{"id":2190726,"url":"http://patchwork.ozlabs.org/api/1.2/patches/2190726/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-ext4/patch/20260130031232.60780-2-me@linux.beauty/","project":{"id":8,"url":"http://patchwork.ozlabs.org/api/1.2/projects/8/?format=json","name":"Linux ext4 filesystem development","link_name":"linux-ext4","list_id":"linux-ext4.vger.kernel.org","list_email":"linux-ext4@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260130031232.60780-2-me@linux.beauty>","list_archive_url":null,"date":"2026-01-30T03:12:30","name":"[1/3] jbd2: use READ_ONCE for lockless jinode reads","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"ce3ea2ad910b7291ce9f256a2e72d389ec2e247b","submitter":{"id":84264,"url":"http://patchwork.ozlabs.org/api/1.2/people/84264/?format=json","name":"Li Chen","email":"me@linux.beauty"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-ext4/patch/20260130031232.60780-2-me@linux.beauty/mbox/","series":[{"id":490324,"url":"http://patchwork.ozlabs.org/api/1.2/series/490324/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-ext4/list/?series=490324","date":"2026-01-30T03:12:31","name":"jbd2/ext4/ocfs2: READ_ONCE for lockless jinode reads","version":1,"mbox":"http://patchwork.ozlabs.org/series/490324/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2190726/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2190726/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-ext4@vger.kernel.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","patchwork-incoming@ozlabs.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=linux.beauty 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helo=sea.lore.kernel.org;\n envelope-from=linux-ext4+bounces-13434-patchwork-incoming=ozlabs.org@vger.kernel.org;\n receiver=ozlabs.org) smtp.mailfrom=vger.kernel.org","i=2; smtp.subspace.kernel.org;\n dmarc=none (p=none dis=none) header.from=linux.beauty;\n spf=pass smtp.mailfrom=linux.beauty;\n dkim=pass (1024-bit key) header.d=linux.beauty header.i=me@linux.beauty\n header.b=BqtTZLPG; arc=pass smtp.client-ip=136.143.188.112","i=1; mx.zohomail.com;\n\tdkim=pass header.i=linux.beauty;\n\tspf=pass smtp.mailfrom=me@linux.beauty;\n\tdmarc=pass header.from="],"DKIM-Signature":"v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1769742778;\n\ts=zmail; d=linux.beauty; i=me@linux.beauty;\n\th=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To;\n\tbh=flqovzkqjGriKlWs8tgUbIAnm7IIBuluTOQuNQzOASc=;\n\tb=BqtTZLPGaO5claLf1CBC1TambgYd8F3h8P56GlMmGLJcq6b5imWkesdGx0jGaDJb\n\tB44F0NSTlmS3mUgA7+nufY5xhfo1i9uKeG1pjCCksNr53TY6Et/ol2o+6uOuFr4T4zt\n\txcw/CHiJO5o5mFlRgcIFy5RbUrmuEasOTjwinXQw=","From":"Li Chen ","To":"\"Theodore Ts'o\" ,\n\tJan Kara ,\n\tlinux-ext4@vger.kernel.org,\n\tlinux-kernel@vger.kernel.org","Cc":"Li Chen ","Subject":"[PATCH 1/3] jbd2: use READ_ONCE for lockless jinode reads","Date":"Fri, 30 Jan 2026 11:12:30 +0800","Message-ID":"<20260130031232.60780-2-me@linux.beauty>","X-Mailer":"git-send-email 2.52.0","In-Reply-To":"<20260130031232.60780-1-me@linux.beauty>","References":"<20260130031232.60780-1-me@linux.beauty>","Precedence":"bulk","X-Mailing-List":"linux-ext4@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","X-ZohoMailClient":"External","X-Spam-Status":"No, score=-1.2 required=5.0 tests=ARC_SIGNED,ARC_VALID,\n\tDKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DMARC_MISSING,\n\tHEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,\n\tSPF_PASS autolearn=disabled version=4.0.1","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on gandalf.ozlabs.org"},"content":"jbd2_inode fields are updated under journal->j_list_lock, but some\npaths read them without holding the lock (e.g. fast commit\nhelpers and the ordered truncate fast path).\n\nUse READ_ONCE() for these lockless reads to correct the\nconcurrency assumptions.\n\nSuggested-by: Jan Kara \nSigned-off-by: Li Chen \n---\n fs/jbd2/commit.c | 39 ++++++++++++++++++++++++++++++++-------\n fs/jbd2/transaction.c | 2 +-\n 2 files changed, 33 insertions(+), 8 deletions(-)","diff":"diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c\nindex 7203d2d2624d..3347d75da2f8 100644\n--- a/fs/jbd2/commit.c\n+++ b/fs/jbd2/commit.c\n@@ -180,7 +180,13 @@ static int journal_wait_on_commit_record(journal_t *journal,\n /* Send all the data buffers related to an inode */\n int jbd2_submit_inode_data(journal_t *journal, struct jbd2_inode *jinode)\n {\n-\tif (!jinode || !(jinode->i_flags & JI_WRITE_DATA))\n+\tunsigned long flags;\n+\n+\tif (!jinode)\n+\t\treturn 0;\n+\n+\tflags = READ_ONCE(jinode->i_flags);\n+\tif (!(flags & JI_WRITE_DATA))\n \t\treturn 0;\n \n \ttrace_jbd2_submit_inode_data(jinode->i_vfs_inode);\n@@ -191,12 +197,30 @@ EXPORT_SYMBOL(jbd2_submit_inode_data);\n \n int jbd2_wait_inode_data(journal_t *journal, struct jbd2_inode *jinode)\n {\n-\tif (!jinode || !(jinode->i_flags & JI_WAIT_DATA) ||\n-\t\t!jinode->i_vfs_inode || !jinode->i_vfs_inode->i_mapping)\n+\tstruct address_space *mapping;\n+\tstruct inode *inode;\n+\tunsigned long flags;\n+\tloff_t start, end;\n+\n+\tif (!jinode)\n+\t\treturn 0;\n+\n+\tflags = READ_ONCE(jinode->i_flags);\n+\tif (!(flags & JI_WAIT_DATA))\n+\t\treturn 0;\n+\n+\tinode = READ_ONCE(jinode->i_vfs_inode);\n+\tif (!inode)\n+\t\treturn 0;\n+\n+\tmapping = inode->i_mapping;\n+\tstart = READ_ONCE(jinode->i_dirty_start);\n+\tend = READ_ONCE(jinode->i_dirty_end);\n+\n+\tif (!mapping)\n \t\treturn 0;\n \treturn filemap_fdatawait_range_keep_errors(\n-\t\tjinode->i_vfs_inode->i_mapping, jinode->i_dirty_start,\n-\t\tjinode->i_dirty_end);\n+\t\tmapping, start, end);\n }\n EXPORT_SYMBOL(jbd2_wait_inode_data);\n \n@@ -240,10 +264,11 @@ static int journal_submit_data_buffers(journal_t *journal,\n int jbd2_journal_finish_inode_data_buffers(struct jbd2_inode *jinode)\n {\n \tstruct address_space *mapping = jinode->i_vfs_inode->i_mapping;\n+\tloff_t start = READ_ONCE(jinode->i_dirty_start);\n+\tloff_t end = READ_ONCE(jinode->i_dirty_end);\n \n \treturn filemap_fdatawait_range_keep_errors(mapping,\n-\t\t\t\t\t\t jinode->i_dirty_start,\n-\t\t\t\t\t\t jinode->i_dirty_end);\n+\t\t\t\t\t\t start, end);\n }\n \n /*\ndiff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c\nindex dca4b5d8aaaa..302b2090eea7 100644\n--- a/fs/jbd2/transaction.c\n+++ b/fs/jbd2/transaction.c\n@@ -2739,7 +2739,7 @@ int jbd2_journal_begin_ordered_truncate(journal_t *journal,\n \tint ret = 0;\n \n \t/* This is a quick check to avoid locking if not necessary */\n-\tif (!jinode->i_transaction)\n+\tif (!READ_ONCE(jinode->i_transaction))\n \t\tgoto out;\n \t/* Locks are here just to force reading of recent values, it is\n \t * enough that the transaction was not committing before we started\n","prefixes":["1/3"]}