Maxim Patlasov <mpatla...@openvz.org> writes:
> kaio_submit_alloc() sometimes piggybacks ploop request with additional work: > set preq->prealloc_size, pass preq to fsync_thread, perform preallocation > there, get it back to kaio_submit_alloc(), move preallocation from > preq->prealloc_size to io->prealloced_size. > > The problem happens when such a request does not get back to > kaio_submit_alloc. > For example, it may happen if ploop shrink or compact is in progress: by the > time the request is re-scheduled after preallocation, free blocks emerges, > and ploop_entry_request() use one of them calling kaio_submit intead of > kaio_submit_alloc. > > To solve this case and other similar ones, the patch moves the code > transferring preq->prealloc_size to ploop_req_state_process(). Now, this > transfer will be done independently on how ploop state machine decides to > handle that preq. > > https://jira.sw.ru/browse/PSBM-35095 ACK > --- > drivers/block/ploop/dev.c | 13 +++++++++++++ > drivers/block/ploop/io_kaio.c | 9 +-------- > 2 files changed, 14 insertions(+), 8 deletions(-) > kaio_submit_alloc() sometimes piggybacks ploop request with additional work: > set preq->prealloc_size, pass preq to fsync_thread, perform preallocation > there, get it back to kaio_submit_alloc(), move preallocation from > preq->prealloc_size to io->prealloced_size. > > The problem happens when such a request does not get back to > kaio_submit_alloc. > For example, it may happen if ploop shrink or compact is in progress: by the > time the request is re-scheduled after preallocation, free blocks emerges, > and ploop_entry_request() use one of them calling kaio_submit intead of > kaio_submit_alloc. > > To solve this case and other similar ones, the patch moves the code > transferring preq->prealloc_size to ploop_req_state_process(). Now, this > transfer will be done independently on how ploop state machine decides to > handle that preq. > > https://jira.sw.ru/browse/PSBM-35095 > --- > drivers/block/ploop/dev.c | 13 +++++++++++++ > drivers/block/ploop/io_kaio.c | 9 +-------- > 2 files changed, 14 insertions(+), 8 deletions(-) > > diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c > index 30eb8a7..97e75a7 100644 > --- a/drivers/block/ploop/dev.c > +++ b/drivers/block/ploop/dev.c > @@ -2275,6 +2275,19 @@ static void ploop_req_state_process(struct > ploop_request * preq) > ploop_tracker_notify(plo, sec); > } > > + /* trick: preq->prealloc_size is actually new pos of eof */ > + if (unlikely(preq->prealloc_size && !preq->error)) { > + struct ploop_io *io = &ploop_top_delta(plo)->io; > + int log = preq->plo->cluster_log + 9; > + > + BUG_ON(preq != io->prealloc_preq); > + io->prealloc_preq = NULL; > + > + io->prealloced_size = preq->prealloc_size - > + ((loff_t)io->alloc_head << log); > + preq->prealloc_size = 0; /* only for sanity */ > + } > + > restart: > __TRACE("ST %p %u %lu\n", preq, preq->req_cluster, preq->eng_state); > switch (preq->eng_state) { > diff --git a/drivers/block/ploop/io_kaio.c b/drivers/block/ploop/io_kaio.c > index ccdf1f4..db900a3 100644 > --- a/drivers/block/ploop/io_kaio.c > +++ b/drivers/block/ploop/io_kaio.c > @@ -460,14 +460,7 @@ kaio_submit_alloc(struct ploop_io *io, struct > ploop_request * preq, > return; > } > > - /* trick: preq->prealloc_size is actually new pos of eof */ > - if (unlikely(preq->prealloc_size)) { > - BUG_ON(preq != io->prealloc_preq); > - io->prealloc_preq = NULL; > - > - io->prealloced_size = preq->prealloc_size - ((loff_t)iblk << > log); > - preq->prealloc_size = 0; /* only for sanity */ > - } > + BUG_ON(preq->prealloc_size); > > if (unlikely(io->prealloced_size < clu_siz)) { > if (!io->prealloc_preq) {
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