This is the basic inode and filesystem implementation.
Signed-off-by: Alexander Larsson <alexl@xxxxxxxxxx>
Co-developed-by: Giuseppe Scrivano <gscrivan@xxxxxxxxxx>
Signed-off-by: Giuseppe Scrivano <gscrivan@xxxxxxxxxx>
---
fs/composefs/cfs.c | 903 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 903 insertions(+)
create mode 100644 fs/composefs/cfs.c
diff --git a/fs/composefs/cfs.c b/fs/composefs/cfs.c
new file mode 100644
index 000000000000..b3c0adb69983
--- /dev/null
+++ b/fs/composefs/cfs.c
@@ -0,0 +1,903 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * composefs
+ *
+ * Copyright (C) 2000 Linus Torvalds.
+ * 2000 Transmeta Corp.
+ * Copyright (C) 2021 Giuseppe Scrivano
+ * Copyright (C) 2022 Alexander Larsson
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/exportfs.h>
+#include <linux/fsverity.h>
+#include <linux/fs_parser.h>
+#include <linux/module.h>
+#include <linux/namei.h>
+#include <linux/seq_file.h>
+#include <linux/version.h>
+#include <linux/xattr.h>
+#include <linux/statfs.h>
+
+#include "cfs-internals.h"
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Giuseppe Scrivano <gscrivan@xxxxxxxxxx>");
+
+#define CFS_MAX_STACK 500
+
+#define FILEID_CFS 0x91
+
+struct cfs_info {
+ struct cfs_context_s cfs_ctx;
+
+ char *base_path;
+
+ size_t n_bases;
+ struct vfsmount **bases;
+
+ u32 verity_check; /* 0 == none, 1 == if specified in image, 2 == require in image */
+ bool has_digest;
+ u8 digest[SHA256_DIGEST_SIZE]; /* fs-verity digest */
+};
+
+struct cfs_inode {
+ /* must be first for clear in cfs_alloc_inode to work */
+ struct inode vfs_inode;
+
+ struct cfs_inode_data_s inode_data;
+};
+
+static inline struct cfs_inode *CFS_I(struct inode *inode)
+{
+ return container_of(inode, struct cfs_inode, vfs_inode);
+}
+
+static struct file empty_file;
+
+static const struct file_operations cfs_file_operations;
+
+static const struct super_operations cfs_ops;
+static const struct file_operations cfs_dir_operations;
+static const struct inode_operations cfs_dir_inode_operations;
+static const struct inode_operations cfs_file_inode_operations;
+static const struct inode_operations cfs_link_inode_operations;
+
+static const struct xattr_handler *cfs_xattr_handlers[];
+static const struct export_operations cfs_export_operations;
+
+static const struct address_space_operations cfs_aops = {
+ .direct_IO = noop_direct_IO,
+};
+
+static ssize_t cfs_listxattr(struct dentry *dentry, char *names, size_t size);
+
+/* copied from overlayfs. */
+static unsigned int cfs_split_basedirs(char *str)
+{
+ unsigned int ctr = 1;
+ char *s, *d;
+
+ for (s = d = str;; s++, d++) {
+ if (*s == '\\') {
+ s++;
+ } else if (*s == ':') {
+ *d = '\0';
+ ctr++;
+ continue;
+ }
+ *d = *s;
+ if (!*s)
+ break;
+ }
+ return ctr;
+}
+
+static struct inode *cfs_make_inode(struct cfs_context_s *ctx,
+ struct super_block *sb, ino_t ino_num,
+ struct cfs_inode_s *ino, const struct inode *dir)
+{
+ struct cfs_inode_data_s inode_data = { 0 };
+ struct cfs_xattr_header_s *xattrs = NULL;
+ struct inode *inode = NULL;
+ struct cfs_inode *cino;
+ int ret, res;
+
+ res = cfs_init_inode_data(ctx, ino, ino_num, &inode_data);
+ if (res < 0)
+ return ERR_PTR(res);
+
+ inode = new_inode(sb);
+ if (inode) {
+ inode_init_owner(&init_user_ns, inode, dir, ino->st_mode);
+ inode->i_mapping->a_ops = &cfs_aops;
+
+ cino = CFS_I(inode);
+ cino->inode_data = inode_data;
+
+ inode->i_ino = ino_num;
+ set_nlink(inode, ino->st_nlink);
+ inode->i_rdev = ino->st_rdev;
+ inode->i_uid = make_kuid(current_user_ns(), ino->st_uid);
+ inode->i_gid = make_kgid(current_user_ns(), ino->st_gid);
+ inode->i_mode = ino->st_mode;
+ inode->i_atime = ino->st_mtim;
+ inode->i_mtime = ino->st_mtim;
+ inode->i_ctime = ino->st_ctim;
+
+ switch (ino->st_mode & S_IFMT) {
+ case S_IFREG:
+ inode->i_op = &cfs_file_inode_operations;
+ inode->i_fop = &cfs_file_operations;
+ inode->i_size = ino->st_size;
+ break;
+ case S_IFLNK:
+ inode->i_link = cino->inode_data.path_payload;
+ inode->i_op = &cfs_link_inode_operations;
+ inode->i_fop = &cfs_file_operations;
+ break;
+ case S_IFDIR:
+ inode->i_op = &cfs_dir_inode_operations;
+ inode->i_fop = &cfs_dir_operations;
+ inode->i_size = 4096;
+ break;
+ case S_IFCHR:
+ case S_IFBLK:
+ if (current_user_ns() != &init_user_ns) {
+ ret = -EPERM;
+ goto fail;
+ }
+ fallthrough;
+ default:
+ inode->i_op = &cfs_file_inode_operations;
+ init_special_inode(inode, ino->st_mode, ino->st_rdev);
+ break;
+ }
+ }
+ return inode;
+
+fail:
+ if (inode)
+ iput(inode);
+ kfree(xattrs);
+ cfs_inode_data_put(&inode_data);
+ return ERR_PTR(ret);
+}
+
+static struct inode *cfs_get_root_inode(struct super_block *sb)
+{
+ struct cfs_info *fsi = sb->s_fs_info;
+ struct cfs_inode_s ino_buf;
+ struct cfs_inode_s *ino;
+ u64 index;
+
+ ino = cfs_get_root_ino(&fsi->cfs_ctx, &ino_buf, &index);
+ if (IS_ERR(ino))
+ return ERR_CAST(ino);
+
+ return cfs_make_inode(&fsi->cfs_ctx, sb, index, ino, NULL);
+}
+
+static bool cfs_iterate_cb(void *private, const char *name, int name_len,
+ u64 ino, unsigned int dtype)
+{
+ struct dir_context *ctx = private;
+
+ if (!dir_emit(ctx, name, name_len, ino, dtype))
+ return 0;
+
+ ctx->pos++;
+ return 1;
+}
+
+static int cfs_iterate(struct file *file, struct dir_context *ctx)
+{
+ struct inode *inode = file->f_inode;
+ struct cfs_info *fsi = inode->i_sb->s_fs_info;
+ struct cfs_inode *cino = CFS_I(inode);
+
+ if (!dir_emit_dots(file, ctx))
+ return 0;
+
+ return cfs_dir_iterate(&fsi->cfs_ctx, inode->i_ino, &cino->inode_data,
+ ctx->pos - 2, cfs_iterate_cb, ctx);
+}
+
+static struct dentry *cfs_lookup(struct inode *dir, struct dentry *dentry,
+ unsigned int flags)
+{
+ struct cfs_info *fsi = dir->i_sb->s_fs_info;
+ struct cfs_inode *cino = CFS_I(dir);
+ struct cfs_inode_s ino_buf;
+ struct cfs_inode_s *ino_s;
+ struct inode *inode;
+ u64 index;
+ int ret;
+
+ if (dentry->d_name.len > NAME_MAX)
+ return ERR_PTR(-ENAMETOOLONG);
+
+ ret = cfs_dir_lookup(&fsi->cfs_ctx, dir->i_ino, &cino->inode_data,
+ dentry->d_name.name, dentry->d_name.len, &index);
+ if (ret < 0)
+ return ERR_PTR(ret);
+ if (ret == 0)
+ goto return_negative;
+
+ ino_s = cfs_get_ino_index(&fsi->cfs_ctx, index, &ino_buf);
+ if (IS_ERR(ino_s))
+ return ERR_CAST(ino_s);
+
+ inode = cfs_make_inode(&fsi->cfs_ctx, dir->i_sb, index, ino_s, dir);
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
+
+ return d_splice_alias(inode, dentry);
+
+return_negative:
+ d_add(dentry, NULL);
+ return NULL;
+}
+
+static const struct file_operations cfs_dir_operations = {
+ .llseek = generic_file_llseek,
+ .read = generic_read_dir,
+ .iterate_shared = cfs_iterate,
+};
+
+static const struct inode_operations cfs_dir_inode_operations = {
+ .lookup = cfs_lookup,
+ .listxattr = cfs_listxattr,
+};
+
+static const struct inode_operations cfs_link_inode_operations = {
+ .get_link = simple_get_link,
+ .listxattr = cfs_listxattr,
+};
+
+static int digest_from_string(const char *digest_str, u8 *digest)
+{
+ int res;
+
+ res = hex2bin(digest, digest_str, SHA256_DIGEST_SIZE);
+ if (res < 0)
+ return res;
+
+ if (digest_str[2 * SHA256_DIGEST_SIZE] != 0)
+ return -EINVAL; /* Too long string */
+
+ return 0;
+}
+
+/*
+ * Display the mount options in /proc/mounts.
+ */
+static int cfs_show_options(struct seq_file *m, struct dentry *root)
+{
+ struct cfs_info *fsi = root->d_sb->s_fs_info;
+
+ if (fsi->base_path)
+ seq_show_option(m, "basedir", fsi->base_path);
+ if (fsi->has_digest)
+ seq_printf(m, ",digest=%*phN", SHA256_DIGEST_SIZE, fsi->digest);
+ if (fsi->verity_check != 0)
+ seq_printf(m, ",verity_check=%u", fsi->verity_check);
+
+ return 0;
+}
+
+static struct kmem_cache *cfs_inode_cachep;
+
+static struct inode *cfs_alloc_inode(struct super_block *sb)
+{
+ struct cfs_inode *cino = alloc_inode_sb(sb, cfs_inode_cachep, GFP_KERNEL);
+
+ if (!cino)
+ return NULL;
+
+ memset((u8 *)cino + sizeof(struct inode), 0,
+ sizeof(struct cfs_inode) - sizeof(struct inode));
+
+ return &cino->vfs_inode;
+}
+
+static void cfs_destroy_inode(struct inode *inode)
+{
+ struct cfs_inode *cino = CFS_I(inode);
+
+ cfs_inode_data_put(&cino->inode_data);
+}
+
+static void cfs_free_inode(struct inode *inode)
+{
+ struct cfs_inode *cino = CFS_I(inode);
+
+ kmem_cache_free(cfs_inode_cachep, cino);
+}
+
+static void cfs_put_super(struct super_block *sb)
+{
+ struct cfs_info *fsi = sb->s_fs_info;
+
+ cfs_ctx_put(&fsi->cfs_ctx);
+ if (fsi->bases) {
+ kern_unmount_array(fsi->bases, fsi->n_bases);
+ kfree(fsi->bases);
+ }
+ kfree(fsi->base_path);
+
+ kfree(fsi);
+}
+
+static int cfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+ struct cfs_info *fsi = dentry->d_sb->s_fs_info;
+ int err = 0;
+
+ /* We return the free space, etc from the first base dir. */
+ if (fsi->n_bases > 0) {
+ struct path root = { .mnt = fsi->bases[0],
+ .dentry = fsi->bases[0]->mnt_root };
+ err = vfs_statfs(&root, buf);
+ }
+
+ if (!err) {
+ buf->f_namelen = NAME_MAX;
+ buf->f_type = dentry->d_sb->s_magic;
+ }
+
+ return err;
+}
+
+static const struct super_operations cfs_ops = {
+ .statfs = cfs_statfs,
+ .drop_inode = generic_delete_inode,
+ .show_options = cfs_show_options,
+ .put_super = cfs_put_super,
+ .destroy_inode = cfs_destroy_inode,
+ .alloc_inode = cfs_alloc_inode,
+ .free_inode = cfs_free_inode,
+};
+
+enum cfs_param {
+ Opt_base_path,
+ Opt_digest,
+ Opt_verity_check,
+};
+
+const struct fs_parameter_spec cfs_parameters[] = {
+ fsparam_string("basedir", Opt_base_path),
+ fsparam_string("digest", Opt_digest),
+ fsparam_u32("verity_check", Opt_verity_check),
+ {}
+};
+
+static int cfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+ struct cfs_info *fsi = fc->s_fs_info;
+ struct fs_parse_result result;
+ int opt, r;
+
+ opt = fs_parse(fc, cfs_parameters, param, &result);
+ if (opt == -ENOPARAM)
+ return vfs_parse_fs_param_source(fc, param);
+ if (opt < 0)
+ return opt;
+
+ switch (opt) {
+ case Opt_base_path:
+ kfree(fsi->base_path);
+ /* Take ownership. */
+ fsi->base_path = param->string;
+ param->string = NULL;
+ break;
+ case Opt_digest:
+ r = digest_from_string(param->string, fsi->digest);
+ if (r < 0)
+ return r;
+ fsi->has_digest = true;
+ fsi->verity_check = 2; /* Default to full verity check */
+ break;
+ case Opt_verity_check:
+ if (result.uint_32 > 2)
+ return invalfc(fc, "Invalid verity_check mode");
+ fsi->verity_check = result.uint_32;
+ break;
+ }
+
+ return 0;
+}
+
+static struct vfsmount *resolve_basedir(const char *name)
+{
+ struct path path = {};
+ struct vfsmount *mnt;
+ int err = -EINVAL;
+
+ if (!*name) {
+ pr_err("empty basedir\n");
+ goto out;
+ }
+ err = kern_path(name, LOOKUP_FOLLOW, &path);
+ if (err) {
+ pr_err("failed to resolve '%s': %i\n", name, err);
+ goto out;
+ }
+
+ mnt = clone_private_mount(&path);
+ err = PTR_ERR(mnt);
+ if (IS_ERR(mnt)) {
+ pr_err("failed to clone basedir\n");
+ goto out_put;
+ }
+
+ path_put(&path);
+
+ /* Don't inherit atime flags */
+ mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
+
+ return mnt;
+
+out_put:
+ path_put(&path);
+out:
+ return ERR_PTR(err);
+}
+
+static int cfs_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+ struct cfs_info *fsi = sb->s_fs_info;
+ struct vfsmount **bases = NULL;
+ size_t numbasedirs = 0;
+ struct inode *inode;
+ struct vfsmount *mnt;
+ int ret;
+
+ if (sb->s_root)
+ return -EINVAL;
+
+ /* Set up the inode allocator early */
+ sb->s_op = &cfs_ops;
+ sb->s_flags |= SB_RDONLY;
+ sb->s_magic = CFS_MAGIC;
+ sb->s_xattr = cfs_xattr_handlers;
+ sb->s_export_op = &cfs_export_operations;
+
+ if (fsi->base_path) {
+ char *lower, *splitlower = NULL;
+
+ ret = -ENOMEM;
+ splitlower = kstrdup(fsi->base_path, GFP_KERNEL);
+ if (!splitlower)
+ goto fail;
+
+ ret = -EINVAL;
+ numbasedirs = cfs_split_basedirs(splitlower);
+ if (numbasedirs > CFS_MAX_STACK) {
+ pr_err("too many lower directories, limit is %d\n",
+ CFS_MAX_STACK);
+ kfree(splitlower);
+ goto fail;
+ }
+
+ ret = -ENOMEM;
+ bases = kcalloc(numbasedirs, sizeof(struct vfsmount *), GFP_KERNEL);
+ if (!bases) {
+ kfree(splitlower);
+ goto fail;
+ }
+
+ lower = splitlower;
+ for (size_t i = 0; i < numbasedirs; i++) {
+ mnt = resolve_basedir(lower);
+ if (IS_ERR(mnt)) {
+ ret = PTR_ERR(mnt);
+ kfree(splitlower);
+ goto fail;
+ }
+ bases[i] = mnt;
+
+ lower = strchr(lower, '\0') + 1;
+ }
+ kfree(splitlower);
+ }
+
+ /* Must be inited before calling cfs_get_inode. */
+ ret = cfs_init_ctx(fc->source, fsi->has_digest ? fsi->digest : NULL,
+ &fsi->cfs_ctx);
+ if (ret < 0)
+ goto fail;
+
+ inode = cfs_get_root_inode(sb);
+ if (IS_ERR(inode)) {
+ ret = PTR_ERR(inode);
+ goto fail;
+ }
+ sb->s_root = d_make_root(inode);
+
+ ret = -ENOMEM;
+ if (!sb->s_root)
+ goto fail;
+
+ sb->s_maxbytes = MAX_LFS_FILESIZE;
+ sb->s_blocksize = PAGE_SIZE;
+ sb->s_blocksize_bits = PAGE_SHIFT;
+
+ sb->s_time_gran = 1;
+
+ fsi->bases = bases;
+ fsi->n_bases = numbasedirs;
+ return 0;
+fail:
+ if (bases) {
+ for (size_t i = 0; i < numbasedirs; i++) {
+ if (bases[i])
+ kern_unmount(bases[i]);
+ }
+ kfree(bases);
+ }
+ cfs_ctx_put(&fsi->cfs_ctx);
+ return ret;
+}
+
+static int cfs_get_tree(struct fs_context *fc)
+{
+ return get_tree_nodev(fc, cfs_fill_super);
+}
+
+static const struct fs_context_operations cfs_context_ops = {
+ .parse_param = cfs_parse_param,
+ .get_tree = cfs_get_tree,
+};
+
+static struct file *open_base_file(struct cfs_info *fsi, struct inode *inode,
+ struct file *file)
+{
+ struct cfs_inode *cino = CFS_I(inode);
+ struct file *real_file;
+ char *real_path = cino->inode_data.path_payload;
+
+ for (size_t i = 0; i < fsi->n_bases; i++) {
+ real_file = file_open_root_mnt(fsi->bases[i], real_path,
+ file->f_flags, 0);
+ if (!IS_ERR(real_file) || PTR_ERR(real_file) != -ENOENT)
+ return real_file;
+ }
+
+ return ERR_PTR(-ENOENT);
+}
+
+static int cfs_open_file(struct inode *inode, struct file *file)
+{
+ struct cfs_info *fsi = inode->i_sb->s_fs_info;
+ struct cfs_inode *cino = CFS_I(inode);
+ char *real_path = cino->inode_data.path_payload;
+ struct file *faked_file;
+ struct file *real_file;
+
+ if (WARN_ON(!file))
+ return -EIO;
+
+ if (file->f_flags & (O_WRONLY | O_RDWR | O_CREAT | O_EXCL | O_TRUNC))
+ return -EROFS;
+
+ if (!real_path) {
+ file->private_data = &empty_file;
+ return 0;
+ }
+
+ if (fsi->verity_check >= 2 && !cino->inode_data.has_digest) {
+ pr_warn("WARNING: composefs image file '%pd' specified no fs-verity digest\n",
+ file->f_path.dentry);
+ return -EIO;
+ }
+
+ real_file = open_base_file(fsi, inode, file);
+
+ if (IS_ERR(real_file))
+ return PTR_ERR(real_file);
+
+ /* If metadata records a digest for the file, ensure it is there
+ * and correct before using the contents.
+ */
+ if (cino->inode_data.has_digest && fsi->verity_check >= 1) {
+ u8 verity_digest[FS_VERITY_MAX_DIGEST_SIZE];
+ enum hash_algo verity_algo;
+ int res;
+
+ res = fsverity_get_digest(d_inode(real_file->f_path.dentry),
+ verity_digest, &verity_algo);
+ if (res < 0) {
+ pr_warn("WARNING: composefs backing file '%pd' has no fs-verity digest\n",
+ real_file->f_path.dentry);
+ fput(real_file);
+ return -EIO;
+ }
+ if (verity_algo != HASH_ALGO_SHA256 ||
+ memcmp(cino->inode_data.digest, verity_digest,
+ SHA256_DIGEST_SIZE) != 0) {
+ pr_warn("WARNING: composefs backing file '%pd' has the wrong fs-verity digest\n",
+ real_file->f_path.dentry);
+ fput(real_file);
+ return -EIO;
+ }
+ }
+
+ faked_file = open_with_fake_path(&file->f_path, file->f_flags,
+ real_file->f_inode, current_cred());
+ fput(real_file);
+
+ if (IS_ERR(faked_file))
+ return PTR_ERR(faked_file);
+
+ file->private_data = faked_file;
+ return 0;
+}
+
+#ifdef CONFIG_MMU
+static unsigned long cfs_mmu_get_unmapped_area(struct file *file, unsigned long addr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags)
+{
+ struct file *realfile = file->private_data;
+
+ if (realfile == &empty_file)
+ return 0;
+
+ return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
+}
+#endif
+
+static int cfs_release_file(struct inode *inode, struct file *file)
+{
+ struct file *realfile = file->private_data;
+
+ if (WARN_ON(!realfile))
+ return -EIO;
+
+ if (realfile == &empty_file)
+ return 0;
+
+ fput(file->private_data);
+
+ return 0;
+}
+
+static int cfs_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ struct file *realfile = file->private_data;
+ int ret;
+
+ if (realfile == &empty_file)
+ return 0;
+
+ if (!realfile->f_op->mmap)
+ return -ENODEV;
+
+ if (WARN_ON(file != vma->vm_file))
+ return -EIO;
+
+ vma_set_file(vma, realfile);
+
+ ret = call_mmap(vma->vm_file, vma);
+
+ return ret;
+}
+
+static ssize_t cfs_read_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+ struct file *file = iocb->ki_filp;
+ struct file *realfile = file->private_data;
+ int ret;
+
+ if (realfile == &empty_file)
+ return 0;
+
+ if (!realfile->f_op->read_iter)
+ return -ENODEV;
+
+ iocb->ki_filp = realfile;
+ ret = call_read_iter(realfile, iocb, iter);
+ iocb->ki_filp = file;
+
+ return ret;
+}
+
+static int cfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
+{
+ struct file *realfile = file->private_data;
+
+ if (realfile == &empty_file)
+ return 0;
+
+ return vfs_fadvise(realfile, offset, len, advice);
+}
+
+static int cfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
+ struct inode *parent)
+{
+ u32 generation;
+ int len = 3;
+ u64 nodeid;
+
+ if (*max_len < len) {
+ *max_len = len;
+ return FILEID_INVALID;
+ }
+
+ nodeid = inode->i_ino;
+ generation = inode->i_generation;
+
+ fh[0] = (u32)(nodeid >> 32);
+ fh[1] = (u32)(nodeid & 0xffffffff);
+ fh[2] = generation;
+
+ *max_len = len;
+
+ return FILEID_CFS;
+}
+
+static struct dentry *cfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type)
+{
+ struct cfs_info *fsi = sb->s_fs_info;
+ struct inode *ino;
+ u64 inode_index;
+ u32 generation;
+
+ if (fh_type != FILEID_CFS || fh_len < 3)
+ return NULL;
+
+ inode_index = (u64)(fid->raw[0]) << 32;
+ inode_index |= fid->raw[1];
+ generation = fid->raw[2];
+
+ ino = ilookup(sb, inode_index);
+ if (!ino) {
+ struct cfs_inode_s inode_buf;
+ struct cfs_inode_s *inode;
+
+ inode = cfs_get_ino_index(&fsi->cfs_ctx, inode_index, &inode_buf);
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
+
+ ino = cfs_make_inode(&fsi->cfs_ctx, sb, inode_index, inode, NULL);
+ if (IS_ERR(ino))
+ return ERR_CAST(ino);
+ }
+ if (ino->i_generation != generation) {
+ iput(ino);
+ return ERR_PTR(-ESTALE);
+ }
+ return d_obtain_alias(ino);
+}
+
+static struct dentry *cfs_fh_to_parent(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type)
+{
+ return ERR_PTR(-EACCES);
+}
+
+static int cfs_get_name(struct dentry *parent, char *name, struct dentry *child)
+{
+ WARN_ON_ONCE(1);
+ return -EIO;
+}
+
+static struct dentry *cfs_get_parent(struct dentry *dentry)
+{
+ WARN_ON_ONCE(1);
+ return ERR_PTR(-EIO);
+}
+
+static const struct export_operations cfs_export_operations = {
+ .fh_to_dentry = cfs_fh_to_dentry,
+ .fh_to_parent = cfs_fh_to_parent,
+ .encode_fh = cfs_encode_fh,
+ .get_parent = cfs_get_parent,
+ .get_name = cfs_get_name,
+};
+
+static int cfs_getxattr(const struct xattr_handler *handler,
+ struct dentry *unused2, struct inode *inode,
+ const char *name, void *value, size_t size)
+{
+ struct cfs_info *fsi = inode->i_sb->s_fs_info;
+ struct cfs_inode *cino = CFS_I(inode);
+
+ return cfs_get_xattr(&fsi->cfs_ctx, &cino->inode_data, name, value, size);
+}
+
+static ssize_t cfs_listxattr(struct dentry *dentry, char *names, size_t size)
+{
+ struct inode *inode = d_inode(dentry);
+ struct cfs_info *fsi = inode->i_sb->s_fs_info;
+ struct cfs_inode *cino = CFS_I(inode);
+
+ return cfs_list_xattrs(&fsi->cfs_ctx, &cino->inode_data, names, size);
+}
+
+static const struct file_operations cfs_file_operations = {
+ .read_iter = cfs_read_iter,
+ .mmap = cfs_mmap,
+ .fadvise = cfs_fadvise,
+ .fsync = noop_fsync,
+ .splice_read = generic_file_splice_read,
+ .llseek = generic_file_llseek,
+#ifdef CONFIG_MMU
+ .get_unmapped_area = cfs_mmu_get_unmapped_area,
+#endif
+ .release = cfs_release_file,
+ .open = cfs_open_file,
+};
+
+static const struct xattr_handler cfs_xattr_handler = {
+ .prefix = "", /* catch all */
+ .get = cfs_getxattr,
+};
+
+static const struct xattr_handler *cfs_xattr_handlers[] = {
+ &cfs_xattr_handler,
+ NULL,
+};
+
+static const struct inode_operations cfs_file_inode_operations = {
+ .setattr = simple_setattr,
+ .getattr = simple_getattr,
+
+ .listxattr = cfs_listxattr,
+};
+
+static int cfs_init_fs_context(struct fs_context *fc)
+{
+ struct cfs_info *fsi;
+
+ fsi = kzalloc(sizeof(*fsi), GFP_KERNEL);
+ if (!fsi)
+ return -ENOMEM;
+
+ fc->s_fs_info = fsi;
+ fc->ops = &cfs_context_ops;
+ return 0;
+}
+
+static struct file_system_type cfs_type = {
+ .owner = THIS_MODULE,
+ .name = "composefs",
+ .init_fs_context = cfs_init_fs_context,
+ .parameters = cfs_parameters,
+ .kill_sb = kill_anon_super,
+};
+
+static void cfs_inode_init_once(void *foo)
+{
+ struct cfs_inode *cino = foo;
+
+ inode_init_once(&cino->vfs_inode);
+}
+
+static int __init init_cfs(void)
+{
+ cfs_inode_cachep = kmem_cache_create(
+ "cfs_inode", sizeof(struct cfs_inode), 0,
+ (SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD | SLAB_ACCOUNT),
+ cfs_inode_init_once);
+ if (!cfs_inode_cachep)
+ return -ENOMEM;
+
+ return register_filesystem(&cfs_type);
+}
+
+static void __exit exit_cfs(void)
+{
+ unregister_filesystem(&cfs_type);
+
+ /* Ensure all RCU free inodes are safe to be destroyed. */
+ rcu_barrier();
+
+ kmem_cache_destroy(cfs_inode_cachep);
+}
+
+module_init(init_cfs);
+module_exit(exit_cfs);
--
2.39.0
