[PATCH 6/8] xfs: hoist the node iroot update code out of xfs_btree_new_iroot

Darrick J. Wong
2024-12-13T00:59:33Z

From: Darrick J. Wong <djwong@kernel.org>

In preparation for allowing records in an inode btree root, hoist the
code that copies keyptrs from an existing node root into a child block
to a separate function. Note that the new function explicitly computes
the keys of the new child block and stores that in the root block; while
the bmap btree could rely on leaving the key alone, realtime rmap needs
to set the new high key.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
fs/xfs/libxfs/xfs_btree.c | 117 +++++++++++++++++++++++++++++----------------
1 file changed, 76 insertions(+), 41 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 672746f7217cff..ed09eeee916160 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -3078,6 +3078,78 @@ xfs_btree_split(
#define xfs_btree_split __xfs_btree_split
#endif /* __KERNEL__ */

+/*
+ * Move the keys and pointers from a root block to a separate block.
+ *
+ * Since the keyptr size does not change, all we have to do is increase the
+ * tree height, copy the keyptrs to the new internal node (cblock), shrink
+ * the root, and copy the pointers there.
+ */
+STATIC int
+xfs_btree_promote_node_iroot(
+ struct xfs_btree_cur *cur,
+ struct xfs_btree_block *block,
+ int level,
+ struct xfs_buf *cbp,
+ union xfs_btree_ptr *cptr,
+ struct xfs_btree_block *cblock)
+{
+ union xfs_btree_key *ckp;
+ union xfs_btree_key *kp;
+ union xfs_btree_ptr *cpp;
+ union xfs_btree_ptr *pp;
+ int i;
+ int error;
+ int numrecs = xfs_btree_get_numrecs(block);
+
+ /*
+ * Increase tree height, adjusting the root block level to match.
+ * We cannot change the root btree node size until we've copied the
+ * block contents to the new child block.
+ */
+ be16_add_cpu(&block->bb_level, 1);
+ cur->bc_nlevels++;
+ cur->bc_levels[level + 1].ptr = 1;
+
+ /*
+ * Adjust the root btree record count, then copy the keys from the old
+ * root to the new child block.
+ */
+ xfs_btree_set_numrecs(block, 1);
+ kp = xfs_btree_key_addr(cur, 1, block);
+ ckp = xfs_btree_key_addr(cur, 1, cblock);
+ xfs_btree_copy_keys(cur, ckp, kp, numrecs);
+
+ /* Check the pointers and copy them to the new child block. */
+ pp = xfs_btree_ptr_addr(cur, 1, block);
+ cpp = xfs_btree_ptr_addr(cur, 1, cblock);
+ for (i = 0; i < numrecs; i++) {
+ error = xfs_btree_debug_check_ptr(cur, pp, i, level);
+ if (error)
+ return error;
+ }
+ xfs_btree_copy_ptrs(cur, cpp, pp, numrecs);
+
+ /*
+ * Set the first keyptr to point to the new child block, then shrink
+ * the memory buffer for the root block.
+ */
+ error = xfs_btree_debug_check_ptr(cur, cptr, 0, level);
+ if (error)
+ return error;
+ xfs_btree_copy_ptrs(cur, pp, cptr, 1);
+ xfs_btree_get_keys(cur, cblock, kp);
+
+ cur->bc_ops->broot_realloc(cur, 1);
+
+ /* Attach the new block to the cursor and log it. */
+ xfs_btree_setbuf(cur, level, cbp);
+ xfs_btree_log_block(cur, cbp, XFS_BB_ALL_BITS);
+ xfs_btree_log_keys(cur, cbp, 1, numrecs);
+ xfs_btree_log_ptrs(cur, cbp, 1, numrecs);
+ return 0;
+}
+
/*
* Copy the old inode root contents into a real block and make the
* broot point to it.
@@ -3091,14 +3163,10 @@ xfs_btree_new_iroot(
struct xfs_buf *cbp; /* buffer for cblock */
struct xfs_btree_block *block; /* btree block */
struct xfs_btree_block *cblock; /* child btree block */
- union xfs_btree_key *ckp; /* child key pointer */
- union xfs_btree_ptr *cpp; /* child ptr pointer */
- union xfs_btree_key *kp; /* pointer to btree key */
- union xfs_btree_ptr *pp; /* pointer to block addr */
+ union xfs_btree_ptr *pp;
union xfs_btree_ptr nptr; /* new block addr */
int level; /* btree level */
int error; /* error return code */
- int i; /* loop counter */

XFS_BTREE_STATS_INC(cur, newroot);

@@ -3136,45 +3204,12 @@ xfs_btree_new_iroot(
cblock->bb_u.s.bb_blkno = bno;
}

- be16_add_cpu(&block->bb_level, 1);
- xfs_btree_set_numrecs(block, 1);
- cur->bc_nlevels++;
- ASSERT(cur->bc_nlevels <= cur->bc_maxlevels);
- cur->bc_levels[level + 1].ptr = 1;
-
- kp = xfs_btree_key_addr(cur, 1, block);
- ckp = xfs_btree_key_addr(cur, 1, cblock);
- xfs_btree_copy_keys(cur, ckp, kp, xfs_btree_get_numrecs(cblock));
-
- cpp = xfs_btree_ptr_addr(cur, 1, cblock);
- for (i = 0; i < be16_to_cpu(cblock->bb_numrecs); i++) {
- error = xfs_btree_debug_check_ptr(cur, pp, i, level);
- if (error)
- goto error0;
- }
-
- xfs_btree_copy_ptrs(cur, cpp, pp, xfs_btree_get_numrecs(cblock));
-
- error = xfs_btree_debug_check_ptr(cur, &nptr, 0, level);
+ error = xfs_btree_promote_node_iroot(cur, block, level, cbp, &nptr,
+ cblock);
if (error)
goto error0;

- xfs_btree_copy_ptrs(cur, pp, &nptr, 1);
-
- cur->bc_ops->broot_realloc(cur, 1);
-
- xfs_btree_setbuf(cur, level, cbp);
-
- /*
- * Do all this logging at the end so that
- * the root is at the right level.
- */
- xfs_btree_log_block(cur, cbp, XFS_BB_ALL_BITS);
- xfs_btree_log_keys(cur, cbp, 1, be16_to_cpu(cblock->bb_numrecs));
- xfs_btree_log_ptrs(cur, cbp, 1, be16_to_cpu(cblock->bb_numrecs));
-
- *logflags |=
- XFS_ILOG_CORE | xfs_ilog_fbroot(cur->bc_ino.whichfork);
+ *logflags |= XFS_ILOG_CORE | xfs_ilog_fbroot(cur->bc_ino.whichfork);
*stat = 1;
return 0;
error0: