On Tue, Sep 30, 2014 at 4:53 PM, Zach Brown <zab@xxxxxxxxx> wrote: > On Tue, Sep 30, 2014 at 12:48:45PM +0200, Jan Kara wrote: >> On Tue 30-09-14 10:11:32, Thanos Makatos wrote: >> > >> > Regarding extending the ioctl to invalidate the page cache, do you have >> > any suggestions where I could start looking? >> You just need to call invalidate_inode_pages2(). That is going to do all >> you need. >> >> > Would such a new ioctl have any chance to be accepted upstream? >> I believe a possibility for a file to be fully flushed from page cache is >> useful at times and if you present well your usecase there are reasonable >> chances it will get accepted upstream. > > Agreed, this seems reasonable. How many times have we all dropped our > entire cache just 'cause we didn't have a more precise tool? > > $ grep -ri drop_caches xfstests/ > xfstests/src/fsync-tester.c: if ((fd = open("/proc/sys/vm/drop_caches", O_WRONLY)) < 0) { > xfstests/src/stale_handle.c: system("echo 3 > /proc/sys/vm/drop_caches"); > xfstests/common/quota: echo 3 > /proc/sys/vm/drop_caches > > The last one even says: > > # XXX: really need an ioctl instead of this big hammer > echo 3 > /proc/sys/vm/drop_caches > > :) > It would definitely be useful for NFS, however we'd want the option of clearing the cached metadata too (acls, mode bits, owner/group owner, etc.) -- Trond Myklebust Linux NFS client maintainer, PrimaryData trond.myklebust@xxxxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html