diff mbox series

[3/3] xfs: respect the stable writes flag on the RT device

Message ID 20231024064416.897956-4-hch@lst.de (mailing list archive)
State New, archived
Headers show
Series [1/3] filemap: add a per-mapping stable writes flag | expand

Commit Message

Christoph Hellwig Oct. 24, 2023, 6:44 a.m. UTC
Update the per-folio stable writes flag dependening on which device an
inode resides on.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_inode.h | 8 ++++++++
 fs/xfs/xfs_ioctl.c | 9 +++++++++
 fs/xfs/xfs_iops.c  | 7 +++++++
 3 files changed, 24 insertions(+)

Comments

Darrick J. Wong Oct. 24, 2023, 3:09 p.m. UTC | #1
On Tue, Oct 24, 2023 at 08:44:16AM +0200, Christoph Hellwig wrote:
> Update the per-folio stable writes flag dependening on which device an
> inode resides on.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/xfs_inode.h | 8 ++++++++
>  fs/xfs/xfs_ioctl.c | 9 +++++++++
>  fs/xfs/xfs_iops.c  | 7 +++++++
>  3 files changed, 24 insertions(+)
> 
> diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> index 0c5bdb91152e1c..682959c8f78cb0 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -561,6 +561,14 @@ extern void xfs_setup_inode(struct xfs_inode *ip);
>  extern void xfs_setup_iops(struct xfs_inode *ip);
>  extern void xfs_diflags_to_iflags(struct xfs_inode *ip, bool init);
>  
> +static inline void xfs_update_stable_writes(struct xfs_inode *ip)
> +{
> +	if (bdev_stable_writes(xfs_inode_buftarg(ip)->bt_bdev))
> +		mapping_set_stable_writes(VFS_I(ip)->i_mapping);
> +	else
> +		mapping_clear_stable_writes(VFS_I(ip)->i_mapping);
> +}
> +
>  /*
>   * When setting up a newly allocated inode, we need to call
>   * xfs_finish_inode_setup() once the inode is fully instantiated at
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 55bb01173cde8c..67bf613b3c86bc 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -1147,6 +1147,15 @@ xfs_ioctl_setattr_xflags(
>  	ip->i_diflags2 = i_flags2;
>  
>  	xfs_diflags_to_iflags(ip, false);
> +
> +	/*
> +	 * Make the stable writes flag match that of the device the inode
> +	 * resides on when flipping the RT flag.
> +	 */
> +	if (S_ISREG(VFS_I(ip)->i_mode) &&
> +	    XFS_IS_REALTIME_INODE(ip) != (fa->fsx_xflags & FS_XFLAG_REALTIME))
> +		xfs_update_stable_writes(ip);

Hmm.  Won't the masking operation here result in the if test comparing 0
or FS_XFLAG_REALTIME to 0 or 1?

Oh.  FS_XFLAG_REALTIME == 1, so that's not an issue in this one case.
That's a bit subtle though, I'd have preferred

	    XFS_IS_REALTIME_INODE(ip) != !!(fa->fsx_xflags & FS_XFLAG_REALTIME))

to make it more obvious that the if test isn't comparing apples to
oranges.

> +
>  	xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
>  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
>  	XFS_STATS_INC(mp, xs_ig_attrchg);
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 2b3b05c28e9e48..b8ec045708c318 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -1298,6 +1298,13 @@ xfs_setup_inode(
>  	gfp_mask = mapping_gfp_mask(inode->i_mapping);
>  	mapping_set_gfp_mask(inode->i_mapping, (gfp_mask & ~(__GFP_FS)));
>  
> +	/*
> +	 * For real-time inodes update the stable write flags to that of the RT
> +	 * device instead of the data device.
> +	 */
> +	if (S_ISREG(inode->i_mode) && XFS_IS_REALTIME_INODE(ip))
> +		xfs_update_stable_writes(ip);

I wonder if xfs_update_stable_writes should become an empty function for
the CONFIG_XFS_RT=n case, to avoid the atomic flags update?

(The extra code is probably not worth the microoptimization.)

With the !! nit addressed,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> +
>  	/*
>  	 * If there is no attribute fork no ACL can exist on this inode,
>  	 * and it can't have any file capabilities attached to it either.
> -- 
> 2.39.2
>
Matthew Wilcox Oct. 24, 2023, 3:14 p.m. UTC | #2
On Tue, Oct 24, 2023 at 08:09:04AM -0700, Darrick J. Wong wrote:
> > +	if (S_ISREG(VFS_I(ip)->i_mode) &&
> > +	    XFS_IS_REALTIME_INODE(ip) != (fa->fsx_xflags & FS_XFLAG_REALTIME))
> > +		xfs_update_stable_writes(ip);
> 
> Hmm.  Won't the masking operation here result in the if test comparing 0
> or FS_XFLAG_REALTIME to 0 or 1?
> 
> Oh.  FS_XFLAG_REALTIME == 1, so that's not an issue in this one case.
> That's a bit subtle though, I'd have preferred
> 
> 	    XFS_IS_REALTIME_INODE(ip) != !!(fa->fsx_xflags & FS_XFLAG_REALTIME))
> 
> to make it more obvious that the if test isn't comparing apples to
> oranges.

!= !! might be going a bit far.  Would you settle for

XFS_IS_REALTIME_INODE(ip) == !(fa->fsx_xflags & FS_XFLAG_REALTIME)

?  Although none of these read particularly nicely.  Maybe

	XFS_IS_REALTIME_INODE(ip) != ((fa->fsx_xflags & FS_XFLAG_REALTIME) == 0))

Perhaps we need a bool helper for (fa->fsx_xflags & FS_XFLAG_REALTIME)
Christoph Hellwig Oct. 24, 2023, 4:16 p.m. UTC | #3
On Tue, Oct 24, 2023 at 08:09:04AM -0700, Darrick J. Wong wrote:
> > +	/*
> > +	 * Make the stable writes flag match that of the device the inode
> > +	 * resides on when flipping the RT flag.
> > +	 */
> > +	if (S_ISREG(VFS_I(ip)->i_mode) &&
> > +	    XFS_IS_REALTIME_INODE(ip) != (fa->fsx_xflags & FS_XFLAG_REALTIME))
> > +		xfs_update_stable_writes(ip);
> 
> Hmm.  Won't the masking operation here result in the if test comparing 0
> or FS_XFLAG_REALTIME to 0 or 1?
> 
> Oh.  FS_XFLAG_REALTIME == 1, so that's not an issue in this one case.
> That's a bit subtle though, I'd have preferred
> 
> 	    XFS_IS_REALTIME_INODE(ip) != !!(fa->fsx_xflags & FS_XFLAG_REALTIME))
> 
> to make it more obvious that the if test isn't comparing apples to
> oranges.

This is all copy and pasted from a check a few lines above :)

I guess I could clean it up as well or even add a rt_flag_changed local
variable instead of duplicating the check.

> > +	/*
> > +	 * For real-time inodes update the stable write flags to that of the RT
> > +	 * device instead of the data device.
> > +	 */
> > +	if (S_ISREG(inode->i_mode) && XFS_IS_REALTIME_INODE(ip))
> > +		xfs_update_stable_writes(ip);
> 
> I wonder if xfs_update_stable_writes should become an empty function for
> the CONFIG_XFS_RT=n case, to avoid the atomic flags update?
> 
> (The extra code is probably not worth the microoptimization.)

The compiler already eliminates the code because XFS_IS_REALTIME_INODE(ip)
has a stub for CONFIG_XFS_RT=n that always returns 0.
diff mbox series

Patch

diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 0c5bdb91152e1c..682959c8f78cb0 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -561,6 +561,14 @@  extern void xfs_setup_inode(struct xfs_inode *ip);
 extern void xfs_setup_iops(struct xfs_inode *ip);
 extern void xfs_diflags_to_iflags(struct xfs_inode *ip, bool init);
 
+static inline void xfs_update_stable_writes(struct xfs_inode *ip)
+{
+	if (bdev_stable_writes(xfs_inode_buftarg(ip)->bt_bdev))
+		mapping_set_stable_writes(VFS_I(ip)->i_mapping);
+	else
+		mapping_clear_stable_writes(VFS_I(ip)->i_mapping);
+}
+
 /*
  * When setting up a newly allocated inode, we need to call
  * xfs_finish_inode_setup() once the inode is fully instantiated at
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 55bb01173cde8c..67bf613b3c86bc 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1147,6 +1147,15 @@  xfs_ioctl_setattr_xflags(
 	ip->i_diflags2 = i_flags2;
 
 	xfs_diflags_to_iflags(ip, false);
+
+	/*
+	 * Make the stable writes flag match that of the device the inode
+	 * resides on when flipping the RT flag.
+	 */
+	if (S_ISREG(VFS_I(ip)->i_mode) &&
+	    XFS_IS_REALTIME_INODE(ip) != (fa->fsx_xflags & FS_XFLAG_REALTIME))
+		xfs_update_stable_writes(ip);
+
 	xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 	XFS_STATS_INC(mp, xs_ig_attrchg);
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 2b3b05c28e9e48..b8ec045708c318 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1298,6 +1298,13 @@  xfs_setup_inode(
 	gfp_mask = mapping_gfp_mask(inode->i_mapping);
 	mapping_set_gfp_mask(inode->i_mapping, (gfp_mask & ~(__GFP_FS)));
 
+	/*
+	 * For real-time inodes update the stable write flags to that of the RT
+	 * device instead of the data device.
+	 */
+	if (S_ISREG(inode->i_mode) && XFS_IS_REALTIME_INODE(ip))
+		xfs_update_stable_writes(ip);
+
 	/*
 	 * If there is no attribute fork no ACL can exist on this inode,
 	 * and it can't have any file capabilities attached to it either.