[2/2] writeback, xfs: call dirty_inode() with I_DIRTY_TIME_EXPIRED when appropriate

Use the flag I_DIRTY_TIME_EXPIRED passed to dirty_inode() to signal to
the file system that it is time to flush the inode's timestamps to
stable storage.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/fs-writeback.c  | 2 +-
 fs/xfs/xfs_super.c | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

Christoph, Dave --- does this give you the notification that you were
looking such that XFS could get the notification desired that it was
the timestamps need to be written back?

    	       	       	  	  - Ted

On Thu, Mar 19, 2020 at 10:52:55PM -0400, Theodore Ts'o wrote:
> Use the flag I_DIRTY_TIME_EXPIRED passed to dirty_inode() to signal to
> the file system that it is time to flush the inode's timestamps to
> stable storage.
> 
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> ---
>  fs/fs-writeback.c  | 2 +-
>  fs/xfs/xfs_super.c | 3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 867454997c9d..32101349ba97 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -1506,7 +1506,7 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
>  
>  	/* This was a lazytime expiration; we need to tell the file system */
>  	if (dirty & I_DIRTY_TIME_EXPIRED && inode->i_sb->s_op->dirty_inode)
> -		inode->i_sb->s_op->dirty_inode(inode, I_DIRTY_SYNC);
> +		inode->i_sb->s_op->dirty_inode(inode, I_DIRTY_TIME_EXPIRED);
>  	/* Don't write the inode if only I_DIRTY_PAGES was set */
>  	if (dirty & ~I_DIRTY_PAGES) {
>  		int err = write_inode(inode, wbc);
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 2094386af8ac..f27b9b205f81 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -622,7 +622,8 @@ xfs_fs_dirty_inode(
>  
>  	if (!(inode->i_sb->s_flags & SB_LAZYTIME))
>  		return;
> -	if (flag != I_DIRTY_SYNC || !(inode->i_state & I_DIRTY_TIME))
> +	if ((flag != I_DIRTY_SYNC && flag != I_DIRTY_TIME_EXPIRED) ||
> +	    !(inode->i_state & I_DIRTY_TIME))
>  		return;
>  
>  	if (xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp))
> -- 
> 2.24.1
>

On Mon, Mar 23, 2020 at 01:58:38PM -0400, Theodore Y. Ts'o wrote:
> Christoph, Dave --- does this give you the notification that you were
> looking such that XFS could get the notification desired that it was
> the timestamps need to be written back?

I need to look at it in more detail as it seems convoluted.  Also the
order seems like you regress XFS in patch 1 and then fix it in patch 2?

On Tue, Mar 24, 2020 at 01:37:59AM -0700, Christoph Hellwig wrote:
> On Mon, Mar 23, 2020 at 01:58:38PM -0400, Theodore Y. Ts'o wrote:
> > Christoph, Dave --- does this give you the notification that you were
> > looking such that XFS could get the notification desired that it was
> > the timestamps need to be written back?
> 
> I need to look at it in more detail as it seems convoluted.  Also the
> order seems like you regress XFS in patch 1 and then fix it in patch 2?

In patch one we send I_DIRTY_SYNC as we had been doing as before.  So
I don't believe that patch #1 would regress XFS; can you confirm?

My thinking was to move ahead with patch 1 so that it fixed the bug
which Eric Biffers had reported for f2fs, but only to move forward
with patch #2 if it would be useful for XFS.

Cheers,

     	      	    	     	    - Ted