mm/swapfile.c: clear si->swap_map[] in swap_free_cluster()

si->swap_map[] of the swap entries in cluster needs to be cleared during
freeing.  Previously, this is done in the caller of swap_free_cluster().
This may cause code duplication (one user now, will add more users later)
and lock/unlock cluster unnecessarily.  In this patch, the clearing code
is moved to swap_free_cluster() to avoid the downside.

Link: http://lkml.kernel.org/r/20180827075535.17406-4-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: 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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/swapfile.c b/mm/swapfile.c
index eaa5e2e..2681e50 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -932,6 +932,7 @@ static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx)
        struct swap_cluster_info *ci;
 
        ci = lock_cluster(si, offset);
+       memset(si->swap_map + offset, 0, SWAPFILE_CLUSTER);
        cluster_set_count_flag(ci, 0, 0);
        free_cluster(si, idx);
        unlock_cluster(ci);
@@ -1250,9 +1251,6 @@ void put_swap_page(struct page *page, swp_entry_t entry)
                if (free_entries == SWAPFILE_CLUSTER) {
                        unlock_cluster_or_swap_info(si, ci);
                        spin_lock(&si->lock);
-                       ci = lock_cluster(si, offset);
-                       memset(map, 0, SWAPFILE_CLUSTER);
-                       unlock_cluster(ci);
                        mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER);
                        swap_free_cluster(si, idx);
                        spin_unlock(&si->lock);