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Lunev" , Michael Tokarev Subject: [Stable-10.2.3 145/149] commit: Drain nodes across all of bdrv_commit() Date: Sat, 23 May 2026 00:49:17 +0300 Message-ID: <20260522214923.807017-46-mjt@tls.msk.ru> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=212.248.84.144; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @tls.msk.ru) X-ZM-MESSAGEID: 1779486875760154100 Content-Type: text/plain; charset="utf-8" From: Kevin Wolf The whole implementation of bdrv_commit() is only correct if no new writes come in while it's running: It has only a single loop checking the allocation status for each block and finally calls bdrv_make_empty() without checking if that throws away any new changes. We already have to drain while taking the graph write lock. Just extend the drained section to all of bdrv_commit() to make sure that we don't get any inconsistencies. Signed-off-by: Kevin Wolf Message-ID: <20260427170520.101242-2-kwolf@redhat.com> Reviewed-by: Denis V. Lunev Tested-by: Denis V. Lunev Signed-off-by: Kevin Wolf (cherry picked from commit f0d9ccd46cf8fc576ab7d514f10f766546cdbc14) Signed-off-by: Michael Tokarev diff --git a/block/commit.c b/block/commit.c index 0d9e1a16d7..c5e3ef03a2 100644 --- a/block/commit.c +++ b/block/commit.c @@ -518,6 +518,7 @@ int bdrv_commit(BlockDriverState *bs) if (!drv) return -ENOMEDIUM; =20 + bdrv_drain_all_begin(); bdrv_graph_rdlock_main_loop(); =20 backing_file_bs =3D bdrv_cow_bs(bs); @@ -549,6 +550,10 @@ int bdrv_commit(BlockDriverState *bs) BLK_PERM_ALL); backing =3D blk_new(ctx, BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_AL= L); =20 + /* We drained all nodes, but still make requests through BlockBackends= */ + blk_set_disable_request_queuing(src, true); + blk_set_disable_request_queuing(backing, true); + ret =3D blk_insert_bs(src, bs, &local_err); if (ret < 0) { error_report_err(local_err); @@ -565,7 +570,7 @@ int bdrv_commit(BlockDriverState *bs) =20 bdrv_graph_rdunlock_main_loop(); =20 - bdrv_graph_wrlock_drained(); + bdrv_graph_wrlock(); bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort); bdrv_set_backing_hd(bs, commit_top_bs, &error_abort); bdrv_graph_wrunlock(); @@ -647,7 +652,7 @@ ro_cleanup: blk_unref(backing); =20 bdrv_graph_rdunlock_main_loop(); - bdrv_graph_wrlock_drained(); + bdrv_graph_wrlock(); if (bdrv_cow_bs(bs) !=3D backing_file_bs) { bdrv_set_backing_hd(bs, backing_file_bs, &error_abort); } @@ -663,6 +668,7 @@ ro_cleanup: =20 out: bdrv_graph_rdunlock_main_loop(); + bdrv_drain_all_end(); =20 return ret; } --=20 2.47.3