ANDROID: fuse-bpf: Get correct inode in mkdir

We were getting the inode with the parent inode info
Also change variable names to remove confusion
Also set bpf correctly in new inode

Bug: 293838958
Test: fuse_test, atest ScopedStorageDeviceTest,
	atest CtsScopedStorageHostTest
Change-Id: I0b6a6951599e0d211afd2243daacb98679503448
Signed-off-by: Paul Lawrence <paullawrence@google.com>

fs/fuse/backing.c

@@ -1446,32 +1446,34 @@ int fuse_mkdir_initialize(
 
 int fuse_mkdir_backing(
 		struct fuse_bpf_args *fa,
-		struct inode *dir, struct dentry *entry, umode_t mode)
+		struct inode *dir_inode, struct dentry *entry, umode_t mode)
 {
 	int err = 0;
 	const struct fuse_mkdir_in *fmi = fa->in_args[0].value;
-	struct fuse_inode *fuse_inode = get_fuse_inode(dir);
-	struct inode *backing_inode = fuse_inode->backing_inode;
+	struct fuse_inode *dir_fuse_inode = get_fuse_inode(dir_inode);
+	struct inode *dir_backing_inode = dir_fuse_inode->backing_inode;
 	struct path backing_path = {};
 	struct inode *inode = NULL;
-	struct dentry *d;
 
 	//TODO Actually deal with changing the backing entry in mkdir
 	get_fuse_backing_path(entry, &backing_path);
 	if (!backing_path.dentry)
 		return -EBADF;
 
-	inode_lock_nested(backing_inode, I_MUTEX_PARENT);
+	inode_lock_nested(dir_backing_inode, I_MUTEX_PARENT);
 	mode = fmi->mode;
-	if (!IS_POSIXACL(backing_inode))
+	if (!IS_POSIXACL(dir_backing_inode))
 		mode &= ~fmi->umask;
-	err = vfs_mkdir(&init_user_ns, backing_inode, backing_path.dentry, mode);
+	err = vfs_mkdir(&init_user_ns, dir_backing_inode, backing_path.dentry,
+			mode);
 	if (err)
 		goto out;
 	if (d_really_is_negative(backing_path.dentry) ||
 		unlikely(d_unhashed(backing_path.dentry))) {
-		d = lookup_one_len(entry->d_name.name, backing_path.dentry->d_parent,
-				entry->d_name.len);
+		struct dentry *d = lookup_one_len(entry->d_name.name,
+					backing_path.dentry->d_parent,
+					entry->d_name.len);
+
 		if (IS_ERR(d)) {
 			err = PTR_ERR(d);
 			goto out;
@@ -1479,14 +1481,19 @@ int fuse_mkdir_backing(
 		dput(backing_path.dentry);
 		backing_path.dentry = d;
 	}
-	inode = fuse_iget_backing(dir->i_sb, fuse_inode->nodeid, backing_inode);
+	inode = fuse_iget_backing(dir_inode->i_sb, 0,
+				  backing_path.dentry->d_inode);
 	if (IS_ERR(inode)) {
 		err = PTR_ERR(inode);
 		goto out;
 	}
 	d_instantiate(entry, inode);
+	if (get_fuse_inode(inode)->bpf)
+		bpf_prog_put(get_fuse_inode(inode)->bpf);
+	get_fuse_inode(inode)->bpf = get_fuse_dentry(entry)->bpf;
+	get_fuse_dentry(entry)->bpf = NULL;
 out:
-	inode_unlock(backing_inode);
+	inode_unlock(dir_backing_inode);
 	path_put(&backing_path);
 	return err;
 }

tools/testing/selftests/filesystems/fuse/fuse_test.c

@@ -2047,6 +2047,38 @@ static int bpf_test_create_and_remove_bpf(const char *mount_dir)
 	return result;
 }
 
+static int bpf_test_mkdir_and_remove_bpf(const char *mount_dir)
+{
+	const char *dir = "dir";
+
+	int result = TEST_FAILURE;
+	int src_fd = -1;
+	int bpf_fd = -1;
+	int fuse_dev = -1;
+	int fd = -1;
+	int fd2 = -1;
+
+	TEST(src_fd = open(ft_src, O_DIRECTORY | O_RDONLY | O_CLOEXEC),
+	     src_fd != -1);
+	TESTEQUAL(install_elf_bpf("test_bpf.bpf", "test_mkdir_remove", &bpf_fd,
+				  NULL, NULL), 0);
+	TESTEQUAL(mount_fuse_no_init(mount_dir, bpf_fd, src_fd, &fuse_dev), 0);
+	TEST(fd = s_mkdir(s_path(s(mount_dir), s(dir)), 0777),
+	     fd != -1);
+	TEST(fd2 = s_open(s_path(s(mount_dir), s(dir)), O_RDONLY),
+	     fd2 != -1);
+
+	result = TEST_SUCCESS;
+out:
+	close(fd2);
+	close(fd);
+	close(fuse_dev);
+	close(bpf_fd);
+	close(src_fd);
+	umount(mount_dir);
+	return result;
+}
+
 static void parse_range(const char *ranges, bool *run_test, size_t tests)
 {
 	size_t i;
@@ -2175,6 +2207,7 @@ int main(int argc, char *argv[])
 		MAKE_TEST(bpf_test_lookup_postfilter),
 		MAKE_TEST(flock_test),
 		MAKE_TEST(bpf_test_create_and_remove_bpf),
+		MAKE_TEST(bpf_test_mkdir_and_remove_bpf),
 	};
 #undef MAKE_TEST
 

tools/testing/selftests/filesystems/fuse/test_bpf.c

@@ -530,4 +530,26 @@ int createremovebpf_test(struct fuse_bpf_args *fa)
 	}
 }
 
+SEC("test_mkdir_remove")
+int mkdirremovebpf_test(struct fuse_bpf_args *fa)
+{
+	switch (fa->opcode) {
+	case FUSE_LOOKUP | FUSE_PREFILTER: {
+		return FUSE_BPF_BACKING | FUSE_BPF_POST_FILTER;
+	}
 
+	case FUSE_LOOKUP | FUSE_POSTFILTER: {
+		struct fuse_entry_bpf_out *febo = fa->out_args[1].value;
+
+		febo->bpf_action = FUSE_ACTION_REMOVE;
+		return 0;
+	}
+
+	case FUSE_OPENDIR | FUSE_PREFILTER: {
+		return -EIO;
+	}
+
+	default:
+		return FUSE_BPF_BACKING;
+	}
+}