From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 14549258EC3; Tue, 23 Dec 2025 00:38:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766450331; cv=none; b=l+xxANGRIfTiVITu0W6ZvXycxxwPelgOvTQfSxQF4T/7UeWikp18TwR7QUeF9eD26voisw7JyBF3py8LGlTPj91IRtzeiCUO4I9LJAgJ/TWBvzJz0SXx6tbG/stfjTVCRAgQY+WirAuyAEtIUhm45oJofgZfuid6jr8il26Fml4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766450331; c=relaxed/simple; bh=6NB5DA8B9zQy51ODCNY5BX/Ss8k7EUgAwattRxRwjEQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=R3YOOIUjw7zcNzLuPkcYNkBoMBxSkcXEBshqIIRDIyQQkfwsPJr82a6ToAQE2V1NCxrjzFmgayVxzYQPS9y+AsvOkpV0Qqp3c5eM1bsZI5jWOjsVw1XjnmNhwBjFyp1fsgjUFbKeP7cXldAesxgqR3EyKpZFEXCiFEIUNNiBQfA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=lst.de; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=RoP3vCRa; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="RoP3vCRa" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=9qCDtCy2v3payACRaxwKUv7ePGUjjs+NfQFo3M8oXRA=; b=RoP3vCRaSI5C876WE7SFJNLYGH IZ7XbV8pmw+HOKS+5r6r3yorNXR8Hw538eUILX8mNSC+XlZvVzlUcjS+OjJkCD9OpnPkBCoBmYZ2S J77HX+sS3yKICBPDOqprBFvQatgoqvK4TNwxNfLsBXKCh0TKFopy9xHWBLoQl9f+ZEkYXOAUo4rfQ mjccEGyGZYW0JFMqekZpr0yqkCRuvkslw/GlZwhfjai8x9UiiGfCNHzDBpY6nFliJDjpQFqMCjOPV sQP2IfMz/00RBr3eDd43+fV0YdTwR7Yk7rKSAq1Jn4tYmOy50mF4skiVx/ZwJfQ4XjLGGZ2Lz3TGN yhtR6Fzg==; Received: from s58.ghokkaidofl2.vectant.ne.jp ([202.215.7.58] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vXqQJ-0000000EJ07-0YZe; Tue, 23 Dec 2025 00:38:47 +0000 From: Christoph Hellwig To: Christian Brauner Cc: Al Viro , David Sterba , Jan Kara , Mike Marshall , Martin Brandenburg , Carlos Maiolino , Stefan Roesch , Jeff Layton , linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, gfs2@lists.linux.dev, io-uring@vger.kernel.org, devel@lists.orangefs.org, linux-unionfs@vger.kernel.org, linux-mtd@lists.infradead.org, linux-xfs@vger.kernel.org, linux-nfs@vger.kernel.org Subject: [PATCH 08/11] fs: add support for non-blocking timestamp updates Date: Tue, 23 Dec 2025 09:37:51 +0900 Message-ID: <20251223003756.409543-9-hch@lst.de> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251223003756.409543-1-hch@lst.de> References: <20251223003756.409543-1-hch@lst.de> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Currently file_update_time_flags unconditionally returns -EAGAIN if any timestamp needs to be updated and IOCB_NOWAIT is passed. This makes non-blocking direct writes impossible on file systems with granular enough timestamps. Add a S_NOWAIT to ask for timestamps to not block, and return -EAGAIN in all methods for now. Signed-off-by: Christoph Hellwig Reviewed-by: Jeff Layton --- fs/fat/misc.c | 3 +++ fs/gfs2/inode.c | 3 +++ fs/inode.c | 29 ++++++++++++++++++++++++++--- fs/overlayfs/inode.c | 2 ++ fs/ubifs/file.c | 3 +++ fs/xfs/xfs_iops.c | 3 +++ include/linux/fs.h | 21 +++++++++++++++++---- 7 files changed, 57 insertions(+), 7 deletions(-) diff --git a/fs/fat/misc.c b/fs/fat/misc.c index 950da09f0961..5df3193c35f9 100644 --- a/fs/fat/misc.c +++ b/fs/fat/misc.c @@ -346,6 +346,9 @@ int fat_update_time(struct inode *inode, int flags) if (inode->i_ino == MSDOS_ROOT_INO) return 0; + if (flags & S_NOWAIT) + return -EAGAIN; + if (flags & (S_ATIME | S_CTIME | S_MTIME)) { fat_truncate_time(inode, NULL, flags); if (inode->i_sb->s_flags & SB_LAZYTIME) diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c index e08eb419347c..0dce2af533b2 100644 --- a/fs/gfs2/inode.c +++ b/fs/gfs2/inode.c @@ -2249,6 +2249,9 @@ static int gfs2_update_time(struct inode *inode, int flags) struct gfs2_holder *gh; int error; + if (flags & S_NOWAIT) + return -EAGAIN; + gh = gfs2_glock_is_locked_by_me(gl); if (gh && gl->gl_state != LM_ST_EXCLUSIVE) { gfs2_glock_dq(gh); diff --git a/fs/inode.c b/fs/inode.c index 212dab5c65ad..98a878427ecb 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -2111,6 +2111,13 @@ int inode_update_timestamps(struct inode *inode, int flags, int *dirty_flags) *dirty_flags = 0; + /* + * Non-blocking timestamp updates require an explicit opt-in from the + * file system. + */ + if ((flags & S_NOWAIT) && !(flags & S_CAN_NOWAIT_LAZYTIME)) + return -EAGAIN; + if (flags & (S_MTIME | S_CTIME | S_VERSION)) { struct timespec64 ctime = inode_get_ctime(inode); struct timespec64 mtime = inode_get_mtime(inode); @@ -2120,8 +2127,24 @@ int inode_update_timestamps(struct inode *inode, int flags, int *dirty_flags) updated |= S_CTIME; if (!timespec64_equal(&now, &mtime)) updated |= S_MTIME; - if (IS_I_VERSION(inode) && inode_maybe_inc_iversion(inode, updated)) - updated |= S_VERSION; + + /* + * Pure timestamp updates can be recorded in the inode without + * blocking by not dirtying the inode. But when the file system + * requires i_version updates, actual i_version update may block + * despite that. Error out if we'd actually have to update + * i_version or don't support lazytime. + */ + if (IS_I_VERSION(inode)) { + if (flags & S_NOWAIT) { + if (!(inode->i_sb->s_flags & SB_LAZYTIME) || + inode_iversion_need_inc(inode)) + return -EAGAIN; + } else { + if (inode_maybe_inc_iversion(inode, updated)) + updated |= S_NOWAIT; + } + } } else { now = current_time(inode); } @@ -2391,7 +2414,7 @@ static int file_update_time_flags(struct file *file, unsigned int flags) return 0; if (flags & IOCB_NOWAIT) - return -EAGAIN; + sync_mode |= S_NOWAIT; if (mnt_get_write_access_file(file)) return 0; diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index bdbf86b56a9b..6d23cacbf776 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -565,6 +565,8 @@ int ovl_update_time(struct inode *inode, int flags) }; if (upperpath.dentry) { + if (flags & S_NOWAIT) + return -EAGAIN; touch_atime(&upperpath); inode_set_atime_to_ts(inode, inode_get_atime(d_inode(upperpath.dentry))); diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c index fe236886484c..b74dd4d21330 100644 --- a/fs/ubifs/file.c +++ b/fs/ubifs/file.c @@ -1382,6 +1382,9 @@ int ubifs_update_time(struct inode *inode, int flags) if (!IS_ENABLED(CONFIG_UBIFS_ATIME_SUPPORT)) return generic_update_time(inode, flags); + if (flags & S_NOWAIT) + return -EAGAIN; + err = ubifs_budget_space(c, &req); if (err) return err; diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index 9dedb54e3cb0..626a541b247b 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -1195,6 +1195,9 @@ xfs_vn_update_time( trace_xfs_update_time(ip); + if (flags & S_NOWAIT) + return -EAGAIN; + if (inode->i_sb->s_flags & SB_LAZYTIME) { if (!((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false))) diff --git a/include/linux/fs.h b/include/linux/fs.h index d1d57149aa93..0ea175e19a8b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2239,10 +2239,23 @@ static inline void inode_dec_link_count(struct inode *inode) } enum file_time_flags { - S_ATIME = 1, - S_MTIME = 2, - S_CTIME = 4, - S_VERSION = 8, + /* update atime: */ + S_ATIME = 1U << 0, + + /* update mtime */ + S_MTIME = 1U << 1, + + /* update ctime */ + S_CTIME = 1U << 2, + + /* force update i_version even if no timestamp changes */ + S_VERSION = 1U << 3, + + /* only update timestamps or i_version if it doesn't require blocking */ + S_NOWAIT = 1U << 14, + + /* support S_NOWAIT for SB_LAZYTIME mounts in inode_update_timestamps */ + S_CAN_NOWAIT_LAZYTIME = 1U << 15, }; extern bool atime_needs_update(const struct path *, struct inode *); -- 2.47.3