diff mbox series

[v3,4/4] xfs: support shrinking unused space in the last AG

Message ID 20210108190919.623672-5-hsiangkao@redhat.com (mailing list archive)
State Superseded
Headers show
Series xfs: support shrinking free space in the last AG | expand

Commit Message

Gao Xiang Jan. 8, 2021, 7:09 p.m. UTC 
As the first step of shrinking, this attempts to enable shrinking
unused space in the last allocation group by fixing up freespace
btree, agi, agf and adjusting super block and introduce a helper
xfs_ag_shrink_space() to fixup the last AG.

This can be all done in one transaction for now, so I think no
additional protection is needed.

Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
---
 fs/xfs/libxfs/xfs_ag.c | 72 ++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_ag.h |  2 ++
 fs/xfs/xfs_fsops.c     | 69 ++++++++++++++++++++++++++++++----------
 fs/xfs/xfs_trans.c     |  1 -
 4 files changed, 126 insertions(+), 18 deletions(-)

Comments

Darrick J. Wong Jan. 8, 2021, 9:19 p.m. UTC | #1 
On Sat, Jan 09, 2021 at 03:09:19AM +0800, Gao Xiang wrote:
> As the first step of shrinking, this attempts to enable shrinking
> unused space in the last allocation group by fixing up freespace
> btree, agi, agf and adjusting super block and introduce a helper
> xfs_ag_shrink_space() to fixup the last AG.
> 
> This can be all done in one transaction for now, so I think no
> additional protection is needed.
> 
> Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
> ---
>  fs/xfs/libxfs/xfs_ag.c | 72 ++++++++++++++++++++++++++++++++++++++++++
>  fs/xfs/libxfs/xfs_ag.h |  2 ++
>  fs/xfs/xfs_fsops.c     | 69 ++++++++++++++++++++++++++++++----------
>  fs/xfs/xfs_trans.c     |  1 -
>  4 files changed, 126 insertions(+), 18 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
> index 9331f3516afa..bec10c85e2a9 100644
> --- a/fs/xfs/libxfs/xfs_ag.c
> +++ b/fs/xfs/libxfs/xfs_ag.c
> @@ -485,6 +485,78 @@ xfs_ag_init_headers(
>  	return error;
>  }
>  
> +int
> +xfs_ag_shrink_space(
> +	struct xfs_mount	*mp,
> +	struct xfs_trans	*tp,
> +	struct aghdr_init_data	*id,
> +	xfs_extlen_t		len)
> +{
> +	struct xfs_buf		*agibp, *agfbp;
> +	struct xfs_agi		*agi;
> +	struct xfs_agf		*agf;
> +	int			error, err2;
> +	struct xfs_alloc_arg	args = {
> +		.tp	= tp,
> +		.mp	= mp,
> +		.type	= XFS_ALLOCTYPE_THIS_BNO,
> +		.minlen = len,
> +		.maxlen = len,
> +		.oinfo	= XFS_RMAP_OINFO_SKIP_UPDATE,
> +		.resv	= XFS_AG_RESV_NONE,
> +		.prod	= 1
> +	};
> +
> +	ASSERT(id->agno == mp->m_sb.sb_agcount - 1);
> +	error = xfs_ialloc_read_agi(mp, tp, id->agno, &agibp);
> +	if (error)
> +		return error;
> +
> +	agi = agibp->b_addr;
> +
> +	error = xfs_alloc_read_agf(mp, tp, id->agno, 0, &agfbp);
> +	if (error)
> +		return error;
> +
> +	args.fsbno = XFS_AGB_TO_FSB(mp, id->agno,
> +				    be32_to_cpu(agi->agi_length) - len);
> +
> +	/* remove the preallocations before allocation and re-establish then */
> +	error = xfs_ag_resv_free(agibp->b_pag);
> +	if (error)
> +		return error;
> +
> +	/* internal log shouldn't also show up in the free space btrees */
> +	error = xfs_alloc_vextent(&args);
> +	if (error)
> +		goto out;
> +
> +	if (args.agbno == NULLAGBLOCK) {
> +		error = -ENOSPC;
> +		goto out;
> +	}
> +
> +	/* Change the agi length */
> +	be32_add_cpu(&agi->agi_length, -len);
> +	xfs_ialloc_log_agi(tp, agibp, XFS_AGI_LENGTH);
> +
> +	/* Change agf length */
> +	agf = agfbp->b_addr;
> +	be32_add_cpu(&agf->agf_length, -len);
> +	ASSERT(agf->agf_length == agi->agi_length);
> +	xfs_alloc_log_agf(tp, agfbp, XFS_AGF_LENGTH);
> +
> +out:
> +	err2 = xfs_ag_resv_init(agibp->b_pag, tp);
> +	if (err2 && err2 != -ENOSPC) {
> +		xfs_warn(mp,
> +"Error %d reserving per-AG metadata reserve pool.", err2);
> +		xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
> +		return err2;
> +	}
> +	return error;
> +}
> +
>  /*
>   * Extent the AG indicated by the @id by the length passed in
>   */
> diff --git a/fs/xfs/libxfs/xfs_ag.h b/fs/xfs/libxfs/xfs_ag.h
> index 5166322807e7..f3b5bbfeadce 100644
> --- a/fs/xfs/libxfs/xfs_ag.h
> +++ b/fs/xfs/libxfs/xfs_ag.h
> @@ -24,6 +24,8 @@ struct aghdr_init_data {
>  };
>  
>  int xfs_ag_init_headers(struct xfs_mount *mp, struct aghdr_init_data *id);
> +int xfs_ag_shrink_space(struct xfs_mount *mp, struct xfs_trans *tp,
> +			struct aghdr_init_data *id, xfs_extlen_t len);
>  int xfs_ag_extend_space(struct xfs_mount *mp, struct xfs_trans *tp,
>  			struct aghdr_init_data *id, xfs_extlen_t len);
>  int xfs_ag_get_geometry(struct xfs_mount *mp, xfs_agnumber_t agno,
> diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
> index a792d1f0ac55..eea38395e804 100644
> --- a/fs/xfs/xfs_fsops.c
> +++ b/fs/xfs/xfs_fsops.c
> @@ -79,19 +79,22 @@ xfs_growfs_data_private(
>  	xfs_rfsblock_t		delta;
>  	xfs_agnumber_t		oagcount;
>  	struct xfs_trans	*tp;
> +	bool			extend;
>  	struct aghdr_init_data	id = {};
>  
>  	nb = in->newblocks;
> -	if (nb < mp->m_sb.sb_dblocks)
> -		return -EINVAL;
> -	if ((error = xfs_sb_validate_fsb_count(&mp->m_sb, nb)))
> +	error = xfs_sb_validate_fsb_count(&mp->m_sb, nb);
> +	if (error)
>  		return error;
> -	error = xfs_buf_read_uncached(mp->m_ddev_targp,
> +
> +	if (nb > mp->m_sb.sb_dblocks) {
> +		error = xfs_buf_read_uncached(mp->m_ddev_targp,
>  				XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
>  				XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
> -	if (error)
> -		return error;
> -	xfs_buf_relse(bp);
> +		if (error)
> +			return error;
> +		xfs_buf_relse(bp);
> +	}
>  
>  	delta = nb;	/* use delta as a temporary here */

Yikes, can this become a separate variable please?

>  	nb_mod = do_div(delta, mp->m_sb.sb_agblocks);
> @@ -99,10 +102,18 @@ xfs_growfs_data_private(
>  	if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) {
>  		nagcount--;
>  		nb = (xfs_rfsblock_t)nagcount * mp->m_sb.sb_agblocks;
> -		if (nb < mp->m_sb.sb_dblocks)
> +		if (nagcount < 2)
>  			return -EINVAL;
>  	}
> -	delta = nb - mp->m_sb.sb_dblocks;
> +
> +	if (nb > mp->m_sb.sb_dblocks) {
> +		delta = nb - mp->m_sb.sb_dblocks;
> +		extend = true;
> +	} else {
> +		delta = mp->m_sb.sb_dblocks - nb;
> +		extend = false;

/me wonders why delta isn't simply int64_t, and then you can do things
like:

if (delta > 0)
	growfs
else if (delta < 0)
	shrinkfs

?

> +	}
> +
>  	oagcount = mp->m_sb.sb_agcount;
>  
>  	/* allocate the new per-ag structures */
> @@ -110,22 +121,34 @@ xfs_growfs_data_private(
>  		error = xfs_initialize_perag(mp, nagcount, &nagimax);
>  		if (error)
>  			return error;
> +	} else if (nagcount != oagcount) {
> +		/* TODO: shrinking the entire AGs hasn't yet completed */
> +		return -EINVAL;
>  	}
>  
>  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata,
> -			XFS_GROWFS_SPACE_RES(mp), 0, XFS_TRANS_RESERVE, &tp);
> +			(extend ? XFS_GROWFS_SPACE_RES(mp) : delta), 0,
> +			XFS_TRANS_RESERVE, &tp);
>  	if (error)
>  		return error;
>  
> -	error = xfs_resizefs_init_new_ags(mp, &id, oagcount, nagcount, &delta);
> -	if (error)
> -		goto out_trans_cancel;
> -
> +	if (extend) {
> +		error = xfs_resizefs_init_new_ags(mp, &id, oagcount,
> +						  nagcount, &delta);
> +		if (error)
> +			goto out_trans_cancel;
> +	}
>  	xfs_trans_agblocks_delta(tp, id.nfree);
>  
> -	/* If there are new blocks in the old last AG, extend it. */
> +	/* If there are some blocks in the last AG, resize it. */
>  	if (delta) {
> -		error = xfs_ag_extend_space(mp, tp, &id, delta);
> +		if (extend) {
> +			error = xfs_ag_extend_space(mp, tp, &id, delta);
> +		} else {
> +			id.agno = nagcount - 1;
> +			error = xfs_ag_shrink_space(mp, tp, &id, delta);
> +		}
> +
>  		if (error)
>  			goto out_trans_cancel;
>  	}
> @@ -137,11 +160,19 @@ xfs_growfs_data_private(
>  	 */
>  	if (nagcount > oagcount)
>  		xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
> -	if (nb > mp->m_sb.sb_dblocks)
> +	if (nb != mp->m_sb.sb_dblocks)
>  		xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS,
>  				 nb - mp->m_sb.sb_dblocks);
>  	if (id.nfree)
>  		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, id.nfree);
> +
> +	/*
> +	 * update in-core counters (especially sb_fdblocks) now
> +	 * so xfs_validate_sb_write() can pass.
> +	 */
> +	if (xfs_sb_version_haslazysbcount(&mp->m_sb))
> +		xfs_log_sb(tp);
> +
>  	xfs_trans_set_sync(tp);
>  	error = xfs_trans_commit(tp);
>  	if (error)
> @@ -178,6 +209,10 @@ xfs_growfs_data_private(
>  	return error;
>  
>  out_trans_cancel:
> +	if (!extend && (tp->t_flags & XFS_TRANS_DIRTY)) {
> +		xfs_trans_commit(tp);
> +		return error;

When do we encounter the (!extend && DIRTY && cancelled) state?

--D

> +	}
>  	xfs_trans_cancel(tp);
>  	return error;
>  }
> diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
> index e72730f85af1..fd2cbf414b80 100644
> --- a/fs/xfs/xfs_trans.c
> +++ b/fs/xfs/xfs_trans.c
> @@ -419,7 +419,6 @@ xfs_trans_mod_sb(
>  		tp->t_res_frextents_delta += delta;
>  		break;
>  	case XFS_TRANS_SB_DBLOCKS:
> -		ASSERT(delta > 0);
>  		tp->t_dblocks_delta += delta;
>  		break;
>  	case XFS_TRANS_SB_AGCOUNT:
> -- 
> 2.27.0
>
Gao Xiang Jan. 9, 2021, 12:47 a.m. UTC | #2 
Hi Darrick,

On Fri, Jan 08, 2021 at 01:19:42PM -0800, Darrick J. Wong wrote:
> On Sat, Jan 09, 2021 at 03:09:19AM +0800, Gao Xiang wrote:

...

> >  	delta = nb;	/* use delta as a temporary here */
> 
> Yikes, can this become a separate variable please?

Ok.

> 
> >  	nb_mod = do_div(delta, mp->m_sb.sb_agblocks);
> > @@ -99,10 +102,18 @@ xfs_growfs_data_private(
> >  	if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) {
> >  		nagcount--;
> >  		nb = (xfs_rfsblock_t)nagcount * mp->m_sb.sb_agblocks;
> > -		if (nb < mp->m_sb.sb_dblocks)
> > +		if (nagcount < 2)
> >  			return -EINVAL;
> >  	}
> > -	delta = nb - mp->m_sb.sb_dblocks;
> > +
> > +	if (nb > mp->m_sb.sb_dblocks) {
> > +		delta = nb - mp->m_sb.sb_dblocks;
> > +		extend = true;
> > +	} else {
> > +		delta = mp->m_sb.sb_dblocks - nb;
> > +		extend = false;
> 
> /me wonders why delta isn't simply int64_t, and then you can do things
> like:
> 
> if (delta > 0)
> 	growfs
> else if (delta < 0)
> 	shrinkfs
> 
> ?

Yeah, delta changed into a signed variable in mycurrent experimental
shrinking entire AG hack as well. Will update this here in advance.

Thanks,
Gao Xiang
diff mbox series

Patch

diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index 9331f3516afa..bec10c85e2a9 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -485,6 +485,78 @@  xfs_ag_init_headers(
 	return error;
 }
 
+int
+xfs_ag_shrink_space(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	struct aghdr_init_data	*id,
+	xfs_extlen_t		len)
+{
+	struct xfs_buf		*agibp, *agfbp;
+	struct xfs_agi		*agi;
+	struct xfs_agf		*agf;
+	int			error, err2;
+	struct xfs_alloc_arg	args = {
+		.tp	= tp,
+		.mp	= mp,
+		.type	= XFS_ALLOCTYPE_THIS_BNO,
+		.minlen = len,
+		.maxlen = len,
+		.oinfo	= XFS_RMAP_OINFO_SKIP_UPDATE,
+		.resv	= XFS_AG_RESV_NONE,
+		.prod	= 1
+	};
+
+	ASSERT(id->agno == mp->m_sb.sb_agcount - 1);
+	error = xfs_ialloc_read_agi(mp, tp, id->agno, &agibp);
+	if (error)
+		return error;
+
+	agi = agibp->b_addr;
+
+	error = xfs_alloc_read_agf(mp, tp, id->agno, 0, &agfbp);
+	if (error)
+		return error;
+
+	args.fsbno = XFS_AGB_TO_FSB(mp, id->agno,
+				    be32_to_cpu(agi->agi_length) - len);
+
+	/* remove the preallocations before allocation and re-establish then */
+	error = xfs_ag_resv_free(agibp->b_pag);
+	if (error)
+		return error;
+
+	/* internal log shouldn't also show up in the free space btrees */
+	error = xfs_alloc_vextent(&args);
+	if (error)
+		goto out;
+
+	if (args.agbno == NULLAGBLOCK) {
+		error = -ENOSPC;
+		goto out;
+	}
+
+	/* Change the agi length */
+	be32_add_cpu(&agi->agi_length, -len);
+	xfs_ialloc_log_agi(tp, agibp, XFS_AGI_LENGTH);
+
+	/* Change agf length */
+	agf = agfbp->b_addr;
+	be32_add_cpu(&agf->agf_length, -len);
+	ASSERT(agf->agf_length == agi->agi_length);
+	xfs_alloc_log_agf(tp, agfbp, XFS_AGF_LENGTH);
+
+out:
+	err2 = xfs_ag_resv_init(agibp->b_pag, tp);
+	if (err2 && err2 != -ENOSPC) {
+		xfs_warn(mp,
+"Error %d reserving per-AG metadata reserve pool.", err2);
+		xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+		return err2;
+	}
+	return error;
+}
+
 /*
  * Extent the AG indicated by the @id by the length passed in
  */
diff --git a/fs/xfs/libxfs/xfs_ag.h b/fs/xfs/libxfs/xfs_ag.h
index 5166322807e7..f3b5bbfeadce 100644
--- a/fs/xfs/libxfs/xfs_ag.h
+++ b/fs/xfs/libxfs/xfs_ag.h
@@ -24,6 +24,8 @@  struct aghdr_init_data {
 };
 
 int xfs_ag_init_headers(struct xfs_mount *mp, struct aghdr_init_data *id);
+int xfs_ag_shrink_space(struct xfs_mount *mp, struct xfs_trans *tp,
+			struct aghdr_init_data *id, xfs_extlen_t len);
 int xfs_ag_extend_space(struct xfs_mount *mp, struct xfs_trans *tp,
 			struct aghdr_init_data *id, xfs_extlen_t len);
 int xfs_ag_get_geometry(struct xfs_mount *mp, xfs_agnumber_t agno,
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index a792d1f0ac55..eea38395e804 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -79,19 +79,22 @@  xfs_growfs_data_private(
 	xfs_rfsblock_t		delta;
 	xfs_agnumber_t		oagcount;
 	struct xfs_trans	*tp;
+	bool			extend;
 	struct aghdr_init_data	id = {};
 
 	nb = in->newblocks;
-	if (nb < mp->m_sb.sb_dblocks)
-		return -EINVAL;
-	if ((error = xfs_sb_validate_fsb_count(&mp->m_sb, nb)))
+	error = xfs_sb_validate_fsb_count(&mp->m_sb, nb);
+	if (error)
 		return error;
-	error = xfs_buf_read_uncached(mp->m_ddev_targp,
+
+	if (nb > mp->m_sb.sb_dblocks) {
+		error = xfs_buf_read_uncached(mp->m_ddev_targp,
 				XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
 				XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
-	if (error)
-		return error;
-	xfs_buf_relse(bp);
+		if (error)
+			return error;
+		xfs_buf_relse(bp);
+	}
 
 	delta = nb;	/* use delta as a temporary here */
 	nb_mod = do_div(delta, mp->m_sb.sb_agblocks);
@@ -99,10 +102,18 @@  xfs_growfs_data_private(
 	if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) {
 		nagcount--;
 		nb = (xfs_rfsblock_t)nagcount * mp->m_sb.sb_agblocks;
-		if (nb < mp->m_sb.sb_dblocks)
+		if (nagcount < 2)
 			return -EINVAL;
 	}
-	delta = nb - mp->m_sb.sb_dblocks;
+
+	if (nb > mp->m_sb.sb_dblocks) {
+		delta = nb - mp->m_sb.sb_dblocks;
+		extend = true;
+	} else {
+		delta = mp->m_sb.sb_dblocks - nb;
+		extend = false;
+	}
+
 	oagcount = mp->m_sb.sb_agcount;
 
 	/* allocate the new per-ag structures */
@@ -110,22 +121,34 @@  xfs_growfs_data_private(
 		error = xfs_initialize_perag(mp, nagcount, &nagimax);
 		if (error)
 			return error;
+	} else if (nagcount != oagcount) {
+		/* TODO: shrinking the entire AGs hasn't yet completed */
+		return -EINVAL;
 	}
 
 	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata,
-			XFS_GROWFS_SPACE_RES(mp), 0, XFS_TRANS_RESERVE, &tp);
+			(extend ? XFS_GROWFS_SPACE_RES(mp) : delta), 0,
+			XFS_TRANS_RESERVE, &tp);
 	if (error)
 		return error;
 
-	error = xfs_resizefs_init_new_ags(mp, &id, oagcount, nagcount, &delta);
-	if (error)
-		goto out_trans_cancel;
-
+	if (extend) {
+		error = xfs_resizefs_init_new_ags(mp, &id, oagcount,
+						  nagcount, &delta);
+		if (error)
+			goto out_trans_cancel;
+	}
 	xfs_trans_agblocks_delta(tp, id.nfree);
 
-	/* If there are new blocks in the old last AG, extend it. */
+	/* If there are some blocks in the last AG, resize it. */
 	if (delta) {
-		error = xfs_ag_extend_space(mp, tp, &id, delta);
+		if (extend) {
+			error = xfs_ag_extend_space(mp, tp, &id, delta);
+		} else {
+			id.agno = nagcount - 1;
+			error = xfs_ag_shrink_space(mp, tp, &id, delta);
+		}
+
 		if (error)
 			goto out_trans_cancel;
 	}
@@ -137,11 +160,19 @@  xfs_growfs_data_private(
 	 */
 	if (nagcount > oagcount)
 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
-	if (nb > mp->m_sb.sb_dblocks)
+	if (nb != mp->m_sb.sb_dblocks)
 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS,
 				 nb - mp->m_sb.sb_dblocks);
 	if (id.nfree)
 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, id.nfree);
+
+	/*
+	 * update in-core counters (especially sb_fdblocks) now
+	 * so xfs_validate_sb_write() can pass.
+	 */
+	if (xfs_sb_version_haslazysbcount(&mp->m_sb))
+		xfs_log_sb(tp);
+
 	xfs_trans_set_sync(tp);
 	error = xfs_trans_commit(tp);
 	if (error)
@@ -178,6 +209,10 @@  xfs_growfs_data_private(
 	return error;
 
 out_trans_cancel:
+	if (!extend && (tp->t_flags & XFS_TRANS_DIRTY)) {
+		xfs_trans_commit(tp);
+		return error;
+	}
 	xfs_trans_cancel(tp);
 	return error;
 }
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index e72730f85af1..fd2cbf414b80 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -419,7 +419,6 @@  xfs_trans_mod_sb(
 		tp->t_res_frextents_delta += delta;
 		break;
 	case XFS_TRANS_SB_DBLOCKS:
-		ASSERT(delta > 0);
 		tp->t_dblocks_delta += delta;
 		break;
 	case XFS_TRANS_SB_AGCOUNT: