From: Christoph Hellwig <hch@infradead.org>
To: Andreas Dilger <adilger@dilger.ca>
Cc: Christoph Hellwig <hch@infradead.org>,
Avi Kivity <avi@scylladb.com>, Andres Freund <andres@anarazel.de>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-ext4@vger.kernel.org, linux-block@vger.kernel.org
Subject: Re: fallocate(FALLOC_FL_ZERO_RANGE_BUT_REALLY) to avoid unwritten extents?
Date: Tue, 12 Jan 2021 18:43:39 +0000 [thread overview]
Message-ID: <20210112184339.GA1238746@infradead.org> (raw)
In-Reply-To: <C8811877-48A9-4199-9F28-20F5B071AE36@dilger.ca>
On Tue, Jan 12, 2021 at 11:39:58AM -0700, Andreas Dilger wrote:
> > XFS already has a XFS_IOC_ALLOCSP64 that is defined to actually
> > allocate written extents. It does not currently use
> > blkdev_issue_zeroout, but could be changed pretty trivially to do so.
> >
> >> But note it will need to be plumbed down to md and dm to be generally
> >> useful.
> >
> > DM and MD already support mddev_check_write_zeroes, at least for the
> > usual targets.
>
> Similarly, ext4 also has EXT4_GET_BLOCKS_CREATE_ZERO that can allocate zero
> filled extents rather than unwritten extents (without clobbering existing
> data like FALLOC_FL_ZERO_RANGE does), and just needs a flag from fallocate()
> to trigger it. This is plumbed down to blkdev_issue_zeroout() as well.
XFS_IOC_ALLOCSP64 actually is an ioctl that has been around since 1995
on IRIX (as an fcntl).
next prev parent reply other threads:[~2021-01-12 18:44 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-30 6:28 fallocate(FALLOC_FL_ZERO_RANGE_BUT_REALLY) to avoid unwritten extents? Andres Freund
2021-01-04 18:19 ` Darrick J. Wong
2021-01-04 19:10 ` Andres Freund
2021-01-04 19:57 ` Avi Kivity
2021-01-12 18:16 ` Christoph Hellwig
2021-01-12 18:39 ` Andreas Dilger
2021-01-12 18:43 ` Christoph Hellwig [this message]
2021-01-12 18:51 ` Andreas Dilger
2021-01-12 21:14 ` Darrick J. Wong
2021-01-12 21:36 ` Andres Freund
2021-01-13 7:44 ` Avi Kivity
2021-01-19 3:44 ` Andreas Dilger
2021-01-04 19:17 ` Theodore Ts'o
2021-01-04 19:24 ` Matthew Wilcox
2021-01-04 20:29 ` Andres Freund
2021-01-04 22:40 ` Eric Sandeen
2021-01-06 22:52 ` Dave Chinner
2021-01-06 23:40 ` Andres Freund
2021-01-08 20:32 ` Dave Chinner
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