[PATCH v2 1/7] swap: Add comments to lock_cluster_or_swap_info()

From: "Huang, Ying" <ying.huang@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Michal Hocko <mhocko@suse.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Shaohua Li <shli@kernel.org>, Hugh Dickins <hughd@google.com>,
	Minchan Kim <minchan@kernel.org>, Rik van Riel <riel@redhat.com>,
	Daniel Jordan <daniel.m.jordan@oracle.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>
Subject: [PATCH v2 1/7] swap: Add comments to lock_cluster_or_swap_info()
Date: Tue, 17 Jul 2018 08:55:50 +0800	[thread overview]
Message-ID: <20180717005556.29758-2-ying.huang@intel.com> (raw)
In-Reply-To: <20180717005556.29758-1-ying.huang@intel.com>

To improve the code readability.

Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shaohua Li <shli@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
---
 mm/swapfile.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index d8fddfb000ec..0a2a9643dd78 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -297,6 +297,12 @@ static inline void unlock_cluster(struct swap_cluster_info *ci)
 		spin_unlock(&ci->lock);
 }
 
+/*
+ * For non-HDD swap devices, the fine grained cluster lock is used to
+ * protect si->swap_map.  But cluster and cluster locks isn't
+ * available for HDD, so coarse grained si->lock will be used instead
+ * for that.
+ */
 static inline struct swap_cluster_info *lock_cluster_or_swap_info(
 	struct swap_info_struct *si,
 	unsigned long offset)
-- 
2.16.4

