root/fs/btrfs/sysfs.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 */

#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/bug.h>
#include <linux/list.h>
#include <linux/string_choices.h>
#include "messages.h"
#include "ctree.h"
#include "discard.h"
#include "disk-io.h"
#include "send.h"
#include "transaction.h"
#include "sysfs.h"
#include "volumes.h"
#include "space-info.h"
#include "block-group.h"
#include "qgroup.h"
#include "misc.h"
#include "fs.h"
#include "accessors.h"

/*
 * Structure name                       Path
 * --------------------------------------------------------------------------
 * btrfs_supported_static_feature_attrs /sys/fs/btrfs/features
 * btrfs_supported_feature_attrs        /sys/fs/btrfs/features and
 *                                      /sys/fs/btrfs/<uuid>/features
 * btrfs_attrs                          /sys/fs/btrfs/<uuid>
 * devid_attrs                          /sys/fs/btrfs/<uuid>/devinfo/<devid>
 * allocation_attrs                     /sys/fs/btrfs/<uuid>/allocation
 * qgroup_attrs                         /sys/fs/btrfs/<uuid>/qgroups/<level>_<qgroupid>
 * space_info_attrs                     /sys/fs/btrfs/<uuid>/allocation/<bg-type>
 * raid_attrs                           /sys/fs/btrfs/<uuid>/allocation/<bg-type>/<bg-profile>
 * discard_attrs                        /sys/fs/btrfs/<uuid>/discard
 *
 * When built with BTRFS_CONFIG_DEBUG:
 *
 * btrfs_debug_feature_attrs            /sys/fs/btrfs/debug
 * btrfs_debug_mount_attrs              /sys/fs/btrfs/<uuid>/debug
 */

struct btrfs_feature_attr {
        struct kobj_attribute kobj_attr;
        enum btrfs_feature_set feature_set;
        u64 feature_bit;
};

/* For raid type sysfs entries */
struct raid_kobject {
        u64 flags;
        struct kobject kobj;
};

#define __INIT_KOBJ_ATTR(_name, _mode, _show, _store)                   \
{                                                                       \
        .attr   = { .name = __stringify(_name), .mode = _mode },        \
        .show   = _show,                                                \
        .store  = _store,                                               \
}

#define BTRFS_ATTR_W(_prefix, _name, _store)                            \
        static struct kobj_attribute btrfs_attr_##_prefix##_##_name =   \
                        __INIT_KOBJ_ATTR(_name, 0200, NULL, _store)

#define BTRFS_ATTR_RW(_prefix, _name, _show, _store)                    \
        static struct kobj_attribute btrfs_attr_##_prefix##_##_name =   \
                        __INIT_KOBJ_ATTR(_name, 0644, _show, _store)

#define BTRFS_ATTR(_prefix, _name, _show)                               \
        static struct kobj_attribute btrfs_attr_##_prefix##_##_name =   \
                        __INIT_KOBJ_ATTR(_name, 0444, _show, NULL)

#define BTRFS_ATTR_PTR(_prefix, _name)                                  \
        (&btrfs_attr_##_prefix##_##_name.attr)

#define BTRFS_FEAT_ATTR(_name, _feature_set, _feature_prefix, _feature_bit)  \
static struct btrfs_feature_attr btrfs_attr_features_##_name = {             \
        .kobj_attr = __INIT_KOBJ_ATTR(_name, S_IRUGO,                        \
                                      btrfs_feature_attr_show,               \
                                      btrfs_feature_attr_store),             \
        .feature_set    = _feature_set,                                      \
        .feature_bit    = _feature_prefix ##_## _feature_bit,                \
}
#define BTRFS_FEAT_ATTR_PTR(_name)                                           \
        (&btrfs_attr_features_##_name.kobj_attr.attr)

#define BTRFS_FEAT_ATTR_COMPAT(name, feature) \
        BTRFS_FEAT_ATTR(name, FEAT_COMPAT, BTRFS_FEATURE_COMPAT, feature)
#define BTRFS_FEAT_ATTR_COMPAT_RO(name, feature) \
        BTRFS_FEAT_ATTR(name, FEAT_COMPAT_RO, BTRFS_FEATURE_COMPAT_RO, feature)
#define BTRFS_FEAT_ATTR_INCOMPAT(name, feature) \
        BTRFS_FEAT_ATTR(name, FEAT_INCOMPAT, BTRFS_FEATURE_INCOMPAT, feature)

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 struct kobject *get_btrfs_kobj(struct kobject *kobj);

static struct btrfs_feature_attr *to_btrfs_feature_attr(struct kobj_attribute *a)
{
        return container_of(a, struct btrfs_feature_attr, kobj_attr);
}

static struct kobj_attribute *attr_to_btrfs_attr(struct attribute *attr)
{
        return container_of(attr, struct kobj_attribute, attr);
}

static struct btrfs_feature_attr *attr_to_btrfs_feature_attr(
                struct attribute *attr)
{
        return to_btrfs_feature_attr(attr_to_btrfs_attr(attr));
}

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:
                btrfs_warn(NULL, "sysfs: unknown feature set %d", 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 sysfs_emit(buf, "%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
         */
        set_bit(BTRFS_FS_NEED_TRANS_COMMIT, &fs_info->flags);
        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(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(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_INCOMPAT(metadata_uuid, METADATA_UUID);
BTRFS_FEAT_ATTR_COMPAT_RO(free_space_tree, FREE_SPACE_TREE);
BTRFS_FEAT_ATTR_COMPAT_RO(block_group_tree, BLOCK_GROUP_TREE);
BTRFS_FEAT_ATTR_INCOMPAT(raid1c34, RAID1C34);
BTRFS_FEAT_ATTR_INCOMPAT(simple_quota, SIMPLE_QUOTA);
#ifdef CONFIG_BLK_DEV_ZONED
BTRFS_FEAT_ATTR_INCOMPAT(zoned, ZONED);
#endif
#ifdef CONFIG_BTRFS_EXPERIMENTAL
/* Remove once support for extent tree v2 is feature complete */
BTRFS_FEAT_ATTR_INCOMPAT(extent_tree_v2, EXTENT_TREE_V2);
/* Remove once support for raid stripe tree is feature complete. */
BTRFS_FEAT_ATTR_INCOMPAT(raid_stripe_tree, RAID_STRIPE_TREE);
/* Remove once support for remap tree is feature complete. */
BTRFS_FEAT_ATTR_INCOMPAT(remap_tree, REMAP_TREE);
#endif
#ifdef CONFIG_FS_VERITY
BTRFS_FEAT_ATTR_COMPAT_RO(verity, VERITY);
#endif

/*
 * Features which depend on feature bits and may differ between each fs.
 *
 * /sys/fs/btrfs/features      - all available features implemented by this version
 * /sys/fs/btrfs/UUID/features - features of the fs which are enabled or
 *                               can be changed on a mounted filesystem.
 */
static struct attribute *btrfs_supported_feature_attrs[] = {
        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(extended_iref),
        BTRFS_FEAT_ATTR_PTR(raid56),
        BTRFS_FEAT_ATTR_PTR(skinny_metadata),
        BTRFS_FEAT_ATTR_PTR(no_holes),
        BTRFS_FEAT_ATTR_PTR(metadata_uuid),
        BTRFS_FEAT_ATTR_PTR(free_space_tree),
        BTRFS_FEAT_ATTR_PTR(raid1c34),
        BTRFS_FEAT_ATTR_PTR(block_group_tree),
        BTRFS_FEAT_ATTR_PTR(simple_quota),
#ifdef CONFIG_BLK_DEV_ZONED
        BTRFS_FEAT_ATTR_PTR(zoned),
#endif
#ifdef CONFIG_BTRFS_EXPERIMENTAL
        BTRFS_FEAT_ATTR_PTR(extent_tree_v2),
        BTRFS_FEAT_ATTR_PTR(raid_stripe_tree),
        BTRFS_FEAT_ATTR_PTR(remap_tree),
#endif
#ifdef CONFIG_FS_VERITY
        BTRFS_FEAT_ATTR_PTR(verity),
#endif
        NULL
};

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 sysfs_emit(buf, "0\n");
}
BTRFS_ATTR(static_feature, rmdir_subvol, rmdir_subvol_show);

static ssize_t supported_checksums_show(struct kobject *kobj,
                                        struct kobj_attribute *a, char *buf)
{
        ssize_t ret = 0;
        int i;

        for (i = 0; i < btrfs_get_num_csums(); i++) {
                /*
                 * This "trick" only works as long as 'enum btrfs_csum_type' has
                 * no holes in it
                 */
                ret += sysfs_emit_at(buf, ret, "%s%s", (i == 0 ? "" : " "),
                                     btrfs_super_csum_name(i));

        }

        ret += sysfs_emit_at(buf, ret, "\n");
        return ret;
}
BTRFS_ATTR(static_feature, supported_checksums, supported_checksums_show);

static ssize_t send_stream_version_show(struct kobject *kobj,
                                        struct kobj_attribute *ka, char *buf)
{
        return sysfs_emit(buf, "%d\n", BTRFS_SEND_STREAM_VERSION);
}
BTRFS_ATTR(static_feature, send_stream_version, send_stream_version_show);

static const char *rescue_opts[] = {
        "usebackuproot",
        "nologreplay",
        "ignorebadroots",
        "ignoredatacsums",
        "ignoremetacsums",
        "ignoresuperflags",
        "all",
};

static ssize_t supported_rescue_options_show(struct kobject *kobj,
                                             struct kobj_attribute *a,
                                             char *buf)
{
        ssize_t ret = 0;
        int i;

        for (i = 0; i < ARRAY_SIZE(rescue_opts); i++)
                ret += sysfs_emit_at(buf, ret, "%s%s", (i ? " " : ""), rescue_opts[i]);
        ret += sysfs_emit_at(buf, ret, "\n");
        return ret;
}
BTRFS_ATTR(static_feature, supported_rescue_options,
           supported_rescue_options_show);

static ssize_t supported_sectorsizes_show(struct kobject *kobj,
                                          struct kobj_attribute *a,
                                          char *buf)
{
        ssize_t ret = 0;
        bool has_output = false;

        for (u32 cur = BTRFS_MIN_BLOCKSIZE; cur <= BTRFS_MAX_BLOCKSIZE; cur *= 2) {
                if (!btrfs_supported_blocksize(cur))
                        continue;
                if (has_output)
                        ret += sysfs_emit_at(buf, ret, " ");
                ret += sysfs_emit_at(buf, ret, "%u", cur);
                has_output = true;
        }
        ret += sysfs_emit_at(buf, ret, "\n");
        return ret;
}
BTRFS_ATTR(static_feature, supported_sectorsizes,
           supported_sectorsizes_show);

static ssize_t acl_show(struct kobject *kobj, struct kobj_attribute *a, char *buf)
{
        return sysfs_emit(buf, "%d\n", IS_ENABLED(CONFIG_BTRFS_FS_POSIX_ACL));
}
BTRFS_ATTR(static_feature, acl, acl_show);

static ssize_t temp_fsid_supported_show(struct kobject *kobj,
                                        struct kobj_attribute *a, char *buf)
{
        return sysfs_emit(buf, "0\n");
}
BTRFS_ATTR(static_feature, temp_fsid, temp_fsid_supported_show);

/*
 * Features which only depend on kernel version.
 *
 * These are listed in /sys/fs/btrfs/features along with
 * btrfs_supported_feature_attrs.
 */
static struct attribute *btrfs_supported_static_feature_attrs[] = {
        BTRFS_ATTR_PTR(static_feature, acl),
        BTRFS_ATTR_PTR(static_feature, rmdir_subvol),
        BTRFS_ATTR_PTR(static_feature, supported_checksums),
        BTRFS_ATTR_PTR(static_feature, send_stream_version),
        BTRFS_ATTR_PTR(static_feature, supported_rescue_options),
        BTRFS_ATTR_PTR(static_feature, supported_sectorsizes),
        BTRFS_ATTR_PTR(static_feature, temp_fsid),
        NULL
};

static const struct attribute_group btrfs_static_feature_attr_group = {
        .name = "features",
        .attrs = btrfs_supported_static_feature_attrs,
};

/*
 * Discard statistics and tunables
 */
#define discard_to_fs_info(_kobj)       to_fs_info(get_btrfs_kobj(_kobj))

static ssize_t btrfs_discardable_bytes_show(struct kobject *kobj,
                                            struct kobj_attribute *a,
                                            char *buf)
{
        struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);

        return sysfs_emit(buf, "%lld\n",
                        atomic64_read(&fs_info->discard_ctl.discardable_bytes));
}
BTRFS_ATTR(discard, discardable_bytes, btrfs_discardable_bytes_show);

static ssize_t btrfs_discardable_extents_show(struct kobject *kobj,
                                              struct kobj_attribute *a,
                                              char *buf)
{
        struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);

        return sysfs_emit(buf, "%d\n",
                        atomic_read(&fs_info->discard_ctl.discardable_extents));
}
BTRFS_ATTR(discard, discardable_extents, btrfs_discardable_extents_show);

static ssize_t btrfs_discard_bitmap_bytes_show(struct kobject *kobj,
                                               struct kobj_attribute *a,
                                               char *buf)
{
        struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);

        return sysfs_emit(buf, "%llu\n",
                          fs_info->discard_ctl.discard_bitmap_bytes);
}
BTRFS_ATTR(discard, discard_bitmap_bytes, btrfs_discard_bitmap_bytes_show);

static ssize_t btrfs_discard_bytes_saved_show(struct kobject *kobj,
                                              struct kobj_attribute *a,
                                              char *buf)
{
        struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);

        return sysfs_emit(buf, "%lld\n",
                atomic64_read(&fs_info->discard_ctl.discard_bytes_saved));
}
BTRFS_ATTR(discard, discard_bytes_saved, btrfs_discard_bytes_saved_show);

static ssize_t btrfs_discard_extent_bytes_show(struct kobject *kobj,
                                               struct kobj_attribute *a,
                                               char *buf)
{
        struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);

        return sysfs_emit(buf, "%llu\n",
                          fs_info->discard_ctl.discard_extent_bytes);
}
BTRFS_ATTR(discard, discard_extent_bytes, btrfs_discard_extent_bytes_show);

static ssize_t btrfs_discard_iops_limit_show(struct kobject *kobj,
                                             struct kobj_attribute *a,
                                             char *buf)
{
        struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);

        return sysfs_emit(buf, "%u\n",
                          READ_ONCE(fs_info->discard_ctl.iops_limit));
}

static ssize_t btrfs_discard_iops_limit_store(struct kobject *kobj,
                                              struct kobj_attribute *a,
                                              const char *buf, size_t len)
{
        struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
        struct btrfs_discard_ctl *discard_ctl = &fs_info->discard_ctl;
        u32 iops_limit;
        int ret;

        ret = kstrtou32(buf, 10, &iops_limit);
        if (ret)
                return -EINVAL;

        WRITE_ONCE(discard_ctl->iops_limit, iops_limit);
        btrfs_discard_calc_delay(discard_ctl);
        btrfs_discard_schedule_work(discard_ctl, true);
        return len;
}
BTRFS_ATTR_RW(discard, iops_limit, btrfs_discard_iops_limit_show,
              btrfs_discard_iops_limit_store);

static ssize_t btrfs_discard_kbps_limit_show(struct kobject *kobj,
                                             struct kobj_attribute *a,
                                             char *buf)
{
        struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);

        return sysfs_emit(buf, "%u\n",
                          READ_ONCE(fs_info->discard_ctl.kbps_limit));
}

static ssize_t btrfs_discard_kbps_limit_store(struct kobject *kobj,
                                              struct kobj_attribute *a,
                                              const char *buf, size_t len)
{
        struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
        struct btrfs_discard_ctl *discard_ctl = &fs_info->discard_ctl;
        u32 kbps_limit;
        int ret;

        ret = kstrtou32(buf, 10, &kbps_limit);
        if (ret)
                return -EINVAL;

        WRITE_ONCE(discard_ctl->kbps_limit, kbps_limit);
        btrfs_discard_schedule_work(discard_ctl, true);
        return len;
}
BTRFS_ATTR_RW(discard, kbps_limit, btrfs_discard_kbps_limit_show,
              btrfs_discard_kbps_limit_store);

static ssize_t btrfs_discard_max_discard_size_show(struct kobject *kobj,
                                                   struct kobj_attribute *a,
                                                   char *buf)
{
        struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);

        return sysfs_emit(buf, "%llu\n",
                          READ_ONCE(fs_info->discard_ctl.max_discard_size));
}

static ssize_t btrfs_discard_max_discard_size_store(struct kobject *kobj,
                                                    struct kobj_attribute *a,
                                                    const char *buf, size_t len)
{
        struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
        struct btrfs_discard_ctl *discard_ctl = &fs_info->discard_ctl;
        u64 max_discard_size;
        int ret;

        ret = kstrtou64(buf, 10, &max_discard_size);
        if (ret)
                return -EINVAL;

        WRITE_ONCE(discard_ctl->max_discard_size, max_discard_size);

        return len;
}
BTRFS_ATTR_RW(discard, max_discard_size, btrfs_discard_max_discard_size_show,
              btrfs_discard_max_discard_size_store);

/*
 * Per-filesystem stats for discard (when mounted with discard=async).
 *
 * Path: /sys/fs/btrfs/<uuid>/discard/
 */
static const struct attribute *discard_attrs[] = {
        BTRFS_ATTR_PTR(discard, discardable_bytes),
        BTRFS_ATTR_PTR(discard, discardable_extents),
        BTRFS_ATTR_PTR(discard, discard_bitmap_bytes),
        BTRFS_ATTR_PTR(discard, discard_bytes_saved),
        BTRFS_ATTR_PTR(discard, discard_extent_bytes),
        BTRFS_ATTR_PTR(discard, iops_limit),
        BTRFS_ATTR_PTR(discard, kbps_limit),
        BTRFS_ATTR_PTR(discard, max_discard_size),
        NULL,
};

#ifdef CONFIG_BTRFS_DEBUG

/*
 * Per-filesystem runtime debugging exported via sysfs.
 *
 * Path: /sys/fs/btrfs/UUID/debug/
 */
static const struct attribute *btrfs_debug_mount_attrs[] = {
        NULL,
};

/*
 * Runtime debugging exported via sysfs, applies to all mounted filesystems.
 *
 * Path: /sys/fs/btrfs/debug
 */
static struct attribute *btrfs_debug_feature_attrs[] = {
        NULL
};

static const struct attribute_group btrfs_debug_feature_attr_group = {
        .name = "debug",
        .attrs = btrfs_debug_feature_attrs,
};

#endif

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 sysfs_emit(buf, "%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 *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->length;
                else
                        val += block_group->used;
        }
        up_read(&sinfo->groups_sem);
        return sysfs_emit(buf, "%llu\n", val);
}

/*
 * Allocation information about block group profiles.
 *
 * Path: /sys/fs/btrfs/<uuid>/allocation/<bg-type>/<bg-profile>/
 */
static struct attribute *raid_attrs[] = {
        BTRFS_ATTR_PTR(raid, total_bytes),
        BTRFS_ATTR_PTR(raid, used_bytes),
        NULL
};
ATTRIBUTE_GROUPS(raid);

static void release_raid_kobj(struct kobject *kobj)
{
        kfree(to_raid_kobj(kobj));
}

static const struct kobj_type btrfs_raid_ktype = {
        .sysfs_ops = &kobj_sysfs_ops,
        .release = release_raid_kobj,
        .default_groups = raid_groups,
};

#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_chunk_size_show(struct kobject *kobj,
                                     struct kobj_attribute *a, char *buf)
{
        struct btrfs_space_info *sinfo = to_space_info(kobj);

        return sysfs_emit(buf, "%llu\n", READ_ONCE(sinfo->chunk_size));
}

/*
 * Store new chunk size in space info. Can be called on a read-only filesystem.
 *
 * If the new chunk size value is larger than 10% of free space it is reduced
 * to match that limit. Alignment must be to 256M and the system chunk size
 * cannot be set.
 */
static ssize_t btrfs_chunk_size_store(struct kobject *kobj,
                                      struct kobj_attribute *a,
                                      const char *buf, size_t len)
{
        struct btrfs_space_info *space_info = to_space_info(kobj);
        struct btrfs_fs_info *fs_info = to_fs_info(get_btrfs_kobj(kobj));
        char *retptr;
        u64 val;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (!fs_info->fs_devices)
                return -EINVAL;

        if (btrfs_is_zoned(fs_info))
                return -EINVAL;

        /* System block type must not be changed. */
        if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
                return -EPERM;

        val = memparse(buf, &retptr);
        /* There could be trailing '\n', also catch any typos after the value */
        retptr = skip_spaces(retptr);
        if (*retptr != 0 || val == 0)
                return -EINVAL;

        val = min(val, BTRFS_MAX_DATA_CHUNK_SIZE);

        /* Limit stripe size to 10% of available space. */
        val = min(mult_perc(fs_info->fs_devices->total_rw_bytes, 10), val);

        /* Must be multiple of 256M. */
        val &= ~((u64)SZ_256M - 1);

        /* Must be at least 256M. */
        if (val < SZ_256M)
                return -EINVAL;

        btrfs_update_space_info_chunk_size(space_info, val);

        return len;
}

static ssize_t btrfs_size_classes_show(struct kobject *kobj,
                                       struct kobj_attribute *a, char *buf)
{
        struct btrfs_space_info *sinfo = to_space_info(kobj);
        struct btrfs_block_group *bg;
        u32 none = 0;
        u32 small = 0;
        u32 medium = 0;
        u32 large = 0;

        for (int i = 0; i < BTRFS_NR_RAID_TYPES; ++i) {
                down_read(&sinfo->groups_sem);
                list_for_each_entry(bg, &sinfo->block_groups[i], list) {
                        if (!btrfs_block_group_should_use_size_class(bg))
                                continue;
                        switch (bg->size_class) {
                        case BTRFS_BG_SZ_NONE:
                                none++;
                                break;
                        case BTRFS_BG_SZ_SMALL:
                                small++;
                                break;
                        case BTRFS_BG_SZ_MEDIUM:
                                medium++;
                                break;
                        case BTRFS_BG_SZ_LARGE:
                                large++;
                                break;
                        }
                }
                up_read(&sinfo->groups_sem);
        }
        return sysfs_emit(buf, "none %u\n"
                               "small %u\n"
                               "medium %u\n"
                               "large %u\n",
                               none, small, medium, large);
}

#ifdef CONFIG_BTRFS_DEBUG
/*
 * Request chunk allocation with current chunk size.
 */
static ssize_t btrfs_force_chunk_alloc_store(struct kobject *kobj,
                                             struct kobj_attribute *a,
                                             const char *buf, size_t len)
{
        struct btrfs_space_info *space_info = to_space_info(kobj);
        struct btrfs_fs_info *fs_info = to_fs_info(get_btrfs_kobj(kobj));
        struct btrfs_trans_handle *trans;
        bool val;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (sb_rdonly(fs_info->sb))
                return -EROFS;

        ret = kstrtobool(buf, &val);
        if (ret)
                return ret;

        if (!val)
                return -EINVAL;

        /*
         * This is unsafe to be called from sysfs context and may cause
         * unexpected problems.
         */
        trans = btrfs_start_transaction(fs_info->tree_root, 0);
        if (IS_ERR(trans))
                return PTR_ERR(trans);
        ret = btrfs_force_chunk_alloc(trans, space_info->flags);
        btrfs_end_transaction(trans);

        if (ret == 1)
                return len;

        return -ENOSPC;
}
BTRFS_ATTR_W(space_info, force_chunk_alloc, btrfs_force_chunk_alloc_store);

#endif

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(bytes_zone_unusable);
SPACE_INFO_ATTR(disk_used);
SPACE_INFO_ATTR(disk_total);
SPACE_INFO_ATTR(reclaim_count);
SPACE_INFO_ATTR(reclaim_bytes);
SPACE_INFO_ATTR(reclaim_errors);
BTRFS_ATTR_RW(space_info, chunk_size, btrfs_chunk_size_show, btrfs_chunk_size_store);
BTRFS_ATTR(space_info, size_classes, btrfs_size_classes_show);

static ssize_t btrfs_sinfo_bg_reclaim_threshold_show(struct kobject *kobj,
                                                     struct kobj_attribute *a,
                                                     char *buf)
{
        struct btrfs_space_info *space_info = to_space_info(kobj);
        ssize_t ret;

        spin_lock(&space_info->lock);
        ret = sysfs_emit(buf, "%d\n", btrfs_calc_reclaim_threshold(space_info));
        spin_unlock(&space_info->lock);
        return ret;
}

static ssize_t btrfs_sinfo_bg_reclaim_threshold_store(struct kobject *kobj,
                                                      struct kobj_attribute *a,
                                                      const char *buf, size_t len)
{
        struct btrfs_space_info *space_info = to_space_info(kobj);
        int thresh;
        int ret;

        if (READ_ONCE(space_info->dynamic_reclaim))
                return -EINVAL;

        ret = kstrtoint(buf, 10, &thresh);
        if (ret)
                return ret;

        if (thresh < 0 || thresh > 100)
                return -EINVAL;

        WRITE_ONCE(space_info->bg_reclaim_threshold, thresh);

        return len;
}

BTRFS_ATTR_RW(space_info, bg_reclaim_threshold,
              btrfs_sinfo_bg_reclaim_threshold_show,
              btrfs_sinfo_bg_reclaim_threshold_store);

static ssize_t btrfs_sinfo_dynamic_reclaim_show(struct kobject *kobj,
                                                struct kobj_attribute *a,
                                                char *buf)
{
        struct btrfs_space_info *space_info = to_space_info(kobj);

        return sysfs_emit(buf, "%d\n", READ_ONCE(space_info->dynamic_reclaim));
}

static ssize_t btrfs_sinfo_dynamic_reclaim_store(struct kobject *kobj,
                                                 struct kobj_attribute *a,
                                                 const char *buf, size_t len)
{
        struct btrfs_space_info *space_info = to_space_info(kobj);
        int dynamic_reclaim;
        int ret;

        ret = kstrtoint(buf, 10, &dynamic_reclaim);
        if (ret)
                return ret;

        if (dynamic_reclaim < 0)
                return -EINVAL;

        WRITE_ONCE(space_info->dynamic_reclaim, dynamic_reclaim != 0);

        return len;
}

BTRFS_ATTR_RW(space_info, dynamic_reclaim,
              btrfs_sinfo_dynamic_reclaim_show,
              btrfs_sinfo_dynamic_reclaim_store);

static ssize_t btrfs_sinfo_periodic_reclaim_show(struct kobject *kobj,
                                                struct kobj_attribute *a,
                                                char *buf)
{
        struct btrfs_space_info *space_info = to_space_info(kobj);

        return sysfs_emit(buf, "%d\n", READ_ONCE(space_info->periodic_reclaim));
}

static ssize_t btrfs_sinfo_periodic_reclaim_store(struct kobject *kobj,
                                                 struct kobj_attribute *a,
                                                 const char *buf, size_t len)
{
        struct btrfs_space_info *space_info = to_space_info(kobj);
        int periodic_reclaim;
        int ret;

        ret = kstrtoint(buf, 10, &periodic_reclaim);
        if (ret)
                return ret;

        if (periodic_reclaim < 0)
                return -EINVAL;

        WRITE_ONCE(space_info->periodic_reclaim, periodic_reclaim != 0);

        return len;
}

BTRFS_ATTR_RW(space_info, periodic_reclaim,
              btrfs_sinfo_periodic_reclaim_show,
              btrfs_sinfo_periodic_reclaim_store);

/*
 * Allocation information about block group types.
 *
 * Path: /sys/fs/btrfs/<uuid>/allocation/<bg-type>/
 */
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, bytes_zone_unusable),
        BTRFS_ATTR_PTR(space_info, disk_used),
        BTRFS_ATTR_PTR(space_info, disk_total),
        BTRFS_ATTR_PTR(space_info, bg_reclaim_threshold),
        BTRFS_ATTR_PTR(space_info, dynamic_reclaim),
        BTRFS_ATTR_PTR(space_info, chunk_size),
        BTRFS_ATTR_PTR(space_info, size_classes),
        BTRFS_ATTR_PTR(space_info, reclaim_count),
        BTRFS_ATTR_PTR(space_info, reclaim_bytes),
        BTRFS_ATTR_PTR(space_info, reclaim_errors),
        BTRFS_ATTR_PTR(space_info, periodic_reclaim),
#ifdef CONFIG_BTRFS_DEBUG
        BTRFS_ATTR_PTR(space_info, force_chunk_alloc),
#endif
        NULL,
};
ATTRIBUTE_GROUPS(space_info);

static void space_info_release(struct kobject *kobj)
{
        struct btrfs_space_info *sinfo = to_space_info(kobj);
        kfree(sinfo);
}

static const struct kobj_type space_info_ktype = {
        .sysfs_ops = &kobj_sysfs_ops,
        .release = space_info_release,
        .default_groups = space_info_groups,
};

/*
 * Allocation information about block groups.
 *
 * Path: /sys/fs/btrfs/<uuid>/allocation/
 */
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 = sysfs_emit(buf, 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
         */
        set_bit(BTRFS_FS_NEED_TRANS_COMMIT, &fs_info->flags);
        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 sysfs_emit(buf, "%u\n", fs_info->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 sysfs_emit(buf, "%u\n", fs_info->sectorsize);
}

BTRFS_ATTR(, sectorsize, btrfs_sectorsize_show);

static ssize_t btrfs_commit_stats_show(struct kobject *kobj,
                                       struct kobj_attribute *a, char *buf)
{
        struct btrfs_fs_info *fs_info = to_fs_info(kobj);
        u64 now = ktime_get_ns();
        u64 start_time = fs_info->commit_stats.critical_section_start_time;
        u64 pending = 0;

        if (start_time)
                pending = now - start_time;

        return sysfs_emit(buf,
                "commits %llu\n"
                "cur_commit_ms %llu\n"
                "last_commit_ms %llu\n"
                "max_commit_ms %llu\n"
                "total_commit_ms %llu\n",
                fs_info->commit_stats.commit_count,
                div_u64(pending, NSEC_PER_MSEC),
                div_u64(fs_info->commit_stats.last_commit_dur, NSEC_PER_MSEC),
                div_u64(fs_info->commit_stats.max_commit_dur, NSEC_PER_MSEC),
                div_u64(fs_info->commit_stats.total_commit_dur, NSEC_PER_MSEC));
}

static ssize_t btrfs_commit_stats_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 val;
        int ret;

        if (!fs_info)
                return -EPERM;

        if (!capable(CAP_SYS_RESOURCE))
                return -EPERM;

        ret = kstrtoul(buf, 10, &val);
        if (ret)
                return ret;
        if (val)
                return -EINVAL;

        WRITE_ONCE(fs_info->commit_stats.max_commit_dur, 0);

        return len;
}
BTRFS_ATTR_RW(, commit_stats, btrfs_commit_stats_show, btrfs_commit_stats_store);

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 sysfs_emit(buf, "%u\n", fs_info->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 sysfs_emit(buf, "%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 ret;

        if (!fs_info)
                return -EPERM;

        if (!capable(CAP_SYS_RESOURCE))
                return -EPERM;

        ret = kstrtoul(buf, 10, &knob);
        if (ret)
                return ret;
        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 ssize_t btrfs_metadata_uuid_show(struct kobject *kobj,
                                struct kobj_attribute *a, char *buf)
{
        struct btrfs_fs_info *fs_info = to_fs_info(kobj);

        return sysfs_emit(buf, "%pU\n", fs_info->fs_devices->metadata_uuid);
}

BTRFS_ATTR(, metadata_uuid, btrfs_metadata_uuid_show);

static ssize_t btrfs_checksum_show(struct kobject *kobj,
                                   struct kobj_attribute *a, char *buf)
{
        struct btrfs_fs_info *fs_info = to_fs_info(kobj);
        u16 csum_type = btrfs_super_csum_type(fs_info->super_copy);
        const char *csum_name = btrfs_super_csum_name(csum_type);

        return sysfs_emit(buf, "%s (%s-lib)\n", csum_name, csum_name);
}

BTRFS_ATTR(, checksum, btrfs_checksum_show);

static ssize_t btrfs_exclusive_operation_show(struct kobject *kobj,
                struct kobj_attribute *a, char *buf)
{
        struct btrfs_fs_info *fs_info = to_fs_info(kobj);
        const char *str;

        switch (READ_ONCE(fs_info->exclusive_operation)) {
                case  BTRFS_EXCLOP_NONE:
                        str = "none\n";
                        break;
                case BTRFS_EXCLOP_BALANCE:
                        str = "balance\n";
                        break;
                case BTRFS_EXCLOP_BALANCE_PAUSED:
                        str = "balance paused\n";
                        break;
                case BTRFS_EXCLOP_DEV_ADD:
                        str = "device add\n";
                        break;
                case BTRFS_EXCLOP_DEV_REMOVE:
                        str = "device remove\n";
                        break;
                case BTRFS_EXCLOP_DEV_REPLACE:
                        str = "device replace\n";
                        break;
                case BTRFS_EXCLOP_RESIZE:
                        str = "resize\n";
                        break;
                case BTRFS_EXCLOP_SWAP_ACTIVATE:
                        str = "swap activate\n";
                        break;
                default:
                        str = "UNKNOWN\n";
                        break;
        }
        return sysfs_emit(buf, "%s", str);
}
BTRFS_ATTR(, exclusive_operation, btrfs_exclusive_operation_show);

static ssize_t btrfs_generation_show(struct kobject *kobj,
                                     struct kobj_attribute *a, char *buf)
{
        struct btrfs_fs_info *fs_info = to_fs_info(kobj);

        return sysfs_emit(buf, "%llu\n", btrfs_get_fs_generation(fs_info));
}
BTRFS_ATTR(, generation, btrfs_generation_show);

static ssize_t btrfs_temp_fsid_show(struct kobject *kobj,
                                    struct kobj_attribute *a, char *buf)
{
        struct btrfs_fs_info *fs_info = to_fs_info(kobj);

        return sysfs_emit(buf, "%d\n", fs_info->fs_devices->temp_fsid);
}
BTRFS_ATTR(, temp_fsid, btrfs_temp_fsid_show);

static const char *btrfs_read_policy_name[] = {
        "pid",
#ifdef CONFIG_BTRFS_EXPERIMENTAL
        "round-robin",
        "devid",
#endif
};

#ifdef CONFIG_BTRFS_EXPERIMENTAL

/* Global module configuration parameters. */
static char *read_policy;
char *btrfs_get_mod_read_policy(void)
{
        return read_policy;
}

/* Set perms to 0, disable /sys/module/btrfs/parameter/read_policy interface. */
module_param(read_policy, charp, 0);
MODULE_PARM_DESC(read_policy,
"Global read policy: pid (default), round-robin[:<min_contig_read>], devid[:<devid>]");
#endif

int btrfs_read_policy_to_enum(const char *str, s64 *value_ret)
{
        char param[32];
        char __maybe_unused *value_str;

        if (!str || strlen(str) == 0)
                return 0;

        strscpy(param, str);

#ifdef CONFIG_BTRFS_EXPERIMENTAL
        /* Separate value from input in policy:value format. */
        value_str = strchr(param, ':');
        if (value_str) {
                char *retptr;

                *value_str = 0;
                value_str++;
                if (!value_ret)
                        return -EINVAL;

                *value_ret = memparse(value_str, &retptr);
                /* There could be any trailing typos after the value. */
                retptr = skip_spaces(retptr);
                if (*retptr != 0 || *value_ret <= 0)
                        return -EINVAL;
        }
#endif

        return sysfs_match_string(btrfs_read_policy_name, param);
}

#ifdef CONFIG_BTRFS_EXPERIMENTAL
int __init btrfs_read_policy_init(void)
{
        s64 value;

        if (btrfs_read_policy_to_enum(read_policy, &value) == -EINVAL) {
                btrfs_err(NULL, "invalid read policy or value %s", read_policy);
                return -EINVAL;
        }

        return 0;
}
#endif

static ssize_t btrfs_read_policy_show(struct kobject *kobj,
                                      struct kobj_attribute *a, char *buf)
{
        struct btrfs_fs_devices *fs_devices = to_fs_devs(kobj);
        const enum btrfs_read_policy policy = READ_ONCE(fs_devices->read_policy);
        ssize_t ret = 0;
        int i;

        for (i = 0; i < BTRFS_NR_READ_POLICY; i++) {
                if (ret != 0)
                        ret += sysfs_emit_at(buf, ret, " ");

                if (i == policy)
                        ret += sysfs_emit_at(buf, ret, "[");

                ret += sysfs_emit_at(buf, ret, "%s", btrfs_read_policy_name[i]);

#ifdef CONFIG_BTRFS_EXPERIMENTAL
                if (i == BTRFS_READ_POLICY_RR)
                        ret += sysfs_emit_at(buf, ret, ":%u",
                                             READ_ONCE(fs_devices->rr_min_contig_read));

                if (i == BTRFS_READ_POLICY_DEVID)
                        ret += sysfs_emit_at(buf, ret, ":%llu",
                                             READ_ONCE(fs_devices->read_devid));
#endif
                if (i == policy)
                        ret += sysfs_emit_at(buf, ret, "]");
        }

        ret += sysfs_emit_at(buf, ret, "\n");

        return ret;
}

static ssize_t btrfs_read_policy_store(struct kobject *kobj,
                                       struct kobj_attribute *a,
                                       const char *buf, size_t len)
{
        struct btrfs_fs_devices *fs_devices = to_fs_devs(kobj);
        int index;
        s64 value = -1;

        index = btrfs_read_policy_to_enum(buf, &value);
        if (index < 0)
                return -EINVAL;

#ifdef CONFIG_BTRFS_EXPERIMENTAL
        /* If moving from RR then disable collecting fs stats. */
        if (fs_devices->read_policy == BTRFS_READ_POLICY_RR && index != BTRFS_READ_POLICY_RR)
                fs_devices->collect_fs_stats = false;

        if (index == BTRFS_READ_POLICY_RR) {
                if (value != -1) {
                        const u32 sectorsize = fs_devices->fs_info->sectorsize;

                        if (!IS_ALIGNED(value, sectorsize)) {
                                u64 temp_value = round_up(value, sectorsize);

                                btrfs_debug(fs_devices->fs_info,
"read_policy: min contig read %lld should be multiple of sectorsize %u, rounded to %llu",
                                          value, sectorsize, temp_value);
                                value = temp_value;
                        }
                } else {
                        value = BTRFS_DEFAULT_RR_MIN_CONTIG_READ;
                }

                if (index != READ_ONCE(fs_devices->read_policy) ||
                    value != READ_ONCE(fs_devices->rr_min_contig_read)) {
                        WRITE_ONCE(fs_devices->read_policy, index);
                        WRITE_ONCE(fs_devices->rr_min_contig_read, value);

                        btrfs_info(fs_devices->fs_info, "read policy set to '%s:%lld'",
                                   btrfs_read_policy_name[index], value);
                }

                fs_devices->collect_fs_stats = true;

                return len;
        }

        if (index == BTRFS_READ_POLICY_DEVID) {
                if (value != -1) {
                        BTRFS_DEV_LOOKUP_ARGS(args);

                        /* Validate input devid. */
                        args.devid = value;
                        if (btrfs_find_device(fs_devices, &args) == NULL)
                                return -EINVAL;
                } else {
                        /* Set default devid to the devid of the latest device. */
                        value = fs_devices->latest_dev->devid;
                }

                if (index != READ_ONCE(fs_devices->read_policy) ||
                    value != READ_ONCE(fs_devices->read_devid)) {
                        WRITE_ONCE(fs_devices->read_policy, index);
                        WRITE_ONCE(fs_devices->read_devid, value);

                        btrfs_info(fs_devices->fs_info, "read policy set to '%s:%llu'",
                                   btrfs_read_policy_name[index], value);
                }

                return len;
        }
#endif
        if (index != READ_ONCE(fs_devices->read_policy)) {
                WRITE_ONCE(fs_devices->read_policy, index);
                btrfs_info(fs_devices->fs_info, "read policy set to '%s'",
                           btrfs_read_policy_name[index]);
        }

        return len;
}
BTRFS_ATTR_RW(, read_policy, btrfs_read_policy_show, btrfs_read_policy_store);

static ssize_t btrfs_bg_reclaim_threshold_show(struct kobject *kobj,
                                               struct kobj_attribute *a,
                                               char *buf)
{
        struct btrfs_fs_info *fs_info = to_fs_info(kobj);

        return sysfs_emit(buf, "%d\n", READ_ONCE(fs_info->bg_reclaim_threshold));
}

static ssize_t btrfs_bg_reclaim_threshold_store(struct kobject *kobj,
                                                struct kobj_attribute *a,
                                                const char *buf, size_t len)
{
        struct btrfs_fs_info *fs_info = to_fs_info(kobj);
        int thresh;
        int ret;

        ret = kstrtoint(buf, 10, &thresh);
        if (ret)
                return ret;

#ifdef CONFIG_BTRFS_DEBUG
        if (thresh != 0 && (thresh > 100))
                return -EINVAL;
#else
        if (thresh != 0 && (thresh <= 50 || thresh > 100))
                return -EINVAL;
#endif

        WRITE_ONCE(fs_info->bg_reclaim_threshold, thresh);

        return len;
}
BTRFS_ATTR_RW(, bg_reclaim_threshold, btrfs_bg_reclaim_threshold_show,
              btrfs_bg_reclaim_threshold_store);

/*
 * Per-filesystem information and stats.
 *
 * Path: /sys/fs/btrfs/<uuid>/
 */
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),
        BTRFS_ATTR_PTR(, metadata_uuid),
        BTRFS_ATTR_PTR(, checksum),
        BTRFS_ATTR_PTR(, exclusive_operation),
        BTRFS_ATTR_PTR(, generation),
        BTRFS_ATTR_PTR(, read_policy),
        BTRFS_ATTR_PTR(, bg_reclaim_threshold),
        BTRFS_ATTR_PTR(, commit_stats),
        BTRFS_ATTR_PTR(, temp_fsid),
        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 const 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;
}

static struct kobject *get_btrfs_kobj(struct kobject *kobj)
{
        while (kobj) {
                if (kobj->ktype == &btrfs_ktype)
                        return kobj;
                kobj = kobj->parent;
        }
        return NULL;
}

#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_assert(ARRAY_SIZE(btrfs_unknown_feature_names) ==
              ARRAY_SIZE(btrfs_feature_attrs));
static_assert(ARRAY_SIZE(btrfs_unknown_feature_names[0]) ==
              ARRAY_SIZE(btrfs_feature_attrs[0]));

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->devinfo_kobj) {
                kobject_del(fs_devs->devinfo_kobj);
                kobject_put(fs_devs->devinfo_kobj);
                fs_devs->devinfo_kobj = NULL;
        }

        if (fs_devs->devices_kobj) {
                kobject_del(fs_devs->devices_kobj);
                kobject_put(fs_devs->devices_kobj);
                fs_devs->devices_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);
        }
}

static void btrfs_sysfs_remove_fs_devices(struct btrfs_fs_devices *fs_devices)
{
        struct btrfs_device *device;
        struct btrfs_fs_devices *seed;

        list_for_each_entry(device, &fs_devices->devices, dev_list)
                btrfs_sysfs_remove_device(device);

        list_for_each_entry(seed, &fs_devices->seed_list, seed_list) {
                list_for_each_entry(device, &seed->devices, dev_list)
                        btrfs_sysfs_remove_device(device);
        }
}

void btrfs_sysfs_remove_mounted(struct btrfs_fs_info *fs_info)
{
        struct kobject *fsid_kobj = &fs_info->fs_devices->fsid_kobj;

        sysfs_remove_link(fsid_kobj, "bdi");

        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);
        }
        if (fs_info->discard_kobj) {
                sysfs_remove_files(fs_info->discard_kobj, discard_attrs);
                kobject_del(fs_info->discard_kobj);
                kobject_put(fs_info->discard_kobj);
        }
#ifdef CONFIG_BTRFS_DEBUG
        if (fs_info->debug_kobj) {
                sysfs_remove_files(fs_info->debug_kobj, btrfs_debug_mount_attrs);
                kobject_del(fs_info->debug_kobj);
                kobject_put(fs_info->debug_kobj);
        }
#endif
        addrm_unknown_feature_attrs(fs_info, false);
        sysfs_remove_group(fsid_kobj, &btrfs_feature_attr_group);
        sysfs_remove_files(fsid_kobj, btrfs_attrs);
        btrfs_sysfs_remove_fs_devices(fs_info->fs_devices);
}

static const char * const btrfs_feature_set_names[FEAT_MAX] = {
        [FEAT_COMPAT]    = "compat",
        [FEAT_COMPAT_RO] = "compat_ro",
        [FEAT_INCOMPAT]  = "incompat",
};

const char *btrfs_feature_set_name(enum btrfs_feature_set set)
{
        return btrfs_feature_set_names[set];
}

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 += scnprintf(str + len, bufsize - len, "%s%s",
                                len ? "," : "", name);
        }

        return str;
}

static void init_feature_attrs(void)
{
        struct btrfs_feature_attr *fa;
        int set, i;

        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;
                }
        }
}

/*
 * Create a sysfs entry for a given block group type at path
 * /sys/fs/btrfs/UUID/allocation/data/TYPE
 */
void btrfs_sysfs_add_block_group_type(struct btrfs_block_group *cache)
{
        struct btrfs_fs_info *fs_info = cache->fs_info;
        struct btrfs_space_info *space_info = cache->space_info;
        struct raid_kobject *rkobj;
        const int index = btrfs_bg_flags_to_raid_index(cache->flags);
        unsigned int nofs_flag;
        int ret;

        /*
         * Setup a NOFS context because kobject_add(), deep in its call chain,
         * does GFP_KERNEL allocations, and we are often called in a context
         * where if reclaim is triggered we can deadlock (we are either holding
         * a transaction handle or some lock required for a transaction
         * commit).
         */
        nofs_flag = memalloc_nofs_save();

        rkobj = kzalloc_obj(*rkobj, GFP_NOFS);
        if (!rkobj) {
                memalloc_nofs_restore(nofs_flag);
                btrfs_warn(cache->fs_info,
                                "couldn't alloc memory for raid level kobject");
                return;
        }

        rkobj->flags = cache->flags;
        kobject_init(&rkobj->kobj, &btrfs_raid_ktype);

        /*
         * We call this either on mount, or if we've created a block group for a
         * new index type while running (i.e. when restriping).  The running
         * case is tricky because we could race with other threads, so we need
         * to have this check to make sure we didn't already init the kobject.
         *
         * We don't have to protect on the free side because it only happens on
         * unmount.
         */
        spin_lock(&space_info->lock);
        if (space_info->block_group_kobjs[index]) {
                spin_unlock(&space_info->lock);
                kobject_put(&rkobj->kobj);
                return;
        } else {
                space_info->block_group_kobjs[index] = &rkobj->kobj;
        }
        spin_unlock(&space_info->lock);

        ret = kobject_add(&rkobj->kobj, &space_info->kobj, "%s",
                          btrfs_bg_type_to_raid_name(rkobj->flags));
        memalloc_nofs_restore(nofs_flag);
        if (ret) {
                spin_lock(&space_info->lock);
                space_info->block_group_kobjs[index] = NULL;
                spin_unlock(&space_info->lock);
                kobject_put(&rkobj->kobj);
                btrfs_warn(fs_info,
                        "failed to add kobject for block cache, ignoring");
                return;
        }
}

/*
 * Remove sysfs directories for all block group types of a given space info and
 * the space info as well
 */
void btrfs_sysfs_remove_space_info(struct btrfs_space_info *space_info)
{
        int i;

        for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
                struct kobject *kobj;

                kobj = space_info->block_group_kobjs[i];
                space_info->block_group_kobjs[i] = NULL;
                if (kobj) {
                        kobject_del(kobj);
                        kobject_put(kobj);
                }
        }
        kobject_del(&space_info->kobj);
        kobject_put(&space_info->kobj);
}

static const char *alloc_name(struct btrfs_space_info *space_info)
{
        u64 flags = space_info->flags;

        switch (flags) {
        case BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA:
                return "mixed";
        case BTRFS_BLOCK_GROUP_METADATA:
                switch (space_info->subgroup_id) {
                case BTRFS_SUB_GROUP_PRIMARY:
                        return "metadata";
                case BTRFS_SUB_GROUP_TREELOG:
                        return "metadata-treelog";
                default:
                        WARN_ON_ONCE(1);
                        return "metadata (unknown sub-group)";
                }
        case BTRFS_BLOCK_GROUP_DATA:
                switch (space_info->subgroup_id) {
                case BTRFS_SUB_GROUP_PRIMARY:
                        return "data";
                case BTRFS_SUB_GROUP_DATA_RELOC:
                        return "data-reloc";
                default:
                        WARN_ON_ONCE(1);
                        return "data (unknown sub-group)";
                }
        case BTRFS_BLOCK_GROUP_SYSTEM:
                ASSERT(space_info->subgroup_id == BTRFS_SUB_GROUP_PRIMARY);
                return "system";
        case BTRFS_BLOCK_GROUP_METADATA_REMAP:
                return "metadata-remap";
        default:
                WARN_ON(1);
                return "invalid-combination";
        }
}

/*
 * Create a sysfs entry for a space info type at path
 * /sys/fs/btrfs/UUID/allocation/TYPE
 */
int btrfs_sysfs_add_space_info_type(struct btrfs_space_info *space_info)
{
        int ret;

        ret = kobject_init_and_add(&space_info->kobj, &space_info_ktype,
                                   space_info->fs_info->space_info_kobj, "%s",
                                   alloc_name(space_info));
        if (ret) {
                kobject_put(&space_info->kobj);
                return ret;
        }

        return 0;
}

void btrfs_sysfs_remove_device(struct btrfs_device *device)
{
        struct kobject *devices_kobj;

        /*
         * Seed fs_devices devices_kobj aren't used, fetch kobject from the
         * fs_info::fs_devices.
         */
        devices_kobj = device->fs_info->fs_devices->devices_kobj;
        ASSERT(devices_kobj);

        if (device->bdev)
                sysfs_remove_link(devices_kobj, bdev_kobj(device->bdev)->name);

        if (device->devid_kobj.state_initialized) {
                kobject_del(&device->devid_kobj);
                kobject_put(&device->devid_kobj);
                wait_for_completion(&device->kobj_unregister);
        }
}

static ssize_t btrfs_devinfo_in_fs_metadata_show(struct kobject *kobj,
                                                 struct kobj_attribute *a,
                                                 char *buf)
{
        int val;
        struct btrfs_device *device = container_of(kobj, struct btrfs_device,
                                                   devid_kobj);

        val = !!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);

        return sysfs_emit(buf, "%d\n", val);
}
BTRFS_ATTR(devid, in_fs_metadata, btrfs_devinfo_in_fs_metadata_show);

static ssize_t btrfs_devinfo_missing_show(struct kobject *kobj,
                                        struct kobj_attribute *a, char *buf)
{
        int val;
        struct btrfs_device *device = container_of(kobj, struct btrfs_device,
                                                   devid_kobj);

        val = !!test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state);

        return sysfs_emit(buf, "%d\n", val);
}
BTRFS_ATTR(devid, missing, btrfs_devinfo_missing_show);

static ssize_t btrfs_devinfo_replace_target_show(struct kobject *kobj,
                                                 struct kobj_attribute *a,
                                                 char *buf)
{
        int val;
        struct btrfs_device *device = container_of(kobj, struct btrfs_device,
                                                   devid_kobj);

        val = !!test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);

        return sysfs_emit(buf, "%d\n", val);
}
BTRFS_ATTR(devid, replace_target, btrfs_devinfo_replace_target_show);

static ssize_t btrfs_devinfo_scrub_speed_max_show(struct kobject *kobj,
                                             struct kobj_attribute *a,
                                             char *buf)
{
        struct btrfs_device *device = container_of(kobj, struct btrfs_device,
                                                   devid_kobj);

        return sysfs_emit(buf, "%llu\n", READ_ONCE(device->scrub_speed_max));
}

static ssize_t btrfs_devinfo_scrub_speed_max_store(struct kobject *kobj,
                                              struct kobj_attribute *a,
                                              const char *buf, size_t len)
{
        struct btrfs_device *device = container_of(kobj, struct btrfs_device,
                                                   devid_kobj);
        char *endptr;
        unsigned long long limit;

        limit = memparse(buf, &endptr);
        /* There could be trailing '\n', also catch any typos after the value. */
        endptr = skip_spaces(endptr);
        if (*endptr != 0)
                return -EINVAL;
        WRITE_ONCE(device->scrub_speed_max, limit);
        return len;
}
BTRFS_ATTR_RW(devid, scrub_speed_max, btrfs_devinfo_scrub_speed_max_show,
              btrfs_devinfo_scrub_speed_max_store);

static ssize_t btrfs_devinfo_writeable_show(struct kobject *kobj,
                                            struct kobj_attribute *a, char *buf)
{
        int val;
        struct btrfs_device *device = container_of(kobj, struct btrfs_device,
                                                   devid_kobj);

        val = !!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);

        return sysfs_emit(buf, "%d\n", val);
}
BTRFS_ATTR(devid, writeable, btrfs_devinfo_writeable_show);

static ssize_t btrfs_devinfo_fsid_show(struct kobject *kobj,
                                       struct kobj_attribute *a, char *buf)
{
        struct btrfs_device *device = container_of(kobj, struct btrfs_device,
                                                   devid_kobj);

        return sysfs_emit(buf, "%pU\n", device->fs_devices->fsid);
}
BTRFS_ATTR(devid, fsid, btrfs_devinfo_fsid_show);

static ssize_t btrfs_devinfo_error_stats_show(struct kobject *kobj,
                struct kobj_attribute *a, char *buf)
{
        struct btrfs_device *device = container_of(kobj, struct btrfs_device,
                                                   devid_kobj);

        if (!device->dev_stats_valid)
                return sysfs_emit(buf, "invalid\n");

        /*
         * Print all at once so we get a snapshot of all values from the same
         * time. Keep them in sync and in order of definition of
         * btrfs_dev_stat_values.
         */
        return sysfs_emit(buf,
                "write_errs %d\n"
                "read_errs %d\n"
                "flush_errs %d\n"
                "corruption_errs %d\n"
                "generation_errs %d\n",
                btrfs_dev_stat_read(device, BTRFS_DEV_STAT_WRITE_ERRS),
                btrfs_dev_stat_read(device, BTRFS_DEV_STAT_READ_ERRS),
                btrfs_dev_stat_read(device, BTRFS_DEV_STAT_FLUSH_ERRS),
                btrfs_dev_stat_read(device, BTRFS_DEV_STAT_CORRUPTION_ERRS),
                btrfs_dev_stat_read(device, BTRFS_DEV_STAT_GENERATION_ERRS));
}
BTRFS_ATTR(devid, error_stats, btrfs_devinfo_error_stats_show);

/*
 * Information about one device.
 *
 * Path: /sys/fs/btrfs/<uuid>/devinfo/<devid>/
 */
static struct attribute *devid_attrs[] = {
        BTRFS_ATTR_PTR(devid, error_stats),
        BTRFS_ATTR_PTR(devid, fsid),
        BTRFS_ATTR_PTR(devid, in_fs_metadata),
        BTRFS_ATTR_PTR(devid, missing),
        BTRFS_ATTR_PTR(devid, replace_target),
        BTRFS_ATTR_PTR(devid, scrub_speed_max),
        BTRFS_ATTR_PTR(devid, writeable),
        NULL
};
ATTRIBUTE_GROUPS(devid);

static void btrfs_release_devid_kobj(struct kobject *kobj)
{
        struct btrfs_device *device = container_of(kobj, struct btrfs_device,
                                                   devid_kobj);

        memset(&device->devid_kobj, 0, sizeof(struct kobject));
        complete(&device->kobj_unregister);
}

static const struct kobj_type devid_ktype = {
        .sysfs_ops      = &kobj_sysfs_ops,
        .default_groups = devid_groups,
        .release        = btrfs_release_devid_kobj,
};

int btrfs_sysfs_add_device(struct btrfs_device *device)
{
        int ret;
        unsigned int nofs_flag;
        struct kobject *devices_kobj;
        struct kobject *devinfo_kobj;

        /*
         * Make sure we use the fs_info::fs_devices to fetch the kobjects even
         * for the seed fs_devices
         */
        devices_kobj = device->fs_info->fs_devices->devices_kobj;
        devinfo_kobj = device->fs_info->fs_devices->devinfo_kobj;
        ASSERT(devices_kobj);
        ASSERT(devinfo_kobj);

        nofs_flag = memalloc_nofs_save();

        if (device->bdev) {
                struct kobject *disk_kobj = bdev_kobj(device->bdev);

                ret = sysfs_create_link(devices_kobj, disk_kobj, disk_kobj->name);
                if (ret) {
                        btrfs_warn(device->fs_info,
                                "creating sysfs device link for devid %llu failed: %d",
                                device->devid, ret);
                        goto out;
                }
        }

        init_completion(&device->kobj_unregister);
        ret = kobject_init_and_add(&device->devid_kobj, &devid_ktype,
                                   devinfo_kobj, "%llu", device->devid);
        if (ret) {
                kobject_put(&device->devid_kobj);
                btrfs_warn(device->fs_info,
                           "devinfo init for devid %llu failed: %d",
                           device->devid, ret);
        }

out:
        memalloc_nofs_restore(nofs_flag);
        return ret;
}

static int btrfs_sysfs_add_fs_devices(struct btrfs_fs_devices *fs_devices)
{
        int ret;
        struct btrfs_device *device;
        struct btrfs_fs_devices *seed;

        list_for_each_entry(device, &fs_devices->devices, dev_list) {
                ret = btrfs_sysfs_add_device(device);
                if (ret)
                        goto fail;
        }

        list_for_each_entry(seed, &fs_devices->seed_list, seed_list) {
                list_for_each_entry(device, &seed->devices, dev_list) {
                        ret = btrfs_sysfs_add_device(device);
                        if (ret)
                                goto fail;
                }
        }

        return 0;

fail:
        btrfs_sysfs_remove_fs_devices(fs_devices);
        return ret;
}

void btrfs_kobject_uevent(struct block_device *bdev, enum kobject_action action)
{
        int ret;

        ret = kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, action);
        if (ret)
                btrfs_warn(NULL, "sending event %d to kobject: '%s' (%p): failed",
                        action, kobject_name(&disk_to_dev(bdev->bd_disk)->kobj),
                        &disk_to_dev(bdev->bd_disk)->kobj);
}

void btrfs_sysfs_update_sprout_fsid(struct btrfs_fs_devices *fs_devices)

{
        char fsid_buf[BTRFS_UUID_UNPARSED_SIZE];

        /*
         * Sprouting changes fsid of the mounted filesystem, rename the fsid
         * directory
         */
        snprintf(fsid_buf, BTRFS_UUID_UNPARSED_SIZE, "%pU", fs_devices->fsid);
        if (kobject_rename(&fs_devices->fsid_kobj, fsid_buf))
                btrfs_warn(fs_devices->fs_info,
                                "sysfs: failed to create fsid for sprout");
}

void btrfs_sysfs_update_devid(struct btrfs_device *device)
{
        char tmp[24];

        snprintf(tmp, sizeof(tmp), "%llu", device->devid);

        if (kobject_rename(&device->devid_kobj, tmp))
                btrfs_warn(device->fs_devices->fs_info,
                           "sysfs: failed to update devid for %llu",
                           device->devid);
}

/* /sys/fs/btrfs/ entry */
static struct kset *btrfs_kset;

/*
 * Creates:
 *              /sys/fs/btrfs/UUID
 *
 * Can be called by the device discovery thread.
 */
int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs)
{
        int ret;

        init_completion(&fs_devs->kobj_unregister);
        fs_devs->fsid_kobj.kset = btrfs_kset;
        ret = kobject_init_and_add(&fs_devs->fsid_kobj, &btrfs_ktype, NULL,
                                   "%pU", fs_devs->fsid);
        if (ret) {
                kobject_put(&fs_devs->fsid_kobj);
                return ret;
        }

        fs_devs->devices_kobj = kobject_create_and_add("devices",
                                                       &fs_devs->fsid_kobj);
        if (!fs_devs->devices_kobj) {
                btrfs_err(fs_devs->fs_info,
                          "failed to init sysfs device interface");
                btrfs_sysfs_remove_fsid(fs_devs);
                return -ENOMEM;
        }

        fs_devs->devinfo_kobj = kobject_create_and_add("devinfo",
                                                       &fs_devs->fsid_kobj);
        if (!fs_devs->devinfo_kobj) {
                btrfs_err(fs_devs->fs_info,
                          "failed to init sysfs devinfo kobject");
                btrfs_sysfs_remove_fsid(fs_devs);
                return -ENOMEM;
        }

        return 0;
}

int btrfs_sysfs_add_mounted(struct btrfs_fs_info *fs_info)
{
        int ret;
        struct btrfs_fs_devices *fs_devs = fs_info->fs_devices;
        struct kobject *fsid_kobj = &fs_devs->fsid_kobj;

        ret = btrfs_sysfs_add_fs_devices(fs_devs);
        if (ret)
                return ret;

        ret = sysfs_create_files(fsid_kobj, btrfs_attrs);
        if (ret) {
                btrfs_sysfs_remove_fs_devices(fs_devs);
                return ret;
        }

        ret = sysfs_create_group(fsid_kobj, &btrfs_feature_attr_group);
        if (ret)
                goto failure;

#ifdef CONFIG_BTRFS_DEBUG
        fs_info->debug_kobj = kobject_create_and_add("debug", fsid_kobj);
        if (!fs_info->debug_kobj) {
                ret = -ENOMEM;
                goto failure;
        }

        ret = sysfs_create_files(fs_info->debug_kobj, btrfs_debug_mount_attrs);
        if (ret)
                goto failure;
#endif

        /* Discard directory */
        fs_info->discard_kobj = kobject_create_and_add("discard", fsid_kobj);
        if (!fs_info->discard_kobj) {
                ret = -ENOMEM;
                goto failure;
        }

        ret = sysfs_create_files(fs_info->discard_kobj, discard_attrs);
        if (ret)
                goto failure;

        ret = addrm_unknown_feature_attrs(fs_info, true);
        if (ret)
                goto failure;

        ret = sysfs_create_link(fsid_kobj, &fs_info->sb->s_bdi->dev->kobj, "bdi");
        if (ret)
                goto failure;

        fs_info->space_info_kobj = kobject_create_and_add("allocation",
                                                  fsid_kobj);
        if (!fs_info->space_info_kobj) {
                ret = -ENOMEM;
                goto failure;
        }

        ret = sysfs_create_files(fs_info->space_info_kobj, allocation_attrs);
        if (ret)
                goto failure;

        return 0;
failure:
        btrfs_sysfs_remove_mounted(fs_info);
        return ret;
}

static ssize_t qgroup_enabled_show(struct kobject *qgroups_kobj,
                                   struct kobj_attribute *a,
                                   char *buf)
{
        struct btrfs_fs_info *fs_info = to_fs_info(qgroups_kobj->parent);
        bool enabled;

        spin_lock(&fs_info->qgroup_lock);
        enabled = fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON;
        spin_unlock(&fs_info->qgroup_lock);

        return sysfs_emit(buf, "%d\n", enabled);
}
BTRFS_ATTR(qgroups, enabled, qgroup_enabled_show);

static ssize_t qgroup_mode_show(struct kobject *qgroups_kobj,
                                struct kobj_attribute *a,
                                char *buf)
{
        struct btrfs_fs_info *fs_info = to_fs_info(qgroups_kobj->parent);
        ssize_t ret = 0;

        spin_lock(&fs_info->qgroup_lock);
        ASSERT(btrfs_qgroup_enabled(fs_info));
        switch (btrfs_qgroup_mode(fs_info)) {
        case BTRFS_QGROUP_MODE_FULL:
                ret = sysfs_emit(buf, "qgroup\n");
                break;
        case BTRFS_QGROUP_MODE_SIMPLE:
                ret = sysfs_emit(buf, "squota\n");
                break;
        default:
                btrfs_warn(fs_info, "unexpected qgroup mode %d\n",
                           btrfs_qgroup_mode(fs_info));
                break;
        }
        spin_unlock(&fs_info->qgroup_lock);

        return ret;
}
BTRFS_ATTR(qgroups, mode, qgroup_mode_show);

static ssize_t qgroup_inconsistent_show(struct kobject *qgroups_kobj,
                                        struct kobj_attribute *a,
                                        char *buf)
{
        struct btrfs_fs_info *fs_info = to_fs_info(qgroups_kobj->parent);
        bool inconsistent;

        spin_lock(&fs_info->qgroup_lock);
        inconsistent = (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT);
        spin_unlock(&fs_info->qgroup_lock);

        return sysfs_emit(buf, "%d\n", inconsistent);
}
BTRFS_ATTR(qgroups, inconsistent, qgroup_inconsistent_show);

static ssize_t qgroup_drop_subtree_thres_show(struct kobject *qgroups_kobj,
                                              struct kobj_attribute *a,
                                              char *buf)
{
        struct btrfs_fs_info *fs_info = to_fs_info(qgroups_kobj->parent);
        u8 result;

        spin_lock(&fs_info->qgroup_lock);
        result = fs_info->qgroup_drop_subtree_thres;
        spin_unlock(&fs_info->qgroup_lock);

        return sysfs_emit(buf, "%d\n", result);
}

static ssize_t qgroup_drop_subtree_thres_store(struct kobject *qgroups_kobj,
                                               struct kobj_attribute *a,
                                               const char *buf, size_t len)
{
        struct btrfs_fs_info *fs_info = to_fs_info(qgroups_kobj->parent);
        u8 new_thres;
        int ret;

        ret = kstrtou8(buf, 10, &new_thres);
        if (ret)
                return -EINVAL;

        if (new_thres > BTRFS_MAX_LEVEL)
                return -EINVAL;

        spin_lock(&fs_info->qgroup_lock);
        fs_info->qgroup_drop_subtree_thres = new_thres;
        spin_unlock(&fs_info->qgroup_lock);

        return len;
}
BTRFS_ATTR_RW(qgroups, drop_subtree_threshold, qgroup_drop_subtree_thres_show,
              qgroup_drop_subtree_thres_store);

/*
 * Qgroups global info
 *
 * Path: /sys/fs/btrfs/<uuid>/qgroups/
 */
static struct attribute *qgroups_attrs[] = {
        BTRFS_ATTR_PTR(qgroups, enabled),
        BTRFS_ATTR_PTR(qgroups, inconsistent),
        BTRFS_ATTR_PTR(qgroups, drop_subtree_threshold),
        BTRFS_ATTR_PTR(qgroups, mode),
        NULL
};
ATTRIBUTE_GROUPS(qgroups);

static void qgroups_release(struct kobject *kobj)
{
        kfree(kobj);
}

static const struct kobj_type qgroups_ktype = {
        .sysfs_ops = &kobj_sysfs_ops,
        .default_groups = qgroups_groups,
        .release = qgroups_release,
};

static inline struct btrfs_fs_info *qgroup_kobj_to_fs_info(struct kobject *kobj)
{
        return to_fs_info(kobj->parent->parent);
}

#define QGROUP_ATTR(_member, _show_name)                                        \
static ssize_t btrfs_qgroup_show_##_member(struct kobject *qgroup_kobj,         \
                                           struct kobj_attribute *a,            \
                                           char *buf)                           \
{                                                                               \
        struct btrfs_fs_info *fs_info = qgroup_kobj_to_fs_info(qgroup_kobj);    \
        struct btrfs_qgroup *qgroup = container_of(qgroup_kobj,                 \
                        struct btrfs_qgroup, kobj);                             \
        return btrfs_show_u64(&qgroup->_member, &fs_info->qgroup_lock, buf);    \
}                                                                               \
BTRFS_ATTR(qgroup, _show_name, btrfs_qgroup_show_##_member)

#define QGROUP_RSV_ATTR(_name, _type)                                           \
static ssize_t btrfs_qgroup_rsv_show_##_name(struct kobject *qgroup_kobj,       \
                                             struct kobj_attribute *a,          \
                                             char *buf)                         \
{                                                                               \
        struct btrfs_fs_info *fs_info = qgroup_kobj_to_fs_info(qgroup_kobj);    \
        struct btrfs_qgroup *qgroup = container_of(qgroup_kobj,                 \
                        struct btrfs_qgroup, kobj);                             \
        return btrfs_show_u64(&qgroup->rsv.values[_type],                       \
                        &fs_info->qgroup_lock, buf);                            \
}                                                                               \
BTRFS_ATTR(qgroup, rsv_##_name, btrfs_qgroup_rsv_show_##_name)

QGROUP_ATTR(rfer, referenced);
QGROUP_ATTR(excl, exclusive);
QGROUP_ATTR(max_rfer, max_referenced);
QGROUP_ATTR(max_excl, max_exclusive);
QGROUP_ATTR(lim_flags, limit_flags);
QGROUP_RSV_ATTR(data, BTRFS_QGROUP_RSV_DATA);
QGROUP_RSV_ATTR(meta_pertrans, BTRFS_QGROUP_RSV_META_PERTRANS);
QGROUP_RSV_ATTR(meta_prealloc, BTRFS_QGROUP_RSV_META_PREALLOC);

/*
 * Qgroup information.
 *
 * Path: /sys/fs/btrfs/<uuid>/qgroups/<level>_<qgroupid>/
 */
static struct attribute *qgroup_attrs[] = {
        BTRFS_ATTR_PTR(qgroup, referenced),
        BTRFS_ATTR_PTR(qgroup, exclusive),
        BTRFS_ATTR_PTR(qgroup, max_referenced),
        BTRFS_ATTR_PTR(qgroup, max_exclusive),
        BTRFS_ATTR_PTR(qgroup, limit_flags),
        BTRFS_ATTR_PTR(qgroup, rsv_data),
        BTRFS_ATTR_PTR(qgroup, rsv_meta_pertrans),
        BTRFS_ATTR_PTR(qgroup, rsv_meta_prealloc),
        NULL
};
ATTRIBUTE_GROUPS(qgroup);

static void qgroup_release(struct kobject *kobj)
{
        struct btrfs_qgroup *qgroup = container_of(kobj, struct btrfs_qgroup, kobj);

        memset(&qgroup->kobj, 0, sizeof(*kobj));
}

static const struct kobj_type qgroup_ktype = {
        .sysfs_ops = &kobj_sysfs_ops,
        .release = qgroup_release,
        .default_groups = qgroup_groups,
};

int btrfs_sysfs_add_one_qgroup(struct btrfs_fs_info *fs_info,
                                struct btrfs_qgroup *qgroup)
{
        struct kobject *qgroups_kobj = fs_info->qgroups_kobj;
        int ret;

        if (btrfs_is_testing(fs_info))
                return 0;
        if (qgroup->kobj.state_initialized)
                return 0;
        if (!qgroups_kobj)
                return -EINVAL;

        ret = kobject_init_and_add(&qgroup->kobj, &qgroup_ktype, qgroups_kobj,
                        "%hu_%llu", btrfs_qgroup_level(qgroup->qgroupid),
                        btrfs_qgroup_subvolid(qgroup->qgroupid));
        if (ret < 0)
                kobject_put(&qgroup->kobj);

        return ret;
}

void btrfs_sysfs_del_qgroups(struct btrfs_fs_info *fs_info)
{
        struct btrfs_qgroup *qgroup;
        struct btrfs_qgroup *next;

        if (btrfs_is_testing(fs_info))
                return;

        rbtree_postorder_for_each_entry_safe(qgroup, next,
                                             &fs_info->qgroup_tree, node)
                btrfs_sysfs_del_one_qgroup(fs_info, qgroup);
        if (fs_info->qgroups_kobj) {
                kobject_del(fs_info->qgroups_kobj);
                kobject_put(fs_info->qgroups_kobj);
                fs_info->qgroups_kobj = NULL;
        }
}

/* Called when qgroups get initialized, thus there is no need for locking */
int btrfs_sysfs_add_qgroups(struct btrfs_fs_info *fs_info)
{
        struct kobject *fsid_kobj = &fs_info->fs_devices->fsid_kobj;
        struct btrfs_qgroup *qgroup;
        struct btrfs_qgroup *next;
        int ret = 0;

        if (btrfs_is_testing(fs_info))
                return 0;

        ASSERT(fsid_kobj);
        if (fs_info->qgroups_kobj)
                return 0;

        fs_info->qgroups_kobj = kzalloc_obj(struct kobject);
        if (!fs_info->qgroups_kobj)
                return -ENOMEM;

        ret = kobject_init_and_add(fs_info->qgroups_kobj, &qgroups_ktype,
                                   fsid_kobj, "qgroups");
        if (ret < 0)
                goto out;

        rbtree_postorder_for_each_entry_safe(qgroup, next,
                                             &fs_info->qgroup_tree, node) {
                ret = btrfs_sysfs_add_one_qgroup(fs_info, qgroup);
                if (ret < 0)
                        goto out;
        }

out:
        if (ret < 0)
                btrfs_sysfs_del_qgroups(fs_info);
        return ret;
}

void btrfs_sysfs_del_one_qgroup(struct btrfs_fs_info *fs_info,
                                struct btrfs_qgroup *qgroup)
{
        if (btrfs_is_testing(fs_info))
                return;

        if (qgroup->kobj.state_initialized) {
                kobject_del(&qgroup->kobj);
                kobject_put(&qgroup->kobj);
        }
}

/*
 * 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)
{
        struct kobject *fsid_kobj;
        int ret;

        if (!fs_info)
                return;

        fsid_kobj = &fs_info->fs_devices->fsid_kobj;
        if (!fsid_kobj->state_initialized)
                return;

        ret = sysfs_update_group(fsid_kobj, &btrfs_feature_attr_group);
        if (ret < 0)
                btrfs_warn(fs_info,
                           "failed to update /sys/fs/btrfs/%pU/features: %d",
                           fs_info->fs_devices->fsid, ret);
}

int __init btrfs_init_sysfs(void)
{
        int ret;

        btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj);
        if (!btrfs_kset)
                return -ENOMEM;

        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;

#ifdef CONFIG_BTRFS_DEBUG
        ret = sysfs_create_group(&btrfs_kset->kobj, &btrfs_debug_feature_attr_group);
        if (ret) {
                sysfs_unmerge_group(&btrfs_kset->kobj,
                                    &btrfs_static_feature_attr_group);
                goto out_remove_group;
        }
#endif

        return 0;

out_remove_group:
        sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
out2:
        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);
#ifdef CONFIG_BTRFS_DEBUG
        sysfs_remove_group(&btrfs_kset->kobj, &btrfs_debug_feature_attr_group);
#endif
        kset_unregister(btrfs_kset);
}