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bcachefs: Simplify, fix bch2_backpointer_get_key()

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- backpointer_not_found() checks backpointers_no_use_write_buffer, no
   need to do it inbackpointer_get_key().

 - always use backpointer_get_node() for pointers to nodes:
   backpointer_get_key() was sometimes returning the key from the root
   node unlocked.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-11-04 20:22:56 -04:00
parent daba90f2da
commit 853960d00b
1 changed files with 34 additions and 45 deletions
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79
fs/bcachefs/backpointers.c
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@ -5,6 +5,7 @@
#include "backpointers.h"
#include "btree_cache.h"
#include "btree_update.h"
#include "btree_update_interior.h"
#include "btree_write_buffer.h"
#include "error.h"
@ -226,6 +227,11 @@ static void backpointer_not_found(struct btree_trans *trans,
struct printbuf buf = PRINTBUF;
struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
/*
* If we're using the btree write buffer, the backpointer we were
* looking at may have already been deleted - failure to find what it
* pointed to is not an error:
*/
if (likely(!bch2_backpointers_no_use_write_buffer))
return;
@ -256,56 +262,37 @@ struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
struct bch_backpointer bp,
unsigned iter_flags)
{
struct bch_fs *c = trans->c;
struct btree_root *r = bch2_btree_id_root(c, bp.btree_id);
struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
struct bkey_s_c k;
bch2_trans_node_iter_init(trans, iter,
bp.btree_id,
bp.pos,
0,
min(bp.level, r->level),
iter_flags);
k = bch2_btree_iter_peek_slot(iter);
if (bkey_err(k)) {
bch2_trans_iter_exit(trans, iter);
return k;
}
if (bp.level == r->level + 1)
k = bkey_i_to_s_c(&r->key);
if (k.k && extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))
return k;
bch2_trans_iter_exit(trans, iter);
if (unlikely(bch2_backpointers_no_use_write_buffer)) {
if (bp.level) {
struct btree *b;
/*
* If a backpointer for a btree node wasn't found, it may be
* because it was overwritten by a new btree node that hasn't
* been written out yet - backpointer_get_node() checks for
* this:
*/
b = bch2_backpointer_get_node(trans, iter, bp_pos, bp);
if (!IS_ERR_OR_NULL(b))
return bkey_i_to_s_c(&b->key);
if (likely(!bp.level)) {
struct bch_fs *c = trans->c;
struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
struct bkey_s_c k;
bch2_trans_node_iter_init(trans, iter,
bp.btree_id,
bp.pos,
0, 0,
iter_flags);
k = bch2_btree_iter_peek_slot(iter);
if (bkey_err(k)) {
bch2_trans_iter_exit(trans, iter);
if (IS_ERR(b))
return bkey_s_c_err(PTR_ERR(b));
return bkey_s_c_null;
return k;
}
backpointer_not_found(trans, bp_pos, bp, k);
}
if (k.k && extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))
return k;
return bkey_s_c_null;
bch2_trans_iter_exit(trans, iter);
backpointer_not_found(trans, bp_pos, bp, k);
return bkey_s_c_null;
} else {
struct btree *b = bch2_backpointer_get_node(trans, iter, bp_pos, bp);
if (IS_ERR_OR_NULL(b)) {
bch2_trans_iter_exit(trans, iter);
return IS_ERR(b) ? bkey_s_c_err(PTR_ERR(b)) : bkey_s_c_null;
}
return bkey_i_to_s_c(&b->key);
}
}
struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
@ -329,6 +316,8 @@ struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
if (IS_ERR(b))
goto err;
BUG_ON(b->c.level != bp.level - 1);
if (b && extent_matches_bp(c, bp.btree_id, bp.level,
bkey_i_to_s_c(&b->key),
bucket, bp))