[PATCH 5.15.y] jfs: define xtree root and page independently

[PATCH 5.15.y] jfs: define xtree root and page independently

[Aditya Dutt]

From: Dave Kleikamp <dave.kleikamp@oracle.com>

[ Upstream commit a779ed754e52d582b8c0e17959df063108bd0656 ]

In order to make array bounds checking sane, provide a separate
definition of the in-inode xtree root and the external xtree page.

Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Tested-by: Manas Ghandat <ghandatmanas@gmail.com>
(cherry picked from commit a779ed754e52d582b8c0e17959df063108bd0656)
Closes: https://syzkaller.appspot.com/bug?extid=ccb458b6679845ee0bae
Signed-off-by: Aditya Dutt <duttaditya18@gmail.com>
---
Tested using C reproducer here: https://syzkaller.appspot.com/x/repro.c?x=113bb250e80000
(given in the dashboard link above
UBSAN is not triggered when this commit is there.
It is triggered when it is not.

 fs/jfs/jfs_dinode.h |  2 +-
 fs/jfs/jfs_imap.c   |  6 +++---
 fs/jfs/jfs_incore.h |  2 +-
 fs/jfs/jfs_txnmgr.c |  4 ++--
 fs/jfs/jfs_xtree.c  |  4 ++--
 fs/jfs/jfs_xtree.h  | 37 +++++++++++++++++++++++--------------
 6 files changed, 32 insertions(+), 23 deletions(-)

diff --git a/fs/jfs/jfs_dinode.h b/fs/jfs/jfs_dinode.h
index 5fa9fd594115..e630810a48c6 100644
--- a/fs/jfs/jfs_dinode.h
+++ b/fs/jfs/jfs_dinode.h
@@ -96,7 +96,7 @@ struct dinode {
 #define di_gengen	u._file._u1._imap._gengen
 
 			union {
-				xtpage_t _xtroot;
+				xtroot_t _xtroot;
 				struct {
 					u8 unused[16];	/* 16: */
 					dxd_t _dxd;	/* 16: */
diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
index 937ca07b58b1..5a360cd54098 100644
--- a/fs/jfs/jfs_imap.c
+++ b/fs/jfs/jfs_imap.c
@@ -671,7 +671,7 @@ int diWrite(tid_t tid, struct inode *ip)
 		 * This is the special xtree inside the directory for storing
 		 * the directory table
 		 */
-		xtpage_t *p, *xp;
+		xtroot_t *p, *xp;
 		xad_t *xad;
 
 		jfs_ip->xtlid = 0;
@@ -685,7 +685,7 @@ int diWrite(tid_t tid, struct inode *ip)
 		 * copy xtree root from inode to dinode:
 		 */
 		p = &jfs_ip->i_xtroot;
-		xp = (xtpage_t *) &dp->di_dirtable;
+		xp = (xtroot_t *) &dp->di_dirtable;
 		lv = ilinelock->lv;
 		for (n = 0; n < ilinelock->index; n++, lv++) {
 			memcpy(&xp->xad[lv->offset], &p->xad[lv->offset],
@@ -714,7 +714,7 @@ int diWrite(tid_t tid, struct inode *ip)
 	 *	regular file: 16 byte (XAD slot) granularity
 	 */
 	if (type & tlckXTREE) {
-		xtpage_t *p, *xp;
+		xtroot_t *p, *xp;
 		xad_t *xad;
 
 		/*
diff --git a/fs/jfs/jfs_incore.h b/fs/jfs/jfs_incore.h
index a466ec41cfbb..852f4c1f2946 100644
--- a/fs/jfs/jfs_incore.h
+++ b/fs/jfs/jfs_incore.h
@@ -66,7 +66,7 @@ struct jfs_inode_info {
 	lid_t	xtlid;		/* lid of xtree lock on directory */
 	union {
 		struct {
-			xtpage_t _xtroot;	/* 288: xtree root */
+			xtroot_t _xtroot;	/* 288: xtree root */
 			struct inomap *_imap;	/* 4: inode map header	*/
 		} file;
 		struct {
diff --git a/fs/jfs/jfs_txnmgr.c b/fs/jfs/jfs_txnmgr.c
index dca8edd2378c..7d19324f5a83 100644
--- a/fs/jfs/jfs_txnmgr.c
+++ b/fs/jfs/jfs_txnmgr.c
@@ -778,7 +778,7 @@ struct tlock *txLock(tid_t tid, struct inode *ip, struct metapage * mp,
 			if (mp->xflag & COMMIT_PAGE)
 				p = (xtpage_t *) mp->data;
 			else
-				p = &jfs_ip->i_xtroot;
+				p = (xtpage_t *) &jfs_ip->i_xtroot;
 			xtlck->lwm.offset =
 			    le16_to_cpu(p->header.nextindex);
 		}
@@ -1708,7 +1708,7 @@ static void xtLog(struct jfs_log * log, struct tblock * tblk, struct lrd * lrd,
 
 	if (tlck->type & tlckBTROOT) {
 		lrd->log.redopage.type |= cpu_to_le16(LOG_BTROOT);
-		p = &JFS_IP(ip)->i_xtroot;
+		p = (xtpage_t *) &JFS_IP(ip)->i_xtroot;
 		if (S_ISDIR(ip->i_mode))
 			lrd->log.redopage.type |=
 			    cpu_to_le16(LOG_DIR_XTREE);
diff --git a/fs/jfs/jfs_xtree.c b/fs/jfs/jfs_xtree.c
index 3148e9b35f3b..34db519933b4 100644
--- a/fs/jfs/jfs_xtree.c
+++ b/fs/jfs/jfs_xtree.c
@@ -1224,7 +1224,7 @@ xtSplitRoot(tid_t tid,
 	struct xtlock *xtlck;
 	int rc;
 
-	sp = &JFS_IP(ip)->i_xtroot;
+	sp = (xtpage_t *) &JFS_IP(ip)->i_xtroot;
 
 	INCREMENT(xtStat.split);
 
@@ -3059,7 +3059,7 @@ static int xtRelink(tid_t tid, struct inode *ip, xtpage_t * p)
  */
 void xtInitRoot(tid_t tid, struct inode *ip)
 {
-	xtpage_t *p;
+	xtroot_t *p;
 
 	/*
 	 * acquire a transaction lock on the root
diff --git a/fs/jfs/jfs_xtree.h b/fs/jfs/jfs_xtree.h
index 5f51be8596b3..dc9b5f8d6385 100644
--- a/fs/jfs/jfs_xtree.h
+++ b/fs/jfs/jfs_xtree.h
@@ -65,24 +65,33 @@ struct xadlist {
 #define XTPAGEMAXSLOT	256
 #define XTENTRYSTART	2
 
-/*
- *	xtree page:
- */
-typedef union {
-	struct xtheader {
-		__le64 next;	/* 8: */
-		__le64 prev;	/* 8: */
+struct xtheader {
+	__le64 next;	/* 8: */
+	__le64 prev;	/* 8: */
 
-		u8 flag;	/* 1: */
-		u8 rsrvd1;	/* 1: */
-		__le16 nextindex;	/* 2: next index = number of entries */
-		__le16 maxentry;	/* 2: max number of entries */
-		__le16 rsrvd2;	/* 2: */
+	u8 flag;	/* 1: */
+	u8 rsrvd1;	/* 1: */
+	__le16 nextindex;	/* 2: next index = number of entries */
+	__le16 maxentry;	/* 2: max number of entries */
+	__le16 rsrvd2;	/* 2: */
 
-		pxd_t self;	/* 8: self */
-	} header;		/* (32) */
+	pxd_t self;	/* 8: self */
+};
 
+/*
+ *	xtree root (in inode):
+ */
+typedef union {
+	struct xtheader header;
 	xad_t xad[XTROOTMAXSLOT];	/* 16 * maxentry: xad array */
+} xtroot_t;
+
+/*
+ *	xtree page:
+ */
+typedef union {
+	struct xtheader header;
+	xad_t xad[XTPAGEMAXSLOT];	/* 16 * maxentry: xad array */
 } xtpage_t;
 
 /*
-- 
2.34.1

Re: [PATCH 5.15.y] jfs: define xtree root and page independently

[Aditya Dutt]

syzbot checked the patch against 5.15.y and confirmed that the
reproducer did not trigger any issues. check here:
https://lore.kernel.org/lkml/67fea0bf.050a0220.186b78.0006.GAE@google.com/

Re: [PATCH 5.15.y] jfs: define xtree root and page independently

[Greg KH]

On Tue, Apr 15, 2025 at 11:39:39PM +0530, Aditya Dutt wrote:
> From: Dave Kleikamp <dave.kleikamp@oracle.com>
> 
> [ Upstream commit a779ed754e52d582b8c0e17959df063108bd0656 ]
> 
> In order to make array bounds checking sane, provide a separate
> definition of the in-inode xtree root and the external xtree page.
> 
> Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
> Tested-by: Manas Ghandat <ghandatmanas@gmail.com>
> (cherry picked from commit a779ed754e52d582b8c0e17959df063108bd0656)
> Closes: https://syzkaller.appspot.com/bug?extid=ccb458b6679845ee0bae
> Signed-off-by: Aditya Dutt <duttaditya18@gmail.com>
> ---
> Tested using C reproducer here: https://syzkaller.appspot.com/x/repro.c?x=113bb250e80000
> (given in the dashboard link above
> UBSAN is not triggered when this commit is there.
> It is triggered when it is not.

Please always submit backports for all relevant stable trees.  We can't
take this one until the newer trees are fixed.

Please resubmit all ones needed.

thanks,

greg k-h

[PATCH 5.15.y] jfs: define xtree root and page independently

[Aditya Dutt]

From: Dave Kleikamp <dave.kleikamp@oracle.com>

[ Upstream commit a779ed754e52d582b8c0e17959df063108bd0656 ]

In order to make array bounds checking sane, provide a separate
definition of the in-inode xtree root and the external xtree page.

Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Tested-by: Manas Ghandat <ghandatmanas@gmail.com>
(cherry picked from commit a779ed754e52d582b8c0e17959df063108bd0656)
Closes: https://syzkaller.appspot.com/bug?extid=ccb458b6679845ee0bae
Reported-by: syzbot+ccb458b6679845ee0bae@syzkaller.appspotmail.com
Signed-off-by: Aditya Dutt <duttaditya18@gmail.com>
---
I am sending this as per the suggestion by Greg to submit backports for
all the relevant stable trees:
https://lore.kernel.org/stable/2025042210-stylized-nearest-ea59@gregkh/
This patch has been applied in >= 6.12
and has been backported to 6.6: 2ff51719ec615e1b373c1811443efe93594c41a9
I have already sent a mail for 6.1:
https://lore.kernel.org/stable/20250427153045.90396-1-duttaditya18@gmail.com/

syzbot checked the patch against 5.15.y and confirmed that the
reproducer did not trigger any issues. check here:
https://lore.kernel.org/lkml/67fea0bf.050a0220.186b78.0006.GAE@google.com/

 fs/jfs/jfs_dinode.h |  2 +-
 fs/jfs/jfs_imap.c   |  6 +++---
 fs/jfs/jfs_incore.h |  2 +-
 fs/jfs/jfs_txnmgr.c |  4 ++--
 fs/jfs/jfs_xtree.c  |  4 ++--
 fs/jfs/jfs_xtree.h  | 37 +++++++++++++++++++++++--------------
 6 files changed, 32 insertions(+), 23 deletions(-)

diff --git a/fs/jfs/jfs_dinode.h b/fs/jfs/jfs_dinode.h
index 6b231d0d0071..603aae17a693 100644
--- a/fs/jfs/jfs_dinode.h
+++ b/fs/jfs/jfs_dinode.h
@@ -96,7 +96,7 @@ struct dinode {
 #define di_gengen	u._file._u1._imap._gengen
 
 			union {
-				xtpage_t _xtroot;
+				xtroot_t _xtroot;
 				struct {
 					u8 unused[16];	/* 16: */
 					dxd_t _dxd;	/* 16: */
diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
index c72e97f06579..0e7d2662f202 100644
--- a/fs/jfs/jfs_imap.c
+++ b/fs/jfs/jfs_imap.c
@@ -673,7 +673,7 @@ int diWrite(tid_t tid, struct inode *ip)
 		 * This is the special xtree inside the directory for storing
 		 * the directory table
 		 */
-		xtpage_t *p, *xp;
+		xtroot_t *p, *xp;
 		xad_t *xad;
 
 		jfs_ip->xtlid = 0;
@@ -687,7 +687,7 @@ int diWrite(tid_t tid, struct inode *ip)
 		 * copy xtree root from inode to dinode:
 		 */
 		p = &jfs_ip->i_xtroot;
-		xp = (xtpage_t *) &dp->di_dirtable;
+		xp = (xtroot_t *) &dp->di_dirtable;
 		lv = ilinelock->lv;
 		for (n = 0; n < ilinelock->index; n++, lv++) {
 			memcpy(&xp->xad[lv->offset], &p->xad[lv->offset],
@@ -716,7 +716,7 @@ int diWrite(tid_t tid, struct inode *ip)
 	 *	regular file: 16 byte (XAD slot) granularity
 	 */
 	if (type & tlckXTREE) {
-		xtpage_t *p, *xp;
+		xtroot_t *p, *xp;
 		xad_t *xad;
 
 		/*
diff --git a/fs/jfs/jfs_incore.h b/fs/jfs/jfs_incore.h
index 721def69e732..dd4264aa9bed 100644
--- a/fs/jfs/jfs_incore.h
+++ b/fs/jfs/jfs_incore.h
@@ -66,7 +66,7 @@ struct jfs_inode_info {
 	lid_t	xtlid;		/* lid of xtree lock on directory */
 	union {
 		struct {
-			xtpage_t _xtroot;	/* 288: xtree root */
+			xtroot_t _xtroot;	/* 288: xtree root */
 			struct inomap *_imap;	/* 4: inode map header	*/
 		} file;
 		struct {
diff --git a/fs/jfs/jfs_txnmgr.c b/fs/jfs/jfs_txnmgr.c
index 6c8680d3907a..3a547e0b934f 100644
--- a/fs/jfs/jfs_txnmgr.c
+++ b/fs/jfs/jfs_txnmgr.c
@@ -783,7 +783,7 @@ struct tlock *txLock(tid_t tid, struct inode *ip, struct metapage * mp,
 			if (mp->xflag & COMMIT_PAGE)
 				p = (xtpage_t *) mp->data;
 			else
-				p = &jfs_ip->i_xtroot;
+				p = (xtpage_t *) &jfs_ip->i_xtroot;
 			xtlck->lwm.offset =
 			    le16_to_cpu(p->header.nextindex);
 		}
@@ -1710,7 +1710,7 @@ static void xtLog(struct jfs_log * log, struct tblock * tblk, struct lrd * lrd,
 
 	if (tlck->type & tlckBTROOT) {
 		lrd->log.redopage.type |= cpu_to_le16(LOG_BTROOT);
-		p = &JFS_IP(ip)->i_xtroot;
+		p = (xtpage_t *) &JFS_IP(ip)->i_xtroot;
 		if (S_ISDIR(ip->i_mode))
 			lrd->log.redopage.type |=
 			    cpu_to_le16(LOG_DIR_XTREE);
diff --git a/fs/jfs/jfs_xtree.c b/fs/jfs/jfs_xtree.c
index 3148e9b35f3b..34db519933b4 100644
--- a/fs/jfs/jfs_xtree.c
+++ b/fs/jfs/jfs_xtree.c
@@ -1224,7 +1224,7 @@ xtSplitRoot(tid_t tid,
 	struct xtlock *xtlck;
 	int rc;
 
-	sp = &JFS_IP(ip)->i_xtroot;
+	sp = (xtpage_t *) &JFS_IP(ip)->i_xtroot;
 
 	INCREMENT(xtStat.split);
 
@@ -3059,7 +3059,7 @@ static int xtRelink(tid_t tid, struct inode *ip, xtpage_t * p)
  */
 void xtInitRoot(tid_t tid, struct inode *ip)
 {
-	xtpage_t *p;
+	xtroot_t *p;
 
 	/*
 	 * acquire a transaction lock on the root
diff --git a/fs/jfs/jfs_xtree.h b/fs/jfs/jfs_xtree.h
index 5f51be8596b3..dc9b5f8d6385 100644
--- a/fs/jfs/jfs_xtree.h
+++ b/fs/jfs/jfs_xtree.h
@@ -65,24 +65,33 @@ struct xadlist {
 #define XTPAGEMAXSLOT	256
 #define XTENTRYSTART	2
 
-/*
- *	xtree page:
- */
-typedef union {
-	struct xtheader {
-		__le64 next;	/* 8: */
-		__le64 prev;	/* 8: */
+struct xtheader {
+	__le64 next;	/* 8: */
+	__le64 prev;	/* 8: */
 
-		u8 flag;	/* 1: */
-		u8 rsrvd1;	/* 1: */
-		__le16 nextindex;	/* 2: next index = number of entries */
-		__le16 maxentry;	/* 2: max number of entries */
-		__le16 rsrvd2;	/* 2: */
+	u8 flag;	/* 1: */
+	u8 rsrvd1;	/* 1: */
+	__le16 nextindex;	/* 2: next index = number of entries */
+	__le16 maxentry;	/* 2: max number of entries */
+	__le16 rsrvd2;	/* 2: */
 
-		pxd_t self;	/* 8: self */
-	} header;		/* (32) */
+	pxd_t self;	/* 8: self */
+};
 
+/*
+ *	xtree root (in inode):
+ */
+typedef union {
+	struct xtheader header;
 	xad_t xad[XTROOTMAXSLOT];	/* 16 * maxentry: xad array */
+} xtroot_t;
+
+/*
+ *	xtree page:
+ */
+typedef union {
+	struct xtheader header;
+	xad_t xad[XTPAGEMAXSLOT];	/* 16 * maxentry: xad array */
 } xtpage_t;
 
 /*
-- 
2.34.1

[PATCH 5.15.y] jfs: define xtree root and page independently

[Aditya Dutt]

From: Dave Kleikamp <dave.kleikamp@oracle.com>

[ Upstream commit a779ed754e52d582b8c0e17959df063108bd0656 ]

In order to make array bounds checking sane, provide a separate
definition of the in-inode xtree root and the external xtree page.

Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Tested-by: Manas Ghandat <ghandatmanas@gmail.com>
(cherry picked from commit a779ed754e52d582b8c0e17959df063108bd0656)
Closes: https://syzkaller.appspot.com/bug?extid=ccb458b6679845ee0bae
Signed-off-by: Aditya Dutt <duttaditya18@gmail.com>
---
Tested using C reproducer here: https://syzkaller.appspot.com/x/repro.c?x=113bb250e80000
(given in the dashboard link above
UBSAN is not triggered when this commit is there.
It is triggered when it is not.

 fs/jfs/jfs_dinode.h |  2 +-
 fs/jfs/jfs_imap.c   |  6 +++---
 fs/jfs/jfs_incore.h |  2 +-
 fs/jfs/jfs_txnmgr.c |  4 ++--
 fs/jfs/jfs_xtree.c  |  4 ++--
 fs/jfs/jfs_xtree.h  | 37 +++++++++++++++++++++++--------------
 6 files changed, 32 insertions(+), 23 deletions(-)

diff --git a/fs/jfs/jfs_dinode.h b/fs/jfs/jfs_dinode.h
index 5fa9fd594115..e630810a48c6 100644
--- a/fs/jfs/jfs_dinode.h
+++ b/fs/jfs/jfs_dinode.h
@@ -96,7 +96,7 @@ struct dinode {
 #define di_gengen	u._file._u1._imap._gengen
 
 			union {
-				xtpage_t _xtroot;
+				xtroot_t _xtroot;
 				struct {
 					u8 unused[16];	/* 16: */
 					dxd_t _dxd;	/* 16: */
diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
index 937ca07b58b1..5a360cd54098 100644
--- a/fs/jfs/jfs_imap.c
+++ b/fs/jfs/jfs_imap.c
@@ -671,7 +671,7 @@ int diWrite(tid_t tid, struct inode *ip)
 		 * This is the special xtree inside the directory for storing
 		 * the directory table
 		 */
-		xtpage_t *p, *xp;
+		xtroot_t *p, *xp;
 		xad_t *xad;
 
 		jfs_ip->xtlid = 0;
@@ -685,7 +685,7 @@ int diWrite(tid_t tid, struct inode *ip)
 		 * copy xtree root from inode to dinode:
 		 */
 		p = &jfs_ip->i_xtroot;
-		xp = (xtpage_t *) &dp->di_dirtable;
+		xp = (xtroot_t *) &dp->di_dirtable;
 		lv = ilinelock->lv;
 		for (n = 0; n < ilinelock->index; n++, lv++) {
 			memcpy(&xp->xad[lv->offset], &p->xad[lv->offset],
@@ -714,7 +714,7 @@ int diWrite(tid_t tid, struct inode *ip)
 	 *	regular file: 16 byte (XAD slot) granularity
 	 */
 	if (type & tlckXTREE) {
-		xtpage_t *p, *xp;
+		xtroot_t *p, *xp;
 		xad_t *xad;
 
 		/*
diff --git a/fs/jfs/jfs_incore.h b/fs/jfs/jfs_incore.h
index a466ec41cfbb..852f4c1f2946 100644
--- a/fs/jfs/jfs_incore.h
+++ b/fs/jfs/jfs_incore.h
@@ -66,7 +66,7 @@ struct jfs_inode_info {
 	lid_t	xtlid;		/* lid of xtree lock on directory */
 	union {
 		struct {
-			xtpage_t _xtroot;	/* 288: xtree root */
+			xtroot_t _xtroot;	/* 288: xtree root */
 			struct inomap *_imap;	/* 4: inode map header	*/
 		} file;
 		struct {
diff --git a/fs/jfs/jfs_txnmgr.c b/fs/jfs/jfs_txnmgr.c
index dca8edd2378c..7d19324f5a83 100644
--- a/fs/jfs/jfs_txnmgr.c
+++ b/fs/jfs/jfs_txnmgr.c
@@ -778,7 +778,7 @@ struct tlock *txLock(tid_t tid, struct inode *ip, struct metapage * mp,
 			if (mp->xflag & COMMIT_PAGE)
 				p = (xtpage_t *) mp->data;
 			else
-				p = &jfs_ip->i_xtroot;
+				p = (xtpage_t *) &jfs_ip->i_xtroot;
 			xtlck->lwm.offset =
 			    le16_to_cpu(p->header.nextindex);
 		}
@@ -1708,7 +1708,7 @@ static void xtLog(struct jfs_log * log, struct tblock * tblk, struct lrd * lrd,
 
 	if (tlck->type & tlckBTROOT) {
 		lrd->log.redopage.type |= cpu_to_le16(LOG_BTROOT);
-		p = &JFS_IP(ip)->i_xtroot;
+		p = (xtpage_t *) &JFS_IP(ip)->i_xtroot;
 		if (S_ISDIR(ip->i_mode))
 			lrd->log.redopage.type |=
 			    cpu_to_le16(LOG_DIR_XTREE);
diff --git a/fs/jfs/jfs_xtree.c b/fs/jfs/jfs_xtree.c
index 3148e9b35f3b..34db519933b4 100644
--- a/fs/jfs/jfs_xtree.c
+++ b/fs/jfs/jfs_xtree.c
@@ -1224,7 +1224,7 @@ xtSplitRoot(tid_t tid,
 	struct xtlock *xtlck;
 	int rc;
 
-	sp = &JFS_IP(ip)->i_xtroot;
+	sp = (xtpage_t *) &JFS_IP(ip)->i_xtroot;
 
 	INCREMENT(xtStat.split);
 
@@ -3059,7 +3059,7 @@ static int xtRelink(tid_t tid, struct inode *ip, xtpage_t * p)
  */
 void xtInitRoot(tid_t tid, struct inode *ip)
 {
-	xtpage_t *p;
+	xtroot_t *p;
 
 	/*
 	 * acquire a transaction lock on the root
diff --git a/fs/jfs/jfs_xtree.h b/fs/jfs/jfs_xtree.h
index 5f51be8596b3..dc9b5f8d6385 100644
--- a/fs/jfs/jfs_xtree.h
+++ b/fs/jfs/jfs_xtree.h
@@ -65,24 +65,33 @@ struct xadlist {
 #define XTPAGEMAXSLOT	256
 #define XTENTRYSTART	2
 
-/*
- *	xtree page:
- */
-typedef union {
-	struct xtheader {
-		__le64 next;	/* 8: */
-		__le64 prev;	/* 8: */
+struct xtheader {
+	__le64 next;	/* 8: */
+	__le64 prev;	/* 8: */
 
-		u8 flag;	/* 1: */
-		u8 rsrvd1;	/* 1: */
-		__le16 nextindex;	/* 2: next index = number of entries */
-		__le16 maxentry;	/* 2: max number of entries */
-		__le16 rsrvd2;	/* 2: */
+	u8 flag;	/* 1: */
+	u8 rsrvd1;	/* 1: */
+	__le16 nextindex;	/* 2: next index = number of entries */
+	__le16 maxentry;	/* 2: max number of entries */
+	__le16 rsrvd2;	/* 2: */
 
-		pxd_t self;	/* 8: self */
-	} header;		/* (32) */
+	pxd_t self;	/* 8: self */
+};
 
+/*
+ *	xtree root (in inode):
+ */
+typedef union {
+	struct xtheader header;
 	xad_t xad[XTROOTMAXSLOT];	/* 16 * maxentry: xad array */
+} xtroot_t;
+
+/*
+ *	xtree page:
+ */
+typedef union {
+	struct xtheader header;
+	xad_t xad[XTPAGEMAXSLOT];	/* 16 * maxentry: xad array */
 } xtpage_t;
 
 /*
-- 
2.34.1