Wang Shilong
2013-Dec-11 11:29 UTC
[PATCH v2 1/2] 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] [<ffffffffa0499579>] btrfs_init_reloc_root+0x79/0xb0
[btrfs]
[ 866.495321] [<ffffffffa044c240>] record_root_in_trans+0xb0/0x110
[btrfs]
[ 866.496109] [<ffffffffa044d758>] btrfs_record_root_in_trans+0x48/0x80
[btrfs]
[ 866.496908] [<ffffffffa0494da8>] select_reloc_root+0xa8/0x210 [btrfs]
[ 866.497703] [<ffffffffa0495c8a>] 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 <wangsl.fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
---
v1->v2: on the right way to fix this problem.
---
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 4c56444..55bffcf 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -1266,10 +1266,10 @@ 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;
@@ -1277,7 +1277,7 @@ 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);
@@ -1285,23 +1285,45 @@ 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;
}
@@ -1422,7 +1444,6 @@ 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)
@@ -1434,11 +1455,9 @@ 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);
@@ -2289,7 +2308,7 @@ 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);
@@ -2334,7 +2353,7 @@ 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);
@@ -4520,6 +4539,11 @@ 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))
--
1.8.3.1
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Wang Shilong
2013-Dec-11 11:29 UTC
[PATCH] Btrfs: make sure we cleanup all reloc roots if error happens
I hit an oops when merging reloc roots fails, the reason is that new reloc roots may be added and we should make sure we cleanup all reloc roots. Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com> --- fs/btrfs/relocation.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 55bffcf..93d01b7 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -2409,6 +2409,13 @@ out: btrfs_std_error(root->fs_info, ret); if (!list_empty(&reloc_roots)) free_reloc_roots(&reloc_roots); + + /* new reloc root may be added */ + mutex_lock(&root->fs_info->reloc_mutex); + list_splice_init(&rc->reloc_roots, &reloc_roots); + mutex_unlock(&root->fs_info->reloc_mutex); + if (!list_empty(&reloc_roots)) + free_reloc_roots(&reloc_roots); } BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root)); -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html