linux-kernel - [PATCH 1/2] fs/aio: Use kmap

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Message-Id: <20230118152603.28301-1-kent.overstreet@linux.dev>
Date:   Wed, 18 Jan 2023 10:26:02 -0500
From:   Kent Overstreet <kent.overstreet@...ux.dev>
To:     linux-kernel@...r.kernel.org
Cc:     Kent Overstreet <kent.overstreet@...ux.dev>, linux-aio@...ck.org,
        linux-fsdevel@...r.kernel.org
Subject: [PATCH 1/2] fs/aio: Use kmap_local() instead of kmap()

Originally, we used kmap() instead of kmap_atomic() for reading events
out of the completion ringbuffer because we're using copy_to_user(),
which can fault.

Now that kmap_local() is a thing, use that instead.

Signed-off-by: Kent Overstreet <kent.overstreet@...ux.dev>
Cc: Benjamin LaHaise <bcrl@...ck.org
Cc: linux-aio@...ck.org
Cc: linux-fsdevel@...r.kernel.org
---
 fs/aio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 5b2ff20ad3..3f795ed2a2 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1246,10 +1246,10 @@ static long aio_read_events_ring(struct kioctx *ctx,
 		avail = min(avail, nr - ret);
 		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
 
-		ev = kmap(page);
+		ev = kmap_local_page(page);
 		copy_ret = copy_to_user(event + ret, ev + pos,
 					sizeof(*ev) * avail);
-		kunmap(page);
+		kunmap_local(ev);
 
 		if (unlikely(copy_ret)) {
 			ret = -EFAULT;
-- 
2.39.0