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Date: Wed, 22 Oct 2025 10:01:10 +0200
From: Christoph Hellwig <hch@lst.de>
To: Kanchan Joshi <joshi.k@samsung.com>
Cc: Christoph Hellwig <hch@lst.de>, kbusch@kernel.org, axboe@kernel.dk,
	brauner@kernel.org, josef@toxicpanda.com, jack@suse.cz,
	jlayton@kernel.org, linux-fsdevel@vger.kernel.org,
	linux-block@vger.kernel.org
Subject: Re: [RFC PATCH 2/5] fs: add the interface to query user write
 streams
Message-ID: <20251022080110.GA9997@lst.de>
References: <20250729145135.12463-1-joshi.k@samsung.com> <CGME20250729145335epcas5p462315e4dae631a1d940b6c3b2b611659@epcas5p4.samsung.com> <20250729145135.12463-3-joshi.k@samsung.com> <20250812082240.GB22212@lst.de> <4cf4ebdd-a33f-4ff5-8016-aff8a6a87c54@samsung.com>
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On Thu, Oct 16, 2025 at 03:27:22PM +0530, Kanchan Joshi wrote:
> On 8/12/2025 1:52 PM, Christoph Hellwig wrote:
> > On Tue, Jul 29, 2025 at 08:21:32PM +0530, Kanchan Joshi wrote:
> >> Add new fcntl F_GET_MAX_WRITE_STREAMS.
> >> This returns the numbers of streams that are available for userspace.
> >>
> >> And for that, use ->user_write_streams() callback when the involved
> >> filesystem provides it.
> >> In absence of such callback, use 'max_write_streams' queue limit of the
> >> underlying block device.
> > As mentioned in patch 1, I think we'd rather dispath the whole fcntl
> > to the file system, and then use generic helpers, which will give
> > more control of the details to the file system.
> 
> 
> I could not follow it, can you please expand that a bit.
> Should I get F_GET_MAX_WRITE_STREAMS dispatched to new inode operation.

Handle all of F_GET_MAX_WRITE_STREAMS in the file system and add a new
file operation for it.