btrfs: sysfs: introduce helper for syncing bits with sysfs files

The files under /sys/fs/UUID/features get out of sync with the actual
incompat bits set for the filesystem if they change after mount. We're
going to sync them and need a helper to do that.

Signed-off-by: David Sterba <dsterba@suse.com>

2 files changed, 33 insertions, 0 deletions

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 906f7ed6fc80..6986886243bf 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -782,6 +782,36 @@ failure:
         return error;
 }
 
+
+/*
+ * Change per-fs features in /sys/fs/btrfs/UUID/features to match current
+ * values in superblock. Call after any changes to incompat/compat_ro flags
+ */
+void btrfs_sysfs_feature_update(struct btrfs_fs_info *fs_info,
+                u64 bit, enum btrfs_feature_set set)
+{
+        struct btrfs_fs_devices *fs_devs;
+        struct kobject *fsid_kobj;
+        u64 features;
+        int ret;
+
+        if (!fs_info)
+                return;
+
+        features = get_features(fs_info, set);
+        ASSERT(bit & supported_feature_masks[set]);
+
+        fs_devs = fs_info->fs_devices;
+        fsid_kobj = &fs_devs->fsid_kobj;
+
+        /*
+         * FIXME: this is too heavy to update just one value, ideally we'd like
+         * to use sysfs_update_group but some refactoring is needed first.
+         */
+        sysfs_remove_group(fsid_kobj, &btrfs_feature_attr_group);
+        ret = sysfs_create_group(fsid_kobj, &btrfs_feature_attr_group);
+}
+
 static int btrfs_init_debugfs(void)
 {
 #ifdef CONFIG_DEBUG_FS
diff --git a/fs/btrfs/sysfs.h b/fs/btrfs/sysfs.h
index 72408e2c4ea8..d7da1a4c2f6c 100644
--- a/fs/btrfs/sysfs.h
+++ b/fs/btrfs/sysfs.h
@@ -90,4 +90,7 @@ int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
                                 struct kobject *parent);
 int btrfs_sysfs_add_device(struct btrfs_fs_devices *fs_devs);
 void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs);
+void btrfs_sysfs_feature_update(struct btrfs_fs_info *fs_info,
+                u64 bit, enum btrfs_feature_set set);
+
 #endif /* _BTRFS_SYSFS_H_ */