diff mbox series

[11/26] fuse-bpf: Add lseek support

Message ID 20220926231822.994383-12-drosen@google.com (mailing list archive)
State New, archived
Headers show
Series FUSE BPF: A Stacked Filesystem Extension for FUSE | expand

Commit Message

Daniel Rosenberg Sept. 26, 2022, 11:18 p.m. UTC 
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
---
 fs/fuse/backing.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/file.c    |  8 +++++
 fs/fuse/fuse_i.h  | 15 +++++++++-
 3 files changed, 96 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index fa8805e24061..97e92c633cfd 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -77,6 +77,80 @@  int parse_fuse_entry_bpf(struct fuse_entry_bpf *feb)
 	return err;
 }
 
+int fuse_lseek_initialize_in(struct bpf_fuse_args *fa, struct fuse_lseek_io *flio,
+			     struct file *file, loff_t offset, int whence)
+{
+	struct fuse_file *fuse_file = file->private_data;
+
+	flio->fli = (struct fuse_lseek_in) {
+		.fh = fuse_file->fh,
+		.offset = offset,
+		.whence = whence,
+	};
+
+	*fa = (struct bpf_fuse_args) {
+		.nodeid = get_node_id(file->f_inode),
+		.opcode = FUSE_LSEEK,
+		.in_numargs = 1,
+		.in_args[0].size = sizeof(flio->fli),
+		.in_args[0].value = &flio->fli,
+	};
+
+	return 0;
+}
+
+int fuse_lseek_initialize_out(struct bpf_fuse_args *fa, struct fuse_lseek_io *flio,
+			      struct file *file, loff_t offset, int whence)
+{
+	fa->out_numargs = 1;
+	fa->out_args[0].size = sizeof(flio->flo);
+	fa->out_args[0].value = &flio->flo;
+
+	return 0;
+}
+
+int fuse_lseek_backing(struct bpf_fuse_args *fa, loff_t *out,
+		       struct file *file, loff_t offset, int whence)
+{
+	const struct fuse_lseek_in *fli = fa->in_args[0].value;
+	struct fuse_lseek_out *flo = fa->out_args[0].value;
+	struct fuse_file *fuse_file = file->private_data;
+	struct file *backing_file = fuse_file->backing_file;
+
+	/* TODO: Handle changing of the file handle */
+	if (offset == 0) {
+		if (whence == SEEK_CUR) {
+			flo->offset = file->f_pos;
+			*out = flo->offset;
+			return 0;
+		}
+
+		if (whence == SEEK_SET) {
+			flo->offset = vfs_setpos(file, 0, 0);
+			*out = flo->offset;
+			return 0;
+		}
+	}
+
+	inode_lock(file->f_inode);
+	backing_file->f_pos = file->f_pos;
+	*out = vfs_llseek(backing_file, fli->offset, fli->whence);
+	flo->offset = *out;
+	inode_unlock(file->f_inode);
+	return 0;
+}
+
+int fuse_lseek_finalize(struct bpf_fuse_args *fa, loff_t *out,
+			struct file *file, loff_t offset, int whence)
+{
+	struct fuse_lseek_out *flo = fa->out_args[0].value;
+
+	if (!fa->error_in)
+		file->f_pos = flo->offset;
+	*out = flo->offset;
+	return 0;
+}
+
 ssize_t fuse_backing_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	int ret;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 138890eae07c..dd4485261cc7 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2703,6 +2703,14 @@  static loff_t fuse_file_llseek(struct file *file, loff_t offset, int whence)
 {
 	loff_t retval;
 	struct inode *inode = file_inode(file);
+#ifdef CONFIG_FUSE_BPF
+	if (fuse_bpf_backing(inode, struct fuse_lseek_io, retval,
+			       fuse_lseek_initialize_in, fuse_lseek_initialize_out,
+			       fuse_lseek_backing,
+			       fuse_lseek_finalize,
+			       file, offset, whence))
+		return retval;
+#endif
 
 	switch (whence) {
 	case SEEK_SET:
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index a9653f71c145..fc3e8adf0422 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1404,9 +1404,22 @@  struct fuse_entry_bpf {
 	struct bpf_prog *bpf;
 };
 
-
 int parse_fuse_entry_bpf(struct fuse_entry_bpf *feb);
 
+struct fuse_lseek_io {
+	struct fuse_lseek_in fli;
+	struct fuse_lseek_out flo;
+};
+
+int fuse_lseek_initialize_in(struct bpf_fuse_args *fa, struct fuse_lseek_io *fli,
+			     struct file *file, loff_t offset, int whence);
+int fuse_lseek_initialize_out(struct bpf_fuse_args *fa, struct fuse_lseek_io *fli,
+			      struct file *file, loff_t offset, int whence);
+int fuse_lseek_backing(struct bpf_fuse_args *fa, loff_t *out, struct file *file,
+		       loff_t offset, int whence);
+int fuse_lseek_finalize(struct bpf_fuse_args *fa, loff_t *out, struct file *file,
+			loff_t offset, int whence);
+
 ssize_t fuse_backing_mmap(struct file *file, struct vm_area_struct *vma);
 
 struct fuse_lookup_io {