linux/fs/ext4/sysfs.c
Kees Cook 118901ad1f ext4: Fix function prototype mismatch for ext4_feat_ktype
With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
indirect call targets are validated against the expected function
pointer prototype to make sure the call target is valid to help mitigate
ROP attacks. If they are not identical, there is a failure at run time,
which manifests as either a kernel panic or thread getting killed.

ext4_feat_ktype was setting the "release" handler to "kfree", which
doesn't have a matching function prototype. Add a simple wrapper
with the correct prototype.

This was found as a result of Clang's new -Wcast-function-type-strict
flag, which is more sensitive than the simpler -Wcast-function-type,
which only checks for type width mismatches.

Note that this code is only reached when ext4 is a loadable module and
it is being unloaded:

 CFI failure at kobject_put+0xbb/0x1b0 (target: kfree+0x0/0x180; expected type: 0x7c4aa698)
 ...
 RIP: 0010:kobject_put+0xbb/0x1b0
 ...
 Call Trace:
  <TASK>
  ext4_exit_sysfs+0x14/0x60 [ext4]
  cleanup_module+0x67/0xedb [ext4]

Fixes: b99fee58a2 ("ext4: create ext4_feat kobject dynamically")
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: stable@vger.kernel.org
Build-tested-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20230103234616.never.915-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20230104210908.gonna.388-kees@kernel.org
2023-01-27 11:42:56 -08:00

609 lines
17 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/ext4/sysfs.c
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card (card@masi.ibp.fr)
* Theodore Ts'o (tytso@mit.edu)
*
*/
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/proc_fs.h>
#include <linux/part_stat.h>
#include "ext4.h"
#include "ext4_jbd2.h"
typedef enum {
attr_noop,
attr_delayed_allocation_blocks,
attr_session_write_kbytes,
attr_lifetime_write_kbytes,
attr_reserved_clusters,
attr_sra_exceeded_retry_limit,
attr_inode_readahead,
attr_trigger_test_error,
attr_first_error_time,
attr_last_error_time,
attr_feature,
attr_pointer_ui,
attr_pointer_ul,
attr_pointer_u64,
attr_pointer_u8,
attr_pointer_string,
attr_pointer_atomic,
attr_journal_task,
} attr_id_t;
typedef enum {
ptr_explicit,
ptr_ext4_sb_info_offset,
ptr_ext4_super_block_offset,
} attr_ptr_t;
static const char proc_dirname[] = "fs/ext4";
static struct proc_dir_entry *ext4_proc_root;
struct ext4_attr {
struct attribute attr;
short attr_id;
short attr_ptr;
unsigned short attr_size;
union {
int offset;
void *explicit_ptr;
} u;
};
static ssize_t session_write_kbytes_show(struct ext4_sb_info *sbi, char *buf)
{
struct super_block *sb = sbi->s_buddy_cache->i_sb;
return sysfs_emit(buf, "%lu\n",
(part_stat_read(sb->s_bdev, sectors[STAT_WRITE]) -
sbi->s_sectors_written_start) >> 1);
}
static ssize_t lifetime_write_kbytes_show(struct ext4_sb_info *sbi, char *buf)
{
struct super_block *sb = sbi->s_buddy_cache->i_sb;
return sysfs_emit(buf, "%llu\n",
(unsigned long long)(sbi->s_kbytes_written +
((part_stat_read(sb->s_bdev, sectors[STAT_WRITE]) -
EXT4_SB(sb)->s_sectors_written_start) >> 1)));
}
static ssize_t inode_readahead_blks_store(struct ext4_sb_info *sbi,
const char *buf, size_t count)
{
unsigned long t;
int ret;
ret = kstrtoul(skip_spaces(buf), 0, &t);
if (ret)
return ret;
if (t && (!is_power_of_2(t) || t > 0x40000000))
return -EINVAL;
sbi->s_inode_readahead_blks = t;
return count;
}
static ssize_t reserved_clusters_store(struct ext4_sb_info *sbi,
const char *buf, size_t count)
{
unsigned long long val;
ext4_fsblk_t clusters = (ext4_blocks_count(sbi->s_es) >>
sbi->s_cluster_bits);
int ret;
ret = kstrtoull(skip_spaces(buf), 0, &val);
if (ret || val >= clusters)
return -EINVAL;
atomic64_set(&sbi->s_resv_clusters, val);
return count;
}
static ssize_t trigger_test_error(struct ext4_sb_info *sbi,
const char *buf, size_t count)
{
int len = count;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (len && buf[len-1] == '\n')
len--;
if (len)
ext4_error(sbi->s_sb, "%.*s", len, buf);
return count;
}
static ssize_t journal_task_show(struct ext4_sb_info *sbi, char *buf)
{
if (!sbi->s_journal)
return sysfs_emit(buf, "<none>\n");
return sysfs_emit(buf, "%d\n",
task_pid_vnr(sbi->s_journal->j_task));
}
#define EXT4_ATTR(_name,_mode,_id) \
static struct ext4_attr ext4_attr_##_name = { \
.attr = {.name = __stringify(_name), .mode = _mode }, \
.attr_id = attr_##_id, \
}
#define EXT4_ATTR_FUNC(_name,_mode) EXT4_ATTR(_name,_mode,_name)
#define EXT4_ATTR_FEATURE(_name) EXT4_ATTR(_name, 0444, feature)
#define EXT4_ATTR_OFFSET(_name,_mode,_id,_struct,_elname) \
static struct ext4_attr ext4_attr_##_name = { \
.attr = {.name = __stringify(_name), .mode = _mode }, \
.attr_id = attr_##_id, \
.attr_ptr = ptr_##_struct##_offset, \
.u = { \
.offset = offsetof(struct _struct, _elname),\
}, \
}
#define EXT4_ATTR_STRING(_name,_mode,_size,_struct,_elname) \
static struct ext4_attr ext4_attr_##_name = { \
.attr = {.name = __stringify(_name), .mode = _mode }, \
.attr_id = attr_pointer_string, \
.attr_size = _size, \
.attr_ptr = ptr_##_struct##_offset, \
.u = { \
.offset = offsetof(struct _struct, _elname),\
}, \
}
#define EXT4_RO_ATTR_ES_UI(_name,_elname) \
EXT4_ATTR_OFFSET(_name, 0444, pointer_ui, ext4_super_block, _elname)
#define EXT4_RO_ATTR_ES_U8(_name,_elname) \
EXT4_ATTR_OFFSET(_name, 0444, pointer_u8, ext4_super_block, _elname)
#define EXT4_RO_ATTR_ES_U64(_name,_elname) \
EXT4_ATTR_OFFSET(_name, 0444, pointer_u64, ext4_super_block, _elname)
#define EXT4_RO_ATTR_ES_STRING(_name,_elname,_size) \
EXT4_ATTR_STRING(_name, 0444, _size, ext4_super_block, _elname)
#define EXT4_RW_ATTR_SBI_UI(_name,_elname) \
EXT4_ATTR_OFFSET(_name, 0644, pointer_ui, ext4_sb_info, _elname)
#define EXT4_RW_ATTR_SBI_UL(_name,_elname) \
EXT4_ATTR_OFFSET(_name, 0644, pointer_ul, ext4_sb_info, _elname)
#define EXT4_RO_ATTR_SBI_ATOMIC(_name,_elname) \
EXT4_ATTR_OFFSET(_name, 0444, pointer_atomic, ext4_sb_info, _elname)
#define EXT4_ATTR_PTR(_name,_mode,_id,_ptr) \
static struct ext4_attr ext4_attr_##_name = { \
.attr = {.name = __stringify(_name), .mode = _mode }, \
.attr_id = attr_##_id, \
.attr_ptr = ptr_explicit, \
.u = { \
.explicit_ptr = _ptr, \
}, \
}
#define ATTR_LIST(name) &ext4_attr_##name.attr
EXT4_ATTR_FUNC(delayed_allocation_blocks, 0444);
EXT4_ATTR_FUNC(session_write_kbytes, 0444);
EXT4_ATTR_FUNC(lifetime_write_kbytes, 0444);
EXT4_ATTR_FUNC(reserved_clusters, 0644);
EXT4_ATTR_FUNC(sra_exceeded_retry_limit, 0444);
EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead,
ext4_sb_info, s_inode_readahead_blks);
EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal);
EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats);
EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);
EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan);
EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
EXT4_RW_ATTR_SBI_UI(mb_max_inode_prealloc, s_mb_max_inode_prealloc);
EXT4_RW_ATTR_SBI_UI(mb_max_linear_groups, s_mb_max_linear_groups);
EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error);
EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
EXT4_RW_ATTR_SBI_UI(err_ratelimit_burst, s_err_ratelimit_state.burst);
EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval);
EXT4_RW_ATTR_SBI_UI(warning_ratelimit_burst, s_warning_ratelimit_state.burst);
EXT4_RW_ATTR_SBI_UI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval);
EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst);
#ifdef CONFIG_EXT4_DEBUG
EXT4_RW_ATTR_SBI_UL(simulate_fail, s_simulate_fail);
#endif
EXT4_RO_ATTR_SBI_ATOMIC(warning_count, s_warning_count);
EXT4_RO_ATTR_SBI_ATOMIC(msg_count, s_msg_count);
EXT4_RO_ATTR_ES_UI(errors_count, s_error_count);
EXT4_RO_ATTR_ES_U8(first_error_errcode, s_first_error_errcode);
EXT4_RO_ATTR_ES_U8(last_error_errcode, s_last_error_errcode);
EXT4_RO_ATTR_ES_UI(first_error_ino, s_first_error_ino);
EXT4_RO_ATTR_ES_UI(last_error_ino, s_last_error_ino);
EXT4_RO_ATTR_ES_U64(first_error_block, s_first_error_block);
EXT4_RO_ATTR_ES_U64(last_error_block, s_last_error_block);
EXT4_RO_ATTR_ES_UI(first_error_line, s_first_error_line);
EXT4_RO_ATTR_ES_UI(last_error_line, s_last_error_line);
EXT4_RO_ATTR_ES_STRING(first_error_func, s_first_error_func, 32);
EXT4_RO_ATTR_ES_STRING(last_error_func, s_last_error_func, 32);
EXT4_ATTR(first_error_time, 0444, first_error_time);
EXT4_ATTR(last_error_time, 0444, last_error_time);
EXT4_ATTR(journal_task, 0444, journal_task);
EXT4_RW_ATTR_SBI_UI(mb_prefetch, s_mb_prefetch);
EXT4_RW_ATTR_SBI_UI(mb_prefetch_limit, s_mb_prefetch_limit);
EXT4_RW_ATTR_SBI_UL(last_trim_minblks, s_last_trim_minblks);
static unsigned int old_bump_val = 128;
EXT4_ATTR_PTR(max_writeback_mb_bump, 0444, pointer_ui, &old_bump_val);
static struct attribute *ext4_attrs[] = {
ATTR_LIST(delayed_allocation_blocks),
ATTR_LIST(session_write_kbytes),
ATTR_LIST(lifetime_write_kbytes),
ATTR_LIST(reserved_clusters),
ATTR_LIST(sra_exceeded_retry_limit),
ATTR_LIST(inode_readahead_blks),
ATTR_LIST(inode_goal),
ATTR_LIST(mb_stats),
ATTR_LIST(mb_max_to_scan),
ATTR_LIST(mb_min_to_scan),
ATTR_LIST(mb_order2_req),
ATTR_LIST(mb_stream_req),
ATTR_LIST(mb_group_prealloc),
ATTR_LIST(mb_max_inode_prealloc),
ATTR_LIST(mb_max_linear_groups),
ATTR_LIST(max_writeback_mb_bump),
ATTR_LIST(extent_max_zeroout_kb),
ATTR_LIST(trigger_fs_error),
ATTR_LIST(err_ratelimit_interval_ms),
ATTR_LIST(err_ratelimit_burst),
ATTR_LIST(warning_ratelimit_interval_ms),
ATTR_LIST(warning_ratelimit_burst),
ATTR_LIST(msg_ratelimit_interval_ms),
ATTR_LIST(msg_ratelimit_burst),
ATTR_LIST(errors_count),
ATTR_LIST(warning_count),
ATTR_LIST(msg_count),
ATTR_LIST(first_error_ino),
ATTR_LIST(last_error_ino),
ATTR_LIST(first_error_block),
ATTR_LIST(last_error_block),
ATTR_LIST(first_error_line),
ATTR_LIST(last_error_line),
ATTR_LIST(first_error_func),
ATTR_LIST(last_error_func),
ATTR_LIST(first_error_errcode),
ATTR_LIST(last_error_errcode),
ATTR_LIST(first_error_time),
ATTR_LIST(last_error_time),
ATTR_LIST(journal_task),
#ifdef CONFIG_EXT4_DEBUG
ATTR_LIST(simulate_fail),
#endif
ATTR_LIST(mb_prefetch),
ATTR_LIST(mb_prefetch_limit),
ATTR_LIST(last_trim_minblks),
NULL,
};
ATTRIBUTE_GROUPS(ext4);
/* Features this copy of ext4 supports */
EXT4_ATTR_FEATURE(lazy_itable_init);
EXT4_ATTR_FEATURE(batched_discard);
EXT4_ATTR_FEATURE(meta_bg_resize);
#ifdef CONFIG_FS_ENCRYPTION
EXT4_ATTR_FEATURE(encryption);
EXT4_ATTR_FEATURE(test_dummy_encryption_v2);
#endif
#if IS_ENABLED(CONFIG_UNICODE)
EXT4_ATTR_FEATURE(casefold);
#endif
#ifdef CONFIG_FS_VERITY
EXT4_ATTR_FEATURE(verity);
#endif
EXT4_ATTR_FEATURE(metadata_csum_seed);
EXT4_ATTR_FEATURE(fast_commit);
#if IS_ENABLED(CONFIG_UNICODE) && defined(CONFIG_FS_ENCRYPTION)
EXT4_ATTR_FEATURE(encrypted_casefold);
#endif
static struct attribute *ext4_feat_attrs[] = {
ATTR_LIST(lazy_itable_init),
ATTR_LIST(batched_discard),
ATTR_LIST(meta_bg_resize),
#ifdef CONFIG_FS_ENCRYPTION
ATTR_LIST(encryption),
ATTR_LIST(test_dummy_encryption_v2),
#endif
#if IS_ENABLED(CONFIG_UNICODE)
ATTR_LIST(casefold),
#endif
#ifdef CONFIG_FS_VERITY
ATTR_LIST(verity),
#endif
ATTR_LIST(metadata_csum_seed),
ATTR_LIST(fast_commit),
#if IS_ENABLED(CONFIG_UNICODE) && defined(CONFIG_FS_ENCRYPTION)
ATTR_LIST(encrypted_casefold),
#endif
NULL,
};
ATTRIBUTE_GROUPS(ext4_feat);
static void *calc_ptr(struct ext4_attr *a, struct ext4_sb_info *sbi)
{
switch (a->attr_ptr) {
case ptr_explicit:
return a->u.explicit_ptr;
case ptr_ext4_sb_info_offset:
return (void *) (((char *) sbi) + a->u.offset);
case ptr_ext4_super_block_offset:
return (void *) (((char *) sbi->s_es) + a->u.offset);
}
return NULL;
}
static ssize_t __print_tstamp(char *buf, __le32 lo, __u8 hi)
{
return sysfs_emit(buf, "%lld\n",
((time64_t)hi << 32) + le32_to_cpu(lo));
}
#define print_tstamp(buf, es, tstamp) \
__print_tstamp(buf, (es)->tstamp, (es)->tstamp ## _hi)
static ssize_t ext4_attr_show(struct kobject *kobj,
struct attribute *attr, char *buf)
{
struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
s_kobj);
struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);
void *ptr = calc_ptr(a, sbi);
switch (a->attr_id) {
case attr_delayed_allocation_blocks:
return sysfs_emit(buf, "%llu\n",
(s64) EXT4_C2B(sbi,
percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
case attr_session_write_kbytes:
return session_write_kbytes_show(sbi, buf);
case attr_lifetime_write_kbytes:
return lifetime_write_kbytes_show(sbi, buf);
case attr_reserved_clusters:
return sysfs_emit(buf, "%llu\n",
(unsigned long long)
atomic64_read(&sbi->s_resv_clusters));
case attr_sra_exceeded_retry_limit:
return sysfs_emit(buf, "%llu\n",
(unsigned long long)
percpu_counter_sum(&sbi->s_sra_exceeded_retry_limit));
case attr_inode_readahead:
case attr_pointer_ui:
if (!ptr)
return 0;
if (a->attr_ptr == ptr_ext4_super_block_offset)
return sysfs_emit(buf, "%u\n",
le32_to_cpup(ptr));
else
return sysfs_emit(buf, "%u\n",
*((unsigned int *) ptr));
case attr_pointer_ul:
if (!ptr)
return 0;
return sysfs_emit(buf, "%lu\n",
*((unsigned long *) ptr));
case attr_pointer_u8:
if (!ptr)
return 0;
return sysfs_emit(buf, "%u\n",
*((unsigned char *) ptr));
case attr_pointer_u64:
if (!ptr)
return 0;
if (a->attr_ptr == ptr_ext4_super_block_offset)
return sysfs_emit(buf, "%llu\n",
le64_to_cpup(ptr));
else
return sysfs_emit(buf, "%llu\n",
*((unsigned long long *) ptr));
case attr_pointer_string:
if (!ptr)
return 0;
return sysfs_emit(buf, "%.*s\n", a->attr_size,
(char *) ptr);
case attr_pointer_atomic:
if (!ptr)
return 0;
return sysfs_emit(buf, "%d\n",
atomic_read((atomic_t *) ptr));
case attr_feature:
return sysfs_emit(buf, "supported\n");
case attr_first_error_time:
return print_tstamp(buf, sbi->s_es, s_first_error_time);
case attr_last_error_time:
return print_tstamp(buf, sbi->s_es, s_last_error_time);
case attr_journal_task:
return journal_task_show(sbi, buf);
}
return 0;
}
static ssize_t ext4_attr_store(struct kobject *kobj,
struct attribute *attr,
const char *buf, size_t len)
{
struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
s_kobj);
struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);
void *ptr = calc_ptr(a, sbi);
unsigned long t;
int ret;
switch (a->attr_id) {
case attr_reserved_clusters:
return reserved_clusters_store(sbi, buf, len);
case attr_pointer_ui:
if (!ptr)
return 0;
ret = kstrtoul(skip_spaces(buf), 0, &t);
if (ret)
return ret;
if (a->attr_ptr == ptr_ext4_super_block_offset)
*((__le32 *) ptr) = cpu_to_le32(t);
else
*((unsigned int *) ptr) = t;
return len;
case attr_pointer_ul:
if (!ptr)
return 0;
ret = kstrtoul(skip_spaces(buf), 0, &t);
if (ret)
return ret;
*((unsigned long *) ptr) = t;
return len;
case attr_inode_readahead:
return inode_readahead_blks_store(sbi, buf, len);
case attr_trigger_test_error:
return trigger_test_error(sbi, buf, len);
}
return 0;
}
static void ext4_sb_release(struct kobject *kobj)
{
struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
s_kobj);
complete(&sbi->s_kobj_unregister);
}
static void ext4_feat_release(struct kobject *kobj)
{
kfree(kobj);
}
static const struct sysfs_ops ext4_attr_ops = {
.show = ext4_attr_show,
.store = ext4_attr_store,
};
static struct kobj_type ext4_sb_ktype = {
.default_groups = ext4_groups,
.sysfs_ops = &ext4_attr_ops,
.release = ext4_sb_release,
};
static struct kobj_type ext4_feat_ktype = {
.default_groups = ext4_feat_groups,
.sysfs_ops = &ext4_attr_ops,
.release = ext4_feat_release,
};
void ext4_notify_error_sysfs(struct ext4_sb_info *sbi)
{
sysfs_notify(&sbi->s_kobj, NULL, "errors_count");
}
static struct kobject *ext4_root;
static struct kobject *ext4_feat;
int ext4_register_sysfs(struct super_block *sb)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
int err;
init_completion(&sbi->s_kobj_unregister);
err = kobject_init_and_add(&sbi->s_kobj, &ext4_sb_ktype, ext4_root,
"%s", sb->s_id);
if (err) {
kobject_put(&sbi->s_kobj);
wait_for_completion(&sbi->s_kobj_unregister);
return err;
}
if (ext4_proc_root)
sbi->s_proc = proc_mkdir(sb->s_id, ext4_proc_root);
if (sbi->s_proc) {
proc_create_single_data("options", S_IRUGO, sbi->s_proc,
ext4_seq_options_show, sb);
proc_create_single_data("es_shrinker_info", S_IRUGO,
sbi->s_proc, ext4_seq_es_shrinker_info_show,
sb);
proc_create_single_data("fc_info", 0444, sbi->s_proc,
ext4_fc_info_show, sb);
proc_create_seq_data("mb_groups", S_IRUGO, sbi->s_proc,
&ext4_mb_seq_groups_ops, sb);
proc_create_single_data("mb_stats", 0444, sbi->s_proc,
ext4_seq_mb_stats_show, sb);
proc_create_seq_data("mb_structs_summary", 0444, sbi->s_proc,
&ext4_mb_seq_structs_summary_ops, sb);
}
return 0;
}
void ext4_unregister_sysfs(struct super_block *sb)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
if (sbi->s_proc)
remove_proc_subtree(sb->s_id, ext4_proc_root);
kobject_del(&sbi->s_kobj);
}
int __init ext4_init_sysfs(void)
{
int ret;
ext4_root = kobject_create_and_add("ext4", fs_kobj);
if (!ext4_root)
return -ENOMEM;
ext4_feat = kzalloc(sizeof(*ext4_feat), GFP_KERNEL);
if (!ext4_feat) {
ret = -ENOMEM;
goto root_err;
}
ret = kobject_init_and_add(ext4_feat, &ext4_feat_ktype,
ext4_root, "features");
if (ret)
goto feat_err;
ext4_proc_root = proc_mkdir(proc_dirname, NULL);
return ret;
feat_err:
kobject_put(ext4_feat);
ext4_feat = NULL;
root_err:
kobject_put(ext4_root);
ext4_root = NULL;
return ret;
}
void ext4_exit_sysfs(void)
{
kobject_put(ext4_feat);
ext4_feat = NULL;
kobject_put(ext4_root);
ext4_root = NULL;
remove_proc_entry(proc_dirname, NULL);
ext4_proc_root = NULL;
}