Messages in this thread | | | Date | Wed, 11 Sep 2013 12:12:31 +0200 | Subject | Re: [PATCH 2/2] fuse: wait for writeback in fuse_file_fallocate() -v2 | From | Miklos Szeredi <> |
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On Fri, Aug 30, 2013 at 1:33 PM, Maxim Patlasov <mpatlasov@parallels.com> wrote: > 08/30/2013 01:13 PM, Miklos Szeredi пишет: > >> On Thu, Aug 29, 2013 at 6:41 PM, Miklos Szeredi <miklos@szeredi.hu> wrote: >>> >>> BTW, isn't it enough to do the filemap_write_and_wait() *plus* the >>> fuse_set_nowrite()? >> >> Thought about it a bit and I think this should do fine. >> >> Any writes before the fallocate will go trough before the fallocate. >> i_mutex guarantees that only one instance of fuse_set_nowrite() is >> running. Any mmaped writes during the fallocate() will go after the >> fallocate request and the page cache truncation and that's fine too. >> Page cache is consistent since it doens't contain pages for those >> writes to the hole. Subsequent reads to that area will fill them in. >> >> Any other concerns? > > > No. What you suggest looks as a neat and correct solution. I'll resend the > updated patch after some testing (since now till Monday). > > As for proof-of-correctness, all you wrote above is correct, but the first > point had been boiling my mind for a while. I came to the following > reasoning (hopefully it is what you meant): > > The fact that filemap_write_and_wait() returned infers that > end_page_writeback() was called for all relevant pages. And fuse doesn't > call it before adding request to fi->queued_writes and calling > fuse_flush_writepages(). And the latter, in turn, guarantees proper > accounting of request in fi->writectr. Here, of course, it's crucial that we > can't have concurrent fuse_set_nowrite(), as you explained. Hence, so far as > fi->writectr was bumped, fuse_set_nowrite() we call after > filemap_write_and_wait() would wait until all changes have gone to the > server.
Any news about this?
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