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 14:17:53 +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 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'...

								Honza

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