Hello Trond Myklebust,
Commit 6c984083ec24 ("NFS: Use of mapping_set_error() results in
spurious errors") from Feb 15, 2022 (linux-next), leads to the
following Smatch static checker warning:
fs/nfs/write.c:318 nfs_mapping_set_error()
error: we previously assumed 'mapping->host' could be null (see line 315)
fs/nfs/write.c
310 static void nfs_mapping_set_error(struct folio *folio, int error)
311 {
312 struct address_space *mapping = folio_file_mapping(folio);
313
314 filemap_set_wb_err(mapping, error);
315 if (mapping->host)
^^^^^^^^^^^^^
The patch adds a check
316 errseq_set(&mapping->host->i_sb->s_wb_err,
317 error == -ENOSPC ? -ENOSPC : -EIO);
--> 318 nfs_set_pageerror(mapping);
^^^^^^^
But the next line dereferences mapping->host without checking.
319 }
regards,
dan carpenter
