Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 966 insertions, 0 deletions

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
new file mode 100644
index 000000000..afec808a7
--- /dev/null
+++ b/fs/btrfs/sysfs.c
@@ -0,0 +1,966 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ */
+
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/completion.h>
+#include <linux/kobject.h>
+#include <linux/bug.h>
+#include <linux/debugfs.h>
+#include <linux/sched/mm.h>
+
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "sysfs.h"
+#include "volumes.h"
+
+static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj);
+static inline struct btrfs_fs_devices *to_fs_devs(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 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);
+}
+
+static int can_modify_feature(struct btrfs_feature_attr *fa)
+{
+	int val = 0;
+	u64 set, clear;
+	switch (fa->feature_set) {
+	case FEAT_COMPAT:
+		set = BTRFS_FEATURE_COMPAT_SAFE_SET;
+		clear = BTRFS_FEATURE_COMPAT_SAFE_CLEAR;
+		break;
+	case FEAT_COMPAT_RO:
+		set = BTRFS_FEATURE_COMPAT_RO_SAFE_SET;
+		clear = BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR;
+		break;
+	case FEAT_INCOMPAT:
+		set = BTRFS_FEATURE_INCOMPAT_SAFE_SET;
+		clear = BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR;
+		break;
+	default:
+		pr_warn("btrfs: sysfs: unknown feature set %d\n",
+				fa->feature_set);
+		return 0;
+	}
+
+	if (set & fa->feature_bit)
+		val |= 1;
+	if (clear & fa->feature_bit)
+		val |= 2;
+
+	return val;
+}
+
+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);
+	struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
+	if (fs_info) {
+		u64 features = get_features(fs_info, fa->feature_set);
+		if (features & fa->feature_bit)
+			val = 1;
+	} else
+		val = can_modify_feature(fa);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+
+static ssize_t btrfs_feature_attr_store(struct kobject *kobj,
+					struct kobj_attribute *a,
+					const char *buf, size_t count)
+{
+	struct btrfs_fs_info *fs_info;
+	struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
+	u64 features, set, clear;
+	unsigned long val;
+	int ret;
+
+	fs_info = to_fs_info(kobj);
+	if (!fs_info)
+		return -EPERM;
+
+	if (sb_rdonly(fs_info->sb))
+		return -EROFS;
+
+	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->kobj_attr.attr.name);
+		return -EPERM;
+	}
+
+	btrfs_info(fs_info, "%s %s feature flag",
+		   val ? "Setting" : "Clearing", fa->kobj_attr.attr.name);
+
+	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);
+
+	/*
+	 * We don't want to do full transaction commit from inside sysfs
+	 */
+	btrfs_set_pending(fs_info, COMMIT);
+	wake_up_process(fs_info->transaction_kthread);
+
+	return count;
+}
+
+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 (can_modify_feature(fa))
+			mode |= S_IWUSR;
+		else 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_zstd, COMPRESS_ZSTD);
+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);
+BTRFS_FEAT_ATTR_INCOMPAT(no_holes, NO_HOLES);
+BTRFS_FEAT_ATTR_COMPAT_RO(free_space_tree, FREE_SPACE_TREE);
+
+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_zstd),
+	BTRFS_FEAT_ATTR_PTR(big_metadata),
+	BTRFS_FEAT_ATTR_PTR(extended_iref),
+	BTRFS_FEAT_ATTR_PTR(raid56),
+	BTRFS_FEAT_ATTR_PTR(skinny_metadata),
+	BTRFS_FEAT_ATTR_PTR(no_holes),
+	BTRFS_FEAT_ATTR_PTR(free_space_tree),
+	NULL
+};
+
+/*
+ * Features which depend on feature bits and may differ between each fs.
+ *
+ * /sys/fs/btrfs/features lists all available features of this kernel while
+ * /sys/fs/btrfs/UUID/features shows features of the fs which are enabled or
+ * can be changed online.
+ */
+static const struct attribute_group btrfs_feature_attr_group = {
+	.name = "features",
+	.is_visible = btrfs_feature_visible,
+	.attrs = btrfs_supported_feature_attrs,
+};
+
+static ssize_t rmdir_subvol_show(struct kobject *kobj,
+				 struct kobj_attribute *ka, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "0\n");
+}
+BTRFS_ATTR(static_feature, rmdir_subvol, rmdir_subvol_show);
+
+static struct attribute *btrfs_supported_static_feature_attrs[] = {
+	BTRFS_ATTR_PTR(static_feature, rmdir_subvol),
+	NULL
+};
+
+/*
+ * Features which only depend on kernel version.
+ *
+ * These are listed in /sys/fs/btrfs/features along with
+ * btrfs_feature_attr_group
+ */
+static const struct attribute_group btrfs_static_feature_attr_group = {
+	.name = "features",
+	.attrs = btrfs_supported_static_feature_attrs,
+};
+
+static ssize_t btrfs_show_u64(u64 *value_ptr, spinlock_t *lock, char *buf)
+{
+	u64 val;
+	if (lock)
+		spin_lock(lock);
+	val = *value_ptr;
+	if (lock)
+		spin_unlock(lock);
+	return snprintf(buf, PAGE_SIZE, "%llu\n", val);
+}
+
+static ssize_t global_rsv_size_show(struct kobject *kobj,
+				    struct kobj_attribute *ka, char *buf)
+{
+	struct btrfs_fs_info *fs_info = to_fs_info(kobj->parent);
+	struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
+	return btrfs_show_u64(&block_rsv->size, &block_rsv->lock, buf);
+}
+BTRFS_ATTR(allocation, global_rsv_size, global_rsv_size_show);
+
+static ssize_t global_rsv_reserved_show(struct kobject *kobj,
+					struct kobj_attribute *a, char *buf)
+{
+	struct btrfs_fs_info *fs_info = to_fs_info(kobj->parent);
+	struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
+	return btrfs_show_u64(&block_rsv->reserved, &block_rsv->lock, buf);
+}
+BTRFS_ATTR(allocation, global_rsv_reserved, global_rsv_reserved_show);
+
+#define to_space_info(_kobj) container_of(_kobj, struct btrfs_space_info, kobj)
+#define to_raid_kobj(_kobj) container_of(_kobj, struct raid_kobject, kobj)
+
+static ssize_t raid_bytes_show(struct kobject *kobj,
+			       struct kobj_attribute *attr, char *buf);
+BTRFS_ATTR(raid, total_bytes, raid_bytes_show);
+BTRFS_ATTR(raid, used_bytes, raid_bytes_show);
+
+static ssize_t raid_bytes_show(struct kobject *kobj,
+			       struct kobj_attribute *attr, char *buf)
+
+{
+	struct btrfs_space_info *sinfo = to_space_info(kobj->parent);
+	struct btrfs_block_group_cache *block_group;
+	int index = btrfs_bg_flags_to_raid_index(to_raid_kobj(kobj)->flags);
+	u64 val = 0;
+
+	down_read(&sinfo->groups_sem);
+	list_for_each_entry(block_group, &sinfo->block_groups[index], list) {
+		if (&attr->attr == BTRFS_ATTR_PTR(raid, total_bytes))
+			val += block_group->key.offset;
+		else
+			val += btrfs_block_group_used(&block_group->item);
+	}
+	up_read(&sinfo->groups_sem);
+	return snprintf(buf, PAGE_SIZE, "%llu\n", val);
+}
+
+static struct attribute *raid_attributes[] = {
+	BTRFS_ATTR_PTR(raid, total_bytes),
+	BTRFS_ATTR_PTR(raid, used_bytes),
+	NULL
+};
+
+static void release_raid_kobj(struct kobject *kobj)
+{
+	kfree(to_raid_kobj(kobj));
+}
+
+struct kobj_type btrfs_raid_ktype = {
+	.sysfs_ops = &kobj_sysfs_ops,
+	.release = release_raid_kobj,
+	.default_attrs = raid_attributes,
+};
+
+#define SPACE_INFO_ATTR(field)						\
+static ssize_t btrfs_space_info_show_##field(struct kobject *kobj,	\
+					     struct kobj_attribute *a,	\
+					     char *buf)			\
+{									\
+	struct btrfs_space_info *sinfo = to_space_info(kobj);		\
+	return btrfs_show_u64(&sinfo->field, &sinfo->lock, buf);	\
+}									\
+BTRFS_ATTR(space_info, field, btrfs_space_info_show_##field)
+
+static ssize_t btrfs_space_info_show_total_bytes_pinned(struct kobject *kobj,
+						       struct kobj_attribute *a,
+						       char *buf)
+{
+	struct btrfs_space_info *sinfo = to_space_info(kobj);
+	s64 val = percpu_counter_sum(&sinfo->total_bytes_pinned);
+	return snprintf(buf, PAGE_SIZE, "%lld\n", val);
+}
+
+SPACE_INFO_ATTR(flags);
+SPACE_INFO_ATTR(total_bytes);
+SPACE_INFO_ATTR(bytes_used);
+SPACE_INFO_ATTR(bytes_pinned);
+SPACE_INFO_ATTR(bytes_reserved);
+SPACE_INFO_ATTR(bytes_may_use);
+SPACE_INFO_ATTR(bytes_readonly);
+SPACE_INFO_ATTR(disk_used);
+SPACE_INFO_ATTR(disk_total);
+BTRFS_ATTR(space_info, total_bytes_pinned,
+	   btrfs_space_info_show_total_bytes_pinned);
+
+static struct attribute *space_info_attrs[] = {
+	BTRFS_ATTR_PTR(space_info, flags),
+	BTRFS_ATTR_PTR(space_info, total_bytes),
+	BTRFS_ATTR_PTR(space_info, bytes_used),
+	BTRFS_ATTR_PTR(space_info, bytes_pinned),
+	BTRFS_ATTR_PTR(space_info, bytes_reserved),
+	BTRFS_ATTR_PTR(space_info, bytes_may_use),
+	BTRFS_ATTR_PTR(space_info, bytes_readonly),
+	BTRFS_ATTR_PTR(space_info, disk_used),
+	BTRFS_ATTR_PTR(space_info, disk_total),
+	BTRFS_ATTR_PTR(space_info, total_bytes_pinned),
+	NULL,
+};
+
+static void space_info_release(struct kobject *kobj)
+{
+	struct btrfs_space_info *sinfo = to_space_info(kobj);
+	percpu_counter_destroy(&sinfo->total_bytes_pinned);
+	kfree(sinfo);
+}
+
+struct kobj_type space_info_ktype = {
+	.sysfs_ops = &kobj_sysfs_ops,
+	.release = space_info_release,
+	.default_attrs = space_info_attrs,
+};
+
+static const struct attribute *allocation_attrs[] = {
+	BTRFS_ATTR_PTR(allocation, global_rsv_reserved),
+	BTRFS_ATTR_PTR(allocation, global_rsv_size),
+	NULL,
+};
+
+static ssize_t btrfs_label_show(struct kobject *kobj,
+				struct kobj_attribute *a, char *buf)
+{
+	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+	char *label = fs_info->super_copy->label;
+	ssize_t ret;
+
+	spin_lock(&fs_info->super_lock);
+	ret = snprintf(buf, PAGE_SIZE, label[0] ? "%s\n" : "%s", label);
+	spin_unlock(&fs_info->super_lock);
+
+	return ret;
+}
+
+static ssize_t btrfs_label_store(struct kobject *kobj,
+				 struct kobj_attribute *a,
+				 const char *buf, size_t len)
+{
+	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+	size_t p_len;
+
+	if (!fs_info)
+		return -EPERM;
+
+	if (sb_rdonly(fs_info->sb))
+		return -EROFS;
+
+	/*
+	 * p_len is the len until the first occurrence of either
+	 * '\n' or '\0'
+	 */
+	p_len = strcspn(buf, "\n");
+
+	if (p_len >= BTRFS_LABEL_SIZE)
+		return -EINVAL;
+
+	spin_lock(&fs_info->super_lock);
+	memset(fs_info->super_copy->label, 0, BTRFS_LABEL_SIZE);
+	memcpy(fs_info->super_copy->label, buf, p_len);
+	spin_unlock(&fs_info->super_lock);
+
+	/*
+	 * We don't want to do full transaction commit from inside sysfs
+	 */
+	btrfs_set_pending(fs_info, COMMIT);
+	wake_up_process(fs_info->transaction_kthread);
+
+	return len;
+}
+BTRFS_ATTR_RW(, label, btrfs_label_show, btrfs_label_store);
+
+static ssize_t btrfs_nodesize_show(struct kobject *kobj,
+				struct kobj_attribute *a, char *buf)
+{
+	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->super_copy->nodesize);
+}
+
+BTRFS_ATTR(, nodesize, btrfs_nodesize_show);
+
+static ssize_t btrfs_sectorsize_show(struct kobject *kobj,
+				struct kobj_attribute *a, char *buf)
+{
+	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n",
+			fs_info->super_copy->sectorsize);
+}
+
+BTRFS_ATTR(, sectorsize, btrfs_sectorsize_show);
+
+static ssize_t btrfs_clone_alignment_show(struct kobject *kobj,
+				struct kobj_attribute *a, char *buf)
+{
+	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n",
+			fs_info->super_copy->sectorsize);
+}
+
+BTRFS_ATTR(, clone_alignment, btrfs_clone_alignment_show);
+
+static ssize_t quota_override_show(struct kobject *kobj,
+				   struct kobj_attribute *a, char *buf)
+{
+	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+	int quota_override;
+
+	quota_override = test_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);
+	return snprintf(buf, PAGE_SIZE, "%d\n", quota_override);
+}
+
+static ssize_t quota_override_store(struct kobject *kobj,
+				    struct kobj_attribute *a,
+				    const char *buf, size_t len)
+{
+	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+	unsigned long knob;
+	int err;
+
+	if (!fs_info)
+		return -EPERM;
+
+	if (!capable(CAP_SYS_RESOURCE))
+		return -EPERM;
+
+	err = kstrtoul(buf, 10, &knob);
+	if (err)
+		return err;
+	if (knob > 1)
+		return -EINVAL;
+
+	if (knob)
+		set_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);
+	else
+		clear_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);
+
+	return len;
+}
+
+BTRFS_ATTR_RW(, quota_override, quota_override_show, quota_override_store);
+
+static const struct attribute *btrfs_attrs[] = {
+	BTRFS_ATTR_PTR(, label),
+	BTRFS_ATTR_PTR(, nodesize),
+	BTRFS_ATTR_PTR(, sectorsize),
+	BTRFS_ATTR_PTR(, clone_alignment),
+	BTRFS_ATTR_PTR(, quota_override),
+	NULL,
+};
+
+static void btrfs_release_fsid_kobj(struct kobject *kobj)
+{
+	struct btrfs_fs_devices *fs_devs = to_fs_devs(kobj);
+
+	memset(&fs_devs->fsid_kobj, 0, sizeof(struct kobject));
+	complete(&fs_devs->kobj_unregister);
+}
+
+static struct kobj_type btrfs_ktype = {
+	.sysfs_ops	= &kobj_sysfs_ops,
+	.release	= btrfs_release_fsid_kobj,
+};
+
+static inline struct btrfs_fs_devices *to_fs_devs(struct kobject *kobj)
+{
+	if (kobj->ktype != &btrfs_ktype)
+		return NULL;
+	return container_of(kobj, struct btrfs_fs_devices, fsid_kobj);
+}
+
+static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)
+{
+	if (kobj->ktype != &btrfs_ktype)
+		return NULL;
+	return to_fs_devs(kobj)->fs_info;
+}
+
+#define NUM_FEATURE_BITS 64
+#define BTRFS_FEATURE_NAME_MAX 13
+static char btrfs_unknown_feature_names[FEAT_MAX][NUM_FEATURE_BITS][BTRFS_FEATURE_NAME_MAX];
+static struct btrfs_feature_attr btrfs_feature_attrs[FEAT_MAX][NUM_FEATURE_BITS];
+
+static const u64 supported_feature_masks[FEAT_MAX] = {
+	[FEAT_COMPAT]    = BTRFS_FEATURE_COMPAT_SUPP,
+	[FEAT_COMPAT_RO] = BTRFS_FEATURE_COMPAT_RO_SUPP,
+	[FEAT_INCOMPAT]  = BTRFS_FEATURE_INCOMPAT_SUPP,
+};
+
+static int addrm_unknown_feature_attrs(struct btrfs_fs_info *fs_info, bool add)
+{
+	int set;
+
+	for (set = 0; set < FEAT_MAX; set++) {
+		int i;
+		struct attribute *attrs[2];
+		struct attribute_group agroup = {
+			.name = "features",
+			.attrs = attrs,
+		};
+		u64 features = get_features(fs_info, set);
+		features &= ~supported_feature_masks[set];
+
+		if (!features)
+			continue;
+
+		attrs[1] = NULL;
+		for (i = 0; i < NUM_FEATURE_BITS; i++) {
+			struct btrfs_feature_attr *fa;
+
+			if (!(features & (1ULL << i)))
+				continue;
+
+			fa = &btrfs_feature_attrs[set][i];
+			attrs[0] = &fa->kobj_attr.attr;
+			if (add) {
+				int ret;
+				ret = sysfs_merge_group(&fs_info->fs_devices->fsid_kobj,
+							&agroup);
+				if (ret)
+					return ret;
+			} else
+				sysfs_unmerge_group(&fs_info->fs_devices->fsid_kobj,
+						    &agroup);
+		}
+
+	}
+	return 0;
+}
+
+static void __btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
+{
+	if (fs_devs->device_dir_kobj) {
+		kobject_del(fs_devs->device_dir_kobj);
+		kobject_put(fs_devs->device_dir_kobj);
+		fs_devs->device_dir_kobj = NULL;
+	}
+
+	if (fs_devs->fsid_kobj.state_initialized) {
+		kobject_del(&fs_devs->fsid_kobj);
+		kobject_put(&fs_devs->fsid_kobj);
+		wait_for_completion(&fs_devs->kobj_unregister);
+	}
+}
+
+/* when fs_devs is NULL it will remove all fsid kobject */
+void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
+{
+	struct list_head *fs_uuids = btrfs_get_fs_uuids();
+
+	if (fs_devs) {
+		__btrfs_sysfs_remove_fsid(fs_devs);
+		return;
+	}
+
+	list_for_each_entry(fs_devs, fs_uuids, fs_list) {
+		__btrfs_sysfs_remove_fsid(fs_devs);
+	}
+}
+
+void btrfs_sysfs_remove_mounted(struct btrfs_fs_info *fs_info)
+{
+	btrfs_reset_fs_info_ptr(fs_info);
+
+	if (fs_info->space_info_kobj) {
+		sysfs_remove_files(fs_info->space_info_kobj, allocation_attrs);
+		kobject_del(fs_info->space_info_kobj);
+		kobject_put(fs_info->space_info_kobj);
+	}
+	addrm_unknown_feature_attrs(fs_info, false);
+	sysfs_remove_group(&fs_info->fs_devices->fsid_kobj, &btrfs_feature_attr_group);
+	sysfs_remove_files(&fs_info->fs_devices->fsid_kobj, btrfs_attrs);
+	btrfs_sysfs_rm_device_link(fs_info->fs_devices, NULL);
+}
+
+const char * const btrfs_feature_set_names[FEAT_MAX] = {
+	[FEAT_COMPAT]	 = "compat",
+	[FEAT_COMPAT_RO] = "compat_ro",
+	[FEAT_INCOMPAT]	 = "incompat",
+};
+
+char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags)
+{
+	size_t bufsize = 4096; /* safe max, 64 names * 64 bytes */
+	int len = 0;
+	int i;
+	char *str;
+
+	str = kmalloc(bufsize, GFP_KERNEL);
+	if (!str)
+		return str;
+
+	for (i = 0; i < ARRAY_SIZE(btrfs_feature_attrs[set]); i++) {
+		const char *name;
+
+		if (!(flags & (1ULL << i)))
+			continue;
+
+		name = btrfs_feature_attrs[set][i].kobj_attr.attr.name;
+		len += snprintf(str + len, bufsize - len, "%s%s",
+				len ? "," : "", name);
+	}
+
+	return str;
+}
+
+static void init_feature_attrs(void)
+{
+	struct btrfs_feature_attr *fa;
+	int set, i;
+
+	BUILD_BUG_ON(ARRAY_SIZE(btrfs_unknown_feature_names) !=
+		     ARRAY_SIZE(btrfs_feature_attrs));
+	BUILD_BUG_ON(ARRAY_SIZE(btrfs_unknown_feature_names[0]) !=
+		     ARRAY_SIZE(btrfs_feature_attrs[0]));
+
+	memset(btrfs_feature_attrs, 0, sizeof(btrfs_feature_attrs));
+	memset(btrfs_unknown_feature_names, 0,
+	       sizeof(btrfs_unknown_feature_names));
+
+	for (i = 0; btrfs_supported_feature_attrs[i]; i++) {
+		struct btrfs_feature_attr *sfa;
+		struct attribute *a = btrfs_supported_feature_attrs[i];
+		int bit;
+		sfa = attr_to_btrfs_feature_attr(a);
+		bit = ilog2(sfa->feature_bit);
+		fa = &btrfs_feature_attrs[sfa->feature_set][bit];
+
+		fa->kobj_attr.attr.name = sfa->kobj_attr.attr.name;
+	}
+
+	for (set = 0; set < FEAT_MAX; set++) {
+		for (i = 0; i < ARRAY_SIZE(btrfs_feature_attrs[set]); i++) {
+			char *name = btrfs_unknown_feature_names[set][i];
+			fa = &btrfs_feature_attrs[set][i];
+
+			if (fa->kobj_attr.attr.name)
+				continue;
+
+			snprintf(name, BTRFS_FEATURE_NAME_MAX, "%s:%u",
+				 btrfs_feature_set_names[set], i);
+
+			fa->kobj_attr.attr.name = name;
+			fa->kobj_attr.attr.mode = S_IRUGO;
+			fa->feature_set = set;
+			fa->feature_bit = 1ULL << i;
+		}
+	}
+}
+
+/* when one_device is NULL, it removes all device links */
+
+int btrfs_sysfs_rm_device_link(struct btrfs_fs_devices *fs_devices,
+		struct btrfs_device *one_device)
+{
+	struct hd_struct *disk;
+	struct kobject *disk_kobj;
+
+	if (!fs_devices->device_dir_kobj)
+		return -EINVAL;
+
+	if (one_device && one_device->bdev) {
+		disk = one_device->bdev->bd_part;
+		disk_kobj = &part_to_dev(disk)->kobj;
+
+		sysfs_remove_link(fs_devices->device_dir_kobj,
+						disk_kobj->name);
+	}
+
+	if (one_device)
+		return 0;
+
+	list_for_each_entry(one_device,
+			&fs_devices->devices, dev_list) {
+		if (!one_device->bdev)
+			continue;
+		disk = one_device->bdev->bd_part;
+		disk_kobj = &part_to_dev(disk)->kobj;
+
+		sysfs_remove_link(fs_devices->device_dir_kobj,
+						disk_kobj->name);
+	}
+
+	return 0;
+}
+
+int btrfs_sysfs_add_device(struct btrfs_fs_devices *fs_devs)
+{
+	if (!fs_devs->device_dir_kobj)
+		fs_devs->device_dir_kobj = kobject_create_and_add("devices",
+						&fs_devs->fsid_kobj);
+
+	if (!fs_devs->device_dir_kobj)
+		return -ENOMEM;
+
+	return 0;
+}
+
+int btrfs_sysfs_add_device_link(struct btrfs_fs_devices *fs_devices,
+				struct btrfs_device *one_device)
+{
+	int error = 0;
+	struct btrfs_device *dev;
+	unsigned int nofs_flag;
+
+	nofs_flag = memalloc_nofs_save();
+	list_for_each_entry(dev, &fs_devices->devices, dev_list) {
+		struct hd_struct *disk;
+		struct kobject *disk_kobj;
+
+		if (!dev->bdev)
+			continue;
+
+		if (one_device && one_device != dev)
+			continue;
+
+		disk = dev->bdev->bd_part;
+		disk_kobj = &part_to_dev(disk)->kobj;
+
+		error = sysfs_create_link(fs_devices->device_dir_kobj,
+					  disk_kobj, disk_kobj->name);
+		if (error)
+			break;
+	}
+	memalloc_nofs_restore(nofs_flag);
+
+	return error;
+}
+
+/* /sys/fs/btrfs/ entry */
+static struct kset *btrfs_kset;
+
+/* /sys/kernel/debug/btrfs */
+static struct dentry *btrfs_debugfs_root_dentry;
+
+/* Debugging tunables and exported data */
+u64 btrfs_debugfs_test;
+
+/*
+ * Can be called by the device discovery thread.
+ * And parent can be specified for seed device
+ */
+int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
+				struct kobject *parent)
+{
+	int error;
+
+	init_completion(&fs_devs->kobj_unregister);
+	fs_devs->fsid_kobj.kset = btrfs_kset;
+	error = kobject_init_and_add(&fs_devs->fsid_kobj,
+				&btrfs_ktype, parent, "%pU", fs_devs->fsid);
+	if (error) {
+		kobject_put(&fs_devs->fsid_kobj);
+		return error;
+	}
+
+	return 0;
+}
+
+int btrfs_sysfs_add_mounted(struct btrfs_fs_info *fs_info)
+{
+	int error;
+	struct btrfs_fs_devices *fs_devs = fs_info->fs_devices;
+	struct kobject *fsid_kobj = &fs_devs->fsid_kobj;
+
+	btrfs_set_fs_info_ptr(fs_info);
+
+	error = btrfs_sysfs_add_device_link(fs_devs, NULL);
+	if (error)
+		return error;
+
+	error = sysfs_create_files(fsid_kobj, btrfs_attrs);
+	if (error) {
+		btrfs_sysfs_rm_device_link(fs_devs, NULL);
+		return error;
+	}
+
+	error = sysfs_create_group(fsid_kobj,
+				   &btrfs_feature_attr_group);
+	if (error)
+		goto failure;
+
+	error = addrm_unknown_feature_attrs(fs_info, true);
+	if (error)
+		goto failure;
+
+	fs_info->space_info_kobj = kobject_create_and_add("allocation",
+						  fsid_kobj);
+	if (!fs_info->space_info_kobj) {
+		error = -ENOMEM;
+		goto failure;
+	}
+
+	error = sysfs_create_files(fs_info->space_info_kobj, allocation_attrs);
+	if (error)
+		goto failure;
+
+	return 0;
+failure:
+	btrfs_sysfs_remove_mounted(fs_info);
+	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;
+
+	if (!fsid_kobj->state_initialized)
+		return;
+
+	/*
+	 * 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
+	btrfs_debugfs_root_dentry = debugfs_create_dir("btrfs", NULL);
+	if (!btrfs_debugfs_root_dentry)
+		return -ENOMEM;
+
+	/*
+	 * Example code, how to export data through debugfs.
+	 *
+	 * file:        /sys/kernel/debug/btrfs/test
+	 * contents of: btrfs_debugfs_test
+	 */
+#ifdef CONFIG_BTRFS_DEBUG
+	debugfs_create_u64("test", S_IRUGO | S_IWUSR, btrfs_debugfs_root_dentry,
+			&btrfs_debugfs_test);
+#endif
+
+#endif
+	return 0;
+}
+
+int __init btrfs_init_sysfs(void)
+{
+	int ret;
+
+	btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj);
+	if (!btrfs_kset)
+		return -ENOMEM;
+
+	ret = btrfs_init_debugfs();
+	if (ret)
+		goto out1;
+
+	init_feature_attrs();
+	ret = sysfs_create_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
+	if (ret)
+		goto out2;
+	ret = sysfs_merge_group(&btrfs_kset->kobj,
+				&btrfs_static_feature_attr_group);
+	if (ret)
+		goto out_remove_group;
+
+	return 0;
+
+out_remove_group:
+	sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
+out2:
+	debugfs_remove_recursive(btrfs_debugfs_root_dentry);
+out1:
+	kset_unregister(btrfs_kset);
+
+	return ret;
+}
+
+void __cold btrfs_exit_sysfs(void)
+{
+	sysfs_unmerge_group(&btrfs_kset->kobj,
+			    &btrfs_static_feature_attr_group);
+	sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
+	kset_unregister(btrfs_kset);
+	debugfs_remove_recursive(btrfs_debugfs_root_dentry);
+}
+