diff options
| author | Josef Bacik <josef@toxicpanda.com> | 2020-03-04 19:18:24 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2020-03-23 19:01:57 +0300 |
| commit | 2abc726ab4b83db774e315c660ab8da21477092f (patch) | |
| tree | 026a25254b297d0b984a33940c6475b1d1e7447c /fs/btrfs | |
| parent | 6217b0fadd4473a16fabc6aecd7527a9f71af534 (diff) | |
| download | linux-2abc726ab4b83db774e315c660ab8da21477092f.tar.xz | |
btrfs: do not init a reloc root if we aren't relocating
We previously were checking if the root had a dead root before accessing
root->reloc_root in order to avoid a use-after-free type bug. However
this scenario happens after we've unset the reloc control, so we would
have been saved if we'd simply checked for fs_info->reloc_control. At
this point during relocation we no longer need to be creating new reloc
roots, so simply move this check above the reloc_root checks to avoid
any future races and confusion.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/relocation.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index d2069d69fc92..631f94085ba6 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -1511,6 +1511,10 @@ int btrfs_init_reloc_root(struct btrfs_trans_handle *trans, int clear_rsv = 0; int ret; + if (!rc || !rc->create_reloc_tree || + root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) + return 0; + /* * The subvolume has reloc tree but the swap is finished, no need to * create/update the dead reloc tree @@ -1524,10 +1528,6 @@ int btrfs_init_reloc_root(struct btrfs_trans_handle *trans, return 0; } - if (!rc || !rc->create_reloc_tree || - root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) - return 0; - if (!trans->reloc_reserved) { rsv = trans->block_rsv; trans->block_rsv = rc->block_rsv; @@ -2369,6 +2369,18 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc, trans = NULL; goto out; } + + /* + * At this point we no longer have a reloc_control, so we can't + * depend on btrfs_init_reloc_root to update our last_trans. + * + * But that's ok, we started the trans handle on our + * corresponding fs_root, which means it's been added to the + * dirty list. At commit time we'll still call + * btrfs_update_reloc_root() and update our root item + * appropriately. + */ + reloc_root->last_trans = trans->transid; trans->block_rsv = rc->block_rsv; replaced = 0; |