Messages in this thread | | | Date | Wed, 11 Sep 2013 16:21:57 +0400 | From | Maxim Patlasov <> | Subject | Re: [PATCH 2/2] fuse: wait for writeback in fuse_file_fallocate() -v2 |
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On 09/11/2013 02:12 PM, Miklos Szeredi wrote: > 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?
Testing updated patch revealed a problem (fsx caught data corruption). Then I instrumented debug version to get a cue. The debug version survived several days of testing, but now I discovered that that test setup was not fully correct. I'll re-run it now.
Thanks, Maxim
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