Re: algif_hash: splice of data > 2**16

[leroy christophe]

Le 20/12/2014 07:37, Stephan Mueller a écrit :
> Am Donnerstag, 18. Dezember 2014, 13:22:20 schrieb leroy christophe:
>
> Hi Christophe,
>
> > Le 18/12/2014 13:15, Stephan Mueller a écrit :
> > > Hi Herbert,
> > >
> > > While testing the vmsplice/splice interface of algif_hash I was made
> > > aware of the problem that data blobs larger than 16 pages do not seem to
> > > be hashed properly.
> > >
> > > For testing, a file is mmap()ed and handed to vmsplice / splice. If the
> > > file is smaller than 2**16, the interface returns the proper hash.
> > > However, when the file is larger, only the first 2**16 bytes seem to be
> > > used.
> > >
> > > When adding printk's to hash_sendpage, I see that this function is
> > > invoked exactly 16 times where the first 15 invocations have the
> > > MSG_MORE flag set and the last invocation does not have MSG_MORE.
> > Hi Stephan,
> >
> > I have already noticed the same issue and proposed a patch, but I never
> > got any feedback and it has never been merged, allthought I pinged it a
> > few times.
> >
> > See https://lkml.org/lkml/2014/4/18/276
> After testing, this patch does not work for me. The operation still stops
> after 16 pages.
Yes, it looks like the function I fixed is exclusively used by 
sendfile() system call.
So there is probably the same kind of fix to be done in another function.

Christophe

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