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[174.109.172.136]) by smtp.gmail.com with ESMTPSA id r17sm43000qtc.22.2020.10.15.11.26.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Oct 2020 11:26:14 -0700 (PDT) From: Josef Bacik To: linux-btrfs@vger.kernel.org, kernel-team@fb.com Subject: [PATCH 6/6] btrfs: stop running all delayed refs during snapshot Date: Thu, 15 Oct 2020 14:26:02 -0400 Message-Id: <59571e7b8eb8b93bab529addf4a0d91daa00b2d7.1602786206.git.josef@toxicpanda.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This was added a very long time ago to work around issues with delayed refs and with qgroups. Both of these issues have since been properly fixed, so all this does is cause a lot of lock contention with anybody else who is running delayed refs. Signed-off-by: Josef Bacik --- fs/btrfs/transaction.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index f4d55ac7f8f2..fc8f12e609a2 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1189,10 +1189,6 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans) btrfs_tree_unlock(eb); free_extent_buffer(eb); - if (ret) - return ret; - - ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); if (ret) return ret; @@ -1210,10 +1206,6 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans) if (ret) return ret; - /* run_qgroups might have added some more refs */ - ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); - if (ret) - return ret; again: while (!list_empty(&fs_info->dirty_cowonly_roots)) { struct btrfs_root *root; @@ -1228,15 +1220,24 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans) ret = update_cowonly_root(trans, root); if (ret) return ret; - ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); - if (ret) - return ret; } + /* Now flush any delayed refs generated by updating all of the roots. */ + ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); + if (ret) + return ret; + while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) { ret = btrfs_write_dirty_block_groups(trans); if (ret) return ret; + + /* + * We're writing the dirty block groups, which could generate + * delayed refs, which could generate more dirty block groups, + * so we want to keep this flushing in this loop to make sure + * everything gets run. + */ ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); if (ret) return ret; -- 2.24.1