4 files changed, 23 insertions, 5 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 2f97c12ca75e..d481dd2b29a6 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -42,6 +42,7 @@
 #include "xfs_mount.h"
 #include "xfs_trace.h"
 #include "xfs_log.h"
+#include "xfs_error.h"
 
 static kmem_zone_t *xfs_buf_zone;
 
@@ -2129,3 +2130,18 @@ xfs_buf_terminate(void)
 {
 	kmem_zone_destroy(xfs_buf_zone);
 }
+
+void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
+{
+	struct xfs_mount	*mp = bp->b_target->bt_mount;
+
+	/*
+	 * Set the lru reference count to 0 based on the error injection tag.
+	 * This allows userspace to disrupt buffer caching for debug/testing
+	 * purposes.
+	 */
+	if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_BUF_LRU_REF))
+		lru_ref = 0;
+
+	atomic_set(&bp->b_lru_ref, lru_ref);
+}
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index bf71507ddb16..f873bb786824 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -352,10 +352,7 @@ extern void xfs_buf_terminate(void);
 #define XFS_BUF_ADDR(bp)		((bp)->b_maps[0].bm_bn)
 #define XFS_BUF_SET_ADDR(bp, bno)	((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))
 
-static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
-{
-	atomic_set(&bp->b_lru_ref, lru_ref);
-}
+void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref);
 
 static inline int xfs_buf_ispinned(struct xfs_buf *bp)
 {
diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c
index eaf86f55b7f2..6732b0a0d826 100644
--- a/fs/xfs/xfs_error.c
+++ b/fs/xfs/xfs_error.c
@@ -58,6 +58,7 @@ static unsigned int xfs_errortag_random_default[] = {
 	XFS_RANDOM_DROP_WRITES,
 	XFS_RANDOM_LOG_BAD_CRC,
 	XFS_RANDOM_LOG_ITEM_PIN,
+	XFS_RANDOM_BUF_LRU_REF,
 };
 
 struct xfs_errortag_attr {
@@ -163,6 +164,7 @@ XFS_ERRORTAG_ATTR_RW(ag_resv_critical,	XFS_ERRTAG_AG_RESV_CRITICAL);
 XFS_ERRORTAG_ATTR_RW(drop_writes,	XFS_ERRTAG_DROP_WRITES);
 XFS_ERRORTAG_ATTR_RW(log_bad_crc,	XFS_ERRTAG_LOG_BAD_CRC);
 XFS_ERRORTAG_ATTR_RW(log_item_pin,	XFS_ERRTAG_LOG_ITEM_PIN);
+XFS_ERRORTAG_ATTR_RW(buf_lru_ref,	XFS_ERRTAG_BUF_LRU_REF);
 
 static struct attribute *xfs_errortag_attrs[] = {
 	XFS_ERRORTAG_ATTR_LIST(noerror),
@@ -196,6 +198,7 @@ static struct attribute *xfs_errortag_attrs[] = {
 	XFS_ERRORTAG_ATTR_LIST(drop_writes),
 	XFS_ERRORTAG_ATTR_LIST(log_bad_crc),
 	XFS_ERRORTAG_ATTR_LIST(log_item_pin),
+	XFS_ERRORTAG_ATTR_LIST(buf_lru_ref),
 	NULL,
 };
 
diff --git a/fs/xfs/xfs_error.h b/fs/xfs/xfs_error.h
index 7c4bef3bddb7..78a7f43f8d01 100644
--- a/fs/xfs/xfs_error.h
+++ b/fs/xfs/xfs_error.h
@@ -107,7 +107,8 @@ extern void xfs_verifier_error(struct xfs_buf *bp);
 #define XFS_ERRTAG_DROP_WRITES				28
 #define XFS_ERRTAG_LOG_BAD_CRC				29
 #define XFS_ERRTAG_LOG_ITEM_PIN				30
-#define XFS_ERRTAG_MAX					31
+#define XFS_ERRTAG_BUF_LRU_REF				31
+#define XFS_ERRTAG_MAX					32
 
 /*
  * Random factors for above tags, 1 means always, 2 means 1/2 time, etc.
@@ -143,6 +144,7 @@ extern void xfs_verifier_error(struct xfs_buf *bp);
 #define XFS_RANDOM_DROP_WRITES				1
 #define XFS_RANDOM_LOG_BAD_CRC				1
 #define XFS_RANDOM_LOG_ITEM_PIN				1
+#define XFS_RANDOM_BUF_LRU_REF				2
 
 #ifdef DEBUG
 extern int xfs_errortag_init(struct xfs_mount *mp);