add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/include/trace/events/writeback.h
..
..
@@ -67,7 +67,7 @@
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 		strscpy_pad(__entry->name,
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 			    bdi_dev_name(mapping ? inode_to_bdi(mapping->host) :
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 					 NULL), 32);
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-		__entry->ino = mapping ? mapping->host->i_ino : 0;
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+		__entry->ino = (mapping && mapping->host) ? mapping->host->i_ino : 0;
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 		__entry->index = page->index;
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 	),
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