diff mbox series

[23/42] xfs: introduce xfs_alloc_vextent_exact_bno()

Message ID 20230118224505.1964941-24-david@fromorbit.com (mailing list archive)
State Superseded
Headers show
Series xfs: per-ag centric allocation alogrithms | expand

Commit Message

Dave Chinner Jan. 18, 2023, 10:44 p.m. UTC 
From: Dave Chinner <dchinner@redhat.com>

Two of the callers to xfs_alloc_vextent_this_ag() actually want
exact block number allocation, not anywhere-in-ag allocation. Split
this out from _this_ag() as a first class citizen so no external
extent allocation code needs to care about args->type anymore.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/libxfs/xfs_ag.c     |  6 ++--
 fs/xfs/libxfs/xfs_alloc.c  | 65 ++++++++++++++++++++++++++++++++------
 fs/xfs/libxfs/xfs_alloc.h  | 13 ++++++--
 fs/xfs/libxfs/xfs_bmap.c   |  6 ++--
 fs/xfs/libxfs/xfs_ialloc.c |  6 ++--
 fs/xfs/scrub/repair.c      |  4 +--
 6 files changed, 73 insertions(+), 27 deletions(-)

Comments

Darrick J. Wong Feb. 1, 2023, 11 p.m. UTC | #1 
On Thu, Jan 19, 2023 at 09:44:46AM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> Two of the callers to xfs_alloc_vextent_this_ag() actually want
> exact block number allocation, not anywhere-in-ag allocation. Split
> this out from _this_ag() as a first class citizen so no external
> extent allocation code needs to care about args->type anymore.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  fs/xfs/libxfs/xfs_ag.c     |  6 ++--
>  fs/xfs/libxfs/xfs_alloc.c  | 65 ++++++++++++++++++++++++++++++++------
>  fs/xfs/libxfs/xfs_alloc.h  | 13 ++++++--
>  fs/xfs/libxfs/xfs_bmap.c   |  6 ++--
>  fs/xfs/libxfs/xfs_ialloc.c |  6 ++--
>  fs/xfs/scrub/repair.c      |  4 +--
>  6 files changed, 73 insertions(+), 27 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
> index 053d77a283f7..86696a1c6891 100644
> --- a/fs/xfs/libxfs/xfs_ag.c
> +++ b/fs/xfs/libxfs/xfs_ag.c
> @@ -888,7 +888,6 @@ xfs_ag_shrink_space(
>  		.tp	= *tpp,
>  		.mp	= mp,
>  		.pag	= pag,
> -		.type	= XFS_ALLOCTYPE_THIS_BNO,
>  		.minlen = delta,
>  		.maxlen = delta,
>  		.oinfo	= XFS_RMAP_OINFO_SKIP_UPDATE,
> @@ -920,8 +919,6 @@ xfs_ag_shrink_space(
>  	if (delta >= aglen)
>  		return -EINVAL;
>  
> -	args.fsbno = XFS_AGB_TO_FSB(mp, pag->pag_agno, aglen - delta);
> -
>  	/*
>  	 * Make sure that the last inode cluster cannot overlap with the new
>  	 * end of the AG, even if it's sparse.
> @@ -939,7 +936,8 @@ xfs_ag_shrink_space(
>  		return error;
>  
>  	/* internal log shouldn't also show up in the free space btrees */
> -	error = xfs_alloc_vextent_this_ag(&args);
> +	error = xfs_alloc_vextent_exact_bno(&args,
> +			XFS_AGB_TO_FSB(mp, pag->pag_agno, aglen - delta));
>  	if (!error && args.agbno == NULLAGBLOCK)
>  		error = -ENOSPC;
>  
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index 485a73eab9d9..b810a94aad70 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -3272,28 +3272,34 @@ xfs_alloc_vextent_set_fsbno(
>   */
>  int
>  xfs_alloc_vextent_this_ag(
> -	struct xfs_alloc_arg	*args)
> +	struct xfs_alloc_arg	*args,
> +	xfs_agnumber_t		agno)
>  {
>  	struct xfs_mount	*mp = args->mp;
>  	xfs_agnumber_t		minimum_agno = 0;
> +	xfs_rfsblock_t		target = XFS_AGB_TO_FSB(mp, agno, 0);

Same xfs_rfsblock_t vs. xfs_fsblock_t comment here too.

These conversions look like a good improvement though -- it's very
helpful that we can now look at an xfs_alloc_vextent_* call and know
exactly which behavior we're getting.

--D

>  	int			error;
>  
>  	if (args->tp->t_highest_agno != NULLAGNUMBER)
>  		minimum_agno = args->tp->t_highest_agno;
>  
> -	error = xfs_alloc_vextent_check_args(args, args->fsbno);
> +	if (minimum_agno > agno) {
> +		trace_xfs_alloc_vextent_skip_deadlock(args);
> +		args->fsbno = NULLFSBLOCK;
> +		return 0;
> +	}
> +
> +	error = xfs_alloc_vextent_check_args(args, target);
>  	if (error) {
>  		if (error == -ENOSPC)
>  			return 0;
>  		return error;
>  	}
>  
> -	args->agno = XFS_FSB_TO_AGNO(mp, args->fsbno);
> -	if (minimum_agno > args->agno) {
> -		trace_xfs_alloc_vextent_skip_deadlock(args);
> -		args->fsbno = NULLFSBLOCK;
> -		return 0;
> -	}
> +	args->agno = agno;
> +	args->agbno = 0;
> +	args->fsbno = target;
> +	args->type = XFS_ALLOCTYPE_THIS_AG;
>  
>  	error = xfs_alloc_ag_vextent(args);
>  	xfs_alloc_vextent_set_fsbno(args, minimum_agno);
> @@ -3450,7 +3456,7 @@ xfs_alloc_vextent_start_ag(
>   * pass, so will not recurse into AGs lower than indicated by fsbno.
>   */
>  int
> - xfs_alloc_vextent_first_ag(
> +xfs_alloc_vextent_first_ag(
>  	struct xfs_alloc_arg	*args,
>  	xfs_rfsblock_t		target)
>   {
> @@ -3472,12 +3478,51 @@ int
>  	start_agno = max(minimum_agno, XFS_FSB_TO_AGNO(mp, target));
>  	args->type = XFS_ALLOCTYPE_THIS_AG;
>  	args->fsbno = target;
> -	error =  xfs_alloc_vextent_iterate_ags(args, minimum_agno,
> +	error = xfs_alloc_vextent_iterate_ags(args, minimum_agno,
>  			start_agno, 0);
>  	xfs_alloc_vextent_set_fsbno(args, minimum_agno);
>  	return error;
>  }
>  
> +/*
> + * Allocate within a single AG only.
> + */
> +int
> +xfs_alloc_vextent_exact_bno(
> +	struct xfs_alloc_arg	*args,
> +	xfs_rfsblock_t		target)
> +{
> +	struct xfs_mount	*mp = args->mp;
> +	xfs_agnumber_t		minimum_agno = 0;
> +	int			error;
> +
> +	if (args->tp->t_highest_agno != NULLAGNUMBER)
> +		minimum_agno = args->tp->t_highest_agno;
> +
> +	error = xfs_alloc_vextent_check_args(args, target);
> +	if (error) {
> +		if (error == -ENOSPC)
> +			return 0;
> +		return error;
> +	}
> +
> +	args->agno = XFS_FSB_TO_AGNO(mp, target);
> +	if (minimum_agno > args->agno) {
> +		trace_xfs_alloc_vextent_skip_deadlock(args);
> +		return 0;
> +	}
> +
> +	args->agbno = XFS_FSB_TO_AGBNO(mp, target);
> +	args->fsbno = target;
> +	args->type = XFS_ALLOCTYPE_THIS_BNO;
> +	error = xfs_alloc_ag_vextent(args);
> +	if (error)
> +		return error;
> +
> +	xfs_alloc_vextent_set_fsbno(args, minimum_agno);
> +	return 0;
> +}
> +
>  /*
>   * Allocate an extent as close to the target as possible. If there are not
>   * viable candidates in the AG, then fail the allocation.
> diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h
> index f38a2f8e20fb..106b4deb1110 100644
> --- a/fs/xfs/libxfs/xfs_alloc.h
> +++ b/fs/xfs/libxfs/xfs_alloc.h
> @@ -114,10 +114,10 @@ xfs_alloc_log_agf(
>  	uint32_t	fields);/* mask of fields to be logged (XFS_AGF_...) */
>  
>  /*
> - * Allocate an extent in the specific AG defined by args->fsbno. If there is no
> - * space in that AG, then the allocation will fail.
> + * Allocate an extent anywhere in the specific AG given. If there is no
> + * space matching the requirements in that AG, then the allocation will fail.
>   */
> -int xfs_alloc_vextent_this_ag(struct xfs_alloc_arg *args);
> +int xfs_alloc_vextent_this_ag(struct xfs_alloc_arg *args, xfs_agnumber_t agno);
>  
>  /*
>   * Allocate an extent as close to the target as possible. If there are not
> @@ -126,6 +126,13 @@ int xfs_alloc_vextent_this_ag(struct xfs_alloc_arg *args);
>  int xfs_alloc_vextent_near_bno(struct xfs_alloc_arg *args,
>  		xfs_rfsblock_t target);
>  
> +/*
> + * Allocate an extent exactly at the target given. If this is not possible
> + * then the allocation fails.
> + */
> +int xfs_alloc_vextent_exact_bno(struct xfs_alloc_arg *args,
> +		xfs_rfsblock_t target);
> +
>  /*
>   * Best effort full filesystem allocation scan.
>   *
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 4446b035eed5..c9902df16e25 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -3514,7 +3514,6 @@ xfs_bmap_btalloc_at_eof(
>  		xfs_extlen_t	nextminlen = 0;
>  
>  		atype = args->type;
> -		args->type = XFS_ALLOCTYPE_THIS_BNO;
>  		args->alignment = 1;
>  
>  		/*
> @@ -3532,8 +3531,8 @@ xfs_bmap_btalloc_at_eof(
>  		else
>  			args->minalignslop = 0;
>  
> -		args->pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, args->fsbno));
> -		error = xfs_alloc_vextent_this_ag(args);
> +		args->pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, ap->blkno));
> +		error = xfs_alloc_vextent_exact_bno(args, ap->blkno);
>  		xfs_perag_put(args->pag);
>  		if (error)
>  			return error;
> @@ -3546,7 +3545,6 @@ xfs_bmap_btalloc_at_eof(
>  		 */
>  		args->pag = NULL;
>  		args->type = atype;
> -		args->fsbno = ap->blkno;
>  		args->alignment = stripe_align;
>  		args->minlen = nextminlen;
>  		args->minalignslop = 0;
> diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
> index daa6f7055bba..d2525f0cc6cd 100644
> --- a/fs/xfs/libxfs/xfs_ialloc.c
> +++ b/fs/xfs/libxfs/xfs_ialloc.c
> @@ -662,8 +662,6 @@ xfs_ialloc_ag_alloc(
>  		goto sparse_alloc;
>  	if (likely(newino != NULLAGINO &&
>  		  (args.agbno < be32_to_cpu(agi->agi_length)))) {
> -		args.fsbno = XFS_AGB_TO_FSB(args.mp, pag->pag_agno, args.agbno);
> -		args.type = XFS_ALLOCTYPE_THIS_BNO;
>  		args.prod = 1;
>  
>  		/*
> @@ -684,7 +682,9 @@ xfs_ialloc_ag_alloc(
>  
>  		/* Allow space for the inode btree to split. */
>  		args.minleft = igeo->inobt_maxlevels;
> -		error = xfs_alloc_vextent_this_ag(&args);
> +		error = xfs_alloc_vextent_exact_bno(&args,
> +				XFS_AGB_TO_FSB(args.mp, pag->pag_agno,
> +						args.agbno));
>  		if (error)
>  			return error;
>  
> diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
> index 5f4b50aac4bb..1b71174ec0d6 100644
> --- a/fs/xfs/scrub/repair.c
> +++ b/fs/xfs/scrub/repair.c
> @@ -328,14 +328,12 @@ xrep_alloc_ag_block(
>  	args.mp = sc->mp;
>  	args.pag = sc->sa.pag;
>  	args.oinfo = *oinfo;
> -	args.fsbno = XFS_AGB_TO_FSB(args.mp, sc->sa.pag->pag_agno, 0);
>  	args.minlen = 1;
>  	args.maxlen = 1;
>  	args.prod = 1;
> -	args.type = XFS_ALLOCTYPE_THIS_AG;
>  	args.resv = resv;
>  
> -	error = xfs_alloc_vextent_this_ag(&args);
> +	error = xfs_alloc_vextent_this_ag(&args, sc->sa.pag->pag_agno);
>  	if (error)
>  		return error;
>  	if (args.fsbno == NULLFSBLOCK)
> -- 
> 2.39.0
>
diff mbox series

Patch

diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index 053d77a283f7..86696a1c6891 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -888,7 +888,6 @@  xfs_ag_shrink_space(
 		.tp	= *tpp,
 		.mp	= mp,
 		.pag	= pag,
-		.type	= XFS_ALLOCTYPE_THIS_BNO,
 		.minlen = delta,
 		.maxlen = delta,
 		.oinfo	= XFS_RMAP_OINFO_SKIP_UPDATE,
@@ -920,8 +919,6 @@  xfs_ag_shrink_space(
 	if (delta >= aglen)
 		return -EINVAL;
 
-	args.fsbno = XFS_AGB_TO_FSB(mp, pag->pag_agno, aglen - delta);
-
 	/*
 	 * Make sure that the last inode cluster cannot overlap with the new
 	 * end of the AG, even if it's sparse.
@@ -939,7 +936,8 @@  xfs_ag_shrink_space(
 		return error;
 
 	/* internal log shouldn't also show up in the free space btrees */
-	error = xfs_alloc_vextent_this_ag(&args);
+	error = xfs_alloc_vextent_exact_bno(&args,
+			XFS_AGB_TO_FSB(mp, pag->pag_agno, aglen - delta));
 	if (!error && args.agbno == NULLAGBLOCK)
 		error = -ENOSPC;
 
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 485a73eab9d9..b810a94aad70 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -3272,28 +3272,34 @@  xfs_alloc_vextent_set_fsbno(
  */
 int
 xfs_alloc_vextent_this_ag(
-	struct xfs_alloc_arg	*args)
+	struct xfs_alloc_arg	*args,
+	xfs_agnumber_t		agno)
 {
 	struct xfs_mount	*mp = args->mp;
 	xfs_agnumber_t		minimum_agno = 0;
+	xfs_rfsblock_t		target = XFS_AGB_TO_FSB(mp, agno, 0);
 	int			error;
 
 	if (args->tp->t_highest_agno != NULLAGNUMBER)
 		minimum_agno = args->tp->t_highest_agno;
 
-	error = xfs_alloc_vextent_check_args(args, args->fsbno);
+	if (minimum_agno > agno) {
+		trace_xfs_alloc_vextent_skip_deadlock(args);
+		args->fsbno = NULLFSBLOCK;
+		return 0;
+	}
+
+	error = xfs_alloc_vextent_check_args(args, target);
 	if (error) {
 		if (error == -ENOSPC)
 			return 0;
 		return error;
 	}
 
-	args->agno = XFS_FSB_TO_AGNO(mp, args->fsbno);
-	if (minimum_agno > args->agno) {
-		trace_xfs_alloc_vextent_skip_deadlock(args);
-		args->fsbno = NULLFSBLOCK;
-		return 0;
-	}
+	args->agno = agno;
+	args->agbno = 0;
+	args->fsbno = target;
+	args->type = XFS_ALLOCTYPE_THIS_AG;
 
 	error = xfs_alloc_ag_vextent(args);
 	xfs_alloc_vextent_set_fsbno(args, minimum_agno);
@@ -3450,7 +3456,7 @@  xfs_alloc_vextent_start_ag(
  * pass, so will not recurse into AGs lower than indicated by fsbno.
  */
 int
- xfs_alloc_vextent_first_ag(
+xfs_alloc_vextent_first_ag(
 	struct xfs_alloc_arg	*args,
 	xfs_rfsblock_t		target)
  {
@@ -3472,12 +3478,51 @@  int
 	start_agno = max(minimum_agno, XFS_FSB_TO_AGNO(mp, target));
 	args->type = XFS_ALLOCTYPE_THIS_AG;
 	args->fsbno = target;
-	error =  xfs_alloc_vextent_iterate_ags(args, minimum_agno,
+	error = xfs_alloc_vextent_iterate_ags(args, minimum_agno,
 			start_agno, 0);
 	xfs_alloc_vextent_set_fsbno(args, minimum_agno);
 	return error;
 }
 
+/*
+ * Allocate within a single AG only.
+ */
+int
+xfs_alloc_vextent_exact_bno(
+	struct xfs_alloc_arg	*args,
+	xfs_rfsblock_t		target)
+{
+	struct xfs_mount	*mp = args->mp;
+	xfs_agnumber_t		minimum_agno = 0;
+	int			error;
+
+	if (args->tp->t_highest_agno != NULLAGNUMBER)
+		minimum_agno = args->tp->t_highest_agno;
+
+	error = xfs_alloc_vextent_check_args(args, target);
+	if (error) {
+		if (error == -ENOSPC)
+			return 0;
+		return error;
+	}
+
+	args->agno = XFS_FSB_TO_AGNO(mp, target);
+	if (minimum_agno > args->agno) {
+		trace_xfs_alloc_vextent_skip_deadlock(args);
+		return 0;
+	}
+
+	args->agbno = XFS_FSB_TO_AGBNO(mp, target);
+	args->fsbno = target;
+	args->type = XFS_ALLOCTYPE_THIS_BNO;
+	error = xfs_alloc_ag_vextent(args);
+	if (error)
+		return error;
+
+	xfs_alloc_vextent_set_fsbno(args, minimum_agno);
+	return 0;
+}
+
 /*
  * Allocate an extent as close to the target as possible. If there are not
  * viable candidates in the AG, then fail the allocation.
diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h
index f38a2f8e20fb..106b4deb1110 100644
--- a/fs/xfs/libxfs/xfs_alloc.h
+++ b/fs/xfs/libxfs/xfs_alloc.h
@@ -114,10 +114,10 @@  xfs_alloc_log_agf(
 	uint32_t	fields);/* mask of fields to be logged (XFS_AGF_...) */
 
 /*
- * Allocate an extent in the specific AG defined by args->fsbno. If there is no
- * space in that AG, then the allocation will fail.
+ * Allocate an extent anywhere in the specific AG given. If there is no
+ * space matching the requirements in that AG, then the allocation will fail.
  */
-int xfs_alloc_vextent_this_ag(struct xfs_alloc_arg *args);
+int xfs_alloc_vextent_this_ag(struct xfs_alloc_arg *args, xfs_agnumber_t agno);
 
 /*
  * Allocate an extent as close to the target as possible. If there are not
@@ -126,6 +126,13 @@  int xfs_alloc_vextent_this_ag(struct xfs_alloc_arg *args);
 int xfs_alloc_vextent_near_bno(struct xfs_alloc_arg *args,
 		xfs_rfsblock_t target);
 
+/*
+ * Allocate an extent exactly at the target given. If this is not possible
+ * then the allocation fails.
+ */
+int xfs_alloc_vextent_exact_bno(struct xfs_alloc_arg *args,
+		xfs_rfsblock_t target);
+
 /*
  * Best effort full filesystem allocation scan.
  *
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 4446b035eed5..c9902df16e25 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -3514,7 +3514,6 @@  xfs_bmap_btalloc_at_eof(
 		xfs_extlen_t	nextminlen = 0;
 
 		atype = args->type;
-		args->type = XFS_ALLOCTYPE_THIS_BNO;
 		args->alignment = 1;
 
 		/*
@@ -3532,8 +3531,8 @@  xfs_bmap_btalloc_at_eof(
 		else
 			args->minalignslop = 0;
 
-		args->pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, args->fsbno));
-		error = xfs_alloc_vextent_this_ag(args);
+		args->pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, ap->blkno));
+		error = xfs_alloc_vextent_exact_bno(args, ap->blkno);
 		xfs_perag_put(args->pag);
 		if (error)
 			return error;
@@ -3546,7 +3545,6 @@  xfs_bmap_btalloc_at_eof(
 		 */
 		args->pag = NULL;
 		args->type = atype;
-		args->fsbno = ap->blkno;
 		args->alignment = stripe_align;
 		args->minlen = nextminlen;
 		args->minalignslop = 0;
diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index daa6f7055bba..d2525f0cc6cd 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -662,8 +662,6 @@  xfs_ialloc_ag_alloc(
 		goto sparse_alloc;
 	if (likely(newino != NULLAGINO &&
 		  (args.agbno < be32_to_cpu(agi->agi_length)))) {
-		args.fsbno = XFS_AGB_TO_FSB(args.mp, pag->pag_agno, args.agbno);
-		args.type = XFS_ALLOCTYPE_THIS_BNO;
 		args.prod = 1;
 
 		/*
@@ -684,7 +682,9 @@  xfs_ialloc_ag_alloc(
 
 		/* Allow space for the inode btree to split. */
 		args.minleft = igeo->inobt_maxlevels;
-		error = xfs_alloc_vextent_this_ag(&args);
+		error = xfs_alloc_vextent_exact_bno(&args,
+				XFS_AGB_TO_FSB(args.mp, pag->pag_agno,
+						args.agbno));
 		if (error)
 			return error;
 
diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index 5f4b50aac4bb..1b71174ec0d6 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -328,14 +328,12 @@  xrep_alloc_ag_block(
 	args.mp = sc->mp;
 	args.pag = sc->sa.pag;
 	args.oinfo = *oinfo;
-	args.fsbno = XFS_AGB_TO_FSB(args.mp, sc->sa.pag->pag_agno, 0);
 	args.minlen = 1;
 	args.maxlen = 1;
 	args.prod = 1;
-	args.type = XFS_ALLOCTYPE_THIS_AG;
 	args.resv = resv;
 
-	error = xfs_alloc_vextent_this_ag(&args);
+	error = xfs_alloc_vextent_this_ag(&args, sc->sa.pag->pag_agno);
 	if (error)
 		return error;
 	if (args.fsbno == NULLFSBLOCK)