From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C7EDC07E99 for ; Tue, 6 Jul 2021 01:38:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C9D661289 for ; Tue, 6 Jul 2021 01:38:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229811AbhGFBlM (ORCPT ); Mon, 5 Jul 2021 21:41:12 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:9476 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229740AbhGFBlL (ORCPT ); Mon, 5 Jul 2021 21:41:11 -0400 Received: from dggeme752-chm.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GJlVd1HsGzZjLr; Tue, 6 Jul 2021 09:35:21 +0800 (CST) Received: from [10.174.178.134] (10.174.178.134) by dggeme752-chm.china.huawei.com (10.3.19.98) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Tue, 6 Jul 2021 09:38:31 +0800 Subject: Re: [PATCH -v2] ext4: inline jbd2_journal_[un]register_shrinker() To: Theodore Ts'o , Ext4 Developers List CC: Jan Kara , Sachin Sant , Jon Hunter References: <3acc3ee6-3a3d-3b26-7580-b20955270913@huawei.com> <20210705145025.3363130-1-tytso@mit.edu> From: Zhang Yi Message-ID: Date: Tue, 6 Jul 2021 09:38:31 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 MIME-Version: 1.0 In-Reply-To: <20210705145025.3363130-1-tytso@mit.edu> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.134] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggeme752-chm.china.huawei.com (10.3.19.98) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On 2021/7/5 22:50, Theodore Ts'o wrote: > The function jbd2_journal_unregister_shrinker() was getting called > twice when the file system was getting unmounted. On Power and ARM > platforms this was causing kernel crash when unmounting the file > system, when a percpu_counter was destroyed twice. > > Fix this by removing jbd2_journal_[un]register_shrinker() functions, > and inlining the shrinker setup and teardown into > journal_init_common() and jbd2_journal_destroy(). This means that > ext4 and ocfs2 now no longer need to know about registering and > unregistering jbd2's shrinker. > > Also, while we're at it, rename the percpu counter from > j_jh_shrink_count to j_checkpoint_jh_count, since this makes it > clearer what this counter is intended to track. > > Fixes: 4ba3fcdde7e3 ("jbd2,ext4: add a shrinker to release checkpointed buffers") > Reported-by: Jon Hunter > Reported-by: Sachin Sant > Tested-by: Sachin Sant > Reviewed-by: Jan Kara > Signed-off-by: Theodore Ts'o This patch looks good to me. Reviewed-by: Zhang Yi Thanks, Yi. > --- > fs/ext4/super.c | 8 --- > fs/jbd2/checkpoint.c | 4 +- > fs/jbd2/journal.c | 149 +++++++++++++++++-------------------------- > include/linux/jbd2.h | 6 +- > 4 files changed, 64 insertions(+), 103 deletions(-) > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index b8ff0399e171..dfa09a277b56 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -1184,7 +1184,6 @@ static void ext4_put_super(struct super_block *sb) > ext4_unregister_sysfs(sb); > > if (sbi->s_journal) { > - jbd2_journal_unregister_shrinker(sbi->s_journal); > aborted = is_journal_aborted(sbi->s_journal); > err = jbd2_journal_destroy(sbi->s_journal); > sbi->s_journal = NULL; > @@ -5176,7 +5175,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) > sbi->s_ea_block_cache = NULL; > > if (sbi->s_journal) { > - jbd2_journal_unregister_shrinker(sbi->s_journal); > jbd2_journal_destroy(sbi->s_journal); > sbi->s_journal = NULL; > } > @@ -5502,12 +5500,6 @@ static int ext4_load_journal(struct super_block *sb, > ext4_commit_super(sb); > } > > - err = jbd2_journal_register_shrinker(journal); > - if (err) { > - EXT4_SB(sb)->s_journal = NULL; > - goto err_out; > - } > - > return 0; > > err_out: > diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c > index 51d1eb2ffeb9..746132998c57 100644 > --- a/fs/jbd2/checkpoint.c > +++ b/fs/jbd2/checkpoint.c > @@ -701,7 +701,7 @@ int __jbd2_journal_remove_checkpoint(struct journal_head *jh) > > __buffer_unlink(jh); > jh->b_cp_transaction = NULL; > - percpu_counter_dec(&journal->j_jh_shrink_count); > + percpu_counter_dec(&journal->j_checkpoint_jh_count); > jbd2_journal_put_journal_head(jh); > > /* Is this transaction empty? */ > @@ -764,7 +764,7 @@ void __jbd2_journal_insert_checkpoint(struct journal_head *jh, > jh->b_cpnext->b_cpprev = jh; > } > transaction->t_checkpoint_list = jh; > - percpu_counter_inc(&transaction->t_journal->j_jh_shrink_count); > + percpu_counter_inc(&transaction->t_journal->j_checkpoint_jh_count); > } > > /* > diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c > index 152880c298ca..35302bc192eb 100644 > --- a/fs/jbd2/journal.c > +++ b/fs/jbd2/journal.c > @@ -1283,6 +1283,48 @@ static int jbd2_min_tag_size(void) > return sizeof(journal_block_tag_t) - 4; > } > > +/** > + * jbd2_journal_shrink_scan() > + * > + * Scan the checkpointed buffer on the checkpoint list and release the > + * journal_head. > + */ > +static unsigned long jbd2_journal_shrink_scan(struct shrinker *shrink, > + struct shrink_control *sc) > +{ > + journal_t *journal = container_of(shrink, journal_t, j_shrinker); > + unsigned long nr_to_scan = sc->nr_to_scan; > + unsigned long nr_shrunk; > + unsigned long count; > + > + count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count); > + trace_jbd2_shrink_scan_enter(journal, sc->nr_to_scan, count); > + > + nr_shrunk = jbd2_journal_shrink_checkpoint_list(journal, &nr_to_scan); > + > + count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count); > + trace_jbd2_shrink_scan_exit(journal, nr_to_scan, nr_shrunk, count); > + > + return nr_shrunk; > +} > + > +/** > + * jbd2_journal_shrink_count() > + * > + * Count the number of checkpoint buffers on the checkpoint list. > + */ > +static unsigned long jbd2_journal_shrink_count(struct shrinker *shrink, > + struct shrink_control *sc) > +{ > + journal_t *journal = container_of(shrink, journal_t, j_shrinker); > + unsigned long count; > + > + count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count); > + trace_jbd2_shrink_count(journal, sc->nr_to_scan, count); > + > + return count; > +} > + > /* > * Management for journal control blocks: functions to create and > * destroy journal_t structures, and to initialise and read existing > @@ -1361,9 +1403,23 @@ static journal_t *journal_init_common(struct block_device *bdev, > journal->j_sb_buffer = bh; > journal->j_superblock = (journal_superblock_t *)bh->b_data; > > + journal->j_shrink_transaction = NULL; > + journal->j_shrinker.scan_objects = jbd2_journal_shrink_scan; > + journal->j_shrinker.count_objects = jbd2_journal_shrink_count; > + journal->j_shrinker.seeks = DEFAULT_SEEKS; > + journal->j_shrinker.batch = journal->j_max_transaction_buffers; > + > + if (percpu_counter_init(&journal->j_checkpoint_jh_count, 0, GFP_KERNEL)) > + goto err_cleanup; > + > + if (register_shrinker(&journal->j_shrinker)) { > + percpu_counter_destroy(&journal->j_checkpoint_jh_count); > + goto err_cleanup; > + } > return journal; > > err_cleanup: > + brelse(journal->j_sb_buffer); > kfree(journal->j_wbuf); > jbd2_journal_destroy_revoke(journal); > kfree(journal); > @@ -2050,93 +2106,6 @@ int jbd2_journal_load(journal_t *journal) > return -EIO; > } > > -/** > - * jbd2_journal_shrink_scan() > - * > - * Scan the checkpointed buffer on the checkpoint list and release the > - * journal_head. > - */ > -static unsigned long jbd2_journal_shrink_scan(struct shrinker *shrink, > - struct shrink_control *sc) > -{ > - journal_t *journal = container_of(shrink, journal_t, j_shrinker); > - unsigned long nr_to_scan = sc->nr_to_scan; > - unsigned long nr_shrunk; > - unsigned long count; > - > - count = percpu_counter_read_positive(&journal->j_jh_shrink_count); > - trace_jbd2_shrink_scan_enter(journal, sc->nr_to_scan, count); > - > - nr_shrunk = jbd2_journal_shrink_checkpoint_list(journal, &nr_to_scan); > - > - count = percpu_counter_read_positive(&journal->j_jh_shrink_count); > - trace_jbd2_shrink_scan_exit(journal, nr_to_scan, nr_shrunk, count); > - > - return nr_shrunk; > -} > - > -/** > - * jbd2_journal_shrink_count() > - * > - * Count the number of checkpoint buffers on the checkpoint list. > - */ > -static unsigned long jbd2_journal_shrink_count(struct shrinker *shrink, > - struct shrink_control *sc) > -{ > - journal_t *journal = container_of(shrink, journal_t, j_shrinker); > - unsigned long count; > - > - count = percpu_counter_read_positive(&journal->j_jh_shrink_count); > - trace_jbd2_shrink_count(journal, sc->nr_to_scan, count); > - > - return count; > -} > - > -/** > - * jbd2_journal_register_shrinker() > - * @journal: Journal to act on. > - * > - * Init a percpu counter to record the checkpointed buffers on the checkpoint > - * list and register a shrinker to release their journal_head. > - */ > -int jbd2_journal_register_shrinker(journal_t *journal) > -{ > - int err; > - > - journal->j_shrink_transaction = NULL; > - > - err = percpu_counter_init(&journal->j_jh_shrink_count, 0, GFP_KERNEL); > - if (err) > - return err; > - > - journal->j_shrinker.scan_objects = jbd2_journal_shrink_scan; > - journal->j_shrinker.count_objects = jbd2_journal_shrink_count; > - journal->j_shrinker.seeks = DEFAULT_SEEKS; > - journal->j_shrinker.batch = journal->j_max_transaction_buffers; > - > - err = register_shrinker(&journal->j_shrinker); > - if (err) { > - percpu_counter_destroy(&journal->j_jh_shrink_count); > - return err; > - } > - > - return 0; > -} > -EXPORT_SYMBOL(jbd2_journal_register_shrinker); > - > -/** > - * jbd2_journal_unregister_shrinker() > - * @journal: Journal to act on. > - * > - * Unregister the checkpointed buffer shrinker and destroy the percpu counter. > - */ > -void jbd2_journal_unregister_shrinker(journal_t *journal) > -{ > - percpu_counter_destroy(&journal->j_jh_shrink_count); > - unregister_shrinker(&journal->j_shrinker); > -} > -EXPORT_SYMBOL(jbd2_journal_unregister_shrinker); > - > /** > * jbd2_journal_destroy() - Release a journal_t structure. > * @journal: Journal to act on. > @@ -2209,8 +2178,10 @@ int jbd2_journal_destroy(journal_t *journal) > brelse(journal->j_sb_buffer); > } > > - jbd2_journal_unregister_shrinker(journal); > - > + if (journal->j_shrinker.flags & SHRINKER_REGISTERED) { > + percpu_counter_destroy(&journal->j_checkpoint_jh_count); > + unregister_shrinker(&journal->j_shrinker); > + } > if (journal->j_proc_entry) > jbd2_stats_proc_exit(journal); > iput(journal->j_inode); > diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h > index 6cc035321562..fd933c45281a 100644 > --- a/include/linux/jbd2.h > +++ b/include/linux/jbd2.h > @@ -918,11 +918,11 @@ struct journal_s > struct shrinker j_shrinker; > > /** > - * @j_jh_shrink_count: > + * @j_checkpoint_jh_count: > * > * Number of journal buffers on the checkpoint list. [j_list_lock] > */ > - struct percpu_counter j_jh_shrink_count; > + struct percpu_counter j_checkpoint_jh_count; > > /** > * @j_shrink_transaction: > @@ -1556,8 +1556,6 @@ extern int jbd2_journal_set_features > (journal_t *, unsigned long, unsigned long, unsigned long); > extern void jbd2_journal_clear_features > (journal_t *, unsigned long, unsigned long, unsigned long); > -extern int jbd2_journal_register_shrinker(journal_t *journal); > -extern void jbd2_journal_unregister_shrinker(journal_t *journal); > extern int jbd2_journal_load (journal_t *journal); > extern int jbd2_journal_destroy (journal_t *); > extern int jbd2_journal_recover (journal_t *journal); >