Btrfs: do not reuse objectid of deleted snapshot/subvol
The new back reference format does not allow reusing objectid of
deleted snapshot/subvol. So we use ++highest_objectid to allocate
objectid for new snapshot/subvol.
Now we use ++highest_objectid to allocate objectid for both new inode
and new snapshot/subvolume, so this patch removes 'find hole' code in
btrfs_find_free_objectid.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
index 9abbced..c56eb59 100644
--- a/fs/btrfs/inode-map.c
+++ b/fs/btrfs/inode-map.c
@@ -43,9 +43,10 @@
slot = path->slots[0] - 1;
l = path->nodes[0];
btrfs_item_key_to_cpu(l, &found_key, slot);
- *objectid = found_key.objectid;
+ *objectid = max_t(u64, found_key.objectid,
+ BTRFS_FIRST_FREE_OBJECTID - 1);
} else {
- *objectid = BTRFS_FIRST_FREE_OBJECTID;
+ *objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
}
ret = 0;
error:
@@ -53,91 +54,27 @@
return ret;
}
-/*
- * walks the btree of allocated inodes and find a hole.
- */
int btrfs_find_free_objectid(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 dirid, u64 *objectid)
{
- struct btrfs_path *path;
- struct btrfs_key key;
int ret;
- int slot = 0;
- u64 last_ino = 0;
- int start_found;
- struct extent_buffer *l;
- struct btrfs_key search_key;
- u64 search_start = dirid;
-
mutex_lock(&root->objectid_mutex);
- if (root->last_inode_alloc >= BTRFS_FIRST_FREE_OBJECTID &&
- root->last_inode_alloc < BTRFS_LAST_FREE_OBJECTID) {
- *objectid = ++root->last_inode_alloc;
- mutex_unlock(&root->objectid_mutex);
- return 0;
+
+ if (unlikely(root->highest_objectid < BTRFS_FIRST_FREE_OBJECTID)) {
+ ret = btrfs_find_highest_inode(root, &root->highest_objectid);
+ if (ret)
+ goto out;
}
- path = btrfs_alloc_path();
- BUG_ON(!path);
- search_start = max(search_start, (u64)BTRFS_FIRST_FREE_OBJECTID);
- search_key.objectid = search_start;
- search_key.type = 0;
- search_key.offset = 0;
- start_found = 0;
- ret = btrfs_search_slot(trans, root, &search_key, path, 0, 0);
- if (ret < 0)
- goto error;
-
- while (1) {
- l = path->nodes[0];
- slot = path->slots[0];
- if (slot >= btrfs_header_nritems(l)) {
- ret = btrfs_next_leaf(root, path);
- if (ret == 0)
- continue;
- if (ret < 0)
- goto error;
- if (!start_found) {
- *objectid = search_start;
- start_found = 1;
- goto found;
- }
- *objectid = last_ino > search_start ?
- last_ino : search_start;
- goto found;
- }
- btrfs_item_key_to_cpu(l, &key, slot);
- if (key.objectid >= search_start) {
- if (start_found) {
- if (last_ino < search_start)
- last_ino = search_start;
- if (key.objectid > last_ino) {
- *objectid = last_ino;
- goto found;
- }
- } else if (key.objectid > search_start) {
- *objectid = search_start;
- goto found;
- }
- }
- if (key.objectid >= BTRFS_LAST_FREE_OBJECTID)
- break;
-
- start_found = 1;
- last_ino = key.objectid + 1;
- path->slots[0]++;
+ if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
+ ret = -ENOSPC;
+ goto out;
}
- BUG_ON(1);
-found:
- btrfs_release_path(root, path);
- btrfs_free_path(path);
- BUG_ON(*objectid < search_start);
- mutex_unlock(&root->objectid_mutex);
- return 0;
-error:
- btrfs_release_path(root, path);
- btrfs_free_path(path);
+
+ *objectid = ++root->highest_objectid;
+ ret = 0;
+out:
mutex_unlock(&root->objectid_mutex);
return ret;
}