xfs: allocate m_errortag early

Ensure the mount structure always has a valid m_errortag for debug
builds.  This removes the NULL checking from the runtime code, and
prepares for allowing to set errortags from mount.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: Christoph Hellwig

fs/xfs/xfs_error.c

@@ -114,26 +114,15 @@ int
 xfs_errortag_init(
 	struct xfs_mount	*mp)
 {
-	int ret;
-
-	mp->m_errortag = kzalloc(sizeof(unsigned int) * XFS_ERRTAG_MAX,
-				GFP_KERNEL | __GFP_RETRY_MAYFAIL);
-	if (!mp->m_errortag)
-		return -ENOMEM;
-
-	ret = xfs_sysfs_init(&mp->m_errortag_kobj, &xfs_errortag_ktype,
+	return xfs_sysfs_init(&mp->m_errortag_kobj, &xfs_errortag_ktype,
 				&mp->m_kobj, "errortag");
-	if (ret)
-		kfree(mp->m_errortag);
-	return ret;
 }
 
 void
 xfs_errortag_del(
 	struct xfs_mount	*mp)
 {
 	xfs_sysfs_del(&mp->m_errortag_kobj);
-	kfree(mp->m_errortag);
 }
 
 static bool
@@ -154,8 +143,6 @@ xfs_errortag_enabled(
 	struct xfs_mount	*mp,
 	unsigned int		tag)
 {
-	if (!mp->m_errortag)
-		return false;
 	if (!xfs_errortag_valid(tag))
 		return false;
 
@@ -171,17 +158,6 @@ 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;
-
 	if (!xfs_errortag_valid(error_tag))
 		return false;
 

fs/xfs/xfs_super.c

@@ -40,6 +40,7 @@
 #include "xfs_defer.h"
 #include "xfs_attr_item.h"
 #include "xfs_xattr.h"
+#include "xfs_errortag.h"
 #include "xfs_iunlink_item.h"
 #include "xfs_dahash_test.h"
 #include "xfs_rtbitmap.h"
@@ -824,6 +825,9 @@ xfs_mount_free(
 	debugfs_remove(mp->m_debugfs);
 	kfree(mp->m_rtname);
 	kfree(mp->m_logname);
+#ifdef DEBUG
+	kfree(mp->m_errortag);
+#endif
 	kfree(mp);
 }
 
@@ -2266,6 +2270,14 @@ xfs_init_fs_context(
 	mp = kzalloc(sizeof(struct xfs_mount), GFP_KERNEL);
 	if (!mp)
 		return -ENOMEM;
+#ifdef DEBUG
+	mp->m_errortag = kcalloc(XFS_ERRTAG_MAX, sizeof(*mp->m_errortag),
+			GFP_KERNEL);
+	if (!mp->m_errortag) {
+		kfree(mp);
+		return -ENOMEM;
+	}
+#endif
 
 	spin_lock_init(&mp->m_sb_lock);
 	for (i = 0; i < XG_TYPE_MAX; i++)