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jbd2: don't call get_bh() before calling __jbd2_journal_remove_checkpoint()

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The __jbd2_journal_remove_checkpoint() doesn't require an elevated
b_count; indeed, until the jh structure gets released by the call to
jbd2_journal_put_journal_head(), the bh's b_count is elevated by
virtue of the existence of the jh structure.

Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2014-09-04 18:09:22 -04:00
parent 754cfed6bb
commit dc6e8d669c
1 changed files with 5 additions and 14 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

19
fs/jbd2/checkpoint.c
View file

@ -96,15 +96,8 @@ static int __try_to_free_cp_buf(struct journal_head *jh)
if (jh->b_transaction == NULL && !buffer_locked(bh) &&
!buffer_dirty(bh) && !buffer_write_io_error(bh)) {
/*
* Get our reference so that bh cannot be freed before
* we unlock it
*/
get_bh(bh);
JBUFFER_TRACE(jh, "remove from checkpoint list");
ret = __jbd2_journal_remove_checkpoint(jh) + 1;
BUFFER_TRACE(bh, "release");
__brelse(bh);
}
return ret;
}
@ -216,7 +209,7 @@ int jbd2_log_do_checkpoint(journal_t *journal)
struct buffer_head *bh;
transaction_t *transaction;
tid_t this_tid;
int result, batch_count = 0, done = 0;
int result, batch_count = 0;
jbd_debug(1, "Start checkpoint\n");
@ -291,11 +284,9 @@ int jbd2_log_do_checkpoint(journal_t *journal)
if (!buffer_dirty(bh)) {
if (unlikely(buffer_write_io_error(bh)) && !result)
result = -EIO;
get_bh(bh);
BUFFER_TRACE(bh, "remove from checkpoint");
__jbd2_journal_remove_checkpoint(jh);
spin_unlock(&journal->j_list_lock);
__brelse(bh);
goto retry;
}
/*
@ -338,12 +329,12 @@ int jbd2_log_do_checkpoint(journal_t *journal)
transaction->t_tid != this_tid)
goto out;
while (!done && transaction->t_checkpoint_io_list) {
while (transaction->t_checkpoint_io_list) {
jh = transaction->t_checkpoint_io_list;
bh = jh2bh(jh);
get_bh(bh);
if (buffer_locked(bh)) {
spin_unlock(&journal->j_list_lock);
get_bh(bh);
wait_on_buffer(bh);
/* the journal_head may have gone by now */
BUFFER_TRACE(bh, "brelse");
@ -359,8 +350,8 @@ int jbd2_log_do_checkpoint(journal_t *journal)
* know that it has been written out and so we can
* drop it from the list
*/
done = __jbd2_journal_remove_checkpoint(jh);
__brelse(bh);
if (__jbd2_journal_remove_checkpoint(jh))
break;
}
out:
spin_unlock(&journal->j_list_lock);