xfs: give xfs_refcount_intent its own perag reference

Give the xfs_refcount_intent a passive reference to the perag structure
data.  This reference will be used to enable scrub intent draining
functionality in subsequent patches.  Any space being modified by a
refcount intent is already allocated, so we need to be able to operate
even if the AG is being shrunk or offlined.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

1 files changed, 32 insertions, 4 deletions

diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c
index 48d771a76add..7edee9590ed6 100644
--- a/fs/xfs/xfs_refcount_item.c
+++ b/fs/xfs/xfs_refcount_item.c
@@ -20,6 +20,7 @@
 #include "xfs_error.h"
 #include "xfs_log_priv.h"
 #include "xfs_log_recover.h"
+#include "xfs_ag.h"
 
 struct kmem_cache	*xfs_cui_cache;
 struct kmem_cache	*xfs_cud_cache;
@@ -279,14 +280,13 @@ xfs_refcount_update_diff_items(
 	const struct list_head		*a,
 	const struct list_head		*b)
 {
-	struct xfs_mount		*mp = priv;
 	struct xfs_refcount_intent	*ra;
 	struct xfs_refcount_intent	*rb;
 
 	ra = container_of(a, struct xfs_refcount_intent, ri_list);
 	rb = container_of(b, struct xfs_refcount_intent, ri_list);
-	return  XFS_FSB_TO_AGNO(mp, ra->ri_startblock) -
-		XFS_FSB_TO_AGNO(mp, rb->ri_startblock);
+
+	return ra->ri_pag->pag_agno - rb->ri_pag->pag_agno;
 }
 
 /* Set the phys extent flags for this reverse mapping. */
@@ -365,6 +365,26 @@ xfs_refcount_update_create_done(
 	return &xfs_trans_get_cud(tp, CUI_ITEM(intent))->cud_item;
 }
 
+/* Take a passive ref to the AG containing the space we're refcounting. */
+void
+xfs_refcount_update_get_group(
+	struct xfs_mount		*mp,
+	struct xfs_refcount_intent	*ri)
+{
+	xfs_agnumber_t			agno;
+
+	agno = XFS_FSB_TO_AGNO(mp, ri->ri_startblock);
+	ri->ri_pag = xfs_perag_get(mp, agno);
+}
+
+/* Release a passive AG ref after finishing refcounting work. */
+static inline void
+xfs_refcount_update_put_group(
+	struct xfs_refcount_intent	*ri)
+{
+	xfs_perag_put(ri->ri_pag);
+}
+
 /* Process a deferred refcount update. */
 STATIC int
 xfs_refcount_update_finish_item(
@@ -386,6 +406,8 @@ xfs_refcount_update_finish_item(
 		       ri->ri_type == XFS_REFCOUNT_DECREASE);
 		return -EAGAIN;
 	}
+
+	xfs_refcount_update_put_group(ri);
 	kmem_cache_free(xfs_refcount_intent_cache, ri);
 	return error;
 }
@@ -406,6 +428,8 @@ xfs_refcount_update_cancel_item(
 	struct xfs_refcount_intent	*ri;
 
 	ri = container_of(item, struct xfs_refcount_intent, ri_list);
+
+	xfs_refcount_update_put_group(ri);
 	kmem_cache_free(xfs_refcount_intent_cache, ri);
 }
 
@@ -520,9 +544,13 @@ xfs_cui_item_recover(
 
 		fake.ri_startblock = pmap->pe_startblock;
 		fake.ri_blockcount = pmap->pe_len;
-		if (!requeue_only)
+
+		if (!requeue_only) {
+			xfs_refcount_update_get_group(mp, &fake);
 			error = xfs_trans_log_finish_refcount_update(tp, cudp,
 					&fake, &rcur);
+			xfs_refcount_update_put_group(&fake);
+		}
 		if (error == -EFSCORRUPTED)
 			XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
 					&cuip->cui_format,