[PATCH for-next 06/12] io_uring: add fixed file peeking function

Dylan Yudaken
2022-10-31T13:41:55Z

Add a helper function to grab the fixed file at a given offset. Will be
useful for retarget op handlers.

Signed-off-by: Dylan Yudaken <dylany@meta.com>
---
io_uring/io_uring.c | 26 ++++++++++++++++++++------
io_uring/io_uring.h | 1 +
2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 32eb305c4ce7..a052653fc65e 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1841,6 +1841,23 @@ void io_wq_submit_work(struct io_wq_work *work)
io_req_task_queue_fail(req, ret);
}

+static unsigned long __io_file_peek_fixed(struct io_kiocb *req, int fd)
+ __must_hold(&req->ctx->uring_lock)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+
+ if (unlikely((unsigned int)fd >= ctx->nr_user_files))
+ return 0;
+ fd = array_index_nospec(fd, ctx->nr_user_files);
+ return io_fixed_file_slot(&ctx->file_table, fd)->file_ptr;
+}
+
+struct file *io_file_peek_fixed(struct io_kiocb *req, int fd)
+ __must_hold(&req->ctx->uring_lock)
+{
+ return (struct file *) (__io_file_peek_fixed(req, fd) & FFS_MASK);
+}
+
inline struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
unsigned int issue_flags)
{
@@ -1849,17 +1866,14 @@ inline struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
unsigned long file_ptr;

io_ring_submit_lock(ctx, issue_flags);
-
- if (unlikely((unsigned int)fd >= ctx->nr_user_files))
- goto out;
- fd = array_index_nospec(fd, ctx->nr_user_files);
- file_ptr = io_fixed_file_slot(&ctx->file_table, fd)->file_ptr;
+ file_ptr = __io_file_peek_fixed(req, fd);
file = (struct file *) (file_ptr & FFS_MASK);
file_ptr &= ~FFS_MASK;
/* mask in overlapping REQ_F and FFS bits */
req->flags |= (file_ptr << REQ_F_SUPPORT_NOWAIT_BIT);
io_req_set_rsrc_node(req, ctx, 0);
-out:
+ WARN_ON_ONCE(file && !test_bit(fd, ctx->file_table.bitmap));
+
io_ring_submit_unlock(ctx, issue_flags);
return file;
}
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index ef77d2aa3172..781471bfba12 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -44,6 +44,7 @@ struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages);
struct file *io_file_get_normal(struct io_kiocb *req, int fd);
struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
unsigned issue_flags);
+struct file *io_file_peek_fixed(struct io_kiocb *req, int fd);

static inline bool io_req_ffs_set(struct io_kiocb *req)
{
--
2.30.2