On Tue, Nov 26, 2024 at 03:45:09PM +0000, Pavel Begunkov wrote:
> On 11/26/24 13:54, Anuj Gupta wrote:
> > On Tue, Nov 26, 2024 at 01:01:03PM +0000, Pavel Begunkov wrote:
> > > On 11/25/24 07:06, Anuj Gupta wrote:
>
> Hmm, I have doubts it's going to work well because the union
> members have different sizes. Adding a new type could grow
> struct io_uring_attr, which is already bad for uapi. And it
> can't be stacked:
>
How about something like this [1]. I have removed the io_uring_attr
structure, and with the mask scheme the user would pass attributes in
order of their types. Do you still see some cracks?
[1]
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index aac9a4f8fa9a..38f0d6b10eaf 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -98,6 +98,10 @@ struct io_uring_sqe {
__u64 addr3;
__u64 __pad2[1];
};
+ struct {
+ __u64 attr_ptr; /* pointer to attribute information */
+ __u64 attr_type_mask; /* bit mask of attributes */
+ };
__u64 optval;
/*
* If the ring is initialized with IORING_SETUP_SQE128, then
@@ -107,6 +111,18 @@ struct io_uring_sqe {
};
};
+/* sqe->attr_type_mask flags */
+#define IORING_RW_ATTR_FLAG_PI (1U << 0)
+/* PI attribute information */
+struct io_uring_attr_pi {
+ __u16 flags;
+ __u16 app_tag;
+ __u32 len;
+ __u64 addr;
+ __u64 seed;
+ __u64 rsvd;
+};
+
/*
* If sqe->file_index is set to this for opcodes that instantiate a new
* direct descriptor (like openat/openat2/accept), then io_uring will allocate
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index c3a7d0197636..02291ea679fb 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3889,6 +3889,8 @@ static int __init io_uring_init(void)
BUILD_BUG_SQE_ELEM(46, __u16, __pad3[0]);
BUILD_BUG_SQE_ELEM(48, __u64, addr3);
BUILD_BUG_SQE_ELEM_SIZE(48, 0, cmd);
+ BUILD_BUG_SQE_ELEM(48, __u64, attr_ptr);
+ BUILD_BUG_SQE_ELEM(56, __u64, attr_type_mask);
BUILD_BUG_SQE_ELEM(56, __u64, __pad2);
BUILD_BUG_ON(sizeof(struct io_uring_files_update) !=
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 0bcb83e4ce3c..8d2ec89fd76b 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -257,11 +257,53 @@ static int io_prep_rw_setup(struct io_kiocb *req, int ddir, bool do_import)
return 0;
}
+static inline void io_meta_save_state(struct io_async_rw *io)
+{
+ io->meta_state.seed = io->meta.seed;
+ iov_iter_save_state(&io->meta.iter, &io->meta_state.iter_meta);
+}
+
+static inline void io_meta_restore(struct io_async_rw *io, struct kiocb *kiocb)
+{
+ if (kiocb->ki_flags & IOCB_HAS_METADATA) {
+ io->meta.seed = io->meta_state.seed;
+ iov_iter_restore(&io->meta.iter, &io->meta_state.iter_meta);
+ }
+}
+
+static int io_prep_rw_pi(struct io_kiocb *req, struct io_rw *rw, int ddir,
+ u64 attr_ptr, u64 attr_type_mask)
+{
+ struct io_uring_attr_pi pi_attr;
+ struct io_async_rw *io;
+ int ret;
+
+ if (copy_from_user(&pi_attr, u64_to_user_ptr(attr_ptr),
+ sizeof(pi_attr)))
+ return -EFAULT;
+
+ if (pi_attr.rsvd)
+ return -EINVAL;
+
+ io = req->async_data;
+ io->meta.flags = pi_attr.flags;
+ io->meta.app_tag = pi_attr.app_tag;
+ io->meta.seed = READ_ONCE(pi_attr.seed);
+ ret = import_ubuf(ddir, u64_to_user_ptr(pi_attr.addr),
+ pi_attr.len, &io->meta.iter);
+ if (unlikely(ret < 0))
+ return ret;
+ rw->kiocb.ki_flags |= IOCB_HAS_METADATA;
+ io_meta_save_state(io);
+ return ret;
+}
+
static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
int ddir, bool do_import)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
unsigned ioprio;
+ u64 attr_type_mask;
int ret;
rw->kiocb.ki_pos = READ_ONCE(sqe->off);
@@ -279,11 +321,28 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
rw->kiocb.ki_ioprio = get_current_ioprio();
}
rw->kiocb.dio_complete = NULL;
+ rw->kiocb.ki_flags = 0;
rw->addr = READ_ONCE(sqe->addr);
rw->len = READ_ONCE(sqe->len);
rw->flags = READ_ONCE(sqe->rw_flags);
- return io_prep_rw_setup(req, ddir, do_import);
+ ret = io_prep_rw_setup(req, ddir, do_import);
+
+ if (unlikely(ret))
+ return ret;
+
+ attr_type_mask = READ_ONCE(sqe->attr_type_mask);
+ if (attr_type_mask) {
+ u64 attr_ptr;
+
+ /* only PI attribute is supported currently */
+ if (attr_type_mask != IORING_RW_ATTR_FLAG_PI)
+ return -EINVAL;
+
+ attr_ptr = READ_ONCE(sqe->attr_ptr);
+ ret = io_prep_rw_pi(req, rw, ddir, attr_ptr, attr_type_mask);
+ }
+ return ret;
}
int io_prep_read(struct io_kiocb *req, const struct io_uring_sqe *sqe)
@@ -409,7 +468,9 @@ static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req)
static void io_resubmit_prep(struct io_kiocb *req)
{
struct io_async_rw *io = req->async_data;
+ struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
+ io_meta_restore(io, &rw->kiocb);
iov_iter_restore(&io->iter, &io->iter_state);
}
@@ -744,6 +805,10 @@ static bool io_rw_should_retry(struct io_kiocb *req)
if (kiocb->ki_flags & (IOCB_DIRECT | IOCB_HIPRI))
return false;
+ /* never retry for meta io */
+ if (kiocb->ki_flags & IOCB_HAS_METADATA)
+ return false;
+
/*
* just use poll if we can, and don't attempt if the fs doesn't
* support callback based unlocks
@@ -794,7 +859,7 @@ static int io_rw_init_file(struct io_kiocb *req, fmode_t mode, int rw_type)
if (!(req->flags & REQ_F_FIXED_FILE))
req->flags |= io_file_get_flags(file);
- kiocb->ki_flags = file->f_iocb_flags;
+ kiocb->ki_flags |= file->f_iocb_flags;
ret = kiocb_set_rw_flags(kiocb, rw->flags, rw_type);
if (unlikely(ret))
return ret;
@@ -828,6 +893,18 @@ static int io_rw_init_file(struct io_kiocb *req, fmode_t mode, int rw_type)
kiocb->ki_complete = io_complete_rw;
}
+ if (kiocb->ki_flags & IOCB_HAS_METADATA) {
+ struct io_async_rw *io = req->async_data;
+
+ /*
+ * We have a union of meta fields with wpq used for buffered-io
+ * in io_async_rw, so fail it here.
+ */
+ if (!(req->file->f_flags & O_DIRECT))
+ return -EOPNOTSUPP;
+ kiocb->private = &io->meta;
+ }
+
return 0;
}
@@ -902,6 +979,7 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
* manually if we need to.
*/
iov_iter_restore(&io->iter, &io->iter_state);
+ io_meta_restore(io, kiocb);
do {
/*
@@ -1125,6 +1203,7 @@ int io_write(struct io_kiocb *req, unsigned int issue_flags)
} else {
ret_eagain:
iov_iter_restore(&io->iter, &io->iter_state);
+ io_meta_restore(io, kiocb);
if (kiocb->ki_flags & IOCB_WRITE)
io_req_end_write(req);
return -EAGAIN;
diff --git a/io_uring/rw.h b/io_uring/rw.h
index 3f432dc75441..2d7656bd268d 100644
--- a/io_uring/rw.h
+++ b/io_uring/rw.h
@@ -2,6 +2,11 @@
#include <linux/pagemap.h>
+struct io_meta_state {
+ u32 seed;
+ struct iov_iter_state iter_meta;
+};
+
struct io_async_rw {
size_t bytes_done;
struct iov_iter iter;
@@ -9,7 +14,14 @@ struct io_async_rw {
struct iovec fast_iov;
struct iovec *free_iovec;
int free_iov_nr;
- struct wait_page_queue wpq;
+ /* wpq is for buffered io, while meta fields are used with direct io */
+ union {
+ struct wait_page_queue wpq;
+ struct {
+ struct uio_meta meta;
+ struct io_meta_state meta_state;
+ };
+ };
};
int io_prep_read_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe);
--
2.25.1
