From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Sat, 12 Oct 2024 02:50:48 +0000 (-0400)
Subject: bcachefs: bch2_journal_meta() takes ref on c->writes
X-Git-Tag: v6.14-rc1~204^2~240
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fb8c835b18d48dac953a5d755a8e90b0d8fb9c29;p=thirdparty%2Fkernel%2Flinux.git

bcachefs: bch2_journal_meta() takes ref on c->writes

This part of addressing
https://github.com/koverstreet/bcachefs/issues/656

where we're getting stuck in bch2_journal_meta() in the dump tool.

We shouldn't be invoking the journal without a ref on c->writes (if
we're not RW), and there's no reason for the dump tool to be going
read-write.

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

diff --git a/fs/bcachefs/bcachefs.h b/fs/bcachefs/bcachefs.h
index fbd89f91625d0..d4d95ef6791f3 100644
--- a/fs/bcachefs/bcachefs.h
+++ b/fs/bcachefs/bcachefs.h
@@ -688,6 +688,7 @@ struct btree_trans_buf {
 	((subvol_inum) { BCACHEFS_ROOT_SUBVOL,	BCACHEFS_ROOT_INO })
 
 #define BCH_WRITE_REFS()						\
+	x(journal)							\
 	x(trans)							\
 	x(write)							\
 	x(promote)							\
diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
index 2dc0d60c17450..2cf8f24d50cc2 100644
--- a/fs/bcachefs/journal.c
+++ b/fs/bcachefs/journal.c
@@ -831,19 +831,14 @@ out:
 	return ret;
 }
 
-int bch2_journal_meta(struct journal *j)
+static int __bch2_journal_meta(struct journal *j)
 {
-	struct journal_buf *buf;
-	struct journal_res res;
-	int ret;
-
-	memset(&res, 0, sizeof(res));
-
-	ret = bch2_journal_res_get(j, &res, jset_u64s(0), 0);
+	struct journal_res res = {};
+	int ret = bch2_journal_res_get(j, &res, jset_u64s(0), 0);
 	if (ret)
 		return ret;
 
-	buf = j->buf + (res.seq & JOURNAL_BUF_MASK);
+	struct journal_buf *buf = j->buf + (res.seq & JOURNAL_BUF_MASK);
 	buf->must_flush = true;
 
 	if (!buf->flush_time) {
@@ -856,6 +851,18 @@ int bch2_journal_meta(struct journal *j)
 	return bch2_journal_flush_seq(j, res.seq, TASK_UNINTERRUPTIBLE);
 }
 
+int bch2_journal_meta(struct journal *j)
+{
+	struct bch_fs *c = container_of(j, struct bch_fs, journal);
+
+	if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_journal))
+		return -EROFS;
+
+	int ret = __bch2_journal_meta(j);
+	bch2_write_ref_put(c, BCH_WRITE_REF_journal);
+	return ret;
+}
+
 /* block/unlock the journal: */
 
 void bch2_journal_unblock(struct journal *j)
@@ -1193,7 +1200,7 @@ void bch2_fs_journal_stop(struct journal *j)
 	 * Always write a new journal entry, to make sure the clock hands are up
 	 * to date (and match the superblock)
 	 */
-	bch2_journal_meta(j);
+	__bch2_journal_meta(j);
 
 	journal_quiesce(j);
 	cancel_delayed_work_sync(&j->write_work);
diff --git a/fs/bcachefs/recovery.c b/fs/bcachefs/recovery.c
index bc2fd174bb329..4316981890909 100644
--- a/fs/bcachefs/recovery.c
+++ b/fs/bcachefs/recovery.c
@@ -910,11 +910,9 @@ use_clean:
 	set_bit(BCH_FS_accounting_replay_done, &c->flags);
 
 	/* fsync if we fixed errors */
-	if (test_bit(BCH_FS_errors_fixed, &c->flags) &&
-	    bch2_write_ref_tryget(c, BCH_WRITE_REF_fsync)) {
+	if (test_bit(BCH_FS_errors_fixed, &c->flags)) {
 		bch2_journal_flush_all_pins(&c->journal);
 		bch2_journal_meta(&c->journal);
-		bch2_write_ref_put(c, BCH_WRITE_REF_fsync);
 	}
 
 	/* If we fixed errors, verify that fs is actually clean now: */