4.19-stable review patch. If anyone has any objections, please let me know.
------------------ From: Matthew Wilcox <[email protected]> commit c93db7bb6ef3251e0ea48ade311d3e9942748e1c upstream. If we race with inode destroy, it's possible for page->mapping to be NULL before we even enter this routine, as well as after having slept waiting for the dax entry to become unlocked. Fixes: c2a7d2a11552 ("filesystem-dax: Introduce dax_lock_mapping_entry()") Cc: <[email protected]> Reported-by: Jan Kara <[email protected]> Signed-off-by: Matthew Wilcox <[email protected]> Reviewed-by: Johannes Thumshirn <[email protected]> Reviewed-by: Jan Kara <[email protected]> Signed-off-by: Dan Williams <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/dax.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/dax.c +++ b/fs/dax.c @@ -423,7 +423,7 @@ bool dax_lock_mapping_entry(struct page for (;;) { mapping = READ_ONCE(page->mapping); - if (!dax_mapping(mapping)) + if (!mapping || !dax_mapping(mapping)) break; /*
