From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1276A318BB8; Sun, 31 May 2026 14:08:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780236531; cv=none; b=RPDaOvi6sZ9cTbD5ZwT5+ZzlcOCYfVK99HQjQMPgU8c36LUZzZwFAOw8uK5tg2uIgtiomsY9c1rnZH8u7FUbOf4WhEZp5wowHBKWdyFDqoGgDBa+P/BalT8C0U6zhe57ZTL5PsVehsuMt1kBl0zjO6XEibkTQvIkBa7pOe/g/nA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780236531; c=relaxed/simple; bh=jyVPKZ0/cmUu98r1EWJCouBj7DMt2S6yi2wrVOlOqxc=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=eTx5k5siKx50TUlPzYrIZgqu2pY9qaKEpbjxAmxUyVMRn9tHJ38mp1xjOxWwfUFSxXd4srxpK6zSRdnTVUz7NbPMBSTknrJ0CDgbY3uw6ozatSW6azV308faF6bKPQ0oy+KOiWkpoL12yOnXsKtablHMd0/Fnl5UDaZYOt8lVK0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dL5LJs3w; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dL5LJs3w" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6AEB1F0089A; Sun, 31 May 2026 14:08:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780236529; bh=INFoxaNJI2f4ewr1YrT0YJcK+/YNafUWsGD89A8ln2A=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=dL5LJs3w/ON5xLUnEVICW76EXbA1u/PyGoanlYw2ohdTe1D1ckIcWw1KIBhyFheNX 5TK4pDWjqWPdMs7qQGC3wuLbcaWXXsxR3kkLcoeuE4GHA6eFVrVbf2ks3gVcIa1VMF 4S/G3FLc1WAjqSKhkF2XSvnSGHsQvVlRQ3y9fYGRSkRt6QvVGE+9BOLllQVmJStYjH gPPg/BiC+v12n3RggfZmbVkYkmaBjmCBKQgNr+9i7FS1CAPqd6PieCLvjL2+8AgeDz EdwxZTJPAdHx+8Kjhh8dS9J7DDm+XmnPXbElULIyVUbnii2dtj+fP5RGaalHJZmGEQ aE43Pcs769Okw== Message-ID: Subject: Re: [PATCH] vfs: missing inode operation should return a consistent error code From: Jeff Layton To: Jori Koolstra , Alexander Viro , Christian Brauner , Jan Kara , Arnd Bergmann Cc: "open list:FILESYSTEMS (VFS and infrastructure)" , open list , "open list:GENERIC INCLUDE/ASM HEADER FILES" Date: Sun, 31 May 2026 10:08:47 -0400 In-Reply-To: <20260531104947.6142-1-jkoolstra@xs4all.nl> References: <20260531104947.6142-1-jkoolstra@xs4all.nl> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 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different error codes are used in the VFS for > situations where the underlying filesystem does not support the > requested inode operation (such as mkdir, tmpfile, create, etc.) > Examples: create returns EACCES, mkdir EPERM, tmpfile EOPNOTSUPP, > fileattr_get ENOIOCTLCMD. >=20 > We should provide a sensible unified error code for these situations. > EOPNOTSUPP is already used for this both in the kernel (when lacking > tmpfile support) and in userland (e.g. glibc).[1] Restricting EOPNOTSUPP > to socket operations as POSIX suggests is not the current reality and > this was recently changed in the man page as well.[2] >=20 > vfs_fileattr_get|set return ENOIOCTLCMD, but this cannot be changed > since EOPNOTSUPP is already used to by underlying filesystems to indicate > that a flag is not supported. The change to EOPNOTSUPP was reverted by > 4dd5b5ac089b ("Revert "fs: make vfs_fileattr_[get|set] return > -EOPNOTSUPP"") >=20 > [1]: https://lore.kernel.org/all/20260528-abnimmt-befreien-perspektive-a7= 930659fb40@brauner/ > [2]: https://lore.kernel.org/linux-fsdevel/ahd3SmZZqnzP0-O2@devuan/T/#t >=20 > Signed-off-by: Jori Koolstra > --- > fs/namei.c | 18 +++++++++--------- > include/uapi/asm-generic/errno.h | 2 +- > 2 files changed, 10 insertions(+), 10 deletions(-) >=20 > diff --git a/fs/namei.c b/fs/namei.c > index c7fac83c9a85..813419c340ad 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -4192,7 +4192,7 @@ int vfs_create(struct mnt_idmap *idmap, struct dent= ry *dentry, umode_t mode, > return error; > =20 > if (!dir->i_op->create) > - return -EACCES; /* shouldn't it be ENOSYS? */ > + return -EOPNOTSUPP; > =20 > mode =3D vfs_prepare_mode(idmap, dir, mode, S_IALLUGO, S_IFREG); > error =3D security_inode_create(dir, dentry, mode); > @@ -4504,7 +4504,7 @@ static struct dentry *lookup_open(struct nameidata = *nd, struct file *file, > file->f_mode |=3D FMODE_CREATED; > audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); > if (!dir_inode->i_op->create) { > - error =3D -EACCES; > + error =3D -EOPNOTSUPP; > goto out_dput; > } > =20 > @@ -5102,7 +5102,7 @@ int vfs_mknod(struct mnt_idmap *idmap, struct inode= *dir, > return -EPERM; > =20 > if (!dir->i_op->mknod) > - return -EPERM; > + return -EOPNOTSUPP; > =20 > mode =3D vfs_prepare_mode(idmap, dir, mode, mode, mode); > error =3D devcgroup_inode_mknod(mode, dev); > @@ -5241,7 +5241,7 @@ struct dentry *vfs_mkdir(struct mnt_idmap *idmap, s= truct inode *dir, > if (error) > goto err; > =20 > - error =3D -EPERM; > + error =3D -EOPNOTSUPP; > if (!dir->i_op->mkdir) > goto err; > =20 > @@ -5345,7 +5345,7 @@ int vfs_rmdir(struct mnt_idmap *idmap, struct inode= *dir, > return error; > =20 > if (!dir->i_op->rmdir) > - return -EPERM; > + return -EOPNOTSUPP; > =20 > dget(dentry); > inode_lock(dentry->d_inode); > @@ -5479,7 +5479,7 @@ int vfs_unlink(struct mnt_idmap *idmap, struct inod= e *dir, > return error; > =20 > if (!dir->i_op->unlink) > - return -EPERM; > + return -EOPNOTSUPP; > =20 > inode_lock(target); > if (IS_SWAPFILE(target)) > @@ -5630,7 +5630,7 @@ int vfs_symlink(struct mnt_idmap *idmap, struct ino= de *dir, > return error; > =20 > if (!dir->i_op->symlink) > - return -EPERM; > + return -EOPNOTSUPP; > =20 > error =3D security_inode_symlink(dir, dentry, oldname); > if (error) > @@ -5752,7 +5752,7 @@ int vfs_link(struct dentry *old_dentry, struct mnt_= idmap *idmap, > if (HAS_UNMAPPED_ID(idmap, inode)) > return -EPERM; > if (!dir->i_op->link) > - return -EPERM; > + return -EOPNOTSUPP; > if (S_ISDIR(inode->i_mode)) > return -EPERM; > =20 > @@ -5961,7 +5961,7 @@ int vfs_rename(struct renamedata *rd) > return error; > =20 > if (!old_dir->i_op->rename) > - return -EPERM; > + return -EOPNOTSUPP; > =20 > /* > * If we are going to change the parent - check write permissions, > diff --git a/include/uapi/asm-generic/errno.h b/include/uapi/asm-generic/= errno.h > index 92e7ae493ee3..7b5b71ae1b12 100644 > --- a/include/uapi/asm-generic/errno.h > +++ b/include/uapi/asm-generic/errno.h > @@ -76,7 +76,7 @@ > #define ENOPROTOOPT 92 /* Protocol not available */ > #define EPROTONOSUPPORT 93 /* Protocol not supported */ > #define ESOCKTNOSUPPORT 94 /* Socket type not supported */ > -#define EOPNOTSUPP 95 /* Operation not supported on transport endpoint *= / > +#define EOPNOTSUPP 95 /* Operation not supported */ > #define EPFNOSUPPORT 96 /* Protocol family not supported */ > #define EAFNOSUPPORT 97 /* Address family not supported by protocol */ > #define EADDRINUSE 98 /* Address already in use */ >=20 > base-commit: 670b77dfebe7257adc0defbc48a4c43cfdf6c8f6 This seems ill-advised. The problem is that most of this behavior has been well established for years, and not all userland software (and even some internal callers like nfsd), will react well when you go changing behavior like this. As a case in point, the POSIX spec doesn't list EOPNOTSUPP as a valid error return for open(): https://pubs.opengroup.org/onlinepubs/9690949399/functions/open.html The manpage for open() says only: EOPNOTSUPP The filesystem containing pathname does not support O_TMPFILE= . What is the poor userland developer to make of this when open() starts returning EOPNOTSUPP without O_TMPFILE being specified? --=20 Jeff Layton