btrfs: publish per-super features in sysfs

[mirror_ubuntu-bionic-kernel.git] / fs / btrfs / sysfs.c

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 5b326cd60a4aa3c048eefe730312248d73cf47ba..832cf62151ffbf43998e98efe0457f6181a8e432 100644 (file)
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -26,20 +26,149 @@
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
+#include "sysfs.h"
+
+static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj);
+
+static u64 get_features(struct btrfs_fs_info *fs_info,
+                       enum btrfs_feature_set set)
+{
+       struct btrfs_super_block *disk_super = fs_info->super_copy;
+       if (set == FEAT_COMPAT)
+               return btrfs_super_compat_flags(disk_super);
+       else if (set == FEAT_COMPAT_RO)
+               return btrfs_super_compat_ro_flags(disk_super);
+       else
+               return btrfs_super_incompat_flags(disk_super);
+}
+
+static ssize_t btrfs_feature_attr_show(struct kobject *kobj,
+                                      struct kobj_attribute *a, char *buf)
+{
+       int val = 0;
+       struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+       if (fs_info) {
+               struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
+               u64 features = get_features(fs_info, fa->feature_set);
+               if (features & fa->feature_bit)
+                       val = 1;
+       }
+
+       return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+
+static umode_t btrfs_feature_visible(struct kobject *kobj,
+                                    struct attribute *attr, int unused)
+{
+       struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+       umode_t mode = attr->mode;
+
+       if (fs_info) {
+               struct btrfs_feature_attr *fa;
+               u64 features;
+
+               fa = attr_to_btrfs_feature_attr(attr);
+               features = get_features(fs_info, fa->feature_set);
+
+               if (!(features & fa->feature_bit))
+                       mode = 0;
+       }
+
+       return mode;
+}
+
+BTRFS_FEAT_ATTR_INCOMPAT(mixed_backref, MIXED_BACKREF);
+BTRFS_FEAT_ATTR_INCOMPAT(default_subvol, DEFAULT_SUBVOL);
+BTRFS_FEAT_ATTR_INCOMPAT(mixed_groups, MIXED_GROUPS);
+BTRFS_FEAT_ATTR_INCOMPAT(compress_lzo, COMPRESS_LZO);
+BTRFS_FEAT_ATTR_INCOMPAT(compress_lzov2, COMPRESS_LZOv2);
+BTRFS_FEAT_ATTR_INCOMPAT(big_metadata, BIG_METADATA);
+BTRFS_FEAT_ATTR_INCOMPAT(extended_iref, EXTENDED_IREF);
+BTRFS_FEAT_ATTR_INCOMPAT(raid56, RAID56);
+BTRFS_FEAT_ATTR_INCOMPAT(skinny_metadata, SKINNY_METADATA);
+
+static struct attribute *btrfs_supported_feature_attrs[] = {
+       BTRFS_FEAT_ATTR_PTR(mixed_backref),
+       BTRFS_FEAT_ATTR_PTR(default_subvol),
+       BTRFS_FEAT_ATTR_PTR(mixed_groups),
+       BTRFS_FEAT_ATTR_PTR(compress_lzo),
+       BTRFS_FEAT_ATTR_PTR(compress_lzov2),
+       BTRFS_FEAT_ATTR_PTR(big_metadata),
+       BTRFS_FEAT_ATTR_PTR(extended_iref),
+       BTRFS_FEAT_ATTR_PTR(raid56),
+       BTRFS_FEAT_ATTR_PTR(skinny_metadata),
+       NULL
+};
+
+static const struct attribute_group btrfs_feature_attr_group = {
+       .name = "features",
+       .is_visible = btrfs_feature_visible,
+       .attrs = btrfs_supported_feature_attrs,
+};
+
+static void btrfs_release_super_kobj(struct kobject *kobj)
+{
+       struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+       complete(&fs_info->kobj_unregister);
+}
+
+static struct kobj_type btrfs_ktype = {
+       .sysfs_ops      = &kobj_sysfs_ops,
+       .release        = btrfs_release_super_kobj,
+};
+
+static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)
+{
+       if (kobj->ktype != &btrfs_ktype)
+               return NULL;
+       return container_of(kobj, struct btrfs_fs_info, super_kobj);
+}
+
+void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
+{
+       kobject_del(&fs_info->super_kobj);
+       kobject_put(&fs_info->super_kobj);
+       wait_for_completion(&fs_info->kobj_unregister);
+}
 
 /* /sys/fs/btrfs/ entry */
 static struct kset *btrfs_kset;
 
+int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
+{
+       int error;
+
+       init_completion(&fs_info->kobj_unregister);
+       fs_info->super_kobj.kset = btrfs_kset;
+       error = kobject_init_and_add(&fs_info->super_kobj, &btrfs_ktype, NULL,
+                                    "%pU", fs_info->fsid);
+
+       error = sysfs_create_group(&fs_info->super_kobj,
+                                  &btrfs_feature_attr_group);
+       if (error)
+               btrfs_sysfs_remove_one(fs_info);
+       return error;
+}
+
 int btrfs_init_sysfs(void)
 {
+       int ret;
        btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj);
        if (!btrfs_kset)
                return -ENOMEM;
+
+       ret = sysfs_create_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
+       if (ret) {
+               kset_unregister(btrfs_kset);
+               return ret;
+       }
+
        return 0;
 }
 
 void btrfs_exit_sysfs(void)
 {
+       sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
        kset_unregister(btrfs_kset);
 }