[PATCH 6.1 066/223] ovl: let helper ovl_i_path_real() return the realinode

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From: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>

[ Upstream commit b2dd05f107b11966e26fe52a313b418364cf497b ]

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.

There are some changes from upstream commit:
1. Context conflicts caused by 73db6a063c785bc ("ovl: port to
   vfs{g,u}id_t and associated helpers") is handled.

Signed-off-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Fixes: ffa5723c6d25 ("ovl: store lower path in ovl_inode")
Cc: <stable@xxxxxxxxxxxxxxx> # v5.19
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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
@@ -369,7 +369,7 @@ 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)
 	struct inode *realinode;
 	struct user_namespace *real_mnt_userns;
 
-	ovl_i_path_real(inode, &realpath);
-	realinode = d_inode(realpath.dentry);
+	realinode = ovl_i_path_real(inode, &realpath);
 	real_mnt_userns = mnt_user_ns(realpath.mnt);
 
 	inode->i_uid = i_uid_into_mnt(real_mnt_userns, realinode);





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