diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 95bfe89651add0e260964d756fb295f9a9872d04..23c0e666d2f49389266fb9c0adf4c5a9466b7cb2 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -408,20 +408,18 @@ xfs_alloc_compute_diff(
  * Fix up the length, based on mod and prod.
  * len should be k * prod + mod for some k.
  * If len is too small it is returned unchanged.
- * If len hits maxlen it is left alone.
  */
-STATIC void
+static void
 xfs_alloc_fix_len(
-	xfs_alloc_arg_t	*args)		/* allocation argument structure */
+	struct xfs_alloc_arg	*args)
 {
-	xfs_extlen_t	k;
-	xfs_extlen_t	rlen;
+	xfs_extlen_t		k;
+	xfs_extlen_t		rlen = args->len;
 
 	ASSERT(args->mod < args->prod);
-	rlen = args->len;
 	ASSERT(rlen >= args->minlen);
 	ASSERT(rlen <= args->maxlen);
-	if (args->prod <= 1 || rlen < args->mod || rlen == args->maxlen ||
+	if (args->prod <= 1 || rlen < args->mod ||
 	    (args->mod == 0 && rlen < args->prod))
 		return;
 	k = rlen % args->prod;
@@ -2385,14 +2383,23 @@ xfs_alloc_space_available(
 	if (available < (int)max(args->total, alloc_len))
 		return false;
 
+	if (flags & XFS_ALLOC_FLAG_CHECK)
+		return true;
+
 	/*
-	 * Clamp maxlen to the amount of free space available for the actual
-	 * extent allocation.
+	 * If we can't do a maxlen allocation, then we must reduce the size of
+	 * the allocation to match the available free space. We know how big
+	 * the largest contiguous free space we can allocate is, so that's our
+	 * upper bound. However, we don't exaclty know what alignment/size
+	 * constraints have been placed on the allocation, so we can't
+	 * arbitrarily select some new max size. Hence make this a minlen
+	 * allocation as we know that will definitely succeed and match the
+	 * callers alignment constraints.
 	 */
-	if (available < (int)args->maxlen && !(flags & XFS_ALLOC_FLAG_CHECK)) {
-		args->maxlen = available;
+	alloc_len = args->maxlen + (args->alignment - 1) + args->minalignslop;
+	if (longest < alloc_len) {
+		args->maxlen = args->minlen;
 		ASSERT(args->maxlen > 0);
-		ASSERT(args->maxlen >= args->minlen);
 	}
 
 	return true;
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 7682dfe2f7010b73bf3e6fa4d3f65b9892b2c339..bf09737cfc712949a1d910879f557a76b3ec2087 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -3253,32 +3253,47 @@ xfs_bmap_longest_free_extent(
 	return error;
 }
 
-static void
+static int
 xfs_bmap_select_minlen(
 	struct xfs_bmalloca	*ap,
 	struct xfs_alloc_arg	*args,
 	xfs_extlen_t		*blen,
 	int			notinit)
 {
+	xfs_extlen_t nlen = 0;
+
 	if (notinit || *blen < ap->minlen) {
 		/*
 		 * Since we did a BUF_TRYLOCK above, it is possible that
 		 * there is space for this request.
 		 */
-		args->minlen = ap->minlen;
+		nlen = ap->minlen;
 	} else if (*blen < args->maxlen) {
 		/*
 		 * If the best seen length is less than the request length,
 		 * use the best as the minimum.
 		 */
-		args->minlen = *blen;
+
+		nlen = *blen;
 	} else {
 		/*
 		 * Otherwise we've seen an extent as big as maxlen, use that
 		 * as the minimum.
 		 */
-		args->minlen = args->maxlen;
+		nlen = args->maxlen;
+	}
+
+	if (args->alignment > 1) {
+		nlen = rounddown(nlen, args->alignment);
+		if (nlen < ap->minlen) {
+			if (xfs_inode_forcealign(ap->ip) &&
+				(ap->datatype & XFS_ALLOC_USERDATA))
+				return -ENOSPC;
+			nlen = ap->minlen;
+		}
 	}
+	args->minlen = nlen;
+	return 0;
 }
 
 STATIC int
@@ -3311,8 +3326,8 @@ xfs_bmap_btalloc_nullfb(
 			break;
 	}
 
-	xfs_bmap_select_minlen(ap, args, blen, notinit);
-	return 0;
+	error = xfs_bmap_select_minlen(ap, args, blen, notinit);
+	return error;
 }
 
 STATIC int
@@ -3349,7 +3364,9 @@ xfs_bmap_btalloc_filestreams(
 
 	}
 
-	xfs_bmap_select_minlen(ap, args, blen, notinit);
+	error = xfs_bmap_select_minlen(ap, args, blen, notinit);
+	if (error)
+		return error;
 
 	/*
 	 * Set the failure fallback case to look in the selected AG as stream
@@ -3493,6 +3510,7 @@ xfs_bmap_btalloc(
 	 */
 	if (xfs_inode_forcealign(ap->ip) && align) {
 		args.alignment = align;
+		args.minlen = ap->minlen = align;
 		if (stripe_align == 0 || stripe_align % align)
 			stripe_align = align;
 	} else {
@@ -3669,10 +3687,12 @@ xfs_bmap_btalloc(
 		 * very fragmented so we're unlikely to be able to satisfy the
 		 * hints anyway.
 		 */
-		if (ap->length <= orig_length)
-			ap->offset = orig_offset;
-		else if (ap->offset + ap->length < orig_offset + orig_length)
-			ap->offset = orig_offset + orig_length - ap->length;
+		if (!(xfs_inode_forcealign(ap->ip) && align)) {
+			if (ap->length <= orig_length)
+				ap->offset = orig_offset;
+			else if (ap->offset + ap->length < orig_offset + orig_length)
+				ap->offset = orig_offset + orig_length - ap->length;
+		}
 		xfs_bmap_btalloc_accounting(ap, &args);
 	} else {
 		ap->blkno = NULLFSBLOCK;