From: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Date: Tue, 8 Sep 2026 01:37:12 +0000 (-0400)
Subject: wip: cand28 = cand25 + extent-buffer leak forensics (audit search present)
X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bb3b4e80ea8e20a96e955913b71bb465958e701e;p=linux

wip: cand28 = cand25 + extent-buffer leak forensics (audit search present)
---

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 6c251d78a7506..003d9beaaf4ba 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -580,9 +580,19 @@ struct extent_buffer *btrfs_find_create_tree_block(
 						u64 bytenr, u64 owner_root,
 						int level)
 {
+	struct extent_buffer *eb;
+
 	if (btrfs_is_testing(fs_info))
 		return alloc_test_extent_buffer(fs_info, bytenr);
-	return alloc_extent_buffer(fs_info, bytenr, owner_root, level);
+	eb = alloc_extent_buffer(fs_info, bytenr, owner_root, level);
+#ifdef CONFIG_BTRFS_DEBUG
+	if (!IS_ERR(eb)) {
+		if (!eb->dbg_create_ip)
+			eb->dbg_create_ip = _RET_IP_;
+		btrfs_eb_dbg_grab(eb, _RET_IP_);
+	}
+#endif
+	return eb;
 }
 
 /*
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 2c2218ff00adb..b76515b1acaf4 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -76,9 +76,18 @@ void btrfs_extent_buffer_leak_debug_check(struct btrfs_fs_info *fs_info)
 		eb = list_first_entry(&fs_info->allocated_ebs,
 				      struct extent_buffer, leak_list);
 		btrfs_err(fs_info,
-		       "buffer leak start %llu len %u refs %d bflags %lu owner %llu",
+"buffer leak start %llu len %u refs %d bflags %lu owner %llu gen %llu level %d nritems %u log_index %d lock_owner %d f0up %d",
 		       eb->start, eb->len, refcount_read(&eb->refs), eb->bflags,
-		       btrfs_header_owner(eb));
+		       btrfs_header_owner(eb), btrfs_header_generation(eb),
+		       btrfs_header_level(eb), btrfs_header_nritems(eb),
+		       eb->log_index, eb->lock_owner,
+		       eb->folios[0] ? folio_test_uptodate(eb->folios[0]) : -1);
+		btrfs_err(fs_info, "  leak: created %pS staled %pS grabs %u",
+			  (void *)eb->dbg_create_ip, (void *)eb->dbg_stale_ip,
+			  eb->dbg_grab_n);
+		for (int i = 0; i < 6; i++)
+			btrfs_err(fs_info, "  leak: grab[%d] %pS", i,
+				  (void *)eb->dbg_grab_ip[i]);
 		list_del(&eb->leak_list);
 		WARN_ON_ONCE(1);
 		kmem_cache_free(extent_buffer_cache, eb);
@@ -3202,6 +3211,7 @@ struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
 		spin_lock(&eb->refs_lock);
 		spin_unlock(&eb->refs_lock);
 	}
+	btrfs_eb_dbg_grab(eb, _RET_IP_);
 	mark_extent_buffer_accessed(eb);
 	return eb;
 }
@@ -3703,6 +3713,9 @@ void free_extent_buffer_stale(struct extent_buffer *eb)
 
 	spin_lock(&eb->refs_lock);
 	set_bit(EXTENT_BUFFER_STALE, &eb->bflags);
+#ifdef CONFIG_BTRFS_DEBUG
+	eb->dbg_stale_ip = _RET_IP_;
+#endif
 
 	if (refcount_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) &&
 	    test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 73571d5d3d5ad..c8ba72f8ee5b1 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -115,9 +115,23 @@ struct extent_buffer {
 #ifdef CONFIG_BTRFS_DEBUG
 	struct list_head leak_list;
 	pid_t lock_owner;
+	/* DEBUG (cand27): where the last refs were taken / the block staled */
+	unsigned long dbg_grab_ip[6];
+	unsigned int dbg_grab_n;
+	unsigned long dbg_create_ip;
+	unsigned long dbg_stale_ip;
 #endif
 };
 
+#ifdef CONFIG_BTRFS_DEBUG
+static inline void btrfs_eb_dbg_grab(struct extent_buffer *eb, unsigned long ip)
+{
+	eb->dbg_grab_ip[eb->dbg_grab_n++ % 6] = ip;
+}
+#else
+#define btrfs_eb_dbg_grab(eb, ip)	do {} while (0)
+#endif
+
 struct btrfs_eb_write_context {
 	struct writeback_control *wbc;
 	struct extent_buffer *eb;