1 files changed, 9 insertions, 17 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index 8d595ab..5930e38 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1833,9 +1833,11 @@ void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
 }
 EXPORT_SYMBOL(page_zero_new_buffers);
 
-int block_prepare_write(struct page *page, unsigned from, unsigned to,
+int __block_write_begin(struct page *page, loff_t pos, unsigned len,
 		get_block_t *get_block)
 {
+	unsigned from = pos & (PAGE_CACHE_SIZE - 1);
+	unsigned to = from + len;
 	struct inode *inode = page->mapping->host;
 	unsigned block_start, block_end;
 	sector_t block;
@@ -1915,7 +1917,7 @@ int block_prepare_write(struct page *page, unsigned from, unsigned to,
 	}
 	return err;
 }
-EXPORT_SYMBOL(block_prepare_write);
+EXPORT_SYMBOL(__block_write_begin);
 
 static int __block_commit_write(struct inode *inode, struct page *page,
 		unsigned from, unsigned to)
@@ -1952,15 +1954,6 @@ static int __block_commit_write(struct inode *inode, struct page *page,
 	return 0;
 }
 
-int __block_write_begin(struct page *page, loff_t pos, unsigned len,
-		get_block_t *get_block)
-{
-	unsigned start = pos & (PAGE_CACHE_SIZE - 1);
-
-	return block_prepare_write(page, start, start + len, get_block);
-}
-EXPORT_SYMBOL(__block_write_begin);
-
 /*
  * block_write_begin takes care of the basic task of block allocation and
  * bringing partial write blocks uptodate first.
@@ -2378,7 +2371,7 @@ block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
 	else
 		end = PAGE_CACHE_SIZE;
 
-	ret = block_prepare_write(page, 0, end, get_block);
+	ret = __block_write_begin(page, 0, end, get_block);
 	if (!ret)
 		ret = block_commit_write(page, 0, end);
 
@@ -2465,11 +2458,10 @@ int nobh_write_begin(struct address_space *mapping,
 	*fsdata = NULL;
 
 	if (page_has_buffers(page)) {
-		unlock_page(page);
-		page_cache_release(page);
-		*pagep = NULL;
-		return block_write_begin(mapping, pos, len, flags, pagep,
-					 get_block);
+		ret = __block_write_begin(page, pos, len, get_block);
+		if (unlikely(ret))
+			goto out_release;
+		return ret;
 	}
 
 	if (PageMappedToDisk(page))