From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8104E4A8A26; Thu, 3 Sep 2026 12:43:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788439388; cv=none; b=POMZ+DHZtq6dS6bPBLxc3Umyd6I+7ZwE4PwseopQbGK+R+7gk5KOVwWSaZ4rBYq63IqdB0m0tjU3tZi8tLyZwoAMa+LEhNFX/8Us2F2YZxqp0jmKQ7ac7djnbesMANWCa+tBmOzYVNRkzOrpHXXy4bPz0U28cjV1TocAO/U6FKY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788439388; c=relaxed/simple; bh=VbCw+8IbXLyFsc9KhNZnWsHGtYDn9eiqHe2DWBDFwto=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FJVQwlW+VVeUxdzDBS1sGElT5nSrYHrAX6Oep0sCQHLr0Qf0RbMLTIn6j9h81gFnmY8TTYMu/8d00drZhx0bXVlzcgZddTNXvLpSCk1Z/WlXJo/F1a1cybrIqvD7PCvHwCmbNCnB3mqqQ1jbW6ruqO2YB19kYUzgcIEm3VhmTPg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.198]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4hbK402XgBzYQtth; Thu, 3 Sep 2026 20:42:08 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id 3A31140B57; Thu, 3 Sep 2026 20:42:51 +0800 (CST) Received: from huaweicloud.com (unknown [10.50.85.155]) by APP1 (Coremail) with UTF8SMTPSA id cCh0CgA3HglDa5lqAJVrAg--.30843S12; Thu, 03 Sep 2026 20:42:50 +0800 (CST) From: Zhang Yi To: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, libaokun@linux.alibaba.com, jack@suse.cz, ojaswin@linux.ibm.com, ritesh.list@gmail.com, djwong@kernel.org, hch@infradead.org, yi.zhang@huawei.com, yi.zhang@huaweicloud.com, yizhang089@gmail.com, chengzhihao1@huawei.com, yangerkun@huawei.com, wangkefeng.wang@huawei.com, yukuai@fnnas.com Subject: [PATCH v6 08/31] ext4: avoid unnecessary transaction in ext4_map_blocks() for unwritten extents Date: Thu, 3 Sep 2026 20:35:20 +0800 Message-ID: <20260903123543.2302999-9-yi.zhang@huaweicloud.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260903123543.2302999-1-yi.zhang@huaweicloud.com> References: <20260903123543.2302999-1-yi.zhang@huaweicloud.com> 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-CM-TRANSID:cCh0CgA3HglDa5lqAJVrAg--.30843S12 X-Coremail-Antispam: 1UD129KBjvJXoW7CFW8Jw1fuFWkJFyUJFWUArb_yoW8Cw1fpa sayr1rCF40g343WayfAF4jgFWak34fKFWDuF48Kryjva43Kr1SgF10gF1rGFWUKrWfAay5 XFWjkw18C3Z5CrDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUmq14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_Gr0_Xr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26F4UJVW0owA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE 3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2I x0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8 JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2Y2 ka0xkIwI1lc7CjxVAaw2AFwI0_GFv_Wryl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Y z7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zV AF1VAY17CE14v26r4a6rW5MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_JFI_Gr1l IxAIcVC0I7IYx2IY6xkF7I0E14v26r4UJVWxJr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r 1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr1j6F4UJbIY CTnIWIevJa73UjIFyTuYvjTR_nYFDUUUU X-CM-SenderInfo: d1lo6xhdqjqx5xdzvxpfor3voofrz/ From: Zhang Yi When ext4_map_blocks() finds an unwritten extent in the extent cache and the caller is willing to accept unwritten extents without conversion, there is no need to start a journal transaction since no metadata update is required. This avoids unnecessary transaction overhead in the upcoming iomap writeback path when overwriting already-allocated unwritten extents. One thing to be careful about, as the comment in ext4_map_blocks() states, if the flags contain EXT4_GET_BLOCKS_CREATE, the function will mark @map as mapped. Signed-off-by: Zhang Yi --- fs/ext4/inode.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index c9dea4ca5caf..7a5c74af8ff3 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -809,14 +809,23 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode, * Note that if blocks have been preallocated * ext4_ext_map_blocks() returns with buffer head unmapped */ - if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) + if (retval > 0) { /* - * If we need to convert extent to unwritten - * we continue and do the actual work in - * ext4_ext_map_blocks() + * If we need to convert written extent to unwritten or + * convert unwritten extent to written, continue and do + * the actual work in ext4_ext_map_blocks(). */ - if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN)) + if (map->m_flags & EXT4_MAP_MAPPED && + !(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN)) goto out_handle; + if (map->m_flags & EXT4_MAP_UNWRITTEN && + (flags & EXT4_GET_BLOCKS_UNWRIT_EXT) && + !(flags & EXT4_GET_BLOCKS_CONVERT)) { + /* Contains EXT4_GET_BLOCKS_CREATE - mark mapped. */ + map->m_flags |= EXT4_MAP_MAPPED; + goto out_handle; + } + } if (!handle) { handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, -- 2.52.0