From: Christoph Hellwig <hch@lst.de>
To: Florian Weimer <fweimer@redhat.com>
Cc: Hans Holmberg <hans.holmberg@wdc.com>,
linux-xfs@vger.kernel.org, Carlos Maiolino <cem@kernel.org>,
Dave Chinner <david@fromorbit.com>,
"Darrick J . Wong" <djwong@kernel.org>,
Christoph Hellwig <hch@lst.de>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
libc-alpha@sourceware.org
Subject: Re: [RFC] xfs: fake fallocate success for always CoW inodes
Date: Thu, 6 Nov 2025 14:52:12 +0100 [thread overview]
Message-ID: <20251106135212.GA10477@lst.de> (raw)
In-Reply-To: <lhuikfngtlv.fsf@oldenburg.str.redhat.com>
On Thu, Nov 06, 2025 at 02:48:12PM +0100, Florian Weimer wrote:
> * Hans Holmberg:
>
> > We don't support preallocations for CoW inodes and we currently fail
> > with -EOPNOTSUPP, but this causes an issue for users of glibc's
> > posix_fallocate[1]. If fallocate fails, posix_fallocate falls back on
> > writing actual data into the range to try to allocate blocks that way.
> > That does not actually gurantee anything for CoW inodes however as we
> > write out of place.
>
> Why doesn't fallocate trigger the copy instead? Isn't this what the
> user is requesting?
What copy?
next prev parent reply other threads:[~2025-11-06 13:52 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-06 13:35 [RFC] xfs: fake fallocate success for always CoW inodes Hans Holmberg
2025-11-06 13:48 ` Florian Weimer
2025-11-06 13:52 ` Christoph Hellwig [this message]
2025-11-06 14:42 ` Matthew Wilcox
2025-11-06 14:46 ` Christoph Hellwig
2025-11-11 8:31 ` Hans Holmberg
2025-11-11 9:05 ` hch
2025-11-11 9:50 ` Florian Weimer
2025-11-11 13:40 ` hch
2025-11-06 16:31 ` Florian Weimer
2025-11-06 17:05 ` Christoph Hellwig
2025-11-08 12:30 ` Florian Weimer
2025-11-09 22:15 ` Dave Chinner
2025-11-10 5:27 ` Florian Weimer
2025-11-10 9:38 ` Christoph Hellwig
2025-11-10 10:03 ` Florian Weimer
2025-11-10 20:28 ` Dave Chinner
2025-11-11 8:56 ` Christoph Hellwig
2025-11-10 9:37 ` Christoph Hellwig
2025-11-10 9:44 ` Florian Weimer
2025-11-10 21:33 ` Dave Chinner
2025-11-11 9:04 ` Christoph Hellwig
2025-11-11 9:30 ` Florian Weimer
2025-11-10 9:31 ` Christoph Hellwig
2025-11-10 9:48 ` truncatat? was, " Christoph Hellwig
2025-11-10 10:00 ` Florian Weimer
2025-11-10 9:49 ` Florian Weimer
2025-11-10 9:52 ` Christoph Hellwig
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