X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=mm%2Ftruncate.c;h=ac18edc30649247c49bdd330d17986041998976d;hb=da357d7aab5e47f5a9bd806980f4cbb1e76f523d;hp=e2e8a8a7eb9d8facfd7581998641e72f81b4c02d;hpb=ee3e542fec6e69bc9fb668698889a37d93950ddf;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

diff --git a/mm/truncate.c b/mm/truncate.c
index e2e8a8a..ac18edc 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -20,6 +20,7 @@
 #include <linux/buffer_head.h>	/* grr. try_to_release_page,
 				   do_invalidatepage */
 #include <linux/cleancache.h>
+#include <linux/rmap.h>
 #include "internal.h"
 
 
@@ -567,7 +568,6 @@ EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
 /**
  * truncate_pagecache - unmap and remove pagecache that has been truncated
  * @inode: inode
- * @oldsize: old file size
  * @newsize: new file size
  *
  * inode's new i_size must already be written before truncate_pagecache
@@ -580,7 +580,7 @@ EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
  * situations such as writepage being called for a page that has already
  * had its underlying blocks deallocated.
  */
-void truncate_pagecache(struct inode *inode, loff_t oldsize, loff_t newsize)
+void truncate_pagecache(struct inode *inode, loff_t newsize)
 {
 	struct address_space *mapping = inode->i_mapping;
 	loff_t holebegin = round_up(newsize, PAGE_SIZE);
@@ -614,16 +614,67 @@ EXPORT_SYMBOL(truncate_pagecache);
  */
 void truncate_setsize(struct inode *inode, loff_t newsize)
 {
-	loff_t oldsize;
+	loff_t oldsize = inode->i_size;
 
-	oldsize = inode->i_size;
 	i_size_write(inode, newsize);
-
-	truncate_pagecache(inode, oldsize, newsize);
+	if (newsize > oldsize)
+		pagecache_isize_extended(inode, oldsize, newsize);
+	truncate_pagecache(inode, newsize);
 }
 EXPORT_SYMBOL(truncate_setsize);
 
 /**
+ * pagecache_isize_extended - update pagecache after extension of i_size
+ * @inode:	inode for which i_size was extended
+ * @from:	original inode size
+ * @to:		new inode size
+ *
+ * Handle extension of inode size either caused by extending truncate or by
+ * write starting after current i_size. We mark the page straddling current
+ * i_size RO so that page_mkwrite() is called on the nearest write access to
+ * the page.  This way filesystem can be sure that page_mkwrite() is called on
+ * the page before user writes to the page via mmap after the i_size has been
+ * changed.
+ *
+ * The function must be called after i_size is updated so that page fault
+ * coming after we unlock the page will already see the new i_size.
+ * The function must be called while we still hold i_mutex - this not only
+ * makes sure i_size is stable but also that userspace cannot observe new
+ * i_size value before we are prepared to store mmap writes at new inode size.
+ */
+void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
+{
+	int bsize = 1 << inode->i_blkbits;
+	loff_t rounded_from;
+	struct page *page;
+	pgoff_t index;
+
+	WARN_ON(to > inode->i_size);
+
+	if (from >= to || bsize == PAGE_CACHE_SIZE)
+		return;
+	/* Page straddling @from will not have any hole block created? */
+	rounded_from = round_up(from, bsize);
+	if (to <= rounded_from || !(rounded_from & (PAGE_CACHE_SIZE - 1)))
+		return;
+
+	index = from >> PAGE_CACHE_SHIFT;
+	page = find_lock_page(inode->i_mapping, index);
+	/* Page not cached? Nothing to do */
+	if (!page)
+		return;
+	/*
+	 * See clear_page_dirty_for_io() for details why set_page_dirty()
+	 * is needed.
+	 */
+	if (page_mkclean(page))
+		set_page_dirty(page);
+	unlock_page(page);
+	page_cache_release(page);
+}
+EXPORT_SYMBOL(pagecache_isize_extended);
+
+/**
  * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
  * @inode: inode
  * @lstart: offset of beginning of hole