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[70.77.216.213]) by smtp.gmail.com with ESMTPSA id r24sm21302038pfh.69.2019.10.22.15.13.57 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 22 Oct 2019 15:14:10 -0700 (PDT) From: Andreas Dilger Message-Id: <8CE5B6E8-DCB7-4F0B-91C1-48030947F585@dilger.ca> Content-Type: multipart/signed; boundary="Apple-Mail=_37420EF0-273E-43F4-97D0-62F6238C01CC"; protocol="application/pgp-signature"; micalg=pgp-sha256 Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: [PATCH v14 1/5] Add flags option to get xattr method paired to __vfs_getxattr Date: Tue, 22 Oct 2019 16:13:53 -0600 In-Reply-To: <20191022204453.97058-2-salyzyn@android.com> Cc: Linux Kernel Mailing List , kernel-team@android.com, Jan Kara , Jeff Layton , David Sterba , "Darrick J . Wong" , Mike Marshall , Stephen Smalley , linux-security-module@vger.kernel.org, Jonathan Corbet , Eric Van Hensbergen , Latchesar Ionkov , Dominique Martinet , David Howells , Chris Mason , Josef Bacik , Sage Weil , Ilya Dryomov , Steve French , Tyler Hicks , Gao Xiang , Chao Yu , Jan Kara , Theodore Ts'o , Jaegeuk Kim , Miklos Szeredi , Bob Peterson , Andreas Gruenbacher , David Woodhouse , Richard Weinberger , Dave Kleikamp , Greg Kroah-Hartman , Tejun Heo , Trond Myklebust , Anna Schumaker , Mark Fasheh , Joel Becker , Joseph Qi , Martin Brandenburg , Alexander Viro , Phillip Lougher , Artem Bityutskiy , Adrian Hunter , linux-xfs , Hugh Dickins , "David S. Miller" , Serge Hallyn , James Morris , Mimi Zohar , Paul Moore , Eric Paris , Casey Schaufler , Eric Biggers , Mauro Carvalho Chehab , Benjamin Coddington , Mathieu Malaterre , Andrew Morton , Bharath Vedartham , Jann Horn , Dave Chinner , Brian Foster , Eric Sandeen , linux-doc@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-afs@lists.infradead.org, linux-btrfs , ceph-devel , CIFS , samba-technical , ecryptfs@vger.kernel.org, linux-erofs@lists.ozlabs.org, Ext4 Developers List , linux-f2fs-devel@lists.sourceforge.net, Linux FS-devel Mailing List , cluster-devel@redhat.com, linux-mtd@lists.infradead.org, jfs-discussion@lists.sourceforge.net, linux-nfs , ocfs2-devel@oss.oracle.com, devel@lists.orangefs.org, overlayfs , reiserfs-devel@vger.kernel.org, linux-mm , netdev@vger.kernel.org, linux-integrity@vger.kernel.org, selinux@vger.kernel.org To: Mark Salyzyn References: <20191022204453.97058-1-salyzyn@android.com> <20191022204453.97058-2-salyzyn@android.com> X-Mailer: Apple Mail (2.3273) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: --Apple-Mail=_37420EF0-273E-43F4-97D0-62F6238C01CC Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii On Oct 22, 2019, at 2:44 PM, Mark Salyzyn wrote: >=20 > Replace arguments for get and set xattr methods, and __vfs_getxattr > and __vfs_setaxtr functions with a reference to the following now > common argument structure: >=20 > struct xattr_gs_args { > struct dentry *dentry; > struct inode *inode; > const char *name; > union { > void *buffer; > const void *value; > }; > size_t size; > int flags; > }; As part of this change (which is touching all of the uses of these fields anyway) it would be useful to give these structure fields a prefix like "xga_" so that they can be easily found with tags. Otherwise, there are so many different "dentry" and "inode" fields in various structures that it is hard to find the right one. > #define __USE_KERNEL_XATTR_DEFS >=20 > -#define XATTR_CREATE 0x1 /* set value, fail if attr already = exists */ > -#define XATTR_REPLACE 0x2 /* set value, fail if attr does = not exist */ > +#define XATTR_CREATE 0x1 /* set value, fail if attr already = exists */ > +#define XATTR_REPLACE 0x2 /* set value, fail if attr does = not exist */ > +#ifdef __KERNEL__ /* following is kernel internal, colocated for = maintenance */ > +#define XATTR_NOSECURITY 0x4 /* get value, do not involve security = check */ > +#endif Now that these arguments are separated out into their own structure, rather than using "int flags" (there are a million different flags in the kernel and easily confused) it would be immediately clear *which* flags are used here with a named enum, like: enum xattr_flags { XATTR_CREATE =3D 0x1, /* set value, fail if attr = already exists */ XATTR_REPLACE =3D 0x2, /* set value, fail if attr does = not exist */ #ifdef __KERNEL__ /* following is kernel internal, colocated for = maintenance */ XATTR_NOSECURITY=3D 0x4, /* get value, do not involve security = check */ #endif }; and use this in the struct like: struct xattr_gs_args { struct dentry *xga_dentry; struct inode *xga_inode; const char *xga_name; union { void *xga_buffer; const void *xga_value; }; size_t xga_size; enum xattr_flags xga_flags; }; Beyond the benefit for the reader to understand the code better, this can also allow the compiler to warn if incorrect values are being assigned to this field. Cheers, Andreas --Apple-Mail=_37420EF0-273E-43F4-97D0-62F6238C01CC Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQIzBAEBCAAdFiEEDb73u6ZejP5ZMprvcqXauRfMH+AFAl2vfyEACgkQcqXauRfM H+AxqxAAq6h17WEPF6r1UpAZIwUiPfdUH5qvEj5YwdktQwWuj4vM4AD1SnRYnDv2 erszJKsHxSS8RBP18hvIK3TC7Z1TwOPYxRcZb1KRnxX0TthhtHTNL103RmQvUvKm 8KjV2ZmRZAlgrvw09BGHJF4f4ina+Ua1AQsIg7l+6eGjBHJ3Nvjmv3M/Eca3Y9Gx eWYOM5vlA7+eVqKpCEyQ+/EN5lhBOWA+qsQhfEyPjSns/VsVae7bWkUrZSIRHpk9 i7HCwOkDj9cmfU4iZ34JePW8dtqHfoq3ECMUvsO681CznbyWB7yDnmX+UL8OFw2s Vj2n0fIHc/r3SJ87LF/k5JhjWaYM4rCM+1+uzXmukWQWXIU2U2vkLdAPkyibo6nq 5/Z98+GzWMwnP9esRhIM1lAf2Q0QQ/Bmmz5/2rwCEYpleEKInHDZyJ3ddSCC9mxQ +bf/9EeqBVd7b2R8rQLNcrY9R5zewIE+NovyaCcz71H6lyQ/NwfAAlUrjXN6zjGo aZYq3D2plzK5PnJwZrmarfiI2Qtge9h2sbFNX2dRT6oLeZNzv/rAx/8AueYIcGjb bPlf+rGFqzCVPkUQFPYqlsa/oEqUTnmr+6p8FvKO8DJhdVZEuOn/vJZV4e903hHl VURWEhW1Djzh/zWJVrNeOQRk+0KBXXfgvZ9nHpMRbX0xESTU+cY= =8Giq -----END PGP SIGNATURE----- --Apple-Mail=_37420EF0-273E-43F4-97D0-62F6238C01CC--