[RFC PATCH v4 06/36] fuse-bpf: Don't support export_operations

Daniel Rosenberg
2024-03-29T01:54:13Z

In the future, we may choose to support these, but it poses some
challenges. In order to create a disconnected dentry/inode, we'll need
to encode the mountpoint and bpf into the file_handle, which means we'd
need a stable representation of them. This also won't hold up to cases
where the bpf is not stateless. One possibility is registering bpf
programs and mounts in a specific order, so they can be assigned
consistent ids we can use in the file_handle. We can defer to the lower
filesystem for the lower inode's representation in the file_handle.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
---
fs/fuse/inode.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 6570fe7a9b53..b47b2e41e5e4 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1187,6 +1187,14 @@ static int fuse_encode_fh(struct inode *inode, u32 *fh, int *max_len,
nodeid = get_fuse_inode(inode)->nodeid;
generation = inode->i_generation;

+#ifdef CONFIG_FUSE_BPF
+ /* TODO: Does it make sense to support this in some cases? */
+ if (!nodeid && get_fuse_inode(inode)->backing_inode) {
+ *max_len = 0;
+ return FILEID_INVALID;
+ }
+#endif
+
fh[0] = (u32)(nodeid >> 32);
fh[1] = (u32)(nodeid & 0xffffffff);
fh[2] = generation;
--
2.44.0.478.gd926399ef9-goog