Date:   Mon, 18 Jan 2021 17:01:44 +0000
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     linux-fsdevel@...r.kernel.org, linux-mm@...ck.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 23/27] mm: Convert lock_page_or_retry to lock_folio_or_retry

There's already a hidden compound_head() call in trylock_page(), so
just make it explicit in the caller, which may later have a folio
for its own reasons.  This saves a call to compound_head() inside
__lock_page_or_retry().

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 include/linux/pagemap.h | 10 +++++-----
 mm/filemap.c            | 16 +++++++---------
 mm/memory.c             | 10 +++++-----
 3 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index d28b53f91275..d287e1a680e8 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -621,7 +621,7 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page,
 void __lock_folio(struct folio *folio);
 int __lock_folio_killable(struct folio *folio);
 int __lock_folio_async(struct folio *folio, struct wait_page_queue *wait);
-extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
+int __lock_folio_or_retry(struct folio *folio, struct mm_struct *mm,
 				unsigned int flags);
 void unlock_folio(struct folio *folio);
 
@@ -702,17 +702,17 @@ static inline int lock_folio_async(struct folio *folio,
 }
 
 /*
- * lock_page_or_retry - Lock the page, unless this would block and the
+ * lock_folio_or_retry - Lock the folio, unless this would block and the
  * caller indicated that it can handle a retry.
  *
  * Return value and mmap_lock implications depend on flags; see
- * __lock_page_or_retry().
+ * __lock_folio_or_retry().
  */
-static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
+static inline int lock_folio_or_retry(struct folio *folio, struct mm_struct *mm,
 				     unsigned int flags)
 {
 	might_sleep();
-	return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
+	return trylock_folio(folio) || __lock_folio_or_retry(folio, mm, flags);
 }
 
 /*
diff --git a/mm/filemap.c b/mm/filemap.c
index 7670e0c7dd97..4ece44f694f6 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1538,20 +1538,18 @@ int __lock_folio_async(struct folio *folio, struct wait_page_queue *wait)
 
 /*
  * Return values:
- * 1 - page is locked; mmap_lock is still held.
- * 0 - page is not locked.
+ * 1 - folio is locked; mmap_lock is still held.
+ * 0 - folio is not locked.
  *     mmap_lock has been released (mmap_read_unlock(), unless flags had both
  *     FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
  *     which case mmap_lock is still held.
  *
  * If neither ALLOW_RETRY nor KILLABLE are set, will always return 1
- * with the page locked and the mmap_lock unperturbed.
+ * with the folio locked and the mmap_lock unperturbed.
  */
-int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
+int __lock_folio_or_retry(struct folio *folio, struct mm_struct *mm,
 			 unsigned int flags)
 {
-	struct folio *folio = page_folio(page);
-
 	if (fault_flag_allow_retry_first(flags)) {
 		/*
 		 * CAUTION! In this case, mmap_lock is not released
@@ -1562,9 +1560,9 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
 
 		mmap_read_unlock(mm);
 		if (flags & FAULT_FLAG_KILLABLE)
-			wait_on_page_locked_killable(page);
+			wait_on_folio_locked_killable(folio);
 		else
-			wait_on_page_locked(page);
+			wait_on_folio_locked(folio);
 		return 0;
 	}
 	if (flags & FAULT_FLAG_KILLABLE) {
@@ -2749,7 +2747,7 @@ loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start,
  * @page - the page to lock.
  * @fpin - the pointer to the file we may pin (or is already pinned).
  *
- * This works similar to lock_page_or_retry in that it can drop the mmap_lock.
+ * This works similar to lock_folio_or_retry in that it can drop the mmap_lock.
  * It differs in that it actually returns the page locked if it returns 1 and 0
  * if it couldn't lock the page.  If we did have to drop the mmap_lock then fpin
  * will point to the pinned file and needs to be fput()'ed at a later point.
diff --git a/mm/memory.c b/mm/memory.c
index 8079c181efff..f5490cafe531 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3352,7 +3352,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 		goto out_release;
 	}
 
-	locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
+	locked = lock_folio_or_retry(page_folio(page), vma->vm_mm, vmf->flags);
 
 	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
 	if (!locked) {
@@ -4104,7 +4104,7 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
  * We enter with non-exclusive mmap_lock (to exclude vma changes,
  * but allow concurrent faults).
  * The mmap_lock may have been released depending on flags and our
- * return value.  See filemap_fault() and __lock_page_or_retry().
+ * return value.  See filemap_fault() and __lock_folio_or_retry().
  * If mmap_lock is released, vma may become invalid (for example
  * by other thread calling munmap()).
  */
@@ -4338,7 +4338,7 @@ static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
  * concurrent faults).
  *
  * The mmap_lock may have been released depending on flags and our return value.
- * See filemap_fault() and __lock_page_or_retry().
+ * See filemap_fault() and __lock_folio_or_retry().
  */
 static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
 {
@@ -4431,7 +4431,7 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
  * By the time we get here, we already hold the mm semaphore
  *
  * The mmap_lock may have been released depending on flags and our
- * return value.  See filemap_fault() and __lock_page_or_retry().
+ * return value.  See filemap_fault() and __lock_folio_or_retry().
  */
 static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
 		unsigned long address, unsigned int flags)
@@ -4587,7 +4587,7 @@ static inline void mm_account_fault(struct pt_regs *regs,
  * By the time we get here, we already hold the mm semaphore
  *
  * The mmap_lock may have been released depending on flags and our
- * return value.  See filemap_fault() and __lock_page_or_retry().
+ * return value.  See filemap_fault() and __lock_folio_or_retry().
  */
 vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
 			   unsigned int flags, struct pt_regs *regs)
-- 
2.29.2

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