Re: [PATCH 07/12] xfs: flush eof/cowblocks if we can't reserve quota for file blocks

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

On Tue, Feb 02, 2021 at 10:38:59AM -0500, Brian Foster wrote:
> On Sun, Jan 31, 2021 at 06:06:06PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > If a fs modification (data write, reflink, xattr set, fallocate, etc.)
> > is unable to reserve enough quota to handle the modification, try
> > clearing whatever space the filesystem might have been hanging onto in
> > the hopes of speeding up the filesystem.  The flushing behavior will
> > become particularly important when we add deferred inode inactivation
> > because that will increase the amount of space that isn't actively tied
> > to user data.
> > 
> > Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> > ---
> 
> (FWIW, I'm reviewing the patches from your reclaim-space-harder-5.12
> branch as of this morning, which look like they have some deltas from
> the posted versions based on Christoph's feedback.)

Yes, it does. :(

I pushed the branches and had sent the first of the two patchsets
last night, and then the power went out so I gave up and went to bed.

But thanks for the review. :)

--D

> Reviewed-by: Brian Foster <bfoster@redhat.com>
> 
> >  fs/xfs/xfs_reflink.c |    5 +++++
> >  fs/xfs/xfs_trans.c   |   10 ++++++++++
> >  2 files changed, 15 insertions(+)
> > 
> > 
> > diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> > index 086866f6e71f..725c7d8e4438 100644
> > --- a/fs/xfs/xfs_reflink.c
> > +++ b/fs/xfs/xfs_reflink.c
> > @@ -1092,6 +1092,11 @@ xfs_reflink_remap_extent(
> >  	 * count.  This is suboptimal, but the VFS flushed the dest range
> >  	 * before we started.  That should have removed all the delalloc
> >  	 * reservations, but we code defensively.
> > +	 *
> > +	 * xfs_trans_alloc_inode above already tried to grab an even larger
> > +	 * quota reservation, and kicked off a blockgc scan if it couldn't.
> > +	 * If we can't get a potentially smaller quota reservation now, we're
> > +	 * done.
> >  	 */
> >  	if (!quota_reserved && !smap_real && dmap_written) {
> >  		error = xfs_trans_reserve_quota_nblks(tp, ip,
> > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
> > index 466e1c86767f..f62c1c5f210f 100644
> > --- a/fs/xfs/xfs_trans.c
> > +++ b/fs/xfs/xfs_trans.c
> > @@ -23,6 +23,7 @@
> >  #include "xfs_inode.h"
> >  #include "xfs_dquot_item.h"
> >  #include "xfs_dquot.h"
> > +#include "xfs_icache.h"
> >  
> >  kmem_zone_t	*xfs_trans_zone;
> >  
> > @@ -1046,8 +1047,10 @@ xfs_trans_alloc_inode(
> >  {
> >  	struct xfs_trans	*tp;
> >  	struct xfs_mount	*mp = ip->i_mount;
> > +	bool			retried = false;
> >  	int			error;
> >  
> > +retry:
> >  	error = xfs_trans_alloc(mp, resv, dblocks,
> >  			rblocks / mp->m_sb.sb_rextsize,
> >  			force ? XFS_TRANS_RESERVE : 0, &tp);
> > @@ -1065,6 +1068,13 @@ xfs_trans_alloc_inode(
> >  	}
> >  
> >  	error = xfs_trans_reserve_quota_nblks(tp, ip, dblocks, rblocks, force);
> > +	if (!retried && (error == -EDQUOT || error == -ENOSPC)) {
> > +		xfs_trans_cancel(tp);
> > +		xfs_iunlock(ip, XFS_ILOCK_EXCL);
> > +		xfs_blockgc_free_quota(ip, 0);
> > +		retried = true;
> > +		goto retry;
> > +	}
> >  	if (error)
> >  		goto out_cancel;
> >  
> > 
>