From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:46703) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ULFtN-0006O9-Kc for qemu-devel@nongnu.org; Thu, 28 Mar 2013 12:41:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ULFtK-0002JU-0E for qemu-devel@nongnu.org; Thu, 28 Mar 2013 12:41:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38985) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ULFtJ-0002JL-Ov for qemu-devel@nongnu.org; Thu, 28 Mar 2013 12:41:29 -0400 From: Stefan Hajnoczi Date: Thu, 28 Mar 2013 17:40:35 +0100 Message-Id: <1364488837-15916-22-git-send-email-stefanha@redhat.com> In-Reply-To: <1364488837-15916-1-git-send-email-stefanha@redhat.com> References: <1364488837-15916-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PATCH 21/23] qcow2: Move cluster gathering to a non-looping loop List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Anthony Liguori , Stefan Hajnoczi From: Kevin Wolf This patch is mainly to separate the indentation change from the semantic changes. All that really changes here is that everything moves into a while loop, all 'goto done' become 'break' and at the end of the loop a new 'break is inserted. Signed-off-by: Kevin Wolf Signed-off-by: Stefan Hajnoczi --- block/qcow2-cluster.c | 134 ++++++++++++++++++++++++++------------------------ 1 file changed, 70 insertions(+), 64 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 6dc7f7f..960d446 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1147,79 +1147,85 @@ again: cluster_offset = 0; *host_offset = 0; - /* - * Now start gathering as many contiguous clusters as possible: - * - * 1. Check for overlaps with in-flight allocations - * - * a) Overlap not in the first cluster -> shorten this request and let - * the caller handle the rest in its next loop iteration. - * - * b) Real overlaps of two requests. Yield and restart the search for - * contiguous clusters (the situation could have changed while we - * were sleeping) - * - * c) TODO: Request starts in the same cluster as the in-flight - * allocation ends. Shorten the COW of the in-fight allocation, set - * cluster_offset to write to the same cluster and set up the right - * synchronisation between the in-flight request and the new one. - */ - cur_bytes = remaining; - ret = handle_dependencies(bs, start, &cur_bytes); - if (ret == -EAGAIN) { - goto again; - } else if (ret < 0) { - return ret; - } else { - /* handle_dependencies() may have decreased cur_bytes (shortened - * the allocations below) so that the next dependency is processed - * correctly during the next loop iteration. */ - } - - /* - * 2. Count contiguous COPIED clusters. - */ - ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m); - if (ret < 0) { - return ret; - } else if (ret) { - if (!*host_offset) { - *host_offset = start_of_cluster(s, cluster_offset); + while (true) { + /* + * Now start gathering as many contiguous clusters as possible: + * + * 1. Check for overlaps with in-flight allocations + * + * a) Overlap not in the first cluster -> shorten this request and + * let the caller handle the rest in its next loop iteration. + * + * b) Real overlaps of two requests. Yield and restart the search + * for contiguous clusters (the situation could have changed + * while we were sleeping) + * + * c) TODO: Request starts in the same cluster as the in-flight + * allocation ends. Shorten the COW of the in-fight allocation, + * set cluster_offset to write to the same cluster and set up + * the right synchronisation between the in-flight request and + * the new one. + */ + cur_bytes = remaining; + ret = handle_dependencies(bs, start, &cur_bytes); + if (ret == -EAGAIN) { + goto again; + } else if (ret < 0) { + return ret; + } else { + /* handle_dependencies() may have decreased cur_bytes (shortened + * the allocations below) so that the next dependency is processed + * correctly during the next loop iteration. */ } - start += cur_bytes; - remaining -= cur_bytes; - cluster_offset += cur_bytes; + /* + * 2. Count contiguous COPIED clusters. + */ + ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m); + if (ret < 0) { + return ret; + } else if (ret) { + if (!*host_offset) { + *host_offset = start_of_cluster(s, cluster_offset); + } - cur_bytes = remaining; - } else if (cur_bytes == 0) { - goto done; - } + start += cur_bytes; + remaining -= cur_bytes; + cluster_offset += cur_bytes; - /* If there is something left to allocate, do that now */ - if (remaining == 0) { - goto done; - } + cur_bytes = remaining; + } else if (cur_bytes == 0) { + break; + } - /* - * 3. If the request still hasn't completed, allocate new clusters, - * considering any cluster_offset of steps 1c or 2. - */ - ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m); - if (ret < 0) { - return ret; - } else if (ret) { - if (!*host_offset) { - *host_offset = start_of_cluster(s, cluster_offset); + /* If there is something left to allocate, do that now */ + if (remaining == 0) { + break; } - start += cur_bytes; - remaining -= cur_bytes; - cluster_offset += cur_bytes; + /* + * 3. If the request still hasn't completed, allocate new clusters, + * considering any cluster_offset of steps 1c or 2. + */ + ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m); + if (ret < 0) { + return ret; + } else if (ret) { + if (!*host_offset) { + *host_offset = start_of_cluster(s, cluster_offset); + } + + start += cur_bytes; + remaining -= cur_bytes; + cluster_offset += cur_bytes; + + break; + } else { + assert(cur_bytes == 0); + break; + } } - /* Some cleanup work */ -done: *num = (n_end - n_start) - (remaining >> BDRV_SECTOR_BITS); assert(*num > 0); assert(*host_offset != 0); -- 1.8.1.4