>
> Regards,
> Mark
>
> On Wed, Aug 27, 2008 at 6:18 PM, Benjamin Thery <benjamin.thery@bull.net> wrote:
>> Eric W. Biederman wrote:
>>> The problem. When implementing a network namespace I need to be able
>>> to have multiple network devices with the same name. Currently this
>>> is a problem for /sys/class/net/*, /sys/devices/virtual/net/*, and
>>> potentially a few other directories of the form /sys/ ... /net/*.
>>>
>>> What this patch does is to add an additional tag field to the
>>> sysfs dirent structure. For directories that should show different
>>> contents depending on the context such as /sys/class/net/, and
>>> /sys/devices/virtual/net/ this tag field is used to specify the
>>> context in which those directories should be visible. Effectively
>>> this is the same as creating multiple distinct directories with
>>> the same name but internally to sysfs the result is nicer.
>>>
>>> I am calling the concept of a single directory that looks like multiple
>>> directories all at the same path in the filesystem tagged directories.
>>>
>>> For the networking namespace the set of directories whose contents I need
>>> to filter with tags can depend on the presence or absence of hotplug
>>> hardware or which modules are currently loaded. Which means I need
>>> a simple race free way to setup those directories as tagged.
>>>
>>> To achieve a reace free design all tagged directories are created
>>> and managed by sysfs itself.
>>>
>>> Users of this interface:
>>> - define a type in the sysfs_tag_type enumeration.
>>> - call sysfs_register_tag_types with the type and it's operations
>>> - call sysfs_make_tagged_dir with the tag type on directories
>>> to be managed by this tag type
>>> - sysfs_exit_tag when an individual tag is no longer valid
>>>
>>> - Implement mount_tag() which returns the tag of the calling process
>>> so we can attach it to a sysfs superblock.
>>> - Implement ktype.sysfs_tag() which returns the tag of a syfs kobject.
>>>
>>> Everything else is left up to sysfs and the driver layer.
>>>
>>> For the network namespace mount_tag and sysfs_tag are essentially
>>> one line functions, and look to remain that.
>>>
>>> Tags are currently represented a const void * pointers as that is
>>> both generic, prevides enough information for equality comparisons,
>>> and is trivial to create for current users, as it is just the
>>> existing namespace pointer.
>>>
>>> The work needed in sysfs is more extensive. At each directory
>>> or symlink creating I need to check if the directory it is being
>>> created in is a tagged directory and if so generate the appropriate
>>> tag to place on the sysfs_dirent. Likewise at each symlink or
>>> directory removal I need to check if the sysfs directory it is
>>> being removed from is a tagged directory and if so figure out
>>> which tag goes along with the name I am deleting.
>>>
>>> Currently only directories which hold kobjects, and
>>> symlinks are supported. There is not enough information
>>> in the current file attribute interfaces to give us anything
>>> to discriminate on which makes it useless, and there are
>>> no potential users which makes it an uninteresting problem
>>> to solve.
>>>
>>> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
>>> Signed-off-by: Benjamin Thery <benjamin.thery@bull.net>
>>> ---
>>> fs/sysfs/bin.c | 2 +-
>>> fs/sysfs/dir.c | 139
>>> ++++++++++++++++++++++++++++++++++++++++++-----
>>> fs/sysfs/file.c | 11 +++--
>>> fs/sysfs/group.c | 4 +-
>>> fs/sysfs/inode.c | 7 ++-
>>> fs/sysfs/mount.c | 115 +++++++++++++++++++++++++++++++++++++--
>>> fs/sysfs/symlink.c | 2 +-
>>> fs/sysfs/sysfs.h | 19 ++++++-
>>> include/linux/kobject.h | 1 +
>>> include/linux/sysfs.h | 31 +++++++++++
>>> 10 files changed, 298 insertions(+), 33 deletions(-)
>>>
>>> diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
>>> index 006fc64..86e1128 100644
>>> --- a/fs/sysfs/bin.c
>>> +++ b/fs/sysfs/bin.c
>>> @@ -252,7 +252,7 @@ int sysfs_create_bin_file(struct kobject * kobj,
>>> struct bin_attribute * attr)
>>> void sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute *
>>> attr)
>>> {
>>> - sysfs_hash_and_remove(kobj->sd, attr->attr.name);
>>> + sysfs_hash_and_remove(kobj, kobj->sd, attr->attr.name);
>>> }
>>> EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
>>> diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
>>> index 4ffcfd2..dec7586 100644
>>> --- a/fs/sysfs/dir.c
>>> +++ b/fs/sysfs/dir.c
>>> @@ -30,6 +30,30 @@ DEFINE_SPINLOCK(sysfs_assoc_lock);
>>> static DEFINE_SPINLOCK(sysfs_ino_lock);
>>> static DEFINE_IDA(sysfs_ino_ida);
>>> +static const void *sysfs_creation_tag(struct sysfs_dirent *parent_sd,
>>> + struct sysfs_dirent *sd)
>>> +{
>>> + const void *tag = NULL;
>>> +
>>> + if (sysfs_tag_type(parent_sd)) {
>>> + struct kobject *kobj;
>>> + switch (sysfs_type(sd)) {
>>> + case SYSFS_DIR:
>>> + kobj = sd->s_dir.kobj;
>>> + break;
>>> + case SYSFS_KOBJ_LINK:
>>> + kobj = sd->s_symlink.target_sd->s_dir.kobj;
>>> + break;
>>> + default:
>>> + BUG();
>>> + }
>>> + tag = kobj->ktype->sysfs_tag(kobj);
>>> + /* NULL tags are reserved for internal use */
>>> + BUG_ON(tag == NULL);
>>> + }
>>> + return tag;
>>> +}
>>> +
>>> /**
>>> * sysfs_link_sibling - link sysfs_dirent into sibling list
>>> * @sd: sysfs_dirent of interest
>>> @@ -101,8 +125,19 @@ static void sysfs_unlink_sibling(struct sysfs_dirent
>>> *sd)
>>> struct dentry *sysfs_get_dentry(struct super_block *sb,
>>> struct sysfs_dirent *sd)
>>> {
>>> - struct dentry *dentry = dget(sb->s_root);
>>> + struct dentry *dentry;
>>> +
>>> + /* Bail if this sd won't show up in this superblock */
>>> + if (sd->s_parent) {
>>> + enum sysfs_tag_type type;
>>> + const void *tag;
>>> + type = sysfs_tag_type(sd->s_parent);
>>> + tag = sysfs_info(sb)->tag[type];
>>> + if (sd->s_tag != tag)
>>> + return ERR_PTR(-EXDEV);
>>> + }
>>> + dentry = dget(sb->s_root);
>>> while (dentry->d_fsdata != sd) {
>>> struct sysfs_dirent *cur;
>>> struct dentry *parent;
>>> @@ -421,10 +456,15 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
>>> */
>>> int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent
>>> *sd)
>>> {
>>> - if (sysfs_find_dirent(acxt->parent_sd, sd->s_name))
>>> + const void *tag = NULL;
>>> +
>>> + tag = sysfs_creation_tag(acxt->parent_sd, sd);
>>> +
>>> + if (sysfs_find_dirent(acxt->parent_sd, tag, sd->s_name))
>>> return -EEXIST;
>>> sd->s_parent = sysfs_get(acxt->parent_sd);
>>> + sd->s_tag = tag;
>>> if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
>>> inc_nlink(acxt->parent_inode);
>>> @@ -602,13 +642,17 @@ void sysfs_addrm_finish(struct sysfs_addrm_cxt
>>> *acxt)
>>> * Pointer to sysfs_dirent if found, NULL if not.
>>> */
>>> struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
>>> + const void *tag,
>>> const unsigned char *name)
>>> {
>>> struct sysfs_dirent *sd;
>>> - for (sd = parent_sd->s_dir.children; sd; sd = sd->s_sibling)
>>> + for (sd = parent_sd->s_dir.children; sd; sd = sd->s_sibling) {
>>> + if (sd->s_tag != tag)
>>> + continue;
>>> if (!strcmp(sd->s_name, name))
>>> return sd;
>>> + }
>>> return NULL;
>>> }
>>> @@ -632,7 +676,7 @@ struct sysfs_dirent *sysfs_get_dirent(struct
>>> sysfs_dirent *parent_sd,
>>> struct sysfs_dirent *sd;
>>> mutex_lock(&sysfs_mutex);
>>> - sd = sysfs_find_dirent(parent_sd, name);
>>> + sd = sysfs_find_dirent(parent_sd, NULL, name);
>>> sysfs_get(sd);
>>> mutex_unlock(&sysfs_mutex);
>>> @@ -699,13 +743,18 @@ static struct dentry * sysfs_lookup(struct inode
>>> *dir, struct dentry *dentry,
>>> struct nameidata *nd)
>>> {
>>> struct dentry *ret = NULL;
>>> - struct sysfs_dirent *parent_sd = dentry->d_parent->d_fsdata;
>>> + struct dentry *parent = dentry->d_parent;
>>> + struct sysfs_dirent *parent_sd = parent->d_fsdata;
>>> struct sysfs_dirent *sd;
>>> struct inode *inode;
>>> + enum sysfs_tag_type type;
>>> + const void *tag;
>>> mutex_lock(&sysfs_mutex);
>>> - sd = sysfs_find_dirent(parent_sd, dentry->d_name.name);
>>> + type = sysfs_tag_type(parent_sd);
>>> + tag = sysfs_info(parent->d_sb)->tag[type];
>>> + sd = sysfs_find_dirent(parent_sd, tag, dentry->d_name.name);
>>> /* no such entry */
>>> if (!sd) {
>>> @@ -913,19 +962,24 @@ int sysfs_rename_dir(struct kobject * kobj, const
>>> char *new_name)
>>> struct sysfs_rename_struct *srs;
>>> struct inode *parent_inode = NULL;
>>> const char *dup_name = NULL;
>>> + const void *old_tag, *tag;
>>> int error;
>>> INIT_LIST_HEAD(&todo);
>>> mutex_lock(&sysfs_rename_mutex);
>>> + old_tag = sd->s_tag;
>>> + tag = sysfs_creation_tag(sd->s_parent, sd);
>>> error = 0;
>>> - if (strcmp(sd->s_name, new_name) == 0)
>>> + if ((old_tag == tag) && (strcmp(sd->s_name, new_name) == 0))
>>> goto out; /* nothing to rename */
>>> sysfs_grab_supers();
>>> - error = prep_rename(&todo, sd, sd->s_parent, new_name);
>>> - if (error)
>>> - goto out_release;
>>> + if (old_tag == tag) {
>>> + error = prep_rename(&todo, sd, sd->s_parent, new_name);
>>> + if (error)
>>> + goto out_release;
>>> + }
>>> error = -ENOMEM;
>>> mutex_lock(&sysfs_mutex);
>>> @@ -938,7 +992,7 @@ int sysfs_rename_dir(struct kobject * kobj, const char
>>> *new_name)
>>> mutex_lock(&sysfs_mutex);
>>> error = -EEXIST;
>>> - if (sysfs_find_dirent(sd->s_parent, new_name))
>>> + if (sysfs_find_dirent(sd->s_parent, tag, new_name))
>>> goto out_unlock;
>>> /* rename sysfs_dirent */
>>> @@ -949,6 +1003,7 @@ int sysfs_rename_dir(struct kobject * kobj, const
>>> char *new_name)
>>> dup_name = sd->s_name;
>>> sd->s_name = new_name;
>>> + sd->s_tag = tag;
>>> /* rename */
>>> list_for_each_entry(srs, &todo, list) {
>>> @@ -956,6 +1011,20 @@ int sysfs_rename_dir(struct kobject * kobj, const
>>> char *new_name)
>>> d_move(srs->old_dentry, srs->new_dentry);
>>> }
>>> + /* If we are moving across superblocks drop the dcache entries */
>>> + if (old_tag != tag) {
>>> + struct super_block *sb;
>>> + struct dentry *dentry;
>>> + list_for_each_entry(sb, &sysfs_fs_type.fs_supers,
>>> s_instances) {
>>> + dentry = __sysfs_get_dentry(sb, sd);
>>> + if (!dentry)
>>> + continue;
>>> + shrink_dcache_parent(dentry);
>>> + d_drop(dentry);
>>> + dput(dentry);
>>> + }
>>> + }
>>> +
>>> error = 0;
>>> out_unlock:
>>> mutex_unlock(&sysfs_mutex);
>>> @@ -978,11 +1047,13 @@ int sysfs_move_dir(struct kobject *kobj, struct
>>> kobject *new_parent_kobj)
>>> struct sysfs_rename_struct *srs;
>>> struct inode *old_parent_inode = NULL, *new_parent_inode = NULL;
>>> int error;
>>> + const void *tag;
>>> INIT_LIST_HEAD(&todo);
>>> mutex_lock(&sysfs_rename_mutex);
>>> BUG_ON(!sd->s_parent);
>>> new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd :
>>> &sysfs_root;
>>> + tag = sd->s_tag;
>>> error = 0;
>>> if (sd->s_parent == new_parent_sd)
>>> @@ -1016,7 +1087,7 @@ again:
>>> mutex_lock(&sysfs_mutex);
>>> error = -EEXIST;
>>> - if (sysfs_find_dirent(new_parent_sd, sd->s_name))
>>> + if (sysfs_find_dirent(new_parent_sd, tag, sd->s_name))
>>> goto out_unlock;
>>> error = 0;
>>> @@ -1055,10 +1126,12 @@ static inline unsigned char dt_type(struct
>>> sysfs_dirent *sd)
>>> static int sysfs_readdir(struct file * filp, void * dirent, filldir_t
>>> filldir)
>>> {
>>> - struct dentry *dentry = filp->f_path.dentry;
>>> - struct sysfs_dirent * parent_sd = dentry->d_fsdata;
>>> + struct dentry *parent = filp->f_path.dentry;
>>> + struct sysfs_dirent *parent_sd = parent->d_fsdata;
>>> struct sysfs_dirent *pos;
>>> ino_t ino;
>>> + enum sysfs_tag_type type;
>>> + const void *tag;
>>> if (filp->f_pos == 0) {
>>> ino = parent_sd->s_ino;
>>> @@ -1076,6 +1149,9 @@ static int sysfs_readdir(struct file * filp, void *
>>> dirent, filldir_t filldir)
>>> if ((filp->f_pos > 1) && (filp->f_pos < INT_MAX)) {
>>> mutex_lock(&sysfs_mutex);
>>> + type = sysfs_tag_type(parent_sd);
>>> + tag = sysfs_info(parent->d_sb)->tag[type];
>>> +
>>> /* Skip the dentries we have already reported */
>>> pos = parent_sd->s_dir.children;
>>> while (pos && (filp->f_pos > pos->s_ino))
>>> @@ -1085,6 +1161,9 @@ static int sysfs_readdir(struct file * filp, void *
>>> dirent, filldir_t filldir)
>>> const char * name;
>>> int len;
>>> + if (pos->s_tag != tag)
>>> + continue;
>>> +
>>> name = pos->s_name;
>>> len = strlen(name);
>>> filp->f_pos = ino = pos->s_ino;
>>> @@ -1105,3 +1184,35 @@ const struct file_operations sysfs_dir_operations =
>>> {
>>> .read = generic_read_dir,
>>> .readdir = sysfs_readdir,
>>> };
>>> +
>>> +/**
>>> + * sysfs_make_tagged_dir - Require tags of all the entries in a
>>> directory.
>>> + * @kobj: object whose children should be filtered by tags
>>> + *
>>> + * Once tagging has been enabled on a directory the contents
>>> + * of the directory become dependent upon context captured when
>>> + * sysfs was mounted.
>>> + */
>>> +int sysfs_make_tagged_dir(struct kobject *kobj, enum sysfs_tag_type type)
>>> +{
>>> + struct sysfs_dirent *sd;
>>> + int err;
>>> +
>>> + err = -ENOENT;
>>> + sd = kobj->sd;
>>> +
>>> + mutex_lock(&sysfs_mutex);
>>> + err = -EINVAL;
>>> + /* We can only enable tagging when we have a valid tag type
>>> + * on empty directories where taggint has not already been
>>> + * enabled.
>>> + */
>>> + if ((type > SYSFS_TAG_TYPE_NONE) && (type < SYSFS_TAG_TYPES) &&
>>> + tag_ops[type] && !sysfs_tag_type(sd) &&
>>> + (sysfs_type(sd) == SYSFS_DIR) && !sd->s_dir.children) {
>>> + err = 0;
>>> + sd->s_flags |= (type << SYSFS_TAG_TYPE_SHIFT);
>>> + }
>>> + mutex_unlock(&sysfs_mutex);
>>> + return err;
>>> +}
>>> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
>>> index 61c3476..091c0de 100644
>>> --- a/fs/sysfs/file.c
>>> +++ b/fs/sysfs/file.c
>>> @@ -476,9 +476,12 @@ void sysfs_notify(struct kobject *k, char *dir, char
>>> *attr)
>>> mutex_lock(&sysfs_mutex);
>>> if (sd && dir)
>>> - sd = sysfs_find_dirent(sd, dir);
>>> + /* Only directories are tagged, so no need to pass
>>> + * a tag explicitly.
>>> + */
>>> + sd = sysfs_find_dirent(sd, NULL, dir);
>>> if (sd && attr)
>>> - sd = sysfs_find_dirent(sd, attr);
>>> + sd = sysfs_find_dirent(sd, NULL, attr);
>>> if (sd)
>>> sysfs_notify_dirent(sd);
>>> @@ -640,7 +643,7 @@ EXPORT_SYMBOL_GPL(sysfs_chmod_file);
>>> void sysfs_remove_file(struct kobject * kobj, const struct attribute *
>>> attr)
>>> {
>>> - sysfs_hash_and_remove(kobj->sd, attr->name);
>>> + sysfs_hash_and_remove(kobj, kobj->sd, attr->name);
>>> }
>>> @@ -660,7 +663,7 @@ void sysfs_remove_file_from_group(struct kobject
>>> *kobj,
>>> else
>>> dir_sd = sysfs_get(kobj->sd);
>>> if (dir_sd) {
>>> - sysfs_hash_and_remove(dir_sd, attr->name);
>>> + sysfs_hash_and_remove(kobj, dir_sd, attr->name);
>>> sysfs_put(dir_sd);
>>> }
>>> }
>>> diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
>>> index fe61194..5fba6f2 100644
>>> --- a/fs/sysfs/group.c
>>> +++ b/fs/sysfs/group.c
>>> @@ -23,7 +23,7 @@ static void remove_files(struct sysfs_dirent *dir_sd,
>>> struct kobject *kobj,
>>> int i;
>>> for (i = 0, attr = grp->attrs; *attr; i++, attr++)
>>> - sysfs_hash_and_remove(dir_sd, (*attr)->name);
>>> + sysfs_hash_and_remove(kobj, dir_sd, (*attr)->name);
>>> }
>>> static int create_files(struct sysfs_dirent *dir_sd, struct kobject
>>> *kobj,
>>> @@ -39,7 +39,7 @@ static int create_files(struct sysfs_dirent *dir_sd,
>>> struct kobject *kobj,
>>> * visibility. Do this by first removing then
>>> * re-adding (if required) the file */
>>> if (update)
>>> - sysfs_hash_and_remove(dir_sd, (*attr)->name);
>>> + sysfs_hash_and_remove(kobj, dir_sd,
>>> (*attr)->name);
>>> if (grp->is_visible) {
>>> mode = grp->is_visible(kobj, *attr, i);
>>> if (!mode)
>>> diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
>>> index 80f8fd4..b5fc78a 100644
>>> --- a/fs/sysfs/inode.c
>>> +++ b/fs/sysfs/inode.c
>>> @@ -226,17 +226,20 @@ struct inode * sysfs_get_inode(struct sysfs_dirent
>>> *sd)
>>> return inode;
>>> }
>>> -int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
>>> +int sysfs_hash_and_remove(struct kobject *kobj, struct sysfs_dirent
>>> *dir_sd,
>>> + const char *name)
>>> {
>>> struct sysfs_addrm_cxt acxt;
>>> struct sysfs_dirent *sd;
>>> + const void *tag;
>>> if (!dir_sd)
>>> return -ENOENT;
>>> sysfs_addrm_start(&acxt, dir_sd);
>>> + tag = kobj->sd->s_tag;
>>> - sd = sysfs_find_dirent(dir_sd, name);
>>> + sd = sysfs_find_dirent(dir_sd, tag, name);
>>> if (sd)
>>> sysfs_remove_one(&acxt, sd);
>>> diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
>>> index 6ebda1a..8f2237a 100644
>>> --- a/fs/sysfs/mount.c
>>> +++ b/fs/sysfs/mount.c
>>> @@ -35,12 +35,15 @@ static const struct super_operations sysfs_ops = {
>>> struct sysfs_dirent sysfs_root = {
>>> .s_name = "",
>>> .s_count = ATOMIC_INIT(1),
>>> - .s_flags = SYSFS_DIR,
>>> + .s_flags = SYSFS_DIR | (SYSFS_TAG_TYPE_NONE <<
>>> SYSFS_TAG_TYPE_SHIFT),
>>> .s_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
>>> .s_ino = 1,
>>> };
>>> -static int sysfs_fill_super(struct super_block *sb, void *data, int
>>> silent)
>>> +struct sysfs_tag_type_operations *tag_ops[SYSFS_TAG_TYPES];
>>> +
>>> +static int sysfs_fill_super(struct super_block *sb, void *data, int
>>> silent,
>>> + const void *tags[SYSFS_TAG_TYPES])
>>> {
>>> struct sysfs_super_info *info = NULL;
>>> struct inode *inode = NULL;
>>> @@ -76,8 +79,10 @@ static int sysfs_fill_super(struct super_block *sb,
>>> void *data, int silent)
>>> goto out_err;
>>> }
>>> root->d_fsdata = &sysfs_root;
>>> + root->d_sb = sb;
>>> sb->s_root = root;
>>> sb->s_fs_info = info;
>>> + memcpy(info->tag, tags, sizeof(info->tag[0])*SYSFS_TAG_TYPES);
>>> return 0;
>>> out_err:
>>> @@ -89,20 +94,74 @@ out_err:
>>> return error;
>>> }
>>> +static int sysfs_test_super(struct super_block *sb, void *ptr)
>>> +{
>>> + const void **tag = ptr;
>>> + struct sysfs_super_info *info = sysfs_info(sb);
>>> + enum sysfs_tag_type type;
>>> + int found = 1;
>>> +
>>> + for (type = SYSFS_TAG_TYPE_NONE; type < SYSFS_TAG_TYPES; type++) {
>>> + if (info->tag[type] != tag[type]) {
>>> + found = 0;
>>> + break;
>>> + }
>>> + }
>>> +
>>> + return found;
>>> +}
>>> +
>>> static int sysfs_get_sb(struct file_system_type *fs_type,
>>> int flags, const char *dev_name, void *data, struct vfsmount *mnt)
>>> {
>>> - int rc;
>>> + const void *tag[SYSFS_TAG_TYPES];
>>> + struct super_block *sb;
>>> + int error;
>>> + enum sysfs_tag_type type;
>>> +
>>> + for (type = SYSFS_TAG_TYPE_NONE; type < SYSFS_TAG_TYPES; type++) {
>>> + tag[type] = NULL;
>>> + if (!tag_ops[type])
>>> + continue;
>>> + tag[type] = tag_ops[type]->mount_tag();
>>> + }
>>> +
>>> mutex_lock(&sysfs_rename_mutex);
>>> - rc = get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
>>> + sb = sget(fs_type, sysfs_test_super, set_anon_super, tag);
>>> + if (IS_ERR(sb)) {
>>> + error = PTR_ERR(sb);
>>> + goto out;
>>> + }
>>> + if (!sb->s_root) {
>>> + sb->s_flags = flags;
>>> + error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 :
>>> 0,
>>> + tag);
>>> + if (error) {
>>> + up_write(&sb->s_umount);
>>> + deactivate_super(sb);
>>> + goto out;
>>> + }
>>> + sb->s_flags |= MS_ACTIVE;
>>> + }
>>> + do_remount_sb(sb, flags, data, 0);
>>> + error = simple_set_mnt(mnt, sb);
>>> +out:
>>> mutex_unlock(&sysfs_rename_mutex);
>>> - return rc;
>>> + return error;
>>> +}
>>> +
>>> +static void sysfs_kill_sb(struct super_block *sb)
>>> +{
>>> + struct sysfs_super_info *info = sysfs_info(sb);
>>> +
>>> + kill_anon_super(sb);
>>> + kfree(info);
>>> }
>>> struct file_system_type sysfs_fs_type = {
>>> .name = "sysfs",
>>> .get_sb = sysfs_get_sb,
>>> - .kill_sb = kill_anon_super,
>>> + .kill_sb = sysfs_kill_sb,
>>> };
>>> void sysfs_grab_supers(void)
>>> @@ -146,6 +205,50 @@ restart:
>>> spin_unlock(&sb_lock);
>>> }
>>> +int sysfs_register_tag_type(enum sysfs_tag_type type, struct
>>> sysfs_tag_type_operations *ops)
>>> +{
>>> + int error;
>>> +
>>> + mutex_lock(&sysfs_rename_mutex);
>>> +
>>> + error = -EINVAL;
>>> + if (type >= SYSFS_TAG_TYPES)
>>> + goto out;
>>> +
>>> + error = -EINVAL;
>>> + if (type <= SYSFS_TAG_TYPE_NONE)
>>> + goto out;
>>> +
>>> + error = -EBUSY;
>>> + if (tag_ops[type])
>>> + goto out;
>>> +
>>> + error = 0;
>>> + tag_ops[type] = ops;
>>> +
>>> +out:
>>> + mutex_unlock(&sysfs_rename_mutex);
>>> + return error;
>>> +}
>>> +
>>> +void sysfs_exit_tag(enum sysfs_tag_type type, const void *tag)
>>> +{
>>> + /* Allow the tag to go away while sysfs is still mounted. */
>>> + struct super_block *sb;
>>> + mutex_lock(&sysfs_rename_mutex);
>>> + sysfs_grab_supers();
>>> + mutex_lock(&sysfs_mutex);
>>> + list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) {
>>> + struct sysfs_super_info *info = sysfs_info(sb);
>>> + if (info->tag[type] != tag)
>>> + continue;
>>> + info->tag[type] = NULL;
>>> + }
>>> + mutex_unlock(&sysfs_mutex);
>>> + sysfs_release_supers();
>>> + mutex_unlock(&sysfs_rename_mutex);
>>> +}
>>> +
>>> int __init sysfs_init(void)
>>> {
>>> int err = -ENOMEM;
>>> diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
>>> index a3ba217..54b2e5f 100644
>>> --- a/fs/sysfs/symlink.c
>>> +++ b/fs/sysfs/symlink.c
>>> @@ -119,7 +119,7 @@ void sysfs_remove_link(struct kobject * kobj, const
>>> char * name)
>>> else
>>> parent_sd = kobj->sd;
>>> - sysfs_hash_and_remove(parent_sd, name);
>>> + sysfs_hash_and_remove(kobj, parent_sd, name);
>>> }
>>> static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
>>> diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
>>> index f0e5ecb..67115ec 100644
>>> --- a/fs/sysfs/sysfs.h
>>> +++ b/fs/sysfs/sysfs.h
>>> @@ -45,6 +45,7 @@ struct sysfs_dirent {
>>> struct sysfs_dirent *s_sibling;
>>> const char *s_name;
>>> + const void *s_tag;
>>> union {
>>> struct sysfs_elem_dir s_dir;
>>> struct sysfs_elem_symlink s_symlink;
>>> @@ -67,14 +68,22 @@ struct sysfs_dirent {
>>> #define SYSFS_KOBJ_LINK 0x0008
>>> #define SYSFS_COPY_NAME (SYSFS_DIR |
>>> SYSFS_KOBJ_LINK)
>>> -#define SYSFS_FLAG_MASK ~SYSFS_TYPE_MASK
>>> -#define SYSFS_FLAG_REMOVED 0x0200
>>> +#define SYSFS_TAG_TYPE_MASK 0xff00
>>> +#define SYSFS_TAG_TYPE_SHIFT 8
>>> +
>>> +#define SYSFS_FLAG_MASK ~(SYSFS_TYPE_MASK |
>>> SYSFS_TAG_TYPE_MASK)
>>> +#define SYSFS_FLAG_REMOVED 0x020000
>>> static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
>>> {
>>> return sd->s_flags & SYSFS_TYPE_MASK;
>>> }
>>> +static inline enum sysfs_tag_type sysfs_tag_type(struct sysfs_dirent
>>> *sd)
>>> +{
>>> + return (sd->s_flags & SYSFS_TAG_TYPE_MASK) >>
>>> SYSFS_TAG_TYPE_SHIFT;
>>> +}
>>> +
>>> /*
>>> * Context structure to be used while adding/removing nodes.
>>> */
>>> @@ -87,6 +96,7 @@ struct sysfs_addrm_cxt {
>>> struct sysfs_super_info {
>>> int grabbed;
>>> + const void *tag[SYSFS_TAG_TYPES];
>>> };
>>> #define sysfs_info(SB) ((struct sysfs_super_info *)(SB)->s_fs_info)
>>> @@ -98,6 +108,7 @@ extern struct sysfs_dirent sysfs_root;
>>> extern struct super_block *sysfs_sb;
>>> extern struct kmem_cache *sysfs_dir_cachep;
>>> extern struct file_system_type sysfs_fs_type;
>>> +extern struct sysfs_tag_type_operations *tag_ops[SYSFS_TAG_TYPES];
>>> void sysfs_grab_supers(void);
>>> void sysfs_release_supers(void);
>>> @@ -124,6 +135,7 @@ void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
>>> struct sysfs_dirent *sd);
>>> void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
>>> struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
>>> + const void *tag,
>>> const unsigned char *name);
>>> struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
>>> const unsigned char *name);
>>> @@ -158,7 +170,8 @@ static inline void __sysfs_put(struct sysfs_dirent
>>> *sd)
>>> struct inode *sysfs_get_inode(struct sysfs_dirent *sd);
>>> int sysfs_sd_setattr(struct sysfs_dirent *sd, struct inode *inode, struct
>>> iattr *iattr);
>>> int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
>>> -int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name);
>>> +int sysfs_hash_and_remove(struct kobject *kobj, struct sysfs_dirent
>>> *dir_sd,
>>> + const char *name);
>>> int sysfs_inode_init(void);
>>> /*
>>> diff --git a/include/linux/kobject.h b/include/linux/kobject.h
>>> index 5437ac0..beb3573 100644
>>> --- a/include/linux/kobject.h
>>> +++ b/include/linux/kobject.h
>>> @@ -105,6 +105,7 @@ struct kobj_type {
>>> void (*release)(struct kobject *kobj);
>>> struct sysfs_ops *sysfs_ops;
>>> struct attribute **default_attrs;
>>> + const void *(*sysfs_tag)(struct kobject *kobj);
>>> };
>>> struct kobj_uevent_env {
>>> diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
>>> index d8e0230..ba68829 100644
>>> --- a/include/linux/sysfs.h
>>> +++ b/include/linux/sysfs.h
>>> @@ -80,6 +80,15 @@ struct sysfs_ops {
>>> struct sysfs_dirent;
>>> +enum sysfs_tag_type {
>>> + SYSFS_TAG_TYPE_NONE = 0,
>>> + SYSFS_TAG_TYPES
>>> +};
>>> +
>>> +struct sysfs_tag_type_operations {
>>> + const void *(*mount_tag)(void);
>>> +};
>>> +
>>> #ifdef CONFIG_SYSFS
>>> int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
>>> @@ -126,6 +135,12 @@ struct sysfs_dirent *sysfs_get_dirent(struct
>>> sysfs_dirent *parent_sd,
>>> struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd);
>>> void sysfs_put(struct sysfs_dirent *sd);
>>> void sysfs_printk_last_file(void);
>>> +
>>> +int sysfs_make_tagged_dir(struct kobject *, enum sysfs_tag_type
>>> tag_type);
>>> +int sysfs_register_tag_type(enum sysfs_tag_type type,
>>> + struct sysfs_tag_type_operations *ops);
>>> +void sysfs_exit_tag(enum sysfs_tag_type type, const void *tag);
>>> +
>>> int __must_check sysfs_init(void);
>>> #else /* CONFIG_SYSFS */
>>> @@ -249,6 +264,22 @@ static inline void sysfs_put(struct sysfs_dirent *sd)
>>> {
>>> }
>>> +staticn inline int sysfs_make_tagged_dir(struct kobject *kobj,
>> ______^
>>
>> This typo is still present in your patch in the CONFIG_SYSFS=n case.
>>
>> Otherwise the patchset, combined with the patches Greg has already
>> merged in his tree, still works great for me with network namespaces.
>>
>> --Benjamin
>>
>>> + enum sysfs_tag_type
>>> tag_type)
>>> +{
>>> + return 0;
>>> +}
>>> +
>>> +static inline int sysfs_register_tag_type(enum sysfs_tag_type type,
>>> + struct sysfs_tag_type_operations
>>> *ops)
>>> +{
>>> + return 0;
>>> +}
>>> +
>>> +static inline void sysfs_exit_tag(enum sysfs_tag_type type, const void
>>> *tag)
>>> +{
>>> +}
>>> +
>>> static inline int __must_check sysfs_init(void)
>>> {
>>> return 0;
>>
>> --
>> B e n j a m i n T h e r y - BULL/DT/Open Software R&D
>>
>>
http://www.bull.com
>> --
>> To unsubscribe from this list: send the line "unsubscribe netdev" in
>> the body of a message to
majordomo@vger.kernel.org
>> More majordomo info at
http://vger.kernel.org/majordomo-info.html
>>
>
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