dm-qcow2 is almost ready to merge intermediate images, thanks to separated metadata tables and qio being per-qcow2. So this patch mostly propagates which qcow2 we want to use instead of tgt->top.
qcow2_merge_backward_complete is a bit harder due to in-middle replacement and needing to recalculate img_id for a part of image chain. https://virtuozzo.atlassian.net/browse/VSTOR-101375 Signed-off-by: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com> --- v2: - changed depth to u32 - reverted changes in set_backward_merge_in_process(): do queue stop for not top qcow2 images at it's own level - changed saving qcow2 in backward_merge to saving pointer to the qcow2 which we later intend to change to lower delta drivers/md/dm-qcow2-cmd.c | 58 ++++++++++++++++++++++++++++----------- drivers/md/dm-qcow2.h | 1 + 2 files changed, 43 insertions(+), 16 deletions(-) diff --git a/drivers/md/dm-qcow2-cmd.c b/drivers/md/dm-qcow2-cmd.c index e77052ad61e6b..64bf282893e34 100644 --- a/drivers/md/dm-qcow2-cmd.c +++ b/drivers/md/dm-qcow2-cmd.c @@ -116,9 +116,9 @@ static int qcow2_service_iter(struct qcow2_target *tgt, struct qcow2 *qcow2, } ALLOW_ERROR_INJECTION(qcow2_service_iter, ERRNO); -static int qcow2_merge_common(struct qcow2_target *tgt) +static int qcow2_merge_common(struct qcow2_target *tgt, struct qcow2 *qcow2) { - struct qcow2 *qcow2 = tgt->top, *lower = qcow2->lower; + struct qcow2 *lower = qcow2->lower; u32 clu_size = qcow2->clu_size; loff_t end = lower->hdr.size; @@ -139,9 +139,8 @@ static int qcow2_merge_forward(struct qcow2_target *tgt) } ALLOW_ERROR_INJECTION(qcow2_merge_forward, ERRNO); -static int qcow2_break_l1cow(struct qcow2_target *tgt) +static int qcow2_break_l1cow(struct qcow2_target *tgt, struct qcow2 *qcow2) { - struct qcow2 *qcow2 = tgt->top; loff_t end = qcow2->hdr.size; loff_t step = (u64)qcow2->l2_entries * qcow2->clu_size; @@ -154,6 +153,15 @@ static void set_backward_merge_in_process(struct qcow2_target *tgt, { LIST_HEAD(list); + /* + * There are no writes if it is not the top qcow2 image. + * so we do not need to stop and flush requests when setting + */ + if (qcow2 != tgt->top && set) { + qcow2->backward_merge_in_process = set; + return; + } + /* * To avoid race between allocations and COWS * we completely stop queueing qios and wait @@ -240,11 +248,17 @@ static int qcow2_merge_backward_progress(struct qcow2_target *tgt, static int qcow2_merge_backward_set_eventfd(struct qcow2_target *tgt, int efd); -static int qcow2_merge_backward_start(struct qcow2_target *tgt, int efd) +static int qcow2_merge_backward_start(struct qcow2_target *tgt, int efd, u32 depth) { - struct qcow2 *qcow2 = tgt->top, *lower = qcow2->lower; + struct qcow2 *qcow2 = tgt->top, *lower, **pqcow2 = &tgt->top; int ret; + while (depth-- && qcow2->lower) { + pqcow2 = &qcow2->lower; + qcow2 = qcow2->lower; + } + lower = qcow2->lower; + lockdep_assert_held(&tgt->ctl_mutex); if (!lower) @@ -263,6 +277,7 @@ static int qcow2_merge_backward_start(struct qcow2_target *tgt, int efd) if (ret) return ret; + tgt->backward_merge.pqcow2 = pqcow2; tgt->backward_merge.state = BACKWARD_MERGE_START; __backward_merge_update_stage(tgt, BACKWARD_MERGE_STAGE_START); tgt->backward_merge.error = 0; @@ -291,7 +306,7 @@ void qcow2_merge_backward_work(struct work_struct *work) __backward_merge_update_stage(tgt, BACKWARD_MERGE_STAGE_BREAK_L1COW); mutex_unlock(&tgt->ctl_mutex); - qcow2 = tgt->top; + qcow2 = *tgt->backward_merge.pqcow2; lower = qcow2->lower; /* @@ -300,7 +315,7 @@ void qcow2_merge_backward_work(struct work_struct *work) * we'd have to freeze IO going to all data clusters * under every L1 entry related to several snapshots. */ - ret = qcow2_break_l1cow(tgt); + ret = qcow2_break_l1cow(tgt, qcow2); if (ret) { QC_ERR(tgt->ti, "Can't break L1 COW"); goto out_err; @@ -316,7 +331,7 @@ void qcow2_merge_backward_work(struct work_struct *work) /* Start merge */ backward_merge_update_stage(tgt, BACKWARD_MERGE_STAGE_RUNNING); - ret = qcow2_merge_common(tgt); + ret = qcow2_merge_common(tgt, qcow2); if (ret) { set_backward_merge_in_process(tgt, qcow2, false); ret2 = qcow2_set_image_file_features(lower, false); @@ -350,16 +365,23 @@ void qcow2_merge_backward_work(struct work_struct *work) static int qcow2_merge_backward_complete(struct qcow2_target *tgt) { - struct qcow2 *qcow2 = tgt->top, *lower = qcow2->lower; + struct qcow2 *qcow2 = *tgt->backward_merge.pqcow2, *i; int ret; lockdep_assert_held(&tgt->ctl_mutex); if (tgt->backward_merge.state != BACKWARD_MERGE_WAIT_COMPLETION) return -EBUSY; + + *tgt->backward_merge.pqcow2 = qcow2->lower; + + i = tgt->top; + while (i != qcow2->lower) { + i->img_id--; + i = i->lower; + } + __backward_merge_update_stage(tgt, BACKWARD_MERGE_STAGE_COMPLETING); - - tgt->top = lower; smp_wmb(); /* Pairs with qcow2_ref_inc() */ qcow2_inflight_ref_switch(tgt); /* Pending qios */ qcow2_flush_deferred_activity(tgt, qcow2); /* Delayed md pages */ @@ -396,7 +418,7 @@ void qcow2_merge_backward_cancel(struct qcow2_target *tgt) } else if (tgt->backward_merge.state == BACKWARD_MERGE_STOP) { flush = true; } else if (tgt->backward_merge.state == BACKWARD_MERGE_WAIT_COMPLETION) { - set_backward_merge_in_process(tgt, tgt->top, false); + set_backward_merge_in_process(tgt, *tgt->backward_merge.pqcow2, false); tgt->backward_merge.state = BACKWARD_MERGE_STOPPED; __backward_merge_update_stage(tgt, BACKWARD_MERGE_STAGE_NONE); } @@ -571,7 +593,7 @@ int qcow2_message(struct dm_target *ti, unsigned int argc, char **argv, { struct qcow2_target *tgt = to_qcow2_target(ti); int ret = -EPERM; - u32 val, val2; + u32 val, val2, depth = 0; int efd; if (!capable(CAP_SYS_ADMIN)) @@ -652,11 +674,15 @@ int qcow2_message(struct dm_target *ti, unsigned int argc, char **argv, } else if (!strcmp(argv[0], "merge_backward")) { /* argc >= 2 */ if (!strcmp(argv[1], "start")) { - if (argc != 3 || kstrtoint(argv[2], 10, &efd) || efd < 0) { + if (argc < 3 || argc > 4 || kstrtoint(argv[2], 10, &efd) || efd < 0) { ret = -EINVAL; goto out_unlock; } - ret = qcow2_merge_backward_start(tgt, efd); + if (argc == 4 && kstrtou32(argv[3], 10, &depth)) { + ret = -EINVAL; + goto out_unlock; + } + ret = qcow2_merge_backward_start(tgt, efd, depth); } else if (!strcmp(argv[1], "complete")) { if (argc != 2) { ret = -EINVAL; diff --git a/drivers/md/dm-qcow2.h b/drivers/md/dm-qcow2.h index 5aa00c6a5ebd5..c50b578fb8b50 100644 --- a/drivers/md/dm-qcow2.h +++ b/drivers/md/dm-qcow2.h @@ -172,6 +172,7 @@ enum qcow2_backward_merge_stage { struct qcow2_backward_merge { struct work_struct work; + struct qcow2 **pqcow2; enum qcow2_backward_merge_state state; int error; struct eventfd_ctx *eventfd_ctx; -- 2.43.5 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
