xfs: Check for m_errortag initialization in xfs_errortag_test

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>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c
index 26c32bc5cd34..2f4feb959bfb 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)