From 9b2e5a234c89f097ec36f922763dfa1465dc06f8 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Tue, 11 Apr 2023 18:59:55 -0700
Subject: [PATCH] xfs: create traced helper to get extra perag references
There are a few places in the XFS codebase where a caller has either an
active or a passive reference to a perag structure and wants to give
a passive reference to some other piece of code. Btree cursor creation
and inode walks are good examples of this. Replace the open-coded logic
with a helper to do this.
The new function adds a few safeguards -- it checks that there's at
least one reference to the perag structure passed in, and it records the
refcount bump in the ftrace information. This makes it much easier to
debug perag refcounting problems.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/libxfs/xfs_ag.c | 13 +++++++++++++
fs/xfs/libxfs/xfs_ag.h | 1 +
fs/xfs/libxfs/xfs_alloc_btree.c | 4 +---
fs/xfs/libxfs/xfs_ialloc_btree.c | 4 +---
fs/xfs/libxfs/xfs_refcount_btree.c | 5 +----
fs/xfs/libxfs/xfs_rmap_btree.c | 5 +----
fs/xfs/xfs_iunlink_item.c | 4 +---
fs/xfs/xfs_iwalk.c | 5 ++---
fs/xfs/xfs_trace.h | 1 +
9 files changed, 22 insertions(+), 20 deletions(-)
diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index ae45f546ed86f..2d8910046ed95 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -81,6 +81,19 @@ xfs_perag_get_tag(
return pag;
}
+/* Get a passive reference to the given perag. */
+struct xfs_perag *
+xfs_perag_hold(
+ struct xfs_perag *pag)
+{
+ ASSERT(atomic_read(&pag->pag_ref) > 0 ||
+ atomic_read(&pag->pag_active_ref) > 0);
+
+ trace_xfs_perag_hold(pag, _RET_IP_);
+ atomic_inc(&pag->pag_ref);
+ return pag;
+}
+
void
xfs_perag_put(
struct xfs_perag *pag)
diff --git a/fs/xfs/libxfs/xfs_ag.h b/fs/xfs/libxfs/xfs_ag.h
index 5e18536dfdcec..8092eaba977d4 100644
--- a/fs/xfs/libxfs/xfs_ag.h
+++ b/fs/xfs/libxfs/xfs_ag.h
@@ -134,6 +134,7 @@ void xfs_free_perag(struct xfs_mount *mp);
struct xfs_perag *xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno);
struct xfs_perag *xfs_perag_get_tag(struct xfs_mount *mp, xfs_agnumber_t agno,
unsigned int tag);
+struct xfs_perag *xfs_perag_hold(struct xfs_perag *pag);
void xfs_perag_put(struct xfs_perag *pag);
/* Active AG references */
diff --git a/fs/xfs/libxfs/xfs_alloc_btree.c b/fs/xfs/libxfs/xfs_alloc_btree.c
index 0f29c7b1b39f3..8e8416c14cec7 100644
--- a/fs/xfs/libxfs/xfs_alloc_btree.c
+++ b/fs/xfs/libxfs/xfs_alloc_btree.c
@@ -492,9 +492,7 @@ xfs_allocbt_init_common(
cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_abtb_2);
}
- /* take a reference for the cursor */
- atomic_inc(&pag->pag_ref);
- cur->bc_ag.pag = pag;
+ cur->bc_ag.pag = xfs_perag_hold(pag);
if (xfs_has_crc(mp))
cur->bc_flags |= XFS_BTREE_CRC_BLOCKS;
diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
index 1d2af50ac95b0..ad6c521f05ebd 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.c
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
@@ -450,9 +450,7 @@ xfs_inobt_init_common(
if (xfs_has_crc(mp))
cur->bc_flags |= XFS_BTREE_CRC_BLOCKS;
- /* take a reference for the cursor */
- atomic_inc(&pag->pag_ref);
- cur->bc_ag.pag = pag;
+ cur->bc_ag.pag = xfs_perag_hold(pag);
return cur;
}
diff --git a/fs/xfs/libxfs/xfs_refcount_btree.c b/fs/xfs/libxfs/xfs_refcount_btree.c
index 749e837de98d5..03d2b01487a15 100644
--- a/fs/xfs/libxfs/xfs_refcount_btree.c
+++ b/fs/xfs/libxfs/xfs_refcount_btree.c
@@ -340,10 +340,7 @@ xfs_refcountbt_init_common(
cur->bc_flags |= XFS_BTREE_CRC_BLOCKS;
- /* take a reference for the cursor */
- atomic_inc(&pag->pag_ref);
- cur->bc_ag.pag = pag;
-
+ cur->bc_ag.pag = xfs_perag_hold(pag);
cur->bc_ag.refc.nr_ops = 0;
cur->bc_ag.refc.shape_changes = 0;
cur->bc_ops = &xfs_refcountbt_ops;
diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
index d3285684bb5eb..56d074b426609 100644
--- a/fs/xfs/libxfs/xfs_rmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rmap_btree.c
@@ -460,10 +460,7 @@ xfs_rmapbt_init_common(
cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_rmap_2);
cur->bc_ops = &xfs_rmapbt_ops;
- /* take a reference for the cursor */
- atomic_inc(&pag->pag_ref);
- cur->bc_ag.pag = pag;
-
+ cur->bc_ag.pag = xfs_perag_hold(pag);
return cur;
}
diff --git a/fs/xfs/xfs_iunlink_item.c b/fs/xfs/xfs_iunlink_item.c
index 43005ce8bd48a..2ddccb172fa01 100644
--- a/fs/xfs/xfs_iunlink_item.c
+++ b/fs/xfs/xfs_iunlink_item.c
@@ -168,9 +168,7 @@ xfs_iunlink_log_inode(
iup->ip = ip;
iup->next_agino = next_agino;
iup->old_agino = ip->i_next_unlinked;
-
- atomic_inc(&pag->pag_ref);
- iup->pag = pag;
+ iup->pag = xfs_perag_hold(pag);
xfs_trans_add_item(tp, &iup->item);
tp->t_flags |= XFS_TRANS_DIRTY;
diff --git a/fs/xfs/xfs_iwalk.c b/fs/xfs/xfs_iwalk.c
index 21be93bf006dd..b3275e8d47b60 100644
--- a/fs/xfs/xfs_iwalk.c
+++ b/fs/xfs/xfs_iwalk.c
@@ -667,11 +667,10 @@ xfs_iwalk_threaded(
iwag->mp = mp;
/*
- * perag is being handed off to async work, so take another
+ * perag is being handed off to async work, so take a passive
* reference for the async work to release.
*/
- atomic_inc(&pag->pag_ref);
- iwag->pag = pag;
+ iwag->pag = xfs_perag_hold(pag);
iwag->iwalk_fn = iwalk_fn;
iwag->data = data;
iwag->startino = startino;
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 9c0006c55fec3..db09bb7717658 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -190,6 +190,7 @@ DEFINE_EVENT(xfs_perag_class, name, \
TP_ARGS(pag, caller_ip))
DEFINE_PERAG_REF_EVENT(xfs_perag_get);
DEFINE_PERAG_REF_EVENT(xfs_perag_get_tag);
+DEFINE_PERAG_REF_EVENT(xfs_perag_hold);
DEFINE_PERAG_REF_EVENT(xfs_perag_put);
DEFINE_PERAG_REF_EVENT(xfs_perag_grab);
DEFINE_PERAG_REF_EVENT(xfs_perag_grab_tag);
--
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