mm: have filemap_check_and_advance_wb_err clear AS_EIO/AS_ENOSPC

Eryu noticed that he could sometimes get a leftover error reported when
it shouldn't be on fsync with ext2 and non-journalled ext4.

The problem is that writeback_single_inode still uses filemap_fdatawait.
That picks up a previously set AS_EIO flag, which would ordinarily have
been cleared before.

Since we're mostly using this function as a replacement for
filemap_check_errors, have filemap_check_and_advance_wb_err clear AS_EIO
and AS_ENOSPC when reporting an error.  That should allow the new
function to better emulate the behavior of the old with respect to these
flags.

Link: http://lkml.kernel.org/r/20170922133331.28812-1-jlayton@kernel.org
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reported-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index db250d0e05655a2e4b72e4f7a7834964a641c86d..594d73fef8b43bae852f4f7ace1e8cfc46b23690 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -620,6 +620,14 @@ int file_check_and_advance_wb_err(struct file *file)
                trace_file_check_and_advance_wb_err(file, old);
                spin_unlock(&file->f_lock);
        }
+
+       /*
+        * We're mostly using this function as a drop in replacement for
+        * filemap_check_errors. Clear AS_EIO/AS_ENOSPC to emulate the effect
+        * that the legacy code would have had on these flags.
+        */
+       clear_bit(AS_EIO, &mapping->flags);
+       clear_bit(AS_ENOSPC, &mapping->flags);
        return err;
 }
 EXPORT_SYMBOL(file_check_and_advance_wb_err);