unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
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bcachefs: dirent_points_to_inode() now warns on mismatch

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if an inode backpointer points to a dirent that doesn't point back,
that's an error we should warn about.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2024-09-23 22:22:00 -04:00
parent e057a290ef
commit a6508079b1
1 changed files with 56 additions and 28 deletions
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84
fs/bcachefs/fsck.c
View file

@ -21,6 +21,49 @@
#include <linux/bsearch.h>
#include <linux/dcache.h> /* struct qstr */
static bool inode_points_to_dirent(struct bch_inode_unpacked *inode,
struct bkey_s_c_dirent d)
{
return inode->bi_dir == d.k->p.inode &&
inode->bi_dir_offset == d.k->p.offset;
}
static bool dirent_points_to_inode_nowarn(struct bkey_s_c_dirent d,
struct bch_inode_unpacked *inode)
{
if (d.v->d_type == DT_SUBVOL
? le32_to_cpu(d.v->d_child_subvol) == inode->bi_subvol
: le64_to_cpu(d.v->d_inum) == inode->bi_inum)
return 0;
return -BCH_ERR_ENOENT_dirent_doesnt_match_inode;
}
static void dirent_inode_mismatch_msg(struct printbuf *out,
struct bch_fs *c,
struct bkey_s_c_dirent dirent,
struct bch_inode_unpacked *inode)
{
prt_str(out, "inode points to dirent that does not point back:");
prt_newline(out);
bch2_bkey_val_to_text(out, c, dirent.s_c);
prt_newline(out);
bch2_inode_unpacked_to_text(out, inode);
}
static int dirent_points_to_inode(struct bch_fs *c,
struct bkey_s_c_dirent dirent,
struct bch_inode_unpacked *inode)
{
int ret = dirent_points_to_inode_nowarn(dirent, inode);
if (ret) {
struct printbuf buf = PRINTBUF;
dirent_inode_mismatch_msg(&buf, c, dirent, inode);
bch_warn(c, "%s", buf.buf);
printbuf_exit(&buf);
}
return ret;
}
/*
* XXX: this is handling transaction restarts without returning
* -BCH_ERR_transaction_restart_nested, this is not how we do things anymore:
@ -371,7 +414,8 @@ static int reattach_subvol(struct btree_trans *trans, struct bkey_s_c_subvolume
return ret;
ret = remove_backpointer(trans, &inode);
bch_err_msg(c, ret, "removing dirent");
if (!bch2_err_matches(ret, ENOENT))
bch_err_msg(c, ret, "removing dirent");
if (ret)
return ret;
@ -900,21 +944,6 @@ static struct bkey_s_c_dirent inode_get_dirent(struct btree_trans *trans,
return dirent_get_by_pos(trans, iter, SPOS(inode->bi_dir, inode->bi_dir_offset, *snapshot));
}
static bool inode_points_to_dirent(struct bch_inode_unpacked *inode,
struct bkey_s_c_dirent d)
{
return inode->bi_dir == d.k->p.inode &&
inode->bi_dir_offset == d.k->p.offset;
}
static bool dirent_points_to_inode(struct bkey_s_c_dirent d,
struct bch_inode_unpacked *inode)
{
return d.v->d_type == DT_SUBVOL
? le32_to_cpu(d.v->d_child_subvol) == inode->bi_subvol
: le64_to_cpu(d.v->d_inum) == inode->bi_inum;
}
static int check_inode_deleted_list(struct btree_trans *trans, struct bpos p)
{
struct btree_iter iter;
@ -924,13 +953,14 @@ static int check_inode_deleted_list(struct btree_trans *trans, struct bpos p)
return ret;
}
static int check_inode_dirent_inode(struct btree_trans *trans, struct bkey_s_c inode_k,
static int check_inode_dirent_inode(struct btree_trans *trans,
struct bch_inode_unpacked *inode,
u32 inode_snapshot, bool *write_inode)
bool *write_inode)
{
struct bch_fs *c = trans->c;
struct printbuf buf = PRINTBUF;
u32 inode_snapshot = inode->bi_snapshot;
struct btree_iter dirent_iter = {};
struct bkey_s_c_dirent d = inode_get_dirent(trans, &dirent_iter, inode, &inode_snapshot);
int ret = bkey_err(d);
@ -940,13 +970,13 @@ static int check_inode_dirent_inode(struct btree_trans *trans, struct bkey_s_c i
if (fsck_err_on(ret,
trans, inode_points_to_missing_dirent,
"inode points to missing dirent\n%s",
(bch2_bkey_val_to_text(&buf, c, inode_k), buf.buf)) ||
fsck_err_on(!ret && !dirent_points_to_inode(d, inode),
(bch2_inode_unpacked_to_text(&buf, inode), buf.buf)) ||
fsck_err_on(!ret && dirent_points_to_inode_nowarn(d, inode),
trans, inode_points_to_wrong_dirent,
"inode points to dirent that does not point back:\n%s",
(bch2_bkey_val_to_text(&buf, c, inode_k),
prt_newline(&buf),
bch2_bkey_val_to_text(&buf, c, d.s_c), buf.buf))) {
"%s",
(printbuf_reset(&buf),
dirent_inode_mismatch_msg(&buf, c, d, inode),
buf.buf))) {
/*
* We just clear the backpointer fields for now. If we find a
* dirent that points to this inode in check_dirents(), we'll
@ -1145,7 +1175,7 @@ static int check_inode(struct btree_trans *trans,
}
if (u.bi_dir || u.bi_dir_offset) {
ret = check_inode_dirent_inode(trans, k, &u, k.k->p.snapshot, &do_update);
ret = check_inode_dirent_inode(trans, &u, &do_update);
if (ret)
goto err;
}
@ -2474,10 +2504,8 @@ static int check_path(struct btree_trans *trans, pathbuf *p, struct bkey_s_c ino
if (ret && !bch2_err_matches(ret, ENOENT))
break;
if (!ret && !dirent_points_to_inode(d, &inode)) {
if (!ret && (ret = dirent_points_to_inode(c, d, &inode)))
bch2_trans_iter_exit(trans, &dirent_iter);
ret = -BCH_ERR_ENOENT_dirent_doesnt_match_inode;
}
if (bch2_err_matches(ret, ENOENT)) {
ret = 0;