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From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Linux Filesystem Development List <linux-fsdevel@vger.kernel.org>,
	Ext4 Developers List <linux-ext4@vger.kernel.org>,
	linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [PATCH] writeback: avoid double-writing the inode on a lazytime expiration
Date: Wed, 11 Mar 2020 08:57:49 -0400	[thread overview]
Message-ID: <20200311125749.GA7159@mit.edu> (raw)
In-Reply-To: <20200311032009.GC46757@gmail.com>

On Tue, Mar 10, 2020 at 08:20:09PM -0700, Eric Biggers wrote:
> Thanks Ted!  This fixes the fscrypt test failure.
> 
> However, are you sure this works correctly on all filesystems?  I'm not sure
> about XFS.  XFS only implements ->dirty_inode(), not ->write_inode(), and in its
> ->dirty_inode() it does:
  ...
> 		if (flag != I_DIRTY_SYNC || !(inode->i_state & I_DIRTY_TIME))
> 			return;

That's true, but when the timestamps were originally modified,
dirty_inode() will be called with flag == I_DIRTY_TIME, which will
*not* be a no-op; which is to say, XFS will force the timestamps to be
updated on disk when the timestamps are first dirtied, because it
doesn't support I_DIRTY_TIME.

So I think we're fine.

					- Ted

WARNING: multiple messages have this Message-ID
From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Linux Filesystem Development List <linux-fsdevel@vger.kernel.org>,
	Ext4 Developers List <linux-ext4@vger.kernel.org>,
	linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] writeback: avoid double-writing the inode on a lazytime expiration
Date: Wed, 11 Mar 2020 08:57:49 -0400	[thread overview]
Message-ID: <20200311125749.GA7159@mit.edu> (raw)
In-Reply-To: <20200311032009.GC46757@gmail.com>

On Tue, Mar 10, 2020 at 08:20:09PM -0700, Eric Biggers wrote:
> Thanks Ted!  This fixes the fscrypt test failure.
> 
> However, are you sure this works correctly on all filesystems?  I'm not sure
> about XFS.  XFS only implements ->dirty_inode(), not ->write_inode(), and in its
> ->dirty_inode() it does:
  ...
> 		if (flag != I_DIRTY_SYNC || !(inode->i_state & I_DIRTY_TIME))
> 			return;

That's true, but when the timestamps were originally modified,
dirty_inode() will be called with flag == I_DIRTY_TIME, which will
*not* be a no-op; which is to say, XFS will force the timestamps to be
updated on disk when the timestamps are first dirtied, because it
doesn't support I_DIRTY_TIME.

So I think we're fine.

					- Ted


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  reply	other threads:[~2020-03-11 12:58 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-06  0:45 lazytime causing inodes to remain dirty after sync? Eric Biggers
2020-03-06  0:45 ` [f2fs-dev] " Eric Biggers
2020-03-07  2:00 ` [PATCH] writeback: avoid double-writing the inode on a lazytime expiration Theodore Ts'o
2020-03-07  2:00   ` [f2fs-dev] " Theodore Ts'o
2020-03-11  3:20   ` Eric Biggers
2020-03-11  3:20     ` [f2fs-dev] " Eric Biggers
2020-03-11 12:57     ` Theodore Y. Ts'o [this message]
2020-03-11 12:57       ` Theodore Y. Ts'o
2020-03-12  0:07       ` Dave Chinner
2020-03-12  0:07         ` [f2fs-dev] " Dave Chinner
2020-03-12 14:34         ` Christoph Hellwig
2020-03-12 14:34           ` [f2fs-dev] " Christoph Hellwig
2020-03-12 22:39           ` Dave Chinner
2020-03-12 22:39             ` [f2fs-dev] " Dave Chinner
2020-03-20  2:46           ` Theodore Y. Ts'o
2020-03-20  2:46             ` [f2fs-dev] " Theodore Y. Ts'o
2020-03-20  2:52             ` [PATCH 1/2] " Theodore Ts'o
2020-03-20  2:52               ` [f2fs-dev] " Theodore Ts'o
2020-03-20  2:52               ` [PATCH 2/2] writeback, xfs: call dirty_inode() with I_DIRTY_TIME_EXPIRED when appropriate Theodore Ts'o
2020-03-20  2:52                 ` [f2fs-dev] " Theodore Ts'o
2020-03-23 17:58                 ` Theodore Y. Ts'o
2020-03-23 17:58                   ` [f2fs-dev] " Theodore Y. Ts'o
2020-03-24  8:37                   ` Christoph Hellwig
2020-03-24  8:37                     ` [f2fs-dev] " Christoph Hellwig
2020-03-24 18:43                     ` Theodore Y. Ts'o
2020-03-24 18:43                       ` [f2fs-dev] " Theodore Y. Ts'o
2020-03-25  9:20               ` [PATCH 1/2] writeback: avoid double-writing the inode on a lazytime expiration Christoph Hellwig
2020-03-25  9:20                 ` [f2fs-dev] " Christoph Hellwig
2020-03-25 15:21                 ` Theodore Y. Ts'o
2020-03-25 15:21                   ` [f2fs-dev] " Theodore Y. Ts'o
2020-03-25 15:47                   ` Darrick J. Wong
2020-03-25 15:47                     ` [f2fs-dev] " Darrick J. Wong
2020-03-11 23:54     ` [PATCH] " Dave Chinner
2020-03-11 23:54       ` [f2fs-dev] " Dave Chinner

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