fs/writeback: Convert inode_switch_wbs_work_fn to folios

This gets the statistics correct for large folios by modifying the
counters by the number of pages in the folio instead of by 1.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 67f0e88..4f680f8 100644 (file)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -372,7 +372,7 @@ static bool inode_do_switch_wbs(struct inode *inode,
 {
        struct address_space *mapping = inode->i_mapping;
        XA_STATE(xas, &mapping->i_pages, 0);
-       struct page *page;
+       struct folio *folio;
        bool switched = false;
 
        spin_lock(&inode->i_lock);
@@ -389,21 +389,23 @@ static bool inode_do_switch_wbs(struct inode *inode,
 
        /*
         * Count and transfer stats.  Note that PAGECACHE_TAG_DIRTY points
-        * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to
-        * pages actually under writeback.
+        * to possibly dirty folios while PAGECACHE_TAG_WRITEBACK points to
+        * folios actually under writeback.
         */
-       xas_for_each_marked(&xas, page, ULONG_MAX, PAGECACHE_TAG_DIRTY) {
-               if (PageDirty(page)) {
-                       dec_wb_stat(old_wb, WB_RECLAIMABLE);
-                       inc_wb_stat(new_wb, WB_RECLAIMABLE);
+       xas_for_each_marked(&xas, folio, ULONG_MAX, PAGECACHE_TAG_DIRTY) {
+               if (folio_test_dirty(folio)) {
+                       long nr = folio_nr_pages(folio);
+                       wb_stat_mod(old_wb, WB_RECLAIMABLE, -nr);
+                       wb_stat_mod(new_wb, WB_RECLAIMABLE, nr);
                }
        }
 
        xas_set(&xas, 0);
-       xas_for_each_marked(&xas, page, ULONG_MAX, PAGECACHE_TAG_WRITEBACK) {
-               WARN_ON_ONCE(!PageWriteback(page));
-               dec_wb_stat(old_wb, WB_WRITEBACK);
-               inc_wb_stat(new_wb, WB_WRITEBACK);
+       xas_for_each_marked(&xas, folio, ULONG_MAX, PAGECACHE_TAG_WRITEBACK) {
+               long nr = folio_nr_pages(folio);
+               WARN_ON_ONCE(!folio_test_writeback(folio));
+               wb_stat_mod(old_wb, WB_WRITEBACK, -nr);
+               wb_stat_mod(new_wb, WB_WRITEBACK, nr);
        }
 
        if (mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) {