sysfs: Remove first pass at shadow directory support

While shadow directories appear to be a good idea, the current scheme
of controlling their creation and destruction outside of sysfs appears
to be a locking and maintenance nightmare in the face of sysfs
directories dynamically coming and going.  Which can now occur for
directories containing network devices when CONFIG_SYSFS_DEPRECATED is
not set.

This patch removes everything from the initial shadow directory support
that allowed the shadow directory creation to be controlled at a higher
level.  So except for a few bits of sysfs_rename_dir everything from
commit b592fcfe7f06c15ec11774b5be7ce0de3aa86e73 is now gone.

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

5 files changed, 23 insertions, 163 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 86d75e08de60..837073dbadf4 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -569,9 +569,6 @@ static void sysfs_drop_dentry(struct sysfs_dirent *sd)
         spin_unlock(&dcache_lock);
         spin_unlock(&sysfs_assoc_lock);
 
-        /* dentries for shadowed inodes are pinned, unpin */
-        if (dentry && sysfs_is_shadowed_inode(dentry->d_inode))
-                dput(dentry);
         dput(dentry);
 
         /* adjust nlink and update timestamp */
@@ -723,19 +720,15 @@ int sysfs_create_subdir(struct kobject *kobj, const char *name,
 /**
  *      sysfs_create_dir - create a directory for an object.
  *      @kobj:          object we're creating directory for. 
- *      @shadow_parent: parent object.
  */
-int sysfs_create_dir(struct kobject *kobj,
-                     struct sysfs_dirent *shadow_parent_sd)
+int sysfs_create_dir(struct kobject * kobj)
 {
         struct sysfs_dirent *parent_sd, *sd;
         int error = 0;
 
         BUG_ON(!kobj);
 
-        if (shadow_parent_sd)
-                parent_sd = shadow_parent_sd;
-        else if (kobj->parent)
+        if (kobj->parent)
                 parent_sd = kobj->parent->sd;
         else if (sysfs_mount && sysfs_mount->mnt_sb)
                 parent_sd = sysfs_mount->mnt_sb->s_root->d_fsdata;
@@ -890,45 +883,44 @@ void sysfs_remove_dir(struct kobject * kobj)
         __sysfs_remove_dir(sd);
 }
 
-int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
-                     const char *new_name)
+int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
 {
-        struct sysfs_dirent *sd = kobj->sd;
-        struct dentry *new_parent = NULL;
+        struct sysfs_dirent *sd;
+        struct dentry *parent = NULL;
         struct dentry *old_dentry = NULL, *new_dentry = NULL;
+        struct sysfs_dirent *parent_sd;
         const char *dup_name = NULL;
         int error;
 
+        if (!kobj->parent)
+                return -EINVAL;
+
         /* get dentries */
+        sd = kobj->sd;
         old_dentry = sysfs_get_dentry(sd);
         if (IS_ERR(old_dentry)) {
                 error = PTR_ERR(old_dentry);
                 goto out_dput;
         }
 
-        new_parent = sysfs_get_dentry(new_parent_sd);
-        if (IS_ERR(new_parent)) {
-                error = PTR_ERR(new_parent);
+        parent_sd = kobj->parent->sd;
+        parent = sysfs_get_dentry(parent_sd);
+        if (IS_ERR(parent)) {
+                error = PTR_ERR(parent);
                 goto out_dput;
         }
 
-        /* lock new_parent and get dentry for new name */
-        mutex_lock(&new_parent->d_inode->i_mutex);
+        /* lock parent and get dentry for new name */
+        mutex_lock(&parent->d_inode->i_mutex);
 
-        new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));
+        new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
         if (IS_ERR(new_dentry)) {
                 error = PTR_ERR(new_dentry);
                 goto out_unlock;
         }
 
-        /* By allowing two different directories with the same
-         * d_parent we allow this routine to move between different
-         * shadows of the same directory
-         */
         error = -EINVAL;
-        if (old_dentry->d_parent->d_inode != new_parent->d_inode ||
-            new_dentry->d_parent->d_inode != new_parent->d_inode ||
-            old_dentry == new_dentry)
+        if (old_dentry == new_dentry)
                 goto out_unlock;
 
         error = -EEXIST;
@@ -955,9 +947,9 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
         d_move(sd->s_dentry, new_dentry);
 
         sysfs_unlink_sibling(sd);
-        sysfs_get(new_parent_sd);
+        sysfs_get(parent_sd);
         sysfs_put(sd->s_parent);
-        sd->s_parent = new_parent_sd;
+        sd->s_parent = parent_sd;
         sysfs_link_sibling(sd);
 
         mutex_unlock(&sysfs_mutex);
@@ -968,10 +960,10 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
  out_drop:
         d_drop(new_dentry);
  out_unlock:
-        mutex_unlock(&new_parent->d_inode->i_mutex);
+        mutex_unlock(&parent->d_inode->i_mutex);
  out_dput:
         kfree(dup_name);
-        dput(new_parent);
+        dput(parent);
         dput(old_dentry);
         dput(new_dentry);
         return error;
@@ -1192,121 +1184,6 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
         return offset;
 }
 
-
-/**
- *      sysfs_make_shadowed_dir - Setup so a directory can be shadowed
- *      @kobj:  object we're creating shadow of.
- */
-
-int sysfs_make_shadowed_dir(struct kobject *kobj,
-        void * (*follow_link)(struct dentry *, struct nameidata *))
-{
-        struct dentry *dentry;
-        struct inode *inode;
-        struct inode_operations *i_op;
-
-        /* get dentry for @kobj->sd, dentry of a shadowed dir is pinned */
-        dentry = sysfs_get_dentry(kobj->sd);
-        if (IS_ERR(dentry))
-                return PTR_ERR(dentry);
-
-        inode = dentry->d_inode;
-        if (inode->i_op != &sysfs_dir_inode_operations) {
-                dput(dentry);
-                return -EINVAL;
-        }
-
-        i_op = kmalloc(sizeof(*i_op), GFP_KERNEL);
-        if (!i_op)
-                return -ENOMEM;
-
-        memcpy(i_op, &sysfs_dir_inode_operations, sizeof(*i_op));
-        i_op->follow_link = follow_link;
-
-        /* Locking of inode->i_op?
-         * Since setting i_op is a single word write and they
-         * are atomic we should be ok here.
-         */
-        inode->i_op = i_op;
-        return 0;
-}
-
-/**
- *      sysfs_create_shadow_dir - create a shadow directory for an object.
- *      @kobj:  object we're creating directory for.
- *
- *      sysfs_make_shadowed_dir must already have been called on this
- *      directory.
- */
-
-struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj)
-{
-        struct sysfs_dirent *parent_sd = kobj->sd->s_parent;
-        struct dentry *dir, *parent, *shadow;
-        struct inode *inode;
-        struct sysfs_dirent *sd;
-        struct sysfs_addrm_cxt acxt;
-
-        dir = sysfs_get_dentry(kobj->sd);
-        if (IS_ERR(dir)) {
-                sd = (void *)dir;
-                goto out;
-        }
-        parent = dir->d_parent;
-
-        inode = dir->d_inode;
-        sd = ERR_PTR(-EINVAL);
-        if (!sysfs_is_shadowed_inode(inode))
-                goto out_dput;
-
-        shadow = d_alloc(parent, &dir->d_name);
-        if (!shadow)
-                goto nomem;
-
-        sd = sysfs_new_dirent("_SHADOW_", inode->i_mode, SYSFS_DIR);
-        if (!sd)
-                goto nomem;
-        sd->s_elem.dir.kobj = kobj;
-
-        sysfs_addrm_start(&acxt, parent_sd);
-
-        /* add but don't link into children list */
-        sysfs_add_one(&acxt, sd);
-
-        /* attach and instantiate dentry */
-        sysfs_attach_dentry(sd, shadow);
-        d_instantiate(shadow, igrab(inode));
-        inc_nlink(inode);       /* tj: synchronization? */
-
-        sysfs_addrm_finish(&acxt);
-
-        dget(shadow);           /* Extra count - pin the dentry in core */
-
-        goto out_dput;
-
- nomem:
-        dput(shadow);
-        sd = ERR_PTR(-ENOMEM);
- out_dput:
-        dput(dir);
- out:
-        return sd;
-}
-
-/**
- *      sysfs_remove_shadow_dir - remove an object's directory.
- *      @shadow_sd: sysfs_dirent of shadow directory
- *
- *      The only thing special about this is that we remove any files in
- *      the directory before we remove the directory, and we've inlined
- *      what used to be sysfs_rmdir() below, instead of calling separately.
- */
-
-void sysfs_remove_shadow_dir(struct sysfs_dirent *shadow_sd)
-{
-        __sysfs_remove_dir(shadow_sd);
-}
-
 const struct file_operations sysfs_dir_operations = {
         .open           = sysfs_dir_open,
         .release        = sysfs_dir_close,
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index e6b904d71633..d1972374655a 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -13,7 +13,6 @@
 #include <linux/dcache.h>
 #include <linux/namei.h>
 #include <linux/err.h>
-#include <linux/fs.h>
 #include "sysfs.h"
 
 
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index aecb6e771e2a..45128b79bc68 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -33,16 +33,6 @@ static const struct inode_operations sysfs_inode_operations ={
         .setattr        = sysfs_setattr,
 };
 
-void sysfs_delete_inode(struct inode *inode)
-{
-        /* Free the shadowed directory inode operations */
-        if (sysfs_is_shadowed_inode(inode)) {
-                kfree(inode->i_op);
-                inode->i_op = NULL;
-        }
-        return generic_delete_inode(inode);
-}
-
 int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
 {
         struct inode * inode = dentry->d_inode;
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 69a73ae307fe..119f39da1ae1 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -20,7 +20,7 @@ struct kmem_cache *sysfs_dir_cachep;
 
 static const struct super_operations sysfs_ops = {
         .statfs         = simple_statfs,
-        .drop_inode     = sysfs_delete_inode,
+        .drop_inode     = generic_delete_inode,
 };
 
 struct sysfs_dirent sysfs_root = {
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 6b8c8d76d308..b55e510ea239 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -70,7 +70,6 @@ extern void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
                              struct sysfs_dirent *sd);
 extern int sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
 
-extern void sysfs_delete_inode(struct inode *inode);
 extern struct inode * sysfs_get_inode(struct sysfs_dirent *sd);
 extern void sysfs_instantiate(struct dentry *dentry, struct inode *inode);
 
@@ -121,8 +120,3 @@ static inline void sysfs_put(struct sysfs_dirent * sd)
         if (sd && atomic_dec_and_test(&sd->s_count))
                 release_sysfs_dirent(sd);
 }
-
-static inline int sysfs_is_shadowed_inode(struct inode *inode)
-{
-        return S_ISDIR(inode->i_mode) && inode->i_op->follow_link;
-}