get rid of nobh_write_begin_newtrunc

Move the call to vmtruncate to get rid of accessive blocks to the only
remaining caller and rename the non-truncating version to nobh_write_begin.

Get rid of the superflous file argument to it while we're at it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/buffer.c

@@ -2510,11 +2510,11 @@ static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
 }
 
 /*
- * Filesystems implementing the new truncate sequence should use the
- * _newtrunc postfix variant which won't incorrectly call vmtruncate.
+ * On entry, the page is fully not uptodate.
+ * On exit the page is fully uptodate in the areas outside (from,to)
  * The filesystem needs to handle block truncation upon failure.
  */
-int nobh_write_begin_newtrunc(struct file *file, struct address_space *mapping,
+int nobh_write_begin(struct address_space *mapping,
 			loff_t pos, unsigned len, unsigned flags,
 			struct page **pagep, void **fsdata,
 			get_block_t *get_block)
@@ -2547,7 +2547,7 @@ int nobh_write_begin_newtrunc(struct file *file, struct address_space *mapping,
 		unlock_page(page);
 		page_cache_release(page);
 		*pagep = NULL;
-		return block_write_begin_newtrunc(file, mapping, pos, len,
+		return block_write_begin_newtrunc(NULL, mapping, pos, len,
 					flags, pagep, fsdata, get_block);
 	}
 
@@ -2654,35 +2654,6 @@ int nobh_write_begin_newtrunc(struct file *file, struct address_space *mapping,
 
 	return ret;
 }
-EXPORT_SYMBOL(nobh_write_begin_newtrunc);
-
-/*
- * On entry, the page is fully not uptodate.
- * On exit the page is fully uptodate in the areas outside (from,to)
- */
-int nobh_write_begin(struct file *file, struct address_space *mapping,
-			loff_t pos, unsigned len, unsigned flags,
-			struct page **pagep, void **fsdata,
-			get_block_t *get_block)
-{
-	int ret;
-
-	ret = nobh_write_begin_newtrunc(file, mapping, pos, len, flags,
-					pagep, fsdata, get_block);
-
-	/*
-	 * prepare_write() may have instantiated a few blocks
-	 * outside i_size.  Trim these off again. Don't need
-	 * i_size_read because we hold i_mutex.
-	 */
-	if (unlikely(ret)) {
-		loff_t isize = mapping->host->i_size;
-		if (pos + len > isize)
-			vmtruncate(mapping->host, isize);
-	}
-
-	return ret;
-}
 EXPORT_SYMBOL(nobh_write_begin);
 
 int nobh_write_end(struct file *file, struct address_space *mapping,

fs/ext2/inode.c

@@ -806,13 +806,8 @@ ext2_nobh_write_begin(struct file *file, struct address_space *mapping,
 {
 	int ret;
 
-	/*
-	 * Dir-in-pagecache still uses ext2_write_begin. Would have to rework
-	 * directory handling code to pass around offsets rather than struct
-	 * pages in order to make this work easily.
-	 */
-	ret = nobh_write_begin_newtrunc(file, mapping, pos, len, flags, pagep,
-						fsdata, ext2_get_block);
+	ret = nobh_write_begin(mapping, pos, len, flags, pagep, fsdata,
+			       ext2_get_block);
 	if (ret < 0)
 		ext2_write_failed(mapping, pos + len);
 	return ret;

fs/jfs/inode.c

@@ -303,8 +303,17 @@ static int jfs_write_begin(struct file *file, struct address_space *mapping,
 				loff_t pos, unsigned len, unsigned flags,
 				struct page **pagep, void **fsdata)
 {
-	return nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
+	int ret;
+
+	ret = nobh_write_begin(mapping, pos, len, flags, pagep, fsdata,
 				jfs_get_block);
+	if (unlikely(ret)) {
+		loff_t isize = mapping->host->i_size;
+		if (pos + len > isize)
+			vmtruncate(mapping->host, isize);
+	}
+
+	return ret;
 }
 
 static sector_t jfs_bmap(struct address_space *mapping, sector_t block)

include/linux/buffer_head.h

@@ -231,11 +231,7 @@ void block_sync_page(struct page *);
 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
 int file_fsync(struct file *, int);
-int nobh_write_begin_newtrunc(struct file *, struct address_space *,
-				loff_t, unsigned, unsigned,
-				struct page **, void **, get_block_t*);
-int nobh_write_begin(struct file *, struct address_space *,
-				loff_t, unsigned, unsigned,
+int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
 				struct page **, void **, get_block_t*);
 int nobh_write_end(struct file *, struct address_space *,
 				loff_t, unsigned, unsigned,