[PATCH 6/8] mm/memory-failure: Convert memory_failure() to use a folio

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Saves dozens of calls to compound_head().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/memory-failure.c | 40 +++++++++++++++++++++-------------------
 1 file changed, 21 insertions(+), 19 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index fe4959e994d0..74e87a0a792c 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2189,7 +2189,7 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
 int memory_failure(unsigned long pfn, int flags)
 {
 	struct page *p;
-	struct page *hpage;
+	struct folio *folio;
 	struct dev_pagemap *pgmap;
 	int res = 0;
 	unsigned long page_flags;
@@ -2277,8 +2277,8 @@ int memory_failure(unsigned long pfn, int flags)
 		}
 	}
 
-	hpage = compound_head(p);
-	if (PageTransHuge(hpage)) {
+	folio = page_folio(p);
+	if (folio_test_large(folio)) {
 		/*
 		 * The flag must be set after the refcount is bumped
 		 * otherwise it may race with THP split.
@@ -2292,12 +2292,13 @@ int memory_failure(unsigned long pfn, int flags)
 		 * or unhandlable page.  The refcount is bumped iff the
 		 * page is a valid handlable page.
 		 */
-		SetPageHasHWPoisoned(hpage);
+		folio_set_has_hwpoisoned(folio);
 		if (try_to_split_thp_page(p) < 0) {
 			res = action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);
 			goto unlock_mutex;
 		}
 		VM_BUG_ON_PAGE(!page_count(p), p);
+		folio = page_folio(p);
 	}
 
 	/*
@@ -2308,9 +2309,9 @@ int memory_failure(unsigned long pfn, int flags)
 	 * The check (unnecessarily) ignores LRU pages being isolated and
 	 * walked by the page reclaim code, however that's not a big loss.
 	 */
-	shake_page(p);
+	shake_folio(folio);
 
-	lock_page(p);
+	folio_lock(folio);
 
 	/*
 	 * We're only intended to deal with the non-Compound page here.
@@ -2318,11 +2319,11 @@ int memory_failure(unsigned long pfn, int flags)
 	 * race window. If this happens, we could try again to hopefully
 	 * handle the page next round.
 	 */
-	if (PageCompound(p)) {
+	if (folio_test_large(folio)) {
 		if (retry) {
 			ClearPageHWPoison(p);
-			unlock_page(p);
-			put_page(p);
+			folio_unlock(folio);
+			folio_put(folio);
 			flags &= ~MF_COUNT_INCREASED;
 			retry = false;
 			goto try_again;
@@ -2338,29 +2339,29 @@ int memory_failure(unsigned long pfn, int flags)
 	 * folio_remove_rmap_*() in try_to_unmap_one(). So to determine page
 	 * status correctly, we save a copy of the page flags at this time.
 	 */
-	page_flags = p->flags;
+	page_flags = folio->flags;
 
 	if (hwpoison_filter(p)) {
 		ClearPageHWPoison(p);
-		unlock_page(p);
-		put_page(p);
+		folio_unlock(folio);
+		folio_put(folio);
 		res = -EOPNOTSUPP;
 		goto unlock_mutex;
 	}
 
 	/*
-	 * __munlock_folio() may clear a writeback page's LRU flag without
-	 * page_lock. We need wait writeback completion for this page or it
-	 * may trigger vfs BUG while evict inode.
+	 * __munlock_folio() may clear a writeback folio's LRU flag without
+	 * the folio lock. We need to wait for writeback completion for this
+	 * folio or it may trigger a vfs BUG while evicting inode.
 	 */
-	if (!PageLRU(p) && !PageWriteback(p))
+	if (!folio_test_lru(folio) && !folio_test_writeback(folio))
 		goto identify_page_state;
 
 	/*
 	 * It's very difficult to mess with pages currently under IO
 	 * and in many cases impossible, so we just avoid it here.
 	 */
-	wait_on_page_writeback(p);
+	folio_wait_writeback(folio);
 
 	/*
 	 * Now take care of user space mappings.
@@ -2374,7 +2375,8 @@ int memory_failure(unsigned long pfn, int flags)
 	/*
 	 * Torn down by someone else?
 	 */
-	if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
+	if (folio_test_lru(folio) && !folio_test_swapcache(folio) &&
+	    folio->mapping == NULL) {
 		res = action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);
 		goto unlock_page;
 	}
@@ -2384,7 +2386,7 @@ int memory_failure(unsigned long pfn, int flags)
 	mutex_unlock(&mf_mutex);
 	return res;
 unlock_page:
-	unlock_page(p);
+	folio_unlock(folio);
 unlock_mutex:
 	mutex_unlock(&mf_mutex);
 	return res;
-- 
2.43.0