bcachefs: bch2_inum_to_path()

Add a function for walking backpointers to find a path from a given
inode number, and convert various error messages to use it.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/errcode.h

@@ -116,6 +116,7 @@
 	x(ENOENT,			ENOENT_dirent_doesnt_match_inode)	\
 	x(ENOENT,			ENOENT_dev_not_found)			\
 	x(ENOENT,			ENOENT_dev_idx_not_found)		\
+	x(ENOENT,			ENOENT_inode_no_backpointer)		\
 	x(ENOTEMPTY,			ENOTEMPTY_dir_not_empty)		\
 	x(ENOTEMPTY,			ENOTEMPTY_subvol_not_empty)		\
 	x(EEXIST,			EEXIST_str_hash_set)			\

fs/bcachefs/error.c

@@ -3,6 +3,7 @@
 #include "btree_cache.h"
 #include "btree_iter.h"
 #include "error.h"
+#include "fs-common.h"
 #include "journal.h"
 #include "recovery_passes.h"
 #include "super.h"
@@ -515,3 +516,36 @@ void bch2_flush_fsck_errs(struct bch_fs *c)
 
 	mutex_unlock(&c->fsck_error_msgs_lock);
 }
+
+int bch2_inum_err_msg_trans(struct btree_trans *trans, struct printbuf *out, subvol_inum inum)
+{
+	u32 restart_count = trans->restart_count;
+	int ret = 0;
+
+	/* XXX: we don't yet attempt to print paths when we don't know the subvol */
+	if (inum.subvol)
+		ret = lockrestart_do(trans, bch2_inum_to_path(trans, inum, out));
+	if (!inum.subvol || ret)
+		prt_printf(out, "inum %llu:%llu", inum.subvol, inum.inum);
+
+	return trans_was_restarted(trans, restart_count);
+}
+
+int bch2_inum_offset_err_msg_trans(struct btree_trans *trans, struct printbuf *out,
+				    subvol_inum inum, u64 offset)
+{
+	int ret = bch2_inum_err_msg_trans(trans, out, inum);
+	prt_printf(out, " offset %llu: ", offset);
+	return ret;
+}
+
+void bch2_inum_err_msg(struct bch_fs *c, struct printbuf *out, subvol_inum inum)
+{
+	bch2_trans_run(c, bch2_inum_err_msg_trans(trans, out, inum));
+}
+
+void bch2_inum_offset_err_msg(struct bch_fs *c, struct printbuf *out,
+			      subvol_inum inum, u64 offset)
+{
+	bch2_trans_run(c, bch2_inum_offset_err_msg_trans(trans, out, inum, offset));
+}

fs/bcachefs/error.h

@@ -238,4 +238,10 @@ void bch2_io_error(struct bch_dev *, enum bch_member_error_type);
 	_ret;								\
 })
 
+int bch2_inum_err_msg_trans(struct btree_trans *, struct printbuf *, subvol_inum);
+int bch2_inum_offset_err_msg_trans(struct btree_trans *, struct printbuf *, subvol_inum, u64);
+
+void bch2_inum_err_msg(struct bch_fs *, struct printbuf *, subvol_inum);
+void bch2_inum_offset_err_msg(struct bch_fs *, struct printbuf *, subvol_inum, u64);
+
 #endif /* _BCACHEFS_ERROR_H */

fs/bcachefs/fs-common.c

@@ -548,3 +548,84 @@ int bch2_rename_trans(struct btree_trans *trans,
 	bch2_trans_iter_exit(trans, &src_dir_iter);
 	return ret;
 }
+
+static inline void prt_bytes_reversed(struct printbuf *out, const void *b, unsigned n)
+{
+	bch2_printbuf_make_room(out, n);
+
+	unsigned can_print = min(n, printbuf_remaining(out));
+
+	b += n;
+
+	for (unsigned i = 0; i < can_print; i++)
+		out->buf[out->pos++] = *((char *) --b);
+
+	printbuf_nul_terminate(out);
+}
+
+static inline void reverse_bytes(void *b, size_t n)
+{
+	char *e = b + n, *s = b;
+
+	while (s < e) {
+		--e;
+		swap(*s, *e);
+		s++;
+	}
+}
+
+/* XXX: we don't yet attempt to print paths when we don't know the subvol */
+int bch2_inum_to_path(struct btree_trans *trans, subvol_inum inum, struct printbuf *path)
+{
+	unsigned orig_pos = path->pos;
+	int ret = 0;
+
+	while (!(inum.subvol == BCACHEFS_ROOT_SUBVOL &&
+		 inum.inum   == BCACHEFS_ROOT_INO)) {
+		struct bch_inode_unpacked inode;
+		ret = bch2_inode_find_by_inum_trans(trans, inum, &inode);
+		if (ret)
+			goto err;
+
+		if (!inode.bi_dir && !inode.bi_dir_offset) {
+			ret = -BCH_ERR_ENOENT_inode_no_backpointer;
+			goto err;
+		}
+
+		u32 snapshot;
+		ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
+		if (ret)
+			goto err;
+
+		struct btree_iter d_iter;
+		struct bkey_s_c_dirent d = bch2_bkey_get_iter_typed(trans, &d_iter,
+				BTREE_ID_dirents, SPOS(inode.bi_dir, inode.bi_dir_offset, snapshot),
+				0, dirent);
+		ret = bkey_err(d.s_c);
+		if (ret)
+			goto err;
+
+		struct qstr dirent_name = bch2_dirent_get_name(d);
+		prt_bytes_reversed(path, dirent_name.name, dirent_name.len);
+
+		prt_char(path, '/');
+
+		if (d.v->d_type == DT_SUBVOL)
+			inum.subvol = le32_to_cpu(d.v->d_parent_subvol);
+		inum.inum = d.k->p.inode;
+
+		bch2_trans_iter_exit(trans, &d_iter);
+	}
+
+	if (orig_pos == path->pos)
+		prt_char(path, '/');
+
+	ret = path->allocation_failure ? -ENOMEM : 0;
+	if (ret)
+		goto err;
+
+	reverse_bytes(path->buf + orig_pos, path->pos - orig_pos);
+	return 0;
+err:
+	return ret;
+}

fs/bcachefs/fs-common.h

@@ -42,4 +42,6 @@ int bch2_rename_trans(struct btree_trans *,
 bool bch2_reinherit_attrs(struct bch_inode_unpacked *,
 			  struct bch_inode_unpacked *);
 
+int bch2_inum_to_path(struct btree_trans *, subvol_inum, struct printbuf *);
+
 #endif /* _BCACHEFS_FS_COMMON_H */

fs/bcachefs/fs-io-buffered.c

@@ -231,10 +231,12 @@ static void bchfs_read(struct btree_trans *trans,
 	bch2_trans_iter_exit(trans, &iter);
 
 	if (ret) {
-		bch_err_inum_offset_ratelimited(c,
-				iter.pos.inode,
-				iter.pos.offset << 9,
-				"read error %i from btree lookup", ret);
+		struct printbuf buf = PRINTBUF;
+		bch2_inum_offset_err_msg_trans(trans, &buf, inum, iter.pos.offset << 9);
+		prt_printf(&buf, "read error %i from btree lookup", ret);
+		bch_err_ratelimited(c, "%s", buf.buf);
+		printbuf_exit(&buf);
+
 		rbio->bio.bi_status = BLK_STS_IOERR;
 		bio_endio(&rbio->bio);
 	}

fs/bcachefs/fsck.c

@@ -212,6 +212,7 @@ static int lookup_lostfound(struct btree_trans *trans, u32 snapshot,
 {
 	struct bch_fs *c = trans->c;
 	struct qstr lostfound_str = QSTR("lost+found");
+	struct btree_iter lostfound_iter = { NULL };
 	u64 inum = 0;
 	unsigned d_type = 0;
 	int ret;
@@ -290,11 +291,16 @@ static int lookup_lostfound(struct btree_trans *trans, u32 snapshot,
 	 * XXX: we could have a nicer log message here  if we had a nice way to
 	 * walk backpointers to print a path
 	 */
-	bch_notice(c, "creating lost+found in subvol %llu snapshot %u",
-		   root_inum.subvol, le32_to_cpu(st.root_snapshot));
+	struct printbuf path = PRINTBUF;
+	ret = bch2_inum_to_path(trans, root_inum, &path);
+	if (ret)
+		goto err;
+
+	bch_notice(c, "creating %s/lost+found in subvol %llu snapshot %u",
+		   path.buf, root_inum.subvol, snapshot);
+	printbuf_exit(&path);
 
 	u64 now = bch2_current_time(c);
-	struct btree_iter lostfound_iter = { NULL };
 	u64 cpu = raw_smp_processor_id();
 
 	bch2_inode_init_early(c, lostfound);

fs/bcachefs/io_misc.c

@@ -113,11 +113,13 @@ int bch2_extent_fallocate(struct btree_trans *trans,
 err:
 	if (!ret && sectors_allocated)
 		bch2_increment_clock(c, sectors_allocated, WRITE);
-	if (should_print_err(ret))
-		bch_err_inum_offset_ratelimited(c,
-			inum.inum,
-			iter->pos.offset << 9,
-			"%s(): error: %s", __func__, bch2_err_str(ret));
+	if (should_print_err(ret)) {
+		struct printbuf buf = PRINTBUF;
+		bch2_inum_offset_err_msg_trans(trans, &buf, inum, iter->pos.offset << 9);
+		prt_printf(&buf, "fallocate error: %s", bch2_err_str(ret));
+		bch_err_ratelimited(c, "%s", buf.buf);
+		printbuf_exit(&buf);
+	}
 err_noprint:
 	bch2_open_buckets_put(c, &open_buckets);
 	bch2_disk_reservation_put(c, &disk_res);

fs/bcachefs/io_read.c

@@ -322,6 +322,20 @@ static struct promote_op *promote_alloc(struct btree_trans *trans,
 
 /* Read */
 
+static int bch2_read_err_msg_trans(struct btree_trans *trans, struct printbuf *out,
+				   struct bch_read_bio *rbio, struct bpos read_pos)
+{
+	return bch2_inum_offset_err_msg_trans(trans, out,
+		(subvol_inum) { rbio->subvol, read_pos.inode },
+		read_pos.offset << 9);
+}
+
+static void bch2_read_err_msg(struct bch_fs *c, struct printbuf *out,
+			      struct bch_read_bio *rbio, struct bpos read_pos)
+{
+	bch2_trans_run(c, bch2_read_err_msg_trans(trans, out, rbio, read_pos));
+}
+
 #define READ_RETRY_AVOID	1
 #define READ_RETRY		2
 #define READ_ERR		3
@@ -500,6 +514,29 @@ static void bch2_rbio_error(struct bch_read_bio *rbio, int retry,
 	}
 }
 
+static void bch2_read_io_err(struct work_struct *work)
+{
+	struct bch_read_bio *rbio =
+		container_of(work, struct bch_read_bio, work);
+	struct bio *bio = &rbio->bio;
+	struct bch_fs *c	= rbio->c;
+	struct bch_dev *ca = rbio->have_ioref ? bch2_dev_have_ref(c, rbio->pick.ptr.dev) : NULL;
+	struct printbuf buf = PRINTBUF;
+
+	bch2_read_err_msg(c, &buf, rbio, rbio->read_pos);
+	prt_printf(&buf, "data read error: %s", bch2_blk_status_to_str(bio->bi_status));
+
+	if (ca) {
+		bch2_io_error(ca, BCH_MEMBER_ERROR_read);
+		bch_err_ratelimited(ca, "%s", buf.buf);
+	} else {
+		bch_err_ratelimited(c, "%s", buf.buf);
+	}
+
+	printbuf_exit(&buf);
+	bch2_rbio_error(rbio, READ_RETRY_AVOID, bio->bi_status);
+}
+
 static int __bch2_rbio_narrow_crcs(struct btree_trans *trans,
 				   struct bch_read_bio *rbio)
 {
@@ -563,6 +600,73 @@ static noinline void bch2_rbio_narrow_crcs(struct bch_read_bio *rbio)
 			     __bch2_rbio_narrow_crcs(trans, rbio));
 }
 
+static void bch2_read_csum_err(struct work_struct *work)
+{
+	struct bch_read_bio *rbio =
+		container_of(work, struct bch_read_bio, work);
+	struct bch_fs *c	= rbio->c;
+	struct bio *src		= &rbio->bio;
+	struct bch_extent_crc_unpacked crc = rbio->pick.crc;
+	struct nonce nonce = extent_nonce(rbio->version, crc);
+	struct bch_csum csum = bch2_checksum_bio(c, crc.csum_type, nonce, src);
+	struct printbuf buf = PRINTBUF;
+
+	bch2_read_err_msg(c, &buf, rbio, rbio->read_pos);
+	prt_str(&buf, "data ");
+	bch2_csum_err_msg(&buf, crc.csum_type, rbio->pick.crc.csum, csum);
+
+	struct bch_dev *ca = rbio->have_ioref ? bch2_dev_have_ref(c, rbio->pick.ptr.dev) : NULL;
+	if (ca) {
+		bch2_io_error(ca, BCH_MEMBER_ERROR_checksum);
+		bch_err_ratelimited(ca, "%s", buf.buf);
+	} else {
+		bch_err_ratelimited(c, "%s", buf.buf);
+	}
+
+	bch2_rbio_error(rbio, READ_RETRY_AVOID, BLK_STS_IOERR);
+	printbuf_exit(&buf);
+}
+
+static void bch2_read_decompress_err(struct work_struct *work)
+{
+	struct bch_read_bio *rbio =
+		container_of(work, struct bch_read_bio, work);
+	struct bch_fs *c	= rbio->c;
+	struct printbuf buf = PRINTBUF;
+
+	bch2_read_err_msg(c, &buf, rbio, rbio->read_pos);
+	prt_str(&buf, "decompression error");
+
+	struct bch_dev *ca = rbio->have_ioref ? bch2_dev_have_ref(c, rbio->pick.ptr.dev) : NULL;
+	if (ca)
+		bch_err_ratelimited(ca, "%s", buf.buf);
+	else
+		bch_err_ratelimited(c, "%s", buf.buf);
+
+	bch2_rbio_error(rbio, READ_ERR, BLK_STS_IOERR);
+	printbuf_exit(&buf);
+}
+
+static void bch2_read_decrypt_err(struct work_struct *work)
+{
+	struct bch_read_bio *rbio =
+		container_of(work, struct bch_read_bio, work);
+	struct bch_fs *c	= rbio->c;
+	struct printbuf buf = PRINTBUF;
+
+	bch2_read_err_msg(c, &buf, rbio, rbio->read_pos);
+	prt_str(&buf, "decrypt error");
+
+	struct bch_dev *ca = rbio->have_ioref ? bch2_dev_have_ref(c, rbio->pick.ptr.dev) : NULL;
+	if (ca)
+		bch_err_ratelimited(ca, "%s", buf.buf);
+	else
+		bch_err_ratelimited(c, "%s", buf.buf);
+
+	bch2_rbio_error(rbio, READ_ERR, BLK_STS_IOERR);
+	printbuf_exit(&buf);
+}
+
 /* Inner part that may run in process context */
 static void __bch2_read_endio(struct work_struct *work)
 {
@@ -669,33 +773,13 @@ static void __bch2_read_endio(struct work_struct *work)
 		goto out;
 	}
 
-	struct printbuf buf = PRINTBUF;
-	buf.atomic++;
-	prt_str(&buf, "data ");
-	bch2_csum_err_msg(&buf, crc.csum_type, rbio->pick.crc.csum, csum);
-
-	struct bch_dev *ca = rbio->have_ioref ? bch2_dev_have_ref(c, rbio->pick.ptr.dev) : NULL;
-	if (ca) {
-		bch_err_inum_offset_ratelimited(ca,
-			rbio->read_pos.inode,
-			rbio->read_pos.offset << 9,
-			"data %s", buf.buf);
-		bch2_io_error(ca, BCH_MEMBER_ERROR_checksum);
-	}
-	printbuf_exit(&buf);
-	bch2_rbio_error(rbio, READ_RETRY_AVOID, BLK_STS_IOERR);
+	bch2_rbio_punt(rbio, bch2_read_csum_err, RBIO_CONTEXT_UNBOUND, system_unbound_wq);
 	goto out;
 decompression_err:
-	bch_err_inum_offset_ratelimited(c, rbio->read_pos.inode,
-					rbio->read_pos.offset << 9,
-					"decompression error");
-	bch2_rbio_error(rbio, READ_ERR, BLK_STS_IOERR);
+	bch2_rbio_punt(rbio, bch2_read_decompress_err, RBIO_CONTEXT_UNBOUND, system_unbound_wq);
 	goto out;
 decrypt_err:
-	bch_err_inum_offset_ratelimited(c, rbio->read_pos.inode,
-					rbio->read_pos.offset << 9,
-					"decrypt error");
-	bch2_rbio_error(rbio, READ_ERR, BLK_STS_IOERR);
+	bch2_rbio_punt(rbio, bch2_read_decrypt_err, RBIO_CONTEXT_UNBOUND, system_unbound_wq);
 	goto out;
 }
 
@@ -716,16 +800,8 @@ static void bch2_read_endio(struct bio *bio)
 	if (!rbio->split)
 		rbio->bio.bi_end_io = rbio->end_io;
 
-	if (bio->bi_status) {
-		if (ca) {
-			bch_err_inum_offset_ratelimited(ca,
-				rbio->read_pos.inode,
-				rbio->read_pos.offset,
-				"data read error: %s",
-				bch2_blk_status_to_str(bio->bi_status));
-			bch2_io_error(ca, BCH_MEMBER_ERROR_read);
-		}
-		bch2_rbio_error(rbio, READ_RETRY_AVOID, bio->bi_status);
+	if (unlikely(bio->bi_status)) {
+		bch2_rbio_punt(rbio, bch2_read_io_err, RBIO_CONTEXT_UNBOUND, system_unbound_wq);
 		return;
 	}
 
@@ -832,25 +908,22 @@ int __bch2_read_extent(struct btree_trans *trans, struct bch_read_bio *orig,
 
 	if (unlikely(pick_ret < 0)) {
 		struct printbuf buf = PRINTBUF;
+		bch2_read_err_msg_trans(trans, &buf, orig, read_pos);
+		prt_printf(&buf, "no device to read from: %s\n  ", bch2_err_str(pick_ret));
 		bch2_bkey_val_to_text(&buf, c, k);
 
-		bch_err_inum_offset_ratelimited(c,
-				read_pos.inode, read_pos.offset << 9,
-				"no device to read from: %s\n  %s",
-				bch2_err_str(pick_ret),
-				buf.buf);
+		bch_err_ratelimited(c, "%s", buf.buf);
 		printbuf_exit(&buf);
 		goto err;
 	}
 
 	if (unlikely(bch2_csum_type_is_encryption(pick.crc.csum_type)) && !c->chacha20) {
 		struct printbuf buf = PRINTBUF;
+		bch2_read_err_msg_trans(trans, &buf, orig, read_pos);
+		prt_printf(&buf, "attempting to read encrypted data without encryption key\n  ");
 		bch2_bkey_val_to_text(&buf, c, k);
 
-		bch_err_inum_offset_ratelimited(c,
-				read_pos.inode, read_pos.offset << 9,
-				"attempting to read encrypted data without encryption key\n  %s",
-				buf.buf);
+		bch_err_ratelimited(c, "%s", buf.buf);
 		printbuf_exit(&buf);
 		goto err;
 	}
@@ -1036,11 +1109,15 @@ int __bch2_read_extent(struct btree_trans *trans, struct bch_read_bio *orig,
 	}
 
 	if (!rbio->pick.idx) {
-		if (!rbio->have_ioref) {
-			bch_err_inum_offset_ratelimited(c,
-					read_pos.inode,
-					read_pos.offset << 9,
-					"no device to read from");
+		if (unlikely(!rbio->have_ioref)) {
+			struct printbuf buf = PRINTBUF;
+			bch2_read_err_msg_trans(trans, &buf, rbio, read_pos);
+			prt_printf(&buf, "no device to read from:\n  ");
+			bch2_bkey_val_to_text(&buf, c, k);
+
+			bch_err_ratelimited(c, "%s", buf.buf);
+			printbuf_exit(&buf);
+
 			bch2_rbio_error(rbio, READ_RETRY_AVOID, BLK_STS_IOERR);
 			goto out;
 		}
@@ -1202,16 +1279,20 @@ void __bch2_read(struct bch_fs *c, struct bch_read_bio *rbio,
 	}
 
 	bch2_trans_iter_exit(trans, &iter);
-	bch2_trans_put(trans);
-	bch2_bkey_buf_exit(&sk, c);
 
 	if (ret) {
-		bch_err_inum_offset_ratelimited(c, inum.inum,
-						bvec_iter.bi_sector << 9,
-						"read error %i from btree lookup", ret);
+		struct printbuf buf = PRINTBUF;
+		bch2_inum_offset_err_msg_trans(trans, &buf, inum, bvec_iter.bi_sector << 9);
+		prt_printf(&buf, "read error %i from btree lookup", ret);
+		bch_err_ratelimited(c, "%s", buf.buf);
+		printbuf_exit(&buf);
+
 		rbio->bio.bi_status = BLK_STS_IOERR;
 		bch2_rbio_done(rbio);
 	}
+
+	bch2_trans_put(trans);
+	bch2_bkey_buf_exit(&sk, c);
 }
 
 void bch2_fs_io_read_exit(struct bch_fs *c)