Messages in this thread | | | Date | Thu, 30 Mar 2006 12:01:12 +0200 | From | Jens Axboe <> | Subject | Re: [PATCH][RFC] splice support |
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On Thu, Mar 30 2006, Andrew Morton wrote: > Jens Axboe <axboe@suse.de> wrote: > > > > > The one-at-a-time logic looks OK from a quick scan. Do we have logic in > > > there to check that we're not overrunning i_size? (See the pain > > > do_generic_mapping_read() goes through). > > > > do_splice_to() checks that, should I move that checking further down in > > case the file is truncated? > > Again, see do_generic_mapping_read()'s ghastly tricks - it checks i_size > after each readpage(). > > i_size can increase or decrease under our feet if we're not holding i_mutex > (and we don't want to). So userspace is being silly and the main things we > need to care about here are to not leak uninitialised data and to not oops. > A readpage() outside i_size will return either all-zeroes or some valid > data which isn't actually within i_size any more, so I guess we're OK.
So from the looks of things, worst case is returning zeroes if we 'raced' with someone truncating the file. I'll just leave it as-is for now.
-- Jens Axboe
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