diff options
Diffstat (limited to 'fs/kernfs/mount.c')
| -rw-r--r-- | fs/kernfs/mount.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c new file mode 100644 index 000000000000..6a5f04ac8704 --- /dev/null +++ b/fs/kernfs/mount.c @@ -0,0 +1,208 @@ +/* + * fs/kernfs/mount.c - kernfs mount implementation + * + * Copyright (c) 2001-3 Patrick Mochel + * Copyright (c) 2007 SUSE Linux Products GmbH + * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> + * + * This file is released under the GPLv2. + */ + +#include <linux/fs.h> +#include <linux/mount.h> +#include <linux/init.h> +#include <linux/magic.h> +#include <linux/slab.h> +#include <linux/pagemap.h> + +#include "kernfs-internal.h" + +struct kmem_cache *kernfs_node_cache; + +static int kernfs_sop_remount_fs(struct super_block *sb, int *flags, char *data) +{ + struct kernfs_root *root = kernfs_info(sb)->root; + struct kernfs_syscall_ops *scops = root->syscall_ops; + + if (scops && scops->remount_fs) + return scops->remount_fs(root, flags, data); + return 0; +} + +static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry) +{ + struct kernfs_root *root = kernfs_root(dentry->d_fsdata); + struct kernfs_syscall_ops *scops = root->syscall_ops; + + if (scops && scops->show_options) + return scops->show_options(sf, root); + return 0; +} + +const struct super_operations kernfs_sops = { + .statfs = simple_statfs, + .drop_inode = generic_delete_inode, + .evict_inode = kernfs_evict_inode, + + .remount_fs = kernfs_sop_remount_fs, + .show_options = kernfs_sop_show_options, +}; + +/** + * kernfs_root_from_sb - determine kernfs_root associated with a super_block + * @sb: the super_block in question + * + * Return the kernfs_root associated with @sb. If @sb is not a kernfs one, + * %NULL is returned. + */ +struct kernfs_root *kernfs_root_from_sb(struct super_block *sb) +{ + if (sb->s_op == &kernfs_sops) + return kernfs_info(sb)->root; + return NULL; +} + +static int kernfs_fill_super(struct super_block *sb) +{ + struct kernfs_super_info *info = kernfs_info(sb); + struct inode *inode; + struct dentry *root; + + sb->s_blocksize = PAGE_CACHE_SIZE; + sb->s_blocksize_bits = PAGE_CACHE_SHIFT; + sb->s_magic = SYSFS_MAGIC; + sb->s_op = &kernfs_sops; + sb->s_time_gran = 1; + + /* get root inode, initialize and unlock it */ + mutex_lock(&kernfs_mutex); + inode = kernfs_get_inode(sb, info->root->kn); + mutex_unlock(&kernfs_mutex); + if (!inode) { + pr_debug("kernfs: could not get root inode\n"); + return -ENOMEM; + } + + /* instantiate and link root dentry */ + root = d_make_root(inode); + if (!root) { + pr_debug("%s: could not get root dentry!\n", __func__); + return -ENOMEM; + } + kernfs_get(info->root->kn); + root->d_fsdata = info->root->kn; + sb->s_root = root; + sb->s_d_op = &kernfs_dops; + return 0; +} + +static int kernfs_test_super(struct super_block *sb, void *data) +{ + struct kernfs_super_info *sb_info = kernfs_info(sb); + struct kernfs_super_info *info = data; + + return sb_info->root == info->root && sb_info->ns == info->ns; +} + +static int kernfs_set_super(struct super_block *sb, void *data) +{ + int error; + error = set_anon_super(sb, data); + if (!error) + sb->s_fs_info = data; + return error; +} + +/** + * kernfs_super_ns - determine the namespace tag of a kernfs super_block + * @sb: super_block of interest + * + * Return the namespace tag associated with kernfs super_block @sb. + */ +const void *kernfs_super_ns(struct super_block *sb) +{ + struct kernfs_super_info *info = kernfs_info(sb); + + return info->ns; +} + +/** + * kernfs_mount_ns - kernfs mount helper + * @fs_type: file_system_type of the fs being mounted + * @flags: mount flags specified for the mount + * @root: kernfs_root of the hierarchy being mounted + * @new_sb_created: tell the caller if we allocated a new superblock + * @ns: optional namespace tag of the mount + * + * This is to be called from each kernfs user's file_system_type->mount() + * implementation, which should pass through the specified @fs_type and + * @flags, and specify the hierarchy and namespace tag to mount via @root + * and @ns, respectively. + * + * The return value can be passed to the vfs layer verbatim. + */ +struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags, + struct kernfs_root *root, bool *new_sb_created, + const void *ns) +{ + struct super_block *sb; + struct kernfs_super_info *info; + int error; + + info = kzalloc(sizeof(*info), GFP_KERNEL); + if (!info) + return ERR_PTR(-ENOMEM); + + info->root = root; + info->ns = ns; + + sb = sget(fs_type, kernfs_test_super, kernfs_set_super, flags, info); + if (IS_ERR(sb) || sb->s_fs_info != info) + kfree(info); + if (IS_ERR(sb)) + return ERR_CAST(sb); + + if (new_sb_created) + *new_sb_created = !sb->s_root; + + if (!sb->s_root) { + error = kernfs_fill_super(sb); + if (error) { + deactivate_locked_super(sb); + return ERR_PTR(error); + } + sb->s_flags |= MS_ACTIVE; + } + + return dget(sb->s_root); +} + +/** + * kernfs_kill_sb - kill_sb for kernfs + * @sb: super_block being killed + * + * This can be used directly for file_system_type->kill_sb(). If a kernfs + * user needs extra cleanup, it can implement its own kill_sb() and call + * this function at the end. + */ +void kernfs_kill_sb(struct super_block *sb) +{ + struct kernfs_super_info *info = kernfs_info(sb); + struct kernfs_node *root_kn = sb->s_root->d_fsdata; + + /* + * Remove the superblock from fs_supers/s_instances + * so we can't find it, before freeing kernfs_super_info. + */ + kill_anon_super(sb); + kfree(info); + kernfs_put(root_kn); +} + +void __init kernfs_init(void) +{ + kernfs_node_cache = kmem_cache_create("kernfs_node_cache", + sizeof(struct kernfs_node), + 0, SLAB_PANIC, NULL); + kernfs_inode_init(); +} |
