re: [PATCH] Change ll_rw_block() calls in JBD

Zoltan Menyhart
2006-05-18T08:26:11Z

> We must be sure that the current data in buffer are sent to disk.
> Hence we have to call ll_rw_block() with SWRITE.

Let's consider the following case:

while (commit_transaction->t_sync_datalist) {
...

// Assume a "bh" got locked before starting this loop

if (buffer_locked(bh)) {
...
__journal_temp_unlink_buffer(jh);
__journal_file_buffer(jh, commit_transaction, BJ_Locked);
} else ...
}
...
while (commit_transaction->t_locked_list) {
...

// Assume our "bh" is not locked any more
// Nothing has happened to this "bh", someone just wanted
// to look at it in a safe way

if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) {
__journal_unfile_buffer(jh);
jbd_unlock_bh_state(bh);
journal_remove_journal_head(bh);
put_bh(bh);
} else ...
}

I.e. having an already locked "bh", it is missed out from the log.

Regards,

Zoltan Menyhart