From patchwork Fri Dec 7 13:23:32 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 10718125 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 92A291750 for ; Fri, 7 Dec 2018 13:23:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7CDCF292C3 for ; Fri, 7 Dec 2018 13:23:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6CC26294C2; Fri, 7 Dec 2018 13:23:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E1F08292C3 for ; Fri, 7 Dec 2018 13:23:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726014AbeLGNXh (ORCPT ); Fri, 7 Dec 2018 08:23:37 -0500 Received: from mail.kernel.org ([198.145.29.99]:57706 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725997AbeLGNXh (ORCPT ); Fri, 7 Dec 2018 08:23:37 -0500 Received: from localhost.localdomain (bl8-197-74.dsl.telepac.pt [85.241.197.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A656920837 for ; Fri, 7 Dec 2018 13:23:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544189016; bh=Q0lQcyTQXkU9XJqnPMyvrFSNClreTCjfxQQd32XRUnI=; h=From:To:Subject:Date:From; b=MeMh0bjp6pVqMTAJJ7A8mewgpS0Y0+8muHo0k2sfquaCl5zdkgBjKImzuglls6BUh PrTXYnyZsDQEg33J+IPLbD259RMPyWdRalZKKIIumzIx3elDFZ7O/XfGghKRnO3x9g Dp9h92T+Brr7flF07NIaW/ag27Z4J5fiNMrKaD1A= From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Subject: [PATCH] Btrfs: scrub, move setup of nofs contexts higher in the stack Date: Fri, 7 Dec 2018 13:23:32 +0000 Message-Id: <20181207132332.31774-1-fdmanana@kernel.org> X-Mailer: git-send-email 2.11.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Filipe Manana Since scrub workers only do memory allocation with GFP_KERNEL when they need to perform repair, we can move the recent setup of the nofs context up to scrub_handle_errored_block() instead of setting it up down the call chain at insert_full_stripe_lock() and scrub_add_page_to_wr_bio(), removing some duplicate code and comment. So the only paths for which a scrub worker can do memory allocations using GFP_KERNEL are the following: scrub_bio_end_io_worker() scrub_block_complete() scrub_handle_errored_block() lock_full_stripe() insert_full_stripe_lock() -> kmalloc with GFP_KERNEL scrub_bio_end_io_worker() scrub_block_complete() scrub_handle_errored_block() scrub_write_page_to_dev_replace() scrub_add_page_to_wr_bio() -> kzalloc with GFP_KERNEL Signed-off-by: Filipe Manana Reviewed-by: David Sterba --- Applies on top of: Btrfs: fix deadlock with memory reclaim during scrub fs/btrfs/scrub.c | 34 ++++++++++++++-------------------- 1 file changed, 14 insertions(+), 20 deletions(-) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index bbd1b36f4918..f996f4064596 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -322,7 +322,6 @@ static struct full_stripe_lock *insert_full_stripe_lock( struct rb_node *parent = NULL; struct full_stripe_lock *entry; struct full_stripe_lock *ret; - unsigned int nofs_flag; lockdep_assert_held(&locks_root->lock); @@ -342,15 +341,8 @@ static struct full_stripe_lock *insert_full_stripe_lock( /* * Insert new lock. - * - * We must use GFP_NOFS because the scrub task might be waiting for a - * worker task executing this function and in turn a transaction commit - * might be waiting the scrub task to pause (which needs to wait for all - * the worker tasks to complete before pausing). */ - nofs_flag = memalloc_nofs_save(); ret = kmalloc(sizeof(*ret), GFP_KERNEL); - memalloc_nofs_restore(nofs_flag); if (!ret) return ERR_PTR(-ENOMEM); ret->logical = fstripe_logical; @@ -842,6 +834,7 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check) int page_num; int success; bool full_stripe_locked; + unsigned int nofs_flag; static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); @@ -867,6 +860,16 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check) dev = sblock_to_check->pagev[0]->dev; /* + * We must use GFP_NOFS because the scrub task might be waiting for a + * worker task executing this function and in turn a transaction commit + * might be waiting the scrub task to pause (which needs to wait for all + * the worker tasks to complete before pausing). + * We do allocations in the workers through insert_full_stripe_lock() + * and scrub_add_page_to_wr_bio(), which happens down the call chain of + * this function. + */ + nofs_flag = memalloc_nofs_save(); + /* * For RAID5/6, race can happen for a different device scrub thread. * For data corruption, Parity and Data threads will both try * to recovery the data. @@ -875,6 +878,7 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check) */ ret = lock_full_stripe(fs_info, logical, &full_stripe_locked); if (ret < 0) { + memalloc_nofs_restore(nofs_flag); spin_lock(&sctx->stat_lock); if (ret == -ENOMEM) sctx->stat.malloc_errors++; @@ -914,7 +918,7 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check) */ sblocks_for_recheck = kcalloc(BTRFS_MAX_MIRRORS, - sizeof(*sblocks_for_recheck), GFP_NOFS); + sizeof(*sblocks_for_recheck), GFP_KERNEL); if (!sblocks_for_recheck) { spin_lock(&sctx->stat_lock); sctx->stat.malloc_errors++; @@ -1212,6 +1216,7 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check) } ret = unlock_full_stripe(fs_info, logical, full_stripe_locked); + memalloc_nofs_restore(nofs_flag); if (ret < 0) return ret; return 0; @@ -1630,19 +1635,8 @@ static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx, mutex_lock(&sctx->wr_lock); again: if (!sctx->wr_curr_bio) { - unsigned int nofs_flag; - - /* - * We must use GFP_NOFS because the scrub task might be waiting - * for a worker task executing this function and in turn a - * transaction commit might be waiting the scrub task to pause - * (which needs to wait for all the worker tasks to complete - * before pausing). - */ - nofs_flag = memalloc_nofs_save(); sctx->wr_curr_bio = kzalloc(sizeof(*sctx->wr_curr_bio), GFP_KERNEL); - memalloc_nofs_restore(nofs_flag); if (!sctx->wr_curr_bio) { mutex_unlock(&sctx->wr_lock); return -ENOMEM;