2015-05-26 17:42:14

by David Moore

Subject: [PATCH] ext4: BUG_ON assertion repeated for inode1, not done for inode2

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.

Signed-off-by: David Moore <[email protected]>
---
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))

2015-05-26 20:44:38

by Eric Sandeen

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 <[email protected]>

> Signed-off-by: David Moore <[email protected]>
> ---
> 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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2015-06-08 15:59:40

by Theodore Ts'o

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

On Tue, May 26, 2015 at 03:44:24PM -0500, Eric Sandeen wrote:
> 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 <[email protected]>

Thanks, applied.

- Ted