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authorPavel Begunkov <asml.silence@gmail.com>2021-08-10 14:52:47 +0100
committerJens Axboe <axboe@kernel.dk>2021-08-11 16:35:57 -0600
commitff49e5982f3d9d86c4846d0304eec82831514418 (patch)
tree641c1a6a7f571f87f0cbc0905ed18195a77be915
parent8de254e05555fab96226be5bd062f131df14d9e0 (diff)
io_uring: remove file batch-get optimisation
For requests with non-fixed files, instead of grabbing just one reference, we get by the number of left requests, so the following requests using the same file can take it without atomics. However, it's not all win. If there is one request in the middle not using files or having a fixed file, we'll need to put back the left references. Even worse if an application submits requests dealing with different files, it will do a put for each new request, so doubling the number of atomics needed. Also, even if not used, it's still takes some cycles in the submission path. If a file used many times, it rather makes sense to pre-register it, if not, we may fall in the described pitfall. So, this optimisation is a matter of use case. Go with the simpliest code-wise way, remove it. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/io_uring.c53
1 files changed, 4 insertions, 49 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 592b9d7a0dda..75e5840f4d23 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -324,12 +324,6 @@ struct io_submit_state {
/* inline/task_work completion list, under ->uring_lock */
struct list_head free_list;
- /*
- * File reference cache
- */
- struct file *file;
- unsigned int fd;
- unsigned int file_refs;
unsigned int ios_left;
};
@@ -1052,7 +1046,6 @@ static int __io_register_rsrc_update(struct io_ring_ctx *ctx, unsigned type,
unsigned nr_args);
static void io_clean_op(struct io_kiocb *req);
static struct file *io_file_get(struct io_ring_ctx *ctx,
- struct io_submit_state *state,
struct io_kiocb *req, int fd, bool fixed);
static void __io_queue_sqe(struct io_kiocb *req);
static void io_rsrc_put_work(struct work_struct *work);
@@ -2581,40 +2574,6 @@ static void io_iopoll_req_issued(struct io_kiocb *req)
}
}
-static inline void io_state_file_put(struct io_submit_state *state)
-{
- if (state->file_refs) {
- fput_many(state->file, state->file_refs);
- state->file_refs = 0;
- }
-}
-
-/*
- * Get as many references to a file as we have IOs left in this submission,
- * assuming most submissions are for one file, or at least that each file
- * has more than one submission.
- */
-static struct file *__io_file_get(struct io_submit_state *state, int fd)
-{
- if (!state)
- return fget(fd);
-
- if (state->file_refs) {
- if (state->fd == fd) {
- state->file_refs--;
- return state->file;
- }
- io_state_file_put(state);
- }
- state->file = fget_many(fd, state->ios_left);
- if (unlikely(!state->file))
- return NULL;
-
- state->fd = fd;
- state->file_refs = state->ios_left - 1;
- return state->file;
-}
-
static bool io_bdev_nowait(struct block_device *bdev)
{
return !bdev || blk_queue_nowait(bdev_get_queue(bdev));
@@ -3616,8 +3575,7 @@ static int __io_splice_prep(struct io_kiocb *req,
if (unlikely(sp->flags & ~valid_flags))
return -EINVAL;
- sp->file_in = io_file_get(req->ctx, NULL, req,
- READ_ONCE(sqe->splice_fd_in),
+ sp->file_in = io_file_get(req->ctx, req, READ_ONCE(sqe->splice_fd_in),
(sp->flags & SPLICE_F_FD_IN_FIXED));
if (!sp->file_in)
return -EBADF;
@@ -6354,10 +6312,9 @@ static inline struct file *io_file_get_fixed(struct io_ring_ctx *ctx,
}
static struct file *io_file_get_normal(struct io_ring_ctx *ctx,
- struct io_submit_state *state,
struct io_kiocb *req, int fd)
{
- struct file *file = __io_file_get(state, fd);
+ struct file *file = fget(fd);
trace_io_uring_file_get(ctx, fd);
@@ -6368,13 +6325,12 @@ static struct file *io_file_get_normal(struct io_ring_ctx *ctx,
}
static inline struct file *io_file_get(struct io_ring_ctx *ctx,
- struct io_submit_state *state,
struct io_kiocb *req, int fd, bool fixed)
{
if (fixed)
return io_file_get_fixed(ctx, req, fd);
else
- return io_file_get_normal(ctx, state, req, fd);
+ return io_file_get_normal(ctx, req, fd);
}
static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
@@ -6587,7 +6543,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
}
if (io_op_defs[req->opcode].needs_file) {
- req->file = io_file_get(ctx, state, req, READ_ONCE(sqe->fd),
+ req->file = io_file_get(ctx, req, READ_ONCE(sqe->fd),
(sqe_flags & IOSQE_FIXED_FILE));
if (unlikely(!req->file))
ret = -EBADF;
@@ -6672,7 +6628,6 @@ static void io_submit_state_end(struct io_submit_state *state,
io_submit_flush_completions(ctx);
if (state->plug_started)
blk_finish_plug(&state->plug);
- io_state_file_put(state);
}
/*