[PATCH v3 2/3] mm, swap: reduce indention for hibernate allocation helper

[Kairui Song via B4 Relay <devnull+kasong.tencent.com@kernel.org>]

From: Kairui Song <kasong@tencent.com>

It doesn't have to check the device flag, as the allocator will also
check the device flag and refuse to allocate if the device is not
writable. This might cause a trivial waste of CPU cycles of hibernate
allocation raced with swapoff, but that is very unlikely to happen.
Removing the check on the common path should be more helpful.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
 mm/swapfile.c | 38 ++++++++++++++++++--------------------
 1 file changed, 18 insertions(+), 20 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 32e0e7545ab8..0d1b17c99221 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1936,27 +1936,25 @@ swp_entry_t swap_alloc_hibernation_slot(int type)
 
 	/* This is called for allocating swap entry, not cache */
 	if (get_swap_device_info(si)) {
-		if (si->flags & SWP_WRITEOK) {
-			/*
-			 * Try the local cluster first if it matches the device. If
-			 * not, try grab a new cluster and override local cluster.
-			 */
-			local_lock(&percpu_swap_cluster.lock);
-			pcp_si = this_cpu_read(percpu_swap_cluster.si[0]);
-			pcp_offset = this_cpu_read(percpu_swap_cluster.offset[0]);
-			if (pcp_si == si && pcp_offset) {
-				ci = swap_cluster_lock(si, pcp_offset);
-				if (cluster_is_usable(ci, 0))
-					offset = alloc_swap_scan_cluster(si, ci, NULL, pcp_offset);
-				else
-					swap_cluster_unlock(ci);
-			}
-			if (!offset)
-				offset = cluster_alloc_swap_entry(si, NULL);
-			local_unlock(&percpu_swap_cluster.lock);
-			if (offset)
-				entry = swp_entry(si->type, offset);
+		/*
+		 * Try the local cluster first if it matches the device. If
+		 * not, try grab a new cluster and override local cluster.
+		 */
+		local_lock(&percpu_swap_cluster.lock);
+		pcp_si = this_cpu_read(percpu_swap_cluster.si[0]);
+		pcp_offset = this_cpu_read(percpu_swap_cluster.offset[0]);
+		if (pcp_si == si && pcp_offset) {
+			ci = swap_cluster_lock(si, pcp_offset);
+			if (cluster_is_usable(ci, 0))
+				offset = alloc_swap_scan_cluster(si, ci, NULL, pcp_offset);
+			else
+				swap_cluster_unlock(ci);
 		}
+		if (!offset)
+			offset = cluster_alloc_swap_entry(si, NULL);
+		local_unlock(&percpu_swap_cluster.lock);
+		if (offset)
+			entry = swp_entry(si->type, offset);
 		put_swap_device(si);
 	}
 fail:

-- 
2.52.0