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bcachefs: fix deadlock in journal_entry_open()

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In the previous commit b3d82c2f27, 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.

So we need to add a locked helper to handle fatal errors even when the
journal->lock is held.

Fixes: b3d82c2f27 ("bcachefs: Guard against journal seq overflow")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Jeongjun Park
2025-02-02 15:13:51 +09:00
committed by Kent Overstreet
parent 6b37037d6d
commit 2ef995df0c
4 changed files with 28 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
fs/bcachefs/journal.c
View File

@@ -319,6 +319,16 @@ void bch2_journal_halt(struct journal *j)
spin_unlock(&j->lock);
}
void bch2_journal_halt_locked(struct journal *j)
{
lockdep_assert_held(&j->lock);
__journal_entry_close(j, JOURNAL_ENTRY_ERROR_VAL, true);
if (!j->err_seq)
j->err_seq = journal_cur_seq(j);
journal_wake(j);
}
static bool journal_entry_want_write(struct journal *j)
{
bool ret = !journal_entry_is_open(j) ||
@@ -381,9 +391,12 @@ 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");
if (bch2_fs_emergency_read_only_locked(c))
bch_err(c, "fatal error - emergency read only");
return JOURNAL_ERR_insufficient_devices; /* -EROFS */
}
BUG_ON(!j->cur_entry_sectors);

1
fs/bcachefs/journal.h
View File

@@ -409,6 +409,7 @@ bool bch2_journal_noflush_seq(struct journal *, u64, u64);
int bch2_journal_meta(struct journal *);
void bch2_journal_halt(struct journal *);
void bch2_journal_halt_locked(struct journal *);
static inline int bch2_journal_error(struct journal *j)
{

11
fs/bcachefs/super.c
View File

@@ -411,6 +411,17 @@ bool bch2_fs_emergency_read_only(struct bch_fs *c)
return ret;
}
bool bch2_fs_emergency_read_only_locked(struct bch_fs *c)
{
bool ret = !test_and_set_bit(BCH_FS_emergency_ro, &c->flags);
bch2_journal_halt_locked(&c->journal);
bch2_fs_read_only_async(c);
wake_up(&bch2_read_only_wait);
return ret;
}
static int bch2_fs_read_write_late(struct bch_fs *c)
{
int ret;

1
fs/bcachefs/super.h
View File

@@ -29,6 +29,7 @@ int bch2_dev_resize(struct bch_fs *, struct bch_dev *, u64);
struct bch_dev *bch2_dev_lookup(struct bch_fs *, const char *);
bool bch2_fs_emergency_read_only(struct bch_fs *);
bool bch2_fs_emergency_read_only_locked(struct bch_fs *);
void bch2_fs_read_only(struct bch_fs *);
int bch2_fs_read_write(struct bch_fs *);