2 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2862009f9573..3bf46655b50a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -144,6 +144,7 @@ extern pgprot_t protection_map[16];
 #define FAULT_FLAG_WRITE        0x01    /* Fault was a write access */
 #define FAULT_FLAG_NONLINEAR    0x02    /* Fault was via a nonlinear mapping */
 #define FAULT_FLAG_MKWRITE      0x04    /* Fault was mkwrite of existing pte */
+#define FAULT_FLAG_ALLOW_RETRY  0x08    /* Retry fault if blocking */
 
 /*
  * This interface is used by x86 PAT code to identify a pfn mapping that is
@@ -723,6 +724,7 @@ static inline int page_mapped(struct page *page)
 
 #define VM_FAULT_NOPAGE 0x0100  /* ->fault installed the pte, not return page */
 #define VM_FAULT_LOCKED 0x0200  /* ->fault locked the returned page */
+#define VM_FAULT_RETRY  0x0400  /* ->fault blocked, must retry */
 
 #define VM_FAULT_HWPOISON_LARGE_MASK 0xf000 /* encodes hpage index for large hwpoison */
 
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e12cdc6d79ee..2d1ffe3cf1ee 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -299,6 +299,8 @@ 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);
 extern void __lock_page_nosync(struct page *page);
+extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
+                                unsigned int flags);
 extern void unlock_page(struct page *page);
 
 static inline void __set_page_locked(struct page *page)
@@ -351,6 +353,17 @@ static inline void lock_page_nosync(struct page *page)
 }
         
 /*
+ * lock_page_or_retry - Lock the page, unless this would block and the
+ * caller indicated that it can handle a retry.
+ */
+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);
+}
+
+/*
  * This is exported only for wait_on_page_locked/wait_on_page_writeback.
  * Never use this directly!
  */