diff options
| author | Jan Kara <jack@suse.cz> | 2012-12-25 13:29:52 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2012-12-25 13:29:52 -0500 |
| commit | 53e872681fed6a43047e71bf927f77d06f467988 (patch) | |
| tree | 8b5061acbaf222b3f25df54ddbcaa0b1123c471a /fs/jbd2 | |
| parent | 4520fb3c3690f2643006d85f09ecb74554c10e95 (diff) | |
| download | linux-53e872681fed6a43047e71bf927f77d06f467988.tar.gz | |
ext4: fix deadlock in journal_unmap_buffer()
We cannot wait for transaction commit in journal_unmap_buffer() because we hold page lock which ranks below transaction start. We solve the issue by bailing out of journal_unmap_buffer() and jbd2_journal_invalidatepage() with -EBUSY. Caller is then responsible for waiting for transaction commit to finish and try invalidation again. Since the issue can happen only for page stradding i_size, it is simple enough to manually call jbd2_journal_invalidatepage() for such page from ext4_setattr(), check the return value and wait if necessary. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/jbd2')
| -rw-r--r-- | fs/jbd2/transaction.c | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index cd4485db42b3..ddc51a7f4508 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -1840,7 +1840,6 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh, BUFFER_TRACE(bh, "entry"); -retry: /* * It is safe to proceed here without the j_list_lock because the * buffers cannot be stolen by try_to_free_buffers as long as we are @@ -1935,14 +1934,11 @@ retry: * for commit and try again. */ if (partial_page) { - tid_t tid = journal->j_committing_transaction->t_tid; - jbd2_journal_put_journal_head(jh); spin_unlock(&journal->j_list_lock); jbd_unlock_bh_state(bh); write_unlock(&journal->j_state_lock); - jbd2_log_wait_commit(journal, tid); - goto retry; + return -EBUSY; } /* * OK, buffer won't be reachable after truncate. We just set @@ -2003,21 +1999,23 @@ zap_buffer_unlocked: * @page: page to flush * @offset: length of page to invalidate. * - * Reap page buffers containing data after offset in page. - * + * Reap page buffers containing data after offset in page. Can return -EBUSY + * if buffers are part of the committing transaction and the page is straddling + * i_size. Caller then has to wait for current commit and try again. */ -void jbd2_journal_invalidatepage(journal_t *journal, - struct page *page, - unsigned long offset) +int jbd2_journal_invalidatepage(journal_t *journal, + struct page *page, + unsigned long offset) { struct buffer_head *head, *bh, *next; unsigned int curr_off = 0; int may_free = 1; + int ret = 0; if (!PageLocked(page)) BUG(); if (!page_has_buffers(page)) - return; + return 0; /* We will potentially be playing with lists other than just the * data lists (especially for journaled data mode), so be @@ -2031,9 +2029,11 @@ void jbd2_journal_invalidatepage(journal_t *journal, if (offset <= curr_off) { /* This block is wholly outside the truncation point */ lock_buffer(bh); - may_free &= journal_unmap_buffer(journal, bh, - offset > 0); + ret = journal_unmap_buffer(journal, bh, offset > 0); unlock_buffer(bh); + if (ret < 0) + return ret; + may_free &= ret; } curr_off = next_off; bh = next; @@ -2044,6 +2044,7 @@ void jbd2_journal_invalidatepage(journal_t *journal, if (may_free && try_to_free_buffers(page)) J_ASSERT(!page_has_buffers(page)); } + return 0; } /* |