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From:   David Howells <dhowells@redhat.com>
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        linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
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Subject: Re: How to convert I/O iterators to iterators, sglists and RDMA lists
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Date:   Fri, 04 Nov 2022 18:47:23 +0000
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David Howells <dhowells@redhat.com> wrote:

> > What protects pages involved in ITER_XARRAY iterator created by
> > afs_read_dir()?  Note that we are not guaranteed inode_lock() on
> > the directory in question...
> =

> Yeah - that needs fixing.  The size of the data can change, but I don't =
update
> the iterator.

Actually, no.  The iterator is the output buffer for afs_fetch_data().  If=
 the
buffer turned out to be too small we drop the validate_lock and go round a=
nd
try again.

req->actual_len and req->file_size are updated by afs_fetch_data() from th=
e
RPC reply.  req->len tells the RPC delivery code how big the buffer is (wh=
ich
we don't have to fill if there's less data available than we have buffer
space).

David