diff options
| -rw-r--r-- | fs/kernfs/mount.c | 56 | ||||
| -rw-r--r-- | include/linux/kernfs.h | 12 | ||||
| -rw-r--r-- | kernel/cgroup/cgroup.c | 3 |
3 files changed, 70 insertions, 1 deletions
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index acd542625fd8..fa323589704f 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -16,6 +16,7 @@ #include <linux/pagemap.h> #include <linux/namei.h> #include <linux/seq_file.h> +#include <linux/exportfs.h> #include "kernfs-internal.h" @@ -64,6 +65,59 @@ const struct super_operations kernfs_sops = { .show_path = kernfs_sop_show_path, }; +static struct inode *kernfs_fh_get_inode(struct super_block *sb, + u64 ino, u32 generation) +{ + struct kernfs_super_info *info = kernfs_info(sb); + struct inode *inode; + struct kernfs_node *kn; + + if (ino == 0) + return ERR_PTR(-ESTALE); + + kn = kernfs_find_and_get_node_by_ino(info->root, ino); + if (!kn) + return ERR_PTR(-ESTALE); + inode = kernfs_get_inode(sb, kn); + kernfs_put(kn); + if (IS_ERR(inode)) + return ERR_CAST(inode); + + if (generation && inode->i_generation != generation) { + /* we didn't find the right inode.. */ + iput(inode); + return ERR_PTR(-ESTALE); + } + return inode; +} + +static struct dentry *kernfs_fh_to_dentry(struct super_block *sb, struct fid *fid, + int fh_len, int fh_type) +{ + return generic_fh_to_dentry(sb, fid, fh_len, fh_type, + kernfs_fh_get_inode); +} + +static struct dentry *kernfs_fh_to_parent(struct super_block *sb, struct fid *fid, + int fh_len, int fh_type) +{ + return generic_fh_to_parent(sb, fid, fh_len, fh_type, + kernfs_fh_get_inode); +} + +static struct dentry *kernfs_get_parent_dentry(struct dentry *child) +{ + struct kernfs_node *kn = kernfs_dentry_node(child); + + return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent)); +} + +static const struct export_operations kernfs_export_ops = { + .fh_to_dentry = kernfs_fh_to_dentry, + .fh_to_parent = kernfs_fh_to_parent, + .get_parent = kernfs_get_parent_dentry, +}; + /** * kernfs_root_from_sb - determine kernfs_root associated with a super_block * @sb: the super_block in question @@ -159,6 +213,8 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic) sb->s_magic = magic; sb->s_op = &kernfs_sops; sb->s_xattr = kernfs_xattr_handlers; + if (info->root->flags & KERNFS_ROOT_SUPPORT_EXPORTOP) + sb->s_export_op = &kernfs_export_ops; sb->s_time_gran = 1; /* get root inode, initialize and unlock it */ diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 06a0c5913e1d..d149361e5875 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -69,6 +69,12 @@ enum kernfs_root_flag { * following flag enables that behavior. */ KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK = 0x0002, + + /* + * The filesystem supports exportfs operation, so userspace can use + * fhandle to access nodes of the fs. + */ + KERNFS_ROOT_SUPPORT_EXPORTOP = 0x0004, }; /* type-specific structures for kernfs_node union members */ @@ -98,6 +104,12 @@ struct kernfs_elem_attr { /* represent a kernfs node */ union kernfs_node_id { struct { + /* + * blktrace will export this struct as a simplified 'struct + * fid' (which is a big data struction), so userspace can use + * it to find kernfs node. The layout must match the first two + * fields of 'struct fid' exactly. + */ u32 ino; u32 generation; }; diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 620794a20a33..6cefa277f39c 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -1737,7 +1737,8 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask, int ref_flags) &cgroup_kf_syscall_ops : &cgroup1_kf_syscall_ops; root->kf_root = kernfs_create_root(kf_sops, - KERNFS_ROOT_CREATE_DEACTIVATED, + KERNFS_ROOT_CREATE_DEACTIVATED | + KERNFS_ROOT_SUPPORT_EXPORTOP, root_cgrp); if (IS_ERR(root->kf_root)) { ret = PTR_ERR(root->kf_root); |