fs: port ->create() to pass mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8ae ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Christian Brauner (Microsoft) <[email protected]>

Documentation/filesystems/locking.rst

@@ -56,7 +56,7 @@ inode_operations
 
 prototypes::
 
-	int (*create) (struct inode *,struct dentry *,umode_t, bool);
+	int (*create) (struct mnt_idmap *, struct inode *,struct dentry *,umode_t, bool);
 	struct dentry * (*lookup) (struct inode *,struct dentry *, unsigned int);
 	int (*link) (struct dentry *,struct inode *,struct dentry *);
 	int (*unlink) (struct inode *,struct dentry *);

Documentation/filesystems/vfs.rst

@@ -421,7 +421,7 @@ As of kernel 2.6.22, the following members are defined:
 .. code-block:: c
 
 	struct inode_operations {
-		int (*create) (struct user_namespace *, struct inode *,struct dentry *, umode_t, bool);
+		int (*create) (struct mnt_idmap *, struct inode *,struct dentry *, umode_t, bool);
 		struct dentry * (*lookup) (struct inode *,struct dentry *, unsigned int);
 		int (*link) (struct dentry *,struct inode *,struct dentry *);
 		int (*unlink) (struct inode *,struct dentry *);

fs/9p/vfs_inode.c

@@ -672,7 +672,7 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
 
 /**
  * v9fs_vfs_create - VFS hook to create a regular file
- * @mnt_userns: The user namespace of the mount
+ * @idmap: idmap of the mount
  * @dir: The parent directory
  * @dentry: The name of file to be created
  * @mode: The UNIX file mode to set
@@ -684,7 +684,7 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
  */
 
 static int
-v9fs_vfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+v9fs_vfs_create(struct mnt_idmap *idmap, struct inode *dir,
 		struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);

fs/9p/vfs_inode_dotl.c

@@ -211,17 +211,18 @@ int v9fs_open_to_dotl_flags(int flags)
 
 /**
  * v9fs_vfs_create_dotl - VFS hook to create files for 9P2000.L protocol.
- * @mnt_userns: The user namespace of the mount
+ * @idmap: The user namespace of the mount
  * @dir: directory inode that is being created
  * @dentry:  dentry that is being deleted
  * @omode: create permissions
  * @excl: True if the file must not yet exist
  *
  */
 static int
-v9fs_vfs_create_dotl(struct user_namespace *mnt_userns, struct inode *dir,
+v9fs_vfs_create_dotl(struct mnt_idmap *idmap, struct inode *dir,
 		     struct dentry *dentry, umode_t omode, bool excl)
 {
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	return v9fs_vfs_mknod_dotl(mnt_userns, dir, dentry, omode, 0);
 }
 

fs/affs/affs.h

@@ -167,7 +167,7 @@ extern const struct export_operations affs_export_ops;
 extern int	affs_hash_name(struct super_block *sb, const u8 *name, unsigned int len);
 extern struct dentry *affs_lookup(struct inode *dir, struct dentry *dentry, unsigned int);
 extern int	affs_unlink(struct inode *dir, struct dentry *dentry);
-extern int	affs_create(struct user_namespace *mnt_userns, struct inode *dir,
+extern int	affs_create(struct mnt_idmap *idmap, struct inode *dir,
 			struct dentry *dentry, umode_t mode, bool);
 extern int	affs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 			struct dentry *dentry, umode_t mode);

fs/affs/namei.c

@@ -242,7 +242,7 @@ affs_unlink(struct inode *dir, struct dentry *dentry)
 }
 
 int
-affs_create(struct user_namespace *mnt_userns, struct inode *dir,
+affs_create(struct mnt_idmap *idmap, struct inode *dir,
 	    struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct super_block *sb = dir->i_sb;

fs/afs/dir.c

@@ -28,7 +28,7 @@ static bool afs_lookup_one_filldir(struct dir_context *ctx, const char *name, in
 				  loff_t fpos, u64 ino, unsigned dtype);
 static bool afs_lookup_filldir(struct dir_context *ctx, const char *name, int nlen,
 			      loff_t fpos, u64 ino, unsigned dtype);
-static int afs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int afs_create(struct mnt_idmap *idmap, struct inode *dir,
 		      struct dentry *dentry, umode_t mode, bool excl);
 static int afs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 		     struct dentry *dentry, umode_t mode);
@@ -1630,7 +1630,7 @@ static const struct afs_operation_ops afs_create_operation = {
 /*
  * create a regular file on an AFS filesystem
  */
-static int afs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int afs_create(struct mnt_idmap *idmap, struct inode *dir,
 		      struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct afs_operation *op;

fs/bad_inode.c

@@ -27,7 +27,7 @@ static const struct file_operations bad_file_ops =
 	.open		= bad_file_open,
 };
 
-static int bad_inode_create(struct user_namespace *mnt_userns,
+static int bad_inode_create(struct mnt_idmap *idmap,
 			    struct inode *dir, struct dentry *dentry,
 			    umode_t mode, bool excl)
 {

fs/bfs/dir.c

@@ -75,7 +75,7 @@ const struct file_operations bfs_dir_operations = {
 	.llseek		= generic_file_llseek,
 };
 
-static int bfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int bfs_create(struct mnt_idmap *idmap, struct inode *dir,
 		      struct dentry *dentry, umode_t mode, bool excl)
 {
 	int err;

fs/btrfs/inode.c

@@ -6739,9 +6739,10 @@ static int btrfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 	return btrfs_create_common(dir, dentry, inode);
 }
 
-static int btrfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int btrfs_create(struct mnt_idmap *idmap, struct inode *dir,
 			struct dentry *dentry, umode_t mode, bool excl)
 {
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct inode *inode;
 
 	inode = new_inode(dir->i_sb);

fs/ceph/dir.c

@@ -905,9 +905,10 @@ static int ceph_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 	return err;
 }
 
-static int ceph_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int ceph_create(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, umode_t mode, bool excl)
 {
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	return ceph_mknod(mnt_userns, dir, dentry, mode, 0);
 }
 

fs/cifs/cifsfs.h

@@ -49,7 +49,7 @@ extern void cifs_sb_deactive(struct super_block *sb);
 /* Functions related to inodes */
 extern const struct inode_operations cifs_dir_inode_ops;
 extern struct inode *cifs_root_iget(struct super_block *);
-extern int cifs_create(struct user_namespace *, struct inode *,
+extern int cifs_create(struct mnt_idmap *, struct inode *,
 		       struct dentry *, umode_t, bool excl);
 extern int cifs_atomic_open(struct inode *, struct dentry *,
 			    struct file *, unsigned, umode_t);

fs/cifs/dir.c

@@ -529,7 +529,7 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
 	return rc;
 }
 
-int cifs_create(struct user_namespace *mnt_userns, struct inode *inode,
+int cifs_create(struct mnt_idmap *idmap, struct inode *inode,
 		struct dentry *direntry, umode_t mode, bool excl)
 {
 	int rc;

fs/coda/dir.c

@@ -133,7 +133,7 @@ static inline void coda_dir_drop_nlink(struct inode *dir)
 }
 
 /* creation routines: create, mknod, mkdir, link, symlink */
-static int coda_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int coda_create(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *de, umode_t mode, bool excl)
 {
 	int error;

fs/ecryptfs/inode.c

@@ -253,7 +253,7 @@ int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry,
  * Returns zero on success; non-zero on error condition
  */
 static int
-ecryptfs_create(struct user_namespace *mnt_userns,
+ecryptfs_create(struct mnt_idmap *idmap,
 		struct inode *directory_inode, struct dentry *ecryptfs_dentry,
 		umode_t mode, bool excl)
 {

fs/efivarfs/inode.c

@@ -70,7 +70,7 @@ bool efivarfs_valid_name(const char *str, int len)
 	return uuid_is_valid(s);
 }
 
-static int efivarfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int efivarfs_create(struct mnt_idmap *idmap, struct inode *dir,
 			   struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct inode *inode = NULL;

fs/exfat/namei.c

@@ -551,7 +551,7 @@ static int exfat_add_entry(struct inode *inode, const char *path,
 	return ret;
 }
 
-static int exfat_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int exfat_create(struct mnt_idmap *idmap, struct inode *dir,
 			struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct super_block *sb = dir->i_sb;

fs/ext2/namei.c

@@ -99,7 +99,7 @@ struct dentry *ext2_get_parent(struct dentry *child)
  * If the create succeeds, we fill in the inode information
  * with d_instantiate(). 
  */
-static int ext2_create (struct user_namespace * mnt_userns,
+static int ext2_create (struct mnt_idmap * idmap,
 			struct inode * dir, struct dentry * dentry,
 			umode_t mode, bool excl)
 {

fs/ext4/namei.c

@@ -2792,9 +2792,10 @@ static int ext4_add_nondir(handle_t *handle,
  * If the create succeeds, we fill in the inode information
  * with d_instantiate().
  */
-static int ext4_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int ext4_create(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, umode_t mode, bool excl)
 {
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	handle_t *handle;
 	struct inode *inode;
 	int err, credits, retries = 0;

fs/f2fs/namei.c

@@ -333,9 +333,10 @@ static struct inode *f2fs_new_inode(struct user_namespace *mnt_userns,
 	return ERR_PTR(err);
 }
 
-static int f2fs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int f2fs_create(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, umode_t mode, bool excl)
 {
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
 	struct inode *inode;
 	nid_t ino = 0;

fs/fat/namei_msdos.c

@@ -261,7 +261,7 @@ static int msdos_add_entry(struct inode *dir, const unsigned char *name,
 }
 
 /***** Create a file */
-static int msdos_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int msdos_create(struct mnt_idmap *idmap, struct inode *dir,
 			struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct super_block *sb = dir->i_sb;

fs/fat/namei_vfat.c

@@ -756,7 +756,7 @@ static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry,
 	return ERR_PTR(err);
 }
 
-static int vfat_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int vfat_create(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct super_block *sb = dir->i_sb;

fs/fuse/dir.c

@@ -796,7 +796,7 @@ static int fuse_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 	return create_new_entry(fm, &args, dir, entry, mode);
 }
 
-static int fuse_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int fuse_create(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *entry, umode_t mode, bool excl)
 {
 	return fuse_mknod(&init_user_ns, dir, entry, mode, 0);

fs/gfs2/inode.c

@@ -843,7 +843,7 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 
 /**
  * gfs2_create - Create a file
- * @mnt_userns: User namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @dir: The directory in which to create the file
  * @dentry: The dentry of the new file
  * @mode: The mode of the new file
@@ -852,7 +852,7 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
  * Returns: errno
  */
 
-static int gfs2_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int gfs2_create(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, umode_t mode, bool excl)
 {
 	return gfs2_create_inode(dir, dentry, NULL, S_IFREG | mode, 0, NULL, 0, excl);

fs/hfs/dir.c

@@ -189,7 +189,7 @@ static int hfs_dir_release(struct inode *inode, struct file *file)
  * a directory and return a corresponding inode, given the inode for
  * the directory and the name (and its length) of the new file.
  */
-static int hfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int hfs_create(struct mnt_idmap *idmap, struct inode *dir,
 		      struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct inode *inode;

fs/hfsplus/dir.c

@@ -517,7 +517,7 @@ static int hfsplus_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 	return res;
 }
 
-static int hfsplus_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int hfsplus_create(struct mnt_idmap *idmap, struct inode *dir,
 			  struct dentry *dentry, umode_t mode, bool excl)
 {
 	return hfsplus_mknod(&init_user_ns, dir, dentry, mode, 0);

fs/hostfs/hostfs_kern.c

@@ -559,7 +559,7 @@ static int read_name(struct inode *ino, char *name)
 	return 0;
 }
 
-static int hostfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int hostfs_create(struct mnt_idmap *idmap, struct inode *dir,
 			 struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct inode *inode;

fs/hpfs/namei.c

@@ -129,7 +129,7 @@ static int hpfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 	return err;
 }
 
-static int hpfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int hpfs_create(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, umode_t mode, bool excl)
 {
 	const unsigned char *name = dentry->d_name.name;

fs/hugetlbfs/inode.c

@@ -1043,7 +1043,7 @@ static int hugetlbfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 	return retval;
 }
 
-static int hugetlbfs_create(struct user_namespace *mnt_userns,
+static int hugetlbfs_create(struct mnt_idmap *idmap,
 			    struct inode *dir, struct dentry *dentry,
 			    umode_t mode, bool excl)
 {

fs/jffs2/dir.c

@@ -24,7 +24,7 @@
 
 static int jffs2_readdir (struct file *, struct dir_context *);
 
-static int jffs2_create (struct user_namespace *, struct inode *,
+static int jffs2_create (struct mnt_idmap *, struct inode *,
 		         struct dentry *, umode_t, bool);
 static struct dentry *jffs2_lookup (struct inode *,struct dentry *,
 				    unsigned int);
@@ -160,7 +160,7 @@ static int jffs2_readdir(struct file *file, struct dir_context *ctx)
 /***********************************************************************/
 
 
-static int jffs2_create(struct user_namespace *mnt_userns, struct inode *dir_i,
+static int jffs2_create(struct mnt_idmap *idmap, struct inode *dir_i,
 			struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct jffs2_raw_inode *ri;

fs/jfs/namei.c

@@ -59,7 +59,7 @@ static inline void free_ea_wmap(struct inode *inode)
  * RETURN:	Errors from subroutines
  *
  */
-static int jfs_create(struct user_namespace *mnt_userns, struct inode *dip,
+static int jfs_create(struct mnt_idmap *idmap, struct inode *dip,
 		      struct dentry *dentry, umode_t mode, bool excl)
 {
 	int rc = 0;

fs/minix/namei.c

@@ -65,10 +65,10 @@ static int minix_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 	return finish_open_simple(file, error);
 }
 
-static int minix_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int minix_create(struct mnt_idmap *idmap, struct inode *dir,
 			struct dentry *dentry, umode_t mode, bool excl)
 {
-	return minix_mknod(mnt_userns, dir, dentry, mode, 0);
+	return minix_mknod(&init_user_ns, dir, dentry, mode, 0);
 }
 
 static int minix_symlink(struct user_namespace *mnt_userns, struct inode *dir,

fs/namei.c

@@ -3115,7 +3115,7 @@ int vfs_create(struct mnt_idmap *idmap, struct inode *dir,
 	error = security_inode_create(dir, dentry, mode);
 	if (error)
 		return error;
-	error = dir->i_op->create(mnt_userns, dir, dentry, mode, want_excl);
+	error = dir->i_op->create(idmap, dir, dentry, mode, want_excl);
 	if (!error)
 		fsnotify_create(dir, dentry);
 	return error;
@@ -3322,6 +3322,7 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
 				  const struct open_flags *op,
 				  bool got_write)
 {
+	struct mnt_idmap *idmap;
 	struct user_namespace *mnt_userns;
 	struct dentry *dir = nd->path.dentry;
 	struct inode *dir_inode = dir->d_inode;
@@ -3370,7 +3371,8 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
 	 */
 	if (unlikely(!got_write))
 		open_flag &= ~O_TRUNC;
-	mnt_userns = mnt_user_ns(nd->path.mnt);
+	idmap = mnt_idmap(nd->path.mnt);
+	mnt_userns = mnt_idmap_owner(idmap);
 	if (open_flag & O_CREAT) {
 		if (open_flag & O_EXCL)
 			open_flag &= ~O_TRUNC;
@@ -3413,7 +3415,7 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
 			goto out_dput;
 		}
 
-		error = dir_inode->i_op->create(mnt_userns, dir_inode, dentry,
+		error = dir_inode->i_op->create(idmap, dir_inode, dentry,
 						mode, open_flag & O_EXCL);
 		if (error)
 			goto out_dput;

fs/nfs/dir.c

@@ -2296,7 +2296,7 @@ EXPORT_SYMBOL_GPL(nfs_instantiate);
  * that the operation succeeded on the server, but an error in the
  * reply path made it appear to have failed.
  */
-int nfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+int nfs_create(struct mnt_idmap *idmap, struct inode *dir,
 	       struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct iattr attr;