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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167// SPDX-License-Identifier: GPL-2.0-only/* Copyright (c) 2026 Christian Brauner <brauner@kernel.org> */#include <linux/fs.h>#include <linux/fs/super_types.h>#include <linux/fs_context.h>#include <linux/fs_struct.h>#include <linux/magic.h>#include <linux/mount.h>
#include "internal.h"
static struct path failfs_root_path = {};
void failfs_get_root(struct path *path){ *path = failfs_root_path; path_get(path);}
bool failfs_mnt(const struct vfsmount *mnt){ return mnt->mnt_sb == failfs_root_path.mnt->mnt_sb;}
static int failfs_permission(const struct mnt_idmap *idmap, struct inode *inode, int mask){ return -EOPNOTSUPP;}
static struct dentry *failfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags){ /* Unreachable: ->permission() already failed the walk. */ return ERR_PTR(-EOPNOTSUPP);}
static int failfs_getattr(const struct mnt_idmap *idmap, const struct path *path, struct kstat *stat, u32 request_mask, unsigned int query_flags){ return -EOPNOTSUPP;}
static const struct inode_operations failfs_dir_inode_operations = { .permission = failfs_permission, .lookup = failfs_lookup, .getattr = failfs_getattr,};
static const struct file_operations failfs_dir_operations = {};
static int failfs_d_weak_revalidate(struct dentry *dentry, unsigned int flags){ /* * The root is only ever reached as a path-walk terminal by jumping * to it: as "/" when it is the caller's root, or through a * /proc/<pid>/{root,cwd} magic link. ->permission() already fails * every walk of a component, but a jump lands on the root without * one. Refuse here too so the root cannot be pinned by an O_PATH * open or encoded into a file handle. */ return -EOPNOTSUPP;}
static char *failfs_dname(struct dentry *dentry, char *buffer, int buflen){ return dynamic_dname(buffer, buflen, "failfs:/");}
static const struct dentry_operations failfs_dentry_operations = { .d_dname = failfs_dname, .d_weak_revalidate = failfs_d_weak_revalidate,};
static int failfs_statfs(struct dentry *dentry, struct kstatfs *buf){ return -EOPNOTSUPP;}
static const struct super_operations failfs_super_operations = { .statfs = failfs_statfs,};
static int failfs_fill_super(struct super_block *s, struct fs_context *fc){ struct inode *inode;
s->s_maxbytes = MAX_LFS_FILESIZE; s->s_blocksize = PAGE_SIZE; s->s_blocksize_bits = PAGE_SHIFT; s->s_magic = FAIL_FS_MAGIC; s->s_op = &failfs_super_operations; s->s_export_op = NULL; s->s_xattr = NULL; s->s_time_gran = 1; s->s_d_flags = 0;
inode = new_inode(s); if (!inode) return -ENOMEM;
/* failfs supports no operations... */ inode->i_mode = S_IFDIR; set_nlink(inode, 2); inode->i_op = &failfs_dir_inode_operations; inode->i_fop = &failfs_dir_operations; simple_inode_init_ts(inode); inode->i_ino = 1; /* ... and is immutable. */ inode->i_flags |= S_IMMUTABLE;
set_default_d_op(s, &failfs_dentry_operations); s->s_root = d_make_root(inode); if (!s->s_root) return -ENOMEM;
return 0;}
static int failfs_get_tree(struct fs_context *fc){ return get_tree_single(fc, failfs_fill_super);}
static const struct fs_context_operations failfs_context_ops = { .get_tree = failfs_get_tree,};
static int failfs_init_fs_context(struct fs_context *fc){ fc->ops = &failfs_context_ops; fc->global = true; fc->sb_flags |= SB_NOUSER; fc->s_iflags |= SB_I_NOEXEC | SB_I_NODEV; return 0;}
int failfs_current_chdir(void){ struct path path;
failfs_get_root(&path); set_fs_pwd(current->fs, &path); path_put(&path); return 0;}
static struct file_system_type failfs_fs_type = { .name = "failfs", .init_fs_context = failfs_init_fs_context, .kill_sb = kill_anon_super,};
void __init failfs_init(void){ struct vfsmount *mnt;
/* A single instance that is member of no mount namespace. */ mnt = kern_mount(&failfs_fs_type); if (IS_ERR(mnt)) panic("VFS: Failed to create failfs");
failfs_root_path.mnt = mnt; failfs_root_path.dentry = mnt->mnt_root;}