[RFC v2 06/10] mm: Add a range lock parameter to lock_page_or_retry()

[Laurent Dufour]

As lock_page_or_retry() may release the mmap_sem, it has to know about
the range applying to the lock when using range locks.

This patch adds a new range parameter to __lock_page_or_retry() and
deals with the callers.

Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx>
---
 include/linux/pagemap.h | 17 +++++++++++++++++
 mm/filemap.c            |  9 +++++++--
 mm/memory.c             |  3 ++-
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 316a19f6b635..efc62200d527 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -433,8 +433,13 @@ static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
 
 extern void __lock_page(struct page *page);
 extern int __lock_page_killable(struct page *page);
+#ifdef CONFIG_MEM_RANGE_LOCK
+extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
+				unsigned int flags, struct range_lock *range);
+#else
 extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
 				unsigned int flags);
+#endif
 extern void unlock_page(struct page *page);
 
 static inline int trylock_page(struct page *page)
@@ -473,12 +478,24 @@ static inline int lock_page_killable(struct page *page)
  * Return value and mmap_sem implications depend on flags; see
  * __lock_page_or_retry().
  */
+#ifdef CONFIG_MEM_RANGE_LOCK
 static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
+				     unsigned int flags,
+				     struct range_lock *range)
+{
+	might_sleep();
+	return trylock_page(page) || __lock_page_or_retry(page, mm, flags,
+							  range);
+}
+#else
+static inline int _lock_page_or_retry(struct page *page, struct mm_struct *mm,
 				     unsigned int flags)
 {
 	might_sleep();
 	return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
 }
+#define lock_page_or_retry(p, m, f, r) _lock_page_or_retry(p, m, f)
+#endif /* CONFIG_MEM_RANGE_LOCK */
 
 /*
  * This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
diff --git a/mm/filemap.c b/mm/filemap.c
index 6f1be573a5e6..adb7c15b8aa4 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1053,7 +1053,11 @@ EXPORT_SYMBOL_GPL(__lock_page_killable);
  * with the page locked and the mmap_sem unperturbed.
  */
 int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
-			 unsigned int flags)
+			 unsigned int flags
+#ifdef CONFIG_MEM_RANGE_LOCK
+			 , struct range_lock *range
+#endif
+	)
 {
 	if (flags & FAULT_FLAG_ALLOW_RETRY) {
 		/*
@@ -2234,7 +2238,8 @@ int filemap_fault(struct vm_fault *vmf)
 			goto no_cached_page;
 	}
 
-	if (!lock_page_or_retry(page, vmf->vma->vm_mm, vmf->flags)) {
+	if (!lock_page_or_retry(page, vmf->vma->vm_mm, vmf->flags,
+				vmf->lockrange)) {
 		put_page(page);
 		return ret | VM_FAULT_RETRY;
 	}
diff --git a/mm/memory.c b/mm/memory.c
index aa080e9814d4..99f62156616e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2737,7 +2737,8 @@ int do_swap_page(struct vm_fault *vmf)
 	}
 
 	swapcache = page;
-	locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
+	locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags,
+				    vmf->lockrange);
 
 	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
 	if (!locked) {
-- 
2.7.4