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

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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
This commit is contained in:
Yongqiang Yang 2011-12-13 21:51:55 -05:00 committed by Theodore Ts'o
parent ea51d132db
commit 13a79a4741
1 changed files with 5 additions and 2 deletions
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7
fs/ext4/inode.c
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@ -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;