[PATCH v14 022/138] mm/filemap: Add __folio_lock_or_retry()

Matthew Wilcox (Oracle)
2021-07-15T03:57:00Z

Convert __lock_page_or_retry() to __folio_lock_or_retry(). This actually
saves 4 bytes in the only caller of lock_page_or_retry() (due to better
register allocation) and saves the 14 byte cost of calling page_folio()
in __folio_lock_or_retry() for a total saving of 18 bytes. Also use
a bool for the return type.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
---
include/linux/pagemap.h | 11 +++++++----
mm/filemap.c | 20 +++++++++-----------
mm/memory.c | 8 ++++----
3 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 03fea8bbfd8e..626dbccbfb90 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -655,7 +655,7 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page,

void __folio_lock(struct folio *folio);
int __folio_lock_killable(struct folio *folio);
-extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
+bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
unsigned int flags);
void unlock_page(struct page *page);
void folio_unlock(struct folio *folio);
@@ -716,13 +716,16 @@ 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().
+ * __folio_lock_or_retry().
*/
-static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
+static inline bool 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 folio_trylock(folio) || __folio_lock_or_retry(folio, mm, flags);
}

/*
diff --git a/mm/filemap.c b/mm/filemap.c
index 04fb4a84cf0d..fb6398a532e5 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1625,48 +1625,46 @@ static int __folio_lock_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.
+ * true - folio is locked; mmap_lock is still held.
+ * false - 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,
+bool __folio_lock_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
* even though return 0.
*/
if (flags & FAULT_FLAG_RETRY_NOWAIT)
- return 0;
+ return false;

mmap_read_unlock(mm);
if (flags & FAULT_FLAG_KILLABLE)
folio_wait_locked_killable(folio);
else
folio_wait_locked(folio);
- return 0;
+ return false;
}
if (flags & FAULT_FLAG_KILLABLE) {
- int ret;
+ bool ret;

ret = __folio_lock_killable(folio);
if (ret) {
mmap_read_unlock(mm);
- return 0;
+ return false;
}
} else {
__folio_lock(folio);
}

- return 1;
+ return true;
}

/**
diff --git a/mm/memory.c b/mm/memory.c
index 747a01d495f2..2f111f9b3dbc 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4248,7 +4248,7 @@ 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 __folio_lock_or_retry().
* If mmap_lock is released, vma may become invalid (for example
* by other thread calling munmap()).
*/
@@ -4489,7 +4489,7 @@ 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 __folio_lock_or_retry().
*/
static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
{
@@ -4593,7 +4593,7 @@ 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 __folio_lock_or_retry().
*/
static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
unsigned long address, unsigned int flags)
@@ -4749,7 +4749,7 @@ 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 __folio_lock_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