Re: [PATCH 5/5] xfs_repair: clear the needsrepair flag

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Feb 04, 2021 at 12:55:12PM -0500, Brian Foster wrote:
> On Wed, Feb 03, 2021 at 11:43:40AM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > Clear the needsrepair flag, since it's used to prevent mounting of an
> > inconsistent filesystem.  We only do this if we make it to the end of
> > repair with a non-zero error code, and all the rebuilt indices and
> > corrected metadata are persisted correctly.
> > 
> > Note that we cannot combine clearing needsrepair with clearing the quota
> > checked flags because we need to clear the quota flags even if
> > reformatting the log fails, whereas we can't clear needsrepair if the
> > log reformat fails.
> > 
> > Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> > ---
> 
> Looks sane, just some nits...
> 
> >  include/xfs_mount.h |    1 +
> >  libxfs/init.c       |   12 ++++++++----
> >  repair/agheader.c   |   21 +++++++++++++++++++++
> >  repair/xfs_repair.c |   49 +++++++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 79 insertions(+), 4 deletions(-)
> > 
> > 
> ...
> > diff --git a/libxfs/init.c b/libxfs/init.c
> > index 9fe13b8d..99b1f72a 100644
> > --- a/libxfs/init.c
> > +++ b/libxfs/init.c
> > @@ -870,9 +870,10 @@ _("%s: Flushing the %s failed, err=%d!\n"),
> >   * Flush all dirty buffers to stable storage and report on writes that didn't
> >   * make it to stable storage.
> >   */
> > -static int
> > +int
> >  libxfs_flush_mount(
> > -	struct xfs_mount	*mp)
> > +	struct xfs_mount	*mp,
> > +	bool			purge)
> >  {
> >  	int			error = 0;
> >  	int			err2;
> > @@ -884,7 +885,10 @@ libxfs_flush_mount(
> >  	 * cannot be written will cause the LOST_WRITE flag to be set in the
> >  	 * buftarg.
> >  	 */
> > -	libxfs_bcache_purge();
> > +	if (purge)
> > +		libxfs_bcache_purge();
> > +	else
> > +		libxfs_bcache_flush();
> 
> Instead of the parameter, could we just lift the purge into the call
> that requires it and let libxfs_flush_mount() just do flushes? I'm
> assuming the bcache would be empty in the umount case so the extra flush
> should pretty much be a no-op.

<nod> Will do.

> 
> >  
> >  	/* Flush all kernel and disk write caches, and report failures. */
> >  	if (mp->m_ddev_targp) {
> > @@ -923,7 +927,7 @@ libxfs_umount(
> >  
> >  	libxfs_rtmount_destroy(mp);
> >  
> > -	error = libxfs_flush_mount(mp);
> > +	error = libxfs_flush_mount(mp, true);
> >  
> >  	for (agno = 0; agno < mp->m_maxagi; agno++) {
> >  		pag = radix_tree_delete(&mp->m_perag_tree, agno);
> ...
> > diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c
> > index 9409f0d8..4ca4fe5a 100644
> > --- a/repair/xfs_repair.c
> > +++ b/repair/xfs_repair.c
> > @@ -712,6 +712,52 @@ check_fs_vs_host_sectsize(
> >  	}
> >  }
> >  
> > +/* Clear needsrepair after a successful repair run. */
> > +void
> > +clear_needsrepair(
> > +	struct xfs_mount	*mp)
> > +{
> > +	struct xfs_buf		*bp;
> > +	int			error;
> > +
> > +	/*
> > +	 * If we're going to clear NEEDSREPAIR, we need to make absolutely sure
> > +	 * that everything is ok with the ondisk filesystem.  At this point
> > +	 * we've flushed the filesystem metadata out of the buffer cache and
> > +	 * possibly rewrote the log, but we haven't forced the disks to persist
> > +	 * the writes to stable storage.  Do that now, and if anything goes
> > +	 * wrong, leave NEEDSREPAIR in place.  Don't purge the buffer cache
> > +	 * here since we're not done yet.
> > +	 */
> > +	error = -libxfs_flush_mount(mp, false);
> > +	if (error) {
> > +		do_warn(
> > +	_("Cannot clear needsrepair from primary super due to metadata checkpoint failure, err=%d.\n"),
> > +			error);
> 
> Not sure what metadata checkpoint failure means.. maybe just say that a
> flush failed?

Ok.

> > +		return;
> > +	}
> > +
> > +	/* Clear needsrepair from the superblock. */
> > +	bp = libxfs_getsb(mp);
> > +	if (!bp) {
> > +		do_warn(
> > +	_("Cannot clear needsrepair from primary super, out of memory.\n"));
> > +		return;
> > +	}
> > +	if (bp->b_error) {
> > +		do_warn(
> > +	_("Cannot clear needsrepair from primary super, IO err=%d.\n"),
> > +			bp->b_error);
> > +	} else {
> 
> Maybe try to condense this a bit to something like the following to
> reduce the number of branches and strings to translate and whatnot:
> 
> 	if (!bp || bp->b_error) {
> 		do_warn(
> 		"Failed to clear needsrepair from primary super, err=%d.\n",
> 			bp ? bp->b_error : -ENOMEM);
> 		goto out;
> 	}
> 
> 	...
> out:
> 	libxfs_buf_release(bp);

Ok.

> }
> 
> > +		mp->m_sb.sb_features_incompat &=
> > +				~XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR;
> > +		libxfs_sb_to_disk(bp->b_addr, &mp->m_sb);
> > +		libxfs_buf_mark_dirty(bp);
> > +	}
> > +	libxfs_buf_relse(bp);
> > +	return;
> 
> No need for the return statement here.

Fixed, thanks for the nits. :)

--D

> Brian
> 
> > +}
> > +
> >  int
> >  main(int argc, char **argv)
> >  {
> > @@ -1132,6 +1178,9 @@ _("Note - stripe unit (%d) and width (%d) were copied from a backup superblock.\
> >  	libxfs_bcache_flush();
> >  	format_log_max_lsn(mp);
> >  
> > +	if (xfs_sb_version_needsrepair(&mp->m_sb))
> > +		clear_needsrepair(mp);
> > +
> >  	/* Report failure if anything failed to get written to our fs. */
> >  	error = -libxfs_umount(mp);
> >  	if (error)
> > 
>