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Tue, 6 Jan 2026 11:58:56 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id jzWMDgD5XGmibQAAD6G6ig (envelope-from ); Tue, 06 Jan 2026 11:58:56 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id EE62FA08E3; Tue, 6 Jan 2026 12:58:47 +0100 (CET) Date: Tue, 6 Jan 2026 12:58:47 +0100 From: Jan Kara To: Christoph Hellwig Cc: Christian Brauner , Al Viro , David Sterba , Jan Kara , Mike Marshall , Martin Brandenburg , Carlos Maiolino , Stefan Roesch , Jeff Layton , OGAWA Hirofumi , Trond Myklebust , Anna Schumaker , 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: Re: [PATCH 08/11] fs: add support for non-blocking timestamp updates Message-ID: References: <20260106075008.1610195-1-hch@lst.de> <20260106075008.1610195-9-hch@lst.de> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260106075008.1610195-9-hch@lst.de> X-Spamd-Result: default: False [-3.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_RHS_NOT_FQDN(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-0.991]; MIME_GOOD(-0.10)[text/plain]; MISSING_XM_UA(0.00)[]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[23]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; RCVD_TLS_LAST(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:email,imap1.dmz-prg2.suse.org:helo,lst.de:email,suse.cz:email] X-Spam-Level: X-Spam-Flag: NO X-Spam-Score: -3.80 On Tue 06-01-26 08:50:02, Christoph Hellwig wrote: > 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. > > Pass IOCB_NOWAIT to ->update_time and return -EAGAIN if it could block. > > Signed-off-by: Christoph Hellwig Much nicer now! Thanks for the refactoring. Feel free to add: Reviewed-by: Jan Kara Honza > --- > fs/btrfs/inode.c | 2 ++ > fs/gfs2/inode.c | 3 +++ > fs/inode.c | 45 +++++++++++++++++++++++++++++++++----------- > fs/orangefs/inode.c | 3 +++ > fs/overlayfs/inode.c | 2 ++ > fs/ubifs/file.c | 3 +++ > fs/xfs/xfs_iops.c | 3 +++ > 7 files changed, 50 insertions(+), 11 deletions(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 23fc38de9be5..241727459c0a 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -6362,6 +6362,8 @@ static int btrfs_update_time(struct inode *inode, enum fs_update_time type, > > if (btrfs_root_readonly(root)) > return -EROFS; > + if (flags & IOCB_NOWAIT) > + return -EAGAIN; > > dirty = inode_update_time(inode, type, flags); > if (dirty <= 0) > diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c > index 4ef39ff6889d..c02ebf0ca625 100644 > --- a/fs/gfs2/inode.c > +++ b/fs/gfs2/inode.c > @@ -2250,6 +2250,9 @@ static int gfs2_update_time(struct inode *inode, enum fs_update_time type, > struct gfs2_holder *gh; > int error; > > + if (flags & IOCB_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 c08682524a8d..01e4f6b9b46e 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -2090,7 +2090,7 @@ static int inode_update_atime(struct inode *inode) > return inode_time_dirty_flag(inode); > } > > -static int inode_update_cmtime(struct inode *inode) > +static int inode_update_cmtime(struct inode *inode, unsigned int flags) > { > struct timespec64 now = inode_set_ctime_current(inode); > struct timespec64 ctime = inode_get_ctime(inode); > @@ -2101,12 +2101,27 @@ static int inode_update_cmtime(struct inode *inode) > mtime_changed = !timespec64_equal(&now, &mtime); > if (mtime_changed || !timespec64_equal(&now, &ctime)) > dirty = inode_time_dirty_flag(inode); > - if (mtime_changed) > - inode_set_mtime_to_ts(inode, now); > > - if (IS_I_VERSION(inode) && inode_maybe_inc_iversion(inode, !!dirty)) > - dirty |= I_DIRTY_SYNC; > + /* > + * 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, the update of i_version can still block. > + * Error out if we'd actually have to update i_version or don't support > + * lazytime. > + */ > + if (IS_I_VERSION(inode)) { > + if (flags & IOCB_NOWAIT) { > + if (!(inode->i_sb->s_flags & SB_LAZYTIME) || > + inode_iversion_need_inc(inode)) > + return -EAGAIN; > + } else { > + if (inode_maybe_inc_iversion(inode, !!dirty)) > + dirty |= I_DIRTY_SYNC; > + } > + } > > + if (mtime_changed) > + inode_set_mtime_to_ts(inode, now); > return dirty; > } > > @@ -2131,7 +2146,7 @@ int inode_update_time(struct inode *inode, enum fs_update_time type, > case FS_UPD_ATIME: > return inode_update_atime(inode); > case FS_UPD_CMTIME: > - return inode_update_cmtime(inode); > + return inode_update_cmtime(inode, flags); > default: > WARN_ON_ONCE(1); > return -EIO; > @@ -2152,6 +2167,16 @@ int generic_update_time(struct inode *inode, enum fs_update_time type, > { > int dirty; > > + /* > + * ->dirty_inode is what could make generic timestamp updates block. > + * Don't support non-blocking timestamp updates here if it is set. > + * File systems that implement ->dirty_inode but want to support > + * non-blocking timestamp updates should call inode_update_time > + * directly. > + */ > + if ((flags & IOCB_NOWAIT) && inode->i_sb->s_op->dirty_inode) > + return -EAGAIN; > + > dirty = inode_update_time(inode, type, flags); > if (dirty <= 0) > return dirty; > @@ -2380,15 +2405,13 @@ static int file_update_time_flags(struct file *file, unsigned int flags) > if (!need_update) > return 0; > > - if (flags & IOCB_NOWAIT) > - return -EAGAIN; > - > + flags &= IOCB_NOWAIT; > if (mnt_get_write_access_file(file)) > return 0; > if (inode->i_op->update_time) > - ret = inode->i_op->update_time(inode, FS_UPD_CMTIME, 0); > + ret = inode->i_op->update_time(inode, FS_UPD_CMTIME, flags); > else > - ret = generic_update_time(inode, FS_UPD_CMTIME, 0); > + ret = generic_update_time(inode, FS_UPD_CMTIME, flags); > mnt_put_write_access_file(file); > return ret; > } > diff --git a/fs/orangefs/inode.c b/fs/orangefs/inode.c > index eab16afb5b8a..f420f48fc069 100644 > --- a/fs/orangefs/inode.c > +++ b/fs/orangefs/inode.c > @@ -878,6 +878,9 @@ int orangefs_update_time(struct inode *inode, enum fs_update_time type, > struct iattr iattr = { }; > int dirty; > > + if (flags & IOCB_NOWAIT) > + return -EAGAIN; > + > switch (type) { > case FS_UPD_ATIME: > iattr.ia_valid = ATTR_ATIME; > diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c > index c0ce3519e4af..00c69707bda9 100644 > --- a/fs/overlayfs/inode.c > +++ b/fs/overlayfs/inode.c > @@ -566,6 +566,8 @@ int ovl_update_time(struct inode *inode, enum fs_update_time type, > }; > > if (upperpath.dentry) { > + if (flags & IOCB_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 0cc44ad142de..3dc3ca1cd803 100644 > --- a/fs/ubifs/file.c > +++ b/fs/ubifs/file.c > @@ -1377,6 +1377,9 @@ int ubifs_update_time(struct inode *inode, enum fs_update_time type, > if (!IS_ENABLED(CONFIG_UBIFS_ATIME_SUPPORT)) > return generic_update_time(inode, type, flags); > > + if (flags & IOCB_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 d9eae1af14a8..aef5b05c1b76 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 & IOCB_NOWAIT) > + return -EAGAIN; > + > if (inode->i_sb->s_flags & SB_LAZYTIME) { > if (type == FS_UPD_ATIME || > !inode_maybe_inc_iversion(inode, false)) > -- > 2.47.3 > -- Jan Kara SUSE Labs, CR