[RFC PATCH v3 19/37] fuse-bpf: Add support for sync operations

[Daniel Rosenberg <drosen@google.com>]

This adds backing support for FUSE_FLUSH, FUSE_FSYNC, and FUSE_FSYNCDIR.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
---
 fs/fuse/backing.c | 147 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/dir.c     |   3 +
 fs/fuse/file.c    |   7 +++
 fs/fuse/fuse_i.h  |  18 ++++++
 4 files changed, 175 insertions(+)

diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index 2908c231a695..30492f7b2a05 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -659,6 +659,59 @@ int fuse_bpf_releasedir(int *out, struct inode *inode, struct file *file)
 				fuse_release_backing, fuse_release_finalize, inode, file);
 }
 
+static int fuse_flush_initialize_in(struct bpf_fuse_args *fa, struct fuse_flush_in *ffi,
+				    struct file *file, fl_owner_t id)
+{
+	struct fuse_file *fuse_file = file->private_data;
+
+	*ffi = (struct fuse_flush_in) {
+		.fh = fuse_file->fh,
+	};
+
+	*fa = (struct bpf_fuse_args) {
+		.info = (struct bpf_fuse_meta_info) {
+			.nodeid = get_node_id(file->f_inode),
+			.opcode = FUSE_FLUSH,
+		},
+		.in_numargs = 1,
+		.in_args[0].size = sizeof(*ffi),
+		.in_args[0].value = ffi,
+		.flags = FUSE_BPF_FORCE,
+	};
+
+	return 0;
+}
+
+static int fuse_flush_initialize_out(struct bpf_fuse_args *fa, struct fuse_flush_in *ffi,
+				     struct file *file, fl_owner_t id)
+{
+	return 0;
+}
+
+static int fuse_flush_backing(struct bpf_fuse_args *fa, int *out, struct file *file, fl_owner_t id)
+{
+	struct fuse_file *fuse_file = file->private_data;
+	struct file *backing_file = fuse_file->backing_file;
+
+	*out = 0;
+	if (backing_file->f_op->flush)
+		*out = backing_file->f_op->flush(backing_file, id);
+	return *out;
+}
+
+static int fuse_flush_finalize(struct bpf_fuse_args *fa, int *out, struct file *file, fl_owner_t id)
+{
+	return 0;
+}
+
+int fuse_bpf_flush(int *out, struct inode *inode, struct file *file, fl_owner_t id)
+{
+	return bpf_fuse_backing(inode, struct fuse_flush_in, out,
+				fuse_flush_initialize_in, fuse_flush_initialize_out,
+				fuse_flush_backing, fuse_flush_finalize,
+				file, id);
+}
+
 struct fuse_lseek_args {
 	struct fuse_lseek_in in;
 	struct fuse_lseek_out out;
@@ -748,6 +801,100 @@ int fuse_bpf_lseek(loff_t *out, struct inode *inode, struct file *file, loff_t o
 				file, offset, whence);
 }
 
+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)
+{
+	struct fuse_file *fuse_file = file->private_data;
+
+	*in = (struct fuse_fsync_in) {
+		.fh = fuse_file->fh,
+		.fsync_flags = datasync ? FUSE_FSYNC_FDATASYNC : 0,
+	};
+
+	*fa = (struct bpf_fuse_args) {
+		.info = (struct bpf_fuse_meta_info) {
+			.nodeid = get_fuse_inode(file->f_inode)->nodeid,
+			.opcode = FUSE_FSYNC,
+		},
+		.in_numargs = 1,
+		.in_args[0].size = sizeof(*in),
+		.in_args[0].value = in,
+		.flags = FUSE_BPF_FORCE,
+	};
+
+	return 0;
+}
+
+static int fuse_fsync_initialize_out(struct bpf_fuse_args *fa, struct fuse_fsync_in *ffi,
+				     struct file *file, loff_t start, loff_t end, int datasync)
+{
+	return 0;
+}
+
+static int fuse_fsync_backing(struct bpf_fuse_args *fa, int *out,
+			      struct file *file, loff_t start, loff_t end, int datasync)
+{
+	struct fuse_file *fuse_file = file->private_data;
+	struct file *backing_file = fuse_file->backing_file;
+	const struct fuse_fsync_in *ffi = fa->in_args[0].value;
+	int new_datasync = (ffi->fsync_flags & FUSE_FSYNC_FDATASYNC) ? 1 : 0;
+
+	*out = vfs_fsync(backing_file, new_datasync);
+	return 0;
+}
+
+static int fuse_fsync_finalize(struct bpf_fuse_args *fa, int *out,
+			       struct file *file, loff_t start, loff_t end, int datasync)
+{
+	return 0;
+}
+
+int fuse_bpf_fsync(int *out, struct inode *inode, struct file *file, loff_t start, loff_t end, int datasync)
+{
+	return bpf_fuse_backing(inode, struct fuse_fsync_in, out,
+				fuse_fsync_initialize_in, fuse_fsync_initialize_out,
+				fuse_fsync_backing, fuse_fsync_finalize,
+				file, start, end, datasync);
+}
+
+static int fuse_dir_fsync_initialize_in(struct bpf_fuse_args *fa, struct fuse_fsync_in *in,
+					struct file *file, loff_t start, loff_t end, int datasync)
+{
+	struct fuse_file *fuse_file = file->private_data;
+
+	*in = (struct fuse_fsync_in) {
+		.fh = fuse_file->fh,
+		.fsync_flags = datasync ? FUSE_FSYNC_FDATASYNC : 0,
+	};
+
+	*fa = (struct bpf_fuse_args) {
+		.info = (struct bpf_fuse_meta_info) {
+			.nodeid = get_fuse_inode(file->f_inode)->nodeid,
+			.opcode = FUSE_FSYNCDIR,
+		},
+		.in_numargs = 1,
+		.in_args[0].size = sizeof(*in),
+		.in_args[0].value = in,
+		.flags = FUSE_BPF_FORCE,
+	};
+
+	return 0;
+}
+
+static int fuse_dir_fsync_initialize_out(struct bpf_fuse_args *fa, struct fuse_fsync_in *ffi,
+					 struct file *file, loff_t start, loff_t end, int datasync)
+{
+	return 0;
+}
+
+int fuse_bpf_dir_fsync(int *out, struct inode *inode, struct file *file, loff_t start, loff_t end, int datasync)
+{
+	return bpf_fuse_backing(inode, struct fuse_fsync_in, out,
+				fuse_dir_fsync_initialize_in, fuse_dir_fsync_initialize_out,
+				fuse_fsync_backing, fuse_fsync_finalize,
+				file, start, end, datasync);
+}
+
 static inline void fuse_bpf_aio_put(struct fuse_bpf_aio_req *aio_req)
 {
 	if (refcount_dec_and_test(&aio_req->ref))
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index a763a45fa973..5ce65f696980 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1666,6 +1666,9 @@ static int fuse_dir_fsync(struct file *file, loff_t start, loff_t end,
 	if (fuse_is_bad(inode))
 		return -EIO;
 
+	if (fuse_bpf_dir_fsync(&err, inode, file, start, end, datasync))
+		return err;
+
 	if (fc->no_fsyncdir)
 		return 0;
 
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 5f19ef5bf124..a4a0aeb28e4a 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -554,10 +554,14 @@ static int fuse_flush(struct file *file, fl_owner_t id)
 	struct inode *inode = file_inode(file);
 	struct fuse_mount *fm = get_fuse_mount(inode);
 	struct fuse_file *ff = file->private_data;
+	int err;
 
 	if (fuse_is_bad(inode))
 		return -EIO;
 
+	if (fuse_bpf_flush(&err, file_inode(file), file, id))
+		return err;
+
 	if (ff->open_flags & FOPEN_NOFLUSH && !fm->fc->writeback_cache)
 		return 0;
 
@@ -615,6 +619,9 @@ static int fuse_fsync(struct file *file, loff_t start, loff_t end,
 	if (fuse_is_bad(inode))
 		return -EIO;
 
+	if (fuse_bpf_fsync(&err, inode, file, start, end, datasync))
+		return err;
+
 	inode_lock(inode);
 
 	/*
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index fb3a77b79b0f..e60207bf66de 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1414,7 +1414,10 @@ int fuse_bpf_rmdir(int *out, struct inode *dir, struct dentry *entry);
 int fuse_bpf_unlink(int *out, struct inode *dir, struct dentry *entry);
 int fuse_bpf_release(int *out, struct inode *inode, struct file *file);
 int fuse_bpf_releasedir(int *out, struct inode *inode, struct file *file);
+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_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);
 int fuse_bpf_file_write_iter(ssize_t *out, struct inode *inode, struct kiocb *iocb, struct iov_iter *from);
 int fuse_bpf_file_fallocate(int *out, struct inode *inode, struct file *file, int mode, loff_t offset, loff_t length);
@@ -1465,11 +1468,26 @@ static inline int fuse_bpf_releasedir(int *out, struct inode *inode, struct file
 	return 0;
 }
 
+static inline int fuse_bpf_flush(int *out, struct inode *inode, struct file *file, fl_owner_t id)
+{
+	return 0;
+}
+
 static inline int fuse_bpf_lseek(loff_t *out, struct inode *inode, struct file *file, loff_t offset, int whence)
 {
 	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;
+}
+
+static inline int fuse_bpf_dir_fsync(int *out, struct inode *inode, struct file *file, loff_t start, loff_t end, int datasync)
+{
+	return 0;
+}
+
 static inline int fuse_bpf_file_read_iter(ssize_t *out, struct inode *inode, struct kiocb *iocb, struct iov_iter *to)
 {
 	return 0;
-- 
2.40.0.634.g4ca3ef3211-goog