[PATCH v1 3/9] dentry: Use preempt_[dis|en]able_nested()

[Konstantin Ryabitsev via B4 Web Endpoint <devnull@kernel.org>]

From: Thomas Gleixner <tglx@linutronix.de>

Replace the open coded CONFIG_PREEMPT_RT conditional
preempt_disable/enable() with the new helper.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>

diff --git a/fs/dcache.c b/fs/dcache.c
index c5dc32a59c76..e633b20623d0 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2571,15 +2571,7 @@ EXPORT_SYMBOL(d_rehash);
 
 static inline unsigned start_dir_add(struct inode *dir)
 {
-	/*
-	 * The caller holds a spinlock (dentry::d_lock). On !PREEMPT_RT
-	 * kernels spin_lock() implicitly disables preemption, but not on
-	 * PREEMPT_RT.  So for RT it has to be done explicitly to protect
-	 * the sequence count write side critical section against a reader
-	 * or another writer preempting, which would result in a live lock.
-	 */
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_disable();
+	preempt_disable_nested();
 	for (;;) {
 		unsigned n = dir->i_dir_seq;
 		if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n)
@@ -2592,8 +2584,7 @@ static inline void end_dir_add(struct inode *dir, unsigned int n,
 			       wait_queue_head_t *d_wait)
 {
 	smp_store_release(&dir->i_dir_seq, n + 2);
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_enable();
+	preempt_enable_nested();
 	wake_up_all(d_wait);
 }
 

-- 
b4 0.10.0-dev-c53d8