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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <3989572.1734546794@warthog.procyon.org.uk> References: <3989572.1734546794@warthog.procyon.org.uk> Cc: dhowells@redhat.com, Alex Markuze , Viacheslav Dubeyko , Ilya Dryomov , Xiubo Li , Jeff Layton , ceph-devel@vger.kernel.org, netfs@lists.linux.dev, linux-fsdevel@vger.kernel.org Subject: Re: Ceph and Netfslib Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <3991937.1734550983.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Wed, 18 Dec 2024 19:43:03 +0000 Message-ID: <3991938.1734550983@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 David Howells wrote: > = > I don't know whether you know, but I'm working on netfslib-ising ceph wi= th an > eye to moving all the VFS/VM normal I/O interfaces to netfslib (->read_i= ter, > ->write_iter, ->readahead, ->read_folio, ->page_mkwrite, ->writepages), = though > with wrapping/methods by which each network filesystem can add its own > distinctive flavour. > = > Also, that would include doing things like content encryption, since tha= t is > generally useful in filesystems and I have plans to support it in both A= FS and > CIFS as well. I should also mention that netfslib brings multipage folio support with it too. All the filesystem has to do is to flip the bit: mapping_set_large_folios(inode->i_mapping); On reading, netfs will tile subrequests drawn from both the server and the local cache across a sequence of multipage folios. On writing, it will wr= ite the data in parallel to both the server and the local cache, tiling subrequests for both separately across the folios to be written. Subrequests don't have to match folios in size or alignment and nor, when writing, do subrequests going to the server have to match subrequests goin= g to the local cache. Whilst on writing it only permits two parallel streams - one to the server= and one to the cache - this is just an array with a hard-coded size at the mom= ent and could made expandable later to allow simultaneous writing to multiple servers with different I/O characteristics. David