From bf9c2f1cdcc718b6d2d41172f6ca005fe22cc7ff Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Sun, 12 Apr 2020 02:05:02 +0300
Subject: [PATCH] io_uring: track mm through current->mm
As a preparation for extracting request init bits, remove self-coded mm
tracking from io_submit_sqes(), but rely on current->mm. It's more
convenient, than passing this piece of state in other functions.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
fs/io_uring.c | 37 ++++++++++++++++---------------------
1 file changed, 16 insertions(+), 21 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 81532479c857be..f7825d3de4008e 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5812,8 +5812,7 @@ static void io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
}
static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
- struct file *ring_file, int ring_fd,
- struct mm_struct **mm, bool async)
+ struct file *ring_file, int ring_fd, bool async)
{
struct io_submit_state state, *statep = NULL;
struct io_kiocb *link = NULL;
@@ -5870,13 +5869,12 @@ fail_req:
break;
}
- if (io_op_defs[req->opcode].needs_mm && !*mm) {
+ if (io_op_defs[req->opcode].needs_mm && !current->mm) {
if (unlikely(!mmget_not_zero(ctx->sqo_mm))) {
err = -EFAULT;
goto fail_req;
}
use_mm(ctx->sqo_mm);
- *mm = ctx->sqo_mm;
}
req->needs_fixed_file = async;
@@ -5902,10 +5900,19 @@ fail_req:
return submitted;
}
+static inline void io_sq_thread_drop_mm(struct io_ring_ctx *ctx)
+{
+ struct mm_struct *mm = current->mm;
+
+ if (mm) {
+ unuse_mm(mm);
+ mmput(mm);
+ }
+}
+
static int io_sq_thread(void *data)
{
struct io_ring_ctx *ctx = data;
- struct mm_struct *cur_mm = NULL;
const struct cred *old_cred;
mm_segment_t old_fs;
DEFINE_WAIT(wait);
@@ -5946,11 +5953,7 @@ static int io_sq_thread(void *data)
* adding ourselves to the waitqueue, as the unuse/drop
* may sleep.
*/
- if (cur_mm) {
- unuse_mm(cur_mm);
- mmput(cur_mm);
- cur_mm = NULL;
- }
+ io_sq_thread_drop_mm(ctx);
/*
* We're polling. If we're within the defined idle
@@ -6014,7 +6017,7 @@ static int io_sq_thread(void *data)
}
mutex_lock(&ctx->uring_lock);
- ret = io_submit_sqes(ctx, to_submit, NULL, -1, &cur_mm, true);
+ ret = io_submit_sqes(ctx, to_submit, NULL, -1, true);
mutex_unlock(&ctx->uring_lock);
timeout = jiffies + ctx->sq_thread_idle;
}
@@ -6023,10 +6026,7 @@ static int io_sq_thread(void *data)
task_work_run();
set_fs(old_fs);
- if (cur_mm) {
- unuse_mm(cur_mm);
- mmput(cur_mm);
- }
+ io_sq_thread_drop_mm(ctx);
revert_creds(old_cred);
kthread_parkme();
@@ -7507,13 +7507,8 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
wake_up(&ctx->sqo_wait);
submitted = to_submit;
} else if (to_submit) {
- struct mm_struct *cur_mm;
-
mutex_lock(&ctx->uring_lock);
- /* already have mm, so io_submit_sqes() won't try to grab it */
- cur_mm = ctx->sqo_mm;
- submitted = io_submit_sqes(ctx, to_submit, f.file, fd,
- &cur_mm, false);
+ submitted = io_submit_sqes(ctx, to_submit, f.file, fd, false);
mutex_unlock(&ctx->uring_lock);
if (submitted != to_submit)
--
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