Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2916 insertions, 0 deletions

diff --git a/fs/jfs/jfs_xtree.c b/fs/jfs/jfs_xtree.c
new file mode 100644
index 000000000..2d304cee8
--- /dev/null
+++ b/fs/jfs/jfs_xtree.c
@@ -0,0 +1,2916 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *   Copyright (C) International Business Machines Corp., 2000-2005
+ */
+/*
+ *	jfs_xtree.c: extent allocation descriptor B+-tree manager
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/quotaops.h>
+#include <linux/seq_file.h>
+#include "jfs_incore.h"
+#include "jfs_filsys.h"
+#include "jfs_metapage.h"
+#include "jfs_dmap.h"
+#include "jfs_dinode.h"
+#include "jfs_superblock.h"
+#include "jfs_debug.h"
+
+/*
+ * xtree local flag
+ */
+#define XT_INSERT	0x00000001
+
+/*
+ *	xtree key/entry comparison: extent offset
+ *
+ * return:
+ *	-1: k < start of extent
+ *	 0: start_of_extent <= k <= end_of_extent
+ *	 1: k > end_of_extent
+ */
+#define XT_CMP(CMP, K, X, OFFSET64)\
+{\
+	OFFSET64 = offsetXAD(X);\
+	(CMP) = ((K) >= OFFSET64 + lengthXAD(X)) ? 1 :\
+		((K) < OFFSET64) ? -1 : 0;\
+}
+
+/* write a xad entry */
+#define XT_PUTENTRY(XAD, FLAG, OFF, LEN, ADDR)\
+{\
+	(XAD)->flag = (FLAG);\
+	XADoffset((XAD), (OFF));\
+	XADlength((XAD), (LEN));\
+	XADaddress((XAD), (ADDR));\
+}
+
+#define XT_PAGE(IP, MP) BT_PAGE(IP, MP, xtpage_t, i_xtroot)
+
+/* get page buffer for specified block address */
+/* ToDo: Replace this ugly macro with a function */
+#define XT_GETPAGE(IP, BN, MP, SIZE, P, RC)				\
+do {									\
+	BT_GETPAGE(IP, BN, MP, xtpage_t, SIZE, P, RC, i_xtroot);	\
+	if (!(RC)) {							\
+		if ((le16_to_cpu((P)->header.nextindex) < XTENTRYSTART) || \
+		    (le16_to_cpu((P)->header.nextindex) >		\
+		     le16_to_cpu((P)->header.maxentry)) ||		\
+		    (le16_to_cpu((P)->header.maxentry) >		\
+		     (((BN) == 0) ? XTROOTMAXSLOT : PSIZE >> L2XTSLOTSIZE))) { \
+			jfs_error((IP)->i_sb,				\
+				  "XT_GETPAGE: xtree page corrupt\n");	\
+			BT_PUTPAGE(MP);					\
+			MP = NULL;					\
+			RC = -EIO;					\
+		}							\
+	}								\
+} while (0)
+
+/* for consistency */
+#define XT_PUTPAGE(MP) BT_PUTPAGE(MP)
+
+#define XT_GETSEARCH(IP, LEAF, BN, MP, P, INDEX) \
+	BT_GETSEARCH(IP, LEAF, BN, MP, xtpage_t, P, INDEX, i_xtroot)
+/* xtree entry parameter descriptor */
+struct xtsplit {
+	struct metapage *mp;
+	s16 index;
+	u8 flag;
+	s64 off;
+	s64 addr;
+	int len;
+	struct pxdlist *pxdlist;
+};
+
+
+/*
+ *	statistics
+ */
+#ifdef CONFIG_JFS_STATISTICS
+static struct {
+	uint search;
+	uint fastSearch;
+	uint split;
+} xtStat;
+#endif
+
+
+/*
+ * forward references
+ */
+static int xtSearch(struct inode *ip, s64 xoff, s64 *next, int *cmpp,
+		    struct btstack * btstack, int flag);
+
+static int xtSplitUp(tid_t tid,
+		     struct inode *ip,
+		     struct xtsplit * split, struct btstack * btstack);
+
+static int xtSplitPage(tid_t tid, struct inode *ip, struct xtsplit * split,
+		       struct metapage ** rmpp, s64 * rbnp);
+
+static int xtSplitRoot(tid_t tid, struct inode *ip,
+		       struct xtsplit * split, struct metapage ** rmpp);
+
+/*
+ *	xtLookup()
+ *
+ * function: map a single page into a physical extent;
+ */
+int xtLookup(struct inode *ip, s64 lstart,
+	     s64 llen, int *pflag, s64 * paddr, s32 * plen, int no_check)
+{
+	int rc = 0;
+	struct btstack btstack;
+	int cmp;
+	s64 bn;
+	struct metapage *mp;
+	xtpage_t *p;
+	int index;
+	xad_t *xad;
+	s64 next, size, xoff, xend;
+	int xlen;
+	s64 xaddr;
+
+	*paddr = 0;
+	*plen = llen;
+
+	if (!no_check) {
+		/* is lookup offset beyond eof ? */
+		size = ((u64) ip->i_size + (JFS_SBI(ip->i_sb)->bsize - 1)) >>
+		    JFS_SBI(ip->i_sb)->l2bsize;
+		if (lstart >= size)
+			return 0;
+	}
+
+	/*
+	 * search for the xad entry covering the logical extent
+	 */
+//search:
+	if ((rc = xtSearch(ip, lstart, &next, &cmp, &btstack, 0))) {
+		jfs_err("xtLookup: xtSearch returned %d", rc);
+		return rc;
+	}
+
+	/*
+	 *	compute the physical extent covering logical extent
+	 *
+	 * N.B. search may have failed (e.g., hole in sparse file),
+	 * and returned the index of the next entry.
+	 */
+	/* retrieve search result */
+	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);
+
+	/* is xad found covering start of logical extent ?
+	 * lstart is a page start address,
+	 * i.e., lstart cannot start in a hole;
+	 */
+	if (cmp) {
+		if (next)
+			*plen = min(next - lstart, llen);
+		goto out;
+	}
+
+	/*
+	 * lxd covered by xad
+	 */
+	xad = &p->xad[index];
+	xoff = offsetXAD(xad);
+	xlen = lengthXAD(xad);
+	xend = xoff + xlen;
+	xaddr = addressXAD(xad);
+
+	/* initialize new pxd */
+	*pflag = xad->flag;
+	*paddr = xaddr + (lstart - xoff);
+	/* a page must be fully covered by an xad */
+	*plen = min(xend - lstart, llen);
+
+      out:
+	XT_PUTPAGE(mp);
+
+	return rc;
+}
+
+/*
+ *	xtSearch()
+ *
+ * function:	search for the xad entry covering specified offset.
+ *
+ * parameters:
+ *	ip	- file object;
+ *	xoff	- extent offset;
+ *	nextp	- address of next extent (if any) for search miss
+ *	cmpp	- comparison result:
+ *	btstack - traverse stack;
+ *	flag	- search process flag (XT_INSERT);
+ *
+ * returns:
+ *	btstack contains (bn, index) of search path traversed to the entry.
+ *	*cmpp is set to result of comparison with the entry returned.
+ *	the page containing the entry is pinned at exit.
+ */
+static int xtSearch(struct inode *ip, s64 xoff,	s64 *nextp,
+		    int *cmpp, struct btstack * btstack, int flag)
+{
+	struct jfs_inode_info *jfs_ip = JFS_IP(ip);
+	int rc = 0;
+	int cmp = 1;		/* init for empty page */
+	s64 bn;			/* block number */
+	struct metapage *mp;	/* page buffer */
+	xtpage_t *p;		/* page */
+	xad_t *xad;
+	int base, index, lim, btindex;
+	struct btframe *btsp;
+	int nsplit = 0;		/* number of pages to split */
+	s64 t64;
+	s64 next = 0;
+
+	INCREMENT(xtStat.search);
+
+	BT_CLR(btstack);
+
+	btstack->nsplit = 0;
+
+	/*
+	 *	search down tree from root:
+	 *
+	 * between two consecutive entries of <Ki, Pi> and <Kj, Pj> of
+	 * internal page, child page Pi contains entry with k, Ki <= K < Kj.
+	 *
+	 * if entry with search key K is not found
+	 * internal page search find the entry with largest key Ki
+	 * less than K which point to the child page to search;
+	 * leaf page search find the entry with smallest key Kj
+	 * greater than K so that the returned index is the position of
+	 * the entry to be shifted right for insertion of new entry.
+	 * for empty tree, search key is greater than any key of the tree.
+	 *
+	 * by convention, root bn = 0.
+	 */
+	for (bn = 0;;) {
+		/* get/pin the page to search */
+		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+		if (rc)
+			return rc;
+
+		/* try sequential access heuristics with the previous
+		 * access entry in target leaf page:
+		 * once search narrowed down into the target leaf,
+		 * key must either match an entry in the leaf or
+		 * key entry does not exist in the tree;
+		 */
+//fastSearch:
+		if ((jfs_ip->btorder & BT_SEQUENTIAL) &&
+		    (p->header.flag & BT_LEAF) &&
+		    (index = jfs_ip->btindex) <
+		    le16_to_cpu(p->header.nextindex)) {
+			xad = &p->xad[index];
+			t64 = offsetXAD(xad);
+			if (xoff < t64 + lengthXAD(xad)) {
+				if (xoff >= t64) {
+					*cmpp = 0;
+					goto out;
+				}
+
+				/* stop sequential access heuristics */
+				goto binarySearch;
+			} else {	/* (t64 + lengthXAD(xad)) <= xoff */
+
+				/* try next sequential entry */
+				index++;
+				if (index <
+				    le16_to_cpu(p->header.nextindex)) {
+					xad++;
+					t64 = offsetXAD(xad);
+					if (xoff < t64 + lengthXAD(xad)) {
+						if (xoff >= t64) {
+							*cmpp = 0;
+							goto out;
+						}
+
+						/* miss: key falls between
+						 * previous and this entry
+						 */
+						*cmpp = 1;
+						next = t64;
+						goto out;
+					}
+
+					/* (xoff >= t64 + lengthXAD(xad));
+					 * matching entry may be further out:
+					 * stop heuristic search
+					 */
+					/* stop sequential access heuristics */
+					goto binarySearch;
+				}
+
+				/* (index == p->header.nextindex);
+				 * miss: key entry does not exist in
+				 * the target leaf/tree
+				 */
+				*cmpp = 1;
+				goto out;
+			}
+
+			/*
+			 * if hit, return index of the entry found, and
+			 * if miss, where new entry with search key is
+			 * to be inserted;
+			 */
+		      out:
+			/* compute number of pages to split */
+			if (flag & XT_INSERT) {
+				if (p->header.nextindex ==	/* little-endian */
+				    p->header.maxentry)
+					nsplit++;
+				else
+					nsplit = 0;
+				btstack->nsplit = nsplit;
+			}
+
+			/* save search result */
+			btsp = btstack->top;
+			btsp->bn = bn;
+			btsp->index = index;
+			btsp->mp = mp;
+
+			/* update sequential access heuristics */
+			jfs_ip->btindex = index;
+
+			if (nextp)
+				*nextp = next;
+
+			INCREMENT(xtStat.fastSearch);
+			return 0;
+		}
+
+		/* well, ... full search now */
+	      binarySearch:
+		lim = le16_to_cpu(p->header.nextindex) - XTENTRYSTART;
+
+		/*
+		 * binary search with search key K on the current page
+		 */
+		for (base = XTENTRYSTART; lim; lim >>= 1) {
+			index = base + (lim >> 1);
+
+			XT_CMP(cmp, xoff, &p->xad[index], t64);
+			if (cmp == 0) {
+				/*
+				 *	search hit
+				 */
+				/* search hit - leaf page:
+				 * return the entry found
+				 */
+				if (p->header.flag & BT_LEAF) {
+					*cmpp = cmp;
+
+					/* compute number of pages to split */
+					if (flag & XT_INSERT) {
+						if (p->header.nextindex ==
+						    p->header.maxentry)
+							nsplit++;
+						else
+							nsplit = 0;
+						btstack->nsplit = nsplit;
+					}
+
+					/* save search result */
+					btsp = btstack->top;
+					btsp->bn = bn;
+					btsp->index = index;
+					btsp->mp = mp;
+
+					/* init sequential access heuristics */
+					btindex = jfs_ip->btindex;
+					if (index == btindex ||
+					    index == btindex + 1)
+						jfs_ip->btorder = BT_SEQUENTIAL;
+					else
+						jfs_ip->btorder = BT_RANDOM;
+					jfs_ip->btindex = index;
+
+					return 0;
+				}
+				/* search hit - internal page:
+				 * descend/search its child page
+				 */
+				if (index < le16_to_cpu(p->header.nextindex)-1)
+					next = offsetXAD(&p->xad[index + 1]);
+				goto next;
+			}
+
+			if (cmp > 0) {
+				base = index + 1;
+				--lim;
+			}
+		}
+
+		/*
+		 *	search miss
+		 *
+		 * base is the smallest index with key (Kj) greater than
+		 * search key (K) and may be zero or maxentry index.
+		 */
+		if (base < le16_to_cpu(p->header.nextindex))
+			next = offsetXAD(&p->xad[base]);
+		/*
+		 * search miss - leaf page:
+		 *
+		 * return location of entry (base) where new entry with
+		 * search key K is to be inserted.
+		 */
+		if (p->header.flag & BT_LEAF) {
+			*cmpp = cmp;
+
+			/* compute number of pages to split */
+			if (flag & XT_INSERT) {
+				if (p->header.nextindex ==
+				    p->header.maxentry)
+					nsplit++;
+				else
+					nsplit = 0;
+				btstack->nsplit = nsplit;
+			}
+
+			/* save search result */
+			btsp = btstack->top;
+			btsp->bn = bn;
+			btsp->index = base;
+			btsp->mp = mp;
+
+			/* init sequential access heuristics */
+			btindex = jfs_ip->btindex;
+			if (base == btindex || base == btindex + 1)
+				jfs_ip->btorder = BT_SEQUENTIAL;
+			else
+				jfs_ip->btorder = BT_RANDOM;
+			jfs_ip->btindex = base;
+
+			if (nextp)
+				*nextp = next;
+
+			return 0;
+		}
+
+		/*
+		 * search miss - non-leaf page:
+		 *
+		 * if base is non-zero, decrement base by one to get the parent
+		 * entry of the child page to search.
+		 */
+		index = base ? base - 1 : base;
+
+		/*
+		 * go down to child page
+		 */
+	      next:
+		/* update number of pages to split */
+		if (p->header.nextindex == p->header.maxentry)
+			nsplit++;
+		else
+			nsplit = 0;
+
+		/* push (bn, index) of the parent page/entry */
+		if (BT_STACK_FULL(btstack)) {
+			jfs_error(ip->i_sb, "stack overrun!\n");
+			XT_PUTPAGE(mp);
+			return -EIO;
+		}
+		BT_PUSH(btstack, bn, index);
+
+		/* get the child page block number */
+		bn = addressXAD(&p->xad[index]);
+
+		/* unpin the parent page */
+		XT_PUTPAGE(mp);
+	}
+}
+
+/*
+ *	xtInsert()
+ *
+ * function:
+ *
+ * parameter:
+ *	tid	- transaction id;
+ *	ip	- file object;
+ *	xflag	- extent flag (XAD_NOTRECORDED):
+ *	xoff	- extent offset;
+ *	xlen	- extent length;
+ *	xaddrp	- extent address pointer (in/out):
+ *		if (*xaddrp)
+ *			caller allocated data extent at *xaddrp;
+ *		else
+ *			allocate data extent and return its xaddr;
+ *	flag	-
+ *
+ * return:
+ */
+int xtInsert(tid_t tid,		/* transaction id */
+	     struct inode *ip, int xflag, s64 xoff, s32 xlen, s64 * xaddrp,
+	     int flag)
+{
+	int rc = 0;
+	s64 xaddr, hint;
+	struct metapage *mp;	/* meta-page buffer */
+	xtpage_t *p;		/* base B+-tree index page */
+	s64 bn;
+	int index, nextindex;
+	struct btstack btstack;	/* traverse stack */
+	struct xtsplit split;	/* split information */
+	xad_t *xad;
+	int cmp;
+	s64 next;
+	struct tlock *tlck;
+	struct xtlock *xtlck;
+
+	jfs_info("xtInsert: nxoff:0x%lx nxlen:0x%x", (ulong) xoff, xlen);
+
+	/*
+	 *	search for the entry location at which to insert:
+	 *
+	 * xtFastSearch() and xtSearch() both returns (leaf page
+	 * pinned, index at which to insert).
+	 * n.b. xtSearch() may return index of maxentry of
+	 * the full page.
+	 */
+	if ((rc = xtSearch(ip, xoff, &next, &cmp, &btstack, XT_INSERT)))
+		return rc;
+
+	/* retrieve search result */
+	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);
+
+	/* This test must follow XT_GETSEARCH since mp must be valid if
+	 * we branch to out: */
+	if ((cmp == 0) || (next && (xlen > next - xoff))) {
+		rc = -EEXIST;
+		goto out;
+	}
+
+	/*
+	 * allocate data extent requested
+	 *
+	 * allocation hint: last xad
+	 */
+	if ((xaddr = *xaddrp) == 0) {
+		if (index > XTENTRYSTART) {
+			xad = &p->xad[index - 1];
+			hint = addressXAD(xad) + lengthXAD(xad) - 1;
+		} else
+			hint = 0;
+		if ((rc = dquot_alloc_block(ip, xlen)))
+			goto out;
+		if ((rc = dbAlloc(ip, hint, (s64) xlen, &xaddr))) {
+			dquot_free_block(ip, xlen);
+			goto out;
+		}
+	}
+
+	/*
+	 *	insert entry for new extent
+	 */
+	xflag |= XAD_NEW;
+
+	/*
+	 *	if the leaf page is full, split the page and
+	 *	propagate up the router entry for the new page from split
+	 *
+	 * The xtSplitUp() will insert the entry and unpin the leaf page.
+	 */
+	nextindex = le16_to_cpu(p->header.nextindex);
+	if (nextindex == le16_to_cpu(p->header.maxentry)) {
+		split.mp = mp;
+		split.index = index;
+		split.flag = xflag;
+		split.off = xoff;
+		split.len = xlen;
+		split.addr = xaddr;
+		split.pxdlist = NULL;
+		if ((rc = xtSplitUp(tid, ip, &split, &btstack))) {
+			/* undo data extent allocation */
+			if (*xaddrp == 0) {
+				dbFree(ip, xaddr, (s64) xlen);
+				dquot_free_block(ip, xlen);
+			}
+			return rc;
+		}
+
+		*xaddrp = xaddr;
+		return 0;
+	}
+
+	/*
+	 *	insert the new entry into the leaf page
+	 */
+	/*
+	 * acquire a transaction lock on the leaf page;
+	 *
+	 * action: xad insertion/extension;
+	 */
+	BT_MARK_DIRTY(mp, ip);
+
+	/* if insert into middle, shift right remaining entries. */
+	if (index < nextindex)
+		memmove(&p->xad[index + 1], &p->xad[index],
+			(nextindex - index) * sizeof(xad_t));
+
+	/* insert the new entry: mark the entry NEW */
+	xad = &p->xad[index];
+	XT_PUTENTRY(xad, xflag, xoff, xlen, xaddr);
+
+	/* advance next available entry index */
+	le16_add_cpu(&p->header.nextindex, 1);
+
+	/* Don't log it if there are no links to the file */
+	if (!test_cflag(COMMIT_Nolink, ip)) {
+		tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
+		xtlck = (struct xtlock *) & tlck->lock;
+		xtlck->lwm.offset =
+		    (xtlck->lwm.offset) ? min(index,
+					      (int)xtlck->lwm.offset) : index;
+		xtlck->lwm.length =
+		    le16_to_cpu(p->header.nextindex) - xtlck->lwm.offset;
+	}
+
+	*xaddrp = xaddr;
+
+      out:
+	/* unpin the leaf page */
+	XT_PUTPAGE(mp);
+
+	return rc;
+}
+
+
+/*
+ *	xtSplitUp()
+ *
+ * function:
+ *	split full pages as propagating insertion up the tree
+ *
+ * parameter:
+ *	tid	- transaction id;
+ *	ip	- file object;
+ *	split	- entry parameter descriptor;
+ *	btstack - traverse stack from xtSearch()
+ *
+ * return:
+ */
+static int
+xtSplitUp(tid_t tid,
+	  struct inode *ip, struct xtsplit * split, struct btstack * btstack)
+{
+	int rc = 0;
+	struct metapage *smp;
+	xtpage_t *sp;		/* split page */
+	struct metapage *rmp;
+	s64 rbn;		/* new right page block number */
+	struct metapage *rcmp;
+	xtpage_t *rcp;		/* right child page */
+	s64 rcbn;		/* right child page block number */
+	int skip;		/* index of entry of insertion */
+	int nextindex;		/* next available entry index of p */
+	struct btframe *parent;	/* parent page entry on traverse stack */
+	xad_t *xad;
+	s64 xaddr;
+	int xlen;
+	int nsplit;		/* number of pages split */
+	struct pxdlist pxdlist;
+	pxd_t *pxd;
+	struct tlock *tlck;
+	struct xtlock *xtlck;
+
+	smp = split->mp;
+	sp = XT_PAGE(ip, smp);
+
+	/* is inode xtree root extension/inline EA area free ? */
+	if ((sp->header.flag & BT_ROOT) && (!S_ISDIR(ip->i_mode)) &&
+	    (le16_to_cpu(sp->header.maxentry) < XTROOTMAXSLOT) &&
+	    (JFS_IP(ip)->mode2 & INLINEEA)) {
+		sp->header.maxentry = cpu_to_le16(XTROOTMAXSLOT);
+		JFS_IP(ip)->mode2 &= ~INLINEEA;
+
+		BT_MARK_DIRTY(smp, ip);
+		/*
+		 * acquire a transaction lock on the leaf page;
+		 *
+		 * action: xad insertion/extension;
+		 */
+
+		/* if insert into middle, shift right remaining entries. */
+		skip = split->index;
+		nextindex = le16_to_cpu(sp->header.nextindex);
+		if (skip < nextindex)
+			memmove(&sp->xad[skip + 1], &sp->xad[skip],
+				(nextindex - skip) * sizeof(xad_t));
+
+		/* insert the new entry: mark the entry NEW */
+		xad = &sp->xad[skip];
+		XT_PUTENTRY(xad, split->flag, split->off, split->len,
+			    split->addr);
+
+		/* advance next available entry index */
+		le16_add_cpu(&sp->header.nextindex, 1);
+
+		/* Don't log it if there are no links to the file */
+		if (!test_cflag(COMMIT_Nolink, ip)) {
+			tlck = txLock(tid, ip, smp, tlckXTREE | tlckGROW);
+			xtlck = (struct xtlock *) & tlck->lock;
+			xtlck->lwm.offset = (xtlck->lwm.offset) ?
+			    min(skip, (int)xtlck->lwm.offset) : skip;
+			xtlck->lwm.length =
+			    le16_to_cpu(sp->header.nextindex) -
+			    xtlck->lwm.offset;
+		}
+
+		return 0;
+	}
+
+	/*
+	 * allocate new index blocks to cover index page split(s)
+	 *
+	 * allocation hint: ?
+	 */
+	if (split->pxdlist == NULL) {
+		nsplit = btstack->nsplit;
+		split->pxdlist = &pxdlist;
+		pxdlist.maxnpxd = pxdlist.npxd = 0;
+		pxd = &pxdlist.pxd[0];
+		xlen = JFS_SBI(ip->i_sb)->nbperpage;
+		for (; nsplit > 0; nsplit--, pxd++) {
+			if ((rc = dbAlloc(ip, (s64) 0, (s64) xlen, &xaddr))
+			    == 0) {
+				PXDaddress(pxd, xaddr);
+				PXDlength(pxd, xlen);
+
+				pxdlist.maxnpxd++;
+
+				continue;
+			}
+
+			/* undo allocation */
+
+			XT_PUTPAGE(smp);
+			return rc;
+		}
+	}
+
+	/*
+	 * Split leaf page <sp> into <sp> and a new right page <rp>.
+	 *
+	 * The split routines insert the new entry into the leaf page,
+	 * and acquire txLock as appropriate.
+	 * return <rp> pinned and its block number <rpbn>.
+	 */
+	rc = (sp->header.flag & BT_ROOT) ?
+	    xtSplitRoot(tid, ip, split, &rmp) :
+	    xtSplitPage(tid, ip, split, &rmp, &rbn);
+
+	XT_PUTPAGE(smp);
+
+	if (rc)
+		return -EIO;
+	/*
+	 * propagate up the router entry for the leaf page just split
+	 *
+	 * insert a router entry for the new page into the parent page,
+	 * propagate the insert/split up the tree by walking back the stack
+	 * of (bn of parent page, index of child page entry in parent page)
+	 * that were traversed during the search for the page that split.
+	 *
+	 * the propagation of insert/split up the tree stops if the root
+	 * splits or the page inserted into doesn't have to split to hold
+	 * the new entry.
+	 *
+	 * the parent entry for the split page remains the same, and
+	 * a new entry is inserted at its right with the first key and
+	 * block number of the new right page.
+	 *
+	 * There are a maximum of 3 pages pinned at any time:
+	 * right child, left parent and right parent (when the parent splits)
+	 * to keep the child page pinned while working on the parent.
+	 * make sure that all pins are released at exit.
+	 */
+	while ((parent = BT_POP(btstack)) != NULL) {
+		/* parent page specified by stack frame <parent> */
+
+		/* keep current child pages <rcp> pinned */
+		rcmp = rmp;
+		rcbn = rbn;
+		rcp = XT_PAGE(ip, rcmp);
+
+		/*
+		 * insert router entry in parent for new right child page <rp>
+		 */
+		/* get/pin the parent page <sp> */
+		XT_GETPAGE(ip, parent->bn, smp, PSIZE, sp, rc);
+		if (rc) {
+			XT_PUTPAGE(rcmp);
+			return rc;
+		}
+
+		/*
+		 * The new key entry goes ONE AFTER the index of parent entry,
+		 * because the split was to the right.
+		 */
+		skip = parent->index + 1;
+
+		/*
+		 * split or shift right remaining entries of the parent page
+		 */
+		nextindex = le16_to_cpu(sp->header.nextindex);
+		/*
+		 * parent page is full - split the parent page
+		 */
+		if (nextindex == le16_to_cpu(sp->header.maxentry)) {
+			/* init for parent page split */
+			split->mp = smp;
+			split->index = skip;	/* index at insert */
+			split->flag = XAD_NEW;
+			split->off = offsetXAD(&rcp->xad[XTENTRYSTART]);
+			split->len = JFS_SBI(ip->i_sb)->nbperpage;
+			split->addr = rcbn;
+
+			/* unpin previous right child page */
+			XT_PUTPAGE(rcmp);
+
+			/* The split routines insert the new entry,
+			 * and acquire txLock as appropriate.
+			 * return <rp> pinned and its block number <rpbn>.
+			 */
+			rc = (sp->header.flag & BT_ROOT) ?
+			    xtSplitRoot(tid, ip, split, &rmp) :
+			    xtSplitPage(tid, ip, split, &rmp, &rbn);
+			if (rc) {
+				XT_PUTPAGE(smp);
+				return rc;
+			}
+
+			XT_PUTPAGE(smp);
+			/* keep new child page <rp> pinned */
+		}
+		/*
+		 * parent page is not full - insert in parent page
+		 */
+		else {
+			/*
+			 * insert router entry in parent for the right child
+			 * page from the first entry of the right child page:
+			 */
+			/*
+			 * acquire a transaction lock on the parent page;
+			 *
+			 * action: router xad insertion;
+			 */
+			BT_MARK_DIRTY(smp, ip);
+
+			/*
+			 * if insert into middle, shift right remaining entries
+			 */
+			if (skip < nextindex)
+				memmove(&sp->xad[skip + 1], &sp->xad[skip],
+					(nextindex -
+					 skip) << L2XTSLOTSIZE);
+
+			/* insert the router entry */
+			xad = &sp->xad[skip];
+			XT_PUTENTRY(xad, XAD_NEW,
+				    offsetXAD(&rcp->xad[XTENTRYSTART]),
+				    JFS_SBI(ip->i_sb)->nbperpage, rcbn);
+
+			/* advance next available entry index. */
+			le16_add_cpu(&sp->header.nextindex, 1);
+
+			/* Don't log it if there are no links to the file */
+			if (!test_cflag(COMMIT_Nolink, ip)) {
+				tlck = txLock(tid, ip, smp,
+					      tlckXTREE | tlckGROW);
+				xtlck = (struct xtlock *) & tlck->lock;
+				xtlck->lwm.offset = (xtlck->lwm.offset) ?
+				    min(skip, (int)xtlck->lwm.offset) : skip;
+				xtlck->lwm.length =
+				    le16_to_cpu(sp->header.nextindex) -
+				    xtlck->lwm.offset;
+			}
+
+			/* unpin parent page */
+			XT_PUTPAGE(smp);
+
+			/* exit propagate up */
+			break;
+		}
+	}
+
+	/* unpin current right page */
+	XT_PUTPAGE(rmp);
+
+	return 0;
+}
+
+
+/*
+ *	xtSplitPage()
+ *
+ * function:
+ *	split a full non-root page into
+ *	original/split/left page and new right page
+ *	i.e., the original/split page remains as left page.
+ *
+ * parameter:
+ *	int		tid,
+ *	struct inode	*ip,
+ *	struct xtsplit	*split,
+ *	struct metapage	**rmpp,
+ *	u64		*rbnp,
+ *
+ * return:
+ *	Pointer to page in which to insert or NULL on error.
+ */
+static int
+xtSplitPage(tid_t tid, struct inode *ip,
+	    struct xtsplit * split, struct metapage ** rmpp, s64 * rbnp)
+{
+	int rc = 0;
+	struct metapage *smp;
+	xtpage_t *sp;
+	struct metapage *rmp;
+	xtpage_t *rp;		/* new right page allocated */
+	s64 rbn;		/* new right page block number */
+	struct metapage *mp;
+	xtpage_t *p;
+	s64 nextbn;
+	int skip, maxentry, middle, righthalf, n;
+	xad_t *xad;
+	struct pxdlist *pxdlist;
+	pxd_t *pxd;
+	struct tlock *tlck;
+	struct xtlock *sxtlck = NULL, *rxtlck = NULL;
+	int quota_allocation = 0;
+
+	smp = split->mp;
+	sp = XT_PAGE(ip, smp);
+
+	INCREMENT(xtStat.split);
+
+	pxdlist = split->pxdlist;
+	pxd = &pxdlist->pxd[pxdlist->npxd];
+	pxdlist->npxd++;
+	rbn = addressPXD(pxd);
+
+	/* Allocate blocks to quota. */
+	rc = dquot_alloc_block(ip, lengthPXD(pxd));
+	if (rc)
+		goto clean_up;
+
+	quota_allocation += lengthPXD(pxd);
+
+	/*
+	 * allocate the new right page for the split
+	 */
+	rmp = get_metapage(ip, rbn, PSIZE, 1);
+	if (rmp == NULL) {
+		rc = -EIO;
+		goto clean_up;
+	}
+
+	jfs_info("xtSplitPage: ip:0x%p smp:0x%p rmp:0x%p", ip, smp, rmp);
+
+	BT_MARK_DIRTY(rmp, ip);
+	/*
+	 * action: new page;
+	 */
+
+	rp = (xtpage_t *) rmp->data;
+	rp->header.self = *pxd;
+	rp->header.flag = sp->header.flag & BT_TYPE;
+	rp->header.maxentry = sp->header.maxentry;	/* little-endian */
+	rp->header.nextindex = cpu_to_le16(XTENTRYSTART);
+
+	BT_MARK_DIRTY(smp, ip);
+	/* Don't log it if there are no links to the file */
+	if (!test_cflag(COMMIT_Nolink, ip)) {
+		/*
+		 * acquire a transaction lock on the new right page;
+		 */
+		tlck = txLock(tid, ip, rmp, tlckXTREE | tlckNEW);
+		rxtlck = (struct xtlock *) & tlck->lock;
+		rxtlck->lwm.offset = XTENTRYSTART;
+		/*
+		 * acquire a transaction lock on the split page
+		 */
+		tlck = txLock(tid, ip, smp, tlckXTREE | tlckGROW);
+		sxtlck = (struct xtlock *) & tlck->lock;
+	}
+
+	/*
+	 * initialize/update sibling pointers of <sp> and <rp>
+	 */
+	nextbn = le64_to_cpu(sp->header.next);
+	rp->header.next = cpu_to_le64(nextbn);
+	rp->header.prev = cpu_to_le64(addressPXD(&sp->header.self));
+	sp->header.next = cpu_to_le64(rbn);
+
+	skip = split->index;
+
+	/*
+	 *	sequential append at tail (after last entry of last page)
+	 *
+	 * if splitting the last page on a level because of appending
+	 * a entry to it (skip is maxentry), it's likely that the access is
+	 * sequential. adding an empty page on the side of the level is less
+	 * work and can push the fill factor much higher than normal.
+	 * if we're wrong it's no big deal -  we will do the split the right
+	 * way next time.
+	 * (it may look like it's equally easy to do a similar hack for
+	 * reverse sorted data, that is, split the tree left, but it's not.
+	 * Be my guest.)
+	 */
+	if (nextbn == 0 && skip == le16_to_cpu(sp->header.maxentry)) {
+		/*
+		 * acquire a transaction lock on the new/right page;
+		 *
+		 * action: xad insertion;
+		 */
+		/* insert entry at the first entry of the new right page */
+		xad = &rp->xad[XTENTRYSTART];
+		XT_PUTENTRY(xad, split->flag, split->off, split->len,
+			    split->addr);
+
+		rp->header.nextindex = cpu_to_le16(XTENTRYSTART + 1);
+
+		if (!test_cflag(COMMIT_Nolink, ip)) {
+			/* rxtlck->lwm.offset = XTENTRYSTART; */
+			rxtlck->lwm.length = 1;
+		}
+
+		*rmpp = rmp;
+		*rbnp = rbn;
+
+		jfs_info("xtSplitPage: sp:0x%p rp:0x%p", sp, rp);
+		return 0;
+	}
+
+	/*
+	 *	non-sequential insert (at possibly middle page)
+	 */
+
+	/*
+	 * update previous pointer of old next/right page of <sp>
+	 */
+	if (nextbn != 0) {
+		XT_GETPAGE(ip, nextbn, mp, PSIZE, p, rc);
+		if (rc) {
+			XT_PUTPAGE(rmp);
+			goto clean_up;
+		}
+
+		BT_MARK_DIRTY(mp, ip);
+		/*
+		 * acquire a transaction lock on the next page;
+		 *
+		 * action:sibling pointer update;
+		 */
+		if (!test_cflag(COMMIT_Nolink, ip))
+			tlck = txLock(tid, ip, mp, tlckXTREE | tlckRELINK);
+
+		p->header.prev = cpu_to_le64(rbn);
+
+		/* sibling page may have been updated previously, or
+		 * it may be updated later;
+		 */
+
+		XT_PUTPAGE(mp);
+	}
+
+	/*
+	 * split the data between the split and new/right pages
+	 */
+	maxentry = le16_to_cpu(sp->header.maxentry);
+	middle = maxentry >> 1;
+	righthalf = maxentry - middle;
+
+	/*
+	 * skip index in old split/left page - insert into left page:
+	 */
+	if (skip <= middle) {
+		/* move right half of split page to the new right page */
+		memmove(&rp->xad[XTENTRYSTART], &sp->xad[middle],
+			righthalf << L2XTSLOTSIZE);
+
+		/* shift right tail of left half to make room for new entry */
+		if (skip < middle)
+			memmove(&sp->xad[skip + 1], &sp->xad[skip],
+				(middle - skip) << L2XTSLOTSIZE);
+
+		/* insert new entry */
+		xad = &sp->xad[skip];
+		XT_PUTENTRY(xad, split->flag, split->off, split->len,
+			    split->addr);
+
+		/* update page header */
+		sp->header.nextindex = cpu_to_le16(middle + 1);
+		if (!test_cflag(COMMIT_Nolink, ip)) {
+			sxtlck->lwm.offset = (sxtlck->lwm.offset) ?
+			    min(skip, (int)sxtlck->lwm.offset) : skip;
+		}
+
+		rp->header.nextindex =
+		    cpu_to_le16(XTENTRYSTART + righthalf);
+	}
+	/*
+	 * skip index in new right page - insert into right page:
+	 */
+	else {
+		/* move left head of right half to right page */
+		n = skip - middle;
+		memmove(&rp->xad[XTENTRYSTART], &sp->xad[middle],
+			n << L2XTSLOTSIZE);
+
+		/* insert new entry */
+		n += XTENTRYSTART;
+		xad = &rp->xad[n];
+		XT_PUTENTRY(xad, split->flag, split->off, split->len,
+			    split->addr);
+
+		/* move right tail of right half to right page */
+		if (skip < maxentry)
+			memmove(&rp->xad[n + 1], &sp->xad[skip],
+				(maxentry - skip) << L2XTSLOTSIZE);
+
+		/* update page header */
+		sp->header.nextindex = cpu_to_le16(middle);
+		if (!test_cflag(COMMIT_Nolink, ip)) {
+			sxtlck->lwm.offset = (sxtlck->lwm.offset) ?
+			    min(middle, (int)sxtlck->lwm.offset) : middle;
+		}
+
+		rp->header.nextindex = cpu_to_le16(XTENTRYSTART +
+						   righthalf + 1);
+	}
+
+	if (!test_cflag(COMMIT_Nolink, ip)) {
+		sxtlck->lwm.length = le16_to_cpu(sp->header.nextindex) -
+		    sxtlck->lwm.offset;
+
+		/* rxtlck->lwm.offset = XTENTRYSTART; */
+		rxtlck->lwm.length = le16_to_cpu(rp->header.nextindex) -
+		    XTENTRYSTART;
+	}
+
+	*rmpp = rmp;
+	*rbnp = rbn;
+
+	jfs_info("xtSplitPage: sp:0x%p rp:0x%p", sp, rp);
+	return rc;
+
+      clean_up:
+
+	/* Rollback quota allocation. */
+	if (quota_allocation)
+		dquot_free_block(ip, quota_allocation);
+
+	return (rc);
+}
+
+
+/*
+ *	xtSplitRoot()
+ *
+ * function:
+ *	split the full root page into original/root/split page and new
+ *	right page
+ *	i.e., root remains fixed in tree anchor (inode) and the root is
+ *	copied to a single new right child page since root page <<
+ *	non-root page, and the split root page contains a single entry
+ *	for the new right child page.
+ *
+ * parameter:
+ *	int		tid,
+ *	struct inode	*ip,
+ *	struct xtsplit	*split,
+ *	struct metapage	**rmpp)
+ *
+ * return:
+ *	Pointer to page in which to insert or NULL on error.
+ */
+static int
+xtSplitRoot(tid_t tid,
+	    struct inode *ip, struct xtsplit * split, struct metapage ** rmpp)
+{
+	xtpage_t *sp;
+	struct metapage *rmp;
+	xtpage_t *rp;
+	s64 rbn;
+	int skip, nextindex;
+	xad_t *xad;
+	pxd_t *pxd;
+	struct pxdlist *pxdlist;
+	struct tlock *tlck;
+	struct xtlock *xtlck;
+	int rc;
+
+	sp = &JFS_IP(ip)->i_xtroot;
+
+	INCREMENT(xtStat.split);
+
+	/*
+	 *	allocate a single (right) child page
+	 */
+	pxdlist = split->pxdlist;
+	pxd = &pxdlist->pxd[pxdlist->npxd];
+	pxdlist->npxd++;
+	rbn = addressPXD(pxd);
+	rmp = get_metapage(ip, rbn, PSIZE, 1);
+	if (rmp == NULL)
+		return -EIO;
+
+	/* Allocate blocks to quota. */
+	rc = dquot_alloc_block(ip, lengthPXD(pxd));
+	if (rc) {
+		release_metapage(rmp);
+		return rc;
+	}
+
+	jfs_info("xtSplitRoot: ip:0x%p rmp:0x%p", ip, rmp);
+
+	/*
+	 * acquire a transaction lock on the new right page;
+	 *
+	 * action: new page;
+	 */
+	BT_MARK_DIRTY(rmp, ip);
+
+	rp = (xtpage_t *) rmp->data;
+	rp->header.flag =
+	    (sp->header.flag & BT_LEAF) ? BT_LEAF : BT_INTERNAL;
+	rp->header.self = *pxd;
+	rp->header.nextindex = cpu_to_le16(XTENTRYSTART);
+	rp->header.maxentry = cpu_to_le16(PSIZE >> L2XTSLOTSIZE);
+
+	/* initialize sibling pointers */
+	rp->header.next = 0;
+	rp->header.prev = 0;
+
+	/*
+	 * copy the in-line root page into new right page extent
+	 */
+	nextindex = le16_to_cpu(sp->header.maxentry);
+	memmove(&rp->xad[XTENTRYSTART], &sp->xad[XTENTRYSTART],
+		(nextindex - XTENTRYSTART) << L2XTSLOTSIZE);
+
+	/*
+	 * insert the new entry into the new right/child page
+	 * (skip index in the new right page will not change)
+	 */
+	skip = split->index;
+	/* if insert into middle, shift right remaining entries */
+	if (skip != nextindex)
+		memmove(&rp->xad[skip + 1], &rp->xad[skip],
+			(nextindex - skip) * sizeof(xad_t));
+
+	xad = &rp->xad[skip];
+	XT_PUTENTRY(xad, split->flag, split->off, split->len, split->addr);
+
+	/* update page header */
+	rp->header.nextindex = cpu_to_le16(nextindex + 1);
+
+	if (!test_cflag(COMMIT_Nolink, ip)) {
+		tlck = txLock(tid, ip, rmp, tlckXTREE | tlckNEW);
+		xtlck = (struct xtlock *) & tlck->lock;
+		xtlck->lwm.offset = XTENTRYSTART;
+		xtlck->lwm.length = le16_to_cpu(rp->header.nextindex) -
+		    XTENTRYSTART;
+	}
+
+	/*
+	 *	reset the root
+	 *
+	 * init root with the single entry for the new right page
+	 * set the 1st entry offset to 0, which force the left-most key
+	 * at any level of the tree to be less than any search key.
+	 */
+	/*
+	 * acquire a transaction lock on the root page (in-memory inode);
+	 *
+	 * action: root split;
+	 */
+	BT_MARK_DIRTY(split->mp, ip);
+
+	xad = &sp->xad[XTENTRYSTART];
+	XT_PUTENTRY(xad, XAD_NEW, 0, JFS_SBI(ip->i_sb)->nbperpage, rbn);
+
+	/* update page header of root */
+	sp->header.flag &= ~BT_LEAF;
+	sp->header.flag |= BT_INTERNAL;
+
+	sp->header.nextindex = cpu_to_le16(XTENTRYSTART + 1);
+
+	if (!test_cflag(COMMIT_Nolink, ip)) {
+		tlck = txLock(tid, ip, split->mp, tlckXTREE | tlckGROW);
+		xtlck = (struct xtlock *) & tlck->lock;
+		xtlck->lwm.offset = XTENTRYSTART;
+		xtlck->lwm.length = 1;
+	}
+
+	*rmpp = rmp;
+
+	jfs_info("xtSplitRoot: sp:0x%p rp:0x%p", sp, rp);
+	return 0;
+}
+
+
+/*
+ *	xtExtend()
+ *
+ * function: extend in-place;
+ *
+ * note: existing extent may or may not have been committed.
+ * caller is responsible for pager buffer cache update, and
+ * working block allocation map update;
+ * update pmap: alloc whole extended extent;
+ */
+int xtExtend(tid_t tid,		/* transaction id */
+	     struct inode *ip, s64 xoff,	/* delta extent offset */
+	     s32 xlen,		/* delta extent length */
+	     int flag)
+{
+	int rc = 0;
+	int cmp;
+	struct metapage *mp;	/* meta-page buffer */
+	xtpage_t *p;		/* base B+-tree index page */
+	s64 bn;
+	int index, nextindex, len;
+	struct btstack btstack;	/* traverse stack */
+	struct xtsplit split;	/* split information */
+	xad_t *xad;
+	s64 xaddr;
+	struct tlock *tlck;
+	struct xtlock *xtlck = NULL;
+
+	jfs_info("xtExtend: nxoff:0x%lx nxlen:0x%x", (ulong) xoff, xlen);
+
+	/* there must exist extent to be extended */
+	if ((rc = xtSearch(ip, xoff - 1, NULL, &cmp, &btstack, XT_INSERT)))
+		return rc;
+
+	/* retrieve search result */
+	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);
+
+	if (cmp != 0) {
+		XT_PUTPAGE(mp);
+		jfs_error(ip->i_sb, "xtSearch did not find extent\n");
+		return -EIO;
+	}
+
+	/* extension must be contiguous */
+	xad = &p->xad[index];
+	if ((offsetXAD(xad) + lengthXAD(xad)) != xoff) {
+		XT_PUTPAGE(mp);
+		jfs_error(ip->i_sb, "extension is not contiguous\n");
+		return -EIO;
+	}
+
+	/*
+	 * acquire a transaction lock on the leaf page;
+	 *
+	 * action: xad insertion/extension;
+	 */
+	BT_MARK_DIRTY(mp, ip);
+	if (!test_cflag(COMMIT_Nolink, ip)) {
+		tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
+		xtlck = (struct xtlock *) & tlck->lock;
+	}
+
+	/* extend will overflow extent ? */
+	xlen = lengthXAD(xad) + xlen;
+	if ((len = xlen - MAXXLEN) <= 0)
+		goto extendOld;
+
+	/*
+	 *	extent overflow: insert entry for new extent
+	 */
+//insertNew:
+	xoff = offsetXAD(xad) + MAXXLEN;
+	xaddr = addressXAD(xad) + MAXXLEN;
+	nextindex = le16_to_cpu(p->header.nextindex);
+
+	/*
+	 *	if the leaf page is full, insert the new entry and
+	 *	propagate up the router entry for the new page from split
+	 *
+	 * The xtSplitUp() will insert the entry and unpin the leaf page.
+	 */
+	if (nextindex == le16_to_cpu(p->header.maxentry)) {
+		/* xtSpliUp() unpins leaf pages */
+		split.mp = mp;
+		split.index = index + 1;
+		split.flag = XAD_NEW;
+		split.off = xoff;	/* split offset */
+		split.len = len;
+		split.addr = xaddr;
+		split.pxdlist = NULL;
+		if ((rc = xtSplitUp(tid, ip, &split, &btstack)))
+			return rc;
+
+		/* get back old page */
+		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+		if (rc)
+			return rc;
+		/*
+		 * if leaf root has been split, original root has been
+		 * copied to new child page, i.e., original entry now
+		 * resides on the new child page;
+		 */
+		if (p->header.flag & BT_INTERNAL) {
+			ASSERT(p->header.nextindex ==
+			       cpu_to_le16(XTENTRYSTART + 1));
+			xad = &p->xad[XTENTRYSTART];
+			bn = addressXAD(xad);
+			XT_PUTPAGE(mp);
+
+			/* get new child page */
+			XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+			if (rc)
+				return rc;
+
+			BT_MARK_DIRTY(mp, ip);
+			if (!test_cflag(COMMIT_Nolink, ip)) {
+				tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
+				xtlck = (struct xtlock *) & tlck->lock;
+			}
+		}
+	}
+	/*
+	 *	insert the new entry into the leaf page
+	 */
+	else {
+		/* insert the new entry: mark the entry NEW */
+		xad = &p->xad[index + 1];
+		XT_PUTENTRY(xad, XAD_NEW, xoff, len, xaddr);
+
+		/* advance next available entry index */
+		le16_add_cpu(&p->header.nextindex, 1);
+	}
+
+	/* get back old entry */
+	xad = &p->xad[index];
+	xlen = MAXXLEN;
+
+	/*
+	 * extend old extent
+	 */
+      extendOld:
+	XADlength(xad, xlen);
+	if (!(xad->flag & XAD_NEW))
+		xad->flag |= XAD_EXTENDED;
+
+	if (!test_cflag(COMMIT_Nolink, ip)) {
+		xtlck->lwm.offset =
+		    (xtlck->lwm.offset) ? min(index,
+					      (int)xtlck->lwm.offset) : index;
+		xtlck->lwm.length =
+		    le16_to_cpu(p->header.nextindex) - xtlck->lwm.offset;
+	}
+
+	/* unpin the leaf page */
+	XT_PUTPAGE(mp);
+
+	return rc;
+}
+
+/*
+ *	xtUpdate()
+ *
+ * function: update XAD;
+ *
+ *	update extent for allocated_but_not_recorded or
+ *	compressed extent;
+ *
+ * parameter:
+ *	nxad	- new XAD;
+ *		logical extent of the specified XAD must be completely
+ *		contained by an existing XAD;
+ */
+int xtUpdate(tid_t tid, struct inode *ip, xad_t * nxad)
+{				/* new XAD */
+	int rc = 0;
+	int cmp;
+	struct metapage *mp;	/* meta-page buffer */
+	xtpage_t *p;		/* base B+-tree index page */
+	s64 bn;
+	int index0, index, newindex, nextindex;
+	struct btstack btstack;	/* traverse stack */
+	struct xtsplit split;	/* split information */
+	xad_t *xad, *lxad, *rxad;
+	int xflag;
+	s64 nxoff, xoff;
+	int nxlen, xlen, lxlen, rxlen;
+	s64 nxaddr, xaddr;
+	struct tlock *tlck;
+	struct xtlock *xtlck = NULL;
+	int newpage = 0;
+
+	/* there must exist extent to be tailgated */
+	nxoff = offsetXAD(nxad);
+	nxlen = lengthXAD(nxad);
+	nxaddr = addressXAD(nxad);
+
+	if ((rc = xtSearch(ip, nxoff, NULL, &cmp, &btstack, XT_INSERT)))
+		return rc;
+
+	/* retrieve search result */
+	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index0);
+
+	if (cmp != 0) {
+		XT_PUTPAGE(mp);
+		jfs_error(ip->i_sb, "Could not find extent\n");
+		return -EIO;
+	}
+
+	BT_MARK_DIRTY(mp, ip);
+	/*
+	 * acquire tlock of the leaf page containing original entry
+	 */
+	if (!test_cflag(COMMIT_Nolink, ip)) {
+		tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
+		xtlck = (struct xtlock *) & tlck->lock;
+	}
+
+	xad = &p->xad[index0];
+	xflag = xad->flag;
+	xoff = offsetXAD(xad);
+	xlen = lengthXAD(xad);
+	xaddr = addressXAD(xad);
+
+	/* nXAD must be completely contained within XAD */
+	if ((xoff > nxoff) ||
+	    (nxoff + nxlen > xoff + xlen)) {
+		XT_PUTPAGE(mp);
+		jfs_error(ip->i_sb,
+			  "nXAD in not completely contained within XAD\n");
+		return -EIO;
+	}
+
+	index = index0;
+	newindex = index + 1;
+	nextindex = le16_to_cpu(p->header.nextindex);
+
+	if (xoff < nxoff)
+		goto coalesceRight;
+
+	/*
+	 * coalesce with left XAD
+	 */
+	/* is XAD first entry of page ? */
+	if (index == XTENTRYSTART)
+		goto replace;
+
+	/* is nXAD logically and physically contiguous with lXAD ? */
+	lxad = &p->xad[index - 1];
+	lxlen = lengthXAD(lxad);
+	if (!(lxad->flag & XAD_NOTRECORDED) &&
+	    (nxoff == offsetXAD(lxad) + lxlen) &&
+	    (nxaddr == addressXAD(lxad) + lxlen) &&
+	    (lxlen + nxlen < MAXXLEN)) {
+		/* extend right lXAD */
+		index0 = index - 1;
+		XADlength(lxad, lxlen + nxlen);
+
+		/* If we just merged two extents together, need to make sure the
+		 * right extent gets logged.  If the left one is marked XAD_NEW,
+		 * then we know it will be logged.  Otherwise, mark as
+		 * XAD_EXTENDED
+		 */
+		if (!(lxad->flag & XAD_NEW))
+			lxad->flag |= XAD_EXTENDED;
+
+		if (xlen > nxlen) {
+			/* truncate XAD */
+			XADoffset(xad, xoff + nxlen);
+			XADlength(xad, xlen - nxlen);
+			XADaddress(xad, xaddr + nxlen);
+			goto out;
+		} else {	/* (xlen == nxlen) */
+
+			/* remove XAD */
+			if (index < nextindex - 1)
+				memmove(&p->xad[index], &p->xad[index + 1],
+					(nextindex - index -
+					 1) << L2XTSLOTSIZE);
+
+			p->header.nextindex =
+			    cpu_to_le16(le16_to_cpu(p->header.nextindex) -
+					1);
+
+			index = index0;
+			newindex = index + 1;
+			nextindex = le16_to_cpu(p->header.nextindex);
+			xoff = nxoff = offsetXAD(lxad);
+			xlen = nxlen = lxlen + nxlen;
+			xaddr = nxaddr = addressXAD(lxad);
+			goto coalesceRight;
+		}
+	}
+
+	/*
+	 * replace XAD with nXAD
+	 */
+      replace:			/* (nxoff == xoff) */
+	if (nxlen == xlen) {
+		/* replace XAD with nXAD:recorded */
+		*xad = *nxad;
+		xad->flag = xflag & ~XAD_NOTRECORDED;
+
+		goto coalesceRight;
+	} else			/* (nxlen < xlen) */
+		goto updateLeft;
+
+	/*
+	 * coalesce with right XAD
+	 */
+      coalesceRight:		/* (xoff <= nxoff) */
+	/* is XAD last entry of page ? */
+	if (newindex == nextindex) {
+		if (xoff == nxoff)
+			goto out;
+		goto updateRight;
+	}
+
+	/* is nXAD logically and physically contiguous with rXAD ? */
+	rxad = &p->xad[index + 1];
+	rxlen = lengthXAD(rxad);
+	if (!(rxad->flag & XAD_NOTRECORDED) &&
+	    (nxoff + nxlen == offsetXAD(rxad)) &&
+	    (nxaddr + nxlen == addressXAD(rxad)) &&
+	    (rxlen + nxlen < MAXXLEN)) {
+		/* extend left rXAD */
+		XADoffset(rxad, nxoff);
+		XADlength(rxad, rxlen + nxlen);
+		XADaddress(rxad, nxaddr);
+
+		/* If we just merged two extents together, need to make sure
+		 * the left extent gets logged.  If the right one is marked
+		 * XAD_NEW, then we know it will be logged.  Otherwise, mark as
+		 * XAD_EXTENDED
+		 */
+		if (!(rxad->flag & XAD_NEW))
+			rxad->flag |= XAD_EXTENDED;
+
+		if (xlen > nxlen)
+			/* truncate XAD */
+			XADlength(xad, xlen - nxlen);
+		else {		/* (xlen == nxlen) */
+
+			/* remove XAD */
+			memmove(&p->xad[index], &p->xad[index + 1],
+				(nextindex - index - 1) << L2XTSLOTSIZE);
+
+			p->header.nextindex =
+			    cpu_to_le16(le16_to_cpu(p->header.nextindex) -
+					1);
+		}
+
+		goto out;
+	} else if (xoff == nxoff)
+		goto out;
+
+	if (xoff >= nxoff) {
+		XT_PUTPAGE(mp);
+		jfs_error(ip->i_sb, "xoff >= nxoff\n");
+		return -EIO;
+	}
+
+	/*
+	 * split XAD into (lXAD, nXAD):
+	 *
+	 *          |---nXAD--->
+	 * --|----------XAD----------|--
+	 *   |-lXAD-|
+	 */
+      updateRight:		/* (xoff < nxoff) */
+	/* truncate old XAD as lXAD:not_recorded */
+	xad = &p->xad[index];
+	XADlength(xad, nxoff - xoff);
+
+	/* insert nXAD:recorded */
+	if (nextindex == le16_to_cpu(p->header.maxentry)) {
+
+		/* xtSpliUp() unpins leaf pages */
+		split.mp = mp;
+		split.index = newindex;
+		split.flag = xflag & ~XAD_NOTRECORDED;
+		split.off = nxoff;
+		split.len = nxlen;
+		split.addr = nxaddr;
+		split.pxdlist = NULL;
+		if ((rc = xtSplitUp(tid, ip, &split, &btstack)))
+			return rc;
+
+		/* get back old page */
+		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+		if (rc)
+			return rc;
+		/*
+		 * if leaf root has been split, original root has been
+		 * copied to new child page, i.e., original entry now
+		 * resides on the new child page;
+		 */
+		if (p->header.flag & BT_INTERNAL) {
+			ASSERT(p->header.nextindex ==
+			       cpu_to_le16(XTENTRYSTART + 1));
+			xad = &p->xad[XTENTRYSTART];
+			bn = addressXAD(xad);
+			XT_PUTPAGE(mp);
+
+			/* get new child page */
+			XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+			if (rc)
+				return rc;
+
+			BT_MARK_DIRTY(mp, ip);
+			if (!test_cflag(COMMIT_Nolink, ip)) {
+				tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
+				xtlck = (struct xtlock *) & tlck->lock;
+			}
+		} else {
+			/* is nXAD on new page ? */
+			if (newindex >
+			    (le16_to_cpu(p->header.maxentry) >> 1)) {
+				newindex =
+				    newindex -
+				    le16_to_cpu(p->header.nextindex) +
+				    XTENTRYSTART;
+				newpage = 1;
+			}
+		}
+	} else {
+		/* if insert into middle, shift right remaining entries */
+		if (newindex < nextindex)
+			memmove(&p->xad[newindex + 1], &p->xad[newindex],
+				(nextindex - newindex) << L2XTSLOTSIZE);
+
+		/* insert the entry */
+		xad = &p->xad[newindex];
+		*xad = *nxad;
+		xad->flag = xflag & ~XAD_NOTRECORDED;
+
+		/* advance next available entry index. */
+		p->header.nextindex =
+		    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);
+	}
+
+	/*
+	 * does nXAD force 3-way split ?
+	 *
+	 *          |---nXAD--->|
+	 * --|----------XAD-------------|--
+	 *   |-lXAD-|           |-rXAD -|
+	 */
+	if (nxoff + nxlen == xoff + xlen)
+		goto out;
+
+	/* reorient nXAD as XAD for further split XAD into (nXAD, rXAD) */
+	if (newpage) {
+		/* close out old page */
+		if (!test_cflag(COMMIT_Nolink, ip)) {
+			xtlck->lwm.offset = (xtlck->lwm.offset) ?
+			    min(index0, (int)xtlck->lwm.offset) : index0;
+			xtlck->lwm.length =
+			    le16_to_cpu(p->header.nextindex) -
+			    xtlck->lwm.offset;
+		}
+
+		bn = le64_to_cpu(p->header.next);
+		XT_PUTPAGE(mp);
+
+		/* get new right page */
+		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+		if (rc)
+			return rc;
+
+		BT_MARK_DIRTY(mp, ip);
+		if (!test_cflag(COMMIT_Nolink, ip)) {
+			tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
+			xtlck = (struct xtlock *) & tlck->lock;
+		}
+
+		index0 = index = newindex;
+	} else
+		index++;
+
+	newindex = index + 1;
+	nextindex = le16_to_cpu(p->header.nextindex);
+	xlen = xlen - (nxoff - xoff);
+	xoff = nxoff;
+	xaddr = nxaddr;
+
+	/* recompute split pages */
+	if (nextindex == le16_to_cpu(p->header.maxentry)) {
+		XT_PUTPAGE(mp);
+
+		if ((rc = xtSearch(ip, nxoff, NULL, &cmp, &btstack, XT_INSERT)))
+			return rc;
+
+		/* retrieve search result */
+		XT_GETSEARCH(ip, btstack.top, bn, mp, p, index0);
+
+		if (cmp != 0) {
+			XT_PUTPAGE(mp);
+			jfs_error(ip->i_sb, "xtSearch failed\n");
+			return -EIO;
+		}
+
+		if (index0 != index) {
+			XT_PUTPAGE(mp);
+			jfs_error(ip->i_sb, "unexpected value of index\n");
+			return -EIO;
+		}
+	}
+
+	/*
+	 * split XAD into (nXAD, rXAD)
+	 *
+	 *          ---nXAD---|
+	 * --|----------XAD----------|--
+	 *                    |-rXAD-|
+	 */
+      updateLeft:		/* (nxoff == xoff) && (nxlen < xlen) */
+	/* update old XAD with nXAD:recorded */
+	xad = &p->xad[index];
+	*xad = *nxad;
+	xad->flag = xflag & ~XAD_NOTRECORDED;
+
+	/* insert rXAD:not_recorded */
+	xoff = xoff + nxlen;
+	xlen = xlen - nxlen;
+	xaddr = xaddr + nxlen;
+	if (nextindex == le16_to_cpu(p->header.maxentry)) {
+/*
+printf("xtUpdate.updateLeft.split p:0x%p\n", p);
+*/
+		/* xtSpliUp() unpins leaf pages */
+		split.mp = mp;
+		split.index = newindex;
+		split.flag = xflag;
+		split.off = xoff;
+		split.len = xlen;
+		split.addr = xaddr;
+		split.pxdlist = NULL;
+		if ((rc = xtSplitUp(tid, ip, &split, &btstack)))
+			return rc;
+
+		/* get back old page */
+		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+		if (rc)
+			return rc;
+
+		/*
+		 * if leaf root has been split, original root has been
+		 * copied to new child page, i.e., original entry now
+		 * resides on the new child page;
+		 */
+		if (p->header.flag & BT_INTERNAL) {
+			ASSERT(p->header.nextindex ==
+			       cpu_to_le16(XTENTRYSTART + 1));
+			xad = &p->xad[XTENTRYSTART];
+			bn = addressXAD(xad);
+			XT_PUTPAGE(mp);
+
+			/* get new child page */
+			XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+			if (rc)
+				return rc;
+
+			BT_MARK_DIRTY(mp, ip);
+			if (!test_cflag(COMMIT_Nolink, ip)) {
+				tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
+				xtlck = (struct xtlock *) & tlck->lock;
+			}
+		}
+	} else {
+		/* if insert into middle, shift right remaining entries */
+		if (newindex < nextindex)
+			memmove(&p->xad[newindex + 1], &p->xad[newindex],
+				(nextindex - newindex) << L2XTSLOTSIZE);
+
+		/* insert the entry */
+		xad = &p->xad[newindex];
+		XT_PUTENTRY(xad, xflag, xoff, xlen, xaddr);
+
+		/* advance next available entry index. */
+		p->header.nextindex =
+		    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);
+	}
+
+      out:
+	if (!test_cflag(COMMIT_Nolink, ip)) {
+		xtlck->lwm.offset = (xtlck->lwm.offset) ?
+		    min(index0, (int)xtlck->lwm.offset) : index0;
+		xtlck->lwm.length = le16_to_cpu(p->header.nextindex) -
+		    xtlck->lwm.offset;
+	}
+
+	/* unpin the leaf page */
+	XT_PUTPAGE(mp);
+
+	return rc;
+}
+
+
+/*
+ *	xtAppend()
+ *
+ * function: grow in append mode from contiguous region specified ;
+ *
+ * parameter:
+ *	tid		- transaction id;
+ *	ip		- file object;
+ *	xflag		- extent flag:
+ *	xoff		- extent offset;
+ *	maxblocks	- max extent length;
+ *	xlen		- extent length (in/out);
+ *	xaddrp		- extent address pointer (in/out):
+ *	flag		-
+ *
+ * return:
+ */
+int xtAppend(tid_t tid,		/* transaction id */
+	     struct inode *ip, int xflag, s64 xoff, s32 maxblocks,
+	     s32 * xlenp,	/* (in/out) */
+	     s64 * xaddrp,	/* (in/out) */
+	     int flag)
+{
+	int rc = 0;
+	struct metapage *mp;	/* meta-page buffer */
+	xtpage_t *p;		/* base B+-tree index page */
+	s64 bn, xaddr;
+	int index, nextindex;
+	struct btstack btstack;	/* traverse stack */
+	struct xtsplit split;	/* split information */
+	xad_t *xad;
+	int cmp;
+	struct tlock *tlck;
+	struct xtlock *xtlck;
+	int nsplit, nblocks, xlen;
+	struct pxdlist pxdlist;
+	pxd_t *pxd;
+	s64 next;
+
+	xaddr = *xaddrp;
+	xlen = *xlenp;
+	jfs_info("xtAppend: xoff:0x%lx maxblocks:%d xlen:%d xaddr:0x%lx",
+		 (ulong) xoff, maxblocks, xlen, (ulong) xaddr);
+
+	/*
+	 *	search for the entry location at which to insert:
+	 *
+	 * xtFastSearch() and xtSearch() both returns (leaf page
+	 * pinned, index at which to insert).
+	 * n.b. xtSearch() may return index of maxentry of
+	 * the full page.
+	 */
+	if ((rc = xtSearch(ip, xoff, &next, &cmp, &btstack, XT_INSERT)))
+		return rc;
+
+	/* retrieve search result */
+	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);
+
+	if (cmp == 0) {
+		rc = -EEXIST;
+		goto out;
+	}
+
+	if (next)
+		xlen = min(xlen, (int)(next - xoff));
+//insert:
+	/*
+	 *	insert entry for new extent
+	 */
+	xflag |= XAD_NEW;
+
+	/*
+	 *	if the leaf page is full, split the page and
+	 *	propagate up the router entry for the new page from split
+	 *
+	 * The xtSplitUp() will insert the entry and unpin the leaf page.
+	 */
+	nextindex = le16_to_cpu(p->header.nextindex);
+	if (nextindex < le16_to_cpu(p->header.maxentry))
+		goto insertLeaf;
+
+	/*
+	 * allocate new index blocks to cover index page split(s)
+	 */
+	nsplit = btstack.nsplit;
+	split.pxdlist = &pxdlist;
+	pxdlist.maxnpxd = pxdlist.npxd = 0;
+	pxd = &pxdlist.pxd[0];
+	nblocks = JFS_SBI(ip->i_sb)->nbperpage;
+	for (; nsplit > 0; nsplit--, pxd++, xaddr += nblocks, maxblocks -= nblocks) {
+		if ((rc = dbAllocBottomUp(ip, xaddr, (s64) nblocks)) == 0) {
+			PXDaddress(pxd, xaddr);
+			PXDlength(pxd, nblocks);
+
+			pxdlist.maxnpxd++;
+
+			continue;
+		}
+
+		/* undo allocation */
+
+		goto out;
+	}
+
+	xlen = min(xlen, maxblocks);
+
+	/*
+	 * allocate data extent requested
+	 */
+	if ((rc = dbAllocBottomUp(ip, xaddr, (s64) xlen)))
+		goto out;
+
+	split.mp = mp;
+	split.index = index;
+	split.flag = xflag;
+	split.off = xoff;
+	split.len = xlen;
+	split.addr = xaddr;
+	if ((rc = xtSplitUp(tid, ip, &split, &btstack))) {
+		/* undo data extent allocation */
+		dbFree(ip, *xaddrp, (s64) * xlenp);
+
+		return rc;
+	}
+
+	*xaddrp = xaddr;
+	*xlenp = xlen;
+	return 0;
+
+	/*
+	 *	insert the new entry into the leaf page
+	 */
+      insertLeaf:
+	/*
+	 * allocate data extent requested
+	 */
+	if ((rc = dbAllocBottomUp(ip, xaddr, (s64) xlen)))
+		goto out;
+
+	BT_MARK_DIRTY(mp, ip);
+	/*
+	 * acquire a transaction lock on the leaf page;
+	 *
+	 * action: xad insertion/extension;
+	 */
+	tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
+	xtlck = (struct xtlock *) & tlck->lock;
+
+	/* insert the new entry: mark the entry NEW */
+	xad = &p->xad[index];
+	XT_PUTENTRY(xad, xflag, xoff, xlen, xaddr);
+
+	/* advance next available entry index */
+	le16_add_cpu(&p->header.nextindex, 1);
+
+	xtlck->lwm.offset =
+	    (xtlck->lwm.offset) ? min(index,(int) xtlck->lwm.offset) : index;
+	xtlck->lwm.length = le16_to_cpu(p->header.nextindex) -
+	    xtlck->lwm.offset;
+
+	*xaddrp = xaddr;
+	*xlenp = xlen;
+
+      out:
+	/* unpin the leaf page */
+	XT_PUTPAGE(mp);
+
+	return rc;
+}
+
+/*
+ *	xtInitRoot()
+ *
+ * initialize file root (inline in inode)
+ */
+void xtInitRoot(tid_t tid, struct inode *ip)
+{
+	xtpage_t *p;
+
+	/*
+	 * acquire a transaction lock on the root
+	 *
+	 * action:
+	 */
+	txLock(tid, ip, (struct metapage *) &JFS_IP(ip)->bxflag,
+		      tlckXTREE | tlckNEW);
+	p = &JFS_IP(ip)->i_xtroot;
+
+	p->header.flag = DXD_INDEX | BT_ROOT | BT_LEAF;
+	p->header.nextindex = cpu_to_le16(XTENTRYSTART);
+
+	if (S_ISDIR(ip->i_mode))
+		p->header.maxentry = cpu_to_le16(XTROOTINITSLOT_DIR);
+	else {
+		p->header.maxentry = cpu_to_le16(XTROOTINITSLOT);
+		ip->i_size = 0;
+	}
+
+
+	return;
+}
+
+
+/*
+ * We can run into a deadlock truncating a file with a large number of
+ * xtree pages (large fragmented file).  A robust fix would entail a
+ * reservation system where we would reserve a number of metadata pages
+ * and tlocks which we would be guaranteed without a deadlock.  Without
+ * this, a partial fix is to limit number of metadata pages we will lock
+ * in a single transaction.  Currently we will truncate the file so that
+ * no more than 50 leaf pages will be locked.  The caller of xtTruncate
+ * will be responsible for ensuring that the current transaction gets
+ * committed, and that subsequent transactions are created to truncate
+ * the file further if needed.
+ */
+#define MAX_TRUNCATE_LEAVES 50
+
+/*
+ *	xtTruncate()
+ *
+ * function:
+ *	traverse for truncation logging backward bottom up;
+ *	terminate at the last extent entry at the current subtree
+ *	root page covering new down size.
+ *	truncation may occur within the last extent entry.
+ *
+ * parameter:
+ *	int		tid,
+ *	struct inode	*ip,
+ *	s64		newsize,
+ *	int		type)	{PWMAP, PMAP, WMAP; DELETE, TRUNCATE}
+ *
+ * return:
+ *
+ * note:
+ *	PWMAP:
+ *	 1. truncate (non-COMMIT_NOLINK file)
+ *	    by jfs_truncate() or jfs_open(O_TRUNC):
+ *	    xtree is updated;
+ *	 2. truncate index table of directory when last entry removed
+ *	map update via tlock at commit time;
+ *	PMAP:
+ *	 Call xtTruncate_pmap instead
+ *	WMAP:
+ *	 1. remove (free zero link count) on last reference release
+ *	    (pmap has been freed at commit zero link count);
+ *	 2. truncate (COMMIT_NOLINK file, i.e., tmp file):
+ *	    xtree is updated;
+ *	 map update directly at truncation time;
+ *
+ *	if (DELETE)
+ *		no LOG_NOREDOPAGE is required (NOREDOFILE is sufficient);
+ *	else if (TRUNCATE)
+ *		must write LOG_NOREDOPAGE for deleted index page;
+ *
+ * pages may already have been tlocked by anonymous transactions
+ * during file growth (i.e., write) before truncation;
+ *
+ * except last truncated entry, deleted entries remains as is
+ * in the page (nextindex is updated) for other use
+ * (e.g., log/update allocation map): this avoid copying the page
+ * info but delay free of pages;
+ *
+ */
+s64 xtTruncate(tid_t tid, struct inode *ip, s64 newsize, int flag)
+{
+	int rc = 0;
+	s64 teof;
+	struct metapage *mp;
+	xtpage_t *p;
+	s64 bn;
+	int index, nextindex;
+	xad_t *xad;
+	s64 xoff, xaddr;
+	int xlen, len, freexlen;
+	struct btstack btstack;
+	struct btframe *parent;
+	struct tblock *tblk = NULL;
+	struct tlock *tlck = NULL;
+	struct xtlock *xtlck = NULL;
+	struct xdlistlock xadlock;	/* maplock for COMMIT_WMAP */
+	struct pxd_lock *pxdlock;		/* maplock for COMMIT_WMAP */
+	s64 nfreed;
+	int freed, log;
+	int locked_leaves = 0;
+
+	/* save object truncation type */
+	if (tid) {
+		tblk = tid_to_tblock(tid);
+		tblk->xflag |= flag;
+	}
+
+	nfreed = 0;
+
+	flag &= COMMIT_MAP;
+	assert(flag != COMMIT_PMAP);
+
+	if (flag == COMMIT_PWMAP)
+		log = 1;
+	else {
+		log = 0;
+		xadlock.flag = mlckFREEXADLIST;
+		xadlock.index = 1;
+	}
+
+	/*
+	 * if the newsize is not an integral number of pages,
+	 * the file between newsize and next page boundary will
+	 * be cleared.
+	 * if truncating into a file hole, it will cause
+	 * a full block to be allocated for the logical block.
+	 */
+
+	/*
+	 * release page blocks of truncated region <teof, eof>
+	 *
+	 * free the data blocks from the leaf index blocks.
+	 * delete the parent index entries corresponding to
+	 * the freed child data/index blocks.
+	 * free the index blocks themselves which aren't needed
+	 * in new sized file.
+	 *
+	 * index blocks are updated only if the blocks are to be
+	 * retained in the new sized file.
+	 * if type is PMAP, the data and index pages are NOT
+	 * freed, and the data and index blocks are NOT freed
+	 * from working map.
+	 * (this will allow continued access of data/index of
+	 * temporary file (zerolink count file truncated to zero-length)).
+	 */
+	teof = (newsize + (JFS_SBI(ip->i_sb)->bsize - 1)) >>
+	    JFS_SBI(ip->i_sb)->l2bsize;
+
+	/* clear stack */
+	BT_CLR(&btstack);
+
+	/*
+	 * start with root
+	 *
+	 * root resides in the inode
+	 */
+	bn = 0;
+
+	/*
+	 * first access of each page:
+	 */
+      getPage:
+	XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+	if (rc)
+		return rc;
+
+	/* process entries backward from last index */
+	index = le16_to_cpu(p->header.nextindex) - 1;
+
+
+	/* Since this is the rightmost page at this level, and we may have
+	 * already freed a page that was formerly to the right, let's make
+	 * sure that the next pointer is zero.
+	 */
+	if (p->header.next) {
+		if (log)
+			/*
+			 * Make sure this change to the header is logged.
+			 * If we really truncate this leaf, the flag
+			 * will be changed to tlckTRUNCATE
+			 */
+			tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
+		BT_MARK_DIRTY(mp, ip);
+		p->header.next = 0;
+	}
+
+	if (p->header.flag & BT_INTERNAL)
+		goto getChild;
+
+	/*
+	 *	leaf page
+	 */
+	freed = 0;
+
+	/* does region covered by leaf page precede Teof ? */
+	xad = &p->xad[index];
+	xoff = offsetXAD(xad);
+	xlen = lengthXAD(xad);
+	if (teof >= xoff + xlen) {
+		XT_PUTPAGE(mp);
+		goto getParent;
+	}
+
+	/* (re)acquire tlock of the leaf page */
+	if (log) {
+		if (++locked_leaves > MAX_TRUNCATE_LEAVES) {
+			/*
+			 * We need to limit the size of the transaction
+			 * to avoid exhausting pagecache & tlocks
+			 */
+			XT_PUTPAGE(mp);
+			newsize = (xoff + xlen) << JFS_SBI(ip->i_sb)->l2bsize;
+			goto getParent;
+		}
+		tlck = txLock(tid, ip, mp, tlckXTREE);
+		tlck->type = tlckXTREE | tlckTRUNCATE;
+		xtlck = (struct xtlock *) & tlck->lock;
+		xtlck->hwm.offset = le16_to_cpu(p->header.nextindex) - 1;
+	}
+	BT_MARK_DIRTY(mp, ip);
+
+	/*
+	 * scan backward leaf page entries
+	 */
+	for (; index >= XTENTRYSTART; index--) {
+		xad = &p->xad[index];
+		xoff = offsetXAD(xad);
+		xlen = lengthXAD(xad);
+		xaddr = addressXAD(xad);
+
+		/*
+		 * The "data" for a directory is indexed by the block
+		 * device's address space.  This metadata must be invalidated
+		 * here
+		 */
+		if (S_ISDIR(ip->i_mode) && (teof == 0))
+			invalidate_xad_metapages(ip, *xad);
+		/*
+		 * entry beyond eof: continue scan of current page
+		 *          xad
+		 * ---|---=======------->
+		 *   eof
+		 */
+		if (teof < xoff) {
+			nfreed += xlen;
+			continue;
+		}
+
+		/*
+		 * (xoff <= teof): last entry to be deleted from page;
+		 * If other entries remain in page: keep and update the page.
+		 */
+
+		/*
+		 * eof == entry_start: delete the entry
+		 *           xad
+		 * -------|=======------->
+		 *       eof
+		 *
+		 */
+		if (teof == xoff) {
+			nfreed += xlen;
+
+			if (index == XTENTRYSTART)
+				break;
+
+			nextindex = index;
+		}
+		/*
+		 * eof within the entry: truncate the entry.
+		 *          xad
+		 * -------===|===------->
+		 *          eof
+		 */
+		else if (teof < xoff + xlen) {
+			/* update truncated entry */
+			len = teof - xoff;
+			freexlen = xlen - len;
+			XADlength(xad, len);
+
+			/* save pxd of truncated extent in tlck */
+			xaddr += len;
+			if (log) {	/* COMMIT_PWMAP */
+				xtlck->lwm.offset = (xtlck->lwm.offset) ?
+				    min(index, (int)xtlck->lwm.offset) : index;
+				xtlck->lwm.length = index + 1 -
+				    xtlck->lwm.offset;
+				xtlck->twm.offset = index;
+				pxdlock = (struct pxd_lock *) & xtlck->pxdlock;
+				pxdlock->flag = mlckFREEPXD;
+				PXDaddress(&pxdlock->pxd, xaddr);
+				PXDlength(&pxdlock->pxd, freexlen);
+			}
+			/* free truncated extent */
+			else {	/* COMMIT_WMAP */
+
+				pxdlock = (struct pxd_lock *) & xadlock;
+				pxdlock->flag = mlckFREEPXD;
+				PXDaddress(&pxdlock->pxd, xaddr);
+				PXDlength(&pxdlock->pxd, freexlen);
+				txFreeMap(ip, pxdlock, NULL, COMMIT_WMAP);
+
+				/* reset map lock */
+				xadlock.flag = mlckFREEXADLIST;
+			}
+
+			/* current entry is new last entry; */
+			nextindex = index + 1;
+
+			nfreed += freexlen;
+		}
+		/*
+		 * eof beyond the entry:
+		 *          xad
+		 * -------=======---|--->
+		 *                 eof
+		 */
+		else {		/* (xoff + xlen < teof) */
+
+			nextindex = index + 1;
+		}
+
+		if (nextindex < le16_to_cpu(p->header.nextindex)) {
+			if (!log) {	/* COMMIT_WAMP */
+				xadlock.xdlist = &p->xad[nextindex];
+				xadlock.count =
+				    le16_to_cpu(p->header.nextindex) -
+				    nextindex;
+				txFreeMap(ip, (struct maplock *) & xadlock,
+					  NULL, COMMIT_WMAP);
+			}
+			p->header.nextindex = cpu_to_le16(nextindex);
+		}
+
+		XT_PUTPAGE(mp);
+
+		/* assert(freed == 0); */
+		goto getParent;
+	}			/* end scan of leaf page entries */
+
+	freed = 1;
+
+	/*
+	 * leaf page become empty: free the page if type != PMAP
+	 */
+	if (log) {		/* COMMIT_PWMAP */
+		/* txCommit() with tlckFREE:
+		 * free data extents covered by leaf [XTENTRYSTART:hwm);
+		 * invalidate leaf if COMMIT_PWMAP;
+		 * if (TRUNCATE), will write LOG_NOREDOPAGE;
+		 */
+		tlck->type = tlckXTREE | tlckFREE;
+	} else {		/* COMMIT_WAMP */
+
+		/* free data extents covered by leaf */
+		xadlock.xdlist = &p->xad[XTENTRYSTART];
+		xadlock.count =
+		    le16_to_cpu(p->header.nextindex) - XTENTRYSTART;
+		txFreeMap(ip, (struct maplock *) & xadlock, NULL, COMMIT_WMAP);
+	}
+
+	if (p->header.flag & BT_ROOT) {
+		p->header.flag &= ~BT_INTERNAL;
+		p->header.flag |= BT_LEAF;
+		p->header.nextindex = cpu_to_le16(XTENTRYSTART);
+
+		XT_PUTPAGE(mp);	/* debug */
+		goto out;
+	} else {
+		if (log) {	/* COMMIT_PWMAP */
+			/* page will be invalidated at tx completion
+			 */
+			XT_PUTPAGE(mp);
+		} else {	/* COMMIT_WMAP */
+
+			if (mp->lid)
+				lid_to_tlock(mp->lid)->flag |= tlckFREELOCK;
+
+			/* invalidate empty leaf page */
+			discard_metapage(mp);
+		}
+	}
+
+	/*
+	 * the leaf page become empty: delete the parent entry
+	 * for the leaf page if the parent page is to be kept
+	 * in the new sized file.
+	 */
+
+	/*
+	 * go back up to the parent page
+	 */
+      getParent:
+	/* pop/restore parent entry for the current child page */
+	if ((parent = BT_POP(&btstack)) == NULL)
+		/* current page must have been root */
+		goto out;
+
+	/* get back the parent page */
+	bn = parent->bn;
+	XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+	if (rc)
+		return rc;
+
+	index = parent->index;
+
+	/*
+	 * child page was not empty:
+	 */
+	if (freed == 0) {
+		/* has any entry deleted from parent ? */
+		if (index < le16_to_cpu(p->header.nextindex) - 1) {
+			/* (re)acquire tlock on the parent page */
+			if (log) {	/* COMMIT_PWMAP */
+				/* txCommit() with tlckTRUNCATE:
+				 * free child extents covered by parent [);
+				 */
+				tlck = txLock(tid, ip, mp, tlckXTREE);
+				xtlck = (struct xtlock *) & tlck->lock;
+				if (!(tlck->type & tlckTRUNCATE)) {
+					xtlck->hwm.offset =
+					    le16_to_cpu(p->header.
+							nextindex) - 1;
+					tlck->type =
+					    tlckXTREE | tlckTRUNCATE;
+				}
+			} else {	/* COMMIT_WMAP */
+
+				/* free child extents covered by parent */
+				xadlock.xdlist = &p->xad[index + 1];
+				xadlock.count =
+				    le16_to_cpu(p->header.nextindex) -
+				    index - 1;
+				txFreeMap(ip, (struct maplock *) & xadlock,
+					  NULL, COMMIT_WMAP);
+			}
+			BT_MARK_DIRTY(mp, ip);
+
+			p->header.nextindex = cpu_to_le16(index + 1);
+		}
+		XT_PUTPAGE(mp);
+		goto getParent;
+	}
+
+	/*
+	 * child page was empty:
+	 */
+	nfreed += lengthXAD(&p->xad[index]);
+
+	/*
+	 * During working map update, child page's tlock must be handled
+	 * before parent's.  This is because the parent's tlock will cause
+	 * the child's disk space to be marked available in the wmap, so
+	 * it's important that the child page be released by that time.
+	 *
+	 * ToDo:  tlocks should be on doubly-linked list, so we can
+	 * quickly remove it and add it to the end.
+	 */
+
+	/*
+	 * Move parent page's tlock to the end of the tid's tlock list
+	 */
+	if (log && mp->lid && (tblk->last != mp->lid) &&
+	    lid_to_tlock(mp->lid)->tid) {
+		lid_t lid = mp->lid;
+		struct tlock *prev;
+
+		tlck = lid_to_tlock(lid);
+
+		if (tblk->next == lid)
+			tblk->next = tlck->next;
+		else {
+			for (prev = lid_to_tlock(tblk->next);
+			     prev->next != lid;
+			     prev = lid_to_tlock(prev->next)) {
+				assert(prev->next);
+			}
+			prev->next = tlck->next;
+		}
+		lid_to_tlock(tblk->last)->next = lid;
+		tlck->next = 0;
+		tblk->last = lid;
+	}
+
+	/*
+	 * parent page become empty: free the page
+	 */
+	if (index == XTENTRYSTART) {
+		if (log) {	/* COMMIT_PWMAP */
+			/* txCommit() with tlckFREE:
+			 * free child extents covered by parent;
+			 * invalidate parent if COMMIT_PWMAP;
+			 */
+			tlck = txLock(tid, ip, mp, tlckXTREE);
+			xtlck = (struct xtlock *) & tlck->lock;
+			xtlck->hwm.offset =
+			    le16_to_cpu(p->header.nextindex) - 1;
+			tlck->type = tlckXTREE | tlckFREE;
+		} else {	/* COMMIT_WMAP */
+
+			/* free child extents covered by parent */
+			xadlock.xdlist = &p->xad[XTENTRYSTART];
+			xadlock.count =
+			    le16_to_cpu(p->header.nextindex) -
+			    XTENTRYSTART;
+			txFreeMap(ip, (struct maplock *) & xadlock, NULL,
+				  COMMIT_WMAP);
+		}
+		BT_MARK_DIRTY(mp, ip);
+
+		if (p->header.flag & BT_ROOT) {
+			p->header.flag &= ~BT_INTERNAL;
+			p->header.flag |= BT_LEAF;
+			p->header.nextindex = cpu_to_le16(XTENTRYSTART);
+			if (le16_to_cpu(p->header.maxentry) == XTROOTMAXSLOT) {
+				/*
+				 * Shrink root down to allow inline
+				 * EA (otherwise fsck complains)
+				 */
+				p->header.maxentry =
+				    cpu_to_le16(XTROOTINITSLOT);
+				JFS_IP(ip)->mode2 |= INLINEEA;
+			}
+
+			XT_PUTPAGE(mp);	/* debug */
+			goto out;
+		} else {
+			if (log) {	/* COMMIT_PWMAP */
+				/* page will be invalidated at tx completion
+				 */
+				XT_PUTPAGE(mp);
+			} else {	/* COMMIT_WMAP */
+
+				if (mp->lid)
+					lid_to_tlock(mp->lid)->flag |=
+						tlckFREELOCK;
+
+				/* invalidate parent page */
+				discard_metapage(mp);
+			}
+
+			/* parent has become empty and freed:
+			 * go back up to its parent page
+			 */
+			/* freed = 1; */
+			goto getParent;
+		}
+	}
+	/*
+	 * parent page still has entries for front region;
+	 */
+	else {
+		/* try truncate region covered by preceding entry
+		 * (process backward)
+		 */
+		index--;
+
+		/* go back down to the child page corresponding
+		 * to the entry
+		 */
+		goto getChild;
+	}
+
+	/*
+	 *	internal page: go down to child page of current entry
+	 */
+      getChild:
+	/* save current parent entry for the child page */
+	if (BT_STACK_FULL(&btstack)) {
+		jfs_error(ip->i_sb, "stack overrun!\n");
+		XT_PUTPAGE(mp);
+		return -EIO;
+	}
+	BT_PUSH(&btstack, bn, index);
+
+	/* get child page */
+	xad = &p->xad[index];
+	bn = addressXAD(xad);
+
+	/*
+	 * first access of each internal entry:
+	 */
+	/* release parent page */
+	XT_PUTPAGE(mp);
+
+	/* process the child page */
+	goto getPage;
+
+      out:
+	/*
+	 * update file resource stat
+	 */
+	/* set size
+	 */
+	if (S_ISDIR(ip->i_mode) && !newsize)
+		ip->i_size = 1;	/* fsck hates zero-length directories */
+	else
+		ip->i_size = newsize;
+
+	/* update quota allocation to reflect freed blocks */
+	dquot_free_block(ip, nfreed);
+
+	/*
+	 * free tlock of invalidated pages
+	 */
+	if (flag == COMMIT_WMAP)
+		txFreelock(ip);
+
+	return newsize;
+}
+
+
+/*
+ *	xtTruncate_pmap()
+ *
+ * function:
+ *	Perform truncate to zero length for deleted file, leaving the
+ *	xtree and working map untouched.  This allows the file to
+ *	be accessed via open file handles, while the delete of the file
+ *	is committed to disk.
+ *
+ * parameter:
+ *	tid_t		tid,
+ *	struct inode	*ip,
+ *	s64		committed_size)
+ *
+ * return: new committed size
+ *
+ * note:
+ *
+ *	To avoid deadlock by holding too many transaction locks, the
+ *	truncation may be broken up into multiple transactions.
+ *	The committed_size keeps track of part of the file has been
+ *	freed from the pmaps.
+ */
+s64 xtTruncate_pmap(tid_t tid, struct inode *ip, s64 committed_size)
+{
+	s64 bn;
+	struct btstack btstack;
+	int cmp;
+	int index;
+	int locked_leaves = 0;
+	struct metapage *mp;
+	xtpage_t *p;
+	struct btframe *parent;
+	int rc;
+	struct tblock *tblk;
+	struct tlock *tlck = NULL;
+	xad_t *xad;
+	int xlen;
+	s64 xoff;
+	struct xtlock *xtlck = NULL;
+
+	/* save object truncation type */
+	tblk = tid_to_tblock(tid);
+	tblk->xflag |= COMMIT_PMAP;
+
+	/* clear stack */
+	BT_CLR(&btstack);
+
+	if (committed_size) {
+		xoff = (committed_size >> JFS_SBI(ip->i_sb)->l2bsize) - 1;
+		rc = xtSearch(ip, xoff, NULL, &cmp, &btstack, 0);
+		if (rc)
+			return rc;
+
+		XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);
+
+		if (cmp != 0) {
+			XT_PUTPAGE(mp);
+			jfs_error(ip->i_sb, "did not find extent\n");
+			return -EIO;
+		}
+	} else {
+		/*
+		 * start with root
+		 *
+		 * root resides in the inode
+		 */
+		bn = 0;
+
+		/*
+		 * first access of each page:
+		 */
+      getPage:
+		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+		if (rc)
+			return rc;
+
+		/* process entries backward from last index */
+		index = le16_to_cpu(p->header.nextindex) - 1;
+
+		if (p->header.flag & BT_INTERNAL)
+			goto getChild;
+	}
+
+	/*
+	 *	leaf page
+	 */
+
+	if (++locked_leaves > MAX_TRUNCATE_LEAVES) {
+		/*
+		 * We need to limit the size of the transaction
+		 * to avoid exhausting pagecache & tlocks
+		 */
+		xad = &p->xad[index];
+		xoff = offsetXAD(xad);
+		xlen = lengthXAD(xad);
+		XT_PUTPAGE(mp);
+		return (xoff + xlen) << JFS_SBI(ip->i_sb)->l2bsize;
+	}
+	tlck = txLock(tid, ip, mp, tlckXTREE);
+	tlck->type = tlckXTREE | tlckFREE;
+	xtlck = (struct xtlock *) & tlck->lock;
+	xtlck->hwm.offset = index;
+
+
+	XT_PUTPAGE(mp);
+
+	/*
+	 * go back up to the parent page
+	 */
+      getParent:
+	/* pop/restore parent entry for the current child page */
+	if ((parent = BT_POP(&btstack)) == NULL)
+		/* current page must have been root */
+		goto out;
+
+	/* get back the parent page */
+	bn = parent->bn;
+	XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
+	if (rc)
+		return rc;
+
+	index = parent->index;
+
+	/*
+	 * parent page become empty: free the page
+	 */
+	if (index == XTENTRYSTART) {
+		/* txCommit() with tlckFREE:
+		 * free child extents covered by parent;
+		 * invalidate parent if COMMIT_PWMAP;
+		 */
+		tlck = txLock(tid, ip, mp, tlckXTREE);
+		xtlck = (struct xtlock *) & tlck->lock;
+		xtlck->hwm.offset = le16_to_cpu(p->header.nextindex) - 1;
+		tlck->type = tlckXTREE | tlckFREE;
+
+		XT_PUTPAGE(mp);
+
+		if (p->header.flag & BT_ROOT) {
+
+			goto out;
+		} else {
+			goto getParent;
+		}
+	}
+	/*
+	 * parent page still has entries for front region;
+	 */
+	else
+		index--;
+	/*
+	 *	internal page: go down to child page of current entry
+	 */
+      getChild:
+	/* save current parent entry for the child page */
+	if (BT_STACK_FULL(&btstack)) {
+		jfs_error(ip->i_sb, "stack overrun!\n");
+		XT_PUTPAGE(mp);
+		return -EIO;
+	}
+	BT_PUSH(&btstack, bn, index);
+
+	/* get child page */
+	xad = &p->xad[index];
+	bn = addressXAD(xad);
+
+	/*
+	 * first access of each internal entry:
+	 */
+	/* release parent page */
+	XT_PUTPAGE(mp);
+
+	/* process the child page */
+	goto getPage;
+
+      out:
+
+	return 0;
+}
+
+#ifdef CONFIG_JFS_STATISTICS
+int jfs_xtstat_proc_show(struct seq_file *m, void *v)
+{
+	seq_printf(m,
+		       "JFS Xtree statistics\n"
+		       "====================\n"
+		       "searches = %d\n"
+		       "fast searches = %d\n"
+		       "splits = %d\n",
+		       xtStat.search,
+		       xtStat.fastSearch,
+		       xtStat.split);
+	return 0;
+}
+#endif