[PATCH v5 5/5] xfs: add error injection for per-AG resv failure when shrinkfs

[Gao Xiang <hsiangkao@xxxxxxxxxx>]

per-AG resv failure after fixing up freespace is hard to test in an
effective way, so directly add an error injection path to observe
such error handling path works as expected.

Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
---
 fs/xfs/libxfs/xfs_ag.c       | 5 +++++
 fs/xfs/libxfs/xfs_errortag.h | 2 ++
 fs/xfs/xfs_error.c           | 2 ++
 3 files changed, 9 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index 04a7c9b20470..65e8e07f179b 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -23,6 +23,7 @@
 #include "xfs_ag_resv.h"
 #include "xfs_health.h"
 #include "xfs_error.h"
+#include "xfs_errortag.h"
 #include "xfs_bmap.h"
 
 static int
@@ -552,6 +553,10 @@ xfs_ag_shrink_space(
 	be32_add_cpu(&agf->agf_length, -len);
 
 	err2 = xfs_ag_resv_init(agibp->b_pag, tp);
+
+	if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_SHRINKFS_AG_RESV_FAIL))
+		err2 = -ENOSPC;
+
 	if (err2) {
 		be32_add_cpu(&agi->agi_length, len);
 		be32_add_cpu(&agf->agf_length, len);
diff --git a/fs/xfs/libxfs/xfs_errortag.h b/fs/xfs/libxfs/xfs_errortag.h
index 53b305dea381..89da08a451cf 100644
--- a/fs/xfs/libxfs/xfs_errortag.h
+++ b/fs/xfs/libxfs/xfs_errortag.h
@@ -40,6 +40,8 @@
 #define XFS_ERRTAG_REFCOUNT_FINISH_ONE			25
 #define XFS_ERRTAG_BMAP_FINISH_ONE			26
 #define XFS_ERRTAG_AG_RESV_CRITICAL			27
+#define XFS_ERRTAG_SHRINKFS_AG_RESV_FAIL		28
+
 /*
  * DEBUG mode instrumentation to test and/or trigger delayed allocation
  * block killing in the event of failed writes. When enabled, all
diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c
index 7f6e20899473..c864451ba7d0 100644
--- a/fs/xfs/xfs_error.c
+++ b/fs/xfs/xfs_error.c
@@ -164,6 +164,7 @@ XFS_ERRORTAG_ATTR_RW(force_repair,	XFS_ERRTAG_FORCE_SCRUB_REPAIR);
 XFS_ERRORTAG_ATTR_RW(bad_summary,	XFS_ERRTAG_FORCE_SUMMARY_RECALC);
 XFS_ERRORTAG_ATTR_RW(iunlink_fallback,	XFS_ERRTAG_IUNLINK_FALLBACK);
 XFS_ERRORTAG_ATTR_RW(buf_ioerror,	XFS_ERRTAG_BUF_IOERROR);
+XFS_ERRORTAG_ATTR_RW(shrinkfs_ag_resv_fail, XFS_ERRTAG_SHRINKFS_AG_RESV_FAIL);
 
 static struct attribute *xfs_errortag_attrs[] = {
 	XFS_ERRORTAG_ATTR_LIST(noerror),
@@ -202,6 +203,7 @@ static struct attribute *xfs_errortag_attrs[] = {
 	XFS_ERRORTAG_ATTR_LIST(bad_summary),
 	XFS_ERRORTAG_ATTR_LIST(iunlink_fallback),
 	XFS_ERRORTAG_ATTR_LIST(buf_ioerror),
+	XFS_ERRORTAG_ATTR_LIST(shrinkfs_ag_resv_fail),
 	NULL,
 };
 
-- 
2.27.0