linux-kernel - [PATCH] vfs: make evict() use smp_mb__after_spinlock instead of smp

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Message-ID: <20241113155103.4194099-1-mjguzik@gmail.com>
Date: Wed, 13 Nov 2024 16:51:03 +0100
From: Mateusz Guzik <mjguzik@...il.com>
To: brauner@...nel.org
Cc: viro@...iv.linux.org.uk,
	jack@...e.cz,
	jlayton@...nel.org,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	Mateusz Guzik <mjguzik@...il.com>
Subject: [PATCH] vfs: make evict() use smp_mb__after_spinlock instead of smp_mb

It literally directly follows a spin_lock() call.

This whacks an explicit barrier on x86-64.

Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
---

This plausibly can go away altogether, but I could not be arsed to
convince myself that's correct. Individuals willing to put in time are
welcome :)

 fs/inode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/inode.c b/fs/inode.c
index e5a60084a7a9..b3db1234737f 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -817,7 +817,7 @@ static void evict(struct inode *inode)
 	 * ___wait_var_event() either sees the bit cleared or
 	 * waitqueue_active() check in wake_up_var() sees the waiter.
 	 */
-	smp_mb();
+	smp_mb__after_spinlock();
 	inode_wake_up_bit(inode, __I_NEW);
 	BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
 	spin_unlock(&inode->i_lock);
-- 
2.43.0