reiserfs: truncate blocks not used by a write

It can happen that write does not use all the blocks allocated in
write_begin either because of some filesystem error (like ENOSPC) or
because page with data to write has been removed from memory.  We truncate
these blocks so that we don't have dangling blocks beyond i_size.

Cc: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/reiserfs/inode.c

@@ -2538,6 +2538,12 @@ static int reiserfs_writepage(struct page *page, struct writeback_control *wbc)
 	return reiserfs_write_full_page(page, wbc);
 }
 
+static void reiserfs_truncate_failed_write(struct inode *inode)
+{
+	truncate_inode_pages(inode->i_mapping, inode->i_size);
+	reiserfs_truncate_file(inode, 0);
+}
+
 static int reiserfs_write_begin(struct file *file,
 				struct address_space *mapping,
 				loff_t pos, unsigned len, unsigned flags,
@@ -2604,6 +2610,8 @@ static int reiserfs_write_begin(struct file *file,
 	if (ret) {
 		unlock_page(page);
 		page_cache_release(page);
+		/* Truncate allocated blocks */
+		reiserfs_truncate_failed_write(inode);
 	}
 	return ret;
 }
@@ -2701,9 +2709,7 @@ static int reiserfs_write_end(struct file *file, struct address_space *mapping,
 	 ** transaction tracking stuff when the size changes.  So, we have
 	 ** to do the i_size updates here.
 	 */
-	pos += copied;
-
-	if (pos > inode->i_size) {
+	if (pos + copied > inode->i_size) {
 		struct reiserfs_transaction_handle myth;
 		lock_depth = reiserfs_write_lock_once(inode->i_sb);
 		locked = true;
@@ -2721,7 +2727,7 @@ static int reiserfs_write_end(struct file *file, struct address_space *mapping,
 			goto journal_error;
 
 		reiserfs_update_inode_transaction(inode);
-		inode->i_size = pos;
+		inode->i_size = pos + copied;
 		/*
 		 * this will just nest into our transaction.  It's important
 		 * to use mark_inode_dirty so the inode gets pushed around on the
@@ -2751,6 +2757,10 @@ static int reiserfs_write_end(struct file *file, struct address_space *mapping,
 		reiserfs_write_unlock_once(inode->i_sb, lock_depth);
 	unlock_page(page);
 	page_cache_release(page);
+
+	if (pos + len > inode->i_size)
+		reiserfs_truncate_failed_write(inode);
+
 	return ret == 0 ? copied : ret;
 
       journal_error: