From: Denis V. Lunev <[email protected]> ploop_locate_new_cluster_and_attach_pio() and ploop_process_one_discard_pio() set MD_UPDATING on the BAT page while they prepare its update. A pio that needs the page meanwhile is parked in md->wait_llist by ploop_delay_if_md_busy(), and only ploop_advance_local_after_bat_wb(), at the end of a writeback of the page, gives the parked pios back.
When the update fails, the error path breaks it, clears MD_DIRTY and MD_UPDATING and leaves the parked pios where they are. No writeback of the page is queued, so they are never resubmitted: the writers hang in D state, and after a buffered write every later sync on the host hangs behind them until a reboot. An allocation fails this way when ploop_prepare_bat_update() runs out of memory, when no free cluster is left, or when the punch, zero or preallocation of the new cluster in the top delta fails, e.g. on a write to a read-only device that needs a new cluster. Take the parked pios together with clearing MD_UPDATING, under bat_lock, which every caller of ploop_delay_if_md_busy() holds, and resubmit them with ploop_dispatch_md_waiters(), as the writeback completion does. The error paths of ploop_prepare_reloc_index_wb() and ploop_grow_relocate_cluster() clear MD_UPDATING without a drain too, but they run with pio submission stopped, so nothing is parked there. https://virtuozzo.atlassian.net/browse/VSTOR-154096 Fixes: ddf38fa44df4 ("dm-ploop: fix and rework md updates") Reported-by: Denis Genov <[email protected]> Feature: dm-ploop: ploop target driver Signed-off-by: Denis V. Lunev <[email protected]> --- drivers/md/dm-ploop-map.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c index f0569263622c..b49281691a01 100644 --- a/drivers/md/dm-ploop-map.c +++ b/drivers/md/dm-ploop-map.c @@ -1750,6 +1750,7 @@ static bool ploop_locate_new_cluster_and_attach_pio(struct ploop *ploop, struct pio *pio) { bool bat_update_prepared = false; + struct llist_node *waiters; struct ploop_index_wb *piwb; bool attached = false; u32 page_id; @@ -1818,7 +1819,9 @@ static bool ploop_locate_new_cluster_and_attach_pio(struct ploop *ploop, if (add_to_wblist) clear_bit(MD_DIRTY, &md->status); clear_bit(MD_UPDATING, &md->status); + waiters = llist_del_all(&md->wait_llist); spin_unlock_irqrestore(&ploop->bat_lock, flags); + ploop_dispatch_md_waiters(ploop, waiters); return false; } @@ -2026,6 +2029,7 @@ static void ploop_process_one_discard_pio(struct ploop *ploop, struct pio *pio) { bool bat_update_prepared = false; u32 page_id, clu = pio->clu; + struct llist_node *waiters; struct ploop_index_wb *piwb; struct md_page *md; map_index_t *to; @@ -2092,7 +2096,9 @@ static void ploop_process_one_discard_pio(struct ploop *ploop, struct pio *pio) if (add_to_wblist) clear_bit(MD_DIRTY, &md->status); clear_bit(MD_UPDATING, &md->status); + waiters = llist_del_all(&md->wait_llist); spin_unlock_irqrestore(&ploop->bat_lock, flags); + ploop_dispatch_md_waiters(ploop, waiters); } static inline int ploop_runners_have_pending(struct ploop *ploop) -- 2.53.0 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
