// SPDX-License-Identifier: GPL-2.0
#include "bcachefs.h"
#include "bkey_buf.h"
#include "btree_key_cache.h"
#include "btree_update.h"
#include "buckets.h"
#include "errcode.h"
#include "error.h"
#include "fs.h"
#include "recovery_passes.h"
#include "snapshot.h"
#include <linux/random.h>
/*
* Snapshot trees:
*
* Keys in BTREE_ID_snapshot_trees identify a whole tree of snapshot nodes; they
* exist to provide a stable identifier for the whole lifetime of a snapshot
* tree.
*/
void bch2_snapshot_tree_to_text(struct printbuf *out, struct bch_fs *c,
struct bkey_s_c k)
{
struct bkey_s_c_snapshot_tree t = bkey_s_c_to_snapshot_tree(k);
prt_printf(out, "subvol %u root snapshot %u",
le32_to_cpu(t.v->master_subvol),
le32_to_cpu(t.v->root_snapshot));
}
int bch2_snapshot_tree_validate(struct bch_fs *c, struct bkey_s_c k,
enum bch_validate_flags flags)
{
int ret = 0;
bkey_fsck_err_on(bkey_gt(k.k->p, POS(0, U32_MAX)) ||
bkey_lt(k.k->p, POS(0, 1)),
c, snapshot_tree_pos_bad,
"bad pos");
fsck_err:
return ret;
}
int bch2_snapshot_tree_lookup(struct btree_trans *trans, u32 id,
struct bch_snapshot_tree *s)
{
int ret = bch2_bkey_get_val_typed(trans, BTREE_ID_snapshot_trees, POS(0, id),
BTREE_ITER_with_updates, snapshot_tree, s);
if (bch2_err_matches(ret, ENOENT))
ret = -BCH_ERR_ENOENT_snapshot_tree;
return ret;
}
struct bkey_i_snapshot_tree *
__bch2_snapshot_tree_create(struct btree_trans *trans)
{
struct btree_iter iter;
int ret = bch2_bkey_get_empty_slot(trans, &iter,
BTREE_ID_snapshot_trees, POS(0, U32_MAX));
struct bkey_i_snapshot_tree *s_t;
if (ret == -BCH_ERR_ENOSPC_btree_slot)
ret = -BCH_ERR_ENOSPC_snapshot_tree;
if (ret)
return ERR_PTR(ret);
s_t = bch2_bkey_alloc(trans, &iter, 0, snapshot_tree);
ret = PTR_ERR_OR_ZERO(s_t);
bch2_trans_iter_exit(trans, &iter);
return ret ? ERR_PTR(ret) : s_t;
}
static int bch2_snapshot_tree_create(struct btree_trans *trans,
u32 root_id, u32 subvol_id, u32 *tree_id)
{
struct bkey_i_snapshot_tree *n_tree =
__bch2_snapshot_tree_create(trans);
if (IS_ERR(n_tree))
return PTR_ERR(n_tree);
n_tree->v.master_subvol = cpu_to_le32(subvol_id);
n_tree->v.root_snapshot = cpu_to_le32(root_id);
*tree_id = n_tree->k.p.offset;
return 0;
}
/* Snapshot nodes: */
static bool __bch2_snapshot_is_ancestor_early(struct snapshot_table *t, u32 id, u32 ancestor)
{
while (id && id < ancestor) {
const struct snapshot_t *s = __snapshot_t(t, id);
id = s ? s->parent : 0;
}
return id == ancestor;
}
static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor)
{
rcu_read_lock();
bool ret = __bch2_snapshot_is_ancestor_early(rcu_dereference(c->snapshots), id, ancestor);
rcu_read_unlock();
return ret;
}
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];
if (s->skip[1] <= ancestor)
return s->skip[1];
if (s->skip[0] <= ancestor)
return s->skip[0];
return s->parent;
}
static bool test_ancestor_bitmap(struct snapshot_table *t, u32 id, u32 ancestor)
{
const struct snapshot_t *s = __snapshot_t(t, id);
if (!s)
return false;
return test_bit(ancestor - id - 1, s->is_ancestor);
}
bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor)
{
bool ret;
rcu_read_lock();
struct snapshot_table *t = rcu_dereference(c->snapshots);
if (unlikely(c->recovery_pass_done < BCH_RECOVERY_PASS_check_snapshots)) {
ret = __bch2_snapshot_is_ancestor_early(t, id, ancestor);
goto out;
}
while (id && id < ancestor - IS_ANCESTOR_BITMAP)
id = get_ancestor_below(t, id, ancestor);
ret = id && id < ancestor
? test_ancestor_bitmap(t, id, ancestor)
: id == ancestor;
EBUG_ON(ret != __bch2_snapshot_is_ancestor_early(t, id, ancestor));
out:
rcu_read_unlock();
return ret;
}
static noinline struct snapshot_t *__snapshot_t_mut(struct bch_fs *c, u32 id)
{
size_t idx = U32_MAX - id;
struct snapshot_table *new, *old;
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]);
if (unlikely(new_bytes > INT_MAX))
return NULL;
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, old->s, sizeof(old->s[0]) * old->nr);
rcu_assign_pointer(c->snapshots, new);
kvfree_rcu(old, rcu);
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(table && idx < table->nr))
return &table->s[idx];
return __snapshot_t_mut(c, id);
}
void bch2_snapshot_to_text(struct printbuf *out, struct bch_fs *c,
struct bkey_s_c k)
{
struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(k);
prt_printf(out, "is_subvol %llu deleted %llu parent %10u children %10u %10u subvol %u tree %u",
BCH_SNAPSHOT_SUBVOL(s.v),
BCH_SNAPSHOT_DELETED(s.v),
le32_to_cpu(s.v->parent),
le32_to_cpu(s.v->children[0]),
le32_to_cpu(s.v->children[1]),
le32_to_cpu(s.v->subvol),
le32_to_cpu(s.v->tree));
if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, depth))
prt_printf(out, " depth %u skiplist %u %u %u",
le32_to_cpu(s.v->depth),
le32_to_cpu(s.v->skip[0]),
le32_to_cpu(s.v->skip[1]),
le32_to_cpu(s.v->skip[2]));
}
int bch2_snapshot_validate(struct bch_fs *c, struct bkey_s_c k,
enum bch_validate_flags flags)
{
struct bkey_s_c_snapshot s;
u32 i, id;
int ret = 0;
bkey_fsck_err_on(bkey_gt(k.k->p, POS(0, U32_MAX)) ||
bkey_lt(k.k->p, POS(0, 1)),
c, snapshot_pos_bad,
"bad pos");
s = bkey_s_c_to_snapshot(k);
id = le32_to_cpu(s.v->parent);
bkey_fsck_err_on(id && id <= k.k->p.offset,
c, snapshot_parent_bad,
"bad parent node (%u <= %llu)",
id, k.k->p.offset);
bkey_fsck_err_on(le32_to_cpu(s.v->children[0]) < le32_to_cpu(s.v->children[1]),
c, snapshot_children_not_normalized,
"children not normalized");
bkey_fsck_err_on(s.v->children[0] && s.v->children[0] == s.v->children[1],
c, snapshot_child_duplicate,
"duplicate child nodes");
for (i = 0; i < 2; i++) {
id = le32_to_cpu(s.v->children[i]);
bkey_fsck_err_on(id >= k.k->p.offset,
c, snapshot_child_bad,
"bad child node (%u >= %llu)",
id, k.k->p.offset);
}
if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, skip)) {
bkey_fsck_err_on(le32_to_cpu(s.v->skip[0]) > le32_to_cpu(s.v->skip[1]) ||
le32_to_cpu(s.v->skip[1]) > le32_to_cpu(s.v->skip[2]),
c, snapshot_skiplist_not_normalized,
"skiplist not normalized");
for (i = 0; i < ARRAY_SIZE(s.v->skip); i++) {
id = le32_to_cpu(s.v->skip[i]);
bkey_fsck_err_on(id && id < le32_to_cpu(s.v->parent),
c, snapshot_skiplist_bad,
"bad skiplist node %u", id);
}
}
fsck_err:
return ret;
}
static void __set_is_ancestor_bitmap(struct bch_fs *c, u32 id)
{
struct snapshot_t *t = snapshot_t_mut(c, id);
u32 parent = id;
while ((parent = bch2_snapshot_parent_early(c, parent)) &&
parent - id - 1 < IS_ANCESTOR_BITMAP)
__set_bit(parent - id - 1, t->is_ancestor);
}
static void set_is_ancestor_bitmap(struct bch_fs *c, u32 id)
{
mutex_lock(&c->snapshot_table_lock);
__set_is_ancestor_bitmap(c, id);
mutex_unlock(&c->snapshot_table_lock);
}
static int __bch2_mark_snapshot(struct btree_trans *trans,
enum btree_id btree, unsigned level,
struct bkey_s_c old, struct bkey_s_c new,
enum btree_iter_update_trigger_flags flags)
{
struct bch_fs *c = trans->c;
struct snapshot_t *t;
u32 id = new.k->p.offset;
int ret = 0;
mutex_lock(&c->snapshot_table_lock);
t = snapshot_t_mut(c, id);
if (!t) {
ret = -BCH_ERR_ENOMEM_mark_snapshot;
goto err;
}
if (new.k->type == KEY_TYPE_snapshot) {
struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(new);
t->parent = le32_to_cpu(s.v->parent);
t->children[0] = le32_to_cpu(s.v->children[0]);
t->children[1] = le32_to_cpu(s.v->children[1]);
t->subvol = BCH_SNAPSHOT_SUBVOL(s.v) ? le32_to_cpu(s.v->subvol) : 0;
t->tree = le32_to_cpu(s.v->tree);
if (bkey_val_bytes(s.k) > offsetof(struct bch_snapshot, depth)) {
t->depth = le32_to_cpu(s.v->depth);
t->skip[0] = le32_to_cpu(s.v->skip[0]);
t->skip[1] = le32_to_cpu(s.v->skip[1]);
t->skip[2] = le32_to_cpu(s.v->skip[2]);
} else {
t->depth = 0;
t->skip[0] = 0;
t->skip[1] = 0;
t->skip[2] = 0;
}
__set_is_ancestor_bitmap(c, id);
if (BCH_SNAPSHOT_DELETED(s.v)) {
set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags);
if (c->curr_recovery_pass > BCH_RECOVERY_PASS_delete_dead_snapshots)
bch2_delete_dead_snapshots_async(c);
}
} else {
memset(t, 0, sizeof(*t));
}
err:
mutex_unlock(&c->snapshot_table_lock);
return ret;
}
int bch2_mark_snapshot(struct btree_trans *trans,
enum btree_id btree, unsigned level,
struct bkey_s_c old, struct bkey_s new,
enum btree_iter_update_trigger_flags flags)
{
return __bch2_mark_snapshot(trans, btree, level, old, new.s_c, flags);
}
int bch2_snapshot_lookup(struct btree_trans *trans, u32 id,
struct bch_snapshot *s)
{
return bch2_bkey_get_val_typed(trans, BTREE_ID_snapshots, POS(0, id),
BTREE_ITER_with_updates, snapshot, s);
}
static int bch2_snapshot_live(struct btree_trans *trans, u32 id)
{
struct bch_snapshot v;
int ret;
if (!id)
return 0;
ret = bch2_snapshot_lookup(trans, id, &v);
if (bch2_err_matches(ret, ENOENT))
bch_err(trans->c, "snapshot node %u not found", id);
if (ret)
return ret;
return !BCH_SNAPSHOT_DELETED(&v);
}
/*
* If @k is a snapshot with just one live child, it's part of a linear chain,
* which we consider to be an equivalence class: and then after snapshot
* deletion cleanup, there should only be a single key at a given position in
* this equivalence class.
*
* This sets the equivalence class of @k to be the child's equivalence class, if
* it's part of such a linear chain: this correctly sets equivalence classes on
* startup if we run leaf to root (i.e. in natural key order).
*/
static int bch2_snapshot_set_equiv(struct btree_trans *trans, struct bkey_s_c k)
{
struct bch_fs *c = trans->c;
unsigned i, nr_live = 0, live_idx = 0;
struct bkey_s_c_snapshot snap;
u32 id = k.k->p.offset, child[2];
if (k.k->type != KEY_TYPE_snapshot)
return 0;
snap = bkey_s_c_to_snapshot(k);
child[0] = le32_to_cpu(snap.v->children[0]);
child[1] = le32_to_cpu(snap.v->children[1]);
for (i = 0; i < 2; i++) {
int ret = bch2_snapshot_live(trans, child[i]);
if (ret < 0)
return ret;
if (ret)
live_idx = i;
nr_live += ret;
}
mutex_lock(&c->snapshot_table_lock);
snapshot_t_mut(c, id)->equiv = nr_live == 1
? snapshot_t_mut(c, child[live_idx])->equiv
: id;
mutex_unlock(&c->snapshot_table_lock);
return 0;
}
/* fsck: */
static u32 bch2_snapshot_child(struct bch_fs *c, u32 id, unsigned child)
{
return snapshot_t(c, id)->children[child];
}
static u32 bch2_snapshot_left_child(struct bch_fs *c, u32 id)
{
return bch2_snapshot_child(c, id, 0);
}
static u32 bch2_snapshot_right_child(struct bch_fs *c, u32 id)
{
return bch2_snapshot_child(c, id, 1);
}
static u32 bch2_snapshot_tree_next(struct bch_fs *c, u32 id)
{
u32 n, parent;
n = bch2_snapshot_left_child(c, id);
if (n)
return n;
while ((parent = bch2_snapshot_parent(c, id))) {
n = bch2_snapshot_right_child(c, parent);
if (n && n != id)
return n;
id = parent;
}
return 0;
}
static u32 bch2_snapshot_tree_oldest_subvol(struct bch_fs *c, u32 snapshot_root)
{
u32 id = snapshot_root;
u32 subvol = 0, s;
rcu_read_lock();
while (id) {
s = snapshot_t(c, id)->subvol;
if (s && (!subvol || s < subvol))
subvol = s;
id = bch2_snapshot_tree_next(c, id);
}
rcu_read_unlock();
return subvol;
}
static int bch2_snapshot_tree_master_subvol(struct btree_trans *trans,
u32 snapshot_root, u32 *subvol_id)
{
struct bch_fs *c = trans->c;
struct btree_iter iter;
struct bkey_s_c k;
bool found = false;
int ret;
for_each_btree_key_norestart(trans, iter, BTREE_ID_subvolumes, POS_MIN,
0, k, ret) {
if (k.k->type != KEY_TYPE_subvolume)
continue;
struct bkey_s_c_subvolume s = bkey_s_c_to_subvolume(k);
if (!bch2_snapshot_is_ancestor(c, le32_to_cpu(s.v->snapshot), snapshot_root))
continue;
if (!BCH_SUBVOLUME_SNAP(s.v)) {
*subvol_id = s.k->p.offset;
found = true;
break;
}
}
bch2_trans_iter_exit(trans, &iter);
if (!ret && !found) {
struct bkey_i_subvolume *u;
*subvol_id = bch2_snapshot_tree_oldest_subvol(c, snapshot_root);
u = bch2_bkey_get_mut_typed(trans, &iter,
BTREE_ID_subvolumes, POS(0, *subvol_id),
0, subvolume);
ret = PTR_ERR_OR_ZERO(u);
if (ret)
return ret;
SET_BCH_SUBVOLUME_SNAP(&u->v, false);
}
return ret;
}
static int check_snapshot_tree(struct btree_trans *trans,
struct btree_iter *iter,
struct bkey_s_c k)
{
struct bch_fs *c = trans->c;
struct bkey_s_c_snapshot_tree st;
struct bch_snapshot s;
struct bch_subvolume subvol;
struct printbuf buf = PRINTBUF;
u32 root_id;
int ret;
if (k.k->type != KEY_TYPE_snapshot_tree)
return 0;
st = bkey_s_c_to_snapshot_tree(k);
root_id = le32_to_cpu(st.v->root_snapshot);
ret = bch2_snapshot_lookup(trans, root_id, &s);
if (ret && !bch2_err_matches(ret, ENOENT))
goto err;
if (fsck_err_on(ret ||
root_id != bch2_snapshot_root(c, root_id) ||
st.k->p.offset != le32_to_cpu(s.tree),
trans, snapshot_tree_to_missing_snapshot,
"snapshot tree points to missing/incorrect snapshot:\n %s",
(bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) {
ret = bch2_btree_delete_at(trans, iter, 0);
goto err;
}
ret = bch2_subvolume_get(trans, le32_to_cpu(st.v->master_subvol),
false, 0, &subvol);
if (ret && !bch2_err_matches(ret, ENOENT))
goto err;
if (fsck_err_on(ret,
trans, snapshot_tree_to_missing_subvol,
"snapshot tree points to missing subvolume:\n %s",
(printbuf_reset(&buf),
bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||
fsck_err_on(!bch2_snapshot_is_ancestor(c,
le32_to_cpu(subvol.snapshot),
root_id),
trans, snapshot_tree_to_wrong_subvol,
"snapshot tree points to subvolume that does not point to snapshot in this tree:\n %s",
(printbuf_reset(&buf),
bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||
fsck_err_on(BCH_SUBVOLUME_SNAP(&subvol),
trans, snapshot_tree_to_snapshot_subvol,
"snapshot tree points to snapshot subvolume:\n %s",
(printbuf_reset(&buf),
bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) {
struct bkey_i_snapshot_tree *u;
u32 subvol_id;
ret = bch2_snapshot_tree_master_subvol(trans, root_id, &subvol_id);
bch_err_fn(c, ret);
if (bch2_err_matches(ret, ENOENT)) { /* nothing to be done here */
ret = 0;
goto err;
}
if (ret)
goto err;
u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot_tree);
ret = PTR_ERR_OR_ZERO(u);
if (ret)
goto err;
u->v.master_subvol = cpu_to_le32(subvol_id);
st = snapshot_tree_i_to_s_c(u);
}
err:
fsck_err:
printbuf_exit(&buf);
return ret;
}
/*
* For each snapshot_tree, make sure it points to the root of a snapshot tree
* and that snapshot entry points back to it, or delete it.
*
* And, make sure it points to a subvolume within that snapshot tree, or correct
* it to point to the oldest subvolume within that snapshot tree.
*/
int bch2_check_snapshot_trees(struct bch_fs *c)
{
int ret = bch2_trans_run(c,
for_each_btree_key_commit(trans, iter,
BTREE_ID_snapshot_trees, POS_MIN,
BTREE_ITER_prefetch, k,
NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
check_snapshot_tree(trans, &iter, k)));
bch_err_fn(c, ret);
return ret;
}
/*
* Look up snapshot tree for @tree_id and find root,
* make sure @snap_id is a descendent:
*/
static int snapshot_tree_ptr_good(struct btree_trans *trans,
u32 snap_id, u32 tree_id)
{
struct bch_snapshot_tree s_t;
int ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);
if (bch2_err_matches(ret, ENOENT))
return 0;
if (ret)
return ret;
return bch2_snapshot_is_ancestor_early(trans->c, snap_id, le32_to_cpu(s_t.root_snapshot));
}
u32 bch2_snapshot_skiplist_get(struct bch_fs *c, u32 id)
{
const struct snapshot_t *s;
if (!id)
return 0;
rcu_read_lock();
s = snapshot_t(c, id);
if (s->parent)
id = bch2_snapshot_nth_parent(c, id, get_random_u32_below(s->depth));
rcu_read_unlock();
return id;
}
static int snapshot_skiplist_good(struct btree_trans *trans, u32 id, struct bch_snapshot s)
{
unsigned i;
for (i = 0; i < 3; i++)
if (!s.parent) {
if (s.skip[i])
return false;
} else {
if (!bch2_snapshot_is_ancestor_early(trans->c, id, le32_to_cpu(s.skip[i])))
return false;
}
return true;
}
/*
* snapshot_tree pointer was incorrect: look up root snapshot node, make sure
* its snapshot_tree pointer is correct (allocate new one if necessary), then
* update this node's pointer to root node's pointer:
*/
static int snapshot_tree_ptr_repair(struct btree_trans *trans,
struct btree_iter *iter,
struct bkey_s_c k,
struct bch_snapshot *s)
{
struct bch_fs *c = trans->c;
struct btree_iter root_iter;
struct bch_snapshot_tree s_t;
struct bkey_s_c_snapshot root;
struct bkey_i_snapshot *u;
u32 root_id = bch2_snapshot_root(c, k.k->p.offset), tree_id;
int ret;
root = bch2_bkey_get_iter_typed(trans, &root_iter,
BTREE_ID_snapshots, POS(0, root_id),
BTREE_ITER_with_updates, snapshot);
ret = bkey_err(root);
if (ret)
goto err;
tree_id = le32_to_cpu(root.v->tree);
ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);
if (ret && !bch2_err_matches(ret, ENOENT))
return ret;
if (ret || le32_to_cpu(s_t.root_snapshot) != root_id) {
u = bch2_bkey_make_mut_typed(trans, &root_iter, &root.s_c, 0, snapshot);
ret = PTR_ERR_OR_ZERO(u) ?:
bch2_snapshot_tree_create(trans, root_id,
bch2_snapshot_tree_oldest_subvol(c, root_id),
&tree_id);
if (ret)
goto err;
u->v.tree = cpu_to_le32(tree_id);
if (k.k->p.offset == root_id)
*s = u->v;
}
if (k.k->p.offset != root_id) {
u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
ret = PTR_ERR_OR_ZERO(u);
if (ret)
goto err;
u->v.tree = cpu_to_le32(tree_id);
*s = u->v;
}
err:
bch2_trans_iter_exit(trans, &root_iter);
return ret;
}
static int check_snapshot(struct btree_trans *trans,
struct btree_iter *iter,
struct bkey_s_c k)
{
struct bch_fs *c = trans->c;
struct bch_snapshot s;
struct bch_subvolume subvol;
struct bch_snapshot v;
struct bkey_i_snapshot *u;
u32 parent_id = bch2_snapshot_parent_early(c, k.k->p.offset);
u32 real_depth;
struct printbuf buf = PRINTBUF;
u32 i, id;
int ret = 0;
if (k.k->type != KEY_TYPE_snapshot)
return 0;
memset(&s, 0, sizeof(s));
memcpy(&s, k.v, min(sizeof(s), bkey_val_bytes(k.k)));
id = le32_to_cpu(s.parent);
if (id) {
ret = bch2_snapshot_lookup(trans, id, &v);
if (bch2_err_matches(ret, ENOENT))
bch_err(c, "snapshot with nonexistent parent:\n %s",
(bch2_bkey_val_to_text(&buf, c, k), buf.buf));
if (ret)
goto err;
if (le32_to_cpu(v.children[0]) != k.k->p.offset &&
le32_to_cpu(v.children[1]) != k.k->p.offset) {
bch_err(c, "snapshot parent %u missing pointer to child %llu",
id, k.k->p.offset);
ret = -EINVAL;
goto err;
}
}
for (i = 0; i < 2 && s.children[i]; i++) {
id = le32_to_cpu(s.children[i]);
ret = bch2_snapshot_lookup(trans, id, &v);
if (bch2_err_matches(ret, ENOENT))
bch_err(c, "snapshot node %llu has nonexistent child %u",
k.k->p.offset, id);
if (ret)
goto err;
if (le32_to_cpu(v.parent) != k.k->p.offset) {
bch_err(c, "snapshot child %u has wrong parent (got %u should be %llu)",
id, le32_to_cpu(v.parent), k.k->p.offset);
ret = -EINVAL;
goto err;
}
}
bool should_have_subvol = BCH_SNAPSHOT_SUBVOL(&s) &&
!BCH_SNAPSHOT_DELETED(&s);
if (should_have_subvol) {
id = le32_to_cpu(s.subvol);
ret = bch2_subvolume_get(trans, id, 0, false, &subvol);
if (bch2_err_matches(ret, ENOENT))
bch_err(c, "snapshot points to nonexistent subvolume:\n %s",
(bch2_bkey_val_to_text(&buf, c, k), buf.buf));
if (ret)
goto err;
if (BCH_SNAPSHOT_SUBVOL(&s) != (le32_to_cpu(subvol.snapshot) == k.k->p.offset)) {
bch_err(c, "snapshot node %llu has wrong BCH_SNAPSHOT_SUBVOL",
k.k->p.offset);
ret = -EINVAL;
goto err;
}
} else {
if (fsck_err_on(s.subvol,
trans, snapshot_should_not_have_subvol,
"snapshot should not point to subvol:\n %s",
(bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
ret = PTR_ERR_OR_ZERO(u);
if (ret)
goto err;
u->v.subvol = 0;
s = u->v;
}
}
ret = snapshot_tree_ptr_good(trans, k.k->p.offset, le32_to_cpu(s.tree));
if (ret < 0)
goto err;
if (fsck_err_on(!ret,
trans, snapshot_to_bad_snapshot_tree,
"snapshot points to missing/incorrect tree:\n %s",
(bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
ret = snapshot_tree_ptr_repair(trans, iter, k, &s);
if (ret)
goto err;
}
ret = 0;
real_depth = bch2_snapshot_depth(c, parent_id);
if (fsck_err_on(le32_to_cpu(s.depth) != real_depth,
trans, snapshot_bad_depth,
"snapshot with incorrect depth field, should be %u:\n %s",
real_depth, (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
ret = PTR_ERR_OR_ZERO(u);
if (ret)
goto err;
u->v.depth = cpu_to_le32(real_depth);
s = u->v;
}
ret = snapshot_skiplist_good(trans, k.k->p.offset, s);
if (ret < 0)
goto err;
if (fsck_err_on(!ret,
trans, snapshot_bad_skiplist,
"snapshot with bad skiplist field:\n %s",
(bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
ret = PTR_ERR_OR_ZERO(u);
if (ret)
goto err;
for (i = 0; i < ARRAY_SIZE(u->v.skip); i++)
u->v.skip[i] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent_id));
bubble_sort(u->v.skip, ARRAY_SIZE(u->v.skip), cmp_le32);
s = u->v;
}
ret = 0;
err:
fsck_err:
printbuf_exit(&buf);
return ret;
}
int bch2_check_snapshots(struct bch_fs *c)
{
/*
* We iterate backwards as checking/fixing the depth field requires that
* the parent's depth already be correct:
*/
int ret = bch2_trans_run(c,
for_each_btree_key_reverse_commit(trans, iter,
BTREE_ID_snapshots, POS_MAX,
BTREE_ITER_prefetch, k,
NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
check_snapshot(trans, &iter, k)));
bch_err_fn(c, ret);
return ret;
}
static int check_snapshot_exists(struct btree_trans *trans, u32 id)
{
struct bch_fs *c = trans->c;
if (bch2_snapshot_equiv(c, id))
return 0;
/* 0 is an invalid tree ID */
u32 tree_id = 0;
int ret = bch2_snapshot_tree_create(trans, id, 0, &tree_id);
if (ret)
return ret;
struct bkey_i_snapshot *snapshot = bch2_trans_kmalloc(trans, sizeof(*snapshot));
ret = PTR_ERR_OR_ZERO(snapshot);
if (ret)
return ret;
bkey_snapshot_init(&snapshot->k_i);
snapshot->k.p = POS(0, id);
snapshot->v.tree = cpu_to_le32(tree_id);
snapshot->v.btime.lo = cpu_to_le64(bch2_current_time(c));
return bch2_btree_insert_trans(trans, BTREE_ID_snapshots, &snapshot->k_i, 0) ?:
bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0,
bkey_s_c_null, bkey_i_to_s(&snapshot->k_i), 0) ?:
bch2_snapshot_set_equiv(trans, bkey_i_to_s_c(&snapshot->k_i));
}
/* Figure out which snapshot nodes belong in the same tree: */
struct snapshot_tree_reconstruct {
enum btree_id btree;
struct bpos cur_pos;
snapshot_id_list cur_ids;
DARRAY(snapshot_id_list) trees;
};
static void snapshot_tree_reconstruct_exit(struct snapshot_tree_reconstruct *r)
{
darray_for_each(r->trees, i)
darray_exit(i);
darray_exit(&r->trees);
darray_exit(&r->cur_ids);
}
static inline bool same_snapshot(struct snapshot_tree_reconstruct *r, struct bpos pos)
{
return r->btree == BTREE_ID_inodes
? r->cur_pos.offset == pos.offset
: r->cur_pos.inode == pos.inode;
}
static inline bool snapshot_id_lists_have_common(snapshot_id_list *l, snapshot_id_list *r)
{
darray_for_each(*l, i)
if (snapshot_list_has_id(r, *i))
return true;
return false;
}
static void snapshot_id_list_to_text(struct printbuf *out, snapshot_id_list *s)
{
bool first = true;
darray_for_each(*s, i) {
if (!first)
prt_char(out, ' ');
first = false;
prt_printf(out, "%u", *i);
}
}
static int snapshot_tree_reconstruct_next(struct bch_fs *c, struct snapshot_tree_reconstruct *r)
{
if (r->cur_ids.nr) {
darray_for_each(r->trees, i)
if (snapshot_id_lists_have_common(i, &r->cur_ids)) {
int ret = snapshot_list_merge(c, i, &r->cur_ids);
if (ret)
return ret;
goto out;
}
darray_push(&r->trees, r->cur_ids);
darray_init(&r->cur_ids);
}
out:
r->cur_ids.nr = 0;
return 0;
}
static int get_snapshot_trees(struct bch_fs *c, struct snapshot_tree_reconstruct *r, struct bpos pos)
{
if (!same_snapshot(r, pos))
snapshot_tree_reconstruct_next(c, r);
r->cur_pos = pos;
return snapshot_list_add_nodup(c, &r->cur_ids, pos.snapshot);
}
int bch2_reconstruct_snapshots(struct bch_fs *c)
{
struct btree_trans *trans = bch2_trans_get(c);
struct printbuf buf = PRINTBUF;
struct snapshot_tree_reconstruct r = {};
int ret = 0;
for (unsigned btree = 0; btree < BTREE_ID_NR; btree++) {
if (btree_type_has_snapshots(btree)) {
r.btree = btree;
ret = for_each_btree_key(trans, iter, btree, POS_MIN,
BTREE_ITER_all_snapshots|BTREE_ITER_prefetch, k, ({
get_snapshot_trees(c, &r, k.k->p);
}));
if (ret)
goto err;
snapshot_tree_reconstruct_next(c, &r);
}
}
darray_for_each(r.trees, t) {
printbuf_reset(&buf);
snapshot_id_list_to_text(&buf, t);
darray_for_each(*t, id) {
if (fsck_err_on(!bch2_snapshot_equiv(c, *id),
trans, snapshot_node_missing,
"snapshot node %u from tree %s missing, recreate?", *id, buf.buf)) {
if (t->nr > 1) {
bch_err(c, "cannot reconstruct snapshot trees with multiple nodes");
ret = -BCH_ERR_fsck_repair_unimplemented;
goto err;
}
ret = commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
check_snapshot_exists(trans, *id));
if (ret)
goto err;
}
}
}
fsck_err:
err:
bch2_trans_put(trans);
snapshot_tree_reconstruct_exit(&r);
printbuf_exit(&buf);
bch_err_fn(c, ret);
return ret;
}
int bch2_check_key_has_snapshot(struct btree_trans *trans,
struct btree_iter *iter,
struct bkey_s_c k)
{
struct bch_fs *c = trans->c;
struct printbuf buf = PRINTBUF;
int ret = 0;
if (fsck_err_on(!bch2_snapshot_equiv(c, k.k->p.snapshot),
trans, bkey_in_missing_snapshot,
"key in missing snapshot %s, delete?",
(bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
ret = bch2_btree_delete_at(trans, iter,
BTREE_UPDATE_internal_snapshot_node) ?: 1;
fsck_err:
printbuf_exit(&buf);
return ret;
}
/*
* Mark a snapshot as deleted, for future cleanup:
*/
int bch2_snapshot_node_set_deleted(struct btree_trans *trans, u32 id)
{
struct btree_iter iter;
struct bkey_i_snapshot *s;
int ret = 0;
s = bch2_bkey_get_mut_typed(trans, &iter,
BTREE_ID_snapshots, POS(0, id),
0, snapshot);
ret = PTR_ERR_OR_ZERO(s);
if (unlikely(ret)) {
bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT),
trans->c, "missing snapshot %u", id);
return ret;
}
/* already deleted? */
if (BCH_SNAPSHOT_DELETED(&s->v))
goto err;
SET_BCH_SNAPSHOT_DELETED(&s->v, true);
SET_BCH_SNAPSHOT_SUBVOL(&s->v, false);
s->v.subvol = 0;
err:
bch2_trans_iter_exit(trans, &iter);
return ret;
}
static inline void normalize_snapshot_child_pointers(struct bch_snapshot *s)
{
if (le32_to_cpu(s->children[0]) < le32_to_cpu(s->children[1]))
swap(s->children[0], s->children[1]);
}
static int bch2_snapshot_node_delete(struct btree_trans *trans, u32 id)
{
struct bch_fs *c = trans->c;
struct btree_iter iter, p_iter = (struct btree_iter) { NULL };
struct btree_iter c_iter = (struct btree_iter) { NULL };
struct btree_iter tree_iter = (struct btree_iter) { NULL };
struct bkey_s_c_snapshot s;
u32 parent_id, child_id;
unsigned i;
int ret = 0;
s = bch2_bkey_get_iter_typed(trans, &iter, BTREE_ID_snapshots, POS(0, id),
BTREE_ITER_intent, snapshot);
ret = bkey_err(s);
bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
"missing snapshot %u", id);
if (ret)
goto err;
BUG_ON(s.v->children[1]);
parent_id = le32_to_cpu(s.v->parent);
child_id = le32_to_cpu(s.v->children[0]);
if (parent_id) {
struct bkey_i_snapshot *parent;
parent = bch2_bkey_get_mut_typed(trans, &p_iter,
BTREE_ID_snapshots, POS(0, parent_id),
0, snapshot);
ret = PTR_ERR_OR_ZERO(parent);
bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
"missing snapshot %u", parent_id);
if (unlikely(ret))
goto err;
/* find entry in parent->children for node being deleted */
for (i = 0; i < 2; i++)
if (le32_to_cpu(parent->v.children[i]) == id)
break;
if (bch2_fs_inconsistent_on(i == 2, c,
"snapshot %u missing child pointer to %u",
parent_id, id))
goto err;
parent->v.children[i] = cpu_to_le32(child_id);
normalize_snapshot_child_pointers(&parent->v);
}
if (child_id) {
struct bkey_i_snapshot *child;
child = bch2_bkey_get_mut_typed(trans, &c_iter,
BTREE_ID_snapshots, POS(0, child_id),
0, snapshot);
ret = PTR_ERR_OR_ZERO(child);
bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
"missing snapshot %u", child_id);
if (unlikely(ret))
goto err;
child->v.parent = cpu_to_le32(parent_id);
if (!child->v.parent) {
child->v.skip[0] = 0;
child->v.skip[1] = 0;
child->v.skip[2] = 0;
}
}
if (!parent_id) {
/*
* We're deleting the root of a snapshot tree: update the
* snapshot_tree entry to point to the new root, or delete it if
* this is the last snapshot ID in this tree:
*/
struct bkey_i_snapshot_tree *s_t;
BUG_ON(s.v->children[1]);
s_t = bch2_bkey_get_mut_typed(trans, &tree_iter,
BTREE_ID_snapshot_trees, POS(0, le32_to_cpu(s.v->tree)),
0, snapshot_tree);
ret = PTR_ERR_OR_ZERO(s_t);
if (ret)
goto err;
if (s.v->children[0]) {
s_t->v.root_snapshot = s.v->children[0];
} else {
s_t->k.type = KEY_TYPE_deleted;
set_bkey_val_u64s(&s_t->k, 0);
}
}
ret = bch2_btree_delete_at(trans, &iter, 0);
err:
bch2_trans_iter_exit(trans, &tree_iter);
bch2_trans_iter_exit(trans, &p_iter);
bch2_trans_iter_exit(trans, &c_iter);
bch2_trans_iter_exit(trans, &iter);
return ret;
}
static int create_snapids(struct btree_trans *trans, u32 parent, u32 tree,
u32 *new_snapids,
u32 *snapshot_subvols,
unsigned nr_snapids)
{
struct bch_fs *c = trans->c;
struct btree_iter iter;
struct bkey_i_snapshot *n;
struct bkey_s_c k;
unsigned i, j;
u32 depth = bch2_snapshot_depth(c, parent);
int ret;
bch2_trans_iter_init(trans, &iter, BTREE_ID_snapshots,
POS_MIN, BTREE_ITER_intent);
k = bch2_btree_iter_peek(&iter);
ret = bkey_err(k);
if (ret)
goto err;
for (i = 0; i < nr_snapids; i++) {
k = bch2_btree_iter_prev_slot(&iter);
ret = bkey_err(k);
if (ret)
goto err;
if (!k.k || !k.k->p.offset) {
ret = -BCH_ERR_ENOSPC_snapshot_create;
goto err;
}
n = bch2_bkey_alloc(trans, &iter, 0, snapshot);
ret = PTR_ERR_OR_ZERO(n);
if (ret)
goto err;
n->v.flags = 0;
n->v.parent = cpu_to_le32(parent);
n->v.subvol = cpu_to_le32(snapshot_subvols[i]);
n->v.tree = cpu_to_le32(tree);
n->v.depth = cpu_to_le32(depth);
n->v.btime.lo = cpu_to_le64(bch2_current_time(c));
n->v.btime.hi = 0;
for (j = 0; j < ARRAY_SIZE(n->v.skip); j++)
n->v.skip[j] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent));
bubble_sort(n->v.skip, ARRAY_SIZE(n->v.skip), cmp_le32);
SET_BCH_SNAPSHOT_SUBVOL(&n->v, true);
ret = __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0,
bkey_s_c_null, bkey_i_to_s_c(&n->k_i), 0);
if (ret)
goto err;
new_snapids[i] = iter.pos.offset;
mutex_lock(&c->snapshot_table_lock);
snapshot_t_mut(c, new_snapids[i])->equiv = new_snapids[i];
mutex_unlock(&c->snapshot_table_lock);
}
err:
bch2_trans_iter_exit(trans, &iter);
return ret;
}
/*
* Create new snapshot IDs as children of an existing snapshot ID:
*/
static int bch2_snapshot_node_create_children(struct btree_trans *trans, u32 parent,
u32 *new_snapids,
u32 *snapshot_subvols,
unsigned nr_snapids)
{
struct btree_iter iter;
struct bkey_i_snapshot *n_parent;
int ret = 0;
n_parent = bch2_bkey_get_mut_typed(trans, &iter,
BTREE_ID_snapshots, POS(0, parent),
0, snapshot);
ret = PTR_ERR_OR_ZERO(n_parent);
if (unlikely(ret)) {
if (bch2_err_matches(ret, ENOENT))
bch_err(trans->c, "snapshot %u not found", parent);
return ret;
}
if (n_parent->v.children[0] || n_parent->v.children[1]) {
bch_err(trans->c, "Trying to add child snapshot nodes to parent that already has children");
ret = -EINVAL;
goto err;
}
ret = create_snapids(trans, parent, le32_to_cpu(n_parent->v.tree),
new_snapids, snapshot_subvols, nr_snapids);
if (ret)
goto err;
n_parent->v.children[0] = cpu_to_le32(new_snapids[0]);
n_parent->v.children[1] = cpu_to_le32(new_snapids[1]);
n_parent->v.subvol = 0;
SET_BCH_SNAPSHOT_SUBVOL(&n_parent->v, false);
err:
bch2_trans_iter_exit(trans, &iter);
return ret;
}
/*
* Create a snapshot node that is the root of a new tree:
*/
static int bch2_snapshot_node_create_tree(struct btree_trans *trans,
u32 *new_snapids,
u32 *snapshot_subvols,
unsigned nr_snapids)
{
struct bkey_i_snapshot_tree *n_tree;
int ret;
n_tree = __bch2_snapshot_tree_create(trans);
ret = PTR_ERR_OR_ZERO(n_tree) ?:
create_snapids(trans, 0, n_tree->k.p.offset,
new_snapids, snapshot_subvols, nr_snapids);
if (ret)
return ret;
n_tree->v.master_subvol = cpu_to_le32(snapshot_subvols[0]);
n_tree->v.root_snapshot = cpu_to_le32(new_snapids[0]);
return 0;
}
int bch2_snapshot_node_create(struct btree_trans *trans, u32 parent,
u32 *new_snapids,
u32 *snapshot_subvols,
unsigned nr_snapids)
{
BUG_ON((parent == 0) != (nr_snapids == 1));
BUG_ON((parent != 0) != (nr_snapids == 2));
return parent
? bch2_snapshot_node_create_children(trans, parent,
new_snapids, snapshot_subvols, nr_snapids)
: bch2_snapshot_node_create_tree(trans,
new_snapids, snapshot_subvols, nr_snapids);
}
/*
* If we have an unlinked inode in an internal snapshot node, and the inode
* really has been deleted in all child snapshots, how does this get cleaned up?
*
* first there is the problem of how keys that have been overwritten in all
* child snapshots get deleted (unimplemented?), but inodes may perhaps be
* special?
*
* also: unlinked inode in internal snapshot appears to not be getting deleted
* correctly if inode doesn't exist in leaf snapshots
*
* solution:
*
* for a key in an interior snapshot node that needs work to be done that
* requires it to be mutated: iterate over all descendent leaf nodes and copy
* that key to snapshot leaf nodes, where we can mutate it
*/
static int delete_dead_snapshots_process_key(struct btree_trans *trans,
struct btree_iter *iter,
struct bkey_s_c k,
snapshot_id_list *deleted,
snapshot_id_list *equiv_seen,
struct bpos *last_pos)
{
int ret = bch2_check_key_has_snapshot(trans, iter, k);
if (ret)
return ret < 0 ? ret : 0;
struct bch_fs *c = trans->c;
u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot);
if (!equiv) /* key for invalid snapshot node, but we chose not to delete */
return 0;
if (!bkey_eq(k.k->p, *last_pos))
equiv_seen->nr = 0;
if (snapshot_list_has_id(deleted, k.k->p.snapshot))
return bch2_btree_delete_at(trans, iter,
BTREE_UPDATE_internal_snapshot_node);
if (!bpos_eq(*last_pos, k.k->p) &&
snapshot_list_has_id(equiv_seen, equiv))
return bch2_btree_delete_at(trans, iter,
BTREE_UPDATE_internal_snapshot_node);
*last_pos = k.k->p;
ret = snapshot_list_add_nodup(c, equiv_seen, equiv);
if (ret)
return ret;
/*
* When we have a linear chain of snapshot nodes, we consider
* those to form an equivalence class: we're going to collapse
* them all down to a single node, and keep the leaf-most node -
* which has the same id as the equivalence class id.
*
* If there are multiple keys in different snapshots at the same
* position, we're only going to keep the one in the newest
* snapshot (we delete the others above) - the rest have been
* overwritten and are redundant, and for the key we're going to keep we
* need to move it to the equivalance class ID if it's not there
* already.
*/
if (equiv != k.k->p.snapshot) {
struct bkey_i *new = bch2_bkey_make_mut_noupdate(trans, k);
int ret = PTR_ERR_OR_ZERO(new);
if (ret)
return ret;
new->k.p.snapshot = equiv;
struct btree_iter new_iter;
bch2_trans_iter_init(trans, &new_iter, iter->btree_id, new->k.p,
BTREE_ITER_all_snapshots|
BTREE_ITER_cached|
BTREE_ITER_intent);
ret = bch2_btree_iter_traverse(&new_iter) ?:
bch2_trans_update(trans, &new_iter, new,
BTREE_UPDATE_internal_snapshot_node) ?:
bch2_btree_delete_at(trans, iter,
BTREE_UPDATE_internal_snapshot_node);
bch2_trans_iter_exit(trans, &new_iter);
if (ret)
return ret;
}
return 0;
}
static int bch2_snapshot_needs_delete(struct btree_trans *trans, struct bkey_s_c k)
{
struct bkey_s_c_snapshot snap;
u32 children[2];
int ret;
if (k.k->type != KEY_TYPE_snapshot)
return 0;
snap = bkey_s_c_to_snapshot(k);
if (BCH_SNAPSHOT_DELETED(snap.v) ||
BCH_SNAPSHOT_SUBVOL(snap.v))
return 0;
children[0] = le32_to_cpu(snap.v->children[0]);
children[1] = le32_to_cpu(snap.v->children[1]);
ret = bch2_snapshot_live(trans, children[0]) ?:
bch2_snapshot_live(trans, children[1]);
if (ret < 0)
return ret;
return !ret;
}
/*
* For a given snapshot, if it doesn't have a subvolume that points to it, and
* it doesn't have child snapshot nodes - it's now redundant and we can mark it
* as deleted.
*/
static int bch2_delete_redundant_snapshot(struct btree_trans *trans, struct bkey_s_c k)
{
int ret = bch2_snapshot_needs_delete(trans, k);
return ret <= 0
? ret
: bch2_snapshot_node_set_deleted(trans, k.k->p.offset);
}
static inline u32 bch2_snapshot_nth_parent_skip(struct bch_fs *c, u32 id, u32 n,
snapshot_id_list *skip)
{
rcu_read_lock();
while (snapshot_list_has_id(skip, id))
id = __bch2_snapshot_parent(c, id);
while (n--) {
do {
id = __bch2_snapshot_parent(c, id);
} while (snapshot_list_has_id(skip, id));
}
rcu_read_unlock();
return id;
}
static int bch2_fix_child_of_deleted_snapshot(struct btree_trans *trans,
struct btree_iter *iter, struct bkey_s_c k,
snapshot_id_list *deleted)
{
struct bch_fs *c = trans->c;
u32 nr_deleted_ancestors = 0;
struct bkey_i_snapshot *s;
int ret;
if (k.k->type != KEY_TYPE_snapshot)
return 0;
if (snapshot_list_has_id(deleted, k.k->p.offset))
return 0;
s = bch2_bkey_make_mut_noupdate_typed(trans, k, snapshot);
ret = PTR_ERR_OR_ZERO(s);
if (ret)
return ret;
darray_for_each(*deleted, i)
nr_deleted_ancestors += bch2_snapshot_is_ancestor(c, s->k.p.offset, *i);
if (!nr_deleted_ancestors)
return 0;
le32_add_cpu(&s->v.depth, -nr_deleted_ancestors);
if (!s->v.depth) {
s->v.skip[0] = 0;
s->v.skip[1] = 0;
s->v.skip[2] = 0;
} else {
u32 depth = le32_to_cpu(s->v.depth);
u32 parent = bch2_snapshot_parent(c, s->k.p.offset);
for (unsigned j = 0; j < ARRAY_SIZE(s->v.skip); j++) {
u32 id = le32_to_cpu(s->v.skip[j]);
if (snapshot_list_has_id(deleted, id)) {
id = bch2_snapshot_nth_parent_skip(c,
parent,
depth > 1
? get_random_u32_below(depth - 1)
: 0,
deleted);
s->v.skip[j] = cpu_to_le32(id);
}
}
bubble_sort(s->v.skip, ARRAY_SIZE(s->v.skip), cmp_le32);
}
return bch2_trans_update(trans, iter, &s->k_i, 0);
}
int bch2_delete_dead_snapshots(struct bch_fs *c)
{
struct btree_trans *trans;
snapshot_id_list deleted = { 0 };
snapshot_id_list deleted_interior = { 0 };
int ret = 0;
if (!test_and_clear_bit(BCH_FS_need_delete_dead_snapshots, &c->flags))
return 0;
trans = bch2_trans_get(c);
/*
* For every snapshot node: If we have no live children and it's not
* pointed to by a subvolume, delete it:
*/
ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots,
POS_MIN, 0, k,
NULL, NULL, 0,
bch2_delete_redundant_snapshot(trans, k));
bch_err_msg(c, ret, "deleting redundant snapshots");
if (ret)
goto err;
ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,
POS_MIN, 0, k,
bch2_snapshot_set_equiv(trans, k));
bch_err_msg(c, ret, "in bch2_snapshots_set_equiv");
if (ret)
goto err;
ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,
POS_MIN, 0, k, ({
if (k.k->type != KEY_TYPE_snapshot)
continue;
BCH_SNAPSHOT_DELETED(bkey_s_c_to_snapshot(k).v)
? snapshot_list_add(c, &deleted, k.k->p.offset)
: 0;
}));
bch_err_msg(c, ret, "walking snapshots");
if (ret)
goto err;
for (unsigned btree = 0; btree < BTREE_ID_NR; btree++) {
struct bpos last_pos = POS_MIN;
snapshot_id_list equiv_seen = { 0 };
struct disk_reservation res = { 0 };
if (!btree_type_has_snapshots(btree))
continue;
ret = for_each_btree_key_commit(trans, iter,
btree, POS_MIN,
BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k,
&res, NULL, BCH_TRANS_COMMIT_no_enospc,
delete_dead_snapshots_process_key(trans, &iter, k, &deleted,
&equiv_seen, &last_pos));
bch2_disk_reservation_put(c, &res);
darray_exit(&equiv_seen);
bch_err_msg(c, ret, "deleting keys from dying snapshots");
if (ret)
goto err;
}
bch2_trans_unlock(trans);
down_write(&c->snapshot_create_lock);
ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,
POS_MIN, 0, k, ({
u32 snapshot = k.k->p.offset;
u32 equiv = bch2_snapshot_equiv(c, snapshot);
equiv != snapshot
? snapshot_list_add(c, &deleted_interior, snapshot)
: 0;
}));
bch_err_msg(c, ret, "walking snapshots");
if (ret)
goto err_create_lock;
/*
* Fixing children of deleted snapshots can't be done completely
* atomically, if we crash between here and when we delete the interior
* nodes some depth fields will be off:
*/
ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots, POS_MIN,
BTREE_ITER_intent, k,
NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
bch2_fix_child_of_deleted_snapshot(trans, &iter, k, &deleted_interior));
if (ret)
goto err_create_lock;
darray_for_each(deleted, i) {
ret = commit_do(trans, NULL, NULL, 0,
bch2_snapshot_node_delete(trans, *i));
bch_err_msg(c, ret, "deleting snapshot %u", *i);
if (ret)
goto err_create_lock;
}
darray_for_each(deleted_interior, i) {
ret = commit_do(trans, NULL, NULL, 0,
bch2_snapshot_node_delete(trans, *i));
bch_err_msg(c, ret, "deleting snapshot %u", *i);
if (ret)
goto err_create_lock;
}
err_create_lock:
up_write(&c->snapshot_create_lock);
err:
darray_exit(&deleted_interior);
darray_exit(&deleted);
bch2_trans_put(trans);
bch_err_fn(c, ret);
return ret;
}
void bch2_delete_dead_snapshots_work(struct work_struct *work)
{
struct bch_fs *c = container_of(work, struct bch_fs, snapshot_delete_work);
set_worker_desc("bcachefs-delete-dead-snapshots/%s", c->name);
bch2_delete_dead_snapshots(c);
bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots);
}
void bch2_delete_dead_snapshots_async(struct bch_fs *c)
{
if (bch2_write_ref_tryget(c, BCH_WRITE_REF_delete_dead_snapshots) &&
!queue_work(c->write_ref_wq, &c->snapshot_delete_work))
bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots);
}
int __bch2_key_has_snapshot_overwrites(struct btree_trans *trans,
enum btree_id id,
struct bpos pos)
{
struct bch_fs *c = trans->c;
struct btree_iter iter;
struct bkey_s_c k;
int ret;
bch2_trans_iter_init(trans, &iter, id, pos,
BTREE_ITER_not_extents|
BTREE_ITER_all_snapshots);
while (1) {
k = bch2_btree_iter_prev(&iter);
ret = bkey_err(k);
if (ret)
break;
if (!k.k)
break;
if (!bkey_eq(pos, k.k->p))
break;
if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, pos.snapshot)) {
ret = 1;
break;
}
}
bch2_trans_iter_exit(trans, &iter);
return ret;
}
static u32 bch2_snapshot_smallest_child(struct bch_fs *c, u32 id)
{
const struct snapshot_t *s = snapshot_t(c, id);
return s->children[1] ?: s->children[0];
}
static u32 bch2_snapshot_smallest_descendent(struct bch_fs *c, u32 id)
{
u32 child;
while ((child = bch2_snapshot_smallest_child(c, id)))
id = child;
return id;
}
static int bch2_propagate_key_to_snapshot_leaf(struct btree_trans *trans,
enum btree_id btree,
struct bkey_s_c interior_k,
u32 leaf_id, struct bpos *new_min_pos)
{
struct btree_iter iter;
struct bpos pos = interior_k.k->p;
struct bkey_s_c k;
struct bkey_i *new;
int ret;
pos.snapshot = leaf_id;
bch2_trans_iter_init(trans, &iter, btree, pos, BTREE_ITER_intent);
k = bch2_btree_iter_peek_slot(&iter);
ret = bkey_err(k);
if (ret)
goto out;
/* key already overwritten in this snapshot? */
if (k.k->p.snapshot != interior_k.k->p.snapshot)
goto out;
if (bpos_eq(*new_min_pos, POS_MIN)) {
*new_min_pos = k.k->p;
new_min_pos->snapshot = leaf_id;
}
new = bch2_bkey_make_mut_noupdate(trans, interior_k);
ret = PTR_ERR_OR_ZERO(new);
if (ret)
goto out;
new->k.p.snapshot = leaf_id;
ret = bch2_trans_update(trans, &iter, new, 0);
out:
bch2_set_btree_iter_dontneed(&iter);
bch2_trans_iter_exit(trans, &iter);
return ret;
}
int bch2_propagate_key_to_snapshot_leaves(struct btree_trans *trans,
enum btree_id btree,
struct bkey_s_c k,
struct bpos *new_min_pos)
{
struct bch_fs *c = trans->c;
struct bkey_buf sk;
u32 restart_count = trans->restart_count;
int ret = 0;
bch2_bkey_buf_init(&sk);
bch2_bkey_buf_reassemble(&sk, c, k);
k = bkey_i_to_s_c(sk.k);
*new_min_pos = POS_MIN;
for (u32 id = bch2_snapshot_smallest_descendent(c, k.k->p.snapshot);
id < k.k->p.snapshot;
id++) {
if (!bch2_snapshot_is_ancestor(c, id, k.k->p.snapshot) ||
!bch2_snapshot_is_leaf(c, id))
continue;
again:
ret = btree_trans_too_many_iters(trans) ?:
bch2_propagate_key_to_snapshot_leaf(trans, btree, k, id, new_min_pos) ?:
bch2_trans_commit(trans, NULL, NULL, 0);
if (ret && bch2_err_matches(ret, BCH_ERR_transaction_restart)) {
bch2_trans_begin(trans);
goto again;
}
if (ret)
break;
}
bch2_bkey_buf_exit(&sk, c);
return ret ?: trans_was_restarted(trans, restart_count);
}
static int bch2_check_snapshot_needs_deletion(struct btree_trans *trans, struct bkey_s_c k)
{
struct bch_fs *c = trans->c;
struct bkey_s_c_snapshot snap;
int ret = 0;
if (k.k->type != KEY_TYPE_snapshot)
return 0;
snap = bkey_s_c_to_snapshot(k);
if (BCH_SNAPSHOT_DELETED(snap.v) ||
bch2_snapshot_equiv(c, k.k->p.offset) != k.k->p.offset ||
(ret = bch2_snapshot_needs_delete(trans, k)) > 0) {
set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags);
return 0;
}
return ret;
}
int bch2_snapshots_read(struct bch_fs *c)
{
int ret = bch2_trans_run(c,
for_each_btree_key(trans, iter, BTREE_ID_snapshots,
POS_MIN, 0, k,
__bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, bkey_s_c_null, k, 0) ?:
bch2_snapshot_set_equiv(trans, k) ?:
bch2_check_snapshot_needs_deletion(trans, k)) ?:
for_each_btree_key(trans, iter, BTREE_ID_snapshots,
POS_MIN, 0, k,
(set_is_ancestor_bitmap(c, k.k->p.offset), 0)));
bch_err_fn(c, ret);
/*
* It's important that we check if we need to reconstruct snapshots
* before going RW, so we mark that pass as required in the superblock -
* otherwise, we could end up deleting keys with missing snapshot nodes
* instead
*/
BUG_ON(!test_bit(BCH_FS_new_fs, &c->flags) &&
test_bit(BCH_FS_may_go_rw, &c->flags));
if (bch2_err_matches(ret, EIO) ||
(c->sb.btrees_lost_data & BIT_ULL(BTREE_ID_snapshots)))
ret = bch2_run_explicit_recovery_pass_persistent(c, BCH_RECOVERY_PASS_reconstruct_snapshots);
return ret;
}
void bch2_fs_snapshots_exit(struct bch_fs *c)
{
kvfree(rcu_dereference_protected(c->snapshots, true));
}
Codebase Browser
linux