@@ -96,6 +96,23 @@ static void init_feature_set_attrs(enum
}
}
+static u64 writeable_mask[FEAT_MAX] = {
+ [FEAT_COMPAT] = BTRFS_FEATURE_COMPAT_SAFE_SET |
+ BTRFS_FEATURE_COMPAT_SAFE_CLEAR,
+ [FEAT_COMPAT_RO] = BTRFS_FEATURE_COMPAT_RO_SAFE_SET |
+ BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR,
+ [FEAT_INCOMPAT] = BTRFS_FEATURE_INCOMPAT_SAFE_SET |
+ BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR,
+};
+
+static inline umode_t fa_mode(struct btrfs_feature_attr *fa)
+{
+ umode_t mode = S_IRUGO;
+ if (writeable_mask[fa->feature_set] & fa->feature_bit)
+ mode |= S_IWUSR;
+ return mode;
+}
+
static void init_feature_attrs(void)
{
int i;
@@ -115,6 +132,7 @@ static void init_feature_attrs(void)
attr = &btrfs_feature_attrs[fa->feature_set][n].attr;
attr->name = fa->attr.name;
+ attr->mode = fa_mode(fa);
btrfs_feature_names[fa->feature_set][n][0] = '\0';
}
@@ -132,6 +150,18 @@ static u64 get_features(struct btrfs_fs_
return btrfs_super_incompat_flags(disk_super);
}
+static void set_features(struct btrfs_fs_info *fs_info,
+ enum btrfs_feature_set set, u64 features)
+{
+ struct btrfs_super_block *disk_super = fs_info->super_copy;
+ if (set == FEAT_COMPAT)
+ btrfs_set_super_compat_flags(disk_super, features);
+ else if (set == FEAT_COMPAT_RO)
+ btrfs_set_super_compat_ro_flags(disk_super, features);
+ else
+ btrfs_set_super_incompat_flags(disk_super, features);
+}
+
#define feat_kobj_to_fs_info(kobj) \
container_of(kobj, struct btrfs_fs_info, features_kc.kc_kobj)
static ssize_t btrfs_feat_show(struct kobject *kobj, struct attribute *attr,
@@ -144,8 +174,72 @@ static ssize_t btrfs_feat_show(struct ko
return snprintf(buf, PAGE_SIZE, "%u\n", !!(features & fa->feature_bit));
}
+static ssize_t btrfs_feat_store(struct kobject *kobj, struct attribute *attr,
+ const char *buf, size_t count)
+{
+ struct btrfs_fs_info *fs_info = feat_kobj_to_fs_info(kobj);
+ struct btrfs_feature_attr *fa = to_btrfs_feature_attr(attr);
+ struct btrfs_trans_handle *trans;
+ u64 features, set, clear;
+ unsigned long val;
+ int ret;
+
+ ret = kstrtoul(skip_spaces(buf), 0, &val);
+ if (ret)
+ return ret;
+
+ if (fa->feature_set == FEAT_COMPAT) {
+ set = BTRFS_FEATURE_COMPAT_SAFE_SET;
+ clear = BTRFS_FEATURE_COMPAT_SAFE_CLEAR;
+ } else if (fa->feature_set == FEAT_COMPAT_RO) {
+ set = BTRFS_FEATURE_COMPAT_RO_SAFE_SET;
+ clear = BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR;
+ } else {
+ set = BTRFS_FEATURE_INCOMPAT_SAFE_SET;
+ clear = BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR;
+ }
+
+ features = get_features(fs_info, fa->feature_set);
+
+ /* Nothing to do */
+ if ((val && (features & fa->feature_bit)) ||
+ (!val && !(features & fa->feature_bit)))
+ return count;
+
+ if ((val && !(set & fa->feature_bit)) ||
+ (!val && !(clear & fa->feature_bit))) {
+ btrfs_info(fs_info,
+ "%sabling feature %s on mounted fs is not supported.",
+ val ? "En" : "Dis", fa->attr.name);
+ return -EPERM;
+ }
+
+ btrfs_info(fs_info, "%s %s feature flag",
+ val ? "Setting" : "Clearing", fa->attr.name);
+
+ trans = btrfs_start_transaction(fs_info->fs_root, 1);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+
+ spin_lock(&fs_info->super_lock);
+ features = get_features(fs_info, fa->feature_set);
+ if (val)
+ features |= fa->feature_bit;
+ else
+ features &= ~fa->feature_bit;
+ set_features(fs_info, fa->feature_set, features);
+ spin_unlock(&fs_info->super_lock);
+
+ ret = btrfs_commit_transaction(trans, fs_info->fs_root);
+ if (ret)
+ return ret;
+
+ return count;
+}
+
static const struct sysfs_ops btrfs_feat_attr_ops = {
.show = btrfs_feat_show,
+ .store = btrfs_feat_store,
};
static struct kobj_type btrfs_feat_ktype = {
@@ -199,7 +293,8 @@ static int add_per_fs_feature_set(struct
u64 features = get_features(fs_info, fa->feature_set);
int error;
- if (!(features & fa->feature_bit))
+ if (!(features & fa->feature_bit) &&
+ !(fa->attr.mode & S_IWUSR))
continue;
error = sysfs_create_file(&fs_info->features_kc.kc_kobj,
This patch adds the ability to change (set/clear) features while the file system is mounted. A bitmask is added for each feature set for the support to set and clear the bits. A message indicating which bit has been set or cleared is issued when it's been changed and also when permission or support for a particular bit has been denied. Since the the attributes can now be writable, we need to introduce another struct attribute to hold the different permissions. If neither set or clear is supported, the file will have 0444 permissions. If either set or clear is supported, the file will have 0644 permissions and the store handler will filter out the write based on the bitmask. Signed-off-by: Jeff Mahoney <jeffm@suse.com> --- fs/btrfs/sysfs.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 96 insertions(+), 1 deletion(-) -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html