hello, This patch makes btrfs_run_delayed_refs processes delayed back reference insertion before deletion. This prevents the reference count in BTRFS_EXTENT_ITEM going down to zero when there still are pending delayed back references. This patch fixes the issue that BTRFS_EXTENT_ITEM with zero reference count left in the extent tree. Thank you,
Signed-off-by: Yan Zheng <[email protected]> --- diff -urp 1/fs/btrfs/extent-tree.c 2/fs/btrfs/extent-tree.c --- 1/fs/btrfs/extent-tree.c 2009-02-23 09:02:35.763717851 +0800 +++ 2/fs/btrfs/extent-tree.c 2009-02-23 21:20:08.000000000 +0800 @@ -1533,6 +1533,37 @@ static noinline int run_one_delayed_ref( return 0; } +static noinline struct btrfs_delayed_ref_node * +select_delayed_ref(struct btrfs_delayed_ref_head *head) +{ + struct rb_node *node; + struct btrfs_delayed_ref_node *ref; + int action = BTRFS_ADD_DELAYED_REF; +again: + /* + * select delayed ref of type BTRFS_ADD_DELAYED_REF first. + * this prevents ref count from going down to zero when + * there still are pending delayed ref. + */ + node = rb_prev(&head->node.rb_node); + while (1) { + if (!node) + break; + ref = rb_entry(node, struct btrfs_delayed_ref_node, + rb_node); + if (ref->bytenr != head->node.bytenr) + break; + if (btrfs_delayed_node_to_ref(ref)->action == action) + return ref; + node = rb_prev(node); + } + if (action == BTRFS_ADD_DELAYED_REF) { + action = BTRFS_DROP_DELAYED_REF; + goto again; + } + return NULL; +} + /* * this starts processing the delayed reference count updates and * extent insertions we have queued up so far. count can be @@ -1592,23 +1623,13 @@ again: * locked_ref is the head node, so we have to go one * node back for any delayed ref updates */ - node = rb_prev(&locked_ref->node.rb_node); - if (node) { - ref = rb_entry(node, struct btrfs_delayed_ref_node, - rb_node); - /* if the byte numbers don't match, there are - * no updates for this head node. Go ahead - * and send the head node to run_one_delayed_ref + + ref = select_delayed_ref(locked_ref); + if (!ref) { + /* All delayed refs have been processed, Go ahead + * and send the head node to run_one_delayed_ref, * so that any accounting fixes can happen */ - if (ref->bytenr != locked_ref->node.bytenr) { - ref = &locked_ref->node; - locked_ref = NULL; - } - } else { - /* there is no previous node at all, just - * process the head ref - */ ref = &locked_ref->node; locked_ref = NULL; } @@ -2996,7 +3017,6 @@ static int __free_extent(struct btrfs_tr int extent_slot = 0; int found_extent = 0; int num_to_del = 1; - int cache_pending; struct btrfs_extent_item *ei; u32 refs; @@ -3065,14 +3085,13 @@ static int __free_extent(struct btrfs_tr * we're not allowed to delete the extent item if there * are other delayed ref updates pending */ - cache_pending = btrfs_delayed_ref_pending(trans, bytenr); BUG_ON(refs < refs_to_drop); refs -= refs_to_drop; btrfs_set_extent_refs(leaf, ei, refs); btrfs_mark_buffer_dirty(leaf); - if (!cache_pending && refs == 0 && found_extent && + if (refs == 0 && found_extent && path->slots[0] == extent_slot + 1) { struct btrfs_extent_ref *ref; ref = btrfs_item_ptr(leaf, path->slots[0], @@ -3089,7 +3108,7 @@ static int __free_extent(struct btrfs_tr refs_to_drop); BUG_ON(ret); /* if refs are 0, we need to setup the path for deletion */ - if (refs == 0 && !cache_pending) { + if (refs == 0) { btrfs_release_path(extent_root, path); ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1); @@ -3097,7 +3116,7 @@ static int __free_extent(struct btrfs_tr } } - if (!cache_pending && refs == 0) { + if (refs == 0) { u64 super_used; u64 root_used; -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
