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Message-ID: <d057b9da-c204-511d-4ae5-4735f5f40d7f@kernel.org>
Date: Tue, 9 Nov 2021 21:14:18 +0800
From: Chao Yu <chao@...nel.org>
To: Huang Jianan <huangjianan@...o.com>, linux-erofs@...ts.ozlabs.org
Cc: zhangshiming@...o.com, linux-kernel@...r.kernel.org, yh@...o.com,
guanyuwei@...o.com, guoweichao@...o.com
Subject: Re: [PATCH v2 1/2] erofs: add sysfs interface
On 2021/11/9 15:45, Huang Jianan via Linux-erofs wrote:
> Add sysfs interface to configure erofs related parameters later.
>
> Signed-off-by: Huang Jianan <huangjianan@...o.com>
> ---
> changes since v1:
> - Add sysfs API documentation.
> - Use sysfs_emit over snprintf.
>
> Documentation/ABI/testing/sysfs-fs-erofs | 7 +
> fs/erofs/Makefile | 2 +-
> fs/erofs/internal.h | 10 +
> fs/erofs/super.c | 12 ++
> fs/erofs/sysfs.c | 237 +++++++++++++++++++++++
> 5 files changed, 267 insertions(+), 1 deletion(-)
> create mode 100644 Documentation/ABI/testing/sysfs-fs-erofs
> create mode 100644 fs/erofs/sysfs.c
>
> diff --git a/Documentation/ABI/testing/sysfs-fs-erofs b/Documentation/ABI/testing/sysfs-fs-erofs
> new file mode 100644
> index 000000000000..86d0d0234473
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-fs-erofs
> @@ -0,0 +1,7 @@
> +What: /sys/fs/erofs/features/
> +Date: November 2021
> +Contact: "Huang Jianan" <huangjianan@...o.com>
> +Description: Shows all enabled kernel features.
> + Supported features:
> + lz4_0padding, compr_cfgs, big_pcluster, device_table,
> + sb_chksum.
> diff --git a/fs/erofs/Makefile b/fs/erofs/Makefile
> index 756fe2d65272..8a3317e38e5a 100644
> --- a/fs/erofs/Makefile
> +++ b/fs/erofs/Makefile
> @@ -1,7 +1,7 @@
> # SPDX-License-Identifier: GPL-2.0-only
>
> obj-$(CONFIG_EROFS_FS) += erofs.o
> -erofs-objs := super.o inode.o data.o namei.o dir.o utils.o pcpubuf.o
> +erofs-objs := super.o inode.o data.o namei.o dir.o utils.o pcpubuf.o sysfs.o
> erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o
> erofs-$(CONFIG_EROFS_FS_ZIP) += decompressor.o zmap.o zdata.o
> erofs-$(CONFIG_EROFS_FS_ZIP_LZMA) += decompressor_lzma.o
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 3265688af7f9..d0cd712dc222 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -134,6 +134,10 @@ struct erofs_sb_info {
> u8 volume_name[16]; /* volume name */
> u32 feature_compat;
> u32 feature_incompat;
> +
> + /* sysfs support */
> + struct kobject s_kobj; /* /sys/fs/erofs/<devname> */
> + struct completion s_kobj_unregister;
> };
>
> #define EROFS_SB(sb) ((struct erofs_sb_info *)(sb)->s_fs_info)
> @@ -498,6 +502,12 @@ int erofs_pcpubuf_growsize(unsigned int nrpages);
> void erofs_pcpubuf_init(void);
> void erofs_pcpubuf_exit(void);
>
> +/* sysfs.c */
> +int erofs_register_sysfs(struct super_block *sb);
> +void erofs_unregister_sysfs(struct super_block *sb);
> +int __init erofs_init_sysfs(void);
> +void erofs_exit_sysfs(void);
> +
> /* utils.c / zdata.c */
> struct page *erofs_allocpage(struct page **pagepool, gfp_t gfp);
> static inline void erofs_pagepool_add(struct page **pagepool,
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index 6a969b1e0ee6..abc1da5d1719 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -695,6 +695,10 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
> if (err)
> return err;
>
> + err = erofs_register_sysfs(sb);
> + if (err)
> + return err;
> +
> erofs_info(sb, "mounted with root inode @ nid %llu.", ROOT_NID(sbi));
> return 0;
> }
> @@ -808,6 +812,7 @@ static void erofs_put_super(struct super_block *sb)
>
> DBG_BUGON(!sbi);
>
> + erofs_unregister_sysfs(sb);
> erofs_shrinker_unregister(sb);
> #ifdef CONFIG_EROFS_FS_ZIP
> iput(sbi->managed_cache);
> @@ -852,6 +857,10 @@ static int __init erofs_module_init(void)
> if (err)
> goto zip_err;
>
> + err = erofs_init_sysfs();
> + if (err)
> + goto sysfs_err;
> +
> err = register_filesystem(&erofs_fs_type);
> if (err)
> goto fs_err;
> @@ -859,6 +868,8 @@ static int __init erofs_module_init(void)
> return 0;
>
> fs_err:
> + erofs_exit_sysfs();
> +sysfs_err:
> z_erofs_exit_zip_subsystem();
> zip_err:
> z_erofs_lzma_exit();
> @@ -877,6 +888,7 @@ static void __exit erofs_module_exit(void)
> /* Ensure all RCU free inodes / pclusters are safe to be destroyed. */
> rcu_barrier();
>
> + erofs_exit_sysfs();
> z_erofs_exit_zip_subsystem();
> z_erofs_lzma_exit();
> erofs_exit_shrinker();
> diff --git a/fs/erofs/sysfs.c b/fs/erofs/sysfs.c
> new file mode 100644
> index 000000000000..dd328d20c451
> --- /dev/null
> +++ b/fs/erofs/sysfs.c
> @@ -0,0 +1,237 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C), 2008-2021, OPPO Mobile Comm Corp., Ltd.
> + * https://www.oppo.com/
> + */
> +#include <linux/sysfs.h>
> +#include <linux/kobject.h>
> +
> +#include "internal.h"
> +
> +enum {
> + attr_feature,
> + attr_pointer_ui,
> + attr_pointer_bool,
> +};
> +
> +enum {
> + struct_erofs_sb_info,
> +};
> +
> +struct erofs_attr {
> + struct attribute attr;
> + short attr_id;
> + int struct_type;
> + int offset;
> +};
> +
> +#define EROFS_ATTR(_name, _mode, _id) \
> +static struct erofs_attr erofs_attr_##_name = { \
> + .attr = {.name = __stringify(_name), .mode = _mode }, \
> + .attr_id = attr_##_id, \
> +}
> +#define EROFS_ATTR_FUNC(_name, _mode) EROFS_ATTR(_name, _mode, _name)
> +#define EROFS_ATTR_FEATURE(_name) EROFS_ATTR(_name, 0444, feature)
> +
> +#define EROFS_ATTR_OFFSET(_name, _mode, _id, _struct) \
> +static struct erofs_attr erofs_attr_##_name = { \
> + .attr = {.name = __stringify(_name), .mode = _mode }, \
> + .attr_id = attr_##_id, \
> + .struct_type = struct_##_struct, \
> + .offset = offsetof(struct _struct, _name),\
> +}
> +
> +#define EROFS_ATTR_RW(_name, _id, _struct) \
> + EROFS_ATTR_OFFSET(_name, 0644, _id, _struct)
> +
> +#define EROFS_RO_ATTR(_name, _id, _struct) \
> + EROFS_ATTR_OFFSET(_name, 0444, _id, _struct)
> +
> +#define EROFS_ATTR_RW_UI(_name, _struct) \
> + EROFS_ATTR_RW(_name, pointer_ui, _struct)
> +
> +#define EROFS_ATTR_RW_BOOL(_name, _struct) \
> + EROFS_ATTR_RW(_name, pointer_bool, _struct)
> +
> +#define ATTR_LIST(name) (&erofs_attr_##name.attr)
> +
> +static struct attribute *erofs_attrs[] = {
> + NULL,
> +};
> +ATTRIBUTE_GROUPS(erofs);
> +
> +/* Features this copy of erofs supports */
> +EROFS_ATTR_FEATURE(lz4_0padding);
> +EROFS_ATTR_FEATURE(compr_cfgs);
> +EROFS_ATTR_FEATURE(big_pcluster);
> +EROFS_ATTR_FEATURE(device_table);
> +EROFS_ATTR_FEATURE(sb_chksum);
> +
> +static struct attribute *erofs_feat_attrs[] = {
> + ATTR_LIST(lz4_0padding),
> + ATTR_LIST(compr_cfgs),
> + ATTR_LIST(big_pcluster),
> + ATTR_LIST(device_table),
> + ATTR_LIST(sb_chksum),
> + NULL,
> +};
> +ATTRIBUTE_GROUPS(erofs_feat);
> +
> +static unsigned char *__struct_ptr(struct erofs_sb_info *sbi,
> + int struct_type, int offset)
> +{
> + if (struct_type == struct_erofs_sb_info)
> + return (unsigned char *)sbi + offset;
> + return NULL;
> +}
> +
> +static ssize_t erofs_attr_show(struct kobject *kobj,
> + struct attribute *attr, char *buf)
> +{
> + struct erofs_sb_info *sbi = container_of(kobj, struct erofs_sb_info,
> + s_kobj);
> + struct erofs_attr *a = container_of(attr, struct erofs_attr, attr);
> + unsigned char *ptr = __struct_ptr(sbi, a->struct_type, a->offset);
> +
> + switch (a->attr_id) {
> + case attr_feature:
> + return sysfs_emit(buf, "supported\n");
> + case attr_pointer_ui:
> + if (!ptr)
> + return 0;
> + return sysfs_emit(buf, "%u\n", *(unsigned int *)ptr);
> + case attr_pointer_bool:
> + if (!ptr)
> + return 0;
> + return sysfs_emit(buf, *(bool *)ptr ? "true\n" : "false\n");
Is it fine to just print 1 or 0 like the value user set via the sysfs entry
to indicate true or false.
> + }
> +
> + return 0;
> +}
> +
> +static ssize_t erofs_attr_store(struct kobject *kobj, struct attribute *attr,
> + const char *buf, size_t len)
> +{
> + struct erofs_sb_info *sbi = container_of(kobj, struct erofs_sb_info,
> + s_kobj);
> + struct erofs_attr *a = container_of(attr, struct erofs_attr, attr);
> + unsigned char *ptr = __struct_ptr(sbi, a->struct_type, a->offset);
> + unsigned long t;
> + int ret;
> +
> + switch (a->attr_id) {
> + case attr_pointer_ui:
> + if (!ptr)
> + return 0;
> + ret = kstrtoul(skip_spaces(buf), 0, &t);
> + if (ret)
> + return ret;
if (t > UINT_MAX)
return -EINVAL;
> + *((unsigned int *) ptr) = t;
> + return len;
> + case attr_pointer_bool:
> + if (!ptr)
> + return 0;
> + ret = kstrtoul(skip_spaces(buf), 0, &t);
> + if (ret)
> + return ret;
@t should be 0 or 1?
if (t != 0 && t != 1)
return -EINVAL;
Thanks,
> + *((bool *) ptr) = !!t;
> + return len;
> + }
> +
> + return 0;
> +}
> +
> +static void erofs_sb_release(struct kobject *kobj)
> +{
> + struct erofs_sb_info *sbi = container_of(kobj, struct erofs_sb_info,
> + s_kobj);
> + complete(&sbi->s_kobj_unregister);
> +}
> +
> +static const struct sysfs_ops erofs_attr_ops = {
> + .show = erofs_attr_show,
> + .store = erofs_attr_store,
> +};
> +
> +static struct kobj_type erofs_sb_ktype = {
> + .default_groups = erofs_groups,
> + .sysfs_ops = &erofs_attr_ops,
> + .release = erofs_sb_release,
> +};
> +
> +static struct kobj_type erofs_ktype = {
> + .sysfs_ops = &erofs_attr_ops,
> +};
> +
> +static struct kset erofs_root = {
> + .kobj = {.ktype = &erofs_ktype},
> +};
> +
> +static struct kobj_type erofs_feat_ktype = {
> + .default_groups = erofs_feat_groups,
> + .sysfs_ops = &erofs_attr_ops,
> +};
> +
> +static struct kobject erofs_feat = {
> + .kset = &erofs_root,
> +};
> +
> +int erofs_register_sysfs(struct super_block *sb)
> +{
> + struct erofs_sb_info *sbi = EROFS_SB(sb);
> + int err;
> +
> + sbi->s_kobj.kset = &erofs_root;
> + init_completion(&sbi->s_kobj_unregister);
> + err = kobject_init_and_add(&sbi->s_kobj, &erofs_sb_ktype, NULL,
> + "%s", sb->s_id);
> + if (err)
> + goto put_sb_kobj;
> +
> + return 0;
> +
> +put_sb_kobj:
> + kobject_put(&sbi->s_kobj);
> + wait_for_completion(&sbi->s_kobj_unregister);
> + return err;
> +}
> +
> +void erofs_unregister_sysfs(struct super_block *sb)
> +{
> + struct erofs_sb_info *sbi = EROFS_SB(sb);
> +
> + kobject_del(&sbi->s_kobj);
> + kobject_put(&sbi->s_kobj);
> + wait_for_completion(&sbi->s_kobj_unregister);
> +}
> +
> +int __init erofs_init_sysfs(void)
> +{
> + int ret;
> +
> + kobject_set_name(&erofs_root.kobj, "erofs");
> + erofs_root.kobj.parent = fs_kobj;
> + ret = kset_register(&erofs_root);
> + if (ret)
> + goto root_err;
> +
> + ret = kobject_init_and_add(&erofs_feat, &erofs_feat_ktype,
> + NULL, "features");
> + if (ret)
> + goto feat_err;
> +
> + return ret;
> +
> +feat_err:
> + kobject_put(&erofs_feat);
> + kset_unregister(&erofs_root);
> +root_err:
> + return ret;
> +}
> +
> +void erofs_exit_sysfs(void)
> +{
> + kobject_put(&erofs_feat);
> + kset_unregister(&erofs_root);
> +}
> +
>
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