Btrfs: Add fsx-style randomized tree tester

Add debug-tree command to print the tree
Add extent-tree.c to the repo
Comment ctree.h

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 296 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
new file mode 100644
index 00000000000..2b663ef8449
--- /dev/null
+++ b/fs/btrfs/extent-tree.c
@@ -0,0 +1,296 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "kerncompat.h"
+#include "radix-tree.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "print-tree.h"
+
+/*
+ * pending extents are blocks that we're trying to allocate in the extent
+ * map while trying to grow the map because of other allocations.  To avoid
+ * recursing, they are tagged in the radix tree and cleaned up after
+ * other allocations are done.  The pending tag is also used in the same
+ * manner for deletes.
+ */
+#define CTREE_EXTENT_PENDING 0
+
+/*
+ * find all the blocks marked as pending in the radix tree and remove
+ * them from the extent map
+ */
+static int del_pending_extents(struct ctree_root *extent_root)
+{
+        int ret;
+        struct key key;
+        struct tree_buffer *gang[4];
+        int i;
+        struct ctree_path path;
+
+        while(1) {
+                ret = radix_tree_gang_lookup_tag(&extent_root->cache_radix,
+                                                 (void **)gang, 0,
+                                                 ARRAY_SIZE(gang),
+                                                 CTREE_EXTENT_PENDING);
+                if (!ret)
+                        break;
+                for (i = 0; i < ret; i++) {
+                        key.objectid = gang[i]->blocknr;
+                        key.flags = 0;
+                        key.offset = 1;
+                        init_path(&path);
+                        ret = search_slot(extent_root, &key, &path, 0);
+                        if (ret) {
+                                print_tree(extent_root, extent_root->node);
+                                printf("unable to find %lu\n", key.objectid);
+                                BUG();
+                                // FIXME undo it and return sane
+                                return ret;
+                        }
+                        ret = del_item(extent_root, &path);
+                        if (ret) {
+                                BUG();
+                                return ret;
+                        }
+                        release_path(extent_root, &path);
+                        radix_tree_tag_clear(&extent_root->cache_radix,
+                                                gang[i]->blocknr,
+                                                CTREE_EXTENT_PENDING);
+                        tree_block_release(extent_root, gang[i]);
+                }
+        }
+        return 0;
+}
+
+/*
+ * remove an extent from the root, returns 0 on success
+ */
+int free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks)
+{
+        struct ctree_path path;
+        struct key key;
+        struct ctree_root *extent_root = root->extent_root;
+        struct tree_buffer *t;
+        int pending_ret;
+        int ret;
+        key.objectid = blocknr;
+        key.flags = 0;
+        key.offset = num_blocks;
+        if (root == extent_root) {
+                t = read_tree_block(root, key.objectid);
+                radix_tree_tag_set(&root->cache_radix, key.objectid,
+                                   CTREE_EXTENT_PENDING);
+                return 0;
+        }
+        init_path(&path);
+        ret = search_slot(extent_root, &key, &path, 0);
+        if (ret) {
+                print_tree(extent_root, extent_root->node);
+                printf("failed to find %lu\n", key.objectid);
+                BUG();
+        }
+        ret = del_item(extent_root, &path);
+        if (ret)
+                BUG();
+        release_path(extent_root, &path);
+        pending_ret = del_pending_extents(root->extent_root);
+        return ret ? ret : pending_ret;
+}
+
+/*
+ * walks the btree of allocated extents and find a hole of a given size.
+ * The key ins is changed to record the hole:
+ * ins->objectid == block start
+ * ins->flags = 0
+ * ins->offset == number of blocks
+ * Any available blocks before search_start are skipped.
+ */
+int find_free_extent(struct ctree_root *orig_root, u64 num_blocks,
+                     u64 search_start, u64 search_end, struct key *ins)
+{
+        struct ctree_path path;
+        struct key *key;
+        int ret;
+        u64 hole_size = 0;
+        int slot = 0;
+        u64 last_block;
+        int start_found;
+        struct leaf *l;
+        struct ctree_root * root = orig_root->extent_root;
+
+check_failed:
+        init_path(&path);
+        ins->objectid = search_start;
+        ins->offset = 0;
+        ins->flags = 0;
+        start_found = 0;
+        ret = search_slot(root, ins, &path, 0);
+        while (1) {
+                l = &path.nodes[0]->leaf;
+                slot = path.slots[0];
+                if (slot >= l->header.nritems) {
+                        ret = next_leaf(root, &path);
+                        if (ret == 0)
+                                continue;
+                        if (!start_found) {
+                                ins->objectid = search_start;
+                                ins->offset = num_blocks;
+                                start_found = 1;
+                                goto check_pending;
+                        }
+                        ins->objectid = last_block > search_start ?
+                                        last_block : search_start;
+                        ins->offset = num_blocks;
+                        goto check_pending;
+                }
+                key = &l->items[slot].key;
+                if (key->objectid >= search_start) {
+                        if (start_found) {
+                                hole_size = key->objectid - last_block;
+                                if (hole_size > num_blocks) {
+                                        ins->objectid = last_block;
+                                        ins->offset = num_blocks;
+                                        goto check_pending;
+                                }
+                        } else
+                                start_found = 1;
+                        last_block = key->objectid + key->offset;
+                }
+                path.slots[0]++;
+        }
+        // FIXME -ENOSPC
+check_pending:
+        /* we have to make sure we didn't find an extent that has already
+         * been allocated by the map tree or the original allocation
+         */
+        release_path(root, &path);
+        BUG_ON(ins->objectid < search_start);
+        if (orig_root->extent_root == orig_root) {
+                BUG_ON(num_blocks != 1);
+                if ((root->current_insert.objectid <= ins->objectid &&
+                    root->current_insert.objectid +
+                    root->current_insert.offset > ins->objectid) ||
+                   (root->current_insert.objectid > ins->objectid &&
+                    root->current_insert.objectid <= ins->objectid +
+                    ins->offset) ||
+                   radix_tree_tag_get(&root->cache_radix, ins->objectid,
+                                      CTREE_EXTENT_PENDING)) {
+                        search_start = ins->objectid + 1;
+                        goto check_failed;
+                }
+        }
+        if (ins->offset != 1)
+                BUG();
+        return 0;
+}
+
+/*
+ * insert all of the pending extents reserved during the original
+ * allocation.  (CTREE_EXTENT_PENDING).  Returns zero if it all worked out
+ */
+static int insert_pending_extents(struct ctree_root *extent_root)
+{
+        int ret;
+        struct key key;
+        struct extent_item item;
+        struct tree_buffer *gang[4];
+        int i;
+
+        // FIXME -ENOSPC
+        item.refs = 1;
+        item.owner = extent_root->node->node.header.parentid;
+        while(1) {
+                ret = radix_tree_gang_lookup_tag(&extent_root->cache_radix,
+                                                 (void **)gang, 0,
+                                                 ARRAY_SIZE(gang),
+                                                 CTREE_EXTENT_PENDING);
+                if (!ret)
+                        break;
+                for (i = 0; i < ret; i++) {
+                        key.objectid = gang[i]->blocknr;
+                        key.flags = 0;
+                        key.offset = 1;
+                        ret = insert_item(extent_root, &key, &item,
+                                          sizeof(item));
+                        if (ret) {
+                                BUG();
+                                // FIXME undo it and return sane
+                                return ret;
+                        }
+                        radix_tree_tag_clear(&extent_root->cache_radix,
+                                             gang[i]->blocknr,
+                                             CTREE_EXTENT_PENDING);
+                        tree_block_release(extent_root, gang[i]);
+                }
+        }
+        return 0;
+}
+
+/*
+ * finds a free extent and does all the dirty work required for allocation
+ * returns the key for the extent through ins, and a tree buffer for
+ * the first block of the extent through buf.
+ *
+ * returns 0 if everything worked, non-zero otherwise.
+ */
+int alloc_extent(struct ctree_root *root, u64 num_blocks, u64 search_start,
+                         u64 search_end, u64 owner, struct key *ins,
+                         struct tree_buffer **buf)
+{
+        int ret;
+        int pending_ret;
+        struct extent_item extent_item;
+        extent_item.refs = 1;
+        extent_item.owner = owner;
+
+        ret = find_free_extent(root, num_blocks, search_start, search_end, ins);
+        if (ret)
+                return ret;
+        if (root != root->extent_root) {
+                memcpy(&root->extent_root->current_insert, ins, sizeof(*ins));
+                ret = insert_item(root->extent_root, ins, &extent_item,
+                                  sizeof(extent_item));
+                memset(&root->extent_root->current_insert, 0,
+                       sizeof(struct key));
+                pending_ret = insert_pending_extents(root->extent_root);
+                if (ret)
+                        return ret;
+                if (pending_ret)
+                        return pending_ret;
+                *buf = find_tree_block(root, ins->objectid);
+                return 0;
+        }
+        /* we're allocating an extent for the extent tree, don't recurse */
+        BUG_ON(ins->offset != 1);
+        *buf = find_tree_block(root, ins->objectid);
+        BUG_ON(!*buf);
+        radix_tree_tag_set(&root->cache_radix, ins->objectid,
+                           CTREE_EXTENT_PENDING);
+        (*buf)->count++;
+        return 0;
+
+}
+
+/*
+ * helper function to allocate a block for a given tree
+ * returns the tree buffer or NULL.
+ */
+struct tree_buffer *alloc_free_block(struct ctree_root *root)
+{
+        struct key ins;
+        int ret;
+        struct tree_buffer *buf = NULL;
+
+        ret = alloc_extent(root, 1, 0, (unsigned long)-1,
+                           root->node->node.header.parentid,
+                           &ins, &buf);
+
+        if (ret) {
+                BUG();
+                return NULL;
+        }
+        if (root != root->extent_root)
+                BUG_ON(radix_tree_tag_get(&root->extent_root->cache_radix,
+                                          buf->blocknr, CTREE_EXTENT_PENDING));
+        return buf;
+}