VFS: unify old_mnt_idmap and new_mnt_idmap in renamedata

A rename operation can only rename within a single mount.  Callers of
vfs_rename() must and do ensure this is the case.

So there is no point in having two mnt_idmaps in renamedata as they are
always the same.  Only one of them is passed to ->rename in any case.

This patch replaces both with a single "mnt_idmap" and changes all
callers.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: neilbrown

fs/cachefiles/namei.c

@@ -387,10 +387,9 @@ int cachefiles_bury_object(struct cachefiles_cache *cache,
 		cachefiles_io_error(cache, "Rename security error %d", ret);
 	} else {
 		struct renamedata rd = {
-			.old_mnt_idmap	= &nop_mnt_idmap,
+			.mnt_idmap	= &nop_mnt_idmap,
 			.old_parent	= dir,
 			.old_dentry	= rep,
-			.new_mnt_idmap	= &nop_mnt_idmap,
 			.new_parent	= cache->graveyard,
 			.new_dentry	= grave,
 		};

fs/ecryptfs/inode.c

@@ -634,10 +634,9 @@ ecryptfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
 		goto out_lock;
 	}
 
-	rd.old_mnt_idmap	= &nop_mnt_idmap;
+	rd.mnt_idmap		= &nop_mnt_idmap;
 	rd.old_parent		= lower_old_dir_dentry;
 	rd.old_dentry		= lower_old_dentry;
-	rd.new_mnt_idmap	= &nop_mnt_idmap;
 	rd.new_parent		= lower_new_dir_dentry;
 	rd.new_dentry		= lower_new_dentry;
 	rc = vfs_rename(&rd);

fs/namei.c

@@ -5077,20 +5077,20 @@ int vfs_rename(struct renamedata *rd)
 	if (source == target)
 		return 0;
 
-	error = may_delete(rd->old_mnt_idmap, old_dir, old_dentry, is_dir);
+	error = may_delete(rd->mnt_idmap, old_dir, old_dentry, is_dir);
 	if (error)
 		return error;
 
 	if (!target) {
-		error = may_create(rd->new_mnt_idmap, new_dir, new_dentry);
+		error = may_create(rd->mnt_idmap, new_dir, new_dentry);
 	} else {
 		new_is_dir = d_is_dir(new_dentry);
 
 		if (!(flags & RENAME_EXCHANGE))
-			error = may_delete(rd->new_mnt_idmap, new_dir,
+			error = may_delete(rd->mnt_idmap, new_dir,
 					   new_dentry, is_dir);
 		else
-			error = may_delete(rd->new_mnt_idmap, new_dir,
+			error = may_delete(rd->mnt_idmap, new_dir,
 					   new_dentry, new_is_dir);
 	}
 	if (error)
@@ -5105,13 +5105,13 @@ int vfs_rename(struct renamedata *rd)
 	 */
 	if (new_dir != old_dir) {
 		if (is_dir) {
-			error = inode_permission(rd->old_mnt_idmap, source,
+			error = inode_permission(rd->mnt_idmap, source,
 						 MAY_WRITE);
 			if (error)
 				return error;
 		}
 		if ((flags & RENAME_EXCHANGE) && new_is_dir) {
-			error = inode_permission(rd->new_mnt_idmap, target,
+			error = inode_permission(rd->mnt_idmap, target,
 						 MAY_WRITE);
 			if (error)
 				return error;
@@ -5179,7 +5179,7 @@ int vfs_rename(struct renamedata *rd)
 		if (error)
 			goto out;
 	}
-	error = old_dir->i_op->rename(rd->new_mnt_idmap, old_dir, old_dentry,
+	error = old_dir->i_op->rename(rd->mnt_idmap, old_dir, old_dentry,
 				      new_dir, new_dentry, flags);
 	if (error)
 		goto out;
@@ -5322,10 +5322,9 @@ int do_renameat2(int olddfd, struct filename *from, int newdfd,
 
 	rd.old_parent	   = old_path.dentry;
 	rd.old_dentry	   = old_dentry;
-	rd.old_mnt_idmap   = mnt_idmap(old_path.mnt);
+	rd.mnt_idmap	   = mnt_idmap(old_path.mnt);
 	rd.new_parent	   = new_path.dentry;
 	rd.new_dentry	   = new_dentry;
-	rd.new_mnt_idmap   = mnt_idmap(new_path.mnt);
 	rd.delegated_inode = &delegated_inode;
 	rd.flags	   = flags;
 	error = vfs_rename(&rd);

fs/nfsd/vfs.c

@@ -1943,10 +1943,9 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
 		goto out_dput_old;
 	} else {
 		struct renamedata rd = {
-			.old_mnt_idmap	= &nop_mnt_idmap,
+			.mnt_idmap	= &nop_mnt_idmap,
 			.old_parent	= fdentry,
 			.old_dentry	= odentry,
-			.new_mnt_idmap	= &nop_mnt_idmap,
 			.new_parent	= tdentry,
 			.new_dentry	= ndentry,
 		};

fs/overlayfs/overlayfs.h

@@ -361,10 +361,9 @@ static inline int ovl_do_rename(struct ovl_fs *ofs, struct dentry *olddir,
 {
 	int err;
 	struct renamedata rd = {
-		.old_mnt_idmap	= ovl_upper_mnt_idmap(ofs),
+		.mnt_idmap	= ovl_upper_mnt_idmap(ofs),
 		.old_parent	= olddir,
 		.old_dentry	= olddentry,
-		.new_mnt_idmap	= ovl_upper_mnt_idmap(ofs),
 		.new_parent	= newdir,
 		.new_dentry	= newdentry,
 		.flags		= flags,

fs/smb/server/vfs.c

@@ -770,10 +770,9 @@ int ksmbd_vfs_rename(struct ksmbd_work *work, const struct path *old_path,
 		goto out4;
 	}
 
-	rd.old_mnt_idmap	= mnt_idmap(old_path->mnt),
+	rd.mnt_idmap		= mnt_idmap(old_path->mnt),
 	rd.old_parent		= old_parent,
 	rd.old_dentry		= old_child,
-	rd.new_mnt_idmap	= mnt_idmap(new_path.mnt),
 	rd.new_parent		= new_path.dentry,
 	rd.new_dentry		= new_dentry,
 	rd.flags		= flags,

include/linux/fs.h

@@ -2008,20 +2008,18 @@ int vfs_unlink(struct mnt_idmap *, struct inode *, struct dentry *,
 
 /**
  * struct renamedata - contains all information required for renaming
- * @old_mnt_idmap:     idmap of the old mount the inode was found from
+ * @mnt_idmap:     idmap of the mount in which the rename is happening.
  * @old_parent:        parent of source
  * @old_dentry:                source
- * @new_mnt_idmap:     idmap of the new mount the inode was found from
  * @new_parent:        parent of destination
  * @new_dentry:                destination
  * @delegated_inode:   returns an inode needing a delegation break
  * @flags:             rename flags
  */
 struct renamedata {
-	struct mnt_idmap *old_mnt_idmap;
+	struct mnt_idmap *mnt_idmap;
 	struct dentry *old_parent;
 	struct dentry *old_dentry;
-	struct mnt_idmap *new_mnt_idmap;
 	struct dentry *new_parent;
 	struct dentry *new_dentry;
 	struct inode **delegated_inode;