linux-kernel - Re: [PATCH] ext2: Update also inode on disk when dir is IS

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Message-ID: <20090114151234.GG19950@duck.suse.cz>
Date:	Wed, 14 Jan 2009 16:12:34 +0100
From:	Jan Kara <jack@...e.cz>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org,
	linux-kernel@...r.kernel.org, pavel@...e.cz
Subject: Re: [PATCH] ext2: Update also inode on disk when dir is IS_DIRSYNC

On Tue 13-01-09 15:17:16, Andrew Morton wrote:
> On Tue, 13 Jan 2009 13:42:02 +0100
> Jan Kara <jack@...e.cz> wrote:
> 
> > We used to just write changed page for IS_DIRSYNC inodes. But we also have to
> > update directory inode itself just for the case that we've allocated a new
> > block and changed i_size.
> > 
> > Signed-off-by: Jan Kara <jack@...e.cz>
> > CC: Pavel Machek <pavel@...e.cz>
> > ---
> >  fs/ext2/dir.c |    5 ++---
> >  1 files changed, 2 insertions(+), 3 deletions(-)
> > 
> >   Andrew, would you please merge the patch? Ext3 and ext4 don't have this
> > problem BTW.
> > 
> > diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
> > index 9a0fc40..7fba549 100644
> > --- a/fs/ext2/dir.c
> > +++ b/fs/ext2/dir.c
> > @@ -94,11 +94,10 @@ static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
> >  		i_size_write(dir, pos+len);
> >  		mark_inode_dirty(dir);
> >  	}
> > +	unlock_page(page);
> >  
> >  	if (IS_DIRSYNC(dir))
> > -		err = write_one_page(page, 1);
> > -	else
> > -		unlock_page(page);
> > +		err = ext2_sync_inode(dir);
> >  
> 
> But with this change we no longer sync the data page?  Don't we need
> something like this:
  Oh, correct, we do. I was confused by sync_inode() calling fdatawrite()
but did not realize that the way ext2_sync_inode() calls it has start ==
end == 0. Thanks for spotting this.

> static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
> {
> 	struct address_space *mapping = page->mapping;
> 	struct inode *dir = mapping->host;
> 	int err = 0;
> 
> 	dir->i_version++;
> 	block_write_end(NULL, mapping, pos, len, len, page, NULL);
> 
> 	if (pos+len > dir->i_size) {
> 		i_size_write(dir, pos+len);
> 		mark_inode_dirty(dir);
> 	}
> 
> 	if (IS_DIRSYNC(dir)) {
> 		err = write_one_page(page, 1);
> 		if (err == 0)
> 			err = ext2_sync_inode(dir);
> 	} else {
> 		unlock_page(page);
> 	}
> 
> 	return err;
> }
> 
> ?
  Yes, I'll send you a new version of the patch and also send refreshed
second patch with blkdev_issue_flush() calls.

								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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