On 11/27/24 13:40, Bernd Schubert wrote:
This adds basic support for ring SQEs (with opcode=IORING_OP_URING_CMD).
For now only FUSE_URING_REQ_FETCH is handled to register queue entries.
Signed-off-by: Bernd Schubert <bschubert@xxxxxxx>
---
fs/fuse/Kconfig | 12 ++
fs/fuse/Makefile | 1 +
fs/fuse/dev.c | 4 +
fs/fuse/dev_uring.c | 318 ++++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/dev_uring_i.h | 115 +++++++++++++++++
fs/fuse/fuse_i.h | 5 +
fs/fuse/inode.c | 10 ++
include/uapi/linux/fuse.h | 67 ++++++++++
8 files changed, 532 insertions(+)
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
new file mode 100644
index 0000000000000000000000000000000000000000..af9c5f116ba1dcf6c01d0359d1a06491c92c32f9
--- /dev/null
+++ b/fs/fuse/dev_uring.c
...
+
+/*
+ * fuse_uring_req_fetch command handling
+ */
+static void _fuse_uring_fetch(struct fuse_ring_ent *ring_ent,
+ struct io_uring_cmd *cmd,
+ unsigned int issue_flags)
+{
+ struct fuse_ring_queue *queue = ring_ent->queue;
+
+ spin_lock(&queue->lock);
+ fuse_uring_ent_avail(ring_ent, queue);
+ ring_ent->cmd = cmd;
+ spin_unlock(&queue->lock);
+}
+
+/*
+ * sqe->addr is a ptr to an iovec array, iov[0] has the headers, iov[1]
+ * the payload
+ */
+static int fuse_uring_get_iovec_from_sqe(const struct io_uring_sqe *sqe,
+ struct iovec iov[FUSE_URING_IOV_SEGS])
+{
+ struct iovec __user *uiov = u64_to_user_ptr(READ_ONCE(sqe->addr));
+ struct iov_iter iter;
+ ssize_t ret;
+
+ if (sqe->len != FUSE_URING_IOV_SEGS)
+ return -EINVAL;
+
+ /*
+ * Direction for buffer access will actually be READ and WRITE,
+ * using write for the import should include READ access as well.
+ */
+ ret = import_iovec(WRITE, uiov, FUSE_URING_IOV_SEGS,
+ FUSE_URING_IOV_SEGS, &iov, &iter);
You're throwing away the iterator, I'd be a bit cautious about it.
FUSE_URING_IOV_SEGS is 2, so it should avoid ITER_UBUF, but Jens
can say if it's abuse of the API or not.
Fwiw, it's not the first place I know of that just want to get
an iovec avoiding playing games with different iterator modes.
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+
+static int fuse_uring_fetch(struct io_uring_cmd *cmd, unsigned int issue_flags,
+ struct fuse_conn *fc)
+{
+ const struct fuse_uring_cmd_req *cmd_req = io_uring_sqe_cmd(cmd->sqe);
You need to check that the ring is setup with SQE128.
(!(issue_flags & IO_URING_F_SQE128))
// fail
+ struct fuse_ring *ring = fc->ring;
+ struct fuse_ring_queue *queue;
+ struct fuse_ring_ent *ring_ent;
+ int err;
+ struct iovec iov[FUSE_URING_IOV_SEGS];
+
+ err = fuse_uring_get_iovec_from_sqe(cmd->sqe, iov);
+ if (err) {
+ pr_info_ratelimited("Failed to get iovec from sqe, err=%d\n",
+ err);
+ return err;
+ }
+
+ err = -ENOMEM;
+ if (!ring) {
+ ring = fuse_uring_create(fc);
+ if (!ring)
+ return err;
+ }
+
+ queue = ring->queues[cmd_req->qid];
+ if (!queue) {
+ queue = fuse_uring_create_queue(ring, cmd_req->qid);
+ if (!queue)
+ return err;
+ }
+
+ /*
+ * The created queue above does not need to be destructed in
+ * case of entry errors below, will be done at ring destruction time.
+ */
+
+ ring_ent = kzalloc(sizeof(*ring_ent), GFP_KERNEL_ACCOUNT);
+ if (ring_ent == NULL)
+ return err;
+
+ INIT_LIST_HEAD(&ring_ent->list);
+
+ ring_ent->queue = queue;
+ ring_ent->cmd = cmd;
nit: seems it's also set immediately after in
_fuse_uring_fetch().
+
+ err = -EINVAL;
+ if (iov[0].iov_len < sizeof(struct fuse_uring_req_header)) {
+ pr_info_ratelimited("Invalid header len %zu\n", iov[0].iov_len);
+ goto err;
+ }
+
...
+/*
+ * Entry function from io_uring to handle the given passthrough command
+ * (op cocde IORING_OP_URING_CMD)
+ */
+int fuse_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
+{
+ struct fuse_dev *fud;
+ struct fuse_conn *fc;
+ u32 cmd_op = cmd->cmd_op;
+ int err;
+
+ /* Disabled for now, especially as teardown is not implemented yet */
+ pr_info_ratelimited("fuse-io-uring is not enabled yet\n");
+ return -EOPNOTSUPP;
Do compilers give warnings about such things? Unreachable code, maybe.
I don't care much, but if they do to avoid breaking CONFIG_WERROR you
might want to do sth about it. E.g. I'd usually mark the function
__maybe_unused and not set it into fops until a later patch.
...
--
Pavel Begunkov
