diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index 028e44e58ea9..2cf944eb796d 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -1871,6 +1871,25 @@ xfs_alloc_compute_maxlevels(
 	mp->m_ag_maxlevels = level;
 }
 
+/*
+ * Find the length of the longest extent in an AG.
+ */
+xfs_extlen_t
+xfs_alloc_longest_free_extent(
+	struct xfs_mount	*mp,
+	struct xfs_perag	*pag)
+{
+	xfs_extlen_t		need, delta = 0;
+
+	need = XFS_MIN_FREELIST_PAG(pag, mp);
+	if (need > pag->pagf_flcount)
+		delta = need - pag->pagf_flcount;
+
+	if (pag->pagf_longest > delta)
+		return pag->pagf_longest - delta;
+	return pag->pagf_flcount > 0 || pag->pagf_longest > 0;
+}
+
 /*
  * Decide whether to use this allocation group for this allocation.
  * If so, fix up the btree freelist's size.
@@ -1923,15 +1942,12 @@ xfs_alloc_fix_freelist(
 	}
 
 	if (!(flags & XFS_ALLOC_FLAG_FREEING)) {
-		need = XFS_MIN_FREELIST_PAG(pag, mp);
-		delta = need > pag->pagf_flcount ? need - pag->pagf_flcount : 0;
 		/*
 		 * If it looks like there isn't a long enough extent, or enough
 		 * total blocks, reject it.
 		 */
-		longest = (pag->pagf_longest > delta) ?
-			(pag->pagf_longest - delta) :
-			(pag->pagf_flcount > 0 || pag->pagf_longest > 0);
+		need = XFS_MIN_FREELIST_PAG(pag, mp);
+		longest = xfs_alloc_longest_free_extent(mp, pag);
 		if ((args->minlen + args->alignment + args->minalignslop - 1) >
 				longest ||
 		    ((int)(pag->pagf_freeblks + pag->pagf_flcount -
diff --git a/fs/xfs/xfs_alloc.h b/fs/xfs/xfs_alloc.h
index 588172796f7b..e704caee10df 100644
--- a/fs/xfs/xfs_alloc.h
+++ b/fs/xfs/xfs_alloc.h
@@ -100,6 +100,12 @@ typedef struct xfs_alloc_arg {
 #define XFS_ALLOC_USERDATA		1	/* allocation is for user data*/
 #define XFS_ALLOC_INITIAL_USER_DATA	2	/* special case start of file */
 
+/*
+ * Find the length of the longest extent in an AG.
+ */
+xfs_extlen_t
+xfs_alloc_longest_free_extent(struct xfs_mount *mp,
+		struct xfs_perag *pag);
 
 #ifdef __KERNEL__
 
diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 27062d0a879d..07b7d0d59d88 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -2712,9 +2712,6 @@ xfs_bmap_btalloc(
 	xfs_agnumber_t	startag;
 	xfs_alloc_arg_t	args;
 	xfs_extlen_t	blen;
-	xfs_extlen_t	delta;
-	xfs_extlen_t	longest;
-	xfs_extlen_t	need;
 	xfs_extlen_t	nextminlen = 0;
 	xfs_perag_t	*pag;
 	int		nullfb;		/* true if ap->firstblock isn't set */
@@ -2796,13 +2793,8 @@ xfs_bmap_btalloc(
 			 * See xfs_alloc_fix_freelist...
 			 */
 			if (pag->pagf_init) {
-				need = XFS_MIN_FREELIST_PAG(pag, mp);
-				delta = need > pag->pagf_flcount ?
-					need - pag->pagf_flcount : 0;
-				longest = (pag->pagf_longest > delta) ?
-					(pag->pagf_longest - delta) :
-					(pag->pagf_flcount > 0 ||
-					 pag->pagf_longest > 0);
+				xfs_extlen_t	longest;
+				longest = xfs_alloc_longest_free_extent(mp, pag);
 				if (blen < longest)
 					blen = longest;
 			} else
diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c
index f3bb75da384e..6c87c8f304ef 100644
--- a/fs/xfs/xfs_filestream.c
+++ b/fs/xfs/xfs_filestream.c
@@ -140,7 +140,7 @@ _xfs_filestream_pick_ag(
 	xfs_extlen_t	minlen)
 {
 	int		err, trylock, nscan;
-	xfs_extlen_t	delta, longest, need, free, minfree, maxfree = 0;
+	xfs_extlen_t	longest, free, minfree, maxfree = 0;
 	xfs_agnumber_t	ag, max_ag = NULLAGNUMBER;
 	struct xfs_perag *pag;
 
@@ -186,12 +186,7 @@ _xfs_filestream_pick_ag(
 			goto next_ag;
 		}
 
-		need = XFS_MIN_FREELIST_PAG(pag, mp);
-		delta = need > pag->pagf_flcount ? need - pag->pagf_flcount : 0;
-		longest = (pag->pagf_longest > delta) ?
-		          (pag->pagf_longest - delta) :
-		          (pag->pagf_flcount > 0 || pag->pagf_longest > 0);
-
+		longest = xfs_alloc_longest_free_extent(mp, pag);
 		if (((minlen && longest >= minlen) ||
 		     (!minlen && pag->pagf_freeblks >= minfree)) &&
 		    (!pag->pagf_metadata || !(flags & XFS_PICK_USERDATA) ||