From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrey Zhadchenko Date: Wed, 12 Aug 2026 23:19:56 +0300 Subject: [Devel] [PATCH VZ10 v2 01/10] drivers/md/dm-qcow2: fix revert_cluster_alloc() for ext_l2 case In-Reply-To: <20260812202005.288994-1-andrey.zhadchenko@virtuozzo.com> References: <20260812202005.288994-1-andrey.zhadchenko@virtuozzo.com> Message-ID: <20260812202005.288994-2-andrey.zhadchenko@virtuozzo.com> List-Id: This function walks over all changed u64 values in md. With ext_l2 half of them holds subcluster description. Firstly it reverts these values to saved pe_page, which is fine, but then it tries to revert r1r2 changes. It makes no sense when the value is a subcluster description. Teach the function to skip subcluster descriptions: do it based on a new lx_level in struct wb_desc. Add new argument to prepare_l_entry_update() and set it there. The warning also could have tripped for ext_l2 entries, so drop it entirely. The function effectively reverts not only cluster alloc, so rename it to revert_l_entries_update() to mimic prepare_l_entries_update. Feature: dm-qcow2: block device over QCOW2 files driver https://virtuozzo.atlassian.net/browse/VSTOR-139406 Signed-off-by: Andrey Zhadchenko --- drivers/md/dm-qcow2-map.c | 28 ++++++++++++++++++---------- drivers/md/dm-qcow2-target.c | 2 +- drivers/md/dm-qcow2.h | 1 + 3 files changed, 20 insertions(+), 11 deletions(-) diff --git a/drivers/md/dm-qcow2-map.c b/drivers/md/dm-qcow2-map.c index db21efb45e17a..2cd8e174049f8 100644 --- a/drivers/md/dm-qcow2-map.c +++ b/drivers/md/dm-qcow2-map.c @@ -1297,18 +1297,19 @@ static void do_md_page_read_complete(int ret, struct qcow2 *qcow2, } /* Be careful with dirty_or_writeback()/etc! Check races. */ -static void revert_clusters_alloc(struct qcow2 *qcow2, struct wb_desc *wbd) +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; int i, ret; + skip_odd = qcow2->ext_l2 && wbd->lx_level == L2_LEVEL; + 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); - WARN_ON_ONCE(!(pos & ~LX_REFCOUNT_EXACTLY_ONE) || - !(pos & LX_REFCOUNT_EXACTLY_ONE)); /* Here we restore prealloced and compressed clu mappings */ pe_page = wbd->pe_page; @@ -1321,6 +1322,9 @@ static void revert_clusters_alloc(struct qcow2 *qcow2, struct wb_desc *wbd) } set_u64_to_be_page(wbd->md->page, i, 0); + if (skip_odd && (i & 1)) + continue; /* pos contains ext_l2 part of L2 entry */ + spin_unlock(&qcow2->md_pages_lock); pos &= ~LX_REFCOUNT_EXACTLY_ONE; @@ -1369,7 +1373,7 @@ static void complete_wbd(struct qcow2 *qcow2, struct wb_desc *wbd) unsigned long flags; spin_lock_irqsave(&qcow2->md_pages_lock, flags); - revert_clusters_alloc(qcow2, wbd); + revert_l_entries_update(qcow2, wbd); clear_writeback_status(qcow2, wbd->md, wbd->ret, &wait_list, &end_list); spin_unlock_irqrestore(&qcow2->md_pages_lock, flags); @@ -2433,7 +2437,7 @@ static loff_t allocate_cluster(struct qcow2 *qcow2, struct qio *qio, #define LU_IGN_CHANGED_IND (1 << 3) static int prepare_l_entry_update(struct qcow2 *qcow2, struct qio *qio, struct md_page *md, u32 index_in_page, - u64 *pval, u32 arg_mask) + u64 *pval, u32 arg_mask, u8 lx_level) { bool wants_pe_page = (arg_mask & LU_WANTS_PE_PAGE); struct wb_desc *new_wbd = NULL; @@ -2453,6 +2457,7 @@ static int prepare_l_entry_update(struct qcow2 *qcow2, struct qio *qio, if (!new_wbd) return -ENOMEM; new_wbd->md = md; + new_wbd->lx_level = lx_level; } else if (wants_pe_page && !md->wbd->pe_page) { pe_page = alloc_page(GFP_NOIO|__GFP_ZERO); if (!pe_page) @@ -2515,7 +2520,8 @@ static int prepare_l1l2_allocation(struct qcow2 *qcow2, struct qio *qio, /* Allocate cluster for L2 entries, and prepare L1 update */ ret = prepare_l_entry_update(qcow2, qio, map->l1.md, map->l1.index_in_page, &val, - LU_SET_ONE_MASK|LU_WANTS_ALLOC); + LU_SET_ONE_MASK|LU_WANTS_ALLOC, + L1_LEVEL); if (ret <= 0) return ret; @@ -2541,7 +2547,8 @@ static int prepare_l1l2_allocation(struct qcow2 *qcow2, struct qio *qio, ret = prepare_l_entry_update(qcow2, qio, map->l2.md, map->l2.index_in_page, - &map->data_clu_pos, arg_mask); + &map->data_clu_pos, arg_mask, + L2_LEVEL); if (ret <= 0) return ret; @@ -2562,7 +2569,7 @@ static int prepare_l1l2_allocation(struct qcow2 *qcow2, struct qio *qio, return prepare_l_entry_update(qcow2, qio, map->l2.md, map->l2.index_in_page + 1, - &val, arg_mask); + &val, arg_mask, L2_LEVEL); } /* @@ -3975,7 +3982,7 @@ static void process_cow_indexes_write(struct qcow2 *qcow2, ret = prepare_l_entry_update(qcow2, qio, lx_md, ext->lx_index_in_page, &ext->allocated_clu_pos, - arg_mask); + arg_mask, ext->cow_level); if (ret < 0) { qio->bi_status = errno_to_blk_status(ret); qio_endio(qio); @@ -3986,7 +3993,8 @@ static void process_cow_indexes_write(struct qcow2 *qcow2, arg_mask &= ~LU_SET_ONE_MASK; ret = prepare_l_entry_update(qcow2, qio, lx_md, ext->lx_index_in_page + 1, - &ext->new_ext_l2, arg_mask); + &ext->new_ext_l2, arg_mask, + L2_LEVEL); WARN_ON_ONCE(ret < 0); } diff --git a/drivers/md/dm-qcow2-target.c b/drivers/md/dm-qcow2-target.c index 3f65897ce9da2..0f1d3e3c5258e 100644 --- a/drivers/md/dm-qcow2-target.c +++ b/drivers/md/dm-qcow2-target.c @@ -174,7 +174,7 @@ void qcow2_flush_deferred_activity(struct qcow2_target *tgt, struct qcow2 *qcow2 int i; /* - * We need second iteration, since revert_clusters_alloc() + * We need second iteration, since revert_l_entries_update() * may start timer again after failed wb. */ for (i = 0; i < 2; i++) { diff --git a/drivers/md/dm-qcow2.h b/drivers/md/dm-qcow2.h index 86f0688e7345a..aa3487007523f 100644 --- a/drivers/md/dm-qcow2.h +++ b/drivers/md/dm-qcow2.h @@ -118,6 +118,7 @@ struct wb_desc { struct list_head dependent_list; int nr_submitted; bool completed; + u8 lx_level; int ret; }; -- 2.43.5