Add lock_page_killable

This routine is like lock_page, but can be interrupted by a fatal signal

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index db8a410ae9e15a6daf9b64678fd3edefccdcc717..4b62a105622b1e8e38b294a32f426a42be0a8861 100644 (file)
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -157,6 +157,7 @@ static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
 }
 
 extern void FASTCALL(__lock_page(struct page *page));
+extern int FASTCALL(__lock_page_killable(struct page *page));
 extern void FASTCALL(__lock_page_nosync(struct page *page));
 extern void FASTCALL(unlock_page(struct page *page));
 
@@ -170,6 +171,19 @@ static inline void lock_page(struct page *page)
                __lock_page(page);
 }
 
+/*
+ * lock_page_killable is like lock_page but can be interrupted by fatal
+ * signals.  It returns 0 if it locked the page and -EINTR if it was
+ * killed while waiting.
+ */
+static inline int lock_page_killable(struct page *page)
+{
+       might_sleep();
+       if (TestSetPageLocked(page))
+               return __lock_page_killable(page);
+       return 0;
+}
+
 /*
  * lock_page_nosync should only be used if we can't pin the page's inode.
  * Doesn't play quite so well with block device plugging.

diff --git a/mm/filemap.c b/mm/filemap.c
index 188cf5fd3e8d4acedec4e74c05375238526506e5..ac8f690d288590c9f1c8603bd37272127c9cecf2 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -173,6 +173,12 @@ static int sync_page(void *word)
        return 0;
 }
 
+static int sync_page_killable(void *word)
+{
+       sync_page(word);
+       return fatal_signal_pending(current) ? -EINTR : 0;
+}
+
 /**
  * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
  * @mapping:   address space structure to write
@@ -577,6 +583,14 @@ void fastcall __lock_page(struct page *page)
 }
 EXPORT_SYMBOL(__lock_page);
 
+int fastcall __lock_page_killable(struct page *page)
+{
+       DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
+
+       return __wait_on_bit_lock(page_waitqueue(page), &wait,
+                                       sync_page_killable, TASK_KILLABLE);
+}
+
 /*
  * Variant of lock_page that does not require the caller to hold a reference
  * on the page's mapping.