sysfs: add sysfs_dirent->s_name

Add s_name to sysfs_dirent.  This is to further reduce dependency to
the associated dentry.  Name is copied for directories and symlinks
but not for attributes.

Where possible, name dereferences are converted to use sd->s_name.
sysfs_symlink->link_name and sysfs_get_name() are unused now and
removed.

This change allows symlink to be implemented using sysfs_dirent tree
proper, which is the last remaining dentry-dependent sysfs walk.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 44 insertions, 23 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 5d50e1ddfbd1..6e8d6f54f082 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -54,10 +54,11 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
 
         if (sd->s_type & SYSFS_KOBJ_LINK) {
                 struct sysfs_symlink * sl = sd->s_element;
-                kfree(sl->link_name);
                 kobject_put(sl->target_kobj);
                 kfree(sl);
         }
+        if (sd->s_type & SYSFS_COPY_NAME)
+                kfree(sd->s_name);
         kfree(sd->s_iattr);
         sysfs_free_ino(sd->s_ino);
         kmem_cache_free(sysfs_dir_cachep, sd);
@@ -94,29 +95,41 @@ static struct dentry_operations sysfs_dentry_ops = {
         .d_iput         = sysfs_d_iput,
 };
 
-struct sysfs_dirent *sysfs_new_dirent(void *element, umode_t mode, int type)
+struct sysfs_dirent *sysfs_new_dirent(const char *name, void *element,
+                                      umode_t mode, int type)
 {
-        struct sysfs_dirent * sd;
+        char *dup_name = NULL;
+        struct sysfs_dirent *sd = NULL;
+
+        if (type & SYSFS_COPY_NAME) {
+                name = dup_name = kstrdup(name, GFP_KERNEL);
+                if (!name)
+                        goto err_out;
+        }
 
         sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
         if (!sd)
-                return NULL;
+                goto err_out;
 
-        if (sysfs_alloc_ino(&sd->s_ino)) {
-                kmem_cache_free(sysfs_dir_cachep, sd);
-                return NULL;
-        }
+        if (sysfs_alloc_ino(&sd->s_ino))
+                goto err_out;
 
         atomic_set(&sd->s_count, 1);
         atomic_set(&sd->s_event, 1);
         INIT_LIST_HEAD(&sd->s_children);
         INIT_LIST_HEAD(&sd->s_sibling);
 
+        sd->s_name = name;
         sd->s_element = element;
         sd->s_mode = mode;
         sd->s_type = type;
 
         return sd;
+
+ err_out:
+        kfree(dup_name);
+        kmem_cache_free(sysfs_dir_cachep, sd);
+        return NULL;
 }
 
 void sysfs_attach_dirent(struct sysfs_dirent *sd,
@@ -148,8 +161,7 @@ int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
 
         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
                 if (sd->s_element) {
-                        const unsigned char *existing = sysfs_get_name(sd);
-                        if (strcmp(existing, new))
+                        if (strcmp(sd->s_name, new))
                                 continue;
                         else
                                 return -EEXIST;
@@ -203,7 +215,7 @@ static int create_dir(struct kobject *kobj, struct dentry *parent,
                 goto out_dput;
 
         error = -ENOMEM;
-        sd = sysfs_new_dirent(kobj, mode, SYSFS_DIR);
+        sd = sysfs_new_dirent(name, kobj, mode, SYSFS_DIR);
         if (!sd)
                 goto out_drop;
         sysfs_attach_dirent(sd, parent->d_fsdata, dentry);
@@ -334,9 +346,7 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 
         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
                 if (sd->s_type & SYSFS_NOT_PINNED) {
-                        const unsigned char * name = sysfs_get_name(sd);
-
-                        if (strcmp(name, dentry->d_name.name))
+                        if (strcmp(sd->s_name, dentry->d_name.name))
                                 continue;
 
                         if (sd->s_type & SYSFS_KOBJ_LINK)
@@ -427,9 +437,11 @@ void sysfs_remove_dir(struct kobject * kobj)
 int sysfs_rename_dir(struct kobject * kobj, struct dentry *new_parent,
                      const char *new_name)
 {
+        struct sysfs_dirent *sd = kobj->dentry->d_fsdata;
+        struct sysfs_dirent *parent_sd = new_parent->d_fsdata;
+        struct dentry *new_dentry;
+        char *dup_name;
         int error;
-        struct dentry * new_dentry;
-        struct sysfs_dirent *sd, *parent_sd;
 
         if (!new_parent)
                 return -EFAULT;
@@ -457,22 +469,31 @@ int sysfs_rename_dir(struct kobject * kobj, struct dentry *new_parent,
         if (new_dentry->d_inode)
                 goto out_dput;
 
+        /* rename kobject and sysfs_dirent */
+        error = -ENOMEM;
+        new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
+        if (!new_name)
+                goto out_drop;
+
         error = kobject_set_name(kobj, "%s", new_name);
         if (error)
-                goto out_drop;
+                goto out_free;
 
+        kfree(sd->s_name);
+        sd->s_name = new_name;
+
+        /* move under the new parent */
         d_add(new_dentry, NULL);
         d_move(kobj->dentry, new_dentry);
 
-        sd = kobj->dentry->d_fsdata;
-        parent_sd = new_parent->d_fsdata;
-
         list_del_init(&sd->s_sibling);
         list_add(&sd->s_sibling, &parent_sd->s_children);
 
         error = 0;
         goto out_unlock;
 
+ out_free:
+        kfree(dup_name);
  out_drop:
         d_drop(new_dentry);
  out_dput:
@@ -535,7 +556,7 @@ static int sysfs_dir_open(struct inode *inode, struct file *file)
         struct sysfs_dirent * sd;
 
         mutex_lock(&dentry->d_inode->i_mutex);
-        sd = sysfs_new_dirent(NULL, 0, 0);
+        sd = sysfs_new_dirent("_DIR_", NULL, 0, 0);
         if (sd)
                 sysfs_attach_dirent(sd, parent_sd, NULL);
         mutex_unlock(&dentry->d_inode->i_mutex);
@@ -605,7 +626,7 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
                                 if (!next->s_element)
                                         continue;
 
-                                name = sysfs_get_name(next);
+                                name = next->s_name;
                                 len = strlen(name);
                                 ino = next->s_ino;
 
@@ -717,7 +738,7 @@ struct dentry *sysfs_create_shadow_dir(struct kobject *kobj)
         if (!shadow)
                 goto nomem;
 
-        sd = sysfs_new_dirent(kobj, inode->i_mode, SYSFS_DIR);
+        sd = sysfs_new_dirent("_SHADOW_", kobj, inode->i_mode, SYSFS_DIR);
         if (!sd)
                 goto nomem;
         /* point to parent_sd but don't attach to it */