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Mon, 7 Sep 2020 11:10:22 +0000 (UTC) Received: from linux.fritz.box.com (ovpn-114-154.ams2.redhat.com [10.36.114.154]) by smtp.corp.redhat.com (Postfix) with ESMTP id D34DC9CBA; Mon, 7 Sep 2020 11:10:21 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PULL 29/64] block: Use CAFs when working with backing chains Date: Mon, 7 Sep 2020 13:09:01 +0200 Message-Id: <20200907110936.261684-30-kwolf@redhat.com> In-Reply-To: <20200907110936.261684-1-kwolf@redhat.com> References: <20200907110936.261684-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=205.139.110.61; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/07 03:05:01 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no 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, peter.maydell@linaro.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Max Reitz Use child access functions when iterating through backing chains so filters do not break the chain. In addition, bdrv_find_overlay() will now always return the actual overlay; that is, it will never return a filter node but only one with a COW backing file (there may be filter nodes between that node and @bs). Signed-off-by: Max Reitz --- block.c | 44 ++++++++++++++++++++++++++++++-------------- 1 file changed, 30 insertions(+), 14 deletions(-) diff --git a/block.c b/block.c index 887c125400..96bf8672f1 100644 --- a/block.c +++ b/block.c @@ -4745,9 +4745,9 @@ int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file, } /* - * Finds the image layer in the chain that has 'bs' as its backing file. - * - * active is the current topmost image. + * Finds the first non-filter node above bs in the chain between + * active and bs. The returned node is either an immediate parent of + * bs, or there are only filter nodes between the two. * * Returns NULL if bs is not found in active's image chain, * or if active == bs. @@ -4757,11 +4757,18 @@ int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file, BlockDriverState *bdrv_find_overlay(BlockDriverState *active, BlockDriverState *bs) { - while (active && bs != backing_bs(active)) { - active = backing_bs(active); + bs = bdrv_skip_filters(bs); + active = bdrv_skip_filters(active); + + while (active) { + BlockDriverState *next = bdrv_backing_chain_next(active); + if (bs == next) { + return active; + } + active = next; } - return active; + return NULL; } /* Given a BDS, searches for the base layer. */ @@ -4913,9 +4920,7 @@ int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base, * other intermediate nodes have been dropped. * If 'top' is an implicit node (e.g. "commit_top") we should skip * it because no one inherits from it. We use explicit_top for that. */ - while (explicit_top && explicit_top->implicit) { - explicit_top = backing_bs(explicit_top); - } + explicit_top = bdrv_skip_implicit_filters(explicit_top); update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top); /* success - we can delete the intermediate states, and link top->base */ @@ -5372,7 +5377,7 @@ BlockDriverState *bdrv_lookup_bs(const char *device, bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base) { while (top && top != base) { - top = backing_bs(top); + top = bdrv_filter_or_cow_bs(top); } return top != NULL; @@ -5613,6 +5618,7 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, int is_protocol = 0; BlockDriverState *curr_bs = NULL; BlockDriverState *retval = NULL; + BlockDriverState *bs_below; if (!bs || !bs->drv || !backing_file) { return NULL; @@ -5623,7 +5629,17 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, is_protocol = path_has_protocol(backing_file); - for (curr_bs = bs; curr_bs->backing; curr_bs = curr_bs->backing->bs) { + /* + * Being largely a legacy function, skip any filters here + * (because filters do not have normal filenames, so they cannot + * match anyway; and allowing json:{} filenames is a bit out of + * scope). + */ + for (curr_bs = bdrv_skip_filters(bs); + bdrv_cow_child(curr_bs) != NULL; + curr_bs = bs_below) + { + bs_below = bdrv_backing_chain_next(curr_bs); /* If either of the filename paths is actually a protocol, then * compare unmodified paths; otherwise make paths relative */ @@ -5631,7 +5647,7 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, char *backing_file_full_ret; if (strcmp(backing_file, curr_bs->backing_file) == 0) { - retval = curr_bs->backing->bs; + retval = bs_below; break; } /* Also check against the full backing filename for the image */ @@ -5641,7 +5657,7 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, bool equal = strcmp(backing_file, backing_file_full_ret) == 0; g_free(backing_file_full_ret); if (equal) { - retval = curr_bs->backing->bs; + retval = bs_below; break; } } @@ -5667,7 +5683,7 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, g_free(filename_tmp); if (strcmp(backing_file_full, filename_full) == 0) { - retval = curr_bs->backing->bs; + retval = bs_below; break; } }