From: Kent Overstreet <kent.overstreet@linux.dev>
To: Guoyu Ou <benogy@gmail.com>
Cc: linux-bcachefs@vger.kernel.org
Subject: Re: [PATCH v3] bcachefs: skip invisible entries in empty subvolume checking
Date: Thu, 15 Feb 2024 19:26:13 -0500 [thread overview]
Message-ID: <w65bwhlqu6uakz63kmiz5uxp5pvifblcjdf6xyk72db4jgksss@oiichpxg52as> (raw)
In-Reply-To: <ZcxlXyHP8evlVLUB@ousvr>
On Wed, Feb 14, 2024 at 03:03:15PM +0800, Guoyu Ou wrote:
> 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 <benogy@gmail.com>
> > > ---
> > > 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.
You're right, I think it was just late when I was staring at this the
first time.
> 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() ?
nah, let's not overcomplicate this - maybe I'll add a comment but
otherwise I'll just apply this - thanks
>
> >
> > > 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
> > >
prev parent reply other threads:[~2024-02-16 0:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-13 8:20 [PATCH v3] bcachefs: skip invisible entries in empty subvolume checking Guoyu Ou
2024-02-14 2:38 ` Kent Overstreet
2024-02-14 7:03 ` Guoyu Ou
2024-02-16 0:26 ` Kent Overstreet [this message]
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