Messages in this thread | | | From | Neil Brown <> | Date | Mon, 3 Apr 2006 11:24:04 +1000 | Subject | Re: [patch 1/1] sys_sync_file_range() |
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On Friday March 31, nathans@sgi.com wrote: > On Thu, Mar 30, 2006 at 06:58:46PM +1100, Neil Brown wrote: > > On Wednesday March 29, akpm@osdl.org wrote: > > > Remove the recently-added LINUX_FADV_ASYNC_WRITE and LINUX_FADV_WRITE_WAIT > > > fadvise() additions, do it in a new sys_sync_file_range() syscall > > > instead. > > > > Hmmm... any chance this could be split into a sys_sync_file_range and > > a vfs_sync_file_range which takes a 'struct file*' and does less (or > > no) sanity checking, so I can call it from nfsd? > > > > Currently I implement COMMIT (which has a range) with a by messing > > around with filemap_fdatawrite and filemap_fdatawait (ignoring the > > range) and I'd rather than a vfs helper. > > I'm not 100% sure, but it looks like the PF_SYNCWRITE process flag > should be set on the nfsd's while they're doing that, which doesn't > seem to be happening atm. Looks like a couple of the IO schedulers > will make use of that knowledge now. All the more reason for a VFS > helper here I guess. ;)
PF_SYNCWRITE? What's that???
(find | xargs grep ...) Oh. The block device schedulers like to know if a request is sync or async (and all reads are assumed to be sync) - which is reasonable - and so have a per-task flag to tell them - which isn't (IMO).
md/raid (particularly raid5) often does the write from a different process than generated the original request, so that will break completely.
What is wrong with a bio flag I wonder....
Hopefully this will get wrapped up in a do_X helper so nfsd won't need to know about it.
Thanks for the heads-up.
NeilBrown
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