From: Jan Kara jack@suse.cz
commit add3efdd78b8a0478ce423bb9d4df6bd95e8b335 upstream.
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@vger.kernel.org Reviewed-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Jan Kara jack@suse.cz Link: https://lore.kernel.org/r/20191105164437.32602-1-jack@suse.cz Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/linux/jbd2.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -1584,7 +1584,7 @@ static inline int jbd2_space_needed(jour 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-> @@ -1593,7 +1593,7 @@ static inline unsigned long jbd2_log_spa /* Transaction + control blocks */ free -= committing + (committing >> JBD2_CONTROL_BLOCKS_SHIFT); } - return free; + return max_t(long, free, 0); }
/*