From patchwork Tue May 12 16:50:37 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Shinkevich X-Patchwork-Id: 11543619 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 53A31139F for ; Tue, 12 May 2020 17:02:32 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 33539206B8 for ; Tue, 12 May 2020 17:02:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 33539206B8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=virtuozzo.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:52764 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jYYIZ-0007BI-CY for patchwork-qemu-devel@patchwork.kernel.org; Tue, 12 May 2020 13:02:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52414) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jYY7U-0004r6-Cy; Tue, 12 May 2020 12:51:04 -0400 Received: from relay.sw.ru ([185.231.240.75]:50530) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jYY7P-0001R4-3b; Tue, 12 May 2020 12:51:04 -0400 Received: from dhcp-172-16-25-136.sw.ru ([172.16.25.136] helo=localhost.sw.ru) by relay.sw.ru with esmtp (Exim 4.92.3) (envelope-from ) id 1jYY7C-0004nT-Vv; Tue, 12 May 2020 19:50:47 +0300 From: Andrey Shinkevich To: qemu-block@nongnu.org Subject: [PATCH v4 07/15] commit: Deal with filters when blocking intermediate nodes Date: Tue, 12 May 2020 19:50:37 +0300 Message-Id: <1589302245-893269-8-git-send-email-andrey.shinkevich@virtuozzo.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1589302245-893269-1-git-send-email-andrey.shinkevich@virtuozzo.com> References: <1589302245-893269-1-git-send-email-andrey.shinkevich@virtuozzo.com> Received-SPF: pass client-ip=185.231.240.75; envelope-from=andrey.shinkevich@virtuozzo.com; helo=relay.sw.ru X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/12 10:53:25 X-ACL-Warn: Detected OS = Linux 3.1-3.10 X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, fam@euphon.net, vsementsov@virtuozzo.com, armbru@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com, andrey.shinkevich@virtuozzo.com, den@openvz.org, mreitz@redhat.com, jsnow@redhat.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: Max Reitz This includes some permission limiting (for example, we only need to take the RESIZE permission if the base is smaller than the top). Signed-off-by: Max Reitz Signed-off-by: Andrey Shinkevich --- block/commit.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 60 insertions(+), 15 deletions(-) diff --git a/block/commit.c b/block/commit.c index e1f45a4..4df145d 100644 --- a/block/commit.c +++ b/block/commit.c @@ -37,6 +37,7 @@ typedef struct CommitBlockJob { BlockBackend *top; BlockBackend *base; BlockDriverState *base_bs; + BlockDriverState *above_base; BlockdevOnError on_error; bool base_read_only; bool chain_frozen; @@ -153,7 +154,7 @@ static int coroutine_fn commit_run(Job *job, Error **errp) break; } /* Copy if allocated above the base */ - ret = bdrv_is_allocated_above(blk_bs(s->top), blk_bs(s->base), false, + ret = bdrv_is_allocated_above(blk_bs(s->top), s->above_base, true, offset, COMMIT_BUFFER_SIZE, &n); copy = (ret == 1); trace_commit_one_iteration(s, offset, n, ret); @@ -253,15 +254,35 @@ void commit_start(const char *job_id, BlockDriverState *bs, CommitBlockJob *s; BlockDriverState *iter; BlockDriverState *commit_top_bs = NULL; + BlockDriverState *filtered_base; Error *local_err = NULL; + int64_t base_size, top_size; + uint64_t perms, iter_shared_perms; int ret; assert(top != bs); - if (top == base) { + if (bdrv_skip_rw_filters(top) == bdrv_skip_rw_filters(base)) { error_setg(errp, "Invalid files for merge: top and base are the same"); return; } + base_size = bdrv_getlength(base); + if (base_size < 0) { + error_setg_errno(errp, -base_size, "Could not inquire base image size"); + return; + } + + top_size = bdrv_getlength(top); + if (top_size < 0) { + error_setg_errno(errp, -top_size, "Could not inquire top image size"); + return; + } + + perms = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; + if (base_size < top_size) { + perms |= BLK_PERM_RESIZE; + } + s = block_job_create(job_id, &commit_job_driver, NULL, bs, 0, BLK_PERM_ALL, speed, creation_flags, NULL, NULL, errp); if (!s) { @@ -301,17 +322,43 @@ void commit_start(const char *job_id, BlockDriverState *bs, s->commit_top_bs = commit_top_bs; - /* Block all nodes between top and base, because they will - * disappear from the chain after this operation. */ - assert(bdrv_chain_contains(top, base)); - for (iter = top; iter != base; iter = backing_bs(iter)) { - /* XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves - * at s->base (if writes are blocked for a node, they are also blocked - * for its backing file). The other options would be a second filter - * driver above s->base. */ + /* + * Block all nodes between top and base, because they will + * disappear from the chain after this operation. + * Note that this assumes that the user is fine with removing all + * nodes (including R/W filters) between top and base. Assuring + * this is the responsibility of the interface (i.e. whoever calls + * commit_start()). + */ + s->above_base = bdrv_find_overlay(top, base); + assert(s->above_base); + + /* + * The topmost node with + * bdrv_skip_rw_filters(filtered_base) == bdrv_skip_rw_filters(base) + */ + filtered_base = bdrv_filtered_cow_bs(s->above_base); + assert(bdrv_skip_rw_filters(filtered_base) == bdrv_skip_rw_filters(base)); + + /* + * XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves + * at s->base (if writes are blocked for a node, they are also blocked + * for its backing file). The other options would be a second filter + * driver above s->base. + */ + iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE; + + for (iter = top; iter != base; iter = bdrv_filtered_bs(iter)) { + if (iter == filtered_base) { + /* + * From here on, all nodes are filters on the base. This + * allows us to share BLK_PERM_CONSISTENT_READ. + */ + iter_shared_perms |= BLK_PERM_CONSISTENT_READ; + } + ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, - BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE, - errp); + iter_shared_perms, errp); if (ret < 0) { goto fail; } @@ -328,9 +375,7 @@ void commit_start(const char *job_id, BlockDriverState *bs, } s->base = blk_new(s->common.job.aio_context, - BLK_PERM_CONSISTENT_READ - | BLK_PERM_WRITE - | BLK_PERM_RESIZE, + perms, BLK_PERM_CONSISTENT_READ | BLK_PERM_GRAPH_MOD | BLK_PERM_WRITE_UNCHANGED);