From bd159398a2d2234de07d310132865706964aaaa7 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Wed, 29 Mar 2023 17:49:32 +0200
Subject: [PATCH] jdb2: Don't refuse invalidation of already invalidated
 buffers
Git-commit: bd159398a2d2234de07d310132865706964aaaa7
Patch-mainline: v6.4-rc1
References: bsc#1213014

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>
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/jbd2/transaction.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -2269,6 +2269,9 @@ static int journal_unmap_buffer(journal_
 			spin_unlock(&journal->j_list_lock);
 			jbd_unlock_bh_state(bh);
 			write_unlock(&journal->j_state_lock);
+			/* Already zapped buffer? Nothing to do... */
+			if (!bh->b_bdev)
+				return 0;
 			return -EBUSY;
 		}
 		/*