For the tree mod log, we don't log any operations at leaf level. If the root is at the leaf level (i.e. the tree consists only of the root), then __tree_mod_log_oldest_root will find a ROOT_REPLACE operation in the log (because we always log that one no matter which level), but no other operations. With this patch __tree_mod_log_oldest_root exits cleanly instead of BUGging in this situation. get_old_root checks if its really a root at leaf level in case we don't have any operations and WARNs if this assumption breaks. Signed-off-by: Jan Schmidt <list.btrfs@xxxxxxxxxxxxx> --- fs/btrfs/ctree.c | 28 +++++++++++++++------------- 1 files changed, 15 insertions(+), 13 deletions(-) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 15cbc2b..7d1e4fc 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1024,11 +1024,18 @@ __tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info, if (!looped && !tm) return 0; /* - * we must have key remove operations in the log before the - * replace operation. + * if there are no tree operation for the oldest root, we simply + * return it. this should only happen if that (old) root is at + * level 0. */ - BUG_ON(!tm); + if (!tm) + break; + /* + * if there's an operation that's not a root replacement, we + * found the oldest version of our root. normally, we'll find a + * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here. + */ if (tm->op != MOD_LOG_ROOT_REPLACE) break; @@ -1192,16 +1199,8 @@ get_old_root(struct btrfs_root *root, u64 time_seq) } tm = tree_mod_log_search(root->fs_info, logical, time_seq); - /* - * there was an item in the log when __tree_mod_log_oldest_root - * returned. this one must not go away, because the time_seq passed to - * us must be blocking its removal. - */ - BUG_ON(!tm); - if (old_root) - eb = alloc_dummy_extent_buffer(tm->index << PAGE_CACHE_SHIFT, - root->nodesize); + eb = alloc_dummy_extent_buffer(logical, root->nodesize); else eb = btrfs_clone_extent_buffer(root->node); btrfs_tree_read_unlock(root->node); @@ -1216,7 +1215,10 @@ get_old_root(struct btrfs_root *root, u64 time_seq) btrfs_set_header_level(eb, old_root->level); btrfs_set_header_generation(eb, old_generation); } - __tree_mod_log_rewind(eb, time_seq, tm); + if (tm) + __tree_mod_log_rewind(eb, time_seq, tm); + else + WARN_ON(btrfs_header_level(eb) != 0); extent_buffer_get(eb); return eb; -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
