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authorSang-Heon Jeon <ekffu200098@gmail.com>2026-08-24 01:18:14 +0900
committerJulia Lawall <Julia.Lawall@inria.fr>2026-08-23 22:12:11 +0200
commit2bd30b8dc75b823dd7bbef9d7bc68e1fd7ecee5c (patch)
treedcc4da1d99f17541c5590ac63c77da4bf372a4ab /fs/failfs.c
downloadlinux-stable-2bd30b8dc75b823dd7bbef9d7bc68e1fd7ecee5c.tar.gz
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coccinelle: alloc_cast: drop removed allocatorsgrafted
- pci_alloc_consistent() and pci_zalloc_consistent() were removed by commit 7968778914e5 ("PCI: Remove the deprecated "pci-dma-compat.h" API") - kmem_alloc() was removed by commit f078d4ea8276 ("xfs: convert kmem_alloc() to kmalloc()") - kmem_zalloc() was removed by commit 10634530f7ba ("xfs: convert kmem_zalloc() to kzalloc()") - kmem_zone_alloc() and kmem_zone_zalloc() were removed by commit bae633a4a283 ("xfs: remove xfs_zone_{alloc,zalloc} helpers") So drop them from the rules. No functional change. Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com> Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Diffstat (limited to 'fs/failfs.c')
-rw-r--r--fs/failfs.c166
1 files changed, 166 insertions, 0 deletions
diff --git a/fs/failfs.c b/fs/failfs.c
new file mode 100644
index 000000000..66a36da3d
--- /dev/null
+++ b/fs/failfs.c
@@ -0,0 +1,166 @@
+// 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(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(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;
+}