From: zhanchengbin <zhanchengbin1@xxxxxxxxxx>
Following process will make data lost and could lead to a filesystem
corrupted problem:
1. jh(bh) is inserted into T1->t_checkpoint_list, bh is dirty, and
jh->b_transaction = NULL
2. T1 is added into journal->j_checkpoint_transactions.
3. Get bh prepare to write while doing checkpoing:
PA PB
do_get_write_access jbd2_log_do_checkpoint
spin_lock(&jh->b_state_lock)
if (buffer_dirty(bh))
clear_buffer_dirty(bh) // clear buffer dirty
set_buffer_jbddirty(bh)
transaction =
journal->j_checkpoint_transactions
jh = transaction->t_checkpoint_list
if (!buffer_dirty(bh))
__jbd2_journal_remove_checkpoint(jh)
// bh won't be flushed
jbd2_cleanup_journal_tail
__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved)
4. Aborting journal/Power-cut before writing latest bh on journal area.
In this way we get a corrupted filesystem with bh'data lost.
Fix it by wrapping clear_buffer_dirty(bh) and jh->b_transaction setting
into journal->j_list_lock, so that jbd2_log_do_checkpoint() will wait
until jh's new transaction fininshed even bh is currently not dirty.
Cc: <stable@xxxxxxxxxx>
Signed-off-by: zhanchengbin <zhanchengbin1@xxxxxxxxxx>
Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
Signed-off-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
---
This is a quick fix, I need some suggestions about this patch, whether
it will import new problems if this patch is applied.
Yi suggests that the formal solution could be splitting
journal->j_list_lock into two locks: one protects checkpoint list and
the other one for other lists. Besides, jh->b_state_lock should be
held while traversing transaction->t_checkpoint_list in
jbd2_log_do_checkpoint()/journal_shrink_one_cp_list().
fs/jbd2/transaction.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 6a404ac1c178..d22460001d6b 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -990,6 +990,7 @@ do_get_write_access(handle_t *handle, struct journal_head *jh,
start_lock = jiffies;
lock_buffer(bh);
spin_lock(&jh->b_state_lock);
+ spin_lock(&journal->j_list_lock);
/* If it takes too long to lock the buffer, trace it */
time_lock = jbd2_time_diff(start_lock, jiffies);
@@ -1039,6 +1040,7 @@ do_get_write_access(handle_t *handle, struct journal_head *jh,
error = -EROFS;
if (is_handle_aborted(handle)) {
+ spin_unlock(&journal->j_list_lock);
spin_unlock(&jh->b_state_lock);
goto out;
}
@@ -1049,8 +1051,10 @@ do_get_write_access(handle_t *handle, struct journal_head *jh,
* b_next_transaction points to it
*/
if (jh->b_transaction == transaction ||
- jh->b_next_transaction == transaction)
+ jh->b_next_transaction == transaction) {
+ spin_unlock(&journal->j_list_lock);
goto done;
+ }
/*
* this is the first time this transaction is touching this buffer,
@@ -1073,11 +1077,11 @@ do_get_write_access(handle_t *handle, struct journal_head *jh,
* Paired with barrier in jbd2_write_access_granted()
*/
smp_wmb();
- spin_lock(&journal->j_list_lock);
__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
spin_unlock(&journal->j_list_lock);
goto done;
}
+ spin_unlock(&journal->j_list_lock);
/*
* If there is already a copy-out version of this buffer, then we don't
* need to make another one
--
2.31.1
