172 lines
4.2 KiB
C
172 lines
4.2 KiB
C
/*
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* fs/kernfs/mount.c - kernfs mount implementation
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*
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* Copyright (c) 2001-3 Patrick Mochel
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
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*
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* This file is released under the GPLv2.
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*/
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/init.h>
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#include <linux/magic.h>
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#include <linux/slab.h>
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#include <linux/pagemap.h>
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#include "kernfs-internal.h"
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struct kmem_cache *kernfs_node_cache;
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static const struct super_operations kernfs_sops = {
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.statfs = simple_statfs,
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.drop_inode = generic_delete_inode,
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.evict_inode = kernfs_evict_inode,
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};
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static int kernfs_fill_super(struct super_block *sb)
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{
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struct kernfs_super_info *info = kernfs_info(sb);
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struct inode *inode;
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struct dentry *root;
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sb->s_blocksize = PAGE_CACHE_SIZE;
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sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
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sb->s_magic = SYSFS_MAGIC;
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sb->s_op = &kernfs_sops;
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sb->s_time_gran = 1;
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/* get root inode, initialize and unlock it */
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mutex_lock(&kernfs_mutex);
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inode = kernfs_get_inode(sb, info->root->kn);
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mutex_unlock(&kernfs_mutex);
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if (!inode) {
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pr_debug("kernfs: could not get root inode\n");
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return -ENOMEM;
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}
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/* instantiate and link root dentry */
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root = d_make_root(inode);
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if (!root) {
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pr_debug("%s: could not get root dentry!\n", __func__);
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return -ENOMEM;
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}
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kernfs_get(info->root->kn);
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root->d_fsdata = info->root->kn;
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sb->s_root = root;
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sb->s_d_op = &kernfs_dops;
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return 0;
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}
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static int kernfs_test_super(struct super_block *sb, void *data)
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{
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struct kernfs_super_info *sb_info = kernfs_info(sb);
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struct kernfs_super_info *info = data;
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return sb_info->root == info->root && sb_info->ns == info->ns;
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}
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static int kernfs_set_super(struct super_block *sb, void *data)
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{
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int error;
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error = set_anon_super(sb, data);
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if (!error)
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sb->s_fs_info = data;
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return error;
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}
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/**
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* kernfs_super_ns - determine the namespace tag of a kernfs super_block
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* @sb: super_block of interest
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*
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* Return the namespace tag associated with kernfs super_block @sb.
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*/
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const void *kernfs_super_ns(struct super_block *sb)
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{
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struct kernfs_super_info *info = kernfs_info(sb);
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return info->ns;
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}
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/**
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* kernfs_mount_ns - kernfs mount helper
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* @fs_type: file_system_type of the fs being mounted
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* @flags: mount flags specified for the mount
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* @root: kernfs_root of the hierarchy being mounted
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* @new_sb_created: tell the caller if we allocated a new superblock
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* @ns: optional namespace tag of the mount
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*
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* This is to be called from each kernfs user's file_system_type->mount()
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* implementation, which should pass through the specified @fs_type and
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* @flags, and specify the hierarchy and namespace tag to mount via @root
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* and @ns, respectively.
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*
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* The return value can be passed to the vfs layer verbatim.
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*/
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struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
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struct kernfs_root *root, bool *new_sb_created,
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const void *ns)
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{
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struct super_block *sb;
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struct kernfs_super_info *info;
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int error;
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info = kzalloc(sizeof(*info), GFP_KERNEL);
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if (!info)
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return ERR_PTR(-ENOMEM);
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info->root = root;
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info->ns = ns;
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sb = sget(fs_type, kernfs_test_super, kernfs_set_super, flags, info);
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if (IS_ERR(sb) || sb->s_fs_info != info)
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kfree(info);
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if (IS_ERR(sb))
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return ERR_CAST(sb);
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if (new_sb_created)
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*new_sb_created = !sb->s_root;
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if (!sb->s_root) {
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error = kernfs_fill_super(sb);
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if (error) {
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deactivate_locked_super(sb);
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return ERR_PTR(error);
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}
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sb->s_flags |= MS_ACTIVE;
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}
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return dget(sb->s_root);
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}
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/**
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* kernfs_kill_sb - kill_sb for kernfs
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* @sb: super_block being killed
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*
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* This can be used directly for file_system_type->kill_sb(). If a kernfs
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* user needs extra cleanup, it can implement its own kill_sb() and call
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* this function at the end.
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*/
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void kernfs_kill_sb(struct super_block *sb)
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{
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struct kernfs_super_info *info = kernfs_info(sb);
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struct kernfs_node *root_kn = sb->s_root->d_fsdata;
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/*
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* Remove the superblock from fs_supers/s_instances
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* so we can't find it, before freeing kernfs_super_info.
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*/
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kill_anon_super(sb);
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kfree(info);
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kernfs_put(root_kn);
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}
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void __init kernfs_init(void)
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{
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kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
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sizeof(struct kernfs_node),
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0, SLAB_PANIC, NULL);
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kernfs_inode_init();
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}
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