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 39D2C225402; Wed, 23 Apr 2025 09:03:30 +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=1745399013; cv=none; b=NWx9dfh6H7qI9AG/HCqRFzxxE3ILqerYgGg9+8zh2j8BN9v/DPDbQcFEoCeYp5gDuz8plPoBvGKO39J5RdOVACLiIBIZ7HbPYqdHRd7w2fySqrlvYVUUr4qq/uFZf85m4KwL9lSdBUmGXtt/31iEJVrg8BZWgMZmhgW/x5dHOCQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745399013; c=relaxed/simple; bh=WtUwSHuTeaBvjZinOcJftwdviR//LrgtyCp/b0uWmXM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sSgG6N+AeETnGdAZX7lHwCqhpbI+XdKsi94cPZRU3/nH2sefoIXITgHZUPCnHNZewKPnwdwWxvBczjaZLIlFdnruLmgux/n7kTm+29umAqHCnpF4nzBwQ9zSIw5LJTjJzAublKVPT/wIt8k4yDjl4D1gXBpoeTIy3Fs/ZS44b/k= 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 [172.19.163.216]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4ZjCmw5vHtz4f3lDN; Wed, 23 Apr 2025 17:02:56 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id 4E57F1A1C77; Wed, 23 Apr 2025 17:03:22 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.112.188]) by APP3 (Coremail) with SMTP id _Ch0CgAXacPQrAhoJkGrKA--.8976S8; Wed, 23 Apr 2025 17:03:22 +0800 (CST) From: Zhang Yi To: linux-ext4@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, yi.zhang@huawei.com, yi.zhang@huaweicloud.com, libaokun1@huawei.com, yukuai3@huawei.com, yangerkun@huawei.com Subject: [PATCH 4/9] ext4: prevent stale extent cache entries caused by concurrent fiemap Date: Wed, 23 Apr 2025 16:52:52 +0800 Message-ID: <20250423085257.122685-5-yi.zhang@huaweicloud.com> X-Mailer: git-send-email 2.46.1 In-Reply-To: <20250423085257.122685-1-yi.zhang@huaweicloud.com> References: <20250423085257.122685-1-yi.zhang@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_Ch0CgAXacPQrAhoJkGrKA--.8976S8 X-Coremail-Antispam: 1UD129KBjvJXoW7ZF13Kr4ruF1rWF17Ww43trb_yoW8KF13pr sI9F98Gr4rX3s5WrZ2qFW8Za4Ska48GrWjy3yfG3ZrZFyUJr40gF1rKFyFyF1Fg3ykAw4Y qF40kw1UGa4Uu3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUmI14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUXVWUAwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4U M4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2 kIc2xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkE bVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67 AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI 42IY6xIIjxv20xvEc7CjxVAFwI0_Cr0_Gr1UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCw CI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnI WIevJa73UjIFyTuYvjfUo73vUUUUU X-CM-SenderInfo: d1lo6xhdqjqx5xdzvxpfor3voofrz/ From: Zhang Yi The ext4_fiemap() currently invokes ext4_ext_precache() and iomap_fiemap() to preload the extent cache and query mapping information without holding the inode's i_rwsem. This can result in stale extent cache entries when competing with operations such as ext4_collapse_range() which calls ext4_ext_remove_space() or ext4_ext_shift_extents(). The problem arises when ext4_ext_remove_space() temporarily releases i_data_sem due to insufficient journal credits. During this interval, a concurrent ext4_fiemap() may cache extent entries that are about to be deleted. As a result, these cached entries become stale and inconsistent with the actual extents. Loading the extents cache without holding the inode's i_rwsem or the mapping's invalidate_lock is not permitted besides during the writeback. Fix this by holding the i_rwsem in ext4_fiemap(). Signed-off-by: Zhang Yi --- fs/ext4/extents.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 8a5724b2dc51..3adf05fbdd59 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4963,10 +4963,11 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, { int error = 0; + inode_lock_shared(inode); if (fieinfo->fi_flags & FIEMAP_FLAG_CACHE) { error = ext4_ext_precache(inode); if (error) - return error; + goto unlock; fieinfo->fi_flags &= ~FIEMAP_FLAG_CACHE; } @@ -4977,15 +4978,19 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, */ error = ext4_fiemap_check_ranges(inode, start, &len); if (error) - return error; + goto unlock; if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) { fieinfo->fi_flags &= ~FIEMAP_FLAG_XATTR; - return iomap_fiemap(inode, fieinfo, start, len, - &ext4_iomap_xattr_ops); + error = iomap_fiemap(inode, fieinfo, start, len, + &ext4_iomap_xattr_ops); + } else { + error = iomap_fiemap(inode, fieinfo, start, len, + &ext4_iomap_report_ops); } - - return iomap_fiemap(inode, fieinfo, start, len, &ext4_iomap_report_ops); +unlock: + inode_unlock_shared(inode); + return error; } int ext4_get_es_cache(struct inode *inode, struct fiemap_extent_info *fieinfo, -- 2.46.1