diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index a5e9d7d..c9381bf 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -71,18 +71,23 @@ xfs_zero_extent(
 #ifdef CONFIG_XFS_RT
 int
 xfs_bmap_rtalloc(
-	struct xfs_bmalloca	*ap)	/* bmap alloc argument struct */
+	struct xfs_bmalloca	*ap)
 {
-	int		error;		/* error return value */
-	xfs_mount_t	*mp;		/* mount point structure */
-	xfs_extlen_t	prod = 0;	/* product factor for allocators */
-	xfs_extlen_t	mod = 0;	/* product factor for allocators */
-	xfs_extlen_t	ralen = 0;	/* realtime allocation length */
-	xfs_extlen_t	align;		/* minimum allocation alignment */
-	xfs_rtblock_t	rtb;
+	struct xfs_mount	*mp = ap->ip->i_mount;
+	xfs_fileoff_t		orig_offset = ap->offset;
+	xfs_rtblock_t		rtb;
+	xfs_extlen_t		prod = 0;  /* product factor for allocators */
+	xfs_extlen_t		mod = 0;   /* product factor for allocators */
+	xfs_extlen_t		ralen = 0; /* realtime allocation length */
+	xfs_extlen_t		align;     /* minimum allocation alignment */
+	xfs_extlen_t		orig_length = ap->length;
+	xfs_extlen_t		minlen = mp->m_sb.sb_rextsize;
+	xfs_extlen_t		raminlen;
+	bool			rtlocked = false;
+	int			error;
 
-	mp = ap->ip->i_mount;
 	align = xfs_get_extsz_hint(ap->ip);
+retry:
 	prod = align / mp->m_sb.sb_rextsize;
 	error = xfs_bmap_extsize_align(mp, &ap->got, &ap->prev,
 					align, 1, ap->eof, 0,
@@ -93,6 +98,15 @@ xfs_bmap_rtalloc(
 	ASSERT(ap->length % mp->m_sb.sb_rextsize == 0);
 
 	/*
+	 * If we shifted the file offset downward to satisfy an extent size
+	 * hint, increase minlen by that amount so that the allocator won't
+	 * give us an allocation that's too short to cover at least one of the
+	 * blocks that the caller asked for.
+	 */
+	if (ap->offset != orig_offset)
+		minlen += orig_offset - ap->offset;
+
+	/*
 	 * If the offset & length are not perfectly aligned
 	 * then kill prod, it will just get us in trouble.
 	 */
@@ -116,10 +130,13 @@ xfs_bmap_rtalloc(
 	/*
 	 * Lock out modifications to both the RT bitmap and summary inodes
 	 */
-	xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL|XFS_ILOCK_RTBITMAP);
-	xfs_trans_ijoin(ap->tp, mp->m_rbmip, XFS_ILOCK_EXCL);
-	xfs_ilock(mp->m_rsumip, XFS_ILOCK_EXCL|XFS_ILOCK_RTSUM);
-	xfs_trans_ijoin(ap->tp, mp->m_rsumip, XFS_ILOCK_EXCL);
+	if (!rtlocked) {
+		xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL|XFS_ILOCK_RTBITMAP);
+		xfs_trans_ijoin(ap->tp, mp->m_rbmip, XFS_ILOCK_EXCL);
+		xfs_ilock(mp->m_rsumip, XFS_ILOCK_EXCL|XFS_ILOCK_RTSUM);
+		xfs_trans_ijoin(ap->tp, mp->m_rsumip, XFS_ILOCK_EXCL);
+		rtlocked = true;
+	}
 
 	/*
 	 * If it's an allocation to an empty file at offset 0,
@@ -144,30 +161,44 @@ xfs_bmap_rtalloc(
 	do_div(ap->blkno, mp->m_sb.sb_rextsize);
 	rtb = ap->blkno;
 	ap->length = ralen;
-	error = xfs_rtallocate_extent(ap->tp, ap->blkno, 1, ap->length,
-				&ralen, ap->wasdel, prod, &rtb);
+	raminlen = max_t(xfs_extlen_t, 1, minlen / mp->m_sb.sb_rextsize);
+	error = xfs_rtallocate_extent(ap->tp, ap->blkno, raminlen, ap->length,
+			&ralen, ap->wasdel, prod, &rtb);
 	if (error)
 		return error;
 
-	ap->blkno = rtb;
-	if (ap->blkno != NULLFSBLOCK) {
-		ap->blkno *= mp->m_sb.sb_rextsize;
-		ralen *= mp->m_sb.sb_rextsize;
-		ap->length = ralen;
-		ap->ip->i_nblocks += ralen;
+	if (rtb != NULLRTBLOCK) {
+		ap->blkno = rtb * mp->m_sb.sb_rextsize;
+		ap->length = ralen * mp->m_sb.sb_rextsize;
+		ap->ip->i_nblocks += ap->length;
 		xfs_trans_log_inode(ap->tp, ap->ip, XFS_ILOG_CORE);
 		if (ap->wasdel)
-			ap->ip->i_delayed_blks -= ralen;
+			ap->ip->i_delayed_blks -= ap->length;
 		/*
 		 * Adjust the disk quota also. This was reserved
 		 * earlier.
 		 */
 		xfs_trans_mod_dquot_byino(ap->tp, ap->ip,
 			ap->wasdel ? XFS_TRANS_DQ_DELRTBCOUNT :
-					XFS_TRANS_DQ_RTBCOUNT, (long) ralen);
-	} else {
-		ap->length = 0;
+					XFS_TRANS_DQ_RTBCOUNT, ap->length);
+		return 0;
 	}
+
+	if (align > mp->m_sb.sb_rextsize) {
+		/*
+		 * We previously enlarged the request length to try to satisfy
+		 * an extent size hint.  The allocator didn't return anything,
+		 * so reset the parameters to the original values and try again
+		 * without alignment criteria.
+		 */
+		ap->offset = orig_offset;
+		ap->length = orig_length;
+		minlen = align = mp->m_sb.sb_rextsize;
+		goto retry;
+	}
+
+	ap->blkno = NULLFSBLOCK;
+	ap->length = 0;
 	return 0;
 }
 #endif /* CONFIG_XFS_RT */