sorry for cc linux-bcachefs...
On Tue, Feb 13, 2024 at 09:38:39PM -0500, Kent Overstreet wrote:
> On Tue, Feb 13, 2024 at 04:20:04PM +0800, Guoyu Ou wrote:
> > When we are checking whether a subvolume is empty in the specified snapshot,
> > entries that do not belong to this subvolume should be skipped.
> >
> > This fixes the following case:
> >
> > $ bcachefs subvolume create ./sub
> > $ cd sub
> > $ bcachefs subvolume create ./sub2
> > $ bcachefs subvolume snapshot . ./snap
> > $ ls -a snap
> > . ..
> > $ rmdir snap
> > rmdir: failed to remove 'snap': Directory not empty
> >
> > As Kent suggested, we pass 0 in may_delete_deleted_inode() to ignore subvols
> > in the subvol we are checking, because inode.bi_subvol is only set on
> > subvolume roots, and we can't go through every inode in the subvolume and
> > change bi_subvol when taking a snapshot. It makes the check less strict, but
> > that's ok, the rest of fsck will still catch it.
> >
> > Signed-off-by: Guoyu Ou <[email protected]>
> > ---
> > fs/bcachefs/dirent.c | 7 +++++--
> > fs/bcachefs/dirent.h | 2 +-
> > fs/bcachefs/inode.c | 2 +-
> > 3 files changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/bcachefs/dirent.c b/fs/bcachefs/dirent.c
> > index 4ae1e9f002a0..82c5bff01411 100644
> > --- a/fs/bcachefs/dirent.c
> > +++ b/fs/bcachefs/dirent.c
> > @@ -508,7 +508,7 @@ u64 bch2_dirent_lookup(struct bch_fs *c, subvol_inum
> > dir,
> > return ret;
> > }
> >
> > -int bch2_empty_dir_snapshot(struct btree_trans *trans, u64 dir, u32
> > snapshot)
> > +int bch2_empty_dir_snapshot(struct btree_trans *trans, u64 dir, u32
> > subvol, u32 snapshot)
> > {
> > struct btree_iter iter;
> > struct bkey_s_c k;
> > @@ -518,6 +518,9 @@ int bch2_empty_dir_snapshot(struct btree_trans *trans,
> > u64 dir, u32 snapshot)
> > SPOS(dir, 0, snapshot),
> > POS(dir, U64_MAX), 0, k, ret)
> > if (k.k->type == KEY_TYPE_dirent) {
> > + struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
> > + if (d.v->d_type == DT_SUBVOL &&
> > le32_to_cpu(d.v->d_parent_subvol) != subvol)
> > + continue;
>
>
> if (d.v->d_type == DT_SUBVOL && (le32_to_cpu(d.v->d_parent_subvol) != subvol
> || !subvol))
If 0 is an invalid value for subvolume ids, the predicate
le32_to_cpu(d.v->d_parent_subvol) != subvol
is always true for subvol == 0 and there's no need to add !subvol.
Otherwise, I think it's better to add a flag to indicate whether we are
checking subvol in
bch2_empty_dir_snapshot(), like
int bch2_empty_dir_snapshot(struct btree_trans *, u64 dir, u32 subvol, bool
check_subvol, u32 snapshot)
{
...
if (d.v->d_type == DT_SUBVOL && (check_subvol &&
le32_to_cpu(d.v->d_parent_subvol) != subvol))
}
or can we use a different helper function, rather than
bch2_empty_dir_snapshot(), for may_delete_deleted_inode() ?
>
> > ret = -ENOTEMPTY;
> > break;
> > }
> > @@ -531,7 +534,7 @@ int bch2_empty_dir_trans(struct btree_trans *trans,
> > subvol_inum dir)
> > u32 snapshot;
> >
> > return bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot) ?:
> > - bch2_empty_dir_snapshot(trans, dir.inum, snapshot);
> > + bch2_empty_dir_snapshot(trans, dir.inum, dir.subvol, snapshot);
> > }
> >
> > int bch2_readdir(struct bch_fs *c, subvol_inum inum, struct dir_context
> > *ctx)
> > diff --git a/fs/bcachefs/dirent.h b/fs/bcachefs/dirent.h
> > index 21ffeb78f02e..aeb8207ca9f2 100644
> > --- a/fs/bcachefs/dirent.h
> > +++ b/fs/bcachefs/dirent.h
> > @@ -69,7 +69,7 @@ u64 bch2_dirent_lookup(struct bch_fs *, subvol_inum,
> > const struct bch_hash_info *,
> > const struct qstr *, subvol_inum *);
> >
> > -int bch2_empty_dir_snapshot(struct btree_trans *, u64, u32);
> > +int bch2_empty_dir_snapshot(struct btree_trans *, u64, u32, u32);
> > int bch2_empty_dir_trans(struct btree_trans *, subvol_inum);
> > int bch2_readdir(struct bch_fs *, subvol_inum, struct dir_context *);
> >
> > diff --git a/fs/bcachefs/inode.c b/fs/bcachefs/inode.c
> > index 086f0090b03a..84a6e5011032 100644
> > --- a/fs/bcachefs/inode.c
> > +++ b/fs/bcachefs/inode.c
> > @@ -1088,7 +1088,7 @@ static int may_delete_deleted_inode(struct
> > btree_trans *trans,
> > goto out;
> >
> > if (S_ISDIR(inode.bi_mode)) {
> > - ret = bch2_empty_dir_snapshot(trans, pos.offset, pos.snapshot);
> > + ret = bch2_empty_dir_snapshot(trans, pos.offset, 0,
> > pos.snapshot);
> > if (fsck_err_on(ret == -ENOTEMPTY, c, deleted_inode_is_dir,
> > "non empty directory %llu:%u in deleted_inodes
> > btree",
> > pos.offset, pos.snapshot))
> > --
> > 2.43.0
> >
