configfs: new object reprsenting tree fragments
commit 47320fbe11a6059ae502c9c16b668022fdb4cf76 upstream.
Refcounted, hangs of configfs_dirent, created by operations that add
fragments to configfs tree (mkdir and configfs_register_{subsystem,group}).
Will be used in the next commit to provide exclusion between fragment
removal and ->show/->store calls.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Al Viro
Greg Kroah-Hartman
parent
65524d647e
commit
25c118d8d1
3 changed files with 97 additions and 27 deletions
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@ -34,6 +34,15 @@
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#include <linux/list.h>
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#include <linux/spinlock.h>
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struct configfs_fragment {
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atomic_t frag_count;
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struct rw_semaphore frag_sem;
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bool frag_dead;
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};
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void put_fragment(struct configfs_fragment *);
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struct configfs_fragment *get_fragment(struct configfs_fragment *);
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struct configfs_dirent {
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atomic_t s_count;
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int s_dependent_count;
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@ -48,6 +57,7 @@ struct configfs_dirent {
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#ifdef CONFIG_LOCKDEP
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int s_depth;
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#endif
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struct configfs_fragment *s_frag;
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};
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#define CONFIGFS_ROOT 0x0001
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@ -75,8 +85,8 @@ extern int configfs_create(struct dentry *, umode_t mode, void (*init)(struct in
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extern int configfs_create_file(struct config_item *, const struct configfs_attribute *);
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extern int configfs_create_bin_file(struct config_item *,
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const struct configfs_bin_attribute *);
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extern int configfs_make_dirent(struct configfs_dirent *,
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struct dentry *, void *, umode_t, int);
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extern int configfs_make_dirent(struct configfs_dirent *, struct dentry *,
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void *, umode_t, int, struct configfs_fragment *);
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extern int configfs_dirent_is_ready(struct configfs_dirent *);
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extern void configfs_hash_and_remove(struct dentry * dir, const char * name);
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@ -151,6 +161,7 @@ static inline void release_configfs_dirent(struct configfs_dirent * sd)
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{
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if (!(sd->s_type & CONFIGFS_ROOT)) {
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kfree(sd->s_iattr);
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put_fragment(sd->s_frag);
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kmem_cache_free(configfs_dir_cachep, sd);
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}
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}
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@ -164,11 +164,38 @@ configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
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#endif /* CONFIG_LOCKDEP */
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static struct configfs_fragment *new_fragment(void)
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{
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struct configfs_fragment *p;
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p = kmalloc(sizeof(struct configfs_fragment), GFP_KERNEL);
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if (p) {
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atomic_set(&p->frag_count, 1);
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init_rwsem(&p->frag_sem);
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p->frag_dead = false;
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}
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return p;
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}
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void put_fragment(struct configfs_fragment *frag)
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{
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if (frag && atomic_dec_and_test(&frag->frag_count))
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kfree(frag);
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}
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struct configfs_fragment *get_fragment(struct configfs_fragment *frag)
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{
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if (likely(frag))
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atomic_inc(&frag->frag_count);
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return frag;
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}
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/*
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* Allocates a new configfs_dirent and links it to the parent configfs_dirent
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*/
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static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
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void *element, int type)
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void *element, int type,
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struct configfs_fragment *frag)
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{
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struct configfs_dirent * sd;
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@ -188,6 +215,7 @@ static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *paren
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kmem_cache_free(configfs_dir_cachep, sd);
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return ERR_PTR(-ENOENT);
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}
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sd->s_frag = get_fragment(frag);
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list_add(&sd->s_sibling, &parent_sd->s_children);
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spin_unlock(&configfs_dirent_lock);
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@ -222,11 +250,11 @@ static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
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int configfs_make_dirent(struct configfs_dirent * parent_sd,
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struct dentry * dentry, void * element,
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umode_t mode, int type)
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umode_t mode, int type, struct configfs_fragment *frag)
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{
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struct configfs_dirent * sd;
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sd = configfs_new_dirent(parent_sd, element, type);
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sd = configfs_new_dirent(parent_sd, element, type, frag);
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if (IS_ERR(sd))
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return PTR_ERR(sd);
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@ -273,7 +301,8 @@ static void init_symlink(struct inode * inode)
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* until it is validated by configfs_dir_set_ready()
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*/
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static int configfs_create_dir(struct config_item *item, struct dentry *dentry)
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static int configfs_create_dir(struct config_item *item, struct dentry *dentry,
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struct configfs_fragment *frag)
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{
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int error;
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umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
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@ -286,7 +315,8 @@ static int configfs_create_dir(struct config_item *item, struct dentry *dentry)
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return error;
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error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,
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CONFIGFS_DIR | CONFIGFS_USET_CREATING);
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CONFIGFS_DIR | CONFIGFS_USET_CREATING,
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frag);
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if (unlikely(error))
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return error;
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@ -351,9 +381,10 @@ int configfs_create_link(struct configfs_symlink *sl,
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{
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int err = 0;
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umode_t mode = S_IFLNK | S_IRWXUGO;
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struct configfs_dirent *p = parent->d_fsdata;
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err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
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CONFIGFS_ITEM_LINK);
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err = configfs_make_dirent(p, dentry, sl, mode,
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CONFIGFS_ITEM_LINK, p->s_frag);
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if (!err) {
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err = configfs_create(dentry, mode, init_symlink);
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if (err) {
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@ -612,7 +643,8 @@ static int populate_attrs(struct config_item *item)
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static int configfs_attach_group(struct config_item *parent_item,
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struct config_item *item,
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struct dentry *dentry);
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struct dentry *dentry,
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struct configfs_fragment *frag);
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static void configfs_detach_group(struct config_item *item);
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static void detach_groups(struct config_group *group)
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@ -660,7 +692,8 @@ static void detach_groups(struct config_group *group)
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* try using vfs_mkdir. Just a thought.
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*/
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static int create_default_group(struct config_group *parent_group,
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struct config_group *group)
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struct config_group *group,
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struct configfs_fragment *frag)
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{
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int ret;
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struct configfs_dirent *sd;
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@ -676,7 +709,7 @@ static int create_default_group(struct config_group *parent_group,
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d_add(child, NULL);
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ret = configfs_attach_group(&parent_group->cg_item,
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&group->cg_item, child);
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&group->cg_item, child, frag);
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if (!ret) {
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sd = child->d_fsdata;
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sd->s_type |= CONFIGFS_USET_DEFAULT;
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@ -690,13 +723,14 @@ static int create_default_group(struct config_group *parent_group,
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return ret;
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}
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static int populate_groups(struct config_group *group)
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static int populate_groups(struct config_group *group,
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struct configfs_fragment *frag)
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{
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struct config_group *new_group;
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int ret = 0;
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list_for_each_entry(new_group, &group->default_groups, group_entry) {
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ret = create_default_group(group, new_group);
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ret = create_default_group(group, new_group, frag);
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if (ret) {
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detach_groups(group);
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break;
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@ -810,11 +844,12 @@ static void link_group(struct config_group *parent_group, struct config_group *g
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*/
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static int configfs_attach_item(struct config_item *parent_item,
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struct config_item *item,
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struct dentry *dentry)
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struct dentry *dentry,
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struct configfs_fragment *frag)
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{
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int ret;
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ret = configfs_create_dir(item, dentry);
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ret = configfs_create_dir(item, dentry, frag);
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if (!ret) {
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ret = populate_attrs(item);
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if (ret) {
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@ -844,12 +879,13 @@ static void configfs_detach_item(struct config_item *item)
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static int configfs_attach_group(struct config_item *parent_item,
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struct config_item *item,
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struct dentry *dentry)
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struct dentry *dentry,
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struct configfs_fragment *frag)
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{
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int ret;
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struct configfs_dirent *sd;
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ret = configfs_attach_item(parent_item, item, dentry);
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ret = configfs_attach_item(parent_item, item, dentry, frag);
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if (!ret) {
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sd = dentry->d_fsdata;
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sd->s_type |= CONFIGFS_USET_DIR;
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@ -865,7 +901,7 @@ static int configfs_attach_group(struct config_item *parent_item,
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*/
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inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
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configfs_adjust_dir_dirent_depth_before_populate(sd);
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ret = populate_groups(to_config_group(item));
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ret = populate_groups(to_config_group(item), frag);
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if (ret) {
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configfs_detach_item(item);
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d_inode(dentry)->i_flags |= S_DEAD;
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@ -1260,6 +1296,7 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
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struct configfs_dirent *sd;
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const struct config_item_type *type;
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struct module *subsys_owner = NULL, *new_item_owner = NULL;
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struct configfs_fragment *frag;
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char *name;
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sd = dentry->d_parent->d_fsdata;
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@ -1278,6 +1315,12 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
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goto out;
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}
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frag = new_fragment();
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if (!frag) {
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ret = -ENOMEM;
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goto out;
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}
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/* Get a working ref for the duration of this function */
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parent_item = configfs_get_config_item(dentry->d_parent);
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type = parent_item->ci_type;
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@ -1380,9 +1423,9 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
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spin_unlock(&configfs_dirent_lock);
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if (group)
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ret = configfs_attach_group(parent_item, item, dentry);
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ret = configfs_attach_group(parent_item, item, dentry, frag);
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else
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ret = configfs_attach_item(parent_item, item, dentry);
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ret = configfs_attach_item(parent_item, item, dentry, frag);
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spin_lock(&configfs_dirent_lock);
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sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
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@ -1419,6 +1462,7 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
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* reference.
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*/
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config_item_put(parent_item);
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put_fragment(frag);
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out:
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return ret;
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@ -1587,7 +1631,7 @@ static int configfs_dir_open(struct inode *inode, struct file *file)
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*/
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err = -ENOENT;
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if (configfs_dirent_is_ready(parent_sd)) {
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file->private_data = configfs_new_dirent(parent_sd, NULL, 0);
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file->private_data = configfs_new_dirent(parent_sd, NULL, 0, NULL);
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if (IS_ERR(file->private_data))
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err = PTR_ERR(file->private_data);
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else
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@ -1743,8 +1787,13 @@ int configfs_register_group(struct config_group *parent_group,
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{
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struct configfs_subsystem *subsys = parent_group->cg_subsys;
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struct dentry *parent;
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struct configfs_fragment *frag;
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int ret;
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frag = new_fragment();
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if (!frag)
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return -ENOMEM;
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mutex_lock(&subsys->su_mutex);
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link_group(parent_group, group);
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mutex_unlock(&subsys->su_mutex);
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@ -1752,7 +1801,7 @@ int configfs_register_group(struct config_group *parent_group,
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parent = parent_group->cg_item.ci_dentry;
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inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
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ret = create_default_group(parent_group, group);
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ret = create_default_group(parent_group, group, frag);
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if (ret)
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goto err_out;
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@ -1760,12 +1809,14 @@ int configfs_register_group(struct config_group *parent_group,
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configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
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spin_unlock(&configfs_dirent_lock);
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inode_unlock(d_inode(parent));
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put_fragment(frag);
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return 0;
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err_out:
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inode_unlock(d_inode(parent));
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mutex_lock(&subsys->su_mutex);
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unlink_group(group);
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mutex_unlock(&subsys->su_mutex);
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put_fragment(frag);
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return ret;
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}
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EXPORT_SYMBOL(configfs_register_group);
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@ -1852,10 +1903,17 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
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struct dentry *dentry;
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struct dentry *root;
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struct configfs_dirent *sd;
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struct configfs_fragment *frag;
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frag = new_fragment();
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if (!frag)
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return -ENOMEM;
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root = configfs_pin_fs();
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if (IS_ERR(root))
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if (IS_ERR(root)) {
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put_fragment(frag);
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return PTR_ERR(root);
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}
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if (!group->cg_item.ci_name)
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group->cg_item.ci_name = group->cg_item.ci_namebuf;
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@ -1871,7 +1929,7 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
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d_add(dentry, NULL);
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err = configfs_attach_group(sd->s_element, &group->cg_item,
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dentry);
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dentry, frag);
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if (err) {
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BUG_ON(d_inode(dentry));
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d_drop(dentry);
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@ -1889,6 +1947,7 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
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unlink_group(group);
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configfs_release_fs();
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}
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put_fragment(frag);
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return err;
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}
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@ -502,7 +502,7 @@ int configfs_create_file(struct config_item * item, const struct configfs_attrib
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inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL);
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error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
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CONFIGFS_ITEM_ATTR);
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CONFIGFS_ITEM_ATTR, parent_sd->s_frag);
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inode_unlock(d_inode(dir));
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return error;
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@ -524,7 +524,7 @@ int configfs_create_bin_file(struct config_item *item,
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inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL);
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error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,
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CONFIGFS_ITEM_BIN_ATTR);
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CONFIGFS_ITEM_BIN_ATTR, parent_sd->s_frag);
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inode_unlock(dir->d_inode);
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return error;
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