From patchwork Fri Sep 13 16:39:39 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Drobyshev X-Patchwork-Id: 13803834 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id E84B8FC6166 for ; Fri, 13 Sep 2024 16:41:06 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sp9Ks-0006Fq-Au; Fri, 13 Sep 2024 12:39:54 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sp9Kp-000655-Q0; Fri, 13 Sep 2024 12:39:51 -0400 Received: from relay.virtuozzo.com ([130.117.225.111]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sp9Km-0000qB-AW; Fri, 13 Sep 2024 12:39:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=MIME-Version:Message-Id:Date:Subject:From: Content-Type; bh=6TUH3hWc7yBnsdPjbzKjuhLzm0vMR7kWS8RnMuC3e3s=; b=IkA1j8vllWQK aNtIofazJvAr8V7nP2TEadx9CT/HSb+/xR2RZcgoLw6umCydkJueBCUh+h2JGZvfVRVc/x6YVSmoT SFQJkHQrZ8aIcLVu8YMMoP27Lp+T8+TdhxZmDvMdbvkp3JUGcT3kQPz4+0m9oki02cvoBRH6LySMO eFgiHxWzJjNwbAZCKIGVbNxTbL8cmcLqVZFWUPB3ABc2MvnTUxKXmam7a5RF46n2+9sJExMRXA11d 5WXUGME8CoCz9LAVVNglFumvwkXnWXbv7MswpDGKnbiD4BU8B72eyDYjDQcsKDnIXLZahFXZNEHv5 XkbUjxIiq/58FEA6GF7VHA==; Received: from [130.117.225.1] (helo=dev005.ch-qa.vzint.dev) by relay.virtuozzo.com with esmtp (Exim 4.96) (envelope-from ) id 1sp9Hz-002OPf-09; Fri, 13 Sep 2024 18:39:39 +0200 From: Andrey Drobyshev To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, hreitz@redhat.com, kwolf@redhat.com, eblake@redhat.com, stefanha@redhat.com, berto@igalia.com, andrey.drobyshev@virtuozzo.com, den@virtuozzo.com Subject: [PATCH v3 09/12] qcow2: make subclusters discardable Date: Fri, 13 Sep 2024 19:39:39 +0300 Message-Id: <20240913163942.423050-10-andrey.drobyshev@virtuozzo.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20240913163942.423050-1-andrey.drobyshev@virtuozzo.com> References: <20240913163942.423050-1-andrey.drobyshev@virtuozzo.com> MIME-Version: 1.0 Received-SPF: pass client-ip=130.117.225.111; envelope-from=andrey.drobyshev@virtuozzo.com; helo=relay.virtuozzo.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, 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: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org This commit makes the discard operation work on the subcluster level rather than cluster level. It introduces discard_l2_subclusters() function and makes use of it in qcow2 discard implementation, much like it's done with zero_in_l2_slice() / zero_l2_subclusters(). It also changes the qcow2 driver pdiscard_alignment to subcluster_size. That way subcluster-aligned discards lead to actual fallocate(PUNCH_HOLE) operation and free host disk space. This feature will let us gain additional disk space on guest TRIM/discard requests, especially when using large enough clusters (1M, 2M) with subclusters enabled. Also rename qcow2_cluster_discard() -> qcow2_subcluster_discard() to reflect the change. Signed-off-by: Andrey Drobyshev Reviewed-by: Alexander Ivanov --- block/qcow2-cluster.c | 106 +++++++++++++++++++++++++++++++++++++---- block/qcow2-snapshot.c | 6 +-- block/qcow2.c | 25 +++++----- block/qcow2.h | 4 +- tests/qemu-iotests/271 | 2 +- 5 files changed, 117 insertions(+), 26 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 8d39e2f960..3c134a7e80 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -2105,25 +2105,106 @@ discard_in_l2_slice(BlockDriverState *bs, uint64_t offset, uint64_t nb_clusters, return nb_clusters; } -int qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset, - uint64_t bytes, enum qcow2_discard_type type, - bool full_discard) +static int coroutine_fn GRAPH_RDLOCK +discard_l2_subclusters(BlockDriverState *bs, uint64_t offset, + uint64_t nb_subclusters, + enum qcow2_discard_type type, + bool full_discard) +{ + BDRVQcow2State *s = bs->opaque; + uint64_t new_l2_bitmap, bitmap_alloc_mask, bitmap_zero_mask; + int ret, sc = offset_to_sc_index(s, offset); + g_auto(SubClusterRangeInfo) scri = { 0 }; + + ret = get_sc_range_info(bs, offset, nb_subclusters, &scri); + if (ret < 0) { + return ret; + } + + new_l2_bitmap = scri.l2_bitmap; + bitmap_alloc_mask = QCOW_OFLAG_SUB_ALLOC_RANGE(sc, sc + nb_subclusters); + bitmap_zero_mask = QCOW_OFLAG_SUB_ZERO_RANGE(sc, sc + nb_subclusters); + + new_l2_bitmap &= ~bitmap_alloc_mask; + + /* + * Full discard means we fall through to the backing file, thus we need + * to mark the subclusters as deallocated and clear the corresponding + * zero bits. + * + * Non-full discard means subclusters should be explicitly marked as + * zeroes. In this case QCOW2 specification requires the corresponding + * allocation status bits to be unset as well. If the subclusters are + * deallocated in the first place and there's no backing, the operation + * can be skipped. + */ + if (full_discard) { + new_l2_bitmap &= ~bitmap_zero_mask; + } else if (bs->backing || scri.l2_bitmap & bitmap_alloc_mask) { + new_l2_bitmap |= bitmap_zero_mask; + } + + /* + * If after discarding this range there won't be any allocated subclusters + * left, and new bitmap becomes the same as it'd be after discarding the + * whole cluster, we better discard it entirely. That way we'd also + * update the refcount table. + */ + if ((full_discard && new_l2_bitmap == 0) || + (!full_discard && new_l2_bitmap == QCOW_L2_BITMAP_ALL_ZEROES)) { + return discard_in_l2_slice( + bs, QEMU_ALIGN_DOWN(offset, s->cluster_size), + 1, type, full_discard); + } + + if (scri.l2_bitmap != new_l2_bitmap) { + set_l2_bitmap(s, scri.l2_slice, scri.l2_index, new_l2_bitmap); + qcow2_cache_entry_mark_dirty(s->l2_table_cache, scri.l2_slice); + } + + discard_no_unref_any_file( + bs, (scri.l2_entry & L2E_OFFSET_MASK) + offset_into_cluster(s, offset), + nb_subclusters * s->subcluster_size, scri.ctype, type); + + return 0; +} + +int qcow2_subcluster_discard(BlockDriverState *bs, uint64_t offset, + uint64_t bytes, enum qcow2_discard_type type, + bool full_discard) { BDRVQcow2State *s = bs->opaque; uint64_t end_offset = offset + bytes; uint64_t nb_clusters; + unsigned head, tail; int64_t cleared; int ret; /* Caller must pass aligned values, except at image end */ - assert(QEMU_IS_ALIGNED(offset, s->cluster_size)); - assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size) || + assert(QEMU_IS_ALIGNED(offset, s->subcluster_size)); + assert(QEMU_IS_ALIGNED(end_offset, s->subcluster_size) || end_offset == bs->total_sectors << BDRV_SECTOR_BITS); - nb_clusters = size_to_clusters(s, bytes); + head = MIN(end_offset, ROUND_UP(offset, s->cluster_size)) - offset; + offset += head; + + tail = (end_offset >= bs->total_sectors << BDRV_SECTOR_BITS) ? 0 : + end_offset - MAX(offset, start_of_cluster(s, end_offset)); + end_offset -= tail; s->cache_discards = true; + if (head) { + ret = discard_l2_subclusters(bs, offset - head, + size_to_subclusters(s, head), type, + full_discard); + if (ret < 0) { + goto fail; + } + } + + nb_clusters = size_to_clusters(s, end_offset - offset); + /* Each L2 slice is handled by its own loop iteration */ while (nb_clusters > 0) { cleared = discard_in_l2_slice(bs, offset, nb_clusters, type, @@ -2137,6 +2218,15 @@ int qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset, offset += (cleared * s->cluster_size); } + if (tail) { + ret = discard_l2_subclusters(bs, end_offset, + size_to_subclusters(s, tail), type, + full_discard); + if (ret < 0) { + goto fail; + } + } + ret = 0; fail: s->cache_discards = false; @@ -2286,8 +2376,8 @@ int coroutine_fn qcow2_subcluster_zeroize(BlockDriverState *bs, uint64_t offset, */ if (s->qcow_version < 3) { if (!bs->backing) { - return qcow2_cluster_discard(bs, offset, bytes, - QCOW2_DISCARD_REQUEST, false); + return qcow2_subcluster_discard(bs, offset, bytes, + QCOW2_DISCARD_REQUEST, false); } return -ENOTSUP; } diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index 92e47978bf..4e39354d02 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -736,9 +736,9 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info) /* The VM state isn't needed any more in the active L1 table; in fact, it * hurts by causing expensive COW for the next snapshot. */ - qcow2_cluster_discard(bs, qcow2_vm_state_offset(s), - ROUND_UP(sn->vm_state_size, s->cluster_size), - QCOW2_DISCARD_NEVER, false); + qcow2_subcluster_discard(bs, qcow2_vm_state_offset(s), + ROUND_UP(sn->vm_state_size, s->cluster_size), + QCOW2_DISCARD_NEVER, false); #ifdef DEBUG_ALLOC { diff --git a/block/qcow2.c b/block/qcow2.c index dd359d241b..c2086d0bd1 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1981,7 +1981,7 @@ static void qcow2_refresh_limits(BlockDriverState *bs, Error **errp) bs->bl.request_alignment = qcrypto_block_get_sector_size(s->crypto); } bs->bl.pwrite_zeroes_alignment = s->subcluster_size; - bs->bl.pdiscard_alignment = s->cluster_size; + bs->bl.pdiscard_alignment = s->subcluster_size; } static int GRAPH_UNLOCKED @@ -4126,19 +4126,19 @@ qcow2_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes) return -ENOTSUP; } - if (!QEMU_IS_ALIGNED(offset | bytes, s->cluster_size)) { - assert(bytes < s->cluster_size); + if (!QEMU_IS_ALIGNED(offset | bytes, bs->bl.pdiscard_alignment)) { + assert(bytes < bs->bl.pdiscard_alignment); /* Ignore partial clusters, except for the special case of the * complete partial cluster at the end of an unaligned file */ - if (!QEMU_IS_ALIGNED(offset, s->cluster_size) || + if (!QEMU_IS_ALIGNED(offset, bs->bl.pdiscard_alignment) || offset + bytes != bs->total_sectors * BDRV_SECTOR_SIZE) { return -ENOTSUP; } } qemu_co_mutex_lock(&s->lock); - ret = qcow2_cluster_discard(bs, offset, bytes, QCOW2_DISCARD_REQUEST, - false); + ret = qcow2_subcluster_discard(bs, offset, bytes, QCOW2_DISCARD_REQUEST, + false); qemu_co_mutex_unlock(&s->lock); return ret; } @@ -4349,10 +4349,10 @@ qcow2_co_truncate(BlockDriverState *bs, int64_t offset, bool exact, goto fail; } - ret = qcow2_cluster_discard(bs, ROUND_UP(offset, s->cluster_size), - old_length - ROUND_UP(offset, - s->cluster_size), - QCOW2_DISCARD_ALWAYS, true); + ret = qcow2_subcluster_discard(bs, ROUND_UP(offset, s->cluster_size), + old_length - ROUND_UP(offset, + s->cluster_size), + QCOW2_DISCARD_ALWAYS, true); if (ret < 0) { error_setg_errno(errp, -ret, "Failed to discard cropped clusters"); goto fail; @@ -5046,8 +5046,9 @@ static int GRAPH_RDLOCK qcow2_make_empty(BlockDriverState *bs) * default action for this kind of discard is to pass the discard, * which will ideally result in an actually smaller image file, as * is probably desired. */ - ret = qcow2_cluster_discard(bs, offset, MIN(step, end_offset - offset), - QCOW2_DISCARD_SNAPSHOT, true); + ret = qcow2_subcluster_discard(bs, offset, + MIN(step, end_offset - offset), + QCOW2_DISCARD_SNAPSHOT, true); if (ret < 0) { break; } diff --git a/block/qcow2.h b/block/qcow2.h index 197bdcdf53..a65c185b51 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -953,8 +953,8 @@ void coroutine_fn GRAPH_RDLOCK qcow2_alloc_cluster_abort(BlockDriverState *bs, QCowL2Meta *m); int GRAPH_RDLOCK -qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset, uint64_t bytes, - enum qcow2_discard_type type, bool full_discard); +qcow2_subcluster_discard(BlockDriverState *bs, uint64_t offset, uint64_t bytes, + enum qcow2_discard_type type, bool full_discard); int coroutine_fn GRAPH_RDLOCK qcow2_subcluster_zeroize(BlockDriverState *bs, uint64_t offset, uint64_t bytes, diff --git a/tests/qemu-iotests/271 b/tests/qemu-iotests/271 index 59a6fafa2f..04c57813c2 100755 --- a/tests/qemu-iotests/271 +++ b/tests/qemu-iotests/271 @@ -518,7 +518,7 @@ done ############################################################ ############################################################ -# Test qcow2_cluster_discard() with full and normal discards +# Test qcow2_subcluster_discard() with full and normal discards for use_backing_file in yes no; do echo echo "### Discarding clusters with non-zero bitmaps (backing file: $use_backing_file) ###"