Commit 63332394 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Move snapshot table size to struct snapshot_table 



We need to add bounds checking for snapshot table accesses - it turns
out there are cases where we do need to use the snapshots table before
fsck checks have completed (and indeed, fsck may not have been run).

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent aa6e130e

fs/bcachefs/bcachefs.h

+0 −1
Original line number Diff line number Diff line
@@ -810,7 +810,6 @@ struct bch_fs { 


	/* snapshot.c: */

	struct snapshot_table __rcu *snapshots;

	size_t			snapshot_table_size;

	struct mutex		snapshot_table_lock;

	struct rw_semaphore	snapshot_create_lock;

fs/bcachefs/snapshot.c

+14 −11
Original line number Diff line number Diff line
@@ -151,36 +151,39 @@ bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor) 
static noinline struct snapshot_t *__snapshot_t_mut(struct bch_fs *c, u32 id)

{

	size_t idx = U32_MAX - id;

	size_t new_size;

	struct snapshot_table *new, *old;



	new_size = max(16UL, roundup_pow_of_two(idx + 1));

	size_t new_bytes = kmalloc_size_roundup(struct_size(new, s, idx + 1));

	size_t new_size = (new_bytes - sizeof(*new)) / sizeof(new->s[0]);



	new = kvzalloc(struct_size(new, s, new_size), GFP_KERNEL);

	new = kvzalloc(new_bytes, GFP_KERNEL);

	if (!new)

		return NULL;



	new->nr = new_size;



	old = rcu_dereference_protected(c->snapshots, true);

	if (old)

		memcpy(new->s,

		       rcu_dereference_protected(c->snapshots, true)->s,

		       sizeof(new->s[0]) * c->snapshot_table_size);

		memcpy(new->s, old->s, sizeof(old->s[0]) * old->nr);



	rcu_assign_pointer(c->snapshots, new);

	c->snapshot_table_size = new_size;

	kvfree_rcu_mightsleep(old);

	kvfree_rcu(old, rcu);



	return &rcu_dereference_protected(c->snapshots, true)->s[idx];

	return &rcu_dereference_protected(c->snapshots,

				lockdep_is_held(&c->snapshot_table_lock))->s[idx];

}



static inline struct snapshot_t *snapshot_t_mut(struct bch_fs *c, u32 id)

{

	size_t idx = U32_MAX - id;

	struct snapshot_table *table =

		rcu_dereference_protected(c->snapshots,

				lockdep_is_held(&c->snapshot_table_lock));



	lockdep_assert_held(&c->snapshot_table_lock);



	if (likely(idx < c->snapshot_table_size))

		return &rcu_dereference_protected(c->snapshots, true)->s[idx];

	if (likely(table && idx < table->nr))

		return &table->s[idx];



	return __snapshot_t_mut(c, id);

}

fs/bcachefs/snapshot.h

+5 −1
Original line number Diff line number Diff line
@@ -33,7 +33,11 @@ int bch2_mark_snapshot(struct btree_trans *, enum btree_id, unsigned, 


static inline struct snapshot_t *__snapshot_t(struct snapshot_table *t, u32 id)

{

	return &t->s[U32_MAX - id];

	u32 idx = U32_MAX - id;



	return likely(t && idx < t->nr)

		? &t->s[idx]

		: NULL;

}



static inline const struct snapshot_t *snapshot_t(struct bch_fs *c, u32 id)

fs/bcachefs/subvolume_types.h

+2 −0
Original line number Diff line number Diff line
@@ -20,6 +20,8 @@ struct snapshot_t { 
};



struct snapshot_table {

	struct rcu_head		rcu;

	size_t			nr;

#ifndef RUST_BINDGEN

	DECLARE_FLEX_ARRAY(struct snapshot_t, s);

#else