From 2aee59eb212266992c018f1ae2cf9c7f6c4ed1a9 Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Sat, 7 Sep 2024 16:31:47 -0400
Subject: [PATCH] bcachefs: improve error messages in bch2_ec_read_extent()

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
 fs/bcachefs/ec.c      | 38 +++++++++++++++++++++-----------------
 fs/bcachefs/ec.h      |  2 +-
 fs/bcachefs/io_read.c |  2 +-
 3 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/fs/bcachefs/ec.c b/fs/bcachefs/ec.c
index cc76ae3d2073..8af623b15ecf 100644
--- a/fs/bcachefs/ec.c
+++ b/fs/bcachefs/ec.c
@@ -829,13 +829,16 @@ err:
 }
 
 /* recovery read path: */
-int bch2_ec_read_extent(struct btree_trans *trans, struct bch_read_bio *rbio)
+int bch2_ec_read_extent(struct btree_trans *trans, struct bch_read_bio *rbio,
+			struct bkey_s_c orig_k)
 {
 	struct bch_fs *c = trans->c;
-	struct ec_stripe_buf *buf;
+	struct ec_stripe_buf *buf = NULL;
 	struct closure cl;
 	struct bch_stripe *v;
 	unsigned i, offset;
+	const char *msg = NULL;
+	struct printbuf msgbuf = PRINTBUF;
 	int ret = 0;
 
 	closure_init_stack(&cl);
@@ -848,32 +851,28 @@ int bch2_ec_read_extent(struct btree_trans *trans, struct bch_read_bio *rbio)
 
 	ret = lockrestart_do(trans, get_stripe_key_trans(trans, rbio->pick.ec.idx, buf));
 	if (ret) {
-		bch_err_ratelimited(c,
-			"error doing reconstruct read: error %i looking up stripe", ret);
-		kfree(buf);
-		return -BCH_ERR_stripe_reconstruct;
+		msg = "stripe not found";
+		goto err;
 	}
 
 	v = &bkey_i_to_stripe(&buf->key)->v;
 
 	if (!bch2_ptr_matches_stripe(v, rbio->pick)) {
-		bch_err_ratelimited(c,
-			"error doing reconstruct read: pointer doesn't match stripe");
-		ret = -BCH_ERR_stripe_reconstruct;
+		msg = "pointer doesn't match stripe";
 		goto err;
 	}
 
 	offset = rbio->bio.bi_iter.bi_sector - v->ptrs[rbio->pick.ec.block].offset;
 	if (offset + bio_sectors(&rbio->bio) > le16_to_cpu(v->sectors)) {
-		bch_err_ratelimited(c,
-			"error doing reconstruct read: read is bigger than stripe");
-		ret = -BCH_ERR_stripe_reconstruct;
+		msg = "read is bigger than stripe";
 		goto err;
 	}
 
 	ret = ec_stripe_buf_init(buf, offset, bio_sectors(&rbio->bio));
-	if (ret)
+	if (ret) {
+		msg = "-ENOMEM";
 		goto err;
+	}
 
 	for (i = 0; i < v->nr_blocks; i++)
 		ec_block_io(c, buf, REQ_OP_READ, i, &cl);
@@ -881,9 +880,7 @@ int bch2_ec_read_extent(struct btree_trans *trans, struct bch_read_bio *rbio)
 	closure_sync(&cl);
 
 	if (ec_nr_failed(buf) > v->nr_redundant) {
-		bch_err_ratelimited(c,
-			"error doing reconstruct read: unable to read enough blocks");
-		ret = -BCH_ERR_stripe_reconstruct;
+		msg = "unable to read enough blocks";
 		goto err;
 	}
 
@@ -895,10 +892,17 @@ int bch2_ec_read_extent(struct btree_trans *trans, struct bch_read_bio *rbio)
 
 	memcpy_to_bio(&rbio->bio, rbio->bio.bi_iter,
 		      buf->data[rbio->pick.ec.block] + ((offset - buf->offset) << 9));
-err:
+out:
 	ec_stripe_buf_exit(buf);
 	kfree(buf);
 	return ret;
+err:
+	bch2_bkey_val_to_text(&msgbuf, c, orig_k);
+	bch_err_ratelimited(c,
+			    "error doing reconstruct read: %s\n  %s", msg, msgbuf.buf);
+	printbuf_exit(&msgbuf);;
+	ret = -BCH_ERR_stripe_reconstruct;
+	goto out;
 }
 
 /* stripe bucket accounting: */
diff --git a/fs/bcachefs/ec.h b/fs/bcachefs/ec.h
index f02bb7d2e767..179a8674dac4 100644
--- a/fs/bcachefs/ec.h
+++ b/fs/bcachefs/ec.h
@@ -206,7 +206,7 @@ struct ec_stripe_head {
 	struct ec_stripe_new	*s;
 };
 
-int bch2_ec_read_extent(struct btree_trans *, struct bch_read_bio *);
+int bch2_ec_read_extent(struct btree_trans *, struct bch_read_bio *, struct bkey_s_c);
 
 void *bch2_writepoint_ec_buf(struct bch_fs *, struct write_point *);
 
diff --git a/fs/bcachefs/io_read.c b/fs/bcachefs/io_read.c
index b3fba16b157b..b2f50e74bb76 100644
--- a/fs/bcachefs/io_read.c
+++ b/fs/bcachefs/io_read.c
@@ -1092,7 +1092,7 @@ get_bio:
 		trans->notrace_relock_fail = true;
 	} else {
 		/* Attempting reconstruct read: */
-		if (bch2_ec_read_extent(trans, rbio)) {
+		if (bch2_ec_read_extent(trans, rbio, k)) {
 			bch2_rbio_error(rbio, READ_RETRY_AVOID, BLK_STS_IOERR);
 			goto out;
 		}