MIRRORS/linux-yocto
1
0
Fork 0
mirror of git://git.yoctoproject.org/linux-yocto.git synced 2025-10-22 23:13:01 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity

bcachefs: Fix subvol to missing root repair

Browse Source 
We had a bug where the root inode of a subvolume was erronously deleted:
bch2_evict_inode() called bch2_inode_rm(), meaning the VFS inode's
i_nlink was somehow set to 0 when it shouldn't have - the inode in the
btree indicated it clearly was not unlinked.

This has been addressed with additional safety checks in
bch2_inode_rm() - pulling in the safety checks we already were doing
when deleting unlinked inodes in recovery - but the really disastrous
bug was in check_subvols(), which on finding a dangling subvol (subvol
with a missing root inode) would delete the subvolume.

I assume this bug dates from early check_directory_structure() code,
which originally handled subvolumes and normal paths - the idea being
that still live contents of the subvolume would get reattached
somewhere.

But that's incorrect, and disastrously so; deleting a subvolume triggers
deleting the snapshot ID it points to, deleting the entire contents.

The correct way to repair is to recreate the root inode if it's missing;
then any contents will get reattached under that subvolume's lost+found.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2025-06-02 19:48:27 -04:00
parent 09fb85ae56
commit 29cc6fb7c0
1 changed files with 14 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
fs/bcachefs/subvolume.c
View File

@ -130,10 +130,20 @@ static int check_subvol(struct btree_trans *trans,
"subvolume %llu points to missing subvolume root %llu:%u",
k.k->p.offset, le64_to_cpu(subvol.v->inode),
le32_to_cpu(subvol.v->snapshot))) {
ret = bch2_subvolume_delete(trans, iter->pos.offset);
bch_err_msg(c, ret, "deleting subvolume %llu", iter->pos.offset);
ret = ret ?: -BCH_ERR_transaction_restart_nested;
goto err;
/*
* Recreate - any contents that are still disconnected
* will then get reattached under lost+found
*/
bch2_inode_init_early(c, &inode);
bch2_inode_init_late(c, &inode, bch2_current_time(c),
0, 0, S_IFDIR|0700, 0, NULL);
inode.bi_inum = le64_to_cpu(subvol.v->inode);
inode.bi_snapshot = le32_to_cpu(subvol.v->snapshot);
inode.bi_subvol = k.k->p.offset;
inode.bi_parent_subvol = le32_to_cpu(subvol.v->fs_path_parent);
ret = __bch2_fsck_write_inode(trans, &inode);
if (ret)
goto err;
}
} else {
goto err;