From patchwork Wed Dec 22 10:47:30 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miao Xie X-Patchwork-Id: 426611 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id oBMAjsPi004456 for ; Wed, 22 Dec 2010 10:45:55 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752028Ab0LVKpe (ORCPT ); Wed, 22 Dec 2010 05:45:34 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:64094 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751996Ab0LVKpd (ORCPT ); Wed, 22 Dec 2010 05:45:33 -0500 Received: from tang.cn.fujitsu.com (tang.cn.fujitsu.com [10.167.250.3]) by song.cn.fujitsu.com (Postfix) with ESMTP id B752B170A33; Wed, 22 Dec 2010 18:45:31 +0800 (CST) Received: from mailserver.fnst.cn.fujitus.com (tang.cn.fujitsu.com [127.0.0.1]) by tang.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id oBMAeb4w006247; Wed, 22 Dec 2010 18:40:38 +0800 Received: from [10.167.225.64] ([10.167.225.64]) by mailserver.fnst.cn.fujitus.com (Lotus Domino Release 8.5.1FP4) with ESMTP id 2010122218452470-28693 ; Wed, 22 Dec 2010 18:45:24 +0800 Message-ID: <4D11D742.9090504@cn.fujitsu.com> Date: Wed, 22 Dec 2010 18:47:30 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100413 Fedora/3.0.4-2.fc13 Thunderbird/3.0.4 MIME-Version: 1.0 To: Chris Mason , Josef Bacik CC: Linux Btrfs Subject: [PATCH 4/6] btrfs: restructure find_free_dev_extent() X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2010-12-22 18:45:24, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2010-12-22 18:45:24, Serialize complete at 2010-12-22 18:45:24 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter1.kernel.org [140.211.167.41]); Wed, 22 Dec 2010 10:45:55 +0000 (UTC) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 4bcd875..7c1a053 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -8098,7 +8098,7 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr) mutex_lock(&root->fs_info->chunk_mutex); list_for_each_entry(device, &fs_devices->alloc_list, dev_alloc_list) { u64 min_free = btrfs_block_group_used(&block_group->item); - u64 dev_offset, max_avail; + u64 dev_offset; /* * check to make sure we can actually find a chunk with enough @@ -8106,7 +8106,7 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr) */ if (device->total_bytes > device->bytes_used + min_free) { ret = find_free_dev_extent(NULL, device, min_free, - &dev_offset, &max_avail); + &dev_offset, NULL); if (!ret) break; ret = -1; diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index e1028f4..15e8c3f 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -729,58 +729,82 @@ error: } /* + * find_free_dev_extent - find free space in the specified device + * @trans: transaction handler + * @device: the device which we search the free space in + * @num_bytes: the size of the free space that we need + * @start: store the start of the free space. + * @len: the size of the free space. that we find, or the size of the max + * free space if we don't find suitable free space + * * this uses a pretty simple search, the expectation is that it is * called very infrequently and that a given device has a small number * of extents + * + * @start is used to store the start of the free space if we find. But if we + * don't find suitable free space, it will be used to store the start position + * of the max free space. + * + * @len is used to store the size of the free space that we find. + * But if we don't find suitable free space, it is used to store the size of + * the max free space. */ int find_free_dev_extent(struct btrfs_trans_handle *trans, struct btrfs_device *device, u64 num_bytes, - u64 *start, u64 *max_avail) + u64 *start, u64 *len) { struct btrfs_key key; struct btrfs_root *root = device->dev_root; - struct btrfs_dev_extent *dev_extent = NULL; + struct btrfs_dev_extent *dev_extent; struct btrfs_path *path; - u64 hole_size = 0; - u64 last_byte = 0; - u64 search_start = 0; + u64 hole_size; + u64 max_hole_start; + u64 max_hole_size; + u64 extent_end; + u64 search_start; u64 search_end = device->total_bytes; int ret; - int slot = 0; - int start_found; + int slot; struct extent_buffer *l; - path = btrfs_alloc_path(); - if (!path) - return -ENOMEM; - path->reada = 2; - start_found = 0; - /* FIXME use last free of some kind */ /* we don't want to overwrite the superblock on the drive, * so we make sure to start at an offset of at least 1MB */ - search_start = max((u64)1024 * 1024, search_start); + search_start = 1024 * 1024; - if (root->fs_info->alloc_start + num_bytes <= device->total_bytes) + if (root->fs_info->alloc_start + num_bytes <= search_end) search_start = max(root->fs_info->alloc_start, search_start); + max_hole_start = search_start; + max_hole_size = 0; + + if (search_start >= search_end) { + ret = -ENOSPC; + goto error; + } + + path = btrfs_alloc_path(); + if (!path) { + ret = -ENOMEM; + goto error; + } + path->reada = 2; + key.objectid = device->devid; key.offset = search_start; key.type = BTRFS_DEV_EXTENT_KEY; + ret = btrfs_search_slot(trans, root, &key, path, 0, 0); if (ret < 0) - goto error; + goto out; if (ret > 0) { ret = btrfs_previous_item(root, path, key.objectid, key.type); if (ret < 0) - goto error; - if (ret > 0) - start_found = 1; + goto out; } - l = path->nodes[0]; - btrfs_item_key_to_cpu(l, &key, path->slots[0]); + while (1) { l = path->nodes[0]; slot = path->slots[0]; @@ -789,24 +813,9 @@ int find_free_dev_extent(struct btrfs_trans_handle *trans, if (ret == 0) continue; if (ret < 0) - goto error; -no_more_items: - if (!start_found) { - if (search_start >= search_end) { - ret = -ENOSPC; - goto error; - } - *start = search_start; - start_found = 1; - goto check_pending; - } - *start = last_byte > search_start ? - last_byte : search_start; - if (search_end <= *start) { - ret = -ENOSPC; - goto error; - } - goto check_pending; + goto out; + + break; } btrfs_item_key_to_cpu(l, &key, slot); @@ -814,48 +823,62 @@ no_more_items: goto next; if (key.objectid > device->devid) - goto no_more_items; + break; - if (key.offset >= search_start && key.offset > last_byte && - start_found) { - if (last_byte < search_start) - last_byte = search_start; - hole_size = key.offset - last_byte; + if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY) + goto next; - if (hole_size > *max_avail) - *max_avail = hole_size; + if (key.offset > search_start) { + hole_size = key.offset - search_start; - if (key.offset > last_byte && - hole_size >= num_bytes) { - *start = last_byte; - goto check_pending; + if (hole_size > max_hole_size) { + max_hole_start = search_start; + max_hole_size = hole_size; + } + + /* + * If this free space is greater than which we need, + * it must be the max free space that we have found + * until now, so max_hole_start must point to the start + * of this free space and the length of this free space + * is stored in max_hole_size. Thus, we return + * max_hole_start and max_hole_size and go back to the + * caller. + */ + if (hole_size >= num_bytes) { + ret = 0; + goto out; } } - if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY) - goto next; - start_found = 1; dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent); - last_byte = key.offset + btrfs_dev_extent_length(l, dev_extent); + extent_end = key.offset + btrfs_dev_extent_length(l, + dev_extent); + if (extent_end > search_start) + search_start = extent_end; next: path->slots[0]++; cond_resched(); } -check_pending: - /* we have to make sure we didn't find an extent that has already - * been allocated by the map tree or the original allocation - */ - BUG_ON(*start < search_start); - if (*start + num_bytes > search_end) { - ret = -ENOSPC; - goto error; + hole_size = search_end- search_start; + if (hole_size > max_hole_size) { + max_hole_start = search_start; + max_hole_size = hole_size; } - /* check for pending inserts here */ - ret = 0; -error: + /* See above. */ + if (hole_size < num_bytes) + ret = -ENOSPC; + else + ret = 0; + +out: btrfs_free_path(path); +error: + *start = max_hole_start; + if (len && max_hole_size > *len) + *len = max_hole_size; return ret; }