mm: Extend 'usage' parameter so that cluster_swap_free_nr() can be reused

From: Barry Song <[email protected]>

Extend a usage parameter so that cluster_swap_free_nr() can be reused by both swapcache_clear() and swap_free().
__swap_entry_free() is quite similar but more tricky as it requires the return value of __swap_entry_free_locked() which cluster_swap_free_nr() doesn't support.

Cc "Huang, Ying" <[email protected]>

Cc Chris Li <[email protected]>

Cc Kairui Song <[email protected]>

Cc David Hildenbrand <[email protected]>

Cc Chuanhua Han <[email protected]>

Reviewed-by Ryan Roberts <[email protected]>

Signed-off-by Barry Song <[email protected]>

---
-v3: resend &collect Ryan's reviewed-by

 mm/swapfile.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

mm/swapfile.c +5 -11

index 38bdc439651a..5f73a8553371 100644
@@ -1344,7 +1344,8 @@ static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry)
 }
 
 static void cluster_swap_free_nr(struct swap_info_struct *sis,
-               unsigned long offset, int nr_pages)
+               unsigned long offset, int nr_pages,
+               unsigned char usage)
 {
        struct swap_cluster_info *ci;
        DECLARE_BITMAP(to_free, BITS_PER_LONG) = { 0 };

@@ -1354,7 +1355,7 @@ static void cluster_swap_free_nr(struct swap_info_struct *sis,
        while (nr_pages) {
                nr = min(BITS_PER_LONG, nr_pages);
                for (i = 0; i < nr; i++) {
-                       if (!__swap_entry_free_locked(sis, offset + i, 1))
+                       if (!__swap_entry_free_locked(sis, offset + i, usage))
                                bitmap_set(to_free, i, 1);
                }
                if (!bitmap_empty(to_free, BITS_PER_LONG)) {

@@ -1388,7 +1389,7 @@ void swap_free_nr(swp_entry_t entry, int nr_pages)
 
        while (nr_pages) {
                nr = min_t(int, nr_pages, SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER);
-               cluster_swap_free_nr(sis, offset, nr);
+               cluster_swap_free_nr(sis, offset, nr, 1);
                offset += nr;
                nr_pages -= nr;
        }

@@ -3472,15 +3473,9 @@ int swapcache_prepare(swp_entry_t entry)
 
 void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry)
 {
-       struct swap_cluster_info *ci;
        unsigned long offset = swp_offset(entry);
-       unsigned char usage;
 
-       ci = lock_cluster_or_swap_info(si, offset);
-       usage = __swap_entry_free_locked(si, offset, SWAP_HAS_CACHE);
-       unlock_cluster_or_swap_info(si, ci);
-       if (!usage)
-               free_swap_slot(entry);
+       cluster_swap_free_nr(si, offset, 1, SWAP_HAS_CACHE);
 }
 
 struct swap_info_struct *swp_swap_info(swp_entry_t entry)
--

2.34.1