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From:   OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
To:     Jeff Layton <jlayton@kernel.org>
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Subject: Re: [PATCH v7 05/13] fat: make fat_update_time get its own timestamp
In-Reply-To: <52bead1d6a33fec89944b96e2ec20d1ea8747a9a.camel@kernel.org> (Jeff
        Layton's message of "Wed, 09 Aug 2023 06:10:53 -0400")
References: <20230807-mgctime-v7-0-d1dec143a704@kernel.org>
        <20230807-mgctime-v7-5-d1dec143a704@kernel.org>
        <87msz08vc7.fsf@mail.parknet.co.jp>
        <52bead1d6a33fec89944b96e2ec20d1ea8747a9a.camel@kernel.org>
Date:   Wed, 09 Aug 2023 22:36:29 +0900
Message-ID: <878rak8hia.fsf@mail.parknet.co.jp>
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Jeff Layton <jlayton@kernel.org> writes:

> On Wed, 2023-08-09 at 17:37 +0900, OGAWA Hirofumi wrote:
>> Jeff Layton <jlayton@kernel.org> writes:
>> 
>> > Also, it may be that things have changed by the time we get to calling
>> > fat_update_time after checking inode_needs_update_time. Ensure that we
>> > attempt the i_version bump if any of the S_* flags besides S_ATIME are
>> > set.
>> 
>> I'm not sure what it meaning though, this is from
>> generic_update_time(). Are you going to change generic_update_time()
>> too? If so, it doesn't break lazytime feature?
>> 
>
> Yes. generic_update_time is also being changed in a similar fashion.
> This shouldn't break the lazytime feature: lazytime is all about how and
> when timestamps get written to disk. This work is all about which
> clocksource the timestamps originally come from.

I can only find the following update in this series, another series
updates generic_update_time()? The patch updates only if S_VERSION is
set.

Your fat patch sets I_DIRTY_SYNC always instead of I_DIRTY_TIME. When I
last time checked lazytime, and it was depending on I_DIRTY_TIME.

Are you sure it doesn't break lazytime? I'm totally confusing, and
really similar with generic_update_time()?

Thanks.

+/**
+ * generic_update_time - update the timestamps on the inode
+ * @inode: inode to be updated
+ * @flags: S_* flags that needed to be updated
+ *
+ * The update_time function is called when an inode's timestamps need to be
+ * updated for a read or write operation. In the case where any of S_MTIME, S_CTIME,
+ * or S_VERSION need to be updated we attempt to update all three of them. S_ATIME
+ * updates can be handled done independently of the rest.
+ *
+ * Returns a S_* mask indicating which fields were updated.
+ */
+int generic_update_time(struct inode *inode, int flags)
+{
+	int updated = inode_update_timestamps(inode, flags);
+	int dirty_flags = 0;
 
+	if (updated & (S_ATIME|S_MTIME|S_CTIME))
+		dirty_flags = inode->i_sb->s_flags & SB_LAZYTIME ? I_DIRTY_TIME : I_DIRTY_SYNC;
+	if (updated & S_VERSION)
+		dirty_flags |= I_DIRTY_SYNC;
 	__mark_inode_dirty(inode, dirty_flags);
-	return 0;
+	return updated;
 }

>> > -	if ((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false))
>> > +	if ((flags & (S_VERSION|S_CTIME|S_MTIME)) && inode_maybe_inc_iversion(inode, false))
>> >  		dirty_flags |= I_DIRTY_SYNC;
>> >  
>> >  	__mark_inode_dirty(inode, dirty_flags);
>> 

-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>