[XFS] implement generic xfs_btree_split
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.
SGI-PV: 985583
SGI-Modid: xfs-linux-melb:xfs-kern:32198a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Bill O'Donnell <billodo@sgi.com>
Signed-off-by: David Chinner <david@fromorbit.com>
diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c
index 2b0d142..8057669 100644
--- a/fs/xfs/xfs_btree.c
+++ b/fs/xfs/xfs_btree.c
@@ -988,6 +988,48 @@
}
}
+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_magic = cpu_to_be32(xfs_magics[cur->bc_btnum]);
+ new->bb_level = cpu_to_be16(level);
+ new->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
@@ -1012,6 +1054,21 @@
return 1;
}
+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,
@@ -1051,6 +1108,31 @@
}
}
+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.
@@ -2199,3 +2281,189 @@
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, xfs_btree_get_level(left), 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 = xfs_btree_key_addr(cur, src_index, left);
+ lpp = xfs_btree_ptr_addr(cur, src_index, left);
+ rkp = xfs_btree_key_addr(cur, 1, right);
+ rpp = xfs_btree_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
+
+ xfs_btree_copy_keys(cur, rkp, lkp, rrecs);
+ xfs_btree_copy_ptrs(cur, rpp, lpp, rrecs);
+
+ xfs_btree_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 */
+ xfs_btree_copy_keys(cur, key, rkp, 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 = xfs_btree_rec_addr(cur, src_index, left);
+ rrp = xfs_btree_rec_addr(cur, 1, right);
+
+ xfs_btree_copy_recs(cur, rrp, lrp, rrecs);
+ xfs_btree_log_recs(cur, rbp, 1, rrecs);
+
+ cur->bc_ops->init_key_from_rec(key,
+ xfs_btree_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;
+}