[PATCH 17/21] implement generic xfs_btree_split

[PATCH 17/21] implement generic xfs_btree_split

[Christoph Hellwig]

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[-- Attachment #1: xfs-common-btree-split --]
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Make the btree split code generic.  Based on a patch from David Chinner
with lots of changes to follow the original btree implementations more
closely.  While this loses some of the generic helper routines for
inserting/moving/removing records it also solves some of the one off
bugs in the original code and makes it easier to verify.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: linux-2.6-xfs/fs/xfs/xfs_btree.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_btree.c	2008-07-29 16:48:45.000000000 +0200
+++ linux-2.6-xfs/fs/xfs/xfs_btree.c	2008-07-29 16:49:06.000000000 +0200
@@ -844,6 +844,48 @@ xfs_btree_get_sibling(
 	}
 }
 
+STATIC void
+xfs_btree_set_sibling(
+	struct xfs_btree_cur	*cur,
+	struct xfs_btree_block	*block,
+	union xfs_btree_ptr	*ptr,
+	int			lr)
+{
+	ASSERT(lr == XFS_BB_LEFTSIB || lr == XFS_BB_RIGHTSIB);
+
+	if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
+		if (lr == XFS_BB_RIGHTSIB)
+			block->bb_u.l.bb_rightsib = ptr->l;
+		else
+			block->bb_u.l.bb_leftsib = ptr->l;
+	} else {
+		if (lr == XFS_BB_RIGHTSIB)
+			block->bb_u.s.bb_rightsib = ptr->s;
+		else
+			block->bb_u.s.bb_leftsib = ptr->s;
+	}
+}
+
+STATIC void
+xfs_btree_init_block(
+	struct xfs_btree_cur	*cur,
+	int			level,
+	int			numrecs,
+	struct xfs_btree_block	*new)	/* new block */
+{
+	new->bb_h.bb_magic = cpu_to_be32(xfs_magics[cur->bc_btnum]);
+	new->bb_h.bb_level = cpu_to_be16(level);
+	new->bb_h.bb_numrecs = cpu_to_be16(numrecs);
+
+	if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
+		new->bb_u.l.bb_leftsib = cpu_to_be64(NULLFSBLOCK);
+		new->bb_u.l.bb_rightsib = cpu_to_be64(NULLFSBLOCK);
+	} else {
+		new->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
+		new->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
+	}
+}
+
 /*
  * Return true if ptr is the last record in the btree and
  * we need to track updateѕ to this record.  The decision
@@ -880,6 +922,21 @@ xfs_btree_buf_to_block(
 	return XFS_BUF_TO_BLOCK(bp);
 }
 
+STATIC void
+xfs_btree_buf_to_ptr(
+	struct xfs_btree_cur	*cur,
+	struct xfs_buf		*bp,
+	union xfs_btree_ptr	*ptr)
+{
+	if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
+		ptr->l = cpu_to_be64(XFS_DADDR_TO_FSB(cur->bc_mp,
+					XFS_BUF_ADDR(bp)));
+	else {
+		ptr->s = cpu_to_be32(XFS_DADDR_TO_AGBNO(cur->bc_mp,
+					XFS_BUF_ADDR(bp)));
+	}
+}
+
 STATIC xfs_daddr_t
 xfs_btree_ptr_to_daddr(
 	struct xfs_btree_cur	*cur,
@@ -919,6 +976,31 @@ xfs_btree_set_refs(
 	}
 }
 
+STATIC int
+xfs_btree_get_buf_block(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_ptr	*ptr,
+	int			flags,
+	struct xfs_btree_block	**block,
+	struct xfs_buf		**bpp)
+{
+	struct xfs_mount	*mp = cur->bc_mp;
+	xfs_daddr_t		d;
+
+	/* need to sort out how callers deal with failures first */
+	ASSERT(!(flags & XFS_BUF_TRYLOCK));
+
+	d = xfs_btree_ptr_to_daddr(cur, ptr);
+	*bpp = xfs_trans_get_buf(cur->bc_tp, mp->m_ddev_targp, d,
+				 mp->m_bsize, flags);
+
+	ASSERT(*bpp);
+	ASSERT(!XFS_BUF_GETERROR(*bpp));
+
+	*block = XFS_BUF_TO_BLOCK(*bpp);
+	return 0;
+}
+
 /*
  * Read in the buffer at the given ptr and return the buffer and
  * the block pointer within the buffer.
@@ -1968,3 +2050,189 @@ error1:
 	xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
 	return error;
 }
+
+/*
+ * Split cur/level block in half.
+ * Return new block number and the key to its first
+ * record (to be inserted into parent).
+ */
+int						/* error */
+xfs_btree_split(
+	struct xfs_btree_cur	*cur,
+	int			level,
+	union xfs_btree_ptr	*ptrp,
+	union xfs_btree_key	*key,
+	struct xfs_btree_cur	**curp,
+	int			*stat)		/* success/failure */
+{
+	union xfs_btree_ptr	lptr;		/* left sibling block ptr */
+	struct xfs_buf		*lbp;		/* left buffer pointer */
+	struct xfs_btree_block	*left;		/* left btree block */
+	union xfs_btree_ptr	rptr;		/* right sibling block ptr */
+	struct xfs_buf		*rbp;		/* right buffer pointer */
+	struct xfs_btree_block	*right;		/* right btree block */
+	union xfs_btree_ptr	rrptr;		/* right-right sibling ptr */
+	struct xfs_buf		*rrbp;		/* right-right buffer pointer */
+	struct xfs_btree_block	*rrblock;	/* right-right btree block */
+	int			lrecs;
+	int			rrecs;
+	int			src_index;
+	int			error;		/* error return value */
+#ifdef DEBUG
+	int			i;
+#endif
+
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+	XFS_BTREE_TRACE_ARGIPK(cur, level, *ptrp, key);
+
+	XFS_BTREE_STATS_INC(cur, split);
+
+	/* Set up left block (current one). */
+	left = xfs_btree_get_block(cur, level, &lbp);
+
+#ifdef DEBUG
+	error = xfs_btree_check_block(cur, left, level, lbp);
+	if (error)
+		goto error0;
+#endif
+
+	xfs_btree_buf_to_ptr(cur, lbp, &lptr);
+
+	/* Allocate the new block. If we can't do it, we're toast. Give up. */
+	error = cur->bc_ops->alloc_block(cur, &lptr, &rptr, 1, stat);
+	if (error)
+		goto error0;
+	if (*stat == 0)
+		goto out0;
+	XFS_BTREE_STATS_INC(cur, alloc);
+
+	/* Set up the new block as "right". */
+	error = xfs_btree_get_buf_block(cur, &rptr, 0, &right, &rbp);
+	if (error)
+		goto error0;
+
+	/* Fill in the btree header for the new right block. */
+	xfs_btree_init_block(cur, be16_to_cpu(left->bb_h.bb_level), 0, right);
+
+	/*
+	 * Split the entries between the old and the new block evenly.
+	 * Make sure that if there's an odd number of entries now, that
+	 * each new block will have the same number of entries.
+	 */
+	lrecs = xfs_btree_get_numrecs(left);
+	rrecs = lrecs / 2;
+	if ((lrecs & 1) && cur->bc_ptrs[level] <= rrecs + 1)
+		rrecs++;
+	src_index = (lrecs - rrecs + 1);
+
+	XFS_BTREE_STATS_ADD(cur, moves, rrecs);
+
+	/*
+	 * Copy btree block entries from the left block over to the
+	 * new block, the right. Update the right block and log the
+	 * changes.
+	 */
+	if (level > 0) {
+		/* It's a non-leaf.  Move keys and pointers. */
+		union xfs_btree_key	*lkp;	/* left btree key */
+		union xfs_btree_ptr	*lpp;	/* left address pointer */
+		union xfs_btree_key	*rkp;	/* right btree key */
+		union xfs_btree_ptr	*rpp;	/* right address pointer */
+
+		lkp = cur->bc_ops->key_addr(cur, src_index, left);
+		lpp = cur->bc_ops->ptr_addr(cur, src_index, left);
+		rkp = cur->bc_ops->key_addr(cur, 1, right);
+		rpp = cur->bc_ops->ptr_addr(cur, 1, right);
+
+#ifdef DEBUG
+		for (i = src_index; i < rrecs; i++) {
+			error = xfs_btree_check_ptr(cur, lpp, i, level);
+			if (error)
+				goto error0;
+		}
+#endif
+
+		cur->bc_ops->copy_keys(cur, lkp, rkp, rrecs);
+		xfs_btree_copy_ptrs(cur, lpp, rpp, rrecs);
+
+		cur->bc_ops->log_keys(cur, rbp, 1, rrecs);
+		xfs_btree_log_ptrs(cur, rbp, 1, rrecs);
+
+		/* Grab the keys to the entries moved to the right block */
+		cur->bc_ops->copy_keys(cur, rkp, key, 1);
+	} else {
+		/* It's a leaf.  Move records.  */
+		union xfs_btree_rec	*lrp;	/* left record pointer */
+		union xfs_btree_rec	*rrp;	/* right record pointer */
+
+		lrp = cur->bc_ops->rec_addr(cur, src_index, left);
+		rrp = cur->bc_ops->rec_addr(cur, 1, right);
+
+		cur->bc_ops->copy_recs(cur, lrp, rrp, rrecs);
+		cur->bc_ops->log_recs(cur, rbp, 1, rrecs);
+
+		cur->bc_ops->init_key_from_rec(cur, key,
+			cur->bc_ops->rec_addr(cur, 1, right));
+	}
+
+
+	/*
+	 * Find the left block number by looking in the buffer.
+	 * Adjust numrecs, sibling pointers.
+	 */
+	xfs_btree_get_sibling(cur, left, &rrptr, XFS_BB_RIGHTSIB);
+	xfs_btree_set_sibling(cur, right, &rrptr, XFS_BB_RIGHTSIB);
+	xfs_btree_set_sibling(cur, right, &lptr, XFS_BB_LEFTSIB);
+	xfs_btree_set_sibling(cur, left, &rptr, XFS_BB_RIGHTSIB);
+
+	lrecs -= rrecs;
+	xfs_btree_set_numrecs(left, lrecs);
+	xfs_btree_set_numrecs(right, xfs_btree_get_numrecs(right) + rrecs);
+
+	xfs_btree_log_block(cur, rbp, XFS_BB_ALL_BITS);
+	xfs_btree_log_block(cur, lbp, XFS_BB_NUMRECS | XFS_BB_RIGHTSIB);
+
+	/*
+	 * If there's a block to the new block's right, make that block
+	 * point back to right instead of to left.
+	 */
+	if (!xfs_btree_ptr_is_null(cur, &rrptr)) {
+		error = xfs_btree_read_buf_block(cur, &rrptr, level,
+							0, &rrblock, &rrbp);
+		if (error)
+			goto error0;
+		xfs_btree_set_sibling(cur, rrblock, &rptr, XFS_BB_LEFTSIB);
+		xfs_btree_log_block(cur, rrbp, XFS_BB_LEFTSIB);
+	}
+	/*
+	 * If the cursor is really in the right block, move it there.
+	 * If it's just pointing past the last entry in left, then we'll
+	 * insert there, so don't change anything in that case.
+	 */
+	if (cur->bc_ptrs[level] > lrecs + 1) {
+		xfs_btree_setbuf(cur, level, rbp);
+		cur->bc_ptrs[level] -= lrecs;
+	}
+	/*
+	 * If there are more levels, we'll need another cursor which refers
+	 * the right block, no matter where this cursor was.
+	 */
+	if (level + 1 < cur->bc_nlevels) {
+		error = xfs_btree_dup_cursor(cur, curp);
+		if (error)
+			goto error0;
+		(*curp)->bc_ptrs[level + 1]++;
+	}
+	*ptrp = rptr;
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+	*stat = 1;
+	return 0;
+out0:
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+	*stat = 0;
+	return 0;
+
+error0:
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+	return error;
+}
Index: linux-2.6-xfs/fs/xfs/xfs_btree.h
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_btree.h	2008-07-29 16:48:45.000000000 +0200
+++ linux-2.6-xfs/fs/xfs/xfs_btree.h	2008-07-29 16:48:46.000000000 +0200
@@ -191,6 +191,12 @@ struct xfs_btree_ops {
 	/* get inode rooted btree root */
 	struct xfs_btree_block *(*get_root_from_inode)(struct xfs_btree_cur *);
 
+	/* block allocation / freeing */
+	int	(*alloc_block)(struct xfs_btree_cur *cur,
+			       union xfs_btree_ptr *sbno,
+			       union xfs_btree_ptr *nbno,
+			       int length, int *stat);
+
 	/* updated last record information */
 	void	(*update_lastrec)(struct xfs_btree_cur *,
 				  struct xfs_btree_block *,
@@ -577,6 +583,8 @@ int xfs_btree_updkey(struct xfs_btree_cu
 int xfs_btree_update(struct xfs_btree_cur *, union xfs_btree_rec *);
 int xfs_btree_lshift(struct xfs_btree_cur *, int, int *);
 int xfs_btree_rshift(struct xfs_btree_cur *, int, int *);
+int xfs_btree_split(struct xfs_btree_cur *, int, union xfs_btree_ptr *,
+		union xfs_btree_key *, struct xfs_btree_cur **, int *);
 
 
 /*
Index: linux-2.6-xfs/fs/xfs/xfs_alloc_btree.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_alloc_btree.c	2008-07-29 16:48:45.000000000 +0200
+++ linux-2.6-xfs/fs/xfs/xfs_alloc_btree.c	2008-07-29 16:48:46.000000000 +0200
@@ -53,8 +53,6 @@ STATIC void xfs_allocbt_log_recs(xfs_btr
 #define xfs_alloc_log_recs(c, b, i, j) \
 	xfs_allocbt_log_recs(c, b, i, j)
 STATIC int xfs_alloc_newroot(xfs_btree_cur_t *, int *);
-STATIC int xfs_alloc_split(xfs_btree_cur_t *, int, xfs_agblock_t *,
-		xfs_alloc_key_t *, xfs_btree_cur_t **, int *);
 
 /*
  * Internal functions.
@@ -700,15 +698,18 @@ xfs_alloc_insrec(
 			if (i)
 				optr = ptr = cur->bc_ptrs[level];
 			else {
+				union xfs_btree_ptr bno = { .s = cpu_to_be32(nbno) };
 				/*
 				 * Next, try splitting the current block in
 				 * half. If this works we have to re-set our
 				 * variables because we could be in a
 				 * different block now.
 				 */
-				if ((error = xfs_alloc_split(cur, level, &nbno,
-						&nkey, &ncur, &i)))
+				if ((error = xfs_btree_split(cur, level, &bno,
+						(union xfs_btree_key *)&nkey,
+						&ncur, &i)))
 					return error;
+				nbno = be32_to_cpu(bno.s);
 				if (i) {
 					bp = cur->bc_bufs[level];
 					block = XFS_BUF_TO_ALLOC_BLOCK(bp);
@@ -1037,160 +1038,6 @@ xfs_alloc_newroot(
 	return 0;
 }
 
-/*
- * Split cur/level block in half.
- * Return new block number and its first record (to be inserted into parent).
- */
-STATIC int				/* error */
-xfs_alloc_split(
-	xfs_btree_cur_t		*cur,	/* btree cursor */
-	int			level,	/* level to split */
-	xfs_agblock_t		*bnop,	/* output: block number allocated */
-	xfs_alloc_key_t		*keyp,	/* output: first key of new block */
-	xfs_btree_cur_t		**curp,	/* output: new cursor */
-	int			*stat)	/* success/failure */
-{
-	int			error;	/* error return value */
-	int			i;	/* loop index/record number */
-	xfs_agblock_t		lbno;	/* left (current) block number */
-	xfs_buf_t		*lbp;	/* buffer for left block */
-	xfs_alloc_block_t	*left;	/* left (current) btree block */
-	xfs_agblock_t		rbno;	/* right (new) block number */
-	xfs_buf_t		*rbp;	/* buffer for right block */
-	xfs_alloc_block_t	*right;	/* right (new) btree block */
-
-	/*
-	 * Allocate the new block from the freelist.
-	 * If we can't do it, we're toast.  Give up.
-	 */
-	error = xfs_alloc_get_freelist(cur->bc_tp,
-					 cur->bc_private.a.agbp, &rbno, 1);
-	if (error)
-		return error;
-	if (rbno == NULLAGBLOCK) {
-		*stat = 0;
-		return 0;
-	}
-	xfs_trans_agbtree_delta(cur->bc_tp, 1);
-	rbp = xfs_btree_get_bufs(cur->bc_mp, cur->bc_tp, cur->bc_private.a.agno,
-		rbno, 0);
-	/*
-	 * Set up the new block as "right".
-	 */
-	right = XFS_BUF_TO_ALLOC_BLOCK(rbp);
-	/*
-	 * "Left" is the current (according to the cursor) block.
-	 */
-	lbp = cur->bc_bufs[level];
-	left = XFS_BUF_TO_ALLOC_BLOCK(lbp);
-#ifdef DEBUG
-	if ((error = xfs_btree_check_sblock(cur, left, level, lbp)))
-		return error;
-#endif
-	/*
-	 * Fill in the btree header for the new block.
-	 */
-	right->bb_magic = cpu_to_be32(xfs_magics[cur->bc_btnum]);
-	right->bb_level = left->bb_level;
-	right->bb_numrecs = cpu_to_be16(be16_to_cpu(left->bb_numrecs) / 2);
-	/*
-	 * Make sure that if there's an odd number of entries now, that
-	 * each new block will have the same number of entries.
-	 */
-	if ((be16_to_cpu(left->bb_numrecs) & 1) &&
-	    cur->bc_ptrs[level] <= be16_to_cpu(right->bb_numrecs) + 1)
-		be16_add(&right->bb_numrecs, 1);
-	i = be16_to_cpu(left->bb_numrecs) - be16_to_cpu(right->bb_numrecs) + 1;
-	/*
-	 * For non-leaf blocks, copy keys and addresses over to the new block.
-	 */
-	if (level > 0) {
-		xfs_alloc_key_t	*lkp;	/* left btree key pointer */
-		xfs_alloc_ptr_t	*lpp;	/* left btree address pointer */
-		xfs_alloc_key_t	*rkp;	/* right btree key pointer */
-		xfs_alloc_ptr_t	*rpp;	/* right btree address pointer */
-
-		lkp = XFS_ALLOC_KEY_ADDR(left, i, cur);
-		lpp = XFS_ALLOC_PTR_ADDR(left, i, cur);
-		rkp = XFS_ALLOC_KEY_ADDR(right, 1, cur);
-		rpp = XFS_ALLOC_PTR_ADDR(right, 1, cur);
-#ifdef DEBUG
-		for (i = 0; i < be16_to_cpu(right->bb_numrecs); i++) {
-			if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(lpp[i]), level)))
-				return error;
-		}
-#endif
-		memcpy(rkp, lkp, be16_to_cpu(right->bb_numrecs) * sizeof(*rkp));
-		memcpy(rpp, lpp, be16_to_cpu(right->bb_numrecs) * sizeof(*rpp));
-		xfs_alloc_log_keys(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-		xfs_alloc_log_ptrs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-		*keyp = *rkp;
-	}
-	/*
-	 * For leaf blocks, copy records over to the new block.
-	 */
-	else {
-		xfs_alloc_rec_t	*lrp;	/* left btree record pointer */
-		xfs_alloc_rec_t	*rrp;	/* right btree record pointer */
-
-		lrp = XFS_ALLOC_REC_ADDR(left, i, cur);
-		rrp = XFS_ALLOC_REC_ADDR(right, 1, cur);
-		memcpy(rrp, lrp, be16_to_cpu(right->bb_numrecs) * sizeof(*rrp));
-		xfs_alloc_log_recs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-		keyp->ar_startblock = rrp->ar_startblock;
-		keyp->ar_blockcount = rrp->ar_blockcount;
-	}
-	/*
-	 * Find the left block number by looking in the buffer.
-	 * Adjust numrecs, sibling pointers.
-	 */
-	lbno = XFS_DADDR_TO_AGBNO(cur->bc_mp, XFS_BUF_ADDR(lbp));
-	be16_add(&left->bb_numrecs, -(be16_to_cpu(right->bb_numrecs)));
-	right->bb_rightsib = left->bb_rightsib;
-	left->bb_rightsib = cpu_to_be32(rbno);
-	right->bb_leftsib = cpu_to_be32(lbno);
-	xfs_alloc_log_block(cur->bc_tp, rbp, XFS_BB_ALL_BITS);
-	xfs_alloc_log_block(cur->bc_tp, lbp, XFS_BB_NUMRECS | XFS_BB_RIGHTSIB);
-	/*
-	 * If there's a block to the new block's right, make that block
-	 * point back to right instead of to left.
-	 */
-	if (be32_to_cpu(right->bb_rightsib) != NULLAGBLOCK) {
-		xfs_alloc_block_t	*rrblock;	/* rr btree block */
-		xfs_buf_t		*rrbp;		/* buffer for rrblock */
-
-		if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
-				cur->bc_private.a.agno, be32_to_cpu(right->bb_rightsib), 0,
-				&rrbp, XFS_ALLOC_BTREE_REF)))
-			return error;
-		rrblock = XFS_BUF_TO_ALLOC_BLOCK(rrbp);
-		if ((error = xfs_btree_check_sblock(cur, rrblock, level, rrbp)))
-			return error;
-		rrblock->bb_leftsib = cpu_to_be32(rbno);
-		xfs_alloc_log_block(cur->bc_tp, rrbp, XFS_BB_LEFTSIB);
-	}
-	/*
-	 * If the cursor is really in the right block, move it there.
-	 * If it's just pointing past the last entry in left, then we'll
-	 * insert there, so don't change anything in that case.
-	 */
-	if (cur->bc_ptrs[level] > be16_to_cpu(left->bb_numrecs) + 1) {
-		xfs_btree_setbuf(cur, level, rbp);
-		cur->bc_ptrs[level] -= be16_to_cpu(left->bb_numrecs);
-	}
-	/*
-	 * If there are more levels, we'll need another cursor which refers to
-	 * the right block, no matter where this cursor was.
-	 */
-	if (level + 1 < cur->bc_nlevels) {
-		if ((error = xfs_btree_dup_cursor(cur, curp)))
-			return error;
-		(*curp)->bc_ptrs[level + 1]++;
-	}
-	*bnop = rbno;
-	*stat = 1;
-	return 0;
-}
 
 /*
  * Externally visible routines.
@@ -1344,6 +1191,41 @@ xfs_allocbt_dup_cursor(
 			cur->bc_btnum);
 }
 
+STATIC int
+xfs_allocbt_alloc_block(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_ptr	*start,
+	union xfs_btree_ptr	*new,
+	int			length,
+	int			*stat)
+{
+	int			error;
+	xfs_agblock_t		bno;
+
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+
+	/* Allocate the new block from the freelist. If we can't, give up.  */
+	error = xfs_alloc_get_freelist(cur->bc_tp, cur->bc_private.a.agbp,
+				       &bno, 1);
+	if (error) {
+		XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+		return error;
+	}
+
+	if (bno == NULLAGBLOCK) {
+		XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+		*stat = 0;
+		return 0;
+	}
+
+	xfs_trans_agbtree_delta(cur->bc_tp, 1);
+	new->s = cpu_to_be32(bno);
+
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+	*stat = 1;
+	return 0;
+}
+
 /*
  * Update the longest extent in the AGF
  */
@@ -1680,6 +1562,7 @@ xfs_allocbt_trace_record(
 
 static const struct xfs_btree_ops xfs_allocbt_ops = {
 	.dup_cursor		= xfs_allocbt_dup_cursor,
+	.alloc_block		= xfs_allocbt_alloc_block,
 	.update_lastrec		= xfs_allocbt_update_lastrec,
 	.get_maxrecs		= xfs_allocbt_get_maxrecs,
 	.init_key_from_rec	= xfs_allocbt_init_key_from_rec,
Index: linux-2.6-xfs/fs/xfs/xfs_ialloc_btree.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_ialloc_btree.c	2008-07-29 16:48:45.000000000 +0200
+++ linux-2.6-xfs/fs/xfs/xfs_ialloc_btree.c	2008-07-29 16:48:46.000000000 +0200
@@ -45,8 +45,6 @@ STATIC void xfs_inobt_log_keys(xfs_btree
 STATIC void xfs_inobt_log_ptrs(xfs_btree_cur_t *, xfs_buf_t *, int, int);
 STATIC void xfs_inobt_log_recs(xfs_btree_cur_t *, xfs_buf_t *, int, int);
 STATIC int xfs_inobt_newroot(xfs_btree_cur_t *, int *);
-STATIC int xfs_inobt_split(xfs_btree_cur_t *, int, xfs_agblock_t *,
-		xfs_inobt_key_t *, xfs_btree_cur_t **, int *);
 
 /*
  * Single level of the xfs_inobt_delete record deletion routine.
@@ -621,15 +619,18 @@ xfs_inobt_insrec(
 			if (i) {
 				optr = ptr = cur->bc_ptrs[level];
 			} else {
+				union xfs_btree_ptr bno = { .s = cpu_to_be32(nbno) };
 				/*
 				 * Next, try splitting the current block
 				 * in half. If this works we have to
 				 * re-set our variables because
 				 * we could be in a different block now.
 				 */
-				if ((error = xfs_inobt_split(cur, level, &nbno,
-						&nkey, &ncur, &i)))
+				if ((error = xfs_btree_split(cur, level, &bno,
+						(union xfs_btree_key *)&nkey,
+						&ncur, &i)))
 					return error;
+				nbno = be32_to_cpu(bno.s);
 				if (i) {
 					bp = cur->bc_bufs[level];
 					block = XFS_BUF_TO_INOBT_BLOCK(bp);
@@ -930,165 +931,6 @@ xfs_inobt_newroot(
 }
 
 /*
- * Split cur/level block in half.
- * Return new block number and its first record (to be inserted into parent).
- */
-STATIC int				/* error */
-xfs_inobt_split(
-	xfs_btree_cur_t		*cur,	/* btree cursor */
-	int			level,	/* level to split */
-	xfs_agblock_t		*bnop,	/* output: block number allocated */
-	xfs_inobt_key_t		*keyp,	/* output: first key of new block */
-	xfs_btree_cur_t		**curp,	/* output: new cursor */
-	int			*stat)	/* success/failure */
-{
-	xfs_alloc_arg_t		args;	/* allocation argument structure */
-	int			error;	/* error return value */
-	int			i;	/* loop index/record number */
-	xfs_agblock_t		lbno;	/* left (current) block number */
-	xfs_buf_t		*lbp;	/* buffer for left block */
-	xfs_inobt_block_t	*left;	/* left (current) btree block */
-	xfs_inobt_key_t		*lkp;	/* left btree key pointer */
-	xfs_inobt_ptr_t		*lpp;	/* left btree address pointer */
-	xfs_inobt_rec_t		*lrp;	/* left btree record pointer */
-	xfs_buf_t		*rbp;	/* buffer for right block */
-	xfs_inobt_block_t	*right;	/* right (new) btree block */
-	xfs_inobt_key_t		*rkp;	/* right btree key pointer */
-	xfs_inobt_ptr_t		*rpp;	/* right btree address pointer */
-	xfs_inobt_rec_t		*rrp;	/* right btree record pointer */
-
-	/*
-	 * Set up left block (current one).
-	 */
-	lbp = cur->bc_bufs[level];
-	args.tp = cur->bc_tp;
-	args.mp = cur->bc_mp;
-	lbno = XFS_DADDR_TO_AGBNO(args.mp, XFS_BUF_ADDR(lbp));
-	/*
-	 * Allocate the new block.
-	 * If we can't do it, we're toast.  Give up.
-	 */
-	args.fsbno = XFS_AGB_TO_FSB(args.mp, cur->bc_private.a.agno, lbno);
-	args.mod = args.minleft = args.alignment = args.total = args.wasdel =
-		args.isfl = args.userdata = args.minalignslop = 0;
-	args.minlen = args.maxlen = args.prod = 1;
-	args.type = XFS_ALLOCTYPE_NEAR_BNO;
-	if ((error = xfs_alloc_vextent(&args)))
-		return error;
-	if (args.fsbno == NULLFSBLOCK) {
-		*stat = 0;
-		return 0;
-	}
-	ASSERT(args.len == 1);
-	rbp = xfs_btree_get_bufs(args.mp, args.tp, args.agno, args.agbno, 0);
-	/*
-	 * Set up the new block as "right".
-	 */
-	right = XFS_BUF_TO_INOBT_BLOCK(rbp);
-	/*
-	 * "Left" is the current (according to the cursor) block.
-	 */
-	left = XFS_BUF_TO_INOBT_BLOCK(lbp);
-#ifdef DEBUG
-	if ((error = xfs_btree_check_sblock(cur, left, level, lbp)))
-		return error;
-#endif
-	/*
-	 * Fill in the btree header for the new block.
-	 */
-	right->bb_magic = cpu_to_be32(xfs_magics[cur->bc_btnum]);
-	right->bb_level = left->bb_level;
-	right->bb_numrecs = cpu_to_be16(be16_to_cpu(left->bb_numrecs) / 2);
-	/*
-	 * Make sure that if there's an odd number of entries now, that
-	 * each new block will have the same number of entries.
-	 */
-	if ((be16_to_cpu(left->bb_numrecs) & 1) &&
-	    cur->bc_ptrs[level] <= be16_to_cpu(right->bb_numrecs) + 1)
-		be16_add(&right->bb_numrecs, 1);
-	i = be16_to_cpu(left->bb_numrecs) - be16_to_cpu(right->bb_numrecs) + 1;
-	/*
-	 * For non-leaf blocks, copy keys and addresses over to the new block.
-	 */
-	if (level > 0) {
-		lkp = XFS_INOBT_KEY_ADDR(left, i, cur);
-		lpp = XFS_INOBT_PTR_ADDR(left, i, cur);
-		rkp = XFS_INOBT_KEY_ADDR(right, 1, cur);
-		rpp = XFS_INOBT_PTR_ADDR(right, 1, cur);
-#ifdef DEBUG
-		for (i = 0; i < be16_to_cpu(right->bb_numrecs); i++) {
-			if ((error = xfs_btree_check_sptr(cur, be32_to_cpu(lpp[i]), level)))
-				return error;
-		}
-#endif
-		memcpy(rkp, lkp, be16_to_cpu(right->bb_numrecs) * sizeof(*rkp));
-		memcpy(rpp, lpp, be16_to_cpu(right->bb_numrecs) * sizeof(*rpp));
-		xfs_inobt_log_keys(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-		xfs_inobt_log_ptrs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-		*keyp = *rkp;
-	}
-	/*
-	 * For leaf blocks, copy records over to the new block.
-	 */
-	else {
-		lrp = XFS_INOBT_REC_ADDR(left, i, cur);
-		rrp = XFS_INOBT_REC_ADDR(right, 1, cur);
-		memcpy(rrp, lrp, be16_to_cpu(right->bb_numrecs) * sizeof(*rrp));
-		xfs_inobt_log_recs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-		keyp->ir_startino = rrp->ir_startino;
-	}
-	/*
-	 * Find the left block number by looking in the buffer.
-	 * Adjust numrecs, sibling pointers.
-	 */
-	be16_add(&left->bb_numrecs, -(be16_to_cpu(right->bb_numrecs)));
-	right->bb_rightsib = left->bb_rightsib;
-	left->bb_rightsib = cpu_to_be32(args.agbno);
-	right->bb_leftsib = cpu_to_be32(lbno);
-	xfs_inobt_log_block(args.tp, rbp, XFS_BB_ALL_BITS);
-	xfs_inobt_log_block(args.tp, lbp, XFS_BB_NUMRECS | XFS_BB_RIGHTSIB);
-	/*
-	 * If there's a block to the new block's right, make that block
-	 * point back to right instead of to left.
-	 */
-	if (be32_to_cpu(right->bb_rightsib) != NULLAGBLOCK) {
-		xfs_inobt_block_t	*rrblock;	/* rr btree block */
-		xfs_buf_t		*rrbp;		/* buffer for rrblock */
-
-		if ((error = xfs_btree_read_bufs(args.mp, args.tp, args.agno,
-				be32_to_cpu(right->bb_rightsib), 0, &rrbp,
-				XFS_INO_BTREE_REF)))
-			return error;
-		rrblock = XFS_BUF_TO_INOBT_BLOCK(rrbp);
-		if ((error = xfs_btree_check_sblock(cur, rrblock, level, rrbp)))
-			return error;
-		rrblock->bb_leftsib = cpu_to_be32(args.agbno);
-		xfs_inobt_log_block(args.tp, rrbp, XFS_BB_LEFTSIB);
-	}
-	/*
-	 * If the cursor is really in the right block, move it there.
-	 * If it's just pointing past the last entry in left, then we'll
-	 * insert there, so don't change anything in that case.
-	 */
-	if (cur->bc_ptrs[level] > be16_to_cpu(left->bb_numrecs) + 1) {
-		xfs_btree_setbuf(cur, level, rbp);
-		cur->bc_ptrs[level] -= be16_to_cpu(left->bb_numrecs);
-	}
-	/*
-	 * If there are more levels, we'll need another cursor which refers
-	 * the right block, no matter where this cursor was.
-	 */
-	if (level + 1 < cur->bc_nlevels) {
-		if ((error = xfs_btree_dup_cursor(cur, curp)))
-			return error;
-		(*curp)->bc_ptrs[level + 1]++;
-	}
-	*bnop = args.agbno;
-	*stat = 1;
-	return 0;
-}
-
-/*
  * Externally visible routines.
  */
 
@@ -1243,6 +1085,48 @@ xfs_inobt_dup_cursor(
 }
 
 STATIC int
+xfs_inobt_alloc_block(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_ptr	*start,
+	union xfs_btree_ptr	*new,
+	int			length,
+	int			*stat)
+{
+	xfs_alloc_arg_t		args;		/* block allocation args */
+	int			error;		/* error return value */
+	xfs_agblock_t		sbno = be32_to_cpu(start->s);
+
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+
+	memset(&args, 0, sizeof(args));
+	args.tp = cur->bc_tp;
+	args.mp = cur->bc_mp;
+	args.fsbno = XFS_AGB_TO_FSB(args.mp, cur->bc_private.a.agno, sbno);
+	args.minlen = 1;
+	args.maxlen = 1;
+	args.prod = 1;
+	args.type = XFS_ALLOCTYPE_NEAR_BNO;
+
+	error = xfs_alloc_vextent(&args);
+	if (error) {
+		XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+		return error;
+	}
+	if (args.fsbno == NULLFSBLOCK) {
+		XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+		*stat = 0;
+		return 0;
+	}
+	ASSERT(args.len == 1);
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+
+	new->s = cpu_to_be32(XFS_FSB_TO_AGBNO(args.mp, args.fsbno));
+	*stat = 1;
+	return 0;
+}
+
+
+STATIC int
 xfs_inobt_get_maxrecs(
 	struct xfs_btree_cur	*cur,
 	int			level)
@@ -1517,6 +1401,7 @@ xfs_inobt_trace_record(
 
 static const struct xfs_btree_ops xfs_inobt_ops = {
 	.dup_cursor		= xfs_inobt_dup_cursor,
+	.alloc_block		= xfs_inobt_alloc_block,
 	.get_maxrecs		= xfs_inobt_get_maxrecs,
 	.init_key_from_rec	= xfs_inobt_init_key_from_rec,
 	.init_ptr_from_cur	= xfs_inobt_init_ptr_from_cur,
Index: linux-2.6-xfs/fs/xfs/xfs_bmap_btree.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_bmap_btree.c	2008-07-29 16:48:45.000000000 +0200
+++ linux-2.6-xfs/fs/xfs/xfs_bmap_btree.c	2008-07-29 16:48:46.000000000 +0200
@@ -52,8 +52,6 @@
 STATIC int xfs_bmbt_killroot(xfs_btree_cur_t *);
 STATIC void xfs_bmbt_log_keys(xfs_btree_cur_t *, xfs_buf_t *, int, int);
 STATIC void xfs_bmbt_log_ptrs(xfs_btree_cur_t *, xfs_buf_t *, int, int);
-STATIC int xfs_bmbt_split(xfs_btree_cur_t *, int, xfs_fsblock_t *,
-		__uint64_t *, xfs_btree_cur_t **, int *);
 
 #undef EXIT
 
@@ -549,13 +547,17 @@ xfs_bmbt_insrec(
 				if (i) {
 					optr = ptr = cur->bc_ptrs[level];
 				} else {
-					if ((error = xfs_bmbt_split(cur, level,
-							&nbno, &startoff, &ncur,
+					union xfs_btree_ptr bno = { .l = cpu_to_be64(nbno) };
+					union xfs_btree_key skey;
+					if ((error = xfs_btree_split(cur, level,
+							&bno, &skey, &ncur,
 							&i))) {
 						XFS_BMBT_TRACE_CURSOR(cur,
 							ERROR);
 						return error;
 					}
+					nbno = be64_to_cpu(bno.l);
+					startoff = be64_to_cpu(skey.bmbt.br_startoff);
 					if (i) {
 						block = xfs_bmbt_get_block(
 							    cur, level, &bp);
@@ -788,184 +790,6 @@ xfs_extent_state(
 	return XFS_EXT_NORM;
 }
 
-
-/*
- * Split cur/level block in half.
- * Return new block number and its first record (to be inserted into parent).
- */
-STATIC int					/* error */
-xfs_bmbt_split(
-	xfs_btree_cur_t		*cur,
-	int			level,
-	xfs_fsblock_t		*bnop,
-	__uint64_t		*startoff,
-	xfs_btree_cur_t		**curp,
-	int			*stat)		/* success/failure */
-{
-	xfs_alloc_arg_t		args;		/* block allocation args */
-	int			error;		/* error return value */
-	int			i;		/* loop counter */
-	xfs_fsblock_t		lbno;		/* left sibling block number */
-	xfs_buf_t		*lbp;		/* left buffer pointer */
-	xfs_bmbt_block_t	*left;		/* left btree block */
-	xfs_bmbt_key_t		*lkp;		/* left btree key */
-	xfs_bmbt_ptr_t		*lpp;		/* left address pointer */
-	xfs_bmbt_rec_t		*lrp;		/* left record pointer */
-	xfs_buf_t		*rbp;		/* right buffer pointer */
-	xfs_bmbt_block_t	*right;		/* right btree block */
-	xfs_bmbt_key_t		*rkp;		/* right btree key */
-	xfs_bmbt_ptr_t		*rpp;		/* right address pointer */
-	xfs_bmbt_block_t	*rrblock;	/* right-right btree block */
-	xfs_buf_t		*rrbp;		/* right-right buffer pointer */
-	xfs_bmbt_rec_t		*rrp;		/* right record pointer */
-
-	XFS_BMBT_TRACE_CURSOR(cur, ENTRY);
-	// disable until merged into common code
-//	XFS_BMBT_TRACE_ARGIFK(cur, level, *bnop, *startoff);
-	args.tp = cur->bc_tp;
-	args.mp = cur->bc_mp;
-	lbp = cur->bc_bufs[level];
-	lbno = XFS_DADDR_TO_FSB(args.mp, XFS_BUF_ADDR(lbp));
-	left = XFS_BUF_TO_BMBT_BLOCK(lbp);
-	args.fsbno = cur->bc_private.b.firstblock;
-	args.firstblock = args.fsbno;
-	args.minleft = 0;
-	if (args.fsbno == NULLFSBLOCK) {
-		args.fsbno = lbno;
-		args.type = XFS_ALLOCTYPE_START_BNO;
-		/*
-		 * Make sure there is sufficient room left in the AG to
-		 * complete a full tree split for an extent insert.  If
-		 * we are converting the middle part of an extent then
-		 * we may need space for two tree splits.
-		 *
-		 * We are relying on the caller to make the correct block
-		 * reservation for this operation to succeed.  If the
-		 * reservation amount is insufficient then we may fail a
-		 * block allocation here and corrupt the filesystem.
-		 */
-		args.minleft = xfs_trans_get_block_res(args.tp);
-	} else if (cur->bc_private.b.flist->xbf_low)
-		args.type = XFS_ALLOCTYPE_START_BNO;
-	else
-		args.type = XFS_ALLOCTYPE_NEAR_BNO;
-	args.mod = args.alignment = args.total = args.isfl =
-		args.userdata = args.minalignslop = 0;
-	args.minlen = args.maxlen = args.prod = 1;
-	args.wasdel = cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL;
-	if (!args.wasdel && xfs_trans_get_block_res(args.tp) == 0) {
-		XFS_BMBT_TRACE_CURSOR(cur, ERROR);
-		return XFS_ERROR(ENOSPC);
-	}
-	if ((error = xfs_alloc_vextent(&args))) {
-		XFS_BMBT_TRACE_CURSOR(cur, ERROR);
-		return error;
-	}
-	if (args.fsbno == NULLFSBLOCK && args.minleft) {
-		/*
-		 * Could not find an AG with enough free space to satisfy
-		 * a full btree split.  Try again without minleft and if
-		 * successful activate the lowspace algorithm.
-		 */
-		args.fsbno = 0;
-		args.type = XFS_ALLOCTYPE_FIRST_AG;
-		args.minleft = 0;
-		if ((error = xfs_alloc_vextent(&args))) {
-			XFS_BMBT_TRACE_CURSOR(cur, ERROR);
-			return error;
-		}
-		cur->bc_private.b.flist->xbf_low = 1;
-	}
-	if (args.fsbno == NULLFSBLOCK) {
-		XFS_BMBT_TRACE_CURSOR(cur, EXIT);
-		*stat = 0;
-		return 0;
-	}
-	ASSERT(args.len == 1);
-	cur->bc_private.b.firstblock = args.fsbno;
-	cur->bc_private.b.allocated++;
-	cur->bc_private.b.ip->i_d.di_nblocks++;
-	xfs_trans_log_inode(args.tp, cur->bc_private.b.ip, XFS_ILOG_CORE);
-	XFS_TRANS_MOD_DQUOT_BYINO(args.mp, args.tp, cur->bc_private.b.ip,
-			XFS_TRANS_DQ_BCOUNT, 1L);
-	rbp = xfs_btree_get_bufl(args.mp, args.tp, args.fsbno, 0);
-	right = XFS_BUF_TO_BMBT_BLOCK(rbp);
-#ifdef DEBUG
-	if ((error = xfs_btree_check_lblock(cur, left, level, rbp))) {
-		XFS_BMBT_TRACE_CURSOR(cur, ERROR);
-		return error;
-	}
-#endif
-	right->bb_magic = cpu_to_be32(XFS_BMAP_MAGIC);
-	right->bb_level = left->bb_level;
-	right->bb_numrecs = cpu_to_be16(be16_to_cpu(left->bb_numrecs) / 2);
-	if ((be16_to_cpu(left->bb_numrecs) & 1) &&
-	    cur->bc_ptrs[level] <= be16_to_cpu(right->bb_numrecs) + 1)
-		be16_add(&right->bb_numrecs, 1);
-	i = be16_to_cpu(left->bb_numrecs) - be16_to_cpu(right->bb_numrecs) + 1;
-	if (level > 0) {
-		lkp = XFS_BMAP_KEY_IADDR(left, i, cur);
-		lpp = XFS_BMAP_PTR_IADDR(left, i, cur);
-		rkp = XFS_BMAP_KEY_IADDR(right, 1, cur);
-		rpp = XFS_BMAP_PTR_IADDR(right, 1, cur);
-#ifdef DEBUG
-		for (i = 0; i < be16_to_cpu(right->bb_numrecs); i++) {
-			if ((error = xfs_btree_check_lptr_disk(cur, lpp[i], level))) {
-				XFS_BMBT_TRACE_CURSOR(cur, ERROR);
-				return error;
-			}
-		}
-#endif
-		memcpy(rkp, lkp, be16_to_cpu(right->bb_numrecs) * sizeof(*rkp));
-		memcpy(rpp, lpp, be16_to_cpu(right->bb_numrecs) * sizeof(*rpp));
-		xfs_bmbt_log_keys(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-		xfs_bmbt_log_ptrs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-		*startoff = be64_to_cpu(rkp->br_startoff);
-	} else {
-		lrp = XFS_BMAP_REC_IADDR(left, i, cur);
-		rrp = XFS_BMAP_REC_IADDR(right, 1, cur);
-		memcpy(rrp, lrp, be16_to_cpu(right->bb_numrecs) * sizeof(*rrp));
-		xfs_bmbt_log_recs(cur, rbp, 1, be16_to_cpu(right->bb_numrecs));
-		*startoff = xfs_bmbt_disk_get_startoff(rrp);
-	}
-	be16_add(&left->bb_numrecs, -(be16_to_cpu(right->bb_numrecs)));
-	right->bb_rightsib = left->bb_rightsib;
-	left->bb_rightsib = cpu_to_be64(args.fsbno);
-	right->bb_leftsib = cpu_to_be64(lbno);
-	xfs_bmbt_log_block(cur, rbp, XFS_BB_ALL_BITS);
-	xfs_bmbt_log_block(cur, lbp, XFS_BB_NUMRECS | XFS_BB_RIGHTSIB);
-	if (be64_to_cpu(right->bb_rightsib) != NULLDFSBNO) {
-		if ((error = xfs_btree_read_bufl(args.mp, args.tp,
-				be64_to_cpu(right->bb_rightsib), 0, &rrbp,
-				XFS_BMAP_BTREE_REF))) {
-			XFS_BMBT_TRACE_CURSOR(cur, ERROR);
-			return error;
-		}
-		rrblock = XFS_BUF_TO_BMBT_BLOCK(rrbp);
-		if ((error = xfs_btree_check_lblock(cur, rrblock, level, rrbp))) {
-			XFS_BMBT_TRACE_CURSOR(cur, ERROR);
-			return error;
-		}
-		rrblock->bb_leftsib = cpu_to_be64(args.fsbno);
-		xfs_bmbt_log_block(cur, rrbp, XFS_BB_LEFTSIB);
-	}
-	if (cur->bc_ptrs[level] > be16_to_cpu(left->bb_numrecs) + 1) {
-		xfs_btree_setbuf(cur, level, rbp);
-		cur->bc_ptrs[level] -= be16_to_cpu(left->bb_numrecs);
-	}
-	if (level + 1 < cur->bc_nlevels) {
-		if ((error = xfs_btree_dup_cursor(cur, curp))) {
-			XFS_BMBT_TRACE_CURSOR(cur, ERROR);
-			return error;
-		}
-		(*curp)->bc_ptrs[level + 1]++;
-	}
-	*bnop = args.fsbno;
-	XFS_BMBT_TRACE_CURSOR(cur, EXIT);
-	*stat = 1;
-	return 0;
-}
-
 /*
  * Convert on-disk form of btree root to in-memory form.
  */
@@ -1672,6 +1496,92 @@ xfs_bmbt_dup_cursor(
 	return new;
 }
 
+STATIC int
+xfs_bmbt_alloc_block(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_ptr	*start,
+	union xfs_btree_ptr	*new,
+	int			length,
+	int			*stat)
+{
+	xfs_alloc_arg_t		args;		/* block allocation args */
+	int			error;		/* error return value */
+
+	memset(&args, 0, sizeof(args));
+	args.tp = cur->bc_tp;
+	args.mp = cur->bc_mp;
+	args.fsbno = cur->bc_private.b.firstblock;
+	args.firstblock = args.fsbno;
+
+	if (args.fsbno == NULLFSBLOCK) {
+		args.fsbno = be64_to_cpu(start->l);
+		args.type = XFS_ALLOCTYPE_START_BNO;
+		/*
+		 * Make sure there is sufficient room left in the AG to
+		 * complete a full tree split for an extent insert.  If
+		 * we are converting the middle part of an extent then
+		 * we may need space for two tree splits.
+		 *
+		 * We are relying on the caller to make the correct block
+		 * reservation for this operation to succeed.  If the
+		 * reservation amount is insufficient then we may fail a
+		 * block allocation here and corrupt the filesystem.
+		 */
+		args.minleft = xfs_trans_get_block_res(args.tp);
+	} else if (cur->bc_private.b.flist->xbf_low) {
+		args.type = XFS_ALLOCTYPE_START_BNO;
+	} else {
+		args.type = XFS_ALLOCTYPE_NEAR_BNO;
+	}
+
+	args.minlen = args.maxlen = args.prod = 1;
+	args.wasdel = cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL;
+	if (!args.wasdel && xfs_trans_get_block_res(args.tp) == 0) {
+		error = XFS_ERROR(ENOSPC);
+		goto error0;
+	}
+	error = xfs_alloc_vextent(&args);
+	if (error)
+		goto error0;
+
+	if (args.fsbno == NULLFSBLOCK && args.minleft) {
+		/*
+		 * Could not find an AG with enough free space to satisfy
+		 * a full btree split.  Try again without minleft and if
+		 * successful activate the lowspace algorithm.
+		 */
+		args.fsbno = 0;
+		args.type = XFS_ALLOCTYPE_FIRST_AG;
+		args.minleft = 0;
+		error = xfs_alloc_vextent(&args);
+		if (error)
+			goto error0;
+		cur->bc_private.b.flist->xbf_low = 1;
+	}
+	if (args.fsbno == NULLFSBLOCK) {
+		XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+		*stat = 0;
+		return 0;
+	}
+	ASSERT(args.len == 1);
+	cur->bc_private.b.firstblock = args.fsbno;
+	cur->bc_private.b.allocated++;
+	cur->bc_private.b.ip->i_d.di_nblocks++;
+	xfs_trans_log_inode(args.tp, cur->bc_private.b.ip, XFS_ILOG_CORE);
+	XFS_TRANS_MOD_DQUOT_BYINO(args.mp, args.tp, cur->bc_private.b.ip,
+			XFS_TRANS_DQ_BCOUNT, 1L);
+
+	new->l = cpu_to_be64(args.fsbno);
+
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+	*stat = 1;
+	return 0;
+
+ error0:
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+	return error;
+}
+
 STATIC struct xfs_btree_block *
 xfs_bmbt_get_root_from_inode(
 	struct xfs_btree_cur	*cur)
@@ -1975,6 +1885,7 @@ xfs_bmbt_trace_record(
 static const struct xfs_btree_ops xfs_bmbt_ops = {
 	.dup_cursor		= xfs_bmbt_dup_cursor,
 	.get_root_from_inode	= xfs_bmbt_get_root_from_inode,
+	.alloc_block		= xfs_bmbt_alloc_block,
 	.init_key_from_rec	= xfs_bmbt_init_key_from_rec,
 	.init_ptr_from_cur	= xfs_bmbt_init_ptr_from_cur,
 	.get_maxrecs		= xfs_bmbt_get_maxrecs,

-- 

Re: [PATCH 17/21] implement generic xfs_btree_split

[Dave Chinner]

On Tue, Jul 29, 2008 at 09:31:37PM +0200, Christoph Hellwig wrote:
> Make the btree split code generic.  Based on a patch from David Chinner
> with lots of changes to follow the original btree implementations more
> closely.  While this loses some of the generic helper routines for
> inserting/moving/removing records it also solves some of the one off
> bugs in the original code and makes it easier to verify.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
.....
> +STATIC void
> +xfs_btree_init_block(
> +	struct xfs_btree_cur	*cur,
> +	int			level,
> +	int			numrecs,
> +	struct xfs_btree_block	*new)	/* new block */
> +{
> +	new->bb_h.bb_magic = cpu_to_be32(xfs_magics[cur->bc_btnum]);
> +	new->bb_h.bb_level = cpu_to_be16(level);
> +	new->bb_h.bb_numrecs = cpu_to_be16(numrecs);
> +
> +	if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
> +		new->bb_u.l.bb_leftsib = cpu_to_be64(NULLFSBLOCK);
> +		new->bb_u.l.bb_rightsib = cpu_to_be64(NULLFSBLOCK);
> +	} else {
> +		new->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
> +		new->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
> +	}
> +}

This is where I begin to question this approach (i.e. using
helpers like this rather than specific ops like I did). It's
taken me 4 ŏr 5 patches to put my finger on it.

The intent of this factorisation is to make implementing new btree
structures easy, not making the current code better or more
managable. The first thing we need is is btrees with different
header blocks (self describing information, CRCs, etc). This above
function will suddenly have four combinations to deal with - long and
short, version 1 and version 2 header formats. The more we change,
the more this complicates these helpers. That is why I pushed
seemingly trivial stuff out to operations vectors - because of the
future flexibility it allowed in implementation of new btrees.....

I don't see this a problem for this patch series, but I can see that
some of this work will end up being converted back to ops vectors
as soon as we start modifying between structures....


> +STATIC int
> +xfs_btree_get_buf_block(
> +	struct xfs_btree_cur	*cur,
> +	union xfs_btree_ptr	*ptr,
> +	int			flags,
> +	struct xfs_btree_block	**block,
> +	struct xfs_buf		**bpp)
> +{
> +	struct xfs_mount	*mp = cur->bc_mp;
> +	xfs_daddr_t		d;
> +
> +	/* need to sort out how callers deal with failures first */
> +	ASSERT(!(flags & XFS_BUF_TRYLOCK));
> +
> +	d = xfs_btree_ptr_to_daddr(cur, ptr);
> +	*bpp = xfs_trans_get_buf(cur->bc_tp, mp->m_ddev_targp, d,
> +				 mp->m_bsize, flags);
> +
> +	ASSERT(*bpp);
> +	ASSERT(!XFS_BUF_GETERROR(*bpp));

xfs_trans_get_buf() can return NULL, right?

> +	/* block allocation / freeing */
> +	int	(*alloc_block)(struct xfs_btree_cur *cur,
> +			       union xfs_btree_ptr *sbno,
> +			       union xfs_btree_ptr *nbno,

start_bno, new_bno.

Otherwise looks good.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

Re: [PATCH 17/21] implement generic xfs_btree_split

[Christoph Hellwig]

> This is where I begin to question this approach (i.e. using
> helpers like this rather than specific ops like I did). It's
> taken me 4 ??r 5 patches to put my finger on it.
> 
> The intent of this factorisation is to make implementing new btree
> structures easy, not making the current code better or more
> managable. The first thing we need is is btrees with different
> header blocks (self describing information, CRCs, etc). This above
> function will suddenly have four combinations to deal with - long and
> short, version 1 and version 2 header formats. The more we change,
> the more this complicates these helpers. That is why I pushed
> seemingly trivial stuff out to operations vectors - because of the
> future flexibility it allowed in implementation of new btrees.....
> 
> I don't see this a problem for this patch series, but I can see that
> some of this work will end up being converted back to ops vectors
> as soon as we start modifying between structures....

Maybe.  But even when we convert it to ops vectors it should not
be the btree implementation vector, but a btree_block_ops that's
implemented once instead of duplicated for the alloc vs ialloc
btree.  And for now having all this in xfs_btree.c makes reading
and working on the patch series easier, so..

> > +	/* need to sort out how callers deal with failures first */
> > +	ASSERT(!(flags & XFS_BUF_TRYLOCK));
> > +
> > +	d = xfs_btree_ptr_to_daddr(cur, ptr);
> > +	*bpp = xfs_trans_get_buf(cur->bc_tp, mp->m_ddev_targp, d,
> > +				 mp->m_bsize, flags);
> > +
> > +	ASSERT(*bpp);
> > +	ASSERT(!XFS_BUF_GETERROR(*bpp));
> 
> xfs_trans_get_buf() can return NULL, right?

Only when XFS_BUF_TRYLOCK is set, which it never is for the
btree code, and the assert above makes sure we catch any new caller
early.

> > +	/* block allocation / freeing */
> > +	int	(*alloc_block)(struct xfs_btree_cur *cur,
> > +			       union xfs_btree_ptr *sbno,
> > +			       union xfs_btree_ptr *nbno,
> 
> start_bno, new_bno.

Done.

Re: [PATCH 17/21] implement generic xfs_btree_split

[Dave Chinner]

On Fri, Aug 01, 2008 at 09:55:07PM +0200, Christoph Hellwig wrote:
> > This is where I begin to question this approach (i.e. using
> > helpers like this rather than specific ops like I did). It's
> > taken me 4 ??r 5 patches to put my finger on it.
> > 
> > The intent of this factorisation is to make implementing new btree
> > structures easy, not making the current code better or more
> > managable. The first thing we need is is btrees with different
> > header blocks (self describing information, CRCs, etc). This above
> > function will suddenly have four combinations to deal with - long and
> > short, version 1 and version 2 header formats. The more we change,
> > the more this complicates these helpers. That is why I pushed
> > seemingly trivial stuff out to operations vectors - because of the
> > future flexibility it allowed in implementation of new btrees.....
> > 
> > I don't see this a problem for this patch series, but I can see that
> > some of this work will end up being converted back to ops vectors
> > as soon as we start modifying between structures....
> 
> Maybe.  But even when we convert it to ops vectors it should not
> be the btree implementation vector, but a btree_block_ops that's
> implemented once instead of duplicated for the alloc vs ialloc
> btree.

Yes, that makes sense - I had sort of headed that way, but it
was not fully though out...

> And for now having all this in xfs_btree.c makes reading
> and working on the patch series easier, so..

Fair enough - do the work when we implement a new btree ;)

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com