From c974c4642fee8c58239c7753d0bf548b23799923 Mon Sep 17 00:00:00 2001 From: Wang Shilong Date: Wed, 11 Dec 2013 19:29:51 +0800 Subject: [PATCH] Btrfs: fix an oops when doing balance relocation I hit an oops when inserting reloc root into @reloc_root_tree(it can be easily triggered when forcing cow for relocation root) [ 866.494539] [] btrfs_init_reloc_root+0x79/0xb0 [btrfs] [ 866.495321] [] record_root_in_trans+0xb0/0x110 [btrfs] [ 866.496109] [] btrfs_record_root_in_trans+0x48/0x80 [btrfs] [ 866.496908] [] select_reloc_root+0xa8/0x210 [btrfs] [ 866.497703] [] do_relocation+0x16a/0x540 [btrfs] This is because reloc root inserted into @reloc_root_tree is not within one transaction,reloc root may be cowed and root block bytenr will be reused then oops happens.We should update reloc root in @reloc_root_tree when cow reloc root node, fix it. Signed-off-by: Wang Shilong Reviewed-by: Miao Xie Signed-off-by: Chris Mason --- fs/btrfs/relocation.c | 70 ++++++++++++++++++++++++++++++++++----------------- 1 file changed, 47 insertions(+), 23 deletions(-) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index ce459a7cb16d..7cdc76007c6c 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -1264,10 +1264,10 @@ static int __must_check __add_reloc_root(struct btrfs_root *root) } /* - * helper to update/delete the 'address of tree root -> reloc tree' + * helper to delete the 'address of tree root -> reloc tree' * mapping */ -static int __update_reloc_root(struct btrfs_root *root, int del) +static void __del_reloc_root(struct btrfs_root *root) { struct rb_node *rb_node; struct mapping_node *node = NULL; @@ -1275,7 +1275,7 @@ static int __update_reloc_root(struct btrfs_root *root, int del) spin_lock(&rc->reloc_root_tree.lock); rb_node = tree_search(&rc->reloc_root_tree.rb_root, - root->commit_root->start); + root->node->start); if (rb_node) { node = rb_entry(rb_node, struct mapping_node, rb_node); rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root); @@ -1283,23 +1283,45 @@ static int __update_reloc_root(struct btrfs_root *root, int del) spin_unlock(&rc->reloc_root_tree.lock); if (!node) - return 0; + return; BUG_ON((struct btrfs_root *)node->data != root); - if (!del) { - spin_lock(&rc->reloc_root_tree.lock); - node->bytenr = root->node->start; - rb_node = tree_insert(&rc->reloc_root_tree.rb_root, - node->bytenr, &node->rb_node); - spin_unlock(&rc->reloc_root_tree.lock); - if (rb_node) - backref_tree_panic(rb_node, -EEXIST, node->bytenr); - } else { - spin_lock(&root->fs_info->trans_lock); - list_del_init(&root->root_list); - spin_unlock(&root->fs_info->trans_lock); - kfree(node); + spin_lock(&root->fs_info->trans_lock); + list_del_init(&root->root_list); + spin_unlock(&root->fs_info->trans_lock); + kfree(node); +} + +/* + * helper to update the 'address of tree root -> reloc tree' + * mapping + */ +static int __update_reloc_root(struct btrfs_root *root, u64 new_bytenr) +{ + struct rb_node *rb_node; + struct mapping_node *node = NULL; + struct reloc_control *rc = root->fs_info->reloc_ctl; + + spin_lock(&rc->reloc_root_tree.lock); + rb_node = tree_search(&rc->reloc_root_tree.rb_root, + root->node->start); + if (rb_node) { + node = rb_entry(rb_node, struct mapping_node, rb_node); + rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root); } + spin_unlock(&rc->reloc_root_tree.lock); + + if (!node) + return 0; + BUG_ON((struct btrfs_root *)node->data != root); + + spin_lock(&rc->reloc_root_tree.lock); + node->bytenr = new_bytenr; + rb_node = tree_insert(&rc->reloc_root_tree.rb_root, + node->bytenr, &node->rb_node); + spin_unlock(&rc->reloc_root_tree.lock); + if (rb_node) + backref_tree_panic(rb_node, -EEXIST, node->bytenr); return 0; } @@ -1420,7 +1442,6 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans, { struct btrfs_root *reloc_root; struct btrfs_root_item *root_item; - int del = 0; int ret; if (!root->reloc_root) @@ -1432,11 +1453,9 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans, if (root->fs_info->reloc_ctl->merge_reloc_tree && btrfs_root_refs(root_item) == 0) { root->reloc_root = NULL; - del = 1; + __del_reloc_root(reloc_root); } - __update_reloc_root(reloc_root, del); - if (reloc_root->commit_root != reloc_root->node) { btrfs_set_root_node(root_item, reloc_root->node); free_extent_buffer(reloc_root->commit_root); @@ -2287,7 +2306,7 @@ void free_reloc_roots(struct list_head *list) while (!list_empty(list)) { reloc_root = list_entry(list->next, struct btrfs_root, root_list); - __update_reloc_root(reloc_root, 1); + __del_reloc_root(reloc_root); free_extent_buffer(reloc_root->node); free_extent_buffer(reloc_root->commit_root); kfree(reloc_root); @@ -2332,7 +2351,7 @@ again: ret = merge_reloc_root(rc, root); if (ret) { - __update_reloc_root(reloc_root, 1); + __del_reloc_root(reloc_root); free_extent_buffer(reloc_root->node); free_extent_buffer(reloc_root->commit_root); kfree(reloc_root); @@ -4522,6 +4541,11 @@ int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans, BUG_ON(rc->stage == UPDATE_DATA_PTRS && root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID); + if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) { + if (buf == root->node) + __update_reloc_root(root, cow->start); + } + level = btrfs_header_level(buf); if (btrfs_header_generation(buf) <= btrfs_root_last_snapshot(&root->root_item)) -- 2.11.0