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bcachefs: Handle race between stripe reuse, invalidate_stripe_to_dev

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When creating a new stripe, we may reuse an existing stripe that has
some empty and some nonempty blocks.

Generally, the existing stripe won't change underneath us - except for
block sector counts, which we copy to the new key in
ec_stripe_key_update.

But the device removal path can now invalidate stripe pointers to a
device, and that can race with stripe reuse.

Change ec_stripe_key_update() to check for and resolve this
inconsistency.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2024-10-13 19:38:00 -04:00
parent b1e562265e
commit cb6055e66f
2 changed files with 55 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

73
fs/bcachefs/ec.c
View File

@ -1206,47 +1206,62 @@ void bch2_do_stripe_deletes(struct bch_fs *c)
/* stripe creation: */
static int ec_stripe_key_update(struct btree_trans *trans,
struct bkey_i_stripe *new,
bool create)
struct bkey_i_stripe *old,
struct bkey_i_stripe *new)
{
struct bch_fs *c = trans->c;
struct btree_iter iter;
struct bkey_s_c k;
int ret;
bool create = !old;
k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_stripes,
new->k.p, BTREE_ITER_intent);
ret = bkey_err(k);
struct btree_iter iter;
struct bkey_s_c k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_stripes,
new->k.p, BTREE_ITER_intent);
int ret = bkey_err(k);
if (ret)
goto err;
if (k.k->type != (create ? KEY_TYPE_deleted : KEY_TYPE_stripe)) {
bch2_fs_inconsistent(c, "error %s stripe: got existing key type %s",
create ? "creating" : "updating",
bch2_bkey_types[k.k->type]);
if (bch2_fs_inconsistent_on(k.k->type != (create ? KEY_TYPE_deleted : KEY_TYPE_stripe),
c, "error %s stripe: got existing key type %s",
create ? "creating" : "updating",
bch2_bkey_types[k.k->type])) {
ret = -EINVAL;
goto err;
}
if (k.k->type == KEY_TYPE_stripe) {
const struct bch_stripe *old = bkey_s_c_to_stripe(k).v;
unsigned i;
const struct bch_stripe *v = bkey_s_c_to_stripe(k).v;
if (old->nr_blocks != new->v.nr_blocks) {
bch_err(c, "error updating stripe: nr_blocks does not match");
ret = -EINVAL;
goto err;
}
BUG_ON(old->v.nr_blocks != new->v.nr_blocks);
BUG_ON(old->v.nr_blocks != v->nr_blocks);
for (i = 0; i < new->v.nr_blocks; i++) {
unsigned v = stripe_blockcount_get(old, i);
for (unsigned i = 0; i < new->v.nr_blocks; i++) {
unsigned sectors = stripe_blockcount_get(v, i);
BUG_ON(v &&
(old->ptrs[i].dev != new->v.ptrs[i].dev ||
old->ptrs[i].gen != new->v.ptrs[i].gen ||
old->ptrs[i].offset != new->v.ptrs[i].offset));
if (!bch2_extent_ptr_eq(old->v.ptrs[i], new->v.ptrs[i]) && sectors) {
struct printbuf buf = PRINTBUF;
stripe_blockcount_set(&new->v, i, v);
prt_printf(&buf, "stripe changed nonempty block %u", i);
prt_str(&buf, "\nold: ");
bch2_bkey_val_to_text(&buf, c, k);
prt_str(&buf, "\nnew: ");
bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&new->k_i));
bch2_fs_inconsistent(c, "%s", buf.buf);
printbuf_exit(&buf);
ret = -EINVAL;
goto err;
}
/*
* If the stripe ptr changed underneath us, it must have
* been dev_remove_stripes() -> * invalidate_stripe_to_dev()
*/
if (!bch2_extent_ptr_eq(old->v.ptrs[i], v->ptrs[i])) {
BUG_ON(v->ptrs[i].dev != BCH_SB_MEMBER_INVALID);
if (bch2_extent_ptr_eq(old->v.ptrs[i], new->v.ptrs[i]))
new->v.ptrs[i].dev = BCH_SB_MEMBER_INVALID;
}
stripe_blockcount_set(&new->v, i, sectors);
}
}
@ -1508,8 +1523,10 @@ static void ec_stripe_create(struct ec_stripe_new *s)
BCH_TRANS_COMMIT_no_check_rw|
BCH_TRANS_COMMIT_no_enospc,
ec_stripe_key_update(trans,
bkey_i_to_stripe(&s->new_stripe.key),
!s->have_existing_stripe));
s->have_existing_stripe
? bkey_i_to_stripe(&s->existing_stripe.key)
: NULL,
bkey_i_to_stripe(&s->new_stripe.key)));
bch_err_msg(c, ret, "creating stripe key");
if (ret) {
goto err;

10
fs/bcachefs/extents.h
View File

@ -695,6 +695,16 @@ void bch2_bkey_ptrs_to_text(struct printbuf *, struct bch_fs *,
int bch2_bkey_ptrs_validate(struct bch_fs *, struct bkey_s_c,
enum bch_validate_flags);
static inline bool bch2_extent_ptr_eq(struct bch_extent_ptr ptr1,
struct bch_extent_ptr ptr2)
{
return (ptr1.cached == ptr2.cached &&
ptr1.unwritten == ptr2.unwritten &&
ptr1.offset == ptr2.offset &&
ptr1.dev == ptr2.dev &&
ptr1.dev == ptr2.dev);
}
void bch2_ptr_swab(struct bkey_s);
const struct bch_extent_rebalance *bch2_bkey_rebalance_opts(struct bkey_s_c);