linux-ext4 - Re: [PATCH v2 11/12] ext4: simplify i_state checks in __ext4_update_other_inode

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Date:   Tue, 12 Jan 2021 14:25:21 +0100
From:   Christoph Hellwig <hch@....de>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     Christoph Hellwig <hch@....de>, linux-fsdevel@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        Theodore Ts'o <tytso@....edu>
Subject: Re: [PATCH v2 11/12] ext4: simplify i_state checks in
 __ext4_update_other_inode_time()

On Mon, Jan 11, 2021 at 12:23:40PM -0800, Eric Biggers wrote:
> > I think a descriptively named inline helper in fs.h would really improve
> > this..
> 
> Do you want this even though it is specific to how ext4 opportunisticly updates
> other inodes in the same inode block as the inode being updated?  That's the
> only reason that I_FREEING|I_WILL_FREE|I_NEW need to be checked; everywhere else
> justs want I_DIRTY_TIME.
> 
> We could add:
> 
> 	static inline bool other_inode_has_dirtytime(struct inode *inode)
> 	{
> 		return (inode->state & (I_FREEING | I_WILL_FREE |
> 					I_NEW | I_DIRTY_TIME)) == I_DIRTY_TIME;
> 	}
> 
> But it seems a bit weird when it's specific to ext4 at the moment.
> 
> Are you thinking that other filesystems will implement the same sort of
> opportunistic update, so we should add the helper now?

For my taste these checks for flags is way too much black magic and will
trivially break when people add new flags.  So having a helper next to
the definition of the I_* flags that is well documented would be very,
very helpful.  My preferred naming would be something along the lines
of 'inode_is_dirty_lazytime_only()'.