new helper: set_default_d_op()

... to be used instead of manually assigning to ->s_d_op.
All in-tree filesystem converted (and field itself is renamed,
so any out-of-tree ones in need of conversion will be caught
by compiler).

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Documentation/filesystems/porting.rst

@@ -1249,3 +1249,10 @@ Using try_lookup_noperm() will require linux/namei.h to be included.
 
 Calling conventions for ->d_automount() have changed; we should *not* grab
 an extra reference to new mount - it should be returned with refcount 1.
+
+---
+
+**mandatory**
+
+If your filesystem sets the default dentry_operations, use set_default_d_op()
+rather than manually setting sb->s_d_op.

fs/9p/vfs_super.c

@@ -135,9 +135,9 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
 		goto release_sb;
 
 	if (v9ses->cache & (CACHE_META|CACHE_LOOSE))
-		sb->s_d_op = &v9fs_cached_dentry_operations;
+		set_default_d_op(sb, &v9fs_cached_dentry_operations);
 	else
-		sb->s_d_op = &v9fs_dentry_operations;
+		set_default_d_op(sb, &v9fs_dentry_operations);
 
 	inode = v9fs_get_new_inode_from_fid(v9ses, fid, sb);
 	if (IS_ERR(inode)) {

fs/adfs/super.c

@@ -397,7 +397,7 @@ static int adfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	if (asb->s_ftsuffix)
 		asb->s_namelen += 4;
 
-	sb->s_d_op = &adfs_dentry_operations;
+	set_default_d_op(sb, &adfs_dentry_operations);
 	root = adfs_iget(sb, &root_obj);
 	sb->s_root = d_make_root(root);
 	if (!sb->s_root) {

fs/affs/super.c

@@ -500,9 +500,9 @@ static int affs_fill_super(struct super_block *sb, struct fs_context *fc)
 		return PTR_ERR(root_inode);
 
 	if (affs_test_opt(AFFS_SB(sb)->s_flags, SF_INTL))
-		sb->s_d_op = &affs_intl_dentry_operations;
+		set_default_d_op(sb, &affs_intl_dentry_operations);
 	else
-		sb->s_d_op = &affs_dentry_operations;
+		set_default_d_op(sb, &affs_dentry_operations);
 
 	sb->s_root = d_make_root(root_inode);
 	if (!sb->s_root) {

fs/afs/super.c

@@ -483,9 +483,9 @@ static int afs_fill_super(struct super_block *sb, struct afs_fs_context *ctx)
 		goto error;
 
 	if (as->dyn_root) {
-		sb->s_d_op = &afs_dynroot_dentry_operations;
+		set_default_d_op(sb, &afs_dynroot_dentry_operations);
 	} else {
-		sb->s_d_op = &afs_fs_dentry_operations;
+		set_default_d_op(sb, &afs_fs_dentry_operations);
 		rcu_assign_pointer(as->volume->sb, sb);
 	}
 

fs/autofs/inode.c

@@ -311,7 +311,7 @@ static int autofs_fill_super(struct super_block *s, struct fs_context *fc)
 	s->s_blocksize_bits = 10;
 	s->s_magic = AUTOFS_SUPER_MAGIC;
 	s->s_op = &autofs_sops;
-	s->s_d_op = &autofs_dentry_operations;
+	set_default_d_op(s, &autofs_dentry_operations);
 	s->s_time_gran = 1;
 
 	/*

fs/btrfs/super.c

@@ -950,7 +950,7 @@ static int btrfs_fill_super(struct super_block *sb,
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	sb->s_magic = BTRFS_SUPER_MAGIC;
 	sb->s_op = &btrfs_super_ops;
-	sb->s_d_op = &btrfs_dentry_operations;
+	set_default_d_op(sb, &btrfs_dentry_operations);
 	sb->s_export_op = &btrfs_export_ops;
 #ifdef CONFIG_FS_VERITY
 	sb->s_vop = &btrfs_verityops;

fs/ceph/super.c

@@ -1219,7 +1219,7 @@ static int ceph_set_super(struct super_block *s, struct fs_context *fc)
 	fsc->max_file_size = 1ULL << 40; /* temp value until we get mdsmap */
 
 	s->s_op = &ceph_super_ops;
-	s->s_d_op = &ceph_dentry_ops;
+	set_default_d_op(s, &ceph_dentry_ops);
 	s->s_export_op = &ceph_export_ops;
 
 	s->s_time_gran = 1;

fs/coda/inode.c

@@ -230,7 +230,7 @@ static int coda_fill_super(struct super_block *sb, struct fs_context *fc)
 	sb->s_blocksize_bits = 12;
 	sb->s_magic = CODA_SUPER_MAGIC;
 	sb->s_op = &coda_super_operations;
-	sb->s_d_op = &coda_dentry_operations;
+	set_default_d_op(sb, &coda_dentry_operations);
 	sb->s_time_gran = 1;
 	sb->s_time_min = S64_MIN;
 	sb->s_time_max = S64_MAX;

fs/configfs/mount.c

@@ -92,7 +92,7 @@ static int configfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	configfs_root_group.cg_item.ci_dentry = root;
 	root->d_fsdata = &configfs_root;
 	sb->s_root = root;
-	sb->s_d_op = &configfs_dentry_ops; /* the rest get that */
+	set_default_d_op(sb, &configfs_dentry_ops); /* the rest get that */
 	return 0;
 }
 

fs/dcache.c

@@ -1738,7 +1738,7 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
 	INIT_HLIST_HEAD(&dentry->d_children);
 	INIT_HLIST_NODE(&dentry->d_u.d_alias);
 	INIT_HLIST_NODE(&dentry->d_sib);
-	d_set_d_op(dentry, dentry->d_sb->s_d_op);
+	d_set_d_op(dentry, dentry->d_sb->__s_d_op);
 
 	if (dentry->d_op && dentry->d_op->d_init) {
 		err = dentry->d_op->d_init(dentry);
@@ -1821,7 +1821,7 @@ struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
 	struct dentry *dentry = __d_alloc(sb, name);
 	if (likely(dentry)) {
 		dentry->d_flags |= DCACHE_NORCU;
-		if (!sb->s_d_op)
+		if (!dentry->d_op)
 			d_set_d_op(dentry, &anon_ops);
 	}
 	return dentry;
@@ -1867,6 +1867,12 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
 }
 EXPORT_SYMBOL(d_set_d_op);
 
+void set_default_d_op(struct super_block *s, const struct dentry_operations *ops)
+{
+	s->__s_d_op = ops;
+}
+EXPORT_SYMBOL(set_default_d_op);
+
 static unsigned d_flags_for_inode(struct inode *inode)
 {
 	unsigned add_flags = DCACHE_REGULAR_TYPE;

fs/debugfs/inode.c

@@ -273,7 +273,7 @@ static int debugfs_fill_super(struct super_block *sb, struct fs_context *fc)
 		return err;
 
 	sb->s_op = &debugfs_super_operations;
-	sb->s_d_op = &debugfs_dops;
+	set_default_d_op(sb, &debugfs_dops);
 
 	debugfs_apply_options(sb);
 

fs/devpts/inode.c

@@ -381,7 +381,7 @@ static int devpts_fill_super(struct super_block *s, struct fs_context *fc)
 	s->s_blocksize_bits = 10;
 	s->s_magic = DEVPTS_SUPER_MAGIC;
 	s->s_op = &devpts_sops;
-	s->s_d_op = &simple_dentry_operations;
+	set_default_d_op(s, &simple_dentry_operations);
 	s->s_time_gran = 1;
 	fsi->sb = s;
 

fs/ecryptfs/main.c

@@ -471,7 +471,7 @@ static int ecryptfs_get_tree(struct fs_context *fc)
 	sbi = NULL;
 	s->s_op = &ecryptfs_sops;
 	s->s_xattr = ecryptfs_xattr_handlers;
-	s->s_d_op = &ecryptfs_dops;
+	set_default_d_op(s, &ecryptfs_dops);
 
 	err = "Reading sb failed";
 	rc = kern_path(fc->source, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);

fs/efivarfs/super.c

@@ -350,7 +350,7 @@ static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	sb->s_blocksize_bits    = PAGE_SHIFT;
 	sb->s_magic             = EFIVARFS_MAGIC;
 	sb->s_op                = &efivarfs_ops;
-	sb->s_d_op		= &efivarfs_d_ops;
+	set_default_d_op(sb, &efivarfs_d_ops);
 	sb->s_time_gran         = 1;
 
 	if (!efivar_supports_writes())

fs/exfat/super.c

@@ -667,9 +667,9 @@ static int exfat_fill_super(struct super_block *sb, struct fs_context *fc)
 	}
 
 	if (sbi->options.utf8)
-		sb->s_d_op = &exfat_utf8_dentry_ops;
+		set_default_d_op(sb, &exfat_utf8_dentry_ops);
 	else
-		sb->s_d_op = &exfat_dentry_ops;
+		set_default_d_op(sb, &exfat_dentry_ops);
 
 	root_inode = new_inode(sb);
 	if (!root_inode) {

fs/fat/namei_msdos.c

@@ -646,7 +646,7 @@ static const struct inode_operations msdos_dir_inode_operations = {
 static void setup(struct super_block *sb)
 {
 	MSDOS_SB(sb)->dir_ops = &msdos_dir_inode_operations;
-	sb->s_d_op = &msdos_dentry_operations;
+	set_default_d_op(sb, &msdos_dentry_operations);
 	sb->s_flags |= SB_NOATIME;
 }
 

fs/fat/namei_vfat.c

@@ -1187,9 +1187,9 @@ static void setup(struct super_block *sb)
 {
 	MSDOS_SB(sb)->dir_ops = &vfat_dir_inode_operations;
 	if (MSDOS_SB(sb)->options.name_check != 's')
-		sb->s_d_op = &vfat_ci_dentry_ops;
+		set_default_d_op(sb, &vfat_ci_dentry_ops);
 	else
-		sb->s_d_op = &vfat_dentry_ops;
+		set_default_d_op(sb, &vfat_dentry_ops);
 }
 
 static int vfat_fill_super(struct super_block *sb, struct fs_context *fc)

fs/fuse/inode.c

@@ -1715,7 +1715,7 @@ static int fuse_fill_super_submount(struct super_block *sb,
 	fi = get_fuse_inode(root);
 	fi->nlookup--;
 
-	sb->s_d_op = &fuse_dentry_operations;
+	set_default_d_op(sb, &fuse_dentry_operations);
 	sb->s_root = d_make_root(root);
 	if (!sb->s_root)
 		return -ENOMEM;
@@ -1850,7 +1850,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
 
 	err = -ENOMEM;
 	root = fuse_get_root_inode(sb, ctx->rootmode);
-	sb->s_d_op = &fuse_dentry_operations;
+	set_default_d_op(sb, &fuse_dentry_operations);
 	root_dentry = d_make_root(root);
 	if (!root_dentry)
 		goto err_dev_free;

fs/gfs2/ops_fstype.c

@@ -1145,7 +1145,7 @@ static int gfs2_fill_super(struct super_block *sb, struct fs_context *fc)
 	sb->s_magic = GFS2_MAGIC;
 	sb->s_op = &gfs2_super_ops;
 
-	sb->s_d_op = &gfs2_dops;
+	set_default_d_op(sb, &gfs2_dops);
 	sb->s_export_op = &gfs2_export_ops;
 	sb->s_qcop = &gfs2_quotactl_ops;
 	sb->s_quota_types = QTYPE_MASK_USR | QTYPE_MASK_GRP;

fs/hfs/super.c

@@ -365,7 +365,7 @@ static int hfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	if (!root_inode)
 		goto bail_no_root;
 
-	sb->s_d_op = &hfs_dentry_operations;
+	set_default_d_op(sb, &hfs_dentry_operations);
 	res = -ENOMEM;
 	sb->s_root = d_make_root(root_inode);
 	if (!sb->s_root)

fs/hfsplus/super.c

@@ -508,7 +508,7 @@ static int hfsplus_fill_super(struct super_block *sb, struct fs_context *fc)
 		goto out_put_alloc_file;
 	}
 
-	sb->s_d_op = &hfsplus_dentry_operations;
+	set_default_d_op(sb, &hfsplus_dentry_operations);
 	sb->s_root = d_make_root(root);
 	if (!sb->s_root) {
 		err = -ENOMEM;

fs/hostfs/hostfs_kern.c

@@ -933,7 +933,7 @@ static int hostfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	sb->s_blocksize_bits = 10;
 	sb->s_magic = HOSTFS_SUPER_MAGIC;
 	sb->s_op = &hostfs_sbops;
-	sb->s_d_op = &simple_dentry_operations;
+	set_default_d_op(sb, &simple_dentry_operations);
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	err = super_setup_bdi(sb);
 	if (err)

fs/hpfs/super.c

@@ -554,7 +554,7 @@ static int hpfs_fill_super(struct super_block *s, struct fs_context *fc)
 	/* Fill superblock stuff */
 	s->s_magic = HPFS_SUPER_MAGIC;
 	s->s_op = &hpfs_sops;
-	s->s_d_op = &hpfs_dentry_operations;
+	set_default_d_op(s, &hpfs_dentry_operations);
 	s->s_time_min =  local_to_gmt(s, 0);
 	s->s_time_max =  local_to_gmt(s, U32_MAX);
 

fs/isofs/inode.c

@@ -939,7 +939,7 @@ static int isofs_fill_super(struct super_block *s, struct fs_context *fc)
 	sbi->s_check = opt->check;
 
 	if (table)
-		s->s_d_op = &isofs_dentry_ops[table - 1];
+		set_default_d_op(s, &isofs_dentry_ops[table - 1]);
 
 	/* get the root dentry */
 	s->s_root = d_make_root(inode);

fs/jfs/super.c

@@ -542,7 +542,7 @@ static int jfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	sb->s_magic = JFS_SUPER_MAGIC;
 
 	if (sbi->mntflag & JFS_OS2)
-		sb->s_d_op = &jfs_ci_dentry_operations;
+		set_default_d_op(sb, &jfs_ci_dentry_operations);
 
 	inode = jfs_iget(sb, ROOT_I);
 	if (IS_ERR(inode)) {

fs/kernfs/mount.c

@@ -318,7 +318,7 @@ static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *k
 		return -ENOMEM;
 	}
 	sb->s_root = root;
-	sb->s_d_op = &kernfs_dops;
+	set_default_d_op(sb, &kernfs_dops);
 	return 0;
 }
 

fs/libfs.c

@@ -75,7 +75,7 @@ struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned
 {
 	if (dentry->d_name.len > NAME_MAX)
 		return ERR_PTR(-ENAMETOOLONG);
-	if (!dentry->d_sb->s_d_op)
+	if (!dentry->d_op)
 		d_set_d_op(dentry, &simple_dentry_operations);
 
 	if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
@@ -684,7 +684,7 @@ static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc)
 	s->s_root = d_make_root(root);
 	if (!s->s_root)
 		return -ENOMEM;
-	s->s_d_op = ctx->dops;
+	set_default_d_op(s, ctx->dops);
 	return 0;
 }
 
@@ -1950,22 +1950,22 @@ static const struct dentry_operations generic_encrypted_dentry_ops = {
  * @sb: superblock to be configured
  *
  * Filesystems supporting casefolding and/or fscrypt can call this
- * helper at mount-time to configure sb->s_d_op to best set of dentry
+ * helper at mount-time to configure default dentry_operations to the
- * operations required for the enabled features. The helper must be
+ * best set of dentry operations required for the enabled features.
- * called after these have been configured, but before the root dentry
+ * The helper must be called after these have been configured, but
- * is created.
+ * before the root dentry is created.
  */
 void generic_set_sb_d_ops(struct super_block *sb)
 {
 #if IS_ENABLED(CONFIG_UNICODE)
 	if (sb->s_encoding) {
-		sb->s_d_op = &generic_ci_dentry_ops;
+		set_default_d_op(sb, &generic_ci_dentry_ops);
 		return;
 	}
 #endif
 #ifdef CONFIG_FS_ENCRYPTION
 	if (sb->s_cop) {
-		sb->s_d_op = &generic_encrypted_dentry_ops;
+		set_default_d_op(sb, &generic_encrypted_dentry_ops);
 		return;
 	}
 #endif

fs/nfs/super.c

@@ -1183,7 +1183,7 @@ static int nfs_set_super(struct super_block *s, struct fs_context *fc)
 	struct nfs_server *server = fc->s_fs_info;
 	int ret;
 
-	s->s_d_op = server->nfs_client->rpc_ops->dentry_ops;
+	set_default_d_op(s, server->nfs_client->rpc_ops->dentry_ops);
 	ret = set_anon_super(s, server);
 	if (ret == 0)
 		server->s_dev = s->s_dev;

fs/ntfs3/super.c

@@ -1223,7 +1223,8 @@ static int ntfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	sb->s_export_op = &ntfs_export_ops;
 	sb->s_time_gran = NTFS_TIME_GRAN; // 100 nsec
 	sb->s_xattr = ntfs_xattr_handlers;
-	sb->s_d_op = options->nocase ? &ntfs_dentry_ops : NULL;
+	if (options->nocase)
+		set_default_d_op(sb, &ntfs_dentry_ops);
 
 	options->nls = ntfs_load_nls(options->nls_name);
 	if (IS_ERR(options->nls)) {

fs/ocfs2/super.c

@@ -1962,7 +1962,7 @@ static int ocfs2_initialize_super(struct super_block *sb,
 
 	sb->s_fs_info = osb;
 	sb->s_op = &ocfs2_sops;
-	sb->s_d_op = &ocfs2_dentry_ops;
+	set_default_d_op(sb, &ocfs2_dentry_ops);
 	sb->s_export_op = &ocfs2_export_ops;
 	sb->s_qcop = &dquot_quotactl_sysfile_ops;
 	sb->dq_op = &ocfs2_quota_operations;

fs/orangefs/super.c

@@ -416,7 +416,7 @@ static int orangefs_fill_sb(struct super_block *sb,
 	sb->s_xattr = orangefs_xattr_handlers;
 	sb->s_magic = ORANGEFS_SUPER_MAGIC;
 	sb->s_op = &orangefs_s_ops;
-	sb->s_d_op = &orangefs_dentry_operations;
+	set_default_d_op(sb, &orangefs_dentry_operations);
 
 	sb->s_blocksize = PAGE_SIZE;
 	sb->s_blocksize_bits = PAGE_SHIFT;

fs/overlayfs/super.c

@@ -1322,7 +1322,7 @@ int ovl_fill_super(struct super_block *sb, struct fs_context *fc)
 	if (WARN_ON(fc->user_ns != current_user_ns()))
 		goto out_err;
 
-	sb->s_d_op = &ovl_dentry_operations;
+	set_default_d_op(sb, &ovl_dentry_operations);
 
 	err = -ENOMEM;
 	if (!ofs->creator_cred)

fs/smb/client/cifsfs.c

@@ -260,9 +260,9 @@ cifs_read_super(struct super_block *sb)
 	}
 
 	if (tcon->nocase)
-		sb->s_d_op = &cifs_ci_dentry_ops;
+		set_default_d_op(sb, &cifs_ci_dentry_ops);
 	else
-		sb->s_d_op = &cifs_dentry_ops;
+		set_default_d_op(sb, &cifs_dentry_ops);
 
 	sb->s_root = d_make_root(inode);
 	if (!sb->s_root) {

fs/tracefs/inode.c

@@ -480,7 +480,7 @@ static int tracefs_fill_super(struct super_block *sb, struct fs_context *fc)
 		return err;
 
 	sb->s_op = &tracefs_super_operations;
-	sb->s_d_op = &tracefs_dentry_operations;
+	set_default_d_op(sb, &tracefs_dentry_operations);
 
 	return 0;
 }

fs/vboxsf/super.c

@@ -189,7 +189,7 @@ static int vboxsf_fill_super(struct super_block *sb, struct fs_context *fc)
 	sb->s_blocksize = 1024;
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	sb->s_op = &vboxsf_super_ops;
-	sb->s_d_op = &vboxsf_dentry_ops;
+	set_default_d_op(sb, &vboxsf_dentry_ops);
 
 	iroot = iget_locked(sb, 0);
 	if (!iroot) {

include/linux/dcache.h

@@ -607,4 +607,6 @@ static inline struct dentry *d_next_sibling(const struct dentry *dentry)
 	return hlist_entry_safe(dentry->d_sib.next, struct dentry, d_sib);
 }
 
+void set_default_d_op(struct super_block *, const struct dentry_operations *);
+
 #endif	/* __LINUX_DCACHE_H */

include/linux/fs.h

@@ -1413,7 +1413,7 @@ struct super_block {
 	 */
 	const char *s_subtype;
 
-	const struct dentry_operations *s_d_op; /* default d_op for dentries */
+	const struct dentry_operations *__s_d_op; /* default d_op for dentries */
 
 	struct shrinker *s_shrink;	/* per-sb shrinker handle */
 

mm/shmem.c

@@ -5028,7 +5028,7 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
 
 	if (ctx->encoding) {
 		sb->s_encoding = ctx->encoding;
-		sb->s_d_op = &shmem_ci_dentry_ops;
+		set_default_d_op(sb, &shmem_ci_dentry_ops);
 		if (ctx->strict_encoding)
 			sb->s_encoding_flags = SB_ENC_STRICT_MODE_FL;
 	}

net/sunrpc/rpc_pipe.c

@@ -1363,7 +1363,7 @@ rpc_fill_super(struct super_block *sb, struct fs_context *fc)
 	sb->s_blocksize_bits = PAGE_SHIFT;
 	sb->s_magic = RPCAUTH_GSSMAGIC;
 	sb->s_op = &s_ops;
-	sb->s_d_op = &simple_dentry_operations;
+	set_default_d_op(sb, &simple_dentry_operations);
 	sb->s_time_gran = 1;
 
 	inode = rpc_get_inode(sb, S_IFDIR | 0555);