[PATCH] xfs: Check for m_errortag initialization in xfs_errortag_test

[PATCH] xfs: Check for m_errortag initialization in xfs_errortag_test

[Carlos Maiolino]

While adding error injection into IO completion, I notice the lack of
initialization check in xfs_errortag_test(), make the error injection
mechanism unable to be used there.

IO completion is executed a few times before the error injection
mechanism is initialized, so to be safer, make xfs_errortag_test() check
if the errortag is properly initialized.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
---
 fs/xfs/xfs_error.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c
index 26c32bc..2f4feb9 100644
--- a/fs/xfs/xfs_error.c
+++ b/fs/xfs/xfs_error.c
@@ -233,6 +233,17 @@ xfs_errortag_test(
 {
 	unsigned int		randfactor;
 
+	/*
+	 * To be able to use error injection anywhere, we need to ensure error
+	 * injection mechanism is already initialized.
+	 *
+	 * Code paths like I/O completion can be called before the
+	 * initialization is complete, but be able to inject errors in such
+	 * places is still useful.
+	 */
+	if (!mp->m_errortag)
+		return false;
+
 	ASSERT(error_tag < XFS_ERRTAG_MAX);
 	randfactor = mp->m_errortag[error_tag];
 	if (!randfactor || prandom_u32() % randfactor)
-- 
2.9.4

Re: [PATCH] xfs: Check for m_errortag initialization in xfs_errortag_test

[Darrick J. Wong]

On Fri, Jun 30, 2017 at 03:03:01PM +0200, Carlos Maiolino wrote:
> While adding error injection into IO completion, I notice the lack of
> initialization check in xfs_errortag_test(), make the error injection
> mechanism unable to be used there.
> 
> IO completion is executed a few times before the error injection
> mechanism is initialized, so to be safer, make xfs_errortag_test() check
> if the errortag is properly initialized.
> 
> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>

Ahah, hadn't realized that.  Looks good,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  fs/xfs/xfs_error.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c
> index 26c32bc..2f4feb9 100644
> --- a/fs/xfs/xfs_error.c
> +++ b/fs/xfs/xfs_error.c
> @@ -233,6 +233,17 @@ xfs_errortag_test(
>  {
>  	unsigned int		randfactor;
>  
> +	/*
> +	 * To be able to use error injection anywhere, we need to ensure error
> +	 * injection mechanism is already initialized.
> +	 *
> +	 * Code paths like I/O completion can be called before the
> +	 * initialization is complete, but be able to inject errors in such
> +	 * places is still useful.
> +	 */
> +	if (!mp->m_errortag)
> +		return false;
> +
>  	ASSERT(error_tag < XFS_ERRTAG_MAX);
>  	randfactor = mp->m_errortag[error_tag];
>  	if (!randfactor || prandom_u32() % randfactor)
> -- 
> 2.9.4
> 
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