From: Jan Kara <jack@suse.cz>
To: Dave Chinner <david@fromorbit.com>
Cc: Josef Bacik <josef@redhat.com>,
linux-fsdevel@vger.kernel.org, chris.mason@oracle.com,
hch@infradead.org, akpm@linux-foundation.org, npiggin@suse.de,
linux-kernel@vger.kernel.org
Subject: Re: [RFC] new ->perform_write fop
Date: Tue, 18 May 2010 01:35:41 +0200 [thread overview]
Message-ID: <20100517233540.GM3364@quack.suse.cz> (raw)
In-Reply-To: <20100514064145.GJ13617@dastard>
On Fri 14-05-10 16:41:45, Dave Chinner wrote:
...
> Well, the "RESERVE" callout I proposed should mean that the
> allocation that follows the copy should never fail with ENOSPC. i.e.
> if there isn't space, the RESERVE call will fail with ENOSPC, not
> the actual ALLOCATE call that occurs after the data is copied.
>
> Basically I was thinking that in the XFS case, RESERVE would scan the
> range for holes, and reserve all blocks needed to fill all the holes
> in the range. Then the ALLOCATE call would mark them all delalloc.
> The space reservation and delalloc is done in a single call right
> now, but splitting them is not hard...
But this would mean that you would have to implement at least a basic
delayed allocation support for filesystems like ext2, ext3, udf, vfat, etc.
They currently do not have a way to provide a functionality you require
from RESERVE call...
Not that it would be so hard to do - I actually have some patches for
ext2/3 doing that because of problems with ENOSPC during mmaped writes but
it's not completely trivial either.
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
next prev parent reply other threads:[~2010-05-17 23:35 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-12 21:24 [RFC] new ->perform_write fop Josef Bacik
2010-05-13 1:39 ` Josef Bacik
2010-05-13 15:36 ` Christoph Hellwig
2010-05-14 1:00 ` Dave Chinner
2010-05-14 3:30 ` Josef Bacik
2010-05-14 5:50 ` Nick Piggin
2010-05-14 7:20 ` Dave Chinner
2010-05-14 7:33 ` Nick Piggin
2010-05-14 6:41 ` Dave Chinner
2010-05-14 7:22 ` Nick Piggin
2010-05-14 8:38 ` Dave Chinner
2010-05-14 13:33 ` Chris Mason
2010-05-18 6:36 ` Nick Piggin
2010-05-18 8:05 ` Dave Chinner
2010-05-18 10:43 ` Nick Piggin
2010-05-18 12:27 ` Dave Chinner
2010-05-18 15:09 ` Nick Piggin
2010-05-19 23:50 ` Dave Chinner
2010-05-20 6:48 ` Nick Piggin
2010-05-20 20:12 ` Jan Kara
2010-05-20 23:05 ` Dave Chinner
2010-05-21 9:05 ` Steven Whitehouse
2010-05-21 13:50 ` Josef Bacik
2010-05-21 14:23 ` Nick Piggin
2010-05-21 15:19 ` Josef Bacik
2010-05-24 3:29 ` Nick Piggin
2010-05-22 0:31 ` Dave Chinner
2010-05-21 18:58 ` Jan Kara
2010-05-22 0:27 ` Dave Chinner
2010-05-24 9:20 ` Jan Kara
2010-05-24 9:33 ` Nick Piggin
2010-06-05 15:05 ` tytso
2010-06-06 7:59 ` Nick Piggin
2010-05-21 15:15 ` Christoph Hellwig
2010-05-22 2:31 ` Nick Piggin
2010-05-22 8:37 ` Dave Chinner
2010-05-24 3:09 ` Nick Piggin
2010-05-24 5:53 ` Dave Chinner
2010-05-24 6:55 ` Nick Piggin
2010-05-24 10:21 ` Dave Chinner
2010-06-01 6:27 ` Nick Piggin
2010-05-24 18:40 ` Joel Becker
2010-05-17 23:35 ` Jan Kara [this message]
2010-05-18 1:21 ` Dave Chinner
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