From: Dmitry Monakhov <dmonakhov@openvz.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
viro@zeniv.linux.org.uk, hch@infradead.org
Subject: Re: [PATCH 2/4] fs: add fadvise file_operation
Date: Tue, 21 Oct 2014 12:31:26 +0400 [thread overview]
Message-ID: <87iojdygbl.fsf@openvz.org> (raw)
In-Reply-To: <20141019145138.GB9593@infradead.org>
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Christoph Hellwig <hch@infradead.org> writes:
> On Sat, Oct 18, 2014 at 07:21:26PM +0400, Dmitry Monakhov wrote:
>> sys_fadvise result in direct f_mode modification, which may be not
>> suitable for some unusual filesytems where file mode invariant is more
>> complex. In order to support such filesystems we have to delegate fadvise
>> logic to filesystem layer.
>
> Is there a real use case for it? So for it seems mostly about ecryptfs,
> and even that use is lacking a proper explanation.
Fairly to say original issue was with vzfs (COW stack filesystem for
containers from openvz). As far as I understand direct analog is
unionfs. We asserted v_file->mode == lower_file->f_mode, but
fadvise (POSIX_FADV_{RANDOM,RANDOM,SEQUENTIAL})changes v_file->mode directly.
>
> Also fadvice and set_flags seem entirely unrelated, I don't understand
> why you're throwing fadvice in thise series.
It has semantic relation. Both methods manipulate filp->XXX internals directly
No problem I can split this to separate patch set.
>
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next prev parent reply other threads:[~2014-10-21 8:31 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-18 15:21 [PATCH 0/4] fs: fcntl/fadvice fixes v2 Dmitry Monakhov
2014-10-18 15:21 ` [PATCH 1/4] fs: fcntl add set_flags wrapper -v2 Dmitry Monakhov
2014-10-18 15:21 ` [PATCH 2/4] fs: add fadvise file_operation Dmitry Monakhov
2014-10-19 14:51 ` Christoph Hellwig
2014-10-21 8:31 ` Dmitry Monakhov [this message]
2014-10-18 15:21 ` [PATCH 3/4] ecryptfs: add fadvise/set_flags calbacks Dmitry Monakhov
2014-10-19 14:50 ` Christoph Hellwig
2014-10-18 15:21 ` [PATCH 4/4] cifs: add set_flag callback Dmitry Monakhov
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