linux-kernel - [PATCH 4/8] bcachefs: BCH_FSCK_ERR_snapshot_key_missing_inode

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Message-ID: <20250502200002.1309862-5-kent.overstreet@linux.dev>
Date: Fri,  2 May 2025 15:59:56 -0400
From: Kent Overstreet <kent.overstreet@...ux.dev>
To: linux-bcachefs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Kent Overstreet <kent.overstreet@...ux.dev>
Subject: [PATCH 4/8] bcachefs: BCH_FSCK_ERR_snapshot_key_missing_inode_snapshot

We're going to be doing some snapshot deletion performance improvements,
and those will strictly require that if an extent/dirent/xattr is
present, an inode is present in that snapshot ID.

We already check for this, but we don't repair it on disk: this patch
adds that repair and turns it into a real fsck_err().

Signed-off-by: Kent Overstreet <kent.overstreet@...ux.dev>
---
 fs/bcachefs/fsck.c             | 44 ++++++++++++++++------------------
 fs/bcachefs/sb-errors_format.h |  3 ++-
 2 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/fs/bcachefs/fsck.c b/fs/bcachefs/fsck.c
index f0aa3c7479e1..dd88113a7c70 100644
--- a/fs/bcachefs/fsck.c
+++ b/fs/bcachefs/fsck.c
@@ -862,9 +862,9 @@ static int get_inodes_all_snapshots(struct btree_trans *trans,
 }
 
 static struct inode_walker_entry *
-lookup_inode_for_snapshot(struct bch_fs *c, struct inode_walker *w, struct bkey_s_c k)
+lookup_inode_for_snapshot(struct btree_trans *trans, struct inode_walker *w, struct bkey_s_c k)
 {
-	bool is_whiteout = k.k->type == KEY_TYPE_whiteout;
+	struct bch_fs *c = trans->c;
 
 	struct inode_walker_entry *i;
 	__darray_for_each(w->inodes, i)
@@ -875,34 +875,32 @@ lookup_inode_for_snapshot(struct bch_fs *c, struct inode_walker *w, struct bkey_
 found:
 	BUG_ON(k.k->p.snapshot > i->inode.bi_snapshot);
 
-	if (k.k->p.snapshot != i->inode.bi_snapshot && !is_whiteout) {
-		struct inode_walker_entry new = *i;
-
-		new.inode.bi_snapshot	= k.k->p.snapshot;
-		new.count		= 0;
-		new.i_size		= 0;
-
-		struct printbuf buf = PRINTBUF;
-		bch2_bkey_val_to_text(&buf, c, k);
+	struct printbuf buf = PRINTBUF;
+	int ret = 0;
 
-		bch_info(c, "have key for inode %llu:%u but have inode in ancestor snapshot %u\n"
+	if (fsck_err_on(k.k->p.snapshot != i->inode.bi_snapshot,
+			trans, snapshot_key_missing_inode_snapshot,
+			 "have key for inode %llu:%u but have inode in ancestor snapshot %u\n"
 			 "unexpected because we should always update the inode when we update a key in that inode\n"
 			 "%s",
-			 w->last_pos.inode, k.k->p.snapshot, i->inode.bi_snapshot, buf.buf);
-		printbuf_exit(&buf);
+			 w->last_pos.inode, k.k->p.snapshot, i->inode.bi_snapshot,
+			 (bch2_bkey_val_to_text(&buf, c, k),
+			  buf.buf))) {
+		struct bch_inode_unpacked new = i->inode;
 
-		while (i > w->inodes.data && i[-1].inode.bi_snapshot > k.k->p.snapshot)
-			--i;
+		new.bi_snapshot = k.k->p.snapshot;
 
-		size_t pos = i - w->inodes.data;
-		int ret = darray_insert_item(&w->inodes, pos, new);
-		if (ret)
-			return ERR_PTR(ret);
-
-		i = w->inodes.data + pos;
+		ret = __bch2_fsck_write_inode(trans, &new) ?:
+			bch2_trans_commit(trans, NULL, NULL, 0) ?:
+			-BCH_ERR_transaction_restart_nested;
+		goto fsck_err;
 	}
 
+	printbuf_exit(&buf);
 	return i;
+fsck_err:
+	printbuf_exit(&buf);
+	return ERR_PTR(ret);
 }
 
 static struct inode_walker_entry *walk_inode(struct btree_trans *trans,
@@ -917,7 +915,7 @@ static struct inode_walker_entry *walk_inode(struct btree_trans *trans,
 
 	w->last_pos = k.k->p;
 
-	return lookup_inode_for_snapshot(trans->c, w, k);
+	return lookup_inode_for_snapshot(trans, w, k);
 }
 
 static int get_visible_inodes(struct btree_trans *trans,
diff --git a/fs/bcachefs/sb-errors_format.h b/fs/bcachefs/sb-errors_format.h
index 6389f6e0f8dc..82bc1906aa00 100644
--- a/fs/bcachefs/sb-errors_format.h
+++ b/fs/bcachefs/sb-errors_format.h
@@ -216,6 +216,7 @@ enum bch_fsck_flags {
 	x(inode_str_hash_invalid,				194,	0)		\
 	x(inode_v3_fields_start_bad,				195,	0)		\
 	x(inode_snapshot_mismatch,				196,	0)		\
+	x(snapshot_key_missing_inode_snapshot,			314,	FSCK_AUTOFIX)	\
 	x(inode_unlinked_but_clean,				197,	0)		\
 	x(inode_unlinked_but_nlink_nonzero,			198,	0)		\
 	x(inode_unlinked_and_not_open,				281,	0)		\
@@ -323,7 +324,7 @@ enum bch_fsck_flags {
 	x(dirent_stray_data_after_cf_name,			305,	0)		\
 	x(rebalance_work_incorrectly_set,			309,	FSCK_AUTOFIX)	\
 	x(rebalance_work_incorrectly_unset,			310,	FSCK_AUTOFIX)	\
-	x(MAX,							314,	0)
+	x(MAX,							315,	0)
 
 enum bch_sb_error_id {
 #define x(t, n, ...) BCH_FSCK_ERR_##t = n,
-- 
2.49.0