Re: [PATCH 07/47] xfs: add function pointers for get/update keys to the btree

[Christoph Hellwig <hch@infradead.org>]

On Mon, Aug 01, 2016 at 10:33:31AM -0700, Darrick J. Wong wrote:
> That's roughly the approach I took in previous versions of this patch,
> but using the OVERLAPPING flag to dispatch the overlapped vs. non-
> versions of the get*keys and updkey* functions confused Dave, so he
> asked me to add to function pointers[1] to the btree ops and dispatch
> that way.

I remember I had a similar disagreement with Dave on the long vs
short pointers when doing the initial common btree work, and
I prevailed using the flag :)

Below is a patch to on top of your for-dave-for-4.8-2 branch
which uses the flag, but also keeps your useful refactoring.

This both reduces source:

 6 files changed, 61 insertions(+), 136 deletions(-)

as well as binary:

hch@brick:~/work/xfs$ size xfs.o-*
   text	   data	    bss	    dec	    hex	filename
 911881	 160951	   1568	1074400	 1064e0	xfs.o-flag
 912457	 160951	   1568	1074976	 106720	xfs.o-pointer

sizes and makes the whole thing much easier to follow and understand.


diff --git a/fs/xfs/libxfs/xfs_alloc_btree.c b/fs/xfs/libxfs/xfs_alloc_btree.c
index c60eeb8..5ba2dac 100644
--- a/fs/xfs/libxfs/xfs_alloc_btree.c
+++ b/fs/xfs/libxfs/xfs_alloc_btree.c
@@ -403,10 +403,6 @@ static const struct xfs_btree_ops xfs_allocbt_ops = {
 	.keys_inorder		= xfs_allocbt_keys_inorder,
 	.recs_inorder		= xfs_allocbt_recs_inorder,
 #endif
-
-	.get_leaf_keys		= xfs_btree_get_leaf_keys,
-	.get_node_keys		= xfs_btree_get_node_keys,
-	.update_keys		= xfs_btree_update_keys,
 };
 
 /*
diff --git a/fs/xfs/libxfs/xfs_bmap_btree.c b/fs/xfs/libxfs/xfs_bmap_btree.c
index 9e34ca4..cd85274 100644
--- a/fs/xfs/libxfs/xfs_bmap_btree.c
+++ b/fs/xfs/libxfs/xfs_bmap_btree.c
@@ -763,10 +763,6 @@ static const struct xfs_btree_ops xfs_bmbt_ops = {
 	.keys_inorder		= xfs_bmbt_keys_inorder,
 	.recs_inorder		= xfs_bmbt_recs_inorder,
 #endif
-
-	.get_leaf_keys		= xfs_btree_get_leaf_keys,
-	.get_node_keys		= xfs_btree_get_node_keys,
-	.update_keys		= xfs_btree_update_keys,
 };
 
 /*
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index fe5f27e..45a9545b 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -1951,29 +1951,6 @@ error0:
 	return error;
 }
 
-/* Determine the low key of a leaf block (simple) */
-void
-xfs_btree_get_leaf_keys(
-	struct xfs_btree_cur	*cur,
-	struct xfs_btree_block	*block,
-	union xfs_btree_key	*key)
-{
-	union xfs_btree_rec	*rec;
-
-	rec = xfs_btree_rec_addr(cur, 1, block);
-	cur->bc_ops->init_key_from_rec(key, rec);
-}
-
-/* Determine the low key of a node block (simple) */
-void
-xfs_btree_get_node_keys(
-	struct xfs_btree_cur	*cur,
-	struct xfs_btree_block	*block,
-	union xfs_btree_key	*key)
-{
-	memcpy(key, xfs_btree_key_addr(cur, 1, block), cur->bc_ops->key_len);
-}
-
 /* Find the high key storage area from a regular key. */
 STATIC union xfs_btree_key *
 xfs_btree_high_key_from_key(
@@ -1985,38 +1962,41 @@ xfs_btree_high_key_from_key(
 			(cur->bc_ops->key_len / 2));
 }
 
-/* Determine the low and high keys of a leaf block (overlapped) */
-void
-xfs_btree_get_leaf_keys_overlapped(
+/* Determine the low (and high if overlapped) key of a leaf block */
+STATIC void
+xfs_btree_get_leaf_keys(
 	struct xfs_btree_cur	*cur,
 	struct xfs_btree_block	*block,
 	union xfs_btree_key	*key)
 {
-	int			n;
 	union xfs_btree_rec	*rec;
-	union xfs_btree_key	max_hkey;
-	union xfs_btree_key	hkey;
-	union xfs_btree_key	*high;
 
-	ASSERT(cur->bc_flags & XFS_BTREE_OVERLAPPING);
 	rec = xfs_btree_rec_addr(cur, 1, block);
 	cur->bc_ops->init_key_from_rec(key, rec);
 
-	cur->bc_ops->init_high_key_from_rec(&max_hkey, rec);
-	for (n = 2; n <= xfs_btree_get_numrecs(block); n++) {
-		rec = xfs_btree_rec_addr(cur, n, block);
-		cur->bc_ops->init_high_key_from_rec(&hkey, rec);
-		if (cur->bc_ops->diff_two_keys(cur, &hkey, &max_hkey) > 0)
-			max_hkey = hkey;
-	}
+	if (cur->bc_flags & XFS_BTREE_OVERLAPPING) {
+		union xfs_btree_key	max_hkey;
+		union xfs_btree_key	hkey;
+		union xfs_btree_key	*high;
+		int			n;
+
+		cur->bc_ops->init_high_key_from_rec(&max_hkey, rec);
+		for (n = 2; n <= xfs_btree_get_numrecs(block); n++) {
+			rec = xfs_btree_rec_addr(cur, n, block);
+			cur->bc_ops->init_high_key_from_rec(&hkey, rec);
+			if (cur->bc_ops->diff_two_keys(cur, &hkey, &max_hkey)
+					> 0)
+				max_hkey = hkey;
+		}
 
-	high = xfs_btree_high_key_from_key(cur, key);
-	memcpy(high, &max_hkey, cur->bc_ops->key_len / 2);
+		high = xfs_btree_high_key_from_key(cur, key);
+		memcpy(high, &max_hkey, cur->bc_ops->key_len / 2);
+	}
 }
 
 /* Determine the low and high keys of a node block (overlapped) */
-void
-xfs_btree_get_node_keys_overlapped(
+STATIC void
+xfs_btree_get_node_keys(
 	struct xfs_btree_cur	*cur,
 	struct xfs_btree_block	*block,
 	union xfs_btree_key	*key)
@@ -2026,19 +2006,23 @@ xfs_btree_get_node_keys_overlapped(
 	union xfs_btree_key	*max_hkey;
 	union xfs_btree_key	*high;
 
-	ASSERT(cur->bc_flags & XFS_BTREE_OVERLAPPING);
-	memcpy(key, xfs_btree_key_addr(cur, 1, block),
-			cur->bc_ops->key_len / 2);
-
-	max_hkey = xfs_btree_high_key_addr(cur, 1, block);
-	for (n = 2; n <= xfs_btree_get_numrecs(block); n++) {
-		hkey = xfs_btree_high_key_addr(cur, n, block);
-		if (cur->bc_ops->diff_two_keys(cur, hkey, max_hkey) > 0)
-			max_hkey = hkey;
-	}
+	if (cur->bc_flags & XFS_BTREE_OVERLAPPING) {
+		memcpy(key, xfs_btree_key_addr(cur, 1, block),
+				cur->bc_ops->key_len / 2);
+
+		max_hkey = xfs_btree_high_key_addr(cur, 1, block);
+		for (n = 2; n <= xfs_btree_get_numrecs(block); n++) {
+			hkey = xfs_btree_high_key_addr(cur, n, block);
+			if (cur->bc_ops->diff_two_keys(cur, hkey, max_hkey) > 0)
+				max_hkey = hkey;
+		}
 
-	high = xfs_btree_high_key_from_key(cur, key);
-	memcpy(high, max_hkey, cur->bc_ops->key_len / 2);
+		high = xfs_btree_high_key_from_key(cur, key);
+		memcpy(high, max_hkey, cur->bc_ops->key_len / 2);
+	} else {
+		memcpy(key, xfs_btree_key_addr(cur, 1, block),
+				cur->bc_ops->key_len);
+	}
 }
 
 /* Derive the keys for any btree block. */
@@ -2049,9 +2033,9 @@ xfs_btree_get_keys(
 	union xfs_btree_key	*key)
 {
 	if (be16_to_cpu(block->bb_level) == 0)
-		cur->bc_ops->get_leaf_keys(cur, block, key);
+		xfs_btree_get_leaf_keys(cur, block, key);
 	else
-		cur->bc_ops->get_node_keys(cur, block, key);
+		xfs_btree_get_node_keys(cur, block, key);
 }
 
 /*
@@ -2125,28 +2109,12 @@ __xfs_btree_updkeys(
 		xfs_btree_log_keys(cur, bp, ptr, ptr);
 		if (level + 1 >= cur->bc_nlevels)
 			break;
-		cur->bc_ops->get_node_keys(cur, block, lkey);
+		xfs_btree_get_node_keys(cur, block, lkey);
 	}
 
 	return 0;
 }
 
-/*
- * Update all the keys from some level in cursor back to the root, stopping
- * when we find a key pair that don't need updating.
- */
-int
-xfs_btree_update_keys_overlapped(
-	struct xfs_btree_cur	*cur,
-	int			level)
-{
-	struct xfs_buf		*bp;
-	struct xfs_btree_block	*block;
-
-	block = xfs_btree_get_block(cur, level, &bp);
-	return __xfs_btree_updkeys(cur, level, block, bp, false);
-}
-
 /* Update all the keys from some level in cursor back to the root. */
 STATIC int
 xfs_btree_updkeys_force(
@@ -2163,7 +2131,7 @@ xfs_btree_updkeys_force(
 /*
  * Update the parent keys of the given level, progressing towards the root.
  */
-int
+STATIC int
 xfs_btree_update_keys(
 	struct xfs_btree_cur	*cur,
 	int			level)
@@ -2174,20 +2142,21 @@ xfs_btree_update_keys(
 	union xfs_btree_key	key;
 	int			ptr;
 
-	ASSERT(!(cur->bc_flags & XFS_BTREE_OVERLAPPING));
+	ASSERT(level >= 0);
+
+	block = xfs_btree_get_block(cur, level, &bp);
+	if (cur->bc_flags & XFS_BTREE_OVERLAPPING)
+		return __xfs_btree_updkeys(cur, level, block, bp, false);
 
 	XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
 	XFS_BTREE_TRACE_ARGIK(cur, level, keyp);
 
-	ASSERT(level >= 0);
-
 	/*
 	 * Go up the tree from this level toward the root.
 	 * At each level, update the key value to the value input.
 	 * Stop when we reach a level where the cursor isn't pointing
 	 * at the first entry in the block.
 	 */
-	block = xfs_btree_get_block(cur, level, &bp);
 	xfs_btree_get_keys(cur, block, &key);
 	for (level++, ptr = 1; ptr == 1 && level < cur->bc_nlevels; level++) {
 #ifdef DEBUG
@@ -2257,7 +2226,7 @@ xfs_btree_update(
 
 	/* Pass new key value up to our parent. */
 	if (xfs_btree_needs_key_update(cur, ptr)) {
-		error = cur->bc_ops->update_keys(cur, 0);
+		error = xfs_btree_update_keys(cur, 0);
 		if (error)
 			goto error0;
 	}
@@ -2447,13 +2416,13 @@ xfs_btree_lshift(
 		goto error1;
 
 	/* Update the parent keys of the right block. */
-	error = cur->bc_ops->update_keys(cur, level);
+	error = xfs_btree_update_keys(cur, level);
 	if (error)
 		goto error1;
 
 	/* Update the parent high keys of the left block, if needed. */
 	if (tcur->bc_flags & XFS_BTREE_OVERLAPPING) {
-		error = tcur->bc_ops->update_keys(tcur, level);
+		error = xfs_btree_update_keys(tcur, level);
 		if (error)
 			goto error1;
 	}
@@ -2633,13 +2602,13 @@ xfs_btree_rshift(
 
 	/* Update the parent high keys of the left block, if needed. */
 	if (cur->bc_flags & XFS_BTREE_OVERLAPPING) {
-		error = cur->bc_ops->update_keys(cur, level);
+		error = xfs_btree_update_keys(cur, level);
 		if (error)
 			goto error1;
 	}
 
 	/* Update the parent keys of the right block. */
-	error = cur->bc_ops->update_keys(tcur, level);
+	error = xfs_btree_update_keys(tcur, level);
 	if (error)
 		goto error1;
 
@@ -2778,7 +2747,7 @@ __xfs_btree_split(
 		xfs_btree_log_ptrs(cur, rbp, 1, rrecs);
 
 		/* Stash the keys of the new block for later insertion. */
-		cur->bc_ops->get_node_keys(cur, right, key);
+		xfs_btree_get_node_keys(cur, right, key);
 	} else {
 		/* It's a leaf.  Move records.  */
 		union xfs_btree_rec	*lrp;	/* left record pointer */
@@ -2792,7 +2761,7 @@ __xfs_btree_split(
 		xfs_btree_log_recs(cur, rbp, 1, rrecs);
 
 		/* Stash the keys of the new block for later insertion. */
-		cur->bc_ops->get_leaf_keys(cur, right, key);
+		xfs_btree_get_leaf_keys(cur, right, key);
 	}
 
 	/*
@@ -2822,7 +2791,7 @@ __xfs_btree_split(
 
 	/* Update the parent high keys of the left block, if needed. */
 	if (cur->bc_flags & XFS_BTREE_OVERLAPPING) {
-		error = cur->bc_ops->update_keys(cur, level);
+		error = xfs_btree_update_keys(cur, level);
 		if (error)
 			goto error0;
 	}
@@ -3143,9 +3112,9 @@ xfs_btree_new_root(
 		 * Get the keys for the left block's keys and put them directly
 		 * in the parent block.  Do the same for the right block.
 		 */
-		cur->bc_ops->get_node_keys(cur, left,
+		xfs_btree_get_node_keys(cur, left,
 				xfs_btree_key_addr(cur, 1, new));
-		cur->bc_ops->get_node_keys(cur, right,
+		xfs_btree_get_node_keys(cur, right,
 				xfs_btree_key_addr(cur, 2, new));
 	} else {
 		/*
@@ -3153,9 +3122,9 @@ xfs_btree_new_root(
 		 * directly in the parent block.  Do the same for the right
 		 * block.
 		 */
-		cur->bc_ops->get_leaf_keys(cur, left,
+		xfs_btree_get_leaf_keys(cur, left,
 			xfs_btree_key_addr(cur, 1, new));
-		cur->bc_ops->get_leaf_keys(cur, right,
+		xfs_btree_get_leaf_keys(cur, right,
 			xfs_btree_key_addr(cur, 2, new));
 	}
 	xfs_btree_log_keys(cur, nbp, 1, 2);
@@ -3434,7 +3403,7 @@ xfs_btree_insrec(
 	if (bp && bp->b_bn != old_bn) {
 		xfs_btree_get_keys(cur, block, lkey);
 	} else if (xfs_btree_needs_key_update(cur, optr)) {
-		error = cur->bc_ops->update_keys(cur, level);
+		error = xfs_btree_update_keys(cur, level);
 		if (error)
 			goto error0;
 	}
@@ -3880,7 +3849,7 @@ xfs_btree_delrec(
 	 * key values above us in the tree.
 	 */
 	if (xfs_btree_needs_key_update(cur, ptr)) {
-		error = cur->bc_ops->update_keys(cur, level);
+		error = xfs_btree_update_keys(cur, level);
 		if (error)
 			goto error0;
 	}
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index 9b6d628..04d0865 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -214,19 +214,6 @@ struct xfs_btree_ops {
 				union xfs_btree_rec *r1,
 				union xfs_btree_rec *r2);
 #endif
-
-	/* derive the low & high keys from the records in a leaf block */
-	void	(*get_leaf_keys)(struct xfs_btree_cur *cur,
-				 struct xfs_btree_block *block,
-				 union xfs_btree_key *key);
-
-	/* derive the low & high keys from the keys in a node block */
-	void	(*get_node_keys)(struct xfs_btree_cur *cur,
-				 struct xfs_btree_block *block,
-				 union xfs_btree_key *key);
-
-	/* update the parent keys of given btree level */
-	int	(*update_keys)(struct xfs_btree_cur *cur, int level);
 };
 
 /*
@@ -527,17 +514,6 @@ bool xfs_btree_sblock_verify(struct xfs_buf *bp, unsigned int max_recs);
 uint xfs_btree_compute_maxlevels(struct xfs_mount *mp, uint *limits,
 				 unsigned long len);
 
-void xfs_btree_get_leaf_keys(struct xfs_btree_cur *cur,
-		struct xfs_btree_block *block, union xfs_btree_key *key);
-void xfs_btree_get_node_keys(struct xfs_btree_cur *cur,
-		struct xfs_btree_block *block, union xfs_btree_key *key);
-int xfs_btree_update_keys(struct xfs_btree_cur *cur, int level);
-void xfs_btree_get_leaf_keys_overlapped(struct xfs_btree_cur *cur,
-		struct xfs_btree_block *block, union xfs_btree_key *key);
-void xfs_btree_get_node_keys_overlapped(struct xfs_btree_cur *cur,
-		struct xfs_btree_block *block, union xfs_btree_key *key);
-int xfs_btree_update_keys_overlapped(struct xfs_btree_cur *cur, int level);
-
 /* return codes */
 #define XFS_BTREE_QUERY_RANGE_CONTINUE	0	/* keep iterating */
 #define XFS_BTREE_QUERY_RANGE_ABORT	1	/* stop iterating */
diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
index c83691e..31ca220 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.c
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
@@ -320,10 +320,6 @@ static const struct xfs_btree_ops xfs_inobt_ops = {
 	.keys_inorder		= xfs_inobt_keys_inorder,
 	.recs_inorder		= xfs_inobt_recs_inorder,
 #endif
-
-	.get_leaf_keys		= xfs_btree_get_leaf_keys,
-	.get_node_keys		= xfs_btree_get_node_keys,
-	.update_keys		= xfs_btree_update_keys,
 };
 
 static const struct xfs_btree_ops xfs_finobt_ops = {
@@ -345,10 +341,6 @@ static const struct xfs_btree_ops xfs_finobt_ops = {
 	.keys_inorder		= xfs_inobt_keys_inorder,
 	.recs_inorder		= xfs_inobt_recs_inorder,
 #endif
-
-	.get_leaf_keys		= xfs_btree_get_leaf_keys,
-	.get_node_keys		= xfs_btree_get_node_keys,
-	.update_keys		= xfs_btree_update_keys,
 };
 
 /*
diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
index 232450c..bc1faeb 100644
--- a/fs/xfs/libxfs/xfs_rmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rmap_btree.c
@@ -453,10 +453,6 @@ static const struct xfs_btree_ops xfs_rmapbt_ops = {
 	.keys_inorder		= xfs_rmapbt_keys_inorder,
 	.recs_inorder		= xfs_rmapbt_recs_inorder,
 #endif
-
-	.get_leaf_keys		= xfs_btree_get_leaf_keys_overlapped,
-	.get_node_keys		= xfs_btree_get_node_keys_overlapped,
-	.update_keys		= xfs_btree_update_keys_overlapped,
 };
 
 /*