From a087e2b519929152fdde8299457e32d5a8994a7c Mon Sep 17 00:00:00 2001
From: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Date: Tue, 16 Jun 2020 16:36:07 -0700
Subject: [PATCH] io_uring: add wrappers for memory accounting

Facilitate separation of locked memory usage reporting vs. limiting for
upcoming patches.  No functional changes.

Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
[axboe: kill unnecessary () around return in io_account_mem()]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c | 48 ++++++++++++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 311e8038ae58..9db9f09499d1 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6968,12 +6968,14 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx,
 	return ret;
 }
 
-static void io_unaccount_mem(struct user_struct *user, unsigned long nr_pages)
+static inline void __io_unaccount_mem(struct user_struct *user,
+				      unsigned long nr_pages)
 {
 	atomic_long_sub(nr_pages, &user->locked_vm);
 }
 
-static int io_account_mem(struct user_struct *user, unsigned long nr_pages)
+static inline int __io_account_mem(struct user_struct *user,
+				   unsigned long nr_pages)
 {
 	unsigned long page_limit, cur_pages, new_pages;
 
@@ -6991,6 +6993,20 @@ static int io_account_mem(struct user_struct *user, unsigned long nr_pages)
 	return 0;
 }
 
+static void io_unaccount_mem(struct io_ring_ctx *ctx, unsigned long nr_pages)
+{
+	if (ctx->account_mem)
+		__io_unaccount_mem(ctx->user, nr_pages);
+}
+
+static int io_account_mem(struct io_ring_ctx *ctx, unsigned long nr_pages)
+{
+	if (ctx->account_mem)
+		return __io_account_mem(ctx->user, nr_pages);
+
+	return 0;
+}
+
 static void io_mem_free(void *ptr)
 {
 	struct page *page;
@@ -7065,8 +7081,7 @@ static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx)
 		for (j = 0; j < imu->nr_bvecs; j++)
 			unpin_user_page(imu->bvec[j].bv_page);
 
-		if (ctx->account_mem)
-			io_unaccount_mem(ctx->user, imu->nr_bvecs);
+		io_unaccount_mem(ctx, imu->nr_bvecs);
 		kvfree(imu->bvec);
 		imu->nr_bvecs = 0;
 	}
@@ -7149,11 +7164,9 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
 		start = ubuf >> PAGE_SHIFT;
 		nr_pages = end - start;
 
-		if (ctx->account_mem) {
-			ret = io_account_mem(ctx->user, nr_pages);
-			if (ret)
-				goto err;
-		}
+		ret = io_account_mem(ctx, nr_pages);
+		if (ret)
+			goto err;
 
 		ret = 0;
 		if (!pages || nr_pages > got_pages) {
@@ -7166,8 +7179,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
 					GFP_KERNEL);
 			if (!pages || !vmas) {
 				ret = -ENOMEM;
-				if (ctx->account_mem)
-					io_unaccount_mem(ctx->user, nr_pages);
+				io_unaccount_mem(ctx, nr_pages);
 				goto err;
 			}
 			got_pages = nr_pages;
@@ -7177,8 +7189,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
 						GFP_KERNEL);
 		ret = -ENOMEM;
 		if (!imu->bvec) {
-			if (ctx->account_mem)
-				io_unaccount_mem(ctx->user, nr_pages);
+			io_unaccount_mem(ctx, nr_pages);
 			goto err;
 		}
 
@@ -7209,8 +7220,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
 			 */
 			if (pret > 0)
 				unpin_user_pages(pages, pret);
-			if (ctx->account_mem)
-				io_unaccount_mem(ctx->user, nr_pages);
+			io_unaccount_mem(ctx, nr_pages);
 			kvfree(imu->bvec);
 			goto err;
 		}
@@ -7315,9 +7325,7 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 	io_mem_free(ctx->sq_sqes);
 
 	percpu_ref_exit(&ctx->refs);
-	if (ctx->account_mem)
-		io_unaccount_mem(ctx->user,
-				ring_pages(ctx->sq_entries, ctx->cq_entries));
+	io_unaccount_mem(ctx, ring_pages(ctx->sq_entries, ctx->cq_entries));
 	free_uid(ctx->user);
 	put_cred(ctx->creds);
 	kfree(ctx->cancel_hash);
@@ -7887,7 +7895,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p,
 	account_mem = !capable(CAP_IPC_LOCK);
 
 	if (account_mem) {
-		ret = io_account_mem(user,
+		ret = __io_account_mem(user,
 				ring_pages(p->sq_entries, p->cq_entries));
 		if (ret) {
 			free_uid(user);
@@ -7898,7 +7906,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p,
 	ctx = io_ring_ctx_alloc(p);
 	if (!ctx) {
 		if (account_mem)
-			io_unaccount_mem(user, ring_pages(p->sq_entries,
+			__io_unaccount_mem(user, ring_pages(p->sq_entries,
 								p->cq_entries));
 		free_uid(user);
 		return -ENOMEM;
-- 
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