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From: Dave Chinner <david@fromorbit.com>
To: Theodore Ts'o <tytso@mit.edu>, Namjae Jeon <linkinjeon@gmail.com>,
	adilger.kernel@dilger.ca, bpm@sgi.com, elder@kernel.org,
	hch@infradead.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org,
	xfs@oss.sgi.com, a.sangwan@samsung.com,
	Namjae Jeon <namjae.jeon@samsung.com>
Subject: Re: [PATCH 1/3] fs: Introduce new flag FALLOC_FL_COLLAPSE_RANGE
Date: Thu, 1 Aug 2013 10:23:41 +1000	[thread overview]
Message-ID: <20130801002341.GI7118@dastard> (raw)
In-Reply-To: <20130731220154.GA11378@thunk.org>

On Wed, Jul 31, 2013 at 06:01:54PM -0400, Theodore Ts'o wrote:
> Have you considered what happens if you have a 10 megabyte file, of
> which the first 5 megs are mmap'ed into a userspace process.
> 
> Now suppose you call COLLAPASE_RANGE on a one megabyte range starting
> at offset 1024k from the beginning of the file.
> 
> Does the right thing happen to the mmap'ed region in memory?

Implementation detail. like a hole punch, it needs to invalidate the
range that it is operating over so mmap()d regions are refaulted
after the operation is done.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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WARNING: multiple messages have this Message-ID (diff)
From: Dave Chinner <david@fromorbit.com>
To: "Theodore Ts'o" <tytso@mit.edu>,
	Namjae Jeon <linkinjeon@gmail.com>,
	adilger.kernel@dilger.ca, bpm@sgi.com, elder@kernel.org,
	hch@infradead.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org,
	xfs@oss.sgi.com, a.sangwan@samsung.com,
	Namjae Jeon <namjae.jeon@samsung.com>
Subject: Re: [PATCH 1/3] fs: Introduce new flag FALLOC_FL_COLLAPSE_RANGE
Date: Thu, 1 Aug 2013 10:23:41 +1000	[thread overview]
Message-ID: <20130801002341.GI7118@dastard> (raw)
In-Reply-To: <20130731220154.GA11378@thunk.org>

On Wed, Jul 31, 2013 at 06:01:54PM -0400, Theodore Ts'o wrote:
> Have you considered what happens if you have a 10 megabyte file, of
> which the first 5 megs are mmap'ed into a userspace process.
> 
> Now suppose you call COLLAPASE_RANGE on a one megabyte range starting
> at offset 1024k from the beginning of the file.
> 
> Does the right thing happen to the mmap'ed region in memory?

Implementation detail. like a hole punch, it needs to invalidate the
range that it is operating over so mmap()d regions are refaulted
after the operation is done.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

  reply	other threads:[~2013-08-01  0:23 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-31 14:42 [PATCH 1/3] fs: Introduce new flag FALLOC_FL_COLLAPSE_RANGE Namjae Jeon
2013-07-31 14:42 ` Namjae Jeon
2013-07-31 22:01 ` Theodore Ts'o
2013-07-31 22:01   ` Theodore Ts'o
2013-08-01  0:23   ` Dave Chinner [this message]
2013-08-01  0:23     ` Dave Chinner
2013-08-01  0:46     ` Theodore Ts'o
2013-08-01  0:46       ` Theodore Ts'o
2013-08-01  0:54       ` Dave Chinner
2013-08-01  0:54         ` Dave Chinner
2013-08-01  1:07         ` Theodore Ts'o
2013-08-01  1:07           ` Theodore Ts'o
2013-08-01  2:59           ` Dave Chinner
2013-08-01  2:59             ` Dave Chinner
2013-08-01  4:06             ` Theodore Ts'o
2013-08-01  4:06               ` Theodore Ts'o
2013-08-01  4:32               ` Dave Chinner
2013-08-01  4:32                 ` Dave Chinner
2013-08-01  0:22 ` Dave Chinner
2013-08-01  0:22   ` Dave Chinner
2013-08-01  5:07   ` Namjae Jeon
2013-08-01  5:07     ` Namjae Jeon
2013-08-02  2:37     ` Dave Chinner
2013-08-02  2:37       ` Dave Chinner

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