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[130.117.225.111]) by mx.google.com with ESMTPS id ffacd0b85a97d-482fbb52b13si3716852f8f.450.2026.08.28.10.03.52 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Aug 2026 10:03:52 -0700 (PDT) Received-SPF: pass (google.com: domain of khorenko@virtuozzo.com designates 130.117.225.111 as permitted sender) client-ip=130.117.225.111; Authentication-Results: mx.google.com; dkim=pass header.i=@virtuozzo.com header.s=relay header.b=mrPKNuGE; spf=pass (google.com: domain of khorenko@virtuozzo.com designates 130.117.225.111 as permitted sender) smtp.mailfrom=khorenko@virtuozzo.com; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=virtuozzo.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=Subject:From:Message-Id:Date:Content-Type: MIME-Version; bh=2UVtNWaZKstJJx3w8slcdkEQu7t71s3iFtmtVfQWksg=; b=mrPKNuGEzWgw aFYYIs7vQDkbEgot8yAmn5vdDFtini8jPF/DuJsG/fJ6jrWeiQhBH5fueRX6AqkRXa06FUNUdNkTu heeVHU3YD5o7v5ZyzLvMOPw9pN5O/zdqOqVt8krMT334eKZeYXLUKdV/y6yjBgTJtbRYjVZR6owwq /uxRgPgmhRogGbSsNXKvj8BzUF5BVN4FPne99yBGGUcpatGjrGK5d7CZK/FVTXRdVTBD/YgK8X59u N/4tL0o5sCFcVy/0jdaarWQWogy8/X0bFbcyKPwSYxqr56ee5ysA9ElPxgFLbJGDSd/MGpXT2oh6a /FIUO6KFqGuXkV83HC1hng==; Received: from ch-demo-asa.virtuozzo.com ([130.117.225.8] helo=f0.sw.ru) by relay.virtuozzo.com with esmtps (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1wzzxK-008dtx-0c; Fri, 28 Aug 2026 19:03:48 +0200 Received: from f0.sw.ru (localhost [127.0.0.1]) by f0.sw.ru (8.18.1/8.18.1/Debian-2) with ESMTP id 67SH3orL1064018; Fri, 28 Aug 2026 19:03:51 +0200 Received: (from kostja@localhost) by f0.sw.ru (8.18.1/8.18.1/Submit) id 67SH3oRD1064013; Fri, 28 Aug 2026 19:03:50 +0200 Date: Fri, 28 Aug 2026 19:03:50 +0200 Message-Id: <202608281703.67SH3oRD1064013@f0.sw.ru> X-Authentication-Warning: f0.sw.ru: kostja set sender to khorenko@virtuozzo.com using -f From: Konstantin Khorenko To: Andrey Zhadchenko In-Reply-to: <20260827160619.303398-9-andrey.zhadchenko@virtuozzo.com> X-OZ-Fwd: true Cc: OpenVZ devel Subject: Re: [Devel] [PATCH RHEL10 COMMIT] drivers/md/dm-qcow2: unmap cluster when discard clears last allocated subclusters X-BeenThere: devel@openvz.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: OpenVZ development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: devel-bounces@openvz.org Errors-To: devel-bounces@openvz.org The commit is pushed to "branch-rh10-6.12.0-211.39.1.16.x.vz10-ovz" and will appear at git@bitbucket.org:openvz/vzkernel.git after rh10-6.12.0-211.39.1.16.11.vz10 ------> commit 308a75e8320d7b50d8e445a288ed6d664ce5de10 Author: Andrey Zhadchenko Date: Thu Aug 27 19:06:16 2026 +0300 drivers/md/dm-qcow2: unmap cluster when discard clears last allocated subclusters A subclusters discard only clears bits in the extended L2 bitmap and keeps the cluster mapped. Teach dm-qcow2 to clear L2 entry if every subcluster is discarded. Feature: dm-qcow2: block device over QCOW2 files driver https://virtuozzo.atlassian.net/browse/VSTOR-139406 Signed-off-by: Andrey Zhadchenko Reviewed-by: Pavel Tikhomirov Reviewed-by: Vasileios Almpanis Reviewed-by: Konstantin Khorenko --- drivers/md/dm-qcow2-map.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/drivers/md/dm-qcow2-map.c b/drivers/md/dm-qcow2-map.c index badd74e338de1..3154cae955916 100644 --- a/drivers/md/dm-qcow2-map.c +++ b/drivers/md/dm-qcow2-map.c @@ -122,6 +122,17 @@ static u32 qio_full_subclus_mask(struct qcow2 *qcow2, struct qio *qio) return GENMASK(end_bit - 1, first_bit); } +static bool qio_discard_unmaps_cluster(struct qcow2 *qcow2, struct qio *qio, + struct qcow2_map *map) +{ + if (qio_covers_full_clu(qcow2, qio)) + return true; + if (!qcow2->ext_l2 || map->compressed) + return false; + return (u32)map->ext_l2 && + !((u32)map->ext_l2 & ~qio_full_subclus_mask(qcow2, qio)); +} + static loff_t compressed_clu_end_pos(loff_t start, sector_t compressed_sectors) { if (start % SECTOR_SIZE == 0) @@ -2044,9 +2055,10 @@ static int parse_metadata(struct qcow2 *qcow2, struct qio **qio, if (!write) return 0; - /* discards also need to update r1r2 */ + /* cluster unmapping discards also need to update r1r2 */ if (!map->clu_is_cow && - !(op_is_discard((*qio)->bi_op) && qio_covers_full_clu(qcow2, *qio))) + !(op_is_discard((*qio)->bi_op) && + qio_discard_unmaps_cluster(qcow2, *qio, map))) return 0; /* Now refcounters table/block */ @@ -3399,6 +3411,8 @@ static bool qio_discard_updates_metadata(struct qcow2 *qcow2, struct qio *qio, * Subclusters fully covered by the discard are marked unallocated in * ext_l2 bitmap: the cluster itself remains allocated, so refcounts * are not touched (hence empty unuse range). + * Discarding last subclusters in a cluster clears it from L2 like a + * whole cluster discard. * If the backing is present, set 'reads as zeroes' to avoid exposing * stale data. */ @@ -3409,7 +3423,7 @@ static int prepare_cluster_discard(struct qcow2 *qcow2, struct qio **qio, u32 index_in_page = map->l2.index_in_page; struct md_page *md = map->l2.md; loff_t unuse_pos, unuse_end; - bool whole_clu; + bool whole_clu, unmap; struct qio_ext *ext; u64 new_ext_l2 = 0; int ret; @@ -3427,6 +3441,8 @@ static int prepare_cluster_discard(struct qcow2 *qcow2, struct qio **qio, spin_unlock_irq(&qcow2->md_pages_lock); whole_clu = qio_covers_full_clu(qcow2, *qio); + unmap = qio_discard_unmaps_cluster(qcow2, *qio, map); + if (whole_clu) { if (zeroes && qcow2->ext_l2) new_ext_l2 = (u64)U32_MAX << 32; @@ -3438,7 +3454,7 @@ static int prepare_cluster_discard(struct qcow2 *qcow2, struct qio **qio, new_ext_l2 |= mask << 32; } - if (whole_clu) { + if (unmap) { if (map->clu_is_cow) { /* Cluster is shared or compressed. Decrement refcount. */ unuse_pos = map->cow_clu_pos; @@ -3463,7 +3479,7 @@ static int prepare_cluster_discard(struct qcow2 *qcow2, struct qio **qio, ext->lx_md = md; ext->new_ext_l2 = new_ext_l2; - if (!whole_clu) + if (!unmap) ext->only_set_ext_l2 = true; else if (zeroes && !qcow2->ext_l2) ext->set_all_zeroes = true; _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel