xfs: refactor xfs_ialloc_ag_select

Loop over the in-core perag structures and prefer using pagi_freecount over going out to the AGI buffer where possible. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>

xfs: refactor xfs_ialloc_ag_select
Loop over the in-core perag structures and prefer using pagi_freecount over going out to the AGI buffer where possible. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
Christoph Hellwig · Ben Myers
1 parent 4bb61069d2
Showing 1 changed file with 44 additions and 51 deletions Side-by-side Diff
fs/xfs/xfs_ialloc.c
@@ -442,14 +442,13 @@
  * Select an allocation group to look for a free inode in, based on the parent
  * inode and then mode.  Return the allocation group buffer.
  */
-STATIC xfs_buf_t *			/* allocation group buffer */
+STATIC xfs_agnumber_t
 xfs_ialloc_ag_select(
 	xfs_trans_t	*tp,		/* transaction pointer */
 	xfs_ino_t	parent,		/* parent directory inode number */
 	umode_t		mode,		/* bits set to indicate file type */
 	int		okalloc)	/* ok to allocate more space */
 {
-	xfs_buf_t	*agbp;		/* allocation group header buffer */
 	xfs_agnumber_t	agcount;	/* number of ag's in the filesystem */
 	xfs_agnumber_t	agno;		/* current ag number */
 	int		flags;		/* alloc buffer locking flags */
@@ -459,6 +458,7 @@
 	int		needspace;	/* file mode implies space allocated */
 	xfs_perag_t	*pag;		/* per allocation group data */
 	xfs_agnumber_t	pagno;		/* parent (starting) ag number */
+	int		error;
  
 	/*
 	 * Files of these types need at least one block if length > 0
  
@@ -474,7 +474,9 @@
 		if (pagno >= agcount)
 			pagno = 0;
 	}
+
 	ASSERT(pagno < agcount);
+
 	/*
 	 * Loop through allocation groups, looking for one with a little
 	 * free space in it.  Note we don't look for free inodes, exactly.
  
  
  
  
  
  
  
@@ -486,51 +488,45 @@
 	flags = XFS_ALLOC_FLAG_TRYLOCK;
 	for (;;) {
 		pag = xfs_perag_get(mp, agno);
+		if (!pag->pagi_inodeok) {
+			xfs_ialloc_next_ag(mp);
+			goto nextag;
+		}
+
 		if (!pag->pagi_init) {
-			if (xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
-				agbp = NULL;
+			error = xfs_ialloc_pagi_init(mp, tp, agno);
+			if (error)
 				goto nextag;
-			}
-		} else
-			agbp = NULL;
+		}
  
-		if (!pag->pagi_inodeok) {
-			xfs_ialloc_next_ag(mp);
-			goto unlock_nextag;
+		if (pag->pagi_freecount) {
+			xfs_perag_put(pag);
+			return agno;
 		}
  
+		if (!okalloc)
+			goto nextag;
+
+		if (!pag->pagf_init) {
+			error = xfs_alloc_pagf_init(mp, tp, agno, flags);
+			if (error)
+				goto nextag;
+		}
+
 		/*
-		 * Is there enough free space for the file plus a block
-		 * of inodes (if we need to allocate some)?
+		 * Is there enough free space for the file plus a block of
+		 * inodes? (if we need to allocate some)?
 		 */
-		ineed = pag->pagi_freecount ? 0 : XFS_IALLOC_BLOCKS(mp);
-		if (ineed && !pag->pagf_init) {
-			if (agbp == NULL &&
-			    xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
-				agbp = NULL;
-				goto nextag;
-			}
-			(void)xfs_alloc_pagf_init(mp, tp, agno, flags);
+		ineed = XFS_IALLOC_BLOCKS(mp);
+		longest = pag->pagf_longest;
+		if (!longest)
+			longest = pag->pagf_flcount > 0;
+
+		if (pag->pagf_freeblks >= needspace + ineed &&
+		    longest >= ineed) {
+			xfs_perag_put(pag);
+			return agno;
 		}
-		if (!ineed || pag->pagf_init) {
-			if (ineed && !(longest = pag->pagf_longest))
-				longest = pag->pagf_flcount > 0;
-			if (!ineed ||
-			    (pag->pagf_freeblks >= needspace + ineed &&
-			     longest >= ineed &&
-			     okalloc)) {
-				if (agbp == NULL &&
-				    xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
-					agbp = NULL;
-					goto nextag;
-				}
-				xfs_perag_put(pag);
-				return agbp;
-			}
-		}
-unlock_nextag:
-		if (agbp)
-			xfs_trans_brelse(tp, agbp);
 nextag:
 		xfs_perag_put(pag);
 		/*
  
@@ -538,13 +534,13 @@
 		 * down.
 		 */
 		if (XFS_FORCED_SHUTDOWN(mp))
-			return NULL;
+			return NULLAGNUMBER;
 		agno++;
 		if (agno >= agcount)
 			agno = 0;
 		if (agno == pagno) {
 			if (flags == 0)
-				return NULL;
+				return NULLAGNUMBER;
 			flags = 0;
 		}
 	}
  
@@ -901,13 +897,13 @@
 	struct xfs_buf		**IO_agbp,
 	xfs_ino_t		*inop)
 {
+	struct xfs_mount	*mp = tp->t_mountp;
 	struct xfs_buf		*agbp;
 	xfs_agnumber_t		agno;
 	struct xfs_agi		*agi;
 	int			error;
 	int			ialloced;
 	int			noroom = 0;
-	struct xfs_mount	*mp;
 	xfs_agnumber_t		tagno;
 	struct xfs_perag	*pag;
  
  
  
@@ -925,20 +921,17 @@
 	 * We do not have an agbp, so select an initial allocation
 	 * group for inode allocation.
 	 */
-	agbp = xfs_ialloc_ag_select(tp, parent, mode, okalloc);
-
-	/*
-	 * Couldn't find an allocation group satisfying the
-	 * criteria, give up.
-	 */
-	if (!agbp) {
+	agno = xfs_ialloc_ag_select(tp, parent, mode, okalloc);
+	if (agno == NULLAGNUMBER) {
 		*inop = NULLFSINO;
 		return 0;
 	}
+
+	error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
+	if (error)
+		return XFS_ERROR(error);
 	agi = XFS_BUF_TO_AGI(agbp);
  
-	mp = tp->t_mountp;
-	agno = be32_to_cpu(agi->agi_seqno);
 	tagno = agno;
  
 	/*
...	...	@@ -442,14 +442,13 @@
442	442	* Select an allocation group to look for a free inode in, based on the parent
443	443	* inode and then mode. Return the allocation group buffer.
444	444	*/
445		-STATIC xfs_buf_t * /* allocation group buffer */
	445	+STATIC xfs_agnumber_t
446	446	xfs_ialloc_ag_select(
447	447	xfs_trans_t tp, / transaction pointer */
448	448	xfs_ino_t parent, /* parent directory inode number */
449	449	umode_t mode, /* bits set to indicate file type */
450	450	int okalloc) /* ok to allocate more space */
451	451	{
452		- xfs_buf_t agbp; / allocation group header buffer */
453	452	xfs_agnumber_t agcount; /* number of ag's in the filesystem */
454	453	xfs_agnumber_t agno; /* current ag number */
455	454	int flags; /* alloc buffer locking flags */
...	...	@@ -459,6 +458,7 @@
459	458	int needspace; /* file mode implies space allocated */
460	459	xfs_perag_t pag; / per allocation group data */
461	460	xfs_agnumber_t pagno; /* parent (starting) ag number */
	461	+ int error;
462	462
463	463	/*
464	464	* Files of these types need at least one block if length > 0
465	465
...	...	@@ -474,7 +474,9 @@
474	474	if (pagno >= agcount)
475	475	pagno = 0;
476	476	}
	477	+
477	478	ASSERT(pagno < agcount);
	479	+
478	480	/*
479	481	* Loop through allocation groups, looking for one with a little
480	482	* free space in it. Note we don't look for free inodes, exactly.
481	483
482	484
483	485
484	486
485	487
486	488
487	489
...	...	@@ -486,51 +488,45 @@
486	488	flags = XFS_ALLOC_FLAG_TRYLOCK;
487	489	for (;;) {
488	490	pag = xfs_perag_get(mp, agno);
	491	+ if (!pag->pagi_inodeok) {
	492	+ xfs_ialloc_next_ag(mp);
	493	+ goto nextag;
	494	+ }
	495	+
489	496	if (!pag->pagi_init) {
490		- if (xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
491		- agbp = NULL;
	497	+ error = xfs_ialloc_pagi_init(mp, tp, agno);
	498	+ if (error)
492	499	goto nextag;
493		- }
494		- } else
495		- agbp = NULL;
	500	+ }
496	501
497		- if (!pag->pagi_inodeok) {
498		- xfs_ialloc_next_ag(mp);
499		- goto unlock_nextag;
	502	+ if (pag->pagi_freecount) {
	503	+ xfs_perag_put(pag);
	504	+ return agno;
500	505	}
501	506
	507	+ if (!okalloc)
	508	+ goto nextag;
	509	+
	510	+ if (!pag->pagf_init) {
	511	+ error = xfs_alloc_pagf_init(mp, tp, agno, flags);
	512	+ if (error)
	513	+ goto nextag;
	514	+ }
	515	+
502	516	/*
503		- * Is there enough free space for the file plus a block
504		- * of inodes (if we need to allocate some)?
	517	+ * Is there enough free space for the file plus a block of
	518	+ * inodes? (if we need to allocate some)?
505	519	*/
506		- ineed = pag->pagi_freecount ? 0 : XFS_IALLOC_BLOCKS(mp);
507		- if (ineed && !pag->pagf_init) {
508		- if (agbp == NULL &&
509		- xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
510		- agbp = NULL;
511		- goto nextag;
512		- }
513		- (void)xfs_alloc_pagf_init(mp, tp, agno, flags);
	520	+ ineed = XFS_IALLOC_BLOCKS(mp);
	521	+ longest = pag->pagf_longest;
	522	+ if (!longest)
	523	+ longest = pag->pagf_flcount > 0;
	524	+
	525	+ if (pag->pagf_freeblks >= needspace + ineed &&
	526	+ longest >= ineed) {
	527	+ xfs_perag_put(pag);
	528	+ return agno;
514	529	}
515		- if (!ineed \|\| pag->pagf_init) {
516		- if (ineed && !(longest = pag->pagf_longest))
517		- longest = pag->pagf_flcount > 0;
518		- if (!ineed \|\|
519		- (pag->pagf_freeblks >= needspace + ineed &&
520		- longest >= ineed &&
521		- okalloc)) {
522		- if (agbp == NULL &&
523		- xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
524		- agbp = NULL;
525		- goto nextag;
526		- }
527		- xfs_perag_put(pag);
528		- return agbp;
529		- }
530		- }
531		-unlock_nextag:
532		- if (agbp)
533		- xfs_trans_brelse(tp, agbp);
534	530	nextag:
535	531	xfs_perag_put(pag);
536	532	/*
537	533
...	...	@@ -538,13 +534,13 @@
538	534	* down.
539	535	*/
540	536	if (XFS_FORCED_SHUTDOWN(mp))
541		- return NULL;
	537	+ return NULLAGNUMBER;
542	538	agno++;
543	539	if (agno >= agcount)
544	540	agno = 0;
545	541	if (agno == pagno) {
546	542	if (flags == 0)
547		- return NULL;
	543	+ return NULLAGNUMBER;
548	544	flags = 0;
549	545	}
550	546	}
551	547
...	...	@@ -901,13 +897,13 @@
901	897	struct xfs_buf **IO_agbp,
902	898	xfs_ino_t *inop)
903	899	{
	900	+ struct xfs_mount *mp = tp->t_mountp;
904	901	struct xfs_buf *agbp;
905	902	xfs_agnumber_t agno;
906	903	struct xfs_agi *agi;
907	904	int error;
908	905	int ialloced;
909	906	int noroom = 0;
910		- struct xfs_mount *mp;
911	907	xfs_agnumber_t tagno;
912	908	struct xfs_perag *pag;
913	909
914	910
915	911
...	...	@@ -925,20 +921,17 @@
925	921	* We do not have an agbp, so select an initial allocation
926	922	* group for inode allocation.
927	923	*/
928		- agbp = xfs_ialloc_ag_select(tp, parent, mode, okalloc);
929		-
930		- /*
931		- * Couldn't find an allocation group satisfying the
932		- * criteria, give up.
933		- */
934		- if (!agbp) {
	924	+ agno = xfs_ialloc_ag_select(tp, parent, mode, okalloc);
	925	+ if (agno == NULLAGNUMBER) {
935	926	*inop = NULLFSINO;
936	927	return 0;
937	928	}
	929	+
	930	+ error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
	931	+ if (error)
	932	+ return XFS_ERROR(error);
938	933	agi = XFS_BUF_TO_AGI(agbp);
939	934
940		- mp = tp->t_mountp;
941		- agno = be32_to_cpu(agi->agi_seqno);
942	935	tagno = agno;
943	936
944	937	/*