_READ_DEFAULT;
 	rbd_opts->exclusive = RBD_EXCLUSIVE_DEFAULT;
@@ -5344,14 +5358,6 @@ static int rbd_dev_v2_header_onetime(struct rbd_device *rbd_dev)
 	if (ret)
 		goto out_err;
 
-	/*
-	 * Get the and check features for the image.  Currently the
-	 * features are assumed to never change.
-	 */
-	ret = rbd_dev_v2_features(rbd_dev);
-	if (ret)
-		goto out_err;
-
 	/* If the image supports fancy striping, get its parameters */
 
 	if (rbd_dev->header.features & RBD_FEATURE_STRIPINGV2) {
-- 
1.8.3.1


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