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From: Vivek Goyal <vgoyal@redhat.com>
To: linux-fsdevel@vger.kernel.org, dan.j.williams@intel.com,
	jack@suse.cz, willy@infradead.org
Cc: virtio-fs@redhat.com, slp@redhat.com, miklos@szeredi.hu,
	linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org,
	vgoyal@redhat.com
Subject: [PATCH v3 1/3] dax: Add an enum for specifying dax wakup mode
Date: Mon, 19 Apr 2021 17:36:34 -0400
Message-ID: <20210419213636.1514816-2-vgoyal@redhat.com> (raw)
In-Reply-To: <20210419213636.1514816-1-vgoyal@redhat.com>

Dan mentioned that he is not very fond of passing around a boolean true/false
to specify if only next waiter should be woken up or all waiters should be
woken up. He instead prefers that we introduce an enum and make it very
explicity at the callsite itself. Easier to read code.

This patch should not introduce any change of behavior.

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 fs/dax.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index b3d27fdc6775..00978d0838b1 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -144,6 +144,16 @@ struct wait_exceptional_entry_queue {
 	struct exceptional_entry_key key;
 };
 
+/**
+ * enum dax_entry_wake_mode: waitqueue wakeup toggle
+ * @WAKE_NEXT: entry was not mutated
+ * @WAKE_ALL: entry was invalidated, or resized
+ */
+enum dax_entry_wake_mode {
+	WAKE_NEXT,
+	WAKE_ALL,
+};
+
 static wait_queue_head_t *dax_entry_waitqueue(struct xa_state *xas,
 		void *entry, struct exceptional_entry_key *key)
 {
@@ -182,7 +192,8 @@ static int wake_exceptional_entry_func(wait_queue_entry_t *wait,
  * The important information it's conveying is whether the entry at
  * this index used to be a PMD entry.
  */
-static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
+static void dax_wake_entry(struct xa_state *xas, void *entry,
+			   enum dax_entry_wake_mode mode)
 {
 	struct exceptional_entry_key key;
 	wait_queue_head_t *wq;
@@ -196,7 +207,7 @@ static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
 	 * must be in the waitqueue and the following check will see them.
 	 */
 	if (waitqueue_active(wq))
-		__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
+		__wake_up(wq, TASK_NORMAL, mode == WAKE_ALL ? 0 : 1, &key);
 }
 
 /*
@@ -268,7 +279,7 @@ static void put_unlocked_entry(struct xa_state *xas, void *entry)
 {
 	/* If we were the only waiter woken, wake the next one */
 	if (entry && !dax_is_conflict(entry))
-		dax_wake_entry(xas, entry, false);
+		dax_wake_entry(xas, entry, WAKE_NEXT);
 }
 
 /*
@@ -286,7 +297,7 @@ static void dax_unlock_entry(struct xa_state *xas, void *entry)
 	old = xas_store(xas, entry);
 	xas_unlock_irq(xas);
 	BUG_ON(!dax_is_locked(old));
-	dax_wake_entry(xas, entry, false);
+	dax_wake_entry(xas, entry, WAKE_NEXT);
 }
 
 /*
@@ -524,7 +535,7 @@ static void *grab_mapping_entry(struct xa_state *xas,
 
 		dax_disassociate_entry(entry, mapping, false);
 		xas_store(xas, NULL);	/* undo the PMD join */
-		dax_wake_entry(xas, entry, true);
+		dax_wake_entry(xas, entry, WAKE_ALL);
 		mapping->nrexceptional--;
 		entry = NULL;
 		xas_set(xas, index);
@@ -937,7 +948,7 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev,
 	xas_lock_irq(xas);
 	xas_store(xas, entry);
 	xas_clear_mark(xas, PAGECACHE_TAG_DIRTY);
-	dax_wake_entry(xas, entry, false);
+	dax_wake_entry(xas, entry, WAKE_NEXT);
 
 	trace_dax_writeback_one(mapping->host, index, count);
 	return ret;
-- 
2.25.4


  reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-19 21:36 [PATCH v3 0/3] dax: Fix missed wakeup in put_unlocked_entry() Vivek Goyal
2021-04-19 21:36 ` Vivek Goyal [this message]
2021-04-20  7:19   ` [Virtio-fs] [PATCH v3 1/3] dax: Add an enum for specifying dax wakup mode Greg Kurz
2021-04-21  9:24   ` Jan Kara
2021-04-21 15:56     ` Vivek Goyal
2021-04-21 16:16       ` Matthew Wilcox
2021-04-21 17:21         ` Vivek Goyal
2021-04-19 21:36 ` [PATCH v3 2/3] dax: Add a wakeup mode parameter to put_unlocked_entry() Vivek Goyal
2021-04-20  7:34   ` [Virtio-fs] " Greg Kurz
2021-04-20 14:00     ` Vivek Goyal
2021-04-21 19:09       ` Dan Williams
2021-04-21 19:13         ` Vivek Goyal
2021-04-22  6:24         ` Christoph Hellwig
2021-04-22 16:12           ` Darrick J. Wong
2021-04-22 20:01           ` Dan Williams
2021-04-22 20:07             ` Vivek Goyal
2021-05-17 17:10           ` Dan Williams
2021-04-21 17:39     ` Vivek Goyal
2021-04-21  9:25   ` Jan Kara
2021-04-19 21:36 ` [PATCH v3 3/3] dax: Wake up all waiters after invalidating dax entry Vivek Goyal
2021-04-21  9:26   ` Jan Kara

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