fs: port vfs{g,u}id helpers to mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("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 <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

11 files changed, 60 insertions, 81 deletions

diff --git a/fs/attr.c b/fs/attr.c
index a627ac74c4b1..1a100d392dd9 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -379,7 +379,6 @@ EXPORT_SYMBOL(may_setattr);
 int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
 		  struct iattr *attr, struct inode **delegated_inode)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct inode *inode = dentry->d_inode;
 	umode_t mode = inode->i_mode;
 	int error;
@@ -453,11 +452,11 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
 	 * namespace of the superblock.
 	 */
 	if (ia_valid & ATTR_UID &&
-	    !vfsuid_has_fsmapping(mnt_userns, inode->i_sb->s_user_ns,
+	    !vfsuid_has_fsmapping(idmap, inode->i_sb->s_user_ns,
 				  attr->ia_vfsuid))
 		return -EOVERFLOW;
 	if (ia_valid & ATTR_GID &&
-	    !vfsgid_has_fsmapping(mnt_userns, inode->i_sb->s_user_ns,
+	    !vfsgid_has_fsmapping(idmap, inode->i_sb->s_user_ns,
 				  attr->ia_vfsgid))
 		return -EOVERFLOW;
 
diff --git a/fs/fat/file.c b/fs/fat/file.c
index b48ad8acd2c5..795a4fad5c40 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -480,7 +480,6 @@ static int fat_allow_set_time(struct mnt_idmap *idmap,
 int fat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		struct iattr *attr)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 	struct inode *inode = d_inode(dentry);
 	unsigned int ia_valid;
@@ -519,10 +518,10 @@ int fat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	}
 
 	if (((attr->ia_valid & ATTR_UID) &&
-	     (!uid_eq(from_vfsuid(mnt_userns, i_user_ns(inode), attr->ia_vfsuid),
+	     (!uid_eq(from_vfsuid(idmap, i_user_ns(inode), attr->ia_vfsuid),
 		      sbi->options.fs_uid))) ||
 	    ((attr->ia_valid & ATTR_GID) &&
-	     (!gid_eq(from_vfsgid(mnt_userns, i_user_ns(inode), attr->ia_vfsgid),
+	     (!gid_eq(from_vfsgid(idmap, i_user_ns(inode), attr->ia_vfsgid),
 		      sbi->options.fs_gid))) ||
 	    ((attr->ia_valid & ATTR_MODE) &&
 	     (attr->ia_mode & ~FAT_VALID_MODE)))
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 2d182aa31364..795984333bcb 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -2513,7 +2513,6 @@ int smb2_open(struct ksmbd_work *work)
 	struct ksmbd_file *fp = NULL;
 	struct file *filp = NULL;
 	struct mnt_idmap *idmap = NULL;
-	struct user_namespace *user_ns = NULL;
 	struct kstat stat;
 	struct create_context *context;
 	struct lease_ctx_info *lc = NULL;
@@ -2767,7 +2766,6 @@ int smb2_open(struct ksmbd_work *work)
 	} else {
 		file_present = true;
 		idmap = mnt_idmap(path.mnt);
-		user_ns = mnt_idmap_owner(idmap);
 	}
 	if (stream_name) {
 		if (req->CreateOptions & FILE_DIRECTORY_FILE_LE) {
@@ -2867,7 +2865,6 @@ int smb2_open(struct ksmbd_work *work)
 
 		created = true;
 		idmap = mnt_idmap(path.mnt);
-		user_ns = mnt_idmap_owner(idmap);
 		if (ea_buf) {
 			if (le32_to_cpu(ea_buf->ccontext.DataLength) <
 			    sizeof(struct smb2_ea_info)) {
@@ -2999,7 +2996,7 @@ int smb2_open(struct ksmbd_work *work)
 					if (!pntsd)
 						goto err_out;
 
-					rc = build_sec_desc(user_ns,
+					rc = build_sec_desc(idmap,
 							    pntsd, NULL, 0,
 							    OWNER_SECINFO |
 							    GROUP_SECINFO |
@@ -5128,7 +5125,6 @@ static int smb2_get_info_sec(struct ksmbd_work *work,
 {
 	struct ksmbd_file *fp;
 	struct mnt_idmap *idmap;
-	struct user_namespace *user_ns;
 	struct smb_ntsd *pntsd = (struct smb_ntsd *)rsp->Buffer, *ppntsd = NULL;
 	struct smb_fattr fattr = {{0}};
 	struct inode *inode;
@@ -5176,7 +5172,6 @@ static int smb2_get_info_sec(struct ksmbd_work *work,
 		return -ENOENT;
 
 	idmap = file_mnt_idmap(fp->filp);
-	user_ns = mnt_idmap_owner(idmap);
 	inode = file_inode(fp->filp);
 	ksmbd_acls_fattr(&fattr, idmap, inode);
 
@@ -5188,7 +5183,7 @@ static int smb2_get_info_sec(struct ksmbd_work *work,
 
 	/* Check if sd buffer size exceeds response buffer size */
 	if (smb2_resp_buf_len(work, 8) > ppntsd_size)
-		rc = build_sec_desc(user_ns, pntsd, ppntsd, ppntsd_size,
+		rc = build_sec_desc(idmap, pntsd, ppntsd, ppntsd_size,
 				    addition_info, &secdesclen, &fattr);
 	posix_acl_release(fattr.cf_acls);
 	posix_acl_release(fattr.cf_dacls);
diff --git a/fs/ksmbd/smbacl.c b/fs/ksmbd/smbacl.c
index 31255290b435..6d6cfb6957a9 100644
--- a/fs/ksmbd/smbacl.c
+++ b/fs/ksmbd/smbacl.c
@@ -254,7 +254,7 @@ void id_to_sid(unsigned int cid, uint sidtype, struct smb_sid *ssid)
 	ssid->num_subauth++;
 }
 
-static int sid_to_id(struct user_namespace *user_ns,
+static int sid_to_id(struct mnt_idmap *idmap,
 		     struct smb_sid *psid, uint sidtype,
 		     struct smb_fattr *fattr)
 {
@@ -276,7 +276,7 @@ static int sid_to_id(struct user_namespace *user_ns,
 
 		id = le32_to_cpu(psid->sub_auth[psid->num_subauth - 1]);
 		uid = KUIDT_INIT(id);
-		uid = from_vfsuid(user_ns, &init_user_ns, VFSUIDT_INIT(uid));
+		uid = from_vfsuid(idmap, &init_user_ns, VFSUIDT_INIT(uid));
 		if (uid_valid(uid)) {
 			fattr->cf_uid = uid;
 			rc = 0;
@@ -287,7 +287,7 @@ static int sid_to_id(struct user_namespace *user_ns,
 
 		id = le32_to_cpu(psid->sub_auth[psid->num_subauth - 1]);
 		gid = KGIDT_INIT(id);
-		gid = from_vfsgid(user_ns, &init_user_ns, VFSGIDT_INIT(gid));
+		gid = from_vfsgid(idmap, &init_user_ns, VFSGIDT_INIT(gid));
 		if (gid_valid(gid)) {
 			fattr->cf_gid = gid;
 			rc = 0;
@@ -362,7 +362,7 @@ void free_acl_state(struct posix_acl_state *state)
 	kfree(state->groups);
 }
 
-static void parse_dacl(struct user_namespace *user_ns,
+static void parse_dacl(struct mnt_idmap *idmap,
 		       struct smb_acl *pdacl, char *end_of_acl,
 		       struct smb_sid *pownersid, struct smb_sid *pgrpsid,
 		       struct smb_fattr *fattr)
@@ -489,7 +489,7 @@ static void parse_dacl(struct user_namespace *user_ns,
 			acl_mode = access_flags_to_mode(fattr, ppace[i]->access_req,
 							ppace[i]->type);
 			temp_fattr.cf_uid = INVALID_UID;
-			ret = sid_to_id(user_ns, &ppace[i]->sid, SIDOWNER, &temp_fattr);
+			ret = sid_to_id(idmap, &ppace[i]->sid, SIDOWNER, &temp_fattr);
 			if (ret || uid_eq(temp_fattr.cf_uid, INVALID_UID)) {
 				pr_err("%s: Error %d mapping Owner SID to uid\n",
 				       __func__, ret);
@@ -575,7 +575,7 @@ static void parse_dacl(struct user_namespace *user_ns,
 	free_acl_state(&default_acl_state);
 }
 
-static void set_posix_acl_entries_dacl(struct user_namespace *user_ns,
+static void set_posix_acl_entries_dacl(struct mnt_idmap *idmap,
 				       struct smb_ace *pndace,
 				       struct smb_fattr *fattr, u32 *num_aces,
 				       u16 *size, u32 nt_aces_num)
@@ -600,14 +600,14 @@ static void set_posix_acl_entries_dacl(struct user_namespace *user_ns,
 			uid_t uid;
 			unsigned int sid_type = SIDOWNER;
 
-			uid = posix_acl_uid_translate(user_ns, pace);
+			uid = posix_acl_uid_translate(idmap, pace);
 			if (!uid)
 				sid_type = SIDUNIX_USER;
 			id_to_sid(uid, sid_type, sid);
 		} else if (pace->e_tag == ACL_GROUP) {
 			gid_t gid;
 
-			gid = posix_acl_gid_translate(user_ns, pace);
+			gid = posix_acl_gid_translate(idmap, pace);
 			id_to_sid(gid, SIDUNIX_GROUP, sid);
 		} else if (pace->e_tag == ACL_OTHER && !nt_aces_num) {
 			smb_copy_sid(sid, &sid_everyone);
@@ -666,12 +666,12 @@ posix_default_acl:
 		if (pace->e_tag == ACL_USER) {
 			uid_t uid;
 
-			uid = posix_acl_uid_translate(user_ns, pace);
+			uid = posix_acl_uid_translate(idmap, pace);
 			id_to_sid(uid, SIDCREATOR_OWNER, sid);
 		} else if (pace->e_tag == ACL_GROUP) {
 			gid_t gid;
 
-			gid = posix_acl_gid_translate(user_ns, pace);
+			gid = posix_acl_gid_translate(idmap, pace);
 			id_to_sid(gid, SIDCREATOR_GROUP, sid);
 		} else {
 			kfree(sid);
@@ -689,7 +689,7 @@ posix_default_acl:
 	}
 }
 
-static void set_ntacl_dacl(struct user_namespace *user_ns,
+static void set_ntacl_dacl(struct mnt_idmap *idmap,
 			   struct smb_acl *pndacl,
 			   struct smb_acl *nt_dacl,
 			   unsigned int aces_size,
@@ -723,13 +723,13 @@ static void set_ntacl_dacl(struct user_namespace *user_ns,
 		}
 	}
 
-	set_posix_acl_entries_dacl(user_ns, pndace, fattr,
+	set_posix_acl_entries_dacl(idmap, pndace, fattr,
 				   &num_aces, &size, nt_num_aces);
 	pndacl->num_aces = cpu_to_le32(num_aces);
 	pndacl->size = cpu_to_le16(le16_to_cpu(pndacl->size) + size);
 }
 
-static void set_mode_dacl(struct user_namespace *user_ns,
+static void set_mode_dacl(struct mnt_idmap *idmap,
 			  struct smb_acl *pndacl, struct smb_fattr *fattr)
 {
 	struct smb_ace *pace, *pndace;
@@ -741,7 +741,7 @@ static void set_mode_dacl(struct user_namespace *user_ns,
 	pace = pndace = (struct smb_ace *)((char *)pndacl + sizeof(struct smb_acl));
 
 	if (fattr->cf_acls) {
-		set_posix_acl_entries_dacl(user_ns, pndace, fattr,
+		set_posix_acl_entries_dacl(idmap, pndace, fattr,
 					   &num_aces, &size, num_aces);
 		goto out;
 	}
@@ -808,7 +808,7 @@ static int parse_sid(struct smb_sid *psid, char *end_of_acl)
 }
 
 /* Convert CIFS ACL to POSIX form */
-int parse_sec_desc(struct user_namespace *user_ns, struct smb_ntsd *pntsd,
+int parse_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
 		   int acl_len, struct smb_fattr *fattr)
 {
 	int rc = 0;
@@ -851,7 +851,7 @@ int parse_sec_desc(struct user_namespace *user_ns, struct smb_ntsd *pntsd,
 			return rc;
 		}
 
-		rc = sid_to_id(user_ns, owner_sid_ptr, SIDOWNER, fattr);
+		rc = sid_to_id(idmap, owner_sid_ptr, SIDOWNER, fattr);
 		if (rc) {
 			pr_err("%s: Error %d mapping Owner SID to uid\n",
 			       __func__, rc);
@@ -866,7 +866,7 @@ int parse_sec_desc(struct user_namespace *user_ns, struct smb_ntsd *pntsd,
 			       __func__, rc);
 			return rc;
 		}
-		rc = sid_to_id(user_ns, group_sid_ptr, SIDUNIX_GROUP, fattr);
+		rc = sid_to_id(idmap, group_sid_ptr, SIDUNIX_GROUP, fattr);
 		if (rc) {
 			pr_err("%s: Error %d mapping Group SID to gid\n",
 			       __func__, rc);
@@ -881,7 +881,7 @@ int parse_sec_desc(struct user_namespace *user_ns, struct smb_ntsd *pntsd,
 		pntsd->type |= cpu_to_le16(DACL_PROTECTED);
 
 	if (dacloffset) {
-		parse_dacl(user_ns, dacl_ptr, end_of_acl,
+		parse_dacl(idmap, dacl_ptr, end_of_acl,
 			   owner_sid_ptr, group_sid_ptr, fattr);
 	}
 
@@ -889,7 +889,7 @@ int parse_sec_desc(struct user_namespace *user_ns, struct smb_ntsd *pntsd,
 }
 
 /* Convert permission bits from mode to equivalent CIFS ACL */
-int build_sec_desc(struct user_namespace *user_ns,
+int build_sec_desc(struct mnt_idmap *idmap,
 		   struct smb_ntsd *pntsd, struct smb_ntsd *ppntsd,
 		   int ppntsd_size, int addition_info, __u32 *secdesclen,
 		   struct smb_fattr *fattr)
@@ -950,7 +950,7 @@ int build_sec_desc(struct user_namespace *user_ns,
 		dacl_ptr->num_aces = 0;
 
 		if (!ppntsd) {
-			set_mode_dacl(user_ns, dacl_ptr, fattr);
+			set_mode_dacl(idmap, dacl_ptr, fattr);
 		} else {
 			struct smb_acl *ppdacl_ptr;
 			unsigned int dacl_offset = le32_to_cpu(ppntsd->dacloffset);
@@ -966,7 +966,7 @@ int build_sec_desc(struct user_namespace *user_ns,
 			    ppdacl_size < sizeof(struct smb_acl))
 				goto out;
 
-			set_ntacl_dacl(user_ns, dacl_ptr, ppdacl_ptr,
+			set_ntacl_dacl(idmap, dacl_ptr, ppdacl_ptr,
 				       ntacl_size - sizeof(struct smb_acl),
 				       nowner_sid_ptr, ngroup_sid_ptr,
 				       fattr);
@@ -1191,7 +1191,6 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
 			__le32 *pdaccess, int uid)
 {
 	struct mnt_idmap *idmap = mnt_idmap(path->mnt);
-	struct user_namespace *user_ns = mnt_idmap_owner(idmap);
 	struct smb_ntsd *pntsd = NULL;
 	struct smb_acl *pdacl;
 	struct posix_acl *posix_acls;
@@ -1297,9 +1296,9 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
 			pa_entry = posix_acls->a_entries;
 			for (i = 0; i < posix_acls->a_count; i++, pa_entry++) {
 				if (pa_entry->e_tag == ACL_USER)
-					id = posix_acl_uid_translate(user_ns, pa_entry);
+					id = posix_acl_uid_translate(idmap, pa_entry);
 				else if (pa_entry->e_tag == ACL_GROUP)
-					id = posix_acl_gid_translate(user_ns, pa_entry);
+					id = posix_acl_gid_translate(idmap, pa_entry);
 				else
 					continue;
 
@@ -1362,14 +1361,13 @@ int set_info_sec(struct ksmbd_conn *conn, struct ksmbd_tree_connect *tcon,
 	struct smb_fattr fattr = {{0}};
 	struct inode *inode = d_inode(path->dentry);
 	struct mnt_idmap *idmap = mnt_idmap(path->mnt);
-	struct user_namespace *user_ns = mnt_idmap_owner(idmap);
 	struct iattr newattrs;
 
 	fattr.cf_uid = INVALID_UID;
 	fattr.cf_gid = INVALID_GID;
 	fattr.cf_mode = inode->i_mode;
 
-	rc = parse_sec_desc(user_ns, pntsd, ntsd_len, &fattr);
+	rc = parse_sec_desc(idmap, pntsd, ntsd_len, &fattr);
 	if (rc)
 		goto out;
 
diff --git a/fs/ksmbd/smbacl.h b/fs/ksmbd/smbacl.h
index 618f2e0236b3..49a8c292bd2e 100644
--- a/fs/ksmbd/smbacl.h
+++ b/fs/ksmbd/smbacl.h
@@ -190,9 +190,9 @@ struct posix_acl_state {
 	struct posix_ace_state_array *groups;
 };
 
-int parse_sec_desc(struct user_namespace *user_ns, struct smb_ntsd *pntsd,
+int parse_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
 		   int acl_len, struct smb_fattr *fattr);
-int build_sec_desc(struct user_namespace *user_ns, struct smb_ntsd *pntsd,
+int build_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
 		   struct smb_ntsd *ppntsd, int ppntsd_size, int addition_info,
 		   __u32 *secdesclen, struct smb_fattr *fattr);
 int init_acl_state(struct posix_acl_state *state, int cnt);
@@ -211,25 +211,25 @@ int set_info_sec(struct ksmbd_conn *conn, struct ksmbd_tree_connect *tcon,
 void id_to_sid(unsigned int cid, uint sidtype, struct smb_sid *ssid);
 void ksmbd_init_domain(u32 *sub_auth);
 
-static inline uid_t posix_acl_uid_translate(struct user_namespace *mnt_userns,
+static inline uid_t posix_acl_uid_translate(struct mnt_idmap *idmap,
 					    struct posix_acl_entry *pace)
 {
 	vfsuid_t vfsuid;
 
 	/* If this is an idmapped mount, apply the idmapping. */
-	vfsuid = make_vfsuid(mnt_userns, &init_user_ns, pace->e_uid);
+	vfsuid = make_vfsuid(idmap, &init_user_ns, pace->e_uid);
 
 	/* Translate the kuid into a userspace id ksmbd would see. */
 	return from_kuid(&init_user_ns, vfsuid_into_kuid(vfsuid));
 }
 
-static inline gid_t posix_acl_gid_translate(struct user_namespace *mnt_userns,
+static inline gid_t posix_acl_gid_translate(struct mnt_idmap *idmap,
 					    struct posix_acl_entry *pace)
 {
 	vfsgid_t vfsgid;
 
 	/* If this is an idmapped mount, apply the idmapping. */
-	vfsgid = make_vfsgid(mnt_userns, &init_user_ns, pace->e_gid);
+	vfsgid = make_vfsgid(idmap, &init_user_ns, pace->e_gid);
 
 	/* Translate the kgid into a userspace id ksmbd would see. */
 	return from_kgid(&init_user_ns, vfsgid_into_kgid(vfsgid));
diff --git a/fs/ksmbd/vfs.c b/fs/ksmbd/vfs.c
index a1b3e4ef8045..fb699a62e68e 100644
--- a/fs/ksmbd/vfs.c
+++ b/fs/ksmbd/vfs.c
@@ -1362,7 +1362,7 @@ out:
 	return err;
 }
 
-static struct xattr_smb_acl *ksmbd_vfs_make_xattr_posix_acl(struct user_namespace *user_ns,
+static struct xattr_smb_acl *ksmbd_vfs_make_xattr_posix_acl(struct mnt_idmap *idmap,
 							    struct inode *inode,
 							    int acl_type)
 {
@@ -1392,14 +1392,14 @@ static struct xattr_smb_acl *ksmbd_vfs_make_xattr_posix_acl(struct user_namespac
 		switch (pa_entry->e_tag) {
 		case ACL_USER:
 			xa_entry->type = SMB_ACL_USER;
-			xa_entry->uid = posix_acl_uid_translate(user_ns, pa_entry);
+			xa_entry->uid = posix_acl_uid_translate(idmap, pa_entry);
 			break;
 		case ACL_USER_OBJ:
 			xa_entry->type = SMB_ACL_USER_OBJ;
 			break;
 		case ACL_GROUP:
 			xa_entry->type = SMB_ACL_GROUP;
-			xa_entry->gid = posix_acl_gid_translate(user_ns, pa_entry);
+			xa_entry->gid = posix_acl_gid_translate(idmap, pa_entry);
 			break;
 		case ACL_GROUP_OBJ:
 			xa_entry->type = SMB_ACL_GROUP_OBJ;
@@ -1433,7 +1433,6 @@ int ksmbd_vfs_set_sd_xattr(struct ksmbd_conn *conn,
 			   struct smb_ntsd *pntsd, int len)
 {
 	int rc;
-	struct user_namespace *user_ns = mnt_idmap_owner(idmap);
 	struct ndr sd_ndr = {0}, acl_ndr = {0};
 	struct xattr_ntacl acl = {0};
 	struct xattr_smb_acl *smb_acl, *def_smb_acl = NULL;
@@ -1462,10 +1461,10 @@ int ksmbd_vfs_set_sd_xattr(struct ksmbd_conn *conn,
 		return rc;
 	}
 
-	smb_acl = ksmbd_vfs_make_xattr_posix_acl(user_ns, inode,
+	smb_acl = ksmbd_vfs_make_xattr_posix_acl(idmap, inode,
 						 ACL_TYPE_ACCESS);
 	if (S_ISDIR(inode->i_mode))
-		def_smb_acl = ksmbd_vfs_make_xattr_posix_acl(user_ns, inode,
+		def_smb_acl = ksmbd_vfs_make_xattr_posix_acl(idmap, inode,
 							     ACL_TYPE_DEFAULT);
 
 	rc = ndr_encode_posix_acl(&acl_ndr, idmap, inode,
@@ -1508,7 +1507,6 @@ int ksmbd_vfs_get_sd_xattr(struct ksmbd_conn *conn,
 			   struct smb_ntsd **pntsd)
 {
 	int rc;
-	struct user_namespace *user_ns = mnt_idmap_owner(idmap);
 	struct ndr n;
 	struct inode *inode = d_inode(dentry);
 	struct ndr acl_ndr = {0};
@@ -1525,10 +1523,10 @@ int ksmbd_vfs_get_sd_xattr(struct ksmbd_conn *conn,
 	if (rc)
 		goto free_n_data;
 
-	smb_acl = ksmbd_vfs_make_xattr_posix_acl(user_ns, inode,
+	smb_acl = ksmbd_vfs_make_xattr_posix_acl(idmap, inode,
 						 ACL_TYPE_ACCESS);
 	if (S_ISDIR(inode->i_mode))
-		def_smb_acl = ksmbd_vfs_make_xattr_posix_acl(user_ns, inode,
+		def_smb_acl = ksmbd_vfs_make_xattr_posix_acl(idmap, inode,
 							     ACL_TYPE_DEFAULT);
 
 	rc = ndr_encode_posix_acl(&acl_ndr, idmap, inode, smb_acl,
diff --git a/fs/open.c b/fs/open.c
index e9e5da4815a9..f9d48da3c630 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -702,7 +702,7 @@ static inline bool setattr_vfsgid(struct iattr *attr, kgid_t kgid)
 int chown_common(const struct path *path, uid_t user, gid_t group)
 {
 	struct mnt_idmap *idmap;
-	struct user_namespace *mnt_userns, *fs_userns;
+	struct user_namespace *fs_userns;
 	struct inode *inode = path->dentry->d_inode;
 	struct inode *delegated_inode = NULL;
 	int error;
@@ -714,7 +714,6 @@ int chown_common(const struct path *path, uid_t user, gid_t group)
 	gid = make_kgid(current_user_ns(), group);
 
 	idmap = mnt_idmap(path->mnt);
-	mnt_userns = mnt_idmap_owner(idmap);
 	fs_userns = i_user_ns(inode);
 
 retry_deleg:
@@ -732,8 +731,8 @@ retry_deleg:
 	/* Continue to send actual fs values, not the mount values. */
 	error = security_path_chown(
 		path,
-		from_vfsuid(mnt_userns, fs_userns, newattrs.ia_vfsuid),
-		from_vfsgid(mnt_userns, fs_userns, newattrs.ia_vfsgid));
+		from_vfsuid(idmap, fs_userns, newattrs.ia_vfsuid),
+		from_vfsgid(idmap, fs_userns, newattrs.ia_vfsgid));
 	if (!error)
 		error = notify_change(idmap, path->dentry, &newattrs,
 				      &delegated_inode);
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 4e56d0cb7cce..541cf3717fc2 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -463,7 +463,7 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
  * alter the POSIX ACLs for the underlying filesystem.
  */
 static void ovl_idmap_posix_acl(const struct inode *realinode,
-				struct user_namespace *mnt_userns,
+				struct mnt_idmap *idmap,
 				struct posix_acl *acl)
 {
 	struct user_namespace *fs_userns = i_user_ns(realinode);
@@ -475,11 +475,11 @@ static void ovl_idmap_posix_acl(const struct inode *realinode,
 		struct posix_acl_entry *e = &acl->a_entries[i];
 		switch (e->e_tag) {
 		case ACL_USER:
-			vfsuid = make_vfsuid(mnt_userns, fs_userns, e->e_uid);
+			vfsuid = make_vfsuid(idmap, fs_userns, e->e_uid);
 			e->e_uid = vfsuid_into_kuid(vfsuid);
 			break;
 		case ACL_GROUP:
-			vfsgid = make_vfsgid(mnt_userns, fs_userns, e->e_gid);
+			vfsgid = make_vfsgid(idmap, fs_userns, e->e_gid);
 			e->e_gid = vfsgid_into_kgid(vfsgid);
 			break;
 		}
@@ -514,12 +514,10 @@ struct posix_acl *ovl_get_acl_path(const struct path *path,
 				   const char *acl_name, bool noperm)
 {
 	struct posix_acl *real_acl, *clone;
-	struct user_namespace *mnt_userns;
 	struct mnt_idmap *idmap;
 	struct inode *realinode = d_inode(path->dentry);
 
 	idmap = mnt_idmap(path->mnt);
-	mnt_userns = mnt_idmap_owner(idmap);
 
 	if (noperm)
 		real_acl = get_inode_acl(realinode, posix_acl_type(acl_name));
@@ -542,7 +540,7 @@ struct posix_acl *ovl_get_acl_path(const struct path *path,
 	if (!clone)
 		return ERR_PTR(-ENOMEM);
 
-	ovl_idmap_posix_acl(realinode, mnt_userns, clone);
+	ovl_idmap_posix_acl(realinode, idmap, clone);
 	return clone;
 }
 
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 7e0a8a068f98..8cc52110f1f9 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -377,7 +377,6 @@ posix_acl_permission(struct mnt_idmap *idmap, struct inode *inode,
 {
 	const struct posix_acl_entry *pa, *pe, *mask_obj;
 	struct user_namespace *fs_userns = i_user_ns(inode);
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	int found = 0;
 	vfsuid_t vfsuid;
 	vfsgid_t vfsgid;
@@ -393,7 +392,7 @@ posix_acl_permission(struct mnt_idmap *idmap, struct inode *inode,
                                         goto check_perm;
                                 break;
                         case ACL_USER:
-				vfsuid = make_vfsuid(mnt_userns, fs_userns,
+				vfsuid = make_vfsuid(idmap, fs_userns,
 						     pa->e_uid);
 				if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
                                         goto mask;
@@ -407,7 +406,7 @@ posix_acl_permission(struct mnt_idmap *idmap, struct inode *inode,
                                 }
 				break;
                         case ACL_GROUP:
-				vfsgid = make_vfsgid(mnt_userns, fs_userns,
+				vfsgid = make_vfsgid(idmap, fs_userns,
 						     pa->e_gid);
 				if (vfsgid_in_group_p(vfsgid)) {
 					found = 1;
@@ -894,7 +893,6 @@ static ssize_t vfs_posix_acl_to_xattr(struct mnt_idmap *idmap,
 	struct posix_acl_xattr_header *ext_acl = buffer;
 	struct posix_acl_xattr_entry *ext_entry;
 	struct user_namespace *fs_userns, *caller_userns;
-	struct user_namespace *mnt_userns;
 	ssize_t real_size, n;
 	vfsuid_t vfsuid;
 	vfsgid_t vfsgid;
@@ -910,19 +908,18 @@ static ssize_t vfs_posix_acl_to_xattr(struct mnt_idmap *idmap,
 
 	fs_userns = i_user_ns(inode);
 	caller_userns = current_user_ns();
-	mnt_userns = mnt_idmap_owner(idmap);
 	for (n=0; n < acl->a_count; n++, ext_entry++) {
 		const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 		ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 		ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
 		switch(acl_e->e_tag) {
 		case ACL_USER:
-			vfsuid = make_vfsuid(mnt_userns, fs_userns, acl_e->e_uid);
+			vfsuid = make_vfsuid(idmap, fs_userns, acl_e->e_uid);
 			ext_entry->e_id = cpu_to_le32(from_kuid(
 				caller_userns, vfsuid_into_kuid(vfsuid)));
 			break;
 		case ACL_GROUP:
-			vfsgid = make_vfsgid(mnt_userns, fs_userns, acl_e->e_gid);
+			vfsgid = make_vfsgid(idmap, fs_userns, acl_e->e_gid);
 			ext_entry->e_id = cpu_to_le32(from_kgid(
 				caller_userns, vfsgid_into_kgid(vfsgid)));
 			break;
@@ -1022,18 +1019,16 @@ static int vfs_set_acl_idmapped_mnt(struct mnt_idmap *idmap,
 				    struct user_namespace *fs_userns,
 				    struct posix_acl *acl)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
-
 	for (int n = 0; n < acl->a_count; n++) {
 		struct posix_acl_entry *acl_e = &acl->a_entries[n];
 
 		switch (acl_e->e_tag) {
 		case ACL_USER:
-			acl_e->e_uid = from_vfsuid(mnt_userns, fs_userns,
+			acl_e->e_uid = from_vfsuid(idmap, fs_userns,
 						   VFSUIDT_INIT(acl_e->e_uid));
 			break;
 		case ACL_GROUP:
-			acl_e->e_gid = from_vfsgid(mnt_userns, fs_userns,
+			acl_e->e_gid = from_vfsgid(idmap, fs_userns,
 						   VFSGIDT_INIT(acl_e->e_gid));
 			break;
 		}
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 207434a854f3..a6357f728034 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2088,7 +2088,6 @@ EXPORT_SYMBOL(__dquot_transfer);
 int dquot_transfer(struct mnt_idmap *idmap, struct inode *inode,
 		   struct iattr *iattr)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct dquot *transfer_to[MAXQUOTAS] = {};
 	struct dquot *dquot;
 	struct super_block *sb = inode->i_sb;
@@ -2098,7 +2097,7 @@ int dquot_transfer(struct mnt_idmap *idmap, struct inode *inode,
 		return 0;
 
 	if (i_uid_needs_update(idmap, iattr, inode)) {
-		kuid_t kuid = from_vfsuid(mnt_userns, i_user_ns(inode),
+		kuid_t kuid = from_vfsuid(idmap, i_user_ns(inode),
 					  iattr->ia_vfsuid);
 
 		dquot = dqget(sb, make_kqid_uid(kuid));
@@ -2112,7 +2111,7 @@ int dquot_transfer(struct mnt_idmap *idmap, struct inode *inode,
 		transfer_to[USRQUOTA] = dquot;
 	}
 	if (i_gid_needs_update(idmap, iattr, inode)) {
-		kgid_t kgid = from_vfsgid(mnt_userns, i_user_ns(inode),
+		kgid_t kgid = from_vfsgid(idmap, i_user_ns(inode),
 					  iattr->ia_vfsgid);
 
 		dquot = dqget(sb, make_kqid_gid(kgid));
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index d54423311831..24718adb3c16 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -663,7 +663,6 @@ xfs_setattr_nonsize(
 	kgid_t			gid = GLOBAL_ROOT_GID;
 	struct xfs_dquot	*udqp = NULL, *gdqp = NULL;
 	struct xfs_dquot	*old_udqp = NULL, *old_gdqp = NULL;
-	struct user_namespace	*mnt_userns = mnt_idmap_owner(idmap);
 
 	ASSERT((mask & ATTR_SIZE) == 0);
 
@@ -679,14 +678,14 @@ xfs_setattr_nonsize(
 		uint	qflags = 0;
 
 		if ((mask & ATTR_UID) && XFS_IS_UQUOTA_ON(mp)) {
-			uid = from_vfsuid(mnt_userns, i_user_ns(inode),
+			uid = from_vfsuid(idmap, i_user_ns(inode),
 					  iattr->ia_vfsuid);
 			qflags |= XFS_QMOPT_UQUOTA;
 		} else {
 			uid = inode->i_uid;
 		}
 		if ((mask & ATTR_GID) && XFS_IS_GQUOTA_ON(mp)) {
-			gid = from_vfsgid(mnt_userns, i_user_ns(inode),
+			gid = from_vfsgid(idmap, i_user_ns(inode),
 					  iattr->ia_vfsgid);
 			qflags |= XFS_QMOPT_GQUOTA;
 		}  else {