linux-kernel - [PATCH v6 4/6] fs: make vfs_fileattr

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Message-Id: <20250630-xattrat-syscall-v6-4-c4e3bc35227b@kernel.org>
Date: Mon, 30 Jun 2025 18:20:14 +0200
From: Andrey Albershteyn <aalbersh@...hat.com>
To: Amir Goldstein <amir73il@...il.com>, Arnd Bergmann <arnd@...db.de>, 
 Casey Schaufler <casey@...aufler-ca.com>, 
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
 Pali Rohár <pali@...nel.org>, 
 Paul Moore <paul@...l-moore.com>
Cc: linux-api@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org, 
 selinux@...r.kernel.org, Andrey Albershteyn <aalbersh@...nel.org>
Subject: [PATCH v6 4/6] fs: make vfs_fileattr_[get|set] return -EOPNOSUPP

Future patches will add new syscalls which use these functions. As
this interface won't be used for ioctls only, the EOPNOSUPP is more
appropriate return code.

This patch converts return code from ENOIOCTLCMD to EOPNOSUPP for
vfs_fileattr_get and vfs_fileattr_set. To save old behavior translate
EOPNOSUPP back for current users - overlayfs, encryptfs and fs/ioctl.c.

Signed-off-by: Andrey Albershteyn <aalbersh@...nel.org>
---
 fs/ecryptfs/inode.c  |  8 +++++++-
 fs/file_attr.c       | 12 ++++++++++--
 fs/overlayfs/inode.c |  2 +-
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 493d7f194956..a55c1375127f 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -1126,7 +1126,13 @@ static int ecryptfs_removexattr(struct dentry *dentry, struct inode *inode,
 
 static int ecryptfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 {
-	return vfs_fileattr_get(ecryptfs_dentry_to_lower(dentry), fa);
+	int rc;
+
+	rc = vfs_fileattr_get(ecryptfs_dentry_to_lower(dentry), fa);
+	if (rc == -EOPNOTSUPP)
+		rc = -ENOIOCTLCMD;
+
+	return rc;
 }
 
 static int ecryptfs_fileattr_set(struct mnt_idmap *idmap,
diff --git a/fs/file_attr.c b/fs/file_attr.c
index be62d97cc444..4e85fa00c092 100644
--- a/fs/file_attr.c
+++ b/fs/file_attr.c
@@ -79,7 +79,7 @@ int vfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 	int error;
 
 	if (!inode->i_op->fileattr_get)
-		return -ENOIOCTLCMD;
+		return -EOPNOTSUPP;
 
 	error = security_inode_file_getattr(dentry, fa);
 	if (error)
@@ -229,7 +229,7 @@ int vfs_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry,
 	int err;
 
 	if (!inode->i_op->fileattr_set)
-		return -ENOIOCTLCMD;
+		return -EOPNOTSUPP;
 
 	if (!inode_owner_or_capable(idmap, inode))
 		return -EPERM;
@@ -271,6 +271,8 @@ int ioctl_getflags(struct file *file, unsigned int __user *argp)
 	int err;
 
 	err = vfs_fileattr_get(file->f_path.dentry, &fa);
+	if (err == -EOPNOTSUPP)
+		err = -ENOIOCTLCMD;
 	if (!err)
 		err = put_user(fa.flags, argp);
 	return err;
@@ -292,6 +294,8 @@ int ioctl_setflags(struct file *file, unsigned int __user *argp)
 			fileattr_fill_flags(&fa, flags);
 			err = vfs_fileattr_set(idmap, dentry, &fa);
 			mnt_drop_write_file(file);
+			if (err == -EOPNOTSUPP)
+				err = -ENOIOCTLCMD;
 		}
 	}
 	return err;
@@ -304,6 +308,8 @@ int ioctl_fsgetxattr(struct file *file, void __user *argp)
 	int err;
 
 	err = vfs_fileattr_get(file->f_path.dentry, &fa);
+	if (err == -EOPNOTSUPP)
+		err = -ENOIOCTLCMD;
 	if (!err)
 		err = copy_fsxattr_to_user(&fa, argp);
 
@@ -324,6 +330,8 @@ int ioctl_fssetxattr(struct file *file, void __user *argp)
 		if (!err) {
 			err = vfs_fileattr_set(idmap, dentry, &fa);
 			mnt_drop_write_file(file);
+			if (err == -EOPNOTSUPP)
+				err = -ENOIOCTLCMD;
 		}
 	}
 	return err;
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 6f0e15f86c21..096d44712bb1 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -721,7 +721,7 @@ int ovl_real_fileattr_get(const struct path *realpath, struct fileattr *fa)
 		return err;
 
 	err = vfs_fileattr_get(realpath->dentry, fa);
-	if (err == -ENOIOCTLCMD)
+	if (err == -EOPNOTSUPP)
 		err = -ENOTTY;
 	return err;
 }

-- 
2.47.2