marko10_000
/
btrfs-progs
forked from Mirrors/btrfs-progs
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

btrfs-progs: check/lowmem: Reset path in repair mode to avoid incorrect item from being passed to lowmem check. 

In lowmem mode, we check fs roots and free space cache by iterating
each root item and inode item, using btrfs_next_item() and a path
pointing to the root tree.

However in repair mode, check_fs_root() can modify the fs root, thus
CoWs the tree root, and the old path in check_fs

It could lead to strange behavior, e.g. after repairing a fs tree, the
path can point to a fs tree.
Since no ROOT_ITEM exists in fs tree, all remaining trees are skipped in
repair mode.

This bug exists from the early time of lowmem mode repair, and is only
exposed by recent free space inode check code. (Fs tree inodes are
passed to free space inode check, causing false alerts and repair
failure).

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
master
Qu Wenruo 2019-05-17 22:00:03 +08:00 committed by David Sterba
parent 085445e793
commit 48248693cd
1 changed files with 21 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
check/mode-lowmem.c
View File

@ -5203,6 +5203,27 @@ int check_fs_roots_lowmem(struct btrfs_fs_info *fs_info)
err |= ret;
}
next:
/*
* In repair mode, our path is no longer reliable as CoW can
* happen. We need to reset our path.
*/
if (repair) {
btrfs_release_path(&path);
ret = btrfs_search_slot(NULL, tree_root, &key, &path,
0, 0);
if (ret < 0) {
if (!err)
err = ret;
goto out;
}
if (ret > 0) {
/* Key not found, but already at next item */
if (path.slots[0] <
btrfs_header_nritems(path.nodes[0]))
continue;
/* falls through to next leaf */
}
}
ret = btrfs_next_item(tree_root, &path);
if (ret > 0)
goto out;