Messages in this thread | | | Date | Mon, 25 Apr 2011 06:37:37 -0600 | From | Eric Blake <> | Subject | Re: [PATCH 1/2] fs: add SEEK_HOLE and SEEK_DATA flags |
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On 04/24/2011 11:49 AM, Jamie Lokier wrote: >> My problem with FIND_* is that we are messing with the well understood >> semantics of lseek(). > > fcntl() looks a better fit for FIND_HOLE/DATA anyway.
With fcntl(), it would have to be something like:
off_t offset = start; if (fcntl (fd, F_FIND_HOLE, &offset) != 0) ; // find failed // offset is now set to the next location after start
That is, offset has to be passed as an input _and_ output parameter, since we can't use the int return value of fcntl to convey off_t information, and since the optional third argument of fcntl has traditionally been no wider than a pointer which is not the case for off_t on 32-bit platforms.
-- Eric Blake eblake@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org
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