Messages in this thread | | | Date | Thu, 30 Jul 2020 01:05:44 +0100 | From | Al Viro <> | Subject | Re: [PATCH 22/23] fs: default to generic_file_splice_read for files having ->read_iter |
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On Tue, Jul 07, 2020 at 07:48:00PM +0200, Christoph Hellwig wrote: > If a file implements the ->read_iter method, the iter based splice read > works and is always preferred over the ->read based one. Use it by > default in do_splice_to and remove all the direct assignment of > generic_file_splice_read to file_operations.
The worst problem here is the assumption that all ->read_iter() instances will take pipe-backed destination; that's _not_ automatically true. In particular, it's almost certainly false for tap_read_iter() (as well as tun_chr_read_iter() in IFF_VNET_HDR case).
Other potentially interesting cases: cuse and hugetlbfs.
But in any case, that blind assertion ("iter based splice read works") really needs to be backed by something.
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