linux-ext4 - Re: [PATCH] ext4: BUG_ON assertion repeated for inode1, not done for inode2

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Date:	Tue, 26 May 2015 15:44:24 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	David Moore <dmoorefo@...il.com>, tytso@....edu
CC:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: BUG_ON assertion repeated for inode1, not done
 for inode2

On 5/26/15 12:42 PM, David Moore wrote:
> During a source code review of fs/ext4/extents.c I noted identical
> consecutive lines. An assertion is repeated for inode1 and never done
> for inode2. This is not in keeping with the rest of the code in the
> ext4_swap_extents function and appears to be a bug.
> 
> Assert that the inode2 mutex is not locked.

Yep, it's been that way since 

fcf6b1b ext4: refactor ext4_move_extents code base

and it's pretty obviously not right as it is, and
if there's any doubt the comments make it clear:

+ * Locking:
+ *             i_mutex is held for both inodes
+ *             i_data_sem is locked for write for both inodes

Thanks,

Reviewed-by: Eric Sandeen <sandeen@...hat.com>

> Signed-off-by: David Moore <dmoorefo@...il.com>
> ---
>  fs/ext4/extents.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index e003a1e..f38a6d6 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -5542,7 +5542,7 @@ ext4_swap_extents(handle_t *handle, struct inode *inode1,
> BUG_ON(!rwsem_is_locked(&EXT4_I(inode1)->i_data_sem));
> BUG_ON(!rwsem_is_locked(&EXT4_I(inode2)->i_data_sem));
>         BUG_ON(!mutex_is_locked(&inode1->i_mutex));
> -       BUG_ON(!mutex_is_locked(&inode1->i_mutex));
> +       BUG_ON(!mutex_is_locked(&inode2->i_mutex));
> 
>         *erp = ext4_es_remove_extent(inode1, lblk1, count);
>         if (unlikely(*erp))
> 
> -- 
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