Commit ec9cc18f authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Add checks for invalid snapshot IDs 



Previously, we assumed that keys were consistent with the snapshots
btree - but that's not correct as fsck may not have been run or may not
be complete.

This adds checks and error handling when using the in-memory snapshots
table (that mirrors the snapshots btree).

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent 63332394

fs/bcachefs/btree_trans_commit.c

+1 −1
Original line number Diff line number Diff line
@@ -318,7 +318,7 @@ static inline void btree_insert_entry_checks(struct btree_trans *trans, 
		!(i->flags & BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) &&

		test_bit(JOURNAL_REPLAY_DONE, &trans->c->journal.flags) &&

		i->k->k.p.snapshot &&

		bch2_snapshot_is_internal_node(trans->c, i->k->k.p.snapshot));

		bch2_snapshot_is_internal_node(trans->c, i->k->k.p.snapshot) > 0);

}



static __always_inline int bch2_trans_journal_res_get(struct btree_trans *trans,

fs/bcachefs/data_update.c

+9 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include "move.h"

#include "nocow_locking.h"

#include "rebalance.h"

#include "snapshot.h"

#include "subvolume.h"

#include "trace.h"
@@ -509,6 +510,14 @@ int bch2_data_update_init(struct btree_trans *trans, 
	unsigned ptrs_locked = 0;

	int ret = 0;



	/*

	 * fs is corrupt  we have a key for a snapshot node that doesn't exist,

	 * and we have to check for this because we go rw before repairing the

	 * snapshots table - just skip it, we can move it later.

	 */

	if (unlikely(k.k->p.snapshot && !bch2_snapshot_equiv(c, k.k->p.snapshot)))

		return -BCH_ERR_data_update_done;



	bch2_bkey_buf_init(&m->k);

	bch2_bkey_buf_reassemble(&m->k, c, k);

	m->btree_id	= btree_id;

fs/bcachefs/errcode.h

+2 −1
Original line number Diff line number Diff line
@@ -252,7 +252,8 @@ 
	x(BCH_ERR_nopromote,		nopromote_in_flight)			\

	x(BCH_ERR_nopromote,		nopromote_no_writes)			\

	x(BCH_ERR_nopromote,		nopromote_enomem)			\

	x(0,				need_inode_lock)

	x(0,				need_inode_lock)			\

	x(0,				invalid_snapshot_node)



enum bch_errcode {

	BCH_ERR_START		= 2048,

fs/bcachefs/snapshot.c

+6 −2
Original line number Diff line number Diff line
@@ -93,8 +93,10 @@ static int bch2_snapshot_tree_create(struct btree_trans *trans, 


static bool __bch2_snapshot_is_ancestor_early(struct snapshot_table *t, u32 id, u32 ancestor)

{

	while (id && id < ancestor)

		id = __snapshot_t(t, id)->parent;

	while (id && id < ancestor) {

		const struct snapshot_t *s = __snapshot_t(t, id);

		id = s ? s->parent : 0;

	}

	return id == ancestor;

}
@@ -110,6 +112,8 @@ static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancest 
static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ancestor)

{

	const struct snapshot_t *s = __snapshot_t(t, id);

	if (!s)

		return 0;



	if (s->skip[2] <= ancestor)

		return s->skip[2];

fs/bcachefs/snapshot.h

+22 −35
Original line number Diff line number Diff line
@@ -48,7 +48,8 @@ static inline const struct snapshot_t *snapshot_t(struct bch_fs *c, u32 id) 
static inline u32 bch2_snapshot_tree(struct bch_fs *c, u32 id)

{

	rcu_read_lock();

	id = snapshot_t(c, id)->tree;

	const struct snapshot_t *s = snapshot_t(c, id);

	id = s ? s->tree : 0;

	rcu_read_unlock();



	return id;
@@ -56,7 +57,8 @@ static inline u32 bch2_snapshot_tree(struct bch_fs *c, u32 id) 


static inline u32 __bch2_snapshot_parent_early(struct bch_fs *c, u32 id)

{

	return snapshot_t(c, id)->parent;

	const struct snapshot_t *s = snapshot_t(c, id);

	return s ? s->parent : 0;

}



static inline u32 bch2_snapshot_parent_early(struct bch_fs *c, u32 id)
@@ -70,19 +72,19 @@ static inline u32 bch2_snapshot_parent_early(struct bch_fs *c, u32 id) 


static inline u32 __bch2_snapshot_parent(struct bch_fs *c, u32 id)

{

#ifdef CONFIG_BCACHEFS_DEBUG

	u32 parent = snapshot_t(c, id)->parent;

	const struct snapshot_t *s = snapshot_t(c, id);

	if (!s)

		return 0;



	if (parent &&

	    snapshot_t(c, id)->depth != snapshot_t(c, parent)->depth + 1)

	u32 parent = s->parent;

	if (IS_ENABLED(CONFIG_BCACHEFS_DEBU) &&

	    parent &&

	    s->depth != snapshot_t(c, parent)->depth + 1)

		panic("id %u depth=%u parent %u depth=%u\n",

		      id, snapshot_t(c, id)->depth,

		      parent, snapshot_t(c, parent)->depth);



	return parent;

#else

	return snapshot_t(c, id)->parent;

#endif

}



static inline u32 bch2_snapshot_parent(struct bch_fs *c, u32 id)
@@ -120,7 +122,8 @@ static inline u32 bch2_snapshot_root(struct bch_fs *c, u32 id) 


static inline u32 __bch2_snapshot_equiv(struct bch_fs *c, u32 id)

{

	return snapshot_t(c, id)->equiv;

	const struct snapshot_t *s = snapshot_t(c, id);

	return s ? s->equiv : 0;

}



static inline u32 bch2_snapshot_equiv(struct bch_fs *c, u32 id)
@@ -137,38 +140,22 @@ static inline bool bch2_snapshot_is_equiv(struct bch_fs *c, u32 id) 
	return id == bch2_snapshot_equiv(c, id);

}



static inline bool bch2_snapshot_is_internal_node(struct bch_fs *c, u32 id)

static inline int bch2_snapshot_is_internal_node(struct bch_fs *c, u32 id)

{

	const struct snapshot_t *s;

	bool ret;



	rcu_read_lock();

	s = snapshot_t(c, id);

	ret = s->children[0];

	const struct snapshot_t *s = snapshot_t(c, id);

	int ret = s ? s->children[0] : -BCH_ERR_invalid_snapshot_node;

	rcu_read_unlock();



	return ret;

}



static inline u32 bch2_snapshot_is_leaf(struct bch_fs *c, u32 id)

{

	return !bch2_snapshot_is_internal_node(c, id);

}



static inline u32 bch2_snapshot_sibling(struct bch_fs *c, u32 id)

static inline int bch2_snapshot_is_leaf(struct bch_fs *c, u32 id)

{

	const struct snapshot_t *s;

	u32 parent = __bch2_snapshot_parent(c, id);



	if (!parent)

		return 0;



	s = snapshot_t(c, __bch2_snapshot_parent(c, id));

	if (id == s->children[0])

		return s->children[1];

	if (id == s->children[1])

		return s->children[0];

	return 0;

	int ret = bch2_snapshot_is_internal_node(c, id);

	if (ret < 0)

		return ret;

	return !ret;

}



static inline u32 bch2_snapshot_depth(struct bch_fs *c, u32 parent)
@@ -253,7 +240,7 @@ static inline int bch2_key_has_snapshot_overwrites(struct btree_trans *trans, 
					  struct bpos pos)

{

	if (!btree_type_has_snapshots(id) ||

	    bch2_snapshot_is_leaf(trans->c, pos.snapshot))

	    bch2_snapshot_is_leaf(trans->c, pos.snapshot) > 0)

		return 0;



	return __bch2_key_has_snapshot_overwrites(trans, id, pos);