From patchwork Thu Jun 11 15:20:59 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Mahoney X-Patchwork-Id: 6589211 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 47EB39F2F4 for ; Thu, 11 Jun 2015 15:21:25 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 55EEF2058A for ; Thu, 11 Jun 2015 15:21:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 448552063F for ; Thu, 11 Jun 2015 15:21:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752960AbbFKPVP (ORCPT ); Thu, 11 Jun 2015 11:21:15 -0400 Received: from cantor2.suse.de ([195.135.220.15]:60018 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751963AbbFKPVL (ORCPT ); Thu, 11 Jun 2015 11:21:11 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id DAE25ADC6 for ; Thu, 11 Jun 2015 15:21:09 +0000 (UTC) Received: by starscream.home.jeffm.io (Postfix, from userid 1000) id 282A486D0F; Thu, 11 Jun 2015 11:21:05 -0400 (EDT) From: jeffm@suse.com To: linux-btrfs@vger.kernel.org Cc: Jeff Mahoney Subject: [PATCH 1/4] btrfs: skip superblocks during discard Date: Thu, 11 Jun 2015 11:20:59 -0400 Message-Id: <1434036062-21597-2-git-send-email-jeffm@suse.com> X-Mailer: git-send-email 1.8.4.5 In-Reply-To: <1434036062-21597-1-git-send-email-jeffm@suse.com> References: <1434036062-21597-1-git-send-email-jeffm@suse.com> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Jeff Mahoney Btrfs doesn't track superblocks with extent records so there is nothing persistent on-disk to indicate that those blocks are in use. We track the superblocks in memory to ensure they don't get used by removing them from the free space cache when we load a block group from disk. Prior to 47ab2a6c6a (Btrfs: remove empty block groups automatically), that was fine since the block group would never be reclaimed so the superblock was always safe. Once we started removing the empty block groups, we were protected by the fact that discards weren't being properly issued for unused space either via FITRIM or -odiscard. The block groups were still being released, but the blocks remained on disk. In order to properly discard unused block groups, we need to filter out the superblocks from the discard range. Superblocks are located at fixed locations on each device, so it makes sense to filter them out in btrfs_issue_discard, which is used by both -odiscard and FITRIM. Signed-off-by: Jeff Mahoney --- fs/btrfs/extent-tree.c | 50 ++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 44 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 0ec3acd..75d0226 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -1884,10 +1884,47 @@ static int remove_extent_backref(struct btrfs_trans_handle *trans, return ret; } -static int btrfs_issue_discard(struct block_device *bdev, - u64 start, u64 len) +#define in_range(b, first, len) ((b) >= (first) && (b) < (first) + (len)) +static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len, + u64 *discarded_bytes) { - return blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_NOFS, 0); + u64 skipped = 0; + u64 bytes_left = len; + int ret = 0 , j; + + *discarded_bytes = 0; + + /* Skip any superblocks on this device. */ + for (j = 0; j < BTRFS_SUPER_MIRROR_MAX; j++) { + u64 sb_offset = btrfs_sb_offset(j); + u64 size = sb_offset - start; + + if (!in_range(sb_offset, start, bytes_left)) + continue; + + if (size) { + ret = blkdev_issue_discard(bdev, start >> 9, size >> 9, + GFP_NOFS, 0); + if (!ret) + *discarded_bytes += size; + else if (ret != -EOPNOTSUPP) + return ret; + } + + start = sb_offset + BTRFS_SUPER_INFO_SIZE; + if (start > len) + start = len; + bytes_left = len - start; + skipped += BTRFS_SUPER_INFO_SIZE; + } + + if (bytes_left) { + ret = blkdev_issue_discard(bdev, start >> 9, bytes_left >> 9, + GFP_NOFS, 0); + if (!ret) + *discarded_bytes += bytes_left; + } + return ret; } int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr, @@ -1906,16 +1943,17 @@ int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr, struct btrfs_bio_stripe *stripe = bbio->stripes; int i; - for (i = 0; i < bbio->num_stripes; i++, stripe++) { + u64 bytes; + if (!stripe->dev->can_discard) continue; ret = btrfs_issue_discard(stripe->dev->bdev, stripe->physical, - stripe->length); + stripe->length, &bytes); if (!ret) - discarded_bytes += stripe->length; + discarded_bytes += bytes; else if (ret != -EOPNOTSUPP) break; /* Logic errors or -ENOMEM, or -EIO but I don't know how that could happen JDM */