JFS: [3 of 6] implement get_index_page to replace some uses of read_index_page

# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
#	           ChangeSet	1.953.1.2 -> 1.953.1.3
#	  fs/jfs/jfs_dtree.c	1.9     -> 1.10   
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 03/01/29	[email protected]	1.953.1.3
# JFS: implement get_index_page to replace some uses of read_index_page
# 
# A recent change added the function read_index_page to replace calls to
# read_metapage() when accessing the directory index table.  However, we
# replaced both calls to read_metapage() and get_metapage() with the same
# function, but we really need two.  In addition to unnecesary disk reads,
# this problem caused an oops in __get_metapage().
# --------------------------------------------
#
diff -Nru a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
--- a/fs/jfs/jfs_dtree.c	Wed Feb 26 11:11:00 2003
+++ b/fs/jfs/jfs_dtree.c	Wed Feb 26 11:11:00 2003
@@ -222,6 +222,25 @@
 }
 
 /*
+ *	get_index_page()
+ *
+ *	Same as get_index_page(), but get's a new page without reading
+ */
+static struct metapage *get_index_page(struct inode *inode, s64 blkno)
+{
+	int rc;
+	s64 xaddr;
+	int xflag;
+	s32 xlen;
+
+	rc = xtLookup(inode, blkno, 1, &xflag, &xaddr, &xlen, 1);
+	if (rc || (xlen == 0))
+		return NULL;
+
+	return get_metapage(inode, xaddr, PSIZE, 1);
+}
+
+/*
  *	find_index()
  *
  *	Returns dtree page containing directory table entry for specified
@@ -390,7 +409,7 @@
 		ip->i_size = PSIZE;
 		ip->i_blocks += LBLK2PBLK(sb, sbi->nbperpage);
 
-		if ((mp = read_index_page(ip, 0)) == 0) {
+		if ((mp = get_index_page(ip, 0)) == 0) {
 			jfs_err("add_index: get_metapage failed!");
 			xtTruncate(tid, ip, 0, COMMIT_PWMAP);
 			return -1;
@@ -433,7 +452,7 @@
 		ip->i_size += PSIZE;
 		ip->i_blocks += LBLK2PBLK(sb, sbi->nbperpage);
 
-		if ((mp = read_index_page(ip, blkno)))
+		if ((mp = get_index_page(ip, blkno)))
 			memset(mp->data, 0, PSIZE);	/* Just looks better */
 		else
 			xtTruncate(tid, ip, offset, COMMIT_PWMAP);