[XFS] implement generic xfs_btree_lshift
Make the btree left shift 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:32197a
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 e1a2137..2b0d142 100644
--- a/fs/xfs/xfs_btree.c
+++ b/fs/xfs/xfs_btree.c
@@ -1841,6 +1841,191 @@
}
/*
+ * Move 1 record left from cur/level if possible.
+ * Update cur to reflect the new path.
+ */
+int /* error */
+xfs_btree_lshift(
+ struct xfs_btree_cur *cur,
+ int level,
+ int *stat) /* success/failure */
+{
+ union xfs_btree_key key; /* btree key */
+ struct xfs_buf *lbp; /* left buffer pointer */
+ struct xfs_btree_block *left; /* left btree block */
+ int lrecs; /* left record count */
+ struct xfs_buf *rbp; /* right buffer pointer */
+ struct xfs_btree_block *right; /* right btree block */
+ int rrecs; /* right record count */
+ union xfs_btree_ptr lptr; /* left btree pointer */
+ union xfs_btree_key *rkp = NULL; /* right btree key */
+ union xfs_btree_ptr *rpp = NULL; /* right address pointer */
+ union xfs_btree_rec *rrp = NULL; /* right record pointer */
+ int error; /* error return value */
+
+ XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+ XFS_BTREE_TRACE_ARGI(cur, level);
+
+ if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
+ level == cur->bc_nlevels - 1)
+ goto out0;
+
+ /* Set up variables for this block as "right". */
+ right = xfs_btree_get_block(cur, level, &rbp);
+
+#ifdef DEBUG
+ error = xfs_btree_check_block(cur, right, level, rbp);
+ if (error)
+ goto error0;
+#endif
+
+ /* If we've got no left sibling then we can't shift an entry left. */
+ xfs_btree_get_sibling(cur, right, &lptr, XFS_BB_LEFTSIB);
+ if (xfs_btree_ptr_is_null(cur, &lptr))
+ goto out0;
+
+ /*
+ * If the cursor entry is the one that would be moved, don't
+ * do it... it's too complicated.
+ */
+ if (cur->bc_ptrs[level] <= 1)
+ goto out0;
+
+ /* Set up the left neighbor as "left". */
+ error = xfs_btree_read_buf_block(cur, &lptr, level, 0, &left, &lbp);
+ if (error)
+ goto error0;
+
+ /* If it's full, it can't take another entry. */
+ lrecs = xfs_btree_get_numrecs(left);
+ if (lrecs == cur->bc_ops->get_maxrecs(cur, level))
+ goto out0;
+
+ rrecs = xfs_btree_get_numrecs(right);
+
+ /*
+ * We add one entry to the left side and remove one for the right side.
+ * Accout for it here, the changes will be updated on disk and logged
+ * later.
+ */
+ lrecs++;
+ rrecs--;
+
+ XFS_BTREE_STATS_INC(cur, lshift);
+ XFS_BTREE_STATS_ADD(cur, moves, 1);
+
+ /*
+ * If non-leaf, copy a key and a ptr to the left block.
+ * Log the changes to the left block.
+ */
+ 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 */
+
+ lkp = xfs_btree_key_addr(cur, lrecs, left);
+ rkp = xfs_btree_key_addr(cur, 1, right);
+
+ lpp = xfs_btree_ptr_addr(cur, lrecs, left);
+ rpp = xfs_btree_ptr_addr(cur, 1, right);
+#ifdef DEBUG
+ error = xfs_btree_check_ptr(cur, rpp, 0, level);
+ if (error)
+ goto error0;
+#endif
+ xfs_btree_copy_keys(cur, lkp, rkp, 1);
+ xfs_btree_copy_ptrs(cur, lpp, rpp, 1);
+
+ xfs_btree_log_keys(cur, lbp, lrecs, lrecs);
+ xfs_btree_log_ptrs(cur, lbp, lrecs, lrecs);
+
+ xfs_btree_check_key(cur->bc_btnum,
+ xfs_btree_key_addr(cur, lrecs - 1, left),
+ lkp);
+ } else {
+ /* It's a leaf. Move records. */
+ union xfs_btree_rec *lrp; /* left record pointer */
+
+ lrp = xfs_btree_rec_addr(cur, lrecs, left);
+ rrp = xfs_btree_rec_addr(cur, 1, right);
+
+ xfs_btree_copy_recs(cur, lrp, rrp, 1);
+ xfs_btree_log_recs(cur, lbp, lrecs, lrecs);
+
+ xfs_btree_check_rec(cur->bc_btnum,
+ xfs_btree_rec_addr(cur, lrecs - 1, left),
+ lrp);
+ }
+
+ xfs_btree_set_numrecs(left, lrecs);
+ xfs_btree_log_block(cur, lbp, XFS_BB_NUMRECS);
+
+ xfs_btree_set_numrecs(right, rrecs);
+ xfs_btree_log_block(cur, rbp, XFS_BB_NUMRECS);
+
+ /*
+ * Slide the contents of right down one entry.
+ */
+ XFS_BTREE_STATS_ADD(cur, moves, rrecs - 1);
+ if (level > 0) {
+ /* It's a nonleaf. operate on keys and ptrs */
+#ifdef DEBUG
+ int i; /* loop index */
+
+ for (i = 0; i < rrecs; i++) {
+ error = xfs_btree_check_ptr(cur, rpp, i + 1, level);
+ if (error)
+ goto error0;
+ }
+#endif
+ xfs_btree_shift_keys(cur,
+ xfs_btree_key_addr(cur, 2, right),
+ -1, rrecs);
+ xfs_btree_shift_ptrs(cur,
+ xfs_btree_ptr_addr(cur, 2, right),
+ -1, rrecs);
+
+ xfs_btree_log_keys(cur, rbp, 1, rrecs);
+ xfs_btree_log_ptrs(cur, rbp, 1, rrecs);
+ } else {
+ /* It's a leaf. operate on records */
+ xfs_btree_shift_recs(cur,
+ xfs_btree_rec_addr(cur, 2, right),
+ -1, rrecs);
+ xfs_btree_log_recs(cur, rbp, 1, rrecs);
+
+ /*
+ * If it's the first record in the block, we'll need a key
+ * structure to pass up to the next level (updkey).
+ */
+ cur->bc_ops->init_key_from_rec(&key,
+ xfs_btree_rec_addr(cur, 1, right));
+ rkp = &key;
+ }
+
+ /* Update the parent key values of right. */
+ error = xfs_btree_updkey(cur, rkp, level + 1);
+ if (error)
+ goto error0;
+
+ /* Slide the cursor value left one. */
+ cur->bc_ptrs[level]--;
+
+ 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;
+}
+
+/*
* Move 1 record right from cur/level if possible.
* Update cur to reflect the new path.
*/