jfs: define xtree root and page independently

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>

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: */

fs/jfs/jfs_imap.c

@@ -670,7 +670,7 @@ 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;
@@ -684,7 +684,7 @@ 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],
@@ -713,7 +713,7 @@ 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;
 
 		/*

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 {

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);
 		}
@@ -1676,7 +1676,7 @@ 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);

fs/jfs/jfs_xtree.c

@@ -1213,7 +1213,7 @@ 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);
 
@@ -2098,7 +2098,7 @@ int xtAppend(tid_t tid,		/* transaction id */
  */
 void xtInitRoot(tid_t tid, struct inode *ip)
 {
-	xtpage_t *p;
+	xtroot_t *p;
 
 	/*
 	 * acquire a transaction lock on the root

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;
 
 /*