When number of free space in the journal is very low, the arithmetic in
jbd2_log_space_left() could underflow resulting in very high number of
free blocks and thus triggering assertion failure in transaction commit
code complaining there's not enough space in the journal:
J_ASSERT(journal->j_free > 1);
Properly check for the low number of free blocks.
CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
include/linux/jbd2.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 603fbc4e2f70..10e6049c0ba9 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1582,7 +1582,7 @@ static inline int jbd2_space_needed(journal_t *journal)
static inline unsigned long jbd2_log_space_left(journal_t *journal)
{
/* Allow for rounding errors */
- unsigned long free = journal->j_free - 32;
+ long free = journal->j_free - 32;
if (journal->j_committing_transaction) {
unsigned long committing = atomic_read(&journal->
@@ -1591,7 +1591,7 @@ static inline unsigned long jbd2_log_space_left(journal_t *journal)
/* Transaction + control blocks */
free -= committing + (committing >> JBD2_CONTROL_BLOCKS_SHIFT);
}
- return free;
+ return max_t(long, free, 0);
}
/*
--
2.16.4
