Commit 13a79a47 authored Dec 13, 2011 by Yongqiang Yang Committed by Theodore Ts'o Dec 13, 2011

ext4: avoid potential hang in mpage_submit_io() when blocksize < pagesize



If there is an unwritten but clean buffer in a page and there is a
dirty buffer after the buffer, then mpage_submit_io does not write the
dirty buffer out.  As a result, da_writepages loops forever.

This patch fixes the problem by checking dirty flag.

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org

parent ea51d132

fs/ext4/inode.c

+5 −2

Original line number	Original line	Diff line number	Diff line
	@@ -1339,8 +1339,11 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
	clear_buffer_unwritten(bh);		clear_buffer_unwritten(bh);
	}		}

	/* skip page if block allocation undone */		/*
	if (buffer_delay(bh) \|\| buffer_unwritten(bh))		* skip page if block allocation undone and
			* block is dirty
			*/
			if (ext4_bh_delay_or_unwritten(NULL, bh))
	skip_page = 1;		skip_page = 1;
	bh = bh->b_this_page;		bh = bh->b_this_page;
	block_start += bh->b_size;		block_start += bh->b_size;