jdb2: Don't refuse invalidation of already invalidated buffers

When invalidating buffers under the partial tail page,
jbd2_journal_invalidate_folio() returns -EBUSY if the buffer is part of
the committing transaction as we cannot safely modify buffer state.
However if the buffer is already invalidated (due to previous
invalidation attempts from ext4_wait_for_tail_page_commit()), there's
nothing to do and there's no point in returning -EBUSY. This fixes
occasional warnings from ext4_journalled_invalidate_folio() triggered by
generic/051 fstest when blocksize < pagesize.

Fixes: 53e872681fed ("ext4: fix deadlock in journal_unmap_buffer()")
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 15de1385012eb4c6de0b6886d5029858b0f50684..18611241f4513168989210e6c767dc31eb26c3ea 100644 (file)
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -2387,6 +2387,9 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
                        spin_unlock(&jh->b_state_lock);
                        write_unlock(&journal->j_state_lock);
                        jbd2_journal_put_journal_head(jh);
+                       /* Already zapped buffer? Nothing to do... */
+                       if (!bh->b_bdev)
+                               return 0;
                        return -EBUSY;
                }
                /*