Richard W.M. Jones wrote: > On Thu, Apr 02, 2009 at 05:44:07PM -0500, Eric Sandeen wrote: >> James Ralston wrote: >> >>> I intend to start filing bugs against anything I can find that doesn't >>> use fallocate(), yes. But I needed a better implementation to suggest >>> than posix_fallocate(). >> Cool. Feel free to cc: me on them? >> >> FWIW transmission already can do it though it requires some >> undocumented(?) configuration. >> >> It also gives you the choice of posix_fallocate(), or not. It'd be >> nice if you could say "fallocate if you've got it; but no >> posix_fallocate, thanks" > > I just wrote a new program that uses posix_fallocate to allocate large > files (of zeroes). Should I change it to use fallocate? What's the > recommended code snippet / autoconf configuration? Good question, it'd be nice to have some canned recipe for this... but TBH I'm no autoconf expert. The downside of posix_fallocate is that it will fall back to explicit zero-writing if the filesystem (or the kernel) doesn't support sys_fallocate - and you won't know the difference, if you care ... To call the syscall directly when glibc doesn't have fallocate(2) it's something like: error = syscall(SYS_fallocate, fd, falloc_mode, offset, length); (modulo the vagaries of syscalls on some architectures) and for fallocate(2) it's: error = fallocate(fd, falloc_mode, offset, length); but you probably meant a code snippet & autoconf magic for navigating the possible calls available at any given time... :) -Eric > Rich. > -- fedora-devel-list mailing list fedora-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-devel-list
