[PATCH v6 20/27] mm/filemap: Add __lock_folio_or_retry

Matthew Wilcox (Oracle)
2021-03-31T18:54:40Z

Convert __lock_page_or_retry() to __lock_folio_or_retry(). This actually
saves 4 bytes in the only caller of lock_page_or_retry() (due to better
register allocation) and saves the 20 byte cost of calling page_folio()
in __lock_folio_or_retry() for a total saving of 24 bytes.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
include/linux/pagemap.h | 9 ++++++---
mm/filemap.c | 10 ++++------
mm/memory.c | 8 ++++----
3 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 054e9dd7628e..43664bef7392 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -716,7 +716,7 @@ 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);
-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_page(struct page *page);
void unlock_folio(struct folio *folio);
@@ -778,13 +778,16 @@ static inline int lock_page_killable(struct page *page)
* 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,
unsigned int flags)
{
+ struct folio *folio;
might_sleep();
- return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
+
+ folio = page_folio(page);
+ return trylock_folio(folio) || __lock_folio_or_retry(folio, mm, flags);
}

/*
diff --git a/mm/filemap.c b/mm/filemap.c
index 84642e41c6b5..c0a986ac830f 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1582,20 +1582,18 @@ static 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
diff --git a/mm/memory.c b/mm/memory.c
index e66b11ac1659..d538441ccb49 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4077,7 +4077,7 @@ 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()).
*/
@@ -4309,7 +4309,7 @@ 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)
{
@@ -4413,7 +4413,7 @@ 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)
@@ -4569,7 +4569,7 @@ 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)
--
2.30.2