diff --git a/fs/xfs/linux-2.6/xfs_ioctl.c b/fs/xfs/linux-2.6/xfs_ioctl.c
index 10206be..2ea238f6 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl.c
@@ -790,7 +790,7 @@
 	xfs_ilock(ip, XFS_ILOCK_SHARED);
 	fa.fsx_xflags = xfs_ip2xflags(ip);
 	fa.fsx_extsize = ip->i_d.di_extsize << ip->i_mount->m_sb.sb_blocklog;
-	fa.fsx_projid = ip->i_d.di_projid;
+	fa.fsx_projid = xfs_get_projid(ip);
 
 	if (attr) {
 		if (ip->i_afp) {
@@ -909,10 +909,10 @@
 		return XFS_ERROR(EIO);
 
 	/*
-	 * Disallow 32bit project ids because on-disk structure
-	 * is 16bit only.
+	 * Disallow 32bit project ids when projid32bit feature is not enabled.
 	 */
-	if ((mask & FSX_PROJID) && (fa->fsx_projid > (__uint16_t)-1))
+	if ((mask & FSX_PROJID) && (fa->fsx_projid > (__uint16_t)-1) &&
+			!xfs_sb_version_hasprojid32bit(&ip->i_mount->m_sb))
 		return XFS_ERROR(EINVAL);
 
 	/*
@@ -961,7 +961,7 @@
 	if (mask & FSX_PROJID) {
 		if (XFS_IS_QUOTA_RUNNING(mp) &&
 		    XFS_IS_PQUOTA_ON(mp) &&
-		    ip->i_d.di_projid != fa->fsx_projid) {
+		    xfs_get_projid(ip) != fa->fsx_projid) {
 			ASSERT(tp);
 			code = xfs_qm_vop_chown_reserve(tp, ip, udqp, gdqp,
 						capable(CAP_FOWNER) ?
@@ -1063,12 +1063,12 @@
 		 * Change the ownerships and register quota modifications
 		 * in the transaction.
 		 */
-		if (ip->i_d.di_projid != fa->fsx_projid) {
+		if (xfs_get_projid(ip) != fa->fsx_projid) {
 			if (XFS_IS_QUOTA_RUNNING(mp) && XFS_IS_PQUOTA_ON(mp)) {
 				olddquot = xfs_qm_vop_chown(tp, ip,
 							&ip->i_gdquot, gdqp);
 			}
-			ip->i_d.di_projid = fa->fsx_projid;
+			xfs_set_projid(ip, fa->fsx_projid);
 
 			/*
 			 * We may have to rev the inode as well as
diff --git a/fs/xfs/linux-2.6/xfs_ioctl32.c b/fs/xfs/linux-2.6/xfs_ioctl32.c
index 464bcc7..b3486df 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl32.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl32.c
@@ -164,7 +164,8 @@
 	    get_user(bstat->bs_extsize,	&bstat32->bs_extsize)	||
 	    get_user(bstat->bs_extents,	&bstat32->bs_extents)	||
 	    get_user(bstat->bs_gen,	&bstat32->bs_gen)	||
-	    get_user(bstat->bs_projid,	&bstat32->bs_projid)	||
+	    get_user(bstat->bs_projid_lo, &bstat32->bs_projid_lo) ||
+	    get_user(bstat->bs_projid_hi, &bstat32->bs_projid_hi) ||
 	    get_user(bstat->bs_dmevmask, &bstat32->bs_dmevmask)	||
 	    get_user(bstat->bs_dmstate,	&bstat32->bs_dmstate)	||
 	    get_user(bstat->bs_aextents, &bstat32->bs_aextents))
@@ -218,6 +219,7 @@
 	    put_user(buffer->bs_extents,  &p32->bs_extents)	||
 	    put_user(buffer->bs_gen,	  &p32->bs_gen)		||
 	    put_user(buffer->bs_projid,	  &p32->bs_projid)	||
+	    put_user(buffer->bs_projid_hi,	&p32->bs_projid_hi)	||
 	    put_user(buffer->bs_dmevmask, &p32->bs_dmevmask)	||
 	    put_user(buffer->bs_dmstate,  &p32->bs_dmstate)	||
 	    put_user(buffer->bs_aextents, &p32->bs_aextents))
diff --git a/fs/xfs/linux-2.6/xfs_ioctl32.h b/fs/xfs/linux-2.6/xfs_ioctl32.h
index 1024c4f..08b6057 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl32.h
+++ b/fs/xfs/linux-2.6/xfs_ioctl32.h
@@ -65,8 +65,10 @@
 	__s32		bs_extsize;	/* extent size			*/
 	__s32		bs_extents;	/* number of extents		*/
 	__u32		bs_gen;		/* generation count		*/
-	__u16		bs_projid;	/* project id			*/
-	unsigned char	bs_pad[14];	/* pad space, unused		*/
+	__u16		bs_projid_lo;	/* lower part of project id	*/
+#define	bs_projid	bs_projid_lo	/* (previously just bs_projid)	*/
+	__u16		bs_projid_hi;	/* high part of project id	*/
+	unsigned char	bs_pad[12];	/* pad space, unused		*/
 	__u32		bs_dmevmask;	/* DMIG event mask		*/
 	__u16		bs_dmstate;	/* DMIG state info		*/
 	__u16		bs_aextents;	/* attribute number of extents	*/
diff --git a/fs/xfs/linux-2.6/xfs_linux.h b/fs/xfs/linux-2.6/xfs_linux.h
index 76ebc58..214ddd7 100644
--- a/fs/xfs/linux-2.6/xfs_linux.h
+++ b/fs/xfs/linux-2.6/xfs_linux.h
@@ -143,7 +143,7 @@
 #define SYNCHRONIZE()	barrier()
 #define __return_address __builtin_return_address(0)
 
-#define dfltprid	0
+#define XFS_PROJID_DEFAULT	0
 #define MAXPATHLEN	1024
 
 #define MIN(a,b)	(min(a,b))
diff --git a/fs/xfs/quota/xfs_qm.c b/fs/xfs/quota/xfs_qm.c
index d109cc5..f8e854b 100644
--- a/fs/xfs/quota/xfs_qm.c
+++ b/fs/xfs/quota/xfs_qm.c
@@ -835,7 +835,7 @@
 			xfs_qm_dqattach_one(ip, ip->i_d.di_gid, XFS_DQ_GROUP,
 						flags & XFS_QMOPT_DQALLOC,
 						ip->i_udquot, &ip->i_gdquot) :
-			xfs_qm_dqattach_one(ip, ip->i_d.di_projid, XFS_DQ_PROJ,
+			xfs_qm_dqattach_one(ip, xfs_get_projid(ip), XFS_DQ_PROJ,
 						flags & XFS_QMOPT_DQALLOC,
 						ip->i_udquot, &ip->i_gdquot);
 		/*
@@ -1630,7 +1630,7 @@
 	}
 
 	if (XFS_IS_PQUOTA_ON(mp)) {
-		error = xfs_qm_quotacheck_dqadjust(ip, ip->i_d.di_projid,
+		error = xfs_qm_quotacheck_dqadjust(ip, xfs_get_projid(ip),
 						   XFS_DQ_PROJ, nblks, rtblks);
 		if (error)
 			goto error0;
@@ -2249,7 +2249,7 @@
 			xfs_dqunlock(gq);
 		}
 	} else if ((flags & XFS_QMOPT_PQUOTA) && XFS_IS_PQUOTA_ON(mp)) {
-		if (ip->i_d.di_projid != prid) {
+		if (xfs_get_projid(ip) != prid) {
 			xfs_iunlock(ip, lockflags);
 			if ((error = xfs_qm_dqget(mp, NULL, (xfs_dqid_t)prid,
 						 XFS_DQ_PROJ,
@@ -2371,7 +2371,7 @@
 	}
 	if (XFS_IS_OQUOTA_ON(ip->i_mount) && gdqp) {
 		if (XFS_IS_PQUOTA_ON(ip->i_mount) &&
-		     ip->i_d.di_projid != be32_to_cpu(gdqp->q_core.d_id))
+		     xfs_get_projid(ip) != be32_to_cpu(gdqp->q_core.d_id))
 			prjflags = XFS_QMOPT_ENOSPC;
 
 		if (prjflags ||
@@ -2475,7 +2475,7 @@
 		ip->i_gdquot = gdqp;
 		ASSERT(XFS_IS_OQUOTA_ON(mp));
 		ASSERT((XFS_IS_GQUOTA_ON(mp) ?
-			ip->i_d.di_gid : ip->i_d.di_projid) ==
+			ip->i_d.di_gid : xfs_get_projid(ip)) ==
 				be32_to_cpu(gdqp->q_core.d_id));
 		xfs_trans_mod_dquot(tp, gdqp, XFS_TRANS_DQ_ICOUNT, 1);
 	}
diff --git a/fs/xfs/quota/xfs_qm_bhv.c b/fs/xfs/quota/xfs_qm_bhv.c
index bea02d7..45b5cb1 100644
--- a/fs/xfs/quota/xfs_qm_bhv.c
+++ b/fs/xfs/quota/xfs_qm_bhv.c
@@ -81,7 +81,7 @@
 	xfs_mount_t		*mp = ip->i_mount;
 	xfs_dquot_t		*dqp;
 
-	if (!xfs_qm_dqget(mp, NULL, ip->i_d.di_projid, XFS_DQ_PROJ, 0, &dqp)) {
+	if (!xfs_qm_dqget(mp, NULL, xfs_get_projid(ip), XFS_DQ_PROJ, 0, &dqp)) {
 		xfs_fill_statvfs_from_dquot(statp, &dqp->q_core);
 		xfs_qm_dqput(dqp);
 	}
diff --git a/fs/xfs/quota/xfs_qm_syscalls.c b/fs/xfs/quota/xfs_qm_syscalls.c
index 5784743..bdebc18 100644
--- a/fs/xfs/quota/xfs_qm_syscalls.c
+++ b/fs/xfs/quota/xfs_qm_syscalls.c
@@ -1165,7 +1165,7 @@
 	}
 	xfs_qm_internalqcheck_get_dquots(mp,
 					(xfs_dqid_t) ip->i_d.di_uid,
-					(xfs_dqid_t) ip->i_d.di_projid,
+					(xfs_dqid_t) xfs_get_projid(ip),
 					(xfs_dqid_t) ip->i_d.di_gid,
 					&ud, &gd);
 	if (XFS_IS_UQUOTA_ON(mp)) {
diff --git a/fs/xfs/xfs_dinode.h b/fs/xfs/xfs_dinode.h
index e5b153b..dffba9b 100644
--- a/fs/xfs/xfs_dinode.h
+++ b/fs/xfs/xfs_dinode.h
@@ -49,8 +49,9 @@
 	__be32		di_uid;		/* owner's user id */
 	__be32		di_gid;		/* owner's group id */
 	__be32		di_nlink;	/* number of links to file */
-	__be16		di_projid;	/* owner's project id */
-	__u8		di_pad[8];	/* unused, zeroed space */
+	__be16		di_projid_lo;	/* lower part of owner's project id */
+	__be16		di_projid_hi;	/* higher part owner's project id */
+	__u8		di_pad[6];	/* unused, zeroed space */
 	__be16		di_flushiter;	/* incremented on flush */
 	xfs_timestamp_t	di_atime;	/* time last accessed */
 	xfs_timestamp_t	di_mtime;	/* time last modified */
diff --git a/fs/xfs/xfs_fs.h b/fs/xfs/xfs_fs.h
index 10f6093..8f6fc1a 100644
--- a/fs/xfs/xfs_fs.h
+++ b/fs/xfs/xfs_fs.h
@@ -293,9 +293,11 @@
 	__s32		bs_extsize;	/* extent size			*/
 	__s32		bs_extents;	/* number of extents		*/
 	__u32		bs_gen;		/* generation count		*/
-	__u16		bs_projid;	/* project id			*/
+	__u16		bs_projid_lo;	/* lower part of project id	*/
+#define	bs_projid	bs_projid_lo	/* (previously just bs_projid)	*/
 	__u16		bs_forkoff;	/* inode fork offset in bytes	*/
-	unsigned char	bs_pad[12];	/* pad space, unused		*/
+	__u16		bs_projid_hi;	/* higher part of project id	*/
+	unsigned char	bs_pad[10];	/* pad space, unused		*/
 	__u32		bs_dmevmask;	/* DMIG event mask		*/
 	__u16		bs_dmstate;	/* DMIG state info		*/
 	__u16		bs_aextents;	/* attribute number of extents	*/
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 493d6b0..108c7a0 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -660,7 +660,8 @@
 	to->di_uid = be32_to_cpu(from->di_uid);
 	to->di_gid = be32_to_cpu(from->di_gid);
 	to->di_nlink = be32_to_cpu(from->di_nlink);
-	to->di_projid = be16_to_cpu(from->di_projid);
+	to->di_projid_lo = be16_to_cpu(from->di_projid_lo);
+	to->di_projid_hi = be16_to_cpu(from->di_projid_hi);
 	memcpy(to->di_pad, from->di_pad, sizeof(to->di_pad));
 	to->di_flushiter = be16_to_cpu(from->di_flushiter);
 	to->di_atime.t_sec = be32_to_cpu(from->di_atime.t_sec);
@@ -695,7 +696,8 @@
 	to->di_uid = cpu_to_be32(from->di_uid);
 	to->di_gid = cpu_to_be32(from->di_gid);
 	to->di_nlink = cpu_to_be32(from->di_nlink);
-	to->di_projid = cpu_to_be16(from->di_projid);
+	to->di_projid_lo = cpu_to_be16(from->di_projid_lo);
+	to->di_projid_hi = cpu_to_be16(from->di_projid_hi);
 	memcpy(to->di_pad, from->di_pad, sizeof(to->di_pad));
 	to->di_flushiter = cpu_to_be16(from->di_flushiter);
 	to->di_atime.t_sec = cpu_to_be32(from->di_atime.t_sec);
@@ -874,7 +876,7 @@
 	if (ip->i_d.di_version == 1) {
 		ip->i_d.di_nlink = ip->i_d.di_onlink;
 		ip->i_d.di_onlink = 0;
-		ip->i_d.di_projid = 0;
+		xfs_set_projid(ip, 0);
 	}
 
 	ip->i_delayed_blks = 0;
@@ -982,7 +984,7 @@
 	mode_t		mode,
 	xfs_nlink_t	nlink,
 	xfs_dev_t	rdev,
-	xfs_prid_t	prid,
+	prid_t		prid,
 	int		okalloc,
 	xfs_buf_t	**ialloc_context,
 	boolean_t	*call_again,
@@ -1026,7 +1028,7 @@
 	ASSERT(ip->i_d.di_nlink == nlink);
 	ip->i_d.di_uid = current_fsuid();
 	ip->i_d.di_gid = current_fsgid();
-	ip->i_d.di_projid = prid;
+	xfs_set_projid(ip, prid);
 	memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));
 
 	/*
@@ -3007,7 +3009,7 @@
 			memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));
 			memset(&(dip->di_pad[0]), 0,
 			      sizeof(dip->di_pad));
-			ASSERT(ip->i_d.di_projid == 0);
+			ASSERT(xfs_get_projid(ip) == 0);
 		}
 	}
 
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index ac82327..fac5229 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -134,8 +134,9 @@
 	__uint32_t	di_uid;		/* owner's user id */
 	__uint32_t	di_gid;		/* owner's group id */
 	__uint32_t	di_nlink;	/* number of links to file */
-	__uint16_t	di_projid;	/* owner's project id */
-	__uint8_t	di_pad[8];	/* unused, zeroed space */
+	__uint16_t	di_projid_lo;	/* lower part of owner's project id */
+	__uint16_t	di_projid_hi;	/* higher part of owner's project id */
+	__uint8_t	di_pad[6];	/* unused, zeroed space */
 	__uint16_t	di_flushiter;	/* incremented on flush */
 	xfs_ictimestamp_t di_atime;	/* time last accessed */
 	xfs_ictimestamp_t di_mtime;	/* time last modified */
@@ -334,6 +335,25 @@
 }
 
 /*
+ * Project quota id helpers (previously projid was 16bit only
+ * and using two 16bit values to hold new 32bit projid was choosen
+ * to retain compatibility with "old" filesystems).
+ */
+static inline prid_t
+xfs_get_projid(struct xfs_inode *ip)
+{
+	return (prid_t)ip->i_d.di_projid_hi << 16 | ip->i_d.di_projid_lo;
+}
+
+static inline void
+xfs_set_projid(struct xfs_inode *ip,
+		prid_t projid)
+{
+	ip->i_d.di_projid_hi = (__uint16_t) (projid >> 16);
+	ip->i_d.di_projid_lo = (__uint16_t) (projid & 0xffff);
+}
+
+/*
  * Manage the i_flush queue embedded in the inode.  This completion
  * queue synchronizes processes attempting to flush the in-core
  * inode back to disk.
@@ -455,7 +475,7 @@
  * xfs_inode.c prototypes.
  */
 int		xfs_ialloc(struct xfs_trans *, xfs_inode_t *, mode_t,
-			   xfs_nlink_t, xfs_dev_t, xfs_prid_t, int,
+			   xfs_nlink_t, xfs_dev_t, prid_t, int,
 			   struct xfs_buf **, boolean_t *, xfs_inode_t **);
 
 uint		xfs_ip2xflags(struct xfs_inode *);
diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index 7e3626e..dc1882a 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -92,7 +92,8 @@
 	 * further change.
 	 */
 	buf->bs_nlink = dic->di_nlink;
-	buf->bs_projid = dic->di_projid;
+	buf->bs_projid_lo = dic->di_projid_lo;
+	buf->bs_projid_hi = dic->di_projid_hi;
 	buf->bs_ino = ino;
 	buf->bs_mode = dic->di_mode;
 	buf->bs_uid = dic->di_uid;
diff --git a/fs/xfs/xfs_rename.c b/fs/xfs/xfs_rename.c
index 9028733..d2af0a8 100644
--- a/fs/xfs/xfs_rename.c
+++ b/fs/xfs/xfs_rename.c
@@ -183,7 +183,7 @@
 	 * tree quota mechanism would be circumvented.
 	 */
 	if (unlikely((target_dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) &&
-		     (target_dp->i_d.di_projid != src_ip->i_d.di_projid))) {
+		     (xfs_get_projid(target_dp) != xfs_get_projid(src_ip)))) {
 		error = XFS_ERROR(EXDEV);
 		goto error_return;
 	}
diff --git a/fs/xfs/xfs_sb.h b/fs/xfs/xfs_sb.h
index 1b017c6..1eb2ba5 100644
--- a/fs/xfs/xfs_sb.h
+++ b/fs/xfs/xfs_sb.h
@@ -80,10 +80,12 @@
 #define XFS_SB_VERSION2_RESERVED4BIT	0x00000004
 #define XFS_SB_VERSION2_ATTR2BIT	0x00000008	/* Inline attr rework */
 #define XFS_SB_VERSION2_PARENTBIT	0x00000010	/* parent pointers */
+#define XFS_SB_VERSION2_PROJID32BIT	0x00000080	/* 32 bit project id */
 
 #define	XFS_SB_VERSION2_OKREALFBITS	\
 	(XFS_SB_VERSION2_LAZYSBCOUNTBIT	| \
-	 XFS_SB_VERSION2_ATTR2BIT)
+	 XFS_SB_VERSION2_ATTR2BIT	| \
+	 XFS_SB_VERSION2_PROJID32BIT)
 #define	XFS_SB_VERSION2_OKSASHFBITS	\
 	(0)
 #define XFS_SB_VERSION2_OKREALBITS	\
@@ -495,6 +497,12 @@
 		sbp->sb_versionnum &= ~XFS_SB_VERSION_MOREBITSBIT;
 }
 
+static inline int xfs_sb_version_hasprojid32bit(xfs_sb_t *sbp)
+{
+	return xfs_sb_version_hasmorebits(sbp) &&
+		(sbp->sb_features2 & XFS_SB_VERSION2_PROJID32BIT);
+}
+
 /*
  * end of superblock version macros
  */
diff --git a/fs/xfs/xfs_types.h b/fs/xfs/xfs_types.h
index 3207752..26d1867 100644
--- a/fs/xfs/xfs_types.h
+++ b/fs/xfs/xfs_types.h
@@ -73,8 +73,6 @@
 typedef	__uint32_t	xfs_dablk_t;	/* dir/attr block number (in file) */
 typedef	__uint32_t	xfs_dahash_t;	/* dir/attr hash value */
 
-typedef __uint16_t	xfs_prid_t;	/* prid_t truncated to 16bits in XFS */
-
 typedef __uint32_t	xlog_tid_t;	/* transaction ID type */
 
 /*
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index f4195f6..8e4a63c 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -114,7 +114,7 @@
 		 */
 		ASSERT(udqp == NULL);
 		ASSERT(gdqp == NULL);
-		code = xfs_qm_vop_dqalloc(ip, uid, gid, ip->i_d.di_projid,
+		code = xfs_qm_vop_dqalloc(ip, uid, gid, xfs_get_projid(ip),
 					 qflags, &udqp, &gdqp);
 		if (code)
 			return code;
@@ -1268,7 +1268,7 @@
 	boolean_t		unlock_dp_on_error = B_FALSE;
 	uint			cancel_flags;
 	int			committed;
-	xfs_prid_t		prid;
+	prid_t			prid;
 	struct xfs_dquot	*udqp = NULL;
 	struct xfs_dquot	*gdqp = NULL;
 	uint			resblks;
@@ -1281,9 +1281,9 @@
 		return XFS_ERROR(EIO);
 
 	if (dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
-		prid = dp->i_d.di_projid;
+		prid = xfs_get_projid(dp);
 	else
-		prid = dfltprid;
+		prid = XFS_PROJID_DEFAULT;
 
 	/*
 	 * Make sure that we have allocated dquot(s) on disk.
@@ -1882,7 +1882,7 @@
 	 * the tree quota mechanism could be circumvented.
 	 */
 	if (unlikely((tdp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) &&
-		     (tdp->i_d.di_projid != sip->i_d.di_projid))) {
+		     (xfs_get_projid(tdp) != xfs_get_projid(sip)))) {
 		error = XFS_ERROR(EXDEV);
 		goto error_return;
 	}
@@ -1956,7 +1956,7 @@
 	int			byte_cnt;
 	int			n;
 	xfs_buf_t		*bp;
-	xfs_prid_t		prid;
+	prid_t			prid;
 	struct xfs_dquot	*udqp, *gdqp;
 	uint			resblks;
 
@@ -1979,9 +1979,9 @@
 
 	udqp = gdqp = NULL;
 	if (dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
-		prid = dp->i_d.di_projid;
+		prid = xfs_get_projid(dp);
 	else
-		prid = (xfs_prid_t)dfltprid;
+		prid = XFS_PROJID_DEFAULT;
 
 	/*
 	 * Make sure that we have allocated dquot(s) on disk.