A failed L1/L2 writeback reverts the page in memory and frees each cluster allocated for it: revert_l_entries_update() drops the refcount of a newly allocated cluster, and a COW qio waiting on the page frees its cluster through FREE_ALLOCATED_CLU when it ends with the error. The write may still have partially reached the disk, so L1/L2 on disk may point to such a cluster. Until the page is rewritten, the allocator may give the cluster to another offset, and two guest offsets then share it. If the page is not rewritten before suspend, the image is left with a reference to a free cluster.
Keep the refcount of these clusters instead. If L1/L2 on disk points to such a cluster, the image stays consistent; otherwise the cluster is leaked, which check repairs by freeing it. So the image needs no check and resume needs no refusal. https://virtuozzo.atlassian.net/browse/VSTOR-148171 Feature: dm-qcow2: block device over QCOW2 files driver Fixes: 222b6f1291c1c ("dm-qcow2: Introduce driver to create block devices over QCOW2 files") Signed-off-by: Alexander Ivanov <[email protected]> --- drivers/md/dm-qcow2-map.c | 51 +++++++----------------------------- drivers/md/dm-qcow2-target.c | 4 --- 2 files changed, 9 insertions(+), 46 deletions(-) diff --git a/drivers/md/dm-qcow2-map.c b/drivers/md/dm-qcow2-map.c index 995f611ae5bb..4ab8051f08c4 100644 --- a/drivers/md/dm-qcow2-map.c +++ b/drivers/md/dm-qcow2-map.c @@ -1331,50 +1331,15 @@ static void do_md_page_read_complete(int ret, struct qcow2 *qcow2, /* Be careful with dirty_or_writeback()/etc! Check races. */ static void revert_l_entries_update(struct qcow2 *qcow2, struct wb_desc *wbd) { - struct qcow2_map_item r1, r2; - struct page *pe_page; - bool skip_odd; - u64 pos, old; - bool cleared; - int i, ret; - - skip_odd = qcow2->ext_l2 && wbd->lx_level == L2_LEVEL; + struct page *pe_page = wbd->pe_page; + u64 old; + int i; lockdep_assert_held(&qcow2->md_pages_lock); for_each_set_bit(i, wbd->changed_indexes, LX_INDEXES_PER_PAGE) { - pos = get_u64_from_be_page(wbd->md->page, i); - - cleared = !(pos & ~(u64)L2_READS_ALL_ZEROES); - /* Here we restore prealloced and compressed clu mappings */ - pe_page = wbd->pe_page; - if (pe_page) { /* Only L2 has this. */ - old = get_u64_from_be_page(pe_page, i); - if (old != 0) { - set_u64_to_be_page(wbd->md->page, i, old); - continue; /* Avoid mark_cluster_unused() */ - } - } - - set_u64_to_be_page(wbd->md->page, i, 0); - if (skip_odd && (i & 1)) - continue; /* pos contains ext_l2 part of L2 entry */ - if (cleared) - continue; /* no cluster was allocated */ - - spin_unlock(&qcow2->md_pages_lock); - pos &= ~LX_REFCOUNT_EXACTLY_ONE; - - /* - * R1/R2 should be cached, since we was able - * to submit cluster allocation. - */ - ret = qcow2_handle_r1r2_maps(qcow2, pos, NULL, &r1, &r2, false); - if (WARN_ON_ONCE(ret <= 0)) - continue; - - mark_cluster_unused(qcow2, r2.md, r2.index_in_page, pos); - spin_lock(&qcow2->md_pages_lock); + old = pe_page ? get_u64_from_be_page(pe_page, i) : 0; + set_u64_to_be_page(wbd->md->page, i, old); } } @@ -1408,6 +1373,7 @@ static void complete_wbd(struct qcow2 *qcow2, struct wb_desc *wbd) LIST_HEAD(wait_list); LIST_HEAD(end_list); unsigned long flags; + struct qio *qio; spin_lock_irqsave(&qcow2->md_pages_lock, flags); revert_l_entries_update(qcow2, wbd); @@ -1415,6 +1381,8 @@ static void complete_wbd(struct qcow2 *qcow2, struct wb_desc *wbd) &wait_list, &end_list); spin_unlock_irqrestore(&qcow2->md_pages_lock, flags); + list_for_each_entry(qio, &end_list, link) + qio->ext->cleanup_mask &= ~FREE_ALLOCATED_CLU; qcow2_dispatch_qios(qcow2, NULL, &wait_list); end_qios(&end_list, errno_to_blk_status(wbd->ret)); } @@ -1445,8 +1413,7 @@ static void do_md_page_write_complete(int ret, struct qcow2 *qcow2, /* * We can finish wb only in case of success. * Otherwise this is done in finalize_wbd() - * after data qios stopped use wbd clusters - * and clusters allocations reverted. + * after data qios stopped use wbd clusters. */ if (likely(ret == 0)) { clear_writeback_status(qcow2, md, ret, diff --git a/drivers/md/dm-qcow2-target.c b/drivers/md/dm-qcow2-target.c index 6824d95193ae..99fb68a5535e 100644 --- a/drivers/md/dm-qcow2-target.c +++ b/drivers/md/dm-qcow2-target.c @@ -173,10 +173,6 @@ void qcow2_flush_deferred_activity(struct qcow2_target *tgt, struct qcow2 *qcow2 struct md_page *md; int i; - /* - * We need second iteration, since revert_l_entries_update() - * may start timer again after failed wb. - */ for (i = 0; i < 2; i++) { if (timer_delete_sync_try(&qcow2->slow_wb_timer) != -1) qcow2_slow_wb_timer_fn(&qcow2->slow_wb_timer); -- 2.53.0 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
