xfs: give xfs_rmap_intent its own perag reference

Give the xfs_rmap_intent a passive reference to the perag structure
data.  This reference will be used to enable scrub intent draining
functionality in subsequent patches.  The space we're (reverse) mapping
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, 29 insertions, 3 deletions

diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c
index a1619d67015f..739ddbd04a17 100644
--- a/fs/xfs/xfs_rmap_item.c
+++ b/fs/xfs/xfs_rmap_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_rui_cache;
 struct kmem_cache	*xfs_rud_cache;
@@ -320,14 +321,13 @@ xfs_rmap_update_diff_items(
 	const struct list_head		*a,
 	const struct list_head		*b)
 {
-	struct xfs_mount		*mp = priv;
 	struct xfs_rmap_intent		*ra;
 	struct xfs_rmap_intent		*rb;
 
 	ra = container_of(a, struct xfs_rmap_intent, ri_list);
 	rb = container_of(b, struct xfs_rmap_intent, ri_list);
-	return  XFS_FSB_TO_AGNO(mp, ra->ri_bmap.br_startblock) -
-		XFS_FSB_TO_AGNO(mp, rb->ri_bmap.br_startblock);
+
+	return ra->ri_pag->pag_agno - rb->ri_pag->pag_agno;
 }
 
 /* Log rmap updates in the intent item. */
@@ -390,6 +390,26 @@ xfs_rmap_update_create_done(
 	return &xfs_trans_get_rud(tp, RUI_ITEM(intent))->rud_item;
 }
 
+/* Take a passive ref to the AG containing the space we're rmapping. */
+void
+xfs_rmap_update_get_group(
+	struct xfs_mount	*mp,
+	struct xfs_rmap_intent	*ri)
+{
+	xfs_agnumber_t		agno;
+
+	agno = XFS_FSB_TO_AGNO(mp, ri->ri_bmap.br_startblock);
+	ri->ri_pag = xfs_perag_get(mp, agno);
+}
+
+/* Release a passive AG ref after finishing rmapping work. */
+static inline void
+xfs_rmap_update_put_group(
+	struct xfs_rmap_intent	*ri)
+{
+	xfs_perag_put(ri->ri_pag);
+}
+
 /* Process a deferred rmap update. */
 STATIC int
 xfs_rmap_update_finish_item(
@@ -405,6 +425,8 @@ xfs_rmap_update_finish_item(
 
 	error = xfs_trans_log_finish_rmap_update(tp, RUD_ITEM(done), ri,
 			state);
+
+	xfs_rmap_update_put_group(ri);
 	kmem_cache_free(xfs_rmap_intent_cache, ri);
 	return error;
 }
@@ -425,6 +447,8 @@ xfs_rmap_update_cancel_item(
 	struct xfs_rmap_intent		*ri;
 
 	ri = container_of(item, struct xfs_rmap_intent, ri_list);
+
+	xfs_rmap_update_put_group(ri);
 	kmem_cache_free(xfs_rmap_intent_cache, ri);
 }
 
@@ -559,11 +583,13 @@ xfs_rui_item_recover(
 		fake.ri_bmap.br_state = (map->me_flags & XFS_RMAP_EXTENT_UNWRITTEN) ?
 				XFS_EXT_UNWRITTEN : XFS_EXT_NORM;
 
+		xfs_rmap_update_get_group(mp, &fake);
 		error = xfs_trans_log_finish_rmap_update(tp, rudp, &fake,
 				&rcur);
 		if (error == -EFSCORRUPTED)
 			XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
 					map, sizeof(*map));
+		xfs_rmap_update_put_group(&fake);
 		if (error)
 			goto abort_error;