linux-kernel - [PATCH RFC 5/6] dcache: push releasing dentry lock into sweep

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Date:   Thu, 21 Jan 2021 18:49:44 +0530
From:   Gautham Ananthakrishna <gautham.ananthakrishna@...cle.com>
To:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org
Cc:     viro@...iv.linux.org.uk, matthew.wilcox@...cle.com,
        khlebnikov@...dex-team.ru, gautham.ananthakrishna@...cle.com
Subject: [PATCH RFC 5/6] dcache: push releasing dentry lock into sweep_negative

From: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>

Release the dentry lock inside the sweep_negative() function.  This
is in preparation for a follow up patch and doesn't change runtime
behavior.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Signed-off-by: Gautham Ananthakrisha <gautham.ananthakrishna@...cle.com>
---
 fs/dcache.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 492a42f..22c990b 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -638,13 +638,14 @@ static inline struct dentry *lock_parent(struct dentry *dentry)
  * Must be called at dput of negative dentry.
  */
 static void sweep_negative(struct dentry *dentry)
+	__releases(dentry->d_lock)
 {
 	struct dentry *parent;
 
 	if (!d_is_tail_negative(dentry)) {
 		parent = lock_parent(dentry);
 		if (!parent)
-			return;
+			goto out;
 
 		if (!d_count(dentry) && d_is_negative(dentry) &&
 		    !d_is_tail_negative(dentry)) {
@@ -654,6 +655,8 @@ static void sweep_negative(struct dentry *dentry)
 
 		spin_unlock(&parent->d_lock);
 	}
+out:
+	spin_unlock(&dentry->d_lock);
 }
 
 /*
@@ -922,7 +925,8 @@ void dput(struct dentry *dentry)
 		if (likely(retain_dentry(dentry))) {
 			if (d_is_negative(dentry))
 				sweep_negative(dentry);
-			spin_unlock(&dentry->d_lock);
+			else
+				spin_unlock(&dentry->d_lock);
 			return;
 		}
 
-- 
1.8.3.1