Jan Schmidt
2013-Mar-20 13:38 UTC
[PATCH] Btrfs: fix locking on ROOT_REPLACE operations in tree mod log
To resolve backrefs, ROOT_REPLACE operations in the tree mod log are
required to be tied to at least one KEY_REMOVE_WHILE_FREEING operation.
Therefore, those operations must be enclosed by tree_mod_log_write_lock()
and tree_mod_log_write_unlock() calls.
Those calls are private to the tree_mod_log_* functions, which means that
removal of the elements of an old root node must be logged from
tree_mod_log_insert_root. This partly reverts and corrects commit ba1bfbd5
(Btrfs: fix a tree mod logging issue for root replacement operations).
This fixes the brand-new version of xfstest 276 as of commit cfe73f71.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
---
Has probably been Reported-by: Alex Lyakas <alex.btrfs@zadarastorage.com>
(unconfirmed).
fs/btrfs/ctree.c | 30 ++++++++++++++++++++----------
1 files changed, 20 insertions(+), 10 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index aa50952..9dfc74a 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -763,6 +763,8 @@ pr_debug("MLL: tree mod seq list %p empty\n",
&fs_info->tree_mod_seq_list);
return 0;
}
+ __tree_mod_log_free_eb(fs_info, old_root);
+
ret = tree_mod_alloc(fs_info, flags, &tm);
if (ret < 0)
goto out;
@@ -859,7 +861,7 @@ tree_mod_log_search(struct btrfs_fs_info *fs_info, u64
start, u64 min_seq)
static noinline void
tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
struct extent_buffer *src, unsigned long dst_offset,
- unsigned long src_offset, int nr_items)
+ unsigned long src_offset, int nr_items, int log_removal)
{
int ret;
int i;
@@ -873,10 +875,12 @@ tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct
extent_buffer *dst,
}
for (i = 0; i < nr_items; i++) {
- ret = tree_mod_log_insert_key_locked(fs_info, src,
- i + src_offset,
- MOD_LOG_KEY_REMOVE);
- BUG_ON(ret < 0);
+ if (log_removal) {
+ ret = tree_mod_log_insert_key_locked(fs_info, src,
+ i + src_offset,
+ MOD_LOG_KEY_REMOVE);
+ BUG_ON(ret < 0);
+ }
ret = tree_mod_log_insert_key_locked(fs_info, dst,
i + dst_offset,
MOD_LOG_KEY_ADD);
@@ -1050,7 +1054,6 @@ static noinline int update_ref_for_cow(struct
btrfs_trans_handle *trans,
ret = btrfs_dec_ref(trans, root, buf, 1, 1);
BUG_ON(ret); /* -ENOMEM */
}
- tree_mod_log_free_eb(root->fs_info, buf);
clean_tree_block(trans, root, buf);
*last_ref = 1;
}
@@ -1171,6 +1174,7 @@ DONE_mod_log("setting a new root: %llu ->
%llu\n", root->node->start, cow->start
btrfs_set_node_ptr_generation(parent, parent_slot,
trans->transid);
btrfs_mark_buffer_dirty(parent);
+ tree_mod_log_free_eb(root->fs_info, buf);
btrfs_free_tree_block(trans, root, buf, parent_start,
last_ref);
}
@@ -1901,7 +1905,6 @@ DONE_mod_log("promoting %llu as replacement root for
almost empty %llu, tree dep
}
DONE_mod_log("new root is %llu\n", child->start);
- tree_mod_log_free_eb(root->fs_info, root->node);
tree_mod_log_set_root_pointer(root, child);
rcu_assign_pointer(root->node, child);
@@ -3210,7 +3213,7 @@ static int push_node_left(struct btrfs_trans_handle
*trans,
push_items = min(src_nritems - 8, push_items);
tree_mod_log_eb_copy(root->fs_info, dst, src, dst_nritems, 0,
- push_items);
+ push_items, 1);
copy_extent_buffer(dst, src,
btrfs_node_key_ptr_offset(dst_nritems),
btrfs_node_key_ptr_offset(0),
@@ -3283,7 +3286,7 @@ static int balance_node_right(struct btrfs_trans_handle
*trans,
DONE_mod_log("pushing %d items from %llu (now has %d) to %llu (now has
%d)\n", push_items, src->start, src_nritems - push_items, dst->start,
dst_nritems + push_items);
tree_mod_log_eb_copy(root->fs_info, dst, src, 0,
- src_nritems - push_items, push_items);
+ src_nritems - push_items, push_items, 1);
copy_extent_buffer(dst, src,
btrfs_node_key_ptr_offset(0),
btrfs_node_key_ptr_offset(src_nritems - push_items),
@@ -3436,6 +3439,7 @@ static noinline int split_node(struct btrfs_trans_handle
*trans,
int mid;
int ret;
u32 c_nritems;
+ int tree_mod_log_removal = 1;
c = path->nodes[level];
DONE_mod_log("%llu\n", c->start);
@@ -3443,6 +3447,11 @@ DONE_mod_log("%llu\n", c->start);
if (c == root->node) {
/* trying to split the root, lets make a new one */
ret = insert_new_root(trans, root, path, level + 1);
+ /*
+ * removal of root nodes has been logged by
+ * tree_mod_log_set_root_pointer due to locking
+ */
+ tree_mod_log_removal = 0;
if (ret)
return ret;
} else {
@@ -3481,7 +3490,8 @@ DONE_mod_log("buffer %llu, middle key (%llu %u %llu),
split buffer %llu. nritems
(unsigned long)btrfs_header_chunk_tree_uuid(split),
BTRFS_UUID_SIZE);
- tree_mod_log_eb_copy(root->fs_info, split, c, 0, mid, c_nritems - mid);
+ tree_mod_log_eb_copy(root->fs_info, split, c, 0, mid, c_nritems - mid,
+ tree_mod_log_removal);
copy_extent_buffer(split, c,
btrfs_node_key_ptr_offset(0),
btrfs_node_key_ptr_offset(mid),
--
1.7.1
--
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