[PATCH v4 7/8] swap: Add __swap_entry_free_locked()

[Huang Ying]

The part of __swap_entry_free() with lock held is separated into a new
function __swap_entry_free_locked().  Because we want to reuse that
piece of code in some other places.

Just mechanical code refactoring, there is no any functional change in
this function.

Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Reviewed-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Shaohua Li <shli@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
---
 mm/swapfile.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index d80567dd60db..402d52ff3e4a 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1182,16 +1182,13 @@ struct swap_info_struct *get_swap_device(swp_entry_t entry)
 	return NULL;
 }
 
-static unsigned char __swap_entry_free(struct swap_info_struct *p,
-				       swp_entry_t entry, unsigned char usage)
+static unsigned char __swap_entry_free_locked(struct swap_info_struct *p,
+					      unsigned long offset,
+					      unsigned char usage)
 {
-	struct swap_cluster_info *ci;
-	unsigned long offset = swp_offset(entry);
 	unsigned char count;
 	unsigned char has_cache;
 
-	ci = lock_cluster_or_swap_info(p, offset);
-
 	count = p->swap_map[offset];
 
 	has_cache = count & SWAP_HAS_CACHE;
@@ -1219,6 +1216,17 @@ static unsigned char __swap_entry_free(struct swap_info_struct *p,
 	usage = count | has_cache;
 	p->swap_map[offset] = usage ? : SWAP_HAS_CACHE;
 
+	return usage;
+}
+
+static unsigned char __swap_entry_free(struct swap_info_struct *p,
+				       swp_entry_t entry, unsigned char usage)
+{
+	struct swap_cluster_info *ci;
+	unsigned long offset = swp_offset(entry);
+
+	ci = lock_cluster_or_swap_info(p, offset);
+	usage = __swap_entry_free_locked(p, offset, usage);
 	unlock_cluster_or_swap_info(p, ci);
 
 	return usage;
-- 
2.16.4