Re: [PATCH 06/10] xfs_repair: clear the needsrepair flag

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

On Tue, Feb 09, 2021 at 12:20:29PM -0500, Brian Foster wrote:
> On Mon, Feb 08, 2021 at 08:10:38PM -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>
> > ---
> >  include/xfs_mount.h |    1 +
> >  libxfs/init.c       |   25 +++++++++++++------------
> >  repair/agheader.c   |   21 +++++++++++++++++++++
> >  repair/xfs_repair.c |   45 +++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 80 insertions(+), 12 deletions(-)
> > 
> > 
> ...
> > diff --git a/libxfs/init.c b/libxfs/init.c
> > index 9fe13b8d..98057b78 100644
> > --- a/libxfs/init.c
> > +++ b/libxfs/init.c
> > @@ -867,25 +867,17 @@ _("%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.
> > + * Persist all disk write caches and report on writes that didn't make it to
> > + * stable storage.  Callers should flush (or purge) the libxfs buffer caches
> > + * before calling this function.
> >   */
> > -static int
> > +int
> >  libxfs_flush_mount(
> >  	struct xfs_mount	*mp)
> >  {
> >  	int			error = 0;
> >  	int			err2;
> >  
> > -	/*
> > -	 * Purge the buffer cache to write all dirty buffers to disk and free
> > -	 * all incore buffers.  Buffers that fail write verification will cause
> > -	 * the CORRUPT_WRITE flag to be set in the buftarg.  Buffers that
> > -	 * cannot be written will cause the LOST_WRITE flag to be set in the
> > -	 * buftarg.
> > -	 */
> > -	libxfs_bcache_purge();
> > -
> 
> FWIW, my comment on the previous version was that I think it's
> reasonable to call libxfs_bcache_flush() here instead of the purge so
> callers don't necessarily have to do anything special. The one caller
> that does the purge is free to do so before calling
> libxfs_flush_mount(), as that essentially supercedes the flush that
> would otherwise occur here. Either way, the patch looks fine to me:

Ah, yeah.  That's a pretty simple change to make.  Thanks for the
review.

--D

> Reviewed-by: Brian Foster <bfoster@redhat.com>
> 
> >  	/* Flush all kernel and disk write caches, and report failures. */
> >  	if (mp->m_ddev_targp) {
> >  		err2 = libxfs_flush_buftarg(mp->m_ddev_targp, _("data device"));
> > @@ -923,6 +915,15 @@ libxfs_umount(
> >  
> >  	libxfs_rtmount_destroy(mp);
> >  
> > +	/*
> > +	 * Purge the buffer cache to write all dirty buffers to disk and free
> > +	 * all incore buffers.  Buffers that fail write verification will cause
> > +	 * the CORRUPT_WRITE flag to be set in the buftarg.  Buffers that
> > +	 * cannot be written will cause the LOST_WRITE flag to be set in the
> > +	 * buftarg.  Once that's done, instruct the disks to persist their
> > +	 * write caches.
> > +	 */
> > +	libxfs_bcache_purge();
> >  	error = libxfs_flush_mount(mp);
> >  
> >  	for (agno = 0; agno < mp->m_maxagi; agno++) {
> > diff --git a/repair/agheader.c b/repair/agheader.c
> > index 8bb99489..2af24106 100644
> > --- a/repair/agheader.c
> > +++ b/repair/agheader.c
> > @@ -452,6 +452,27 @@ secondary_sb_whack(
> >  			rval |= XR_AG_SB_SEC;
> >  	}
> >  
> > +	if (xfs_sb_version_needsrepair(sb)) {
> > +		if (i == 0) {
> > +			if (!no_modify)
> > +				do_warn(
> > +	_("clearing needsrepair flag and regenerating metadata\n"));
> > +			else
> > +				do_warn(
> > +	_("would clear needsrepair flag and regenerate metadata\n"));
> > +		} else {
> > +			/*
> > +			 * Quietly clear needsrepair on the secondary supers as
> > +			 * part of ensuring them.  If needsrepair is set on the
> > +			 * primary, it will be cleared at the end of repair
> > +			 * once we've flushed all other dirty blocks to disk.
> > +			 */
> > +			sb->sb_features_incompat &=
> > +					~XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR;
> > +			rval |= XR_AG_SB_SEC;
> > +		}
> > +	}
> > +
> >  	return(rval);
> >  }
> >  
> > diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c
> > index 32755821..f607afcb 100644
> > --- a/repair/xfs_repair.c
> > +++ b/repair/xfs_repair.c
> > @@ -712,6 +712,48 @@ 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.
> > +	 */
> > +	libxfs_bcache_flush();
> > +	error = -libxfs_flush_mount(mp);
> > +	if (error) {
> > +		do_warn(
> > +	_("Cannot clear needsrepair due to flush failure, err=%d.\n"),
> > +			error);
> > +		return;
> > +	}
> > +
> > +	/* Clear needsrepair from the superblock. */
> > +	bp = libxfs_getsb(mp);
> > +	if (!bp || bp->b_error) {
> > +		do_warn(
> > +	_("Cannot clear needsrepair from primary super, err=%d.\n"),
> > +			bp ? bp->b_error : ENOMEM);
> > +	} else {
> > +		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);
> > +	}
> > +	if (bp)
> > +		libxfs_buf_relse(bp);
> > +}
> > +
> >  int
> >  main(int argc, char **argv)
> >  {
> > @@ -1131,6 +1173,9 @@ _("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)
> > 
>