bcachefs: dirent_points_to_inode() now warns on mismatch

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>

diff --git a/fs/bcachefs/fsck.c b/fs/bcachefs/fsck.c
index 9c10eeeb0bcb889a50f8463e97ad35b2ba9d0ea8..0e397d0ef3dd6e9e769f3400006f598947ae9909 100644 (file)
--- a/fs/bcachefs/fsck.c
+++ b/fs/bcachefs/fsck.c
@@ -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;