[PATCH 6.4 784/800] ovl: let helper ovl_i_path_real() return the realinode

Greg Kroah-Hartman
2023-07-16T20:29:34Z

From: Zhihao Cheng <chengzhihao1@huawei.com>

commit b2dd05f107b11966e26fe52a313b418364cf497b upstream.

Let helper ovl_i_path_real() return the realinode to prepare for
checking non-null realinode in RCU walking path.

[msz] Use d_inode_rcu() since we are depending on the consitency
between dentry and inode being non-NULL in an RCU setting.

Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Fixes: ffa5723c6d25 ("ovl: store lower path in ovl_inode")
Cc: <stable@vger.kernel.org> # v5.19
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/overlayfs/overlayfs.h | 2 +-
fs/overlayfs/util.c | 7 ++++---
2 files changed, 5 insertions(+), 4 deletions(-)

--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -384,7 +384,7 @@ enum ovl_path_type ovl_path_type(struct
void ovl_path_upper(struct dentry *dentry, struct path *path);
void ovl_path_lower(struct dentry *dentry, struct path *path);
void ovl_path_lowerdata(struct dentry *dentry, struct path *path);
-void ovl_i_path_real(struct inode *inode, struct path *path);
+struct inode *ovl_i_path_real(struct inode *inode, struct path *path);
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path);
struct dentry *ovl_dentry_upper(struct dentry *dentry);
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -266,7 +266,7 @@ struct dentry *ovl_i_dentry_upper(struct
return ovl_upperdentry_dereference(OVL_I(inode));
}

-void ovl_i_path_real(struct inode *inode, struct path *path)
+struct inode *ovl_i_path_real(struct inode *inode, struct path *path)
{
path->dentry = ovl_i_dentry_upper(inode);
if (!path->dentry) {
@@ -275,6 +275,8 @@ void ovl_i_path_real(struct inode *inode
} else {
path->mnt = ovl_upper_mnt(OVL_FS(inode->i_sb));
}
+
+ return path->dentry ? d_inode_rcu(path->dentry) : NULL;
}

struct inode *ovl_inode_upper(struct inode *inode)
@@ -1121,8 +1123,7 @@ void ovl_copyattr(struct inode *inode)
vfsuid_t vfsuid;
vfsgid_t vfsgid;

- ovl_i_path_real(inode, &realpath);
- realinode = d_inode(realpath.dentry);
+ realinode = ovl_i_path_real(inode, &realpath);
real_idmap = mnt_idmap(realpath.mnt);

vfsuid = i_uid_into_vfsuid(real_idmap, realinode);