place_r2() links a new refblock into R1, but moves neither file_size nor file_preallocated_area_start. The refblock stays at or above the watermark if truncate_prealloc_safe() in allocate_cluster() fails after place_r2(), or if a parallel mark_cluster_unused() lowers free_cluster_search_pos before the second pass of find_unused_cluster(). Truncation of preallocations on suspend then cuts the file under the refblock: R1 on disk points past EOF, and the next session gets -EIO on allocations in the range it covers.
Make find_unused_cluster() report a position not covered by R2 instead of placing the refblock there itself. allocate_cluster() prepares that cluster the same way as a data cluster, with the punch, extend and watermark update moved into prepare_unused_cluster(), and calls place_r2() before searching again. 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 | 88 ++++++++++++++++++++++----------------- 1 file changed, 50 insertions(+), 38 deletions(-) diff --git a/drivers/md/dm-qcow2-map.c b/drivers/md/dm-qcow2-map.c index 34d9d9810f60..e8a41954c4c6 100644 --- a/drivers/md/dm-qcow2-map.c +++ b/drivers/md/dm-qcow2-map.c @@ -2083,21 +2083,12 @@ static int parse_metadata(struct qcow2 *qcow2, struct qio **qio, * and connects it to R1 table entry. */ static int place_r2(struct qcow2 *qcow2, struct qcow2_map_item *r1, - struct qcow2_map_item *r2, loff_t r2_pos, struct qio **qio) + struct qcow2_map_item *r2, loff_t r2_pos) { struct dm_target *ti = qcow2->tgt->ti; u64 page_id = r2_pos >> PAGE_SHIFT; int ret; - if (delay_if_writeback(qcow2, r1->md, r1->index_in_page, qio, true)) - return 0; - - ret = qcow2_punch_hole(qcow2->file, r2_pos, qcow2->clu_size); - if (ret) { - QC_ERR(ti, "punch hole: %d", ret); - return ret; - } - ret = qcow2_alloc_and_insert_md_page(qcow2, page_id, &r2->md); if (ret < 0) { QC_ERR(ti, "Can't alloc: ret=%d, page_id=%llu", ret, page_id); @@ -2113,7 +2104,7 @@ static int place_r2(struct qcow2 *qcow2, struct qcow2_map_item *r1, spin_unlock_irq(&qcow2->md_pages_lock); mark_cluster_used(qcow2, r2->md, r2->index_in_page); - return 1; + return 0; } static s32 find_unused_block_entry(struct qcow2 *qcow2, struct md_page *md, @@ -2135,11 +2126,13 @@ static s32 find_unused_block_entry(struct qcow2 *qcow2, struct md_page *md, static loff_t find_unused_cluster(struct qcow2 *qcow2, struct qio **qio, struct qcow2_map_item *r1, - struct qcow2_map_item *r2) + struct qcow2_map_item *r2, bool *needs_r2) { u32 clu_size = qcow2->clu_size; s32 index, ret; loff_t pos; + + *needs_r2 = false; again: pos = READ_ONCE(qcow2->free_cluster_search_pos); if (pos >= qcow2->reftable_max_file_size) @@ -2151,15 +2144,15 @@ static loff_t find_unused_cluster(struct qcow2 *qcow2, struct qio **qio, return ret; /* * Since pos is not covered by R2, the whole cluster - * must be unused. Use it to store R2 cluster. + * must be unused. The caller stores R2 cluster there. * Both indexes must be 0 here, because of we allocate * clusters from small to big. */ WARN_ON_ONCE(r2->index_in_page != 0 || r2->index != 0); - ret = place_r2(qcow2, r1, r2, pos, qio); - if (ret <= 0) - return ret; - goto again; + if (delay_if_writeback(qcow2, r1->md, r1->index_in_page, qio, true)) + return 0; + *needs_r2 = true; + return pos; } spin_lock_irq(&qcow2->md_pages_lock); @@ -2436,6 +2429,37 @@ static int relocate_refcount_table(struct qcow2 *qcow2, struct qio **qio) return -EIO; } +/* + * Zero the unused cluster at @pos and make the file size and + * file_preallocated_area_start cover it. + */ +static int prepare_unused_cluster(struct qcow2 *qcow2, loff_t pos) +{ + loff_t off, end = pos + qcow2->clu_size; + loff_t old_size = qcow2->file_size; + int ret; + + if (pos < qcow2->file_preallocated_area_start) { + /* Clu at @pos may contain dirty data */ + off = min_t(loff_t, old_size, end); + ret = qcow2_punch_hole(qcow2->file, pos, off - pos); + if (ret) { + QC_ERR(qcow2->tgt->ti, "punch hole: %d", ret); + return ret; + } + } + + if (end > old_size) { + ret = truncate_prealloc_safe(qcow2, end, __func__); + if (ret) + return ret; + } + + if (end > qcow2->file_preallocated_area_start) + qcow2->file_preallocated_area_start = end; + return 0; +} + /* * This function is aimed to be called only from main work. * In case of wish to use it from more places, it's needed @@ -2445,13 +2469,12 @@ static int relocate_refcount_table(struct qcow2 *qcow2, struct qio **qio) static loff_t allocate_cluster(struct qcow2 *qcow2, struct qio *qio, struct md_page **r2_md, u32 *r2_index_in_page) { - u32 clu_size = qcow2->clu_size; - struct file *file = qcow2->file; - loff_t pos, off, end, old_size; struct qcow2_map_item r1, r2; + bool needs_r2; + loff_t pos; int ret; again: - pos = find_unused_cluster(qcow2, &qio, &r1, &r2); + pos = find_unused_cluster(qcow2, &qio, &r1, &r2, &needs_r2); if (unlikely(pos == -ENOENT)) { ret = relocate_refcount_table(qcow2, &qio); if (ret <= 0) @@ -2461,28 +2484,17 @@ static loff_t allocate_cluster(struct qcow2 *qcow2, struct qio *qio, if (pos <= 0) return pos; - end = pos + clu_size; - old_size = qcow2->file_size; - - if (pos < qcow2->file_preallocated_area_start) { - /* Clu at @pos may contain dirty data */ - off = min_t(loff_t, old_size, end); - ret = qcow2_punch_hole(file, pos, off - pos); - if (ret) { - QC_ERR(qcow2->tgt->ti, "punch hole: %d", ret); - return ret; - } - } + ret = prepare_unused_cluster(qcow2, pos); + if (ret) + return ret; - if (end > old_size) { - ret = truncate_prealloc_safe(qcow2, end, __func__); + if (needs_r2) { + ret = place_r2(qcow2, &r1, &r2, pos); if (ret) return ret; + goto again; } - if (end > qcow2->file_preallocated_area_start) - qcow2->file_preallocated_area_start = end; - mark_cluster_used(qcow2, r2.md, r2.index_in_page); if (r2_md) *r2_md = r2.md; -- 2.53.0 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
