On Fri, Apr 06, 2018 at 02:39:19PM +0800, Qu Wenruo wrote:
> Corrupted extent tree (either the root node or leaf) can normally block
> us from open the fs.
> As normally open_ctree() has the following call chain:
> __open_ctree_fd()
> |- btrfs_setup_all_roots()
> |- btrfs_read_block_groups()
> And we will search block group items in extent tree.
>
> And considering how block group items are scattered around the whole
> extent tree, any error would block the fs from being mounted.
>
> Fortunately, we already have OPEN_CTREE_NO_BLOCK_GROUPS flags to disable
> block group items search, which will not only allow us to open some
> fs, but also hugely speed up open time.
>
> Currently dump-tree and btrfs-restore is ensured that they care nothing
> about block group items. So specify OPEN_CTREE_NO_BLOCK_GROUPS flag as
> default.
>
> Also fix a typo where dump-tree is using OPEN_CTREE_FS_PARTIAL, which
> should be OPEN_CTREE_PARTIAL.
> This makes dump-tree do more check and can sometimes fail to open
> certain filesystems.
Oh, that's too easy to get wrong, we should rename one or the other.
> Reported-by: Christoph Anton Mitterer <cales...@scientia.net>
> Fixes: 8698a2b9ba89 ("btrfs-progs: Allow inspect dump-tree to show specified
> tree block even some tree roots are corrupted")
> Signed-off-by: Qu Wenruo <w...@suse.com>
> ---
> cmds-inspect-dump-tree.c | 4 +++-
> cmds-restore.c | 3 ++-
> 2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/cmds-inspect-dump-tree.c b/cmds-inspect-dump-tree.c
> index 7defb7164a49..8be976041543 100644
> --- a/cmds-inspect-dump-tree.c
> +++ b/cmds-inspect-dump-tree.c
> @@ -303,7 +303,9 @@ int cmd_inspect_dump_tree(int argc, char **argv)
> int uuid_tree_only = 0;
> int roots_only = 0;
> int root_backups = 0;
> - unsigned open_ctree_flags = OPEN_CTREE_FS_PARTIAL;
> + /* Speed up open_ctree() and continue if extent tree is corrupted */
> + unsigned open_ctree_flags = OPEN_CTREE_PARTIAL |
> + OPEN_CTREE_NO_BLOCK_GROUPS;
We could consider that separatelly, whether to allow dumping a partially
created filesystem, ie. OPEN_CTREE_FS_PARTIAL added by a new option.
This would be really for debugging/testing purposes, but could be useful
when the filesystem is prefilled with files or if we enable the runtime
features and the final write fails for some reason.
> u64 block_bytenr;
> struct btrfs_root *tree_root_scan;
> u64 tree_id = 0;
> diff --git a/cmds-restore.c b/cmds-restore.c
> index ade35f0f880f..b43bd2ac6502 100644
> --- a/cmds-restore.c
> +++ b/cmds-restore.c
> @@ -1282,7 +1282,8 @@ static struct btrfs_root *open_fs(const char *dev, u64
> root_location,
> for (i = super_mirror; i < BTRFS_SUPER_MIRROR_MAX; i++) {
> bytenr = btrfs_sb_offset(i);
> fs_info = open_ctree_fs_info(dev, bytenr, root_location, 0,
> - OPEN_CTREE_PARTIAL);
> + OPEN_CTREE_PARTIAL |
> + OPEN_CTREE_NO_BLOCK_GROUPS);
> if (fs_info)
> break;
> fprintf(stderr, "Could not open root, trying backup super\n");
--
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