linux-kernel - [PATCH] btrfs: Fix the return value in case of error in 'btrfs_mark_extent

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Message-Id: <20181017091359.3763-1-christophe.jaillet@wanadoo.fr>
Date:   Wed, 17 Oct 2018 11:13:59 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     clm@...com, jbacik@...com, dsterba@...e.com
Cc:     linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] btrfs: Fix the return value in case of error in 'btrfs_mark_extent_written()'

We return 0 unconditionally in most of the error handling paths of
'btrfs_mark_extent_written()'.
However, 'ret' is set to some error codes in several error handling paths.

Return 'ret' instead to propagate the error code.

Fixes: 9c8e63db1de9 ("Btrfs: kill BUG_ON()'s in btrfs_mark_extent_written")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
This patch proposal is purely speculative.
I'm not sure at all that returning 'ret' is correct (but it looks like it
is :) )

What puzzles me is when 'ret' is set, 'btrfs_abort_transaction()' is also
called.
However, the only caller of 'btrfs_mark_extent_written()' (i.e.
'btrfs_finish_ordered_io()') also calls 'btrfs_abort_transaction()' if an
error is returned.
So returning an error code here, would lead to a double call to this abort
function.

I'm usure of if it is correct and/or intented.
If returning 'ret' is correct, should we also axe the 'btrfs_abort_transaction()'
calls here, and leave the caller do the clean-up?

Before the commit in the Fixes tag, we were BUGing_ON in case of errror. So
propagating the error was pointless.
---
 fs/btrfs/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 15b925142793..cac0bd744de3 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1374,7 +1374,7 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 	}
 out:
 	btrfs_free_path(path);
-	return 0;
+	return ret;
 }

 /*
-- 
2.17.1