From 37966b8d2463bb0262b8ccff223ad821e811eca4 Mon Sep 17 00:00:00 2001
From: Daniel Rosenberg <drosen@google.com>
Date: Mon, 7 Feb 2022 16:01:56 -0800
Subject: [PATCH] UPSTREAM: ANDROID: fuse: add bpf support for removexattr

Bug: 218393120
Test: fuse_test#bpf_test_xattr
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Change-Id: Idf69b5b70c5dc5f09270146fe8c574ac1bde7be6
---
 fs/fuse/backing.c | 33 +++++++++++++++++++++++++++++++++
 fs/fuse/fuse_i.h  |  8 ++++++++
 fs/fuse/xattr.c   |  9 ++++++++-
 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index 98f65cde6bdc..8da15a080c8f 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -661,6 +661,39 @@ void *fuse_setxattr_finalize(struct fuse_args *fa, struct dentry *dentry,
 	return NULL;
 }
 
+int fuse_removexattr_initialize(struct fuse_args *fa,
+				struct fuse_dummy_io *unused,
+				struct dentry *dentry, const char *name)
+{
+	*fa = (struct fuse_args) {
+		.nodeid = get_fuse_inode(dentry->d_inode)->nodeid,
+		.opcode = FUSE_REMOVEXATTR,
+		.in_numargs = 1,
+		.in_args[0] = (struct fuse_in_arg) {
+			.size = strlen(name) + 1,
+			.value = name,
+		},
+	};
+
+	return 0;
+}
+
+int fuse_removexattr_backing(struct fuse_args *fa,
+			     struct dentry *dentry, const char *name)
+{
+	struct path *backing_path =
+		&get_fuse_dentry(dentry)->backing_path;
+
+	/* TODO account for changes of the name by prefilter */
+	return vfs_removexattr(backing_path->dentry, name);
+}
+
+void *fuse_removexattr_finalize(struct fuse_args *fa,
+				struct dentry *dentry, const char *name)
+{
+	return NULL;
+}
+
 int fuse_file_read_iter_initialize(
 		struct fuse_args *fa, struct fuse_read_in *fri,
 		struct kiocb *iocb, struct iov_iter *to)
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 47bcd722a88b..f4b6f4366ff7 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1474,6 +1474,14 @@ void *fuse_setxattr_finalize(struct fuse_args *fa, struct dentry *dentry,
 			     const char *name, const void *value, size_t size,
 			     int flags);
 
+int fuse_removexattr_initialize(struct fuse_args *fa,
+				struct fuse_dummy_io *unused,
+				struct dentry *dentry, const char *name);
+int fuse_removexattr_backing(struct fuse_args *fa,
+			     struct dentry *dentry, const char *name);
+void *fuse_removexattr_finalize(struct fuse_args *fa,
+				struct dentry *dentry, const char *name);
+
 int fuse_file_read_iter_initialize(
 		struct fuse_args *fa, struct fuse_read_in *fri,
 		struct kiocb *iocb, struct iov_iter *to);
diff --git a/fs/fuse/xattr.c b/fs/fuse/xattr.c
index 3f09fa38d412..3abdf0e2be89 100644
--- a/fs/fuse/xattr.c
+++ b/fs/fuse/xattr.c
@@ -217,10 +217,17 @@ static int fuse_xattr_set(const struct xattr_handler *handler,
 #ifdef CONFIG_FUSE_BPF
 	struct fuse_err_ret fer;
 
-	fer = fuse_bpf_backing(inode, struct fuse_setxattr_in,
+	if (value)
+		fer = fuse_bpf_backing(inode, struct fuse_setxattr_in,
 			       fuse_setxattr_initialize, fuse_setxattr_backing,
 			       fuse_setxattr_finalize, dentry, name, value,
 			       size, flags);
+	else
+		fer = fuse_bpf_backing(inode, struct fuse_dummy_io,
+				       fuse_removexattr_initialize,
+				       fuse_removexattr_backing,
+				       fuse_removexattr_finalize,
+				       dentry, name);
 	if (fer.ret)
 		return PTR_ERR(fer.result);
 #endif