[PATCH 5/7] mm: stop passing a writeback_control structure to swap_writeout

[Christoph Hellwig <hch@xxxxxx>]

swap_writeout only needs the swap_iocb cookie from the writeback_control
structure, so pass it explicitly.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 include/linux/writeback.h |  7 -------
 mm/page_io.c              |  4 ++--
 mm/shmem.c                | 10 +---------
 mm/swap.h                 |  4 +++-
 mm/vmscan.c               | 10 +---------
 5 files changed, 7 insertions(+), 28 deletions(-)

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 82f217970092..9e960f2faf79 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -72,13 +72,6 @@ struct writeback_control {
 	 */
 	unsigned no_cgroup_owner:1;
 
-	/* To enable batching of swap writes to non-block-device backends,
-	 * "plug" can be set point to a 'struct swap_iocb *'.  When all swap
-	 * writes have been submitted, if with swap_iocb is not NULL,
-	 * swap_write_unplug() should be called.
-	 */
-	struct swap_iocb **swap_plug;
-
 	/* internal fields used by the ->writepages implementation: */
 	struct folio_batch fbatch;
 	pgoff_t index;
diff --git a/mm/page_io.c b/mm/page_io.c
index fb52bedcc966..a2056a5ecb13 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -237,7 +237,7 @@ static void swap_zeromap_folio_clear(struct folio *folio)
  * We may have stale swap cache pages in memory: notice
  * them here and get rid of the unnecessary final write.
  */
-int swap_writeout(struct folio *folio, struct writeback_control *wbc)
+int swap_writeout(struct folio *folio, struct swap_iocb **swap_plug)
 {
 	int ret = 0;
 
@@ -281,7 +281,7 @@ int swap_writeout(struct folio *folio, struct writeback_control *wbc)
 		return AOP_WRITEPAGE_ACTIVATE;
 	}
 
-	__swap_writepage(folio, wbc->swap_plug);
+	__swap_writepage(folio, swap_plug);
 	return 0;
 out_unlock:
 	folio_unlock(folio);
diff --git a/mm/shmem.c b/mm/shmem.c
index 941b9b29e78a..2033d2e3d35d 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1635,21 +1635,13 @@ int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
 		list_add(&info->swaplist, &shmem_swaplist);
 
 	if (!folio_alloc_swap(folio, __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN)) {
-		struct writeback_control wbc = {
-			.sync_mode	= WB_SYNC_NONE,
-			.nr_to_write	= SWAP_CLUSTER_MAX,
-			.range_start	= 0,
-			.range_end	= LLONG_MAX,
-			.for_reclaim	= 1,
-			.swap_plug	= plug,
-		};
 		shmem_recalc_inode(inode, 0, nr_pages);
 		swap_shmem_alloc(folio->swap, nr_pages);
 		shmem_delete_from_page_cache(folio, swp_to_radix_entry(folio->swap));
 
 		mutex_unlock(&shmem_swaplist_mutex);
 		BUG_ON(folio_mapped(folio));
-		return swap_writeout(folio, &wbc);
+		return swap_writeout(folio, plug);
 	}
 
 	list_del_init(&info->swaplist);
diff --git a/mm/swap.h b/mm/swap.h
index bd642078544a..c6d661fa9db7 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -3,6 +3,8 @@
 #define _MM_SWAP_H
 
 struct mempolicy;
+struct swap_iocb;
+
 extern int page_cluster;
 
 #ifdef CONFIG_SWAP
@@ -20,7 +22,7 @@ static inline void swap_read_unplug(struct swap_iocb *plug)
 		__swap_read_unplug(plug);
 }
 void swap_write_unplug(struct swap_iocb *sio);
-int swap_writeout(struct folio *folio, struct writeback_control *wbc);
+int swap_writeout(struct folio *folio, struct swap_iocb **swap_plug);
 void __swap_writepage(struct folio *folio, struct swap_iocb **swap_plug);
 
 /* linux/mm/swap_state.c */
diff --git a/mm/vmscan.c b/mm/vmscan.c
index fea78f01d04e..ad89b36eba01 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -655,14 +655,6 @@ typedef enum {
 static pageout_t writeout(struct folio *folio, struct address_space *mapping,
 		struct swap_iocb **plug, struct list_head *folio_list)
 {
-	struct writeback_control wbc = {
-		.sync_mode = WB_SYNC_NONE,
-		.nr_to_write = SWAP_CLUSTER_MAX,
-		.range_start = 0,
-		.range_end = LLONG_MAX,
-		.for_reclaim = 1,
-		.swap_plug = plug,
-	};
 	int res;
 
 	folio_set_reclaim(folio);
@@ -675,7 +667,7 @@ static pageout_t writeout(struct folio *folio, struct address_space *mapping,
 	if (shmem_mapping(mapping))
 		res = shmem_writeout(folio, plug, folio_list);
 	else
-		res = swap_writeout(folio, &wbc);
+		res = swap_writeout(folio, plug);
 
 	if (res < 0)
 		handle_write_error(mapping, folio, res);
-- 
2.47.2