linux-ext4 - Re: [PATCH 05/13] fs: don't call ->dirty_inode for lazytime timestamp updates

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Date:   Thu, 7 Jan 2021 14:18:53 +0100
From:   Jan Kara <jack@...e.cz>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net, linux-xfs@...r.kernel.org,
        Theodore Ts'o <tytso@....edu>, Christoph Hellwig <hch@....de>
Subject: Re: [PATCH 05/13] fs: don't call ->dirty_inode for lazytime
 timestamp updates

On Thu 07-01-21 14:17:53, Jan Kara wrote:
> On Mon 04-01-21 16:54:44, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@...gle.com>
> > 
> > There is no need to call ->dirty_inode for lazytime timestamp updates
> > (i.e. for __mark_inode_dirty(I_DIRTY_TIME)), since by the definition of
> > lazytime, filesystems must ignore these updates.  Filesystems only need
> > to care about the updated timestamps when they expire.
> > 
> > Therefore, only call ->dirty_inode when I_DIRTY_INODE is set.
> > 
> > Based on a patch from Christoph Hellwig:
> > https://lore.kernel.org/r/20200325122825.1086872-4-hch@lst.de
> > 
> > Signed-off-by: Eric Biggers <ebiggers@...gle.com>
> 
> ...
> 
> > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> > index 081e335cdee47..e3347fd6eb13a 100644
> > --- a/fs/fs-writeback.c
> > +++ b/fs/fs-writeback.c
> > @@ -2264,16 +2264,16 @@ void __mark_inode_dirty(struct inode *inode, int flags)
> >  	 * Don't do this for I_DIRTY_PAGES - that doesn't actually
> >  	 * dirty the inode itself
> >  	 */
> > -	if (flags & (I_DIRTY_INODE | I_DIRTY_TIME)) {
> > +	if (flags & I_DIRTY_INODE) {
> >  		trace_writeback_dirty_inode_start(inode, flags);
> >  
> >  		if (sb->s_op->dirty_inode)
> >  			sb->s_op->dirty_inode(inode, flags);
> 
> OK, but shouldn't we pass just (flags & I_DIRTY_INODE) to ->dirty_inode().
> Just to make it clear what the filesystem is supposed to consume in
> 'flags'...

Aha, you just did that in the following patch ;) So taking back my comment.

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