[PATCH] bcachefs: fix deadlock in journal_entry_open()

From: Jeongjun Park
Date: Wed Jan 29 2025 - 12:17:59 EST


In the previous commit b3d82c2f2761, code was added to prevent journal sequence
overflow. Among them, the code added to journal_entry_open() uses the
bch2_fs_fatal_err_on() function to handle errors.

However, __journal_res_get() , which calls journal_entry_open() , calls
journal_entry_open() while holding journal->lock , but bch2_fs_fatal_err_on()
internally tries to acquire journal->lock , which results in a deadlock.

Therefore, we need to use bch_err() instead of bch2_fs_fatal_err_on() to
prevent deadlock.

Fixes: b3d82c2f2761 ("bcachefs: Guard against journal seq overflow")
Signed-off-by: Jeongjun Park <aha310510@xxxxxxxxx>
---
fs/bcachefs/journal.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
index 2cd20114b74b..38ba5ab785c3 100644
--- a/fs/bcachefs/journal.c
+++ b/fs/bcachefs/journal.c
@@ -382,9 +382,10 @@ static int journal_entry_open(struct journal *j)
if (nr_unwritten_journal_entries(j) == ARRAY_SIZE(j->buf))
return JOURNAL_ERR_max_in_flight;

- if (bch2_fs_fatal_err_on(journal_cur_seq(j) >= JOURNAL_SEQ_MAX,
- c, "cannot start: journal seq overflow"))
+ if (journal_cur_seq(j) >= JOURNAL_SEQ_MAX) {
+ bch_err(c, "cannot start: journal seq overflow");
return JOURNAL_ERR_insufficient_devices; /* -EROFS */
+ }

BUG_ON(!j->cur_entry_sectors);

--