linux-kernel - Re: The bug of iput() removal from flusher thread?

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Date:	Mon, 19 Nov 2012 17:56:22 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	Jan Kara <jack@...e.cz>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: The bug of iput() removal from flusher thread?

OGAWA Hirofumi <hirofumi@...l.parknet.co.jp> writes:

> Hi,
>
> In 169ebd90131b2ffca74bb2dbe7eeacd39fb83714 commit, writeback doesn't
> __iget()/iput() anymore.
>
> This means nobody moves the inode to lru list. I.e.
>
> 	new_inode()
> 	dirty_inode()
> 	iput_final()
> 		/* keep inode without adding lru */
> 	flush indoes
>         /* clean inode is not on lru */
>
> I noticed this situation in my FS though, I think the same bug is on all
> FSes of linus tree too, after this commit.
>
> Am I missing the something?

This seems to be reproducible by the following,

#!/bin/sh

for i in $(seq -w 1000); do
	for j in $(seq -w 1000); do
        	for k in $(seq -w 1000); do
                	mkdir -p $i/$j
                        echo $i/$j/$k > $i/$j/$k
                        echo 2 > /proc/sys/vm/drop_caches
                done
        done
done

Some inodes never be reclaimed, and ls -l frees those inodes (stat(2)
does iget/iput).
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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