[PATCH v2 3/5] mm: Move folio_lock_or_retry() and drop __folio_lock_or_retry()

[Barry Song (Xiaomi)]

folio_lock_or_retry() is effectively only used in mm/memory.c,
not in the filemap code. Move it there and make it static.

The helper __folio_lock_or_retry() can be folded into
folio_lock_or_retry(), allowing it to be removed.

Signed-off-by: Barry Song (Xiaomi) <baohua at kernel.org>
---
 include/linux/pagemap.h | 17 -------------
 mm/filemap.c            | 45 ----------------------------------
 mm/memory.c             | 53 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 62 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 1f50991b43e3..500ab783bf70 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -1101,7 +1101,6 @@ 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);
-vm_fault_t __folio_lock_or_retry(struct folio *folio, struct vm_fault *vmf);
 void unlock_page(struct page *page);
 void folio_unlock(struct folio *folio);
 
@@ -1198,22 +1197,6 @@ static inline int folio_lock_killable(struct folio *folio)
 	return 0;
 }
 
-/*
- * folio_lock_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
- * __folio_lock_or_retry().
- */
-static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
-					     struct vm_fault *vmf)
-{
-	might_sleep();
-	if (!folio_trylock(folio))
-		return __folio_lock_or_retry(folio, vmf);
-	return 0;
-}
-
 /*
  * This is exported only for folio_wait_locked/folio_wait_writeback, etc.,
  * and should not be used directly.
diff --git a/mm/filemap.c b/mm/filemap.c
index a045b771e8de..b532d6cbafc8 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1740,51 +1740,6 @@ static int __folio_lock_async(struct folio *folio, struct wait_page_queue *wait)
 	return ret;
 }
 
-/*
- * Return values:
- * 0 - folio is locked.
- * non-zero - folio is not locked.
- *     mmap_lock or per-VMA lock has been released (mmap_read_unlock() or
- *     vma_end_read()), unless flags had both FAULT_FLAG_ALLOW_RETRY and
- *     FAULT_FLAG_RETRY_NOWAIT set, in which case the lock is still held.
- *
- * If neither ALLOW_RETRY nor KILLABLE are set, will always return 0
- * with the folio locked and the mmap_lock/per-VMA lock is left unperturbed.
- */
-vm_fault_t __folio_lock_or_retry(struct folio *folio, struct vm_fault *vmf)
-{
-	unsigned int flags = vmf->flags;
-
-	if (fault_flag_allow_retry_first(flags)) {
-		/*
-		 * CAUTION! In this case, mmap_lock/per-VMA lock is not
-		 * released even though returning VM_FAULT_RETRY.
-		 */
-		if (flags & FAULT_FLAG_RETRY_NOWAIT)
-			return VM_FAULT_RETRY;
-
-		release_fault_lock(vmf);
-		if (flags & FAULT_FLAG_KILLABLE)
-			folio_wait_locked_killable(folio);
-		else
-			folio_wait_locked(folio);
-		return VM_FAULT_RETRY;
-	}
-	if (flags & FAULT_FLAG_KILLABLE) {
-		bool ret;
-
-		ret = __folio_lock_killable(folio);
-		if (ret) {
-			release_fault_lock(vmf);
-			return VM_FAULT_RETRY;
-		}
-	} else {
-		__folio_lock(folio);
-	}
-
-	return 0;
-}
-
 /**
  * page_cache_next_miss() - Find the next gap in the page cache.
  * @mapping: Mapping.
diff --git a/mm/memory.c b/mm/memory.c
index 00ee1599d637..0c740ca363cc 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4442,6 +4442,59 @@ void unmap_mapping_range(struct address_space *mapping,
 }
 EXPORT_SYMBOL(unmap_mapping_range);
 
+/*
+ * folio_lock_or_retry - Lock the folio, unless this would block and the
+ * caller indicated that it can handle a retry.
+ *
+ * Return values:
+ * 0 - folio is locked.
+ * non-zero - folio is not locked.
+ *     mmap_lock or per-VMA lock has been released (mmap_read_unlock() or
+ *     vma_end_read()), unless flags had both FAULT_FLAG_ALLOW_RETRY and
+ *     FAULT_FLAG_RETRY_NOWAIT set, in which case the lock is still held.
+ *
+ * If neither ALLOW_RETRY nor KILLABLE are set, will always return 0
+ * with the folio locked and the mmap_lock/per-VMA lock is left unperturbed.
+ */
+static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
+					     struct vm_fault *vmf)
+{
+	unsigned int flags = vmf->flags;
+
+	might_sleep();
+	if (folio_trylock(folio))
+		return 0;
+
+	if (fault_flag_allow_retry_first(flags)) {
+		/*
+		 * CAUTION! In this case, mmap_lock/per-VMA lock is not
+		 * released even though returning VM_FAULT_RETRY.
+		 */
+		if (flags & FAULT_FLAG_RETRY_NOWAIT)
+			return VM_FAULT_RETRY;
+
+		release_fault_lock(vmf);
+		if (flags & FAULT_FLAG_KILLABLE)
+			folio_wait_locked_killable(folio);
+		else
+			folio_wait_locked(folio);
+		return VM_FAULT_RETRY;
+	}
+	if (flags & FAULT_FLAG_KILLABLE) {
+		bool ret;
+
+		ret = __folio_lock_killable(folio);
+		if (ret) {
+			release_fault_lock(vmf);
+			return VM_FAULT_RETRY;
+		}
+	} else {
+		__folio_lock(folio);
+	}
+
+	return 0;
+}
+
 /*
  * Restore a potential device exclusive pte to a working pte entry
  */
-- 
2.39.3 (Apple Git-146)