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Date: Thu, 28 Mar 2024 18:53:33 -0700
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Subject: [RFC PATCH v4 18/36] fuse-bpf: Add support for FUSE_COPY_FILE_RANGE
From: Daniel Rosenberg <drosen@google.com>
To: Miklos Szeredi <miklos@szeredi.hu>, bpf@vger.kernel.org, 
	Alexei Starovoitov <ast@kernel.org>
Cc: Amir Goldstein <amir73il@gmail.com>, linux-kernel@vger.kernel.org, 
	linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org, 
	Daniel Borkmann <daniel@iogearbox.net>, John Fastabend <john.fastabend@gmail.com>, 
	Andrii Nakryiko <andrii@kernel.org>, Martin KaFai Lau <martin.lau@linux.dev>, Song Liu <song@kernel.org>, 
	Eduard Zingerman <eddyz87@gmail.com>, Yonghong Song <yonghong.song@linux.dev>, 
	KP Singh <kpsingh@kernel.org>, Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>, 
	Jiri Olsa <jolsa@kernel.org>, Shuah Khan <shuah@kernel.org>, Jonathan Corbet <corbet@lwn.net>, 
	Joanne Koong <joannelkoong@gmail.com>, Mykola Lysenko <mykolal@fb.com>, 
	Christian Brauner <brauner@kernel.org>, kernel-team@android.com, 
	Daniel Rosenberg <drosen@google.com>, Paul Lawrence <paullawrence@google.com>
Content-Type: text/plain; charset="UTF-8"

This adds backing support for FUSE_COPY_FILE_RANGE

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
---
 fs/fuse/backing.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/file.c    |  4 +++
 fs/fuse/fuse_i.h  | 10 ++++++
 3 files changed, 101 insertions(+)

diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index e426268aa4e6..2363f392e915 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -11,6 +11,7 @@
 #include <linux/file.h>
 #include <linux/fs_stack.h>
 #include <linux/namei.h>
+#include <linux/splice.h>
 #include <linux/uio.h>
 
 /*
@@ -778,6 +779,92 @@ int fuse_bpf_lseek(loff_t *out, struct inode *inode, struct file *file, loff_t o
 				file, offset, whence);
 }
 
+struct fuse_copy_file_range_args {
+	struct fuse_copy_file_range_in in;
+	struct fuse_write_out out;
+};
+
+static int fuse_copy_file_range_initialize_in(struct bpf_fuse_args *fa,
+					      struct fuse_copy_file_range_args *args,
+					      struct file *file_in, loff_t pos_in, struct file *file_out,
+					      loff_t pos_out, size_t len, unsigned int flags)
+{
+	struct fuse_file *fuse_file_in = file_in->private_data;
+	struct fuse_file *fuse_file_out = file_out->private_data;
+
+	args->in = (struct fuse_copy_file_range_in) {
+		.fh_in = fuse_file_in->fh,
+		.off_in = pos_in,
+		.nodeid_out = fuse_file_out->nodeid,
+		.fh_out = fuse_file_out->fh,
+		.off_out = pos_out,
+		.len = len,
+		.flags = flags,
+	};
+
+	*fa = (struct bpf_fuse_args) {
+		.info = (struct bpf_fuse_meta_info) {
+			.nodeid = get_node_id(file_in->f_inode),
+			.opcode = FUSE_COPY_FILE_RANGE,
+		},
+		.in_numargs = 1,
+		.in_args[0].size = sizeof(args->in),
+		.in_args[0].value = &args->in,
+	};
+
+	return 0;
+}
+
+static int fuse_copy_file_range_initialize_out(struct bpf_fuse_args *fa,
+					       struct fuse_copy_file_range_args *args,
+					       struct file *file_in, loff_t pos_in, struct file *file_out,
+					       loff_t pos_out, size_t len, unsigned int flags)
+{
+	fa->out_numargs = 1;
+	fa->out_args[0].size = sizeof(args->out);
+	fa->out_args[0].value = &args->out;
+
+	return 0;
+}
+
+static int fuse_copy_file_range_backing(struct bpf_fuse_args *fa, ssize_t *out, struct file *file_in,
+					loff_t pos_in, struct file *file_out, loff_t pos_out, size_t len,
+					unsigned int flags)
+{
+	const struct fuse_copy_file_range_in *fci = fa->in_args[0].value;
+	struct fuse_file *fuse_file_in = file_in->private_data;
+	struct file *backing_file_in = fuse_file_in->backing_file;
+	struct fuse_file *fuse_file_out = file_out->private_data;
+	struct file *backing_file_out = fuse_file_out->backing_file;
+
+	/* TODO: Handle changing of in/out files */
+	if (backing_file_out)
+		*out = vfs_copy_file_range(backing_file_in, fci->off_in, backing_file_out,
+					   fci->off_out, fci->len, fci->flags);
+	else
+		*out = splice_copy_file_range(file_in, pos_in, file_out, pos_out, len);
+	return 0;
+}
+
+static int fuse_copy_file_range_finalize(struct bpf_fuse_args *fa, ssize_t *out, struct file *file_in,
+					 loff_t pos_in, struct file *file_out, loff_t pos_out, size_t len,
+					 unsigned int flags)
+{
+	return 0;
+}
+
+int fuse_bpf_copy_file_range(ssize_t *out, struct inode *inode, struct file *file_in,
+			     loff_t pos_in, struct file *file_out, loff_t pos_out, size_t len,
+			     unsigned int flags)
+{
+	return bpf_fuse_backing(inode, struct fuse_copy_file_range_args, out,
+				fuse_copy_file_range_initialize_in,
+				fuse_copy_file_range_initialize_out,
+				fuse_copy_file_range_backing,
+				fuse_copy_file_range_finalize,
+				file_in, pos_in, file_out, pos_out, len, flags);
+}
+
 static int fuse_fsync_initialize_in(struct bpf_fuse_args *fa, struct fuse_fsync_in *in,
 				    struct file *file, loff_t start, loff_t end, int datasync)
 {
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 5983faf59c1f..46de67810f03 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -3168,6 +3168,10 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
 	bool is_unstable = (!fc->writeback_cache) &&
 			   ((pos_out + len) > inode_out->i_size);
 
+	if (fuse_bpf_copy_file_range(&err, file_inode(file_in), file_in, pos_in,
+				     file_out, pos_out, len, flags))
+		return err;
+
 	if (fc->no_copy_file_range)
 		return -EOPNOTSUPP;
 
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 61a17071ab02..a95d543c79ae 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1454,6 +1454,9 @@ int fuse_bpf_release(int *out, struct inode *inode, struct fuse_file *ff);
 int fuse_bpf_releasedir(int *out, struct inode *inode, struct fuse_file *ff);
 int fuse_bpf_flush(int *out, struct inode *inode, struct file *file, fl_owner_t id);
 int fuse_bpf_lseek(loff_t *out, struct inode *inode, struct file *file, loff_t offset, int whence);
+int fuse_bpf_copy_file_range(ssize_t *out, struct inode *inode, struct file *file_in, loff_t pos_in,
+			     struct file *file_out, loff_t pos_out,
+			     size_t len, unsigned int flags);
 int fuse_bpf_fsync(int *out, struct inode *inode, struct file *file, loff_t start, loff_t end, int datasync);
 int fuse_bpf_dir_fsync(int *out, struct inode *inode, struct file *file, loff_t start, loff_t end, int datasync);
 int fuse_bpf_file_read_iter(ssize_t *out, struct inode *inode, struct kiocb *iocb, struct iov_iter *to);
@@ -1533,6 +1536,13 @@ static inline int fuse_bpf_lseek(loff_t *out, struct inode *inode, struct file *
 	return 0;
 }
 
+static inline int fuse_bpf_copy_file_range(ssize_t *out, struct inode *inode, struct file *file_in, loff_t pos_in,
+					   struct file *file_out, loff_t pos_out,
+					   size_t len, unsigned int flags)
+{
+	return 0;
+}
+
 static inline int fuse_bpf_fsync(int *out, struct inode *inode, struct file *file, loff_t start, loff_t end, int datasync)
 {
 	return 0;
-- 
2.44.0.478.gd926399ef9-goog