anon_inodes: move allocation of anon_inode into ->mount()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 56 insertions, 53 deletions

diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index f11e43ed907d..28d39fb84ae3 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -39,19 +39,6 @@ static const struct dentry_operations anon_inodefs_dentry_operations = {
         .d_dname        = anon_inodefs_dname,
 };
 
-static struct dentry *anon_inodefs_mount(struct file_system_type *fs_type,
-                                int flags, const char *dev_name, void *data)
-{
-        return mount_pseudo(fs_type, "anon_inode:", NULL,
-                        &anon_inodefs_dentry_operations, ANON_INODE_FS_MAGIC);
-}
-
-static struct file_system_type anon_inode_fs_type = {
-        .name           = "anon_inodefs",
-        .mount          = anon_inodefs_mount,
-        .kill_sb        = kill_anon_super,
-};
-
 /*
  * nop .set_page_dirty method so that people can use .page_mkwrite on
  * anon inodes.
@@ -65,6 +52,62 @@ static const struct address_space_operations anon_aops = {
         .set_page_dirty = anon_set_page_dirty,
 };
 
+/*
+ * A single inode exists for all anon_inode files. Contrary to pipes,
+ * anon_inode inodes have no associated per-instance data, so we need
+ * only allocate one of them.
+ */
+static struct inode *anon_inode_mkinode(struct super_block *s)
+{
+        struct inode *inode = new_inode_pseudo(s);
+
+        if (!inode)
+                return ERR_PTR(-ENOMEM);
+
+        inode->i_ino = get_next_ino();
+        inode->i_fop = &anon_inode_fops;
+
+        inode->i_mapping->a_ops = &anon_aops;
+
+        /*
+         * Mark the inode dirty from the very beginning,
+         * that way it will never be moved to the dirty
+         * list because mark_inode_dirty() will think
+         * that it already _is_ on the dirty list.
+         */
+        inode->i_state = I_DIRTY;
+        inode->i_mode = S_IRUSR | S_IWUSR;
+        inode->i_uid = current_fsuid();
+        inode->i_gid = current_fsgid();
+        inode->i_flags |= S_PRIVATE;
+        inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+        return inode;
+}
+
+static struct dentry *anon_inodefs_mount(struct file_system_type *fs_type,
+                                int flags, const char *dev_name, void *data)
+{
+        struct dentry *root;
+        root = mount_pseudo(fs_type, "anon_inode:", NULL,
+                        &anon_inodefs_dentry_operations, ANON_INODE_FS_MAGIC);
+        if (!IS_ERR(root)) {
+                struct super_block *s = root->d_sb;
+                anon_inode_inode = anon_inode_mkinode(s);
+                if (IS_ERR(anon_inode_inode)) {
+                        dput(root);
+                        deactivate_locked_super(s);
+                        root = ERR_CAST(anon_inode_inode);
+                }
+        }
+        return root;
+}
+
+static struct file_system_type anon_inode_fs_type = {
+        .name           = "anon_inodefs",
+        .mount          = anon_inodefs_mount,
+        .kill_sb        = kill_anon_super,
+};
+
 /**
  * anon_inode_getfile - creates a new file instance by hooking it up to an
  *                      anonymous inode, and a dentry that describe the "class"
@@ -180,38 +223,6 @@ err_put_unused_fd:
 }
 EXPORT_SYMBOL_GPL(anon_inode_getfd);
 
-/*
- * A single inode exists for all anon_inode files. Contrary to pipes,
- * anon_inode inodes have no associated per-instance data, so we need
- * only allocate one of them.
- */
-static struct inode *anon_inode_mkinode(void)
-{
-        struct inode *inode = new_inode_pseudo(anon_inode_mnt->mnt_sb);
-
-        if (!inode)
-                return ERR_PTR(-ENOMEM);
-
-        inode->i_ino = get_next_ino();
-        inode->i_fop = &anon_inode_fops;
-
-        inode->i_mapping->a_ops = &anon_aops;
-
-        /*
-         * Mark the inode dirty from the very beginning,
-         * that way it will never be moved to the dirty
-         * list because mark_inode_dirty() will think
-         * that it already _is_ on the dirty list.
-         */
-        inode->i_state = I_DIRTY;
-        inode->i_mode = S_IRUSR | S_IWUSR;
-        inode->i_uid = current_fsuid();
-        inode->i_gid = current_fsgid();
-        inode->i_flags |= S_PRIVATE;
-        inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
-        return inode;
-}
-
 static int __init anon_inode_init(void)
 {
         int error;
@@ -224,16 +235,8 @@ static int __init anon_inode_init(void)
                 error = PTR_ERR(anon_inode_mnt);
                 goto err_unregister_filesystem;
         }
-        anon_inode_inode = anon_inode_mkinode();
-        if (IS_ERR(anon_inode_inode)) {
-                error = PTR_ERR(anon_inode_inode);
-                goto err_mntput;
-        }
-
         return 0;
 
-err_mntput:
-        kern_unmount(anon_inode_mnt);
 err_unregister_filesystem:
         unregister_filesystem(&anon_inode_fs_type);
 err_exit: