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Mon, 22 Apr 2024 15:06:59 +0000 (GMT) From: Stefan Berger To: linux-integrity@vger.kernel.org, linux-unionfs@vger.kernel.org Cc: linux-kernel@vger.kernel.org, zohar@linux.ibm.com, roberto.sassu@huawei.com, amir73il@gmail.com, miklos@szeredi.hu, brauner@kernel.org, Stefan Berger Subject: [RFC PATCH v2 1/2] ovl: Define D_REAL_FILEDATA for d_real to return dentry with data Date: Mon, 22 Apr 2024 11:06:50 -0400 Message-ID: <20240422150651.2908169-2-stefanb@linux.ibm.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240422150651.2908169-1-stefanb@linux.ibm.com> References: <20240422150651.2908169-1-stefanb@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: BSjmWBvt92PLPKosiN5REeUDopk1TNUt X-Proofpoint-GUID: iOmg7h_3DNPC1Pc8_8sU5S8ir8steyM9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-04-22_09,2024-04-22_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 adultscore=0 clxscore=1015 malwarescore=0 mlxlogscore=999 impostorscore=0 spamscore=0 priorityscore=1501 mlxscore=0 phishscore=0 lowpriorityscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2404010000 definitions=main-2404220065 Define D_REAL_FILEDATA which is to be used as a parameter for d_real() to return the dentry that is holding the file data, which is either the upper or the lower denry. The caller is expected to call d_real() again on the returned dentry to get to lower layers of a stacked filesystem, if available. This allows a caller to get all dentries involved in hold a file's data and iterate through the layers. Signed-off-by: Stefan Berger --- fs/overlayfs/super.c | 6 ++++++ include/linux/dcache.h | 1 + 2 files changed, 7 insertions(+) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 06a231970cb5..f466ad89b005 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -36,6 +36,7 @@ static struct dentry *ovl_d_real(struct dentry *dentry, enum d_real_type type) switch (type) { case D_REAL_DATA: case D_REAL_METADATA: + case D_REAL_FILEDATA: break; default: goto bug; @@ -47,6 +48,11 @@ static struct dentry *ovl_d_real(struct dentry *dentry, enum d_real_type type) } upper = ovl_dentry_upper(dentry); + if (type == D_REAL_FILEDATA) { + if (ovl_has_upperdata(d_inode(dentry))) + return upper; + return ovl_dentry_lower(dentry); + } if (upper && (type == D_REAL_METADATA || ovl_has_upperdata(d_inode(dentry)))) return upper; diff --git a/include/linux/dcache.h b/include/linux/dcache.h index bf53e3894aae..e4e54fb2cf4e 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -128,6 +128,7 @@ enum dentry_d_lock_class enum d_real_type { D_REAL_DATA, D_REAL_METADATA, + D_REAL_FILEDATA, }; struct dentry_operations {