ocfs2: Convenient access to an xattr bucket's block number.

The xattr code often wants to know the block number of an xattr bucket.
This is usually found by dereferencing the first bh hanging off of the
ocfs2_xattr_bucket structure.  Rather than do this all the time, let's
provide a nice little macro.  The idea is ripped from the ocfs2_path
code.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/ocfs2/xattr.c

@@ -154,6 +154,8 @@ static inline u16 ocfs2_xattr_max_xe_in_bucket(struct super_block *sb)
 	return len / sizeof(struct ocfs2_xattr_entry);
 }
 
+#define bucket_blkno(_b) ((_b)->bu_bhs[0]->b_blocknr)
+
 static inline const char *ocfs2_xattr_prefix(int name_index)
 {
 	struct xattr_handler *handler = NULL;
@@ -2290,7 +2292,7 @@ static int ocfs2_xattr_bucket_find(struct inode *inode,
 		 * If we have found the xattr enty, read all the blocks in
 		 * this bucket.
 		 */
-		ret = ocfs2_read_blocks(inode, xs->bucket.bu_bhs[0]->b_blocknr + 1,
+		ret = ocfs2_read_blocks(inode, bucket_blkno(&xs->bucket) + 1,
 					blk_per_bucket - 1, &xs->bucket.bu_bhs[1],
 					0);
 		if (ret) {
@@ -2300,7 +2302,7 @@ static int ocfs2_xattr_bucket_find(struct inode *inode,
 
 		xs->here = &xs->header->xh_entries[index];
 		mlog(0, "find xattr %s in bucket %llu, entry = %u\n", name,
-		     (unsigned long long)xs->bucket.bu_bhs[0]->b_blocknr, index);
+		     (unsigned long long)bucket_blkno(&xs->bucket), index);
 	} else
 		ret = -ENODATA;
 
@@ -2637,7 +2639,7 @@ static int ocfs2_xattr_update_xattr_search(struct inode *inode,
 	if (!xs->not_found) {
 		if (OCFS2_XATTR_BUCKET_SIZE != blocksize) {
 			ret = ocfs2_read_blocks(inode,
-					xs->bucket.bu_bhs[0]->b_blocknr + 1,
+					bucket_blkno(&xs->bucket) + 1,
 					blk_per_bucket - 1, &xs->bucket.bu_bhs[1],
 					0);
 			if (ret) {
@@ -2835,7 +2837,7 @@ static int ocfs2_defrag_xattr_bucket(struct inode *inode,
 	size_t end, offset, len, value_len;
 	struct ocfs2_xattr_header *xh;
 	char *entries, *buf, *bucket_buf = NULL;
-	u64 blkno = bucket->bu_bhs[0]->b_blocknr;
+	u64 blkno = bucket_blkno(bucket);
 	u16 blk_per_bucket = ocfs2_blocks_per_xattr_bucket(inode->i_sb);
 	u16 xh_free_start;
 	size_t blocksize = inode->i_sb->s_blocksize;
@@ -4124,11 +4126,11 @@ static int ocfs2_xattr_set_entry_in_bucket(struct inode *inode,
 
 	mlog(0, "Set xattr entry len = %lu index = %d in bucket %llu\n",
 	     (unsigned long)xi->value_len, xi->name_index,
-	     (unsigned long long)xs->bucket.bu_bhs[0]->b_blocknr);
+	     (unsigned long long)bucket_blkno(&xs->bucket));
 
 	if (!xs->bucket.bu_bhs[1]) {
 		ret = ocfs2_read_blocks(inode,
-					xs->bucket.bu_bhs[0]->b_blocknr + 1,
+					bucket_blkno(&xs->bucket) + 1,
 					blk_per_bucket - 1, &xs->bucket.bu_bhs[1],
 					0);
 		if (ret) {
@@ -4540,7 +4542,7 @@ static int ocfs2_check_xattr_bucket_collision(struct inode *inode,
 	    xh->xh_entries[0].xe_name_hash) {
 		mlog(ML_ERROR, "Too much hash collision in xattr bucket %llu, "
 		     "hash = %u\n",
-		     (unsigned long long)bucket->bu_bhs[0]->b_blocknr,
+		     (unsigned long long)bucket_blkno(bucket),
 		     le32_to_cpu(xh->xh_entries[0].xe_name_hash));
 		return -ENOSPC;
 	}
@@ -4574,7 +4576,7 @@ try_again:
 
 	mlog_bug_on_msg(header_size > blocksize, "bucket %llu has header size "
 			"of %u which exceed block size\n",
-			(unsigned long long)xs->bucket.bu_bhs[0]->b_blocknr,
+			(unsigned long long)bucket_blkno(&xs->bucket),
 			header_size);
 
 	if (xi->value && xi->value_len > OCFS2_XATTR_INLINE_SIZE)
@@ -4614,7 +4616,7 @@ try_again:
 	mlog(0, "xs->not_found = %d, in xattr bucket %llu: free = %d, "
 	     "need = %d, max_free = %d, xh_free_start = %u, xh_name_value_len ="
 	     " %u\n", xs->not_found,
-	     (unsigned long long)xs->bucket.bu_bhs[0]->b_blocknr,
+	     (unsigned long long)bucket_blkno(&xs->bucket),
 	     free, need, max_free, le16_to_cpu(xh->xh_free_start),
 	     le16_to_cpu(xh->xh_name_value_len));