dax: set errors in mapping when writeback fails

Jan Kara's description for this patch is much better than mine, so I'm
quoting it verbatim here:

DAX currently doesn't set errors in the mapping when cache flushing
fails in dax_writeback_mapping_range(). Since this function can get
called only from fsync(2) or sync(2), this is actually as good as it can
currently get since we correctly propagate the error up from
dax_writeback_mapping_range() to filemap_fdatawrite()

However, in the future better writeback error handling will enable us to
properly report these errors on fsync(2) even if there are multiple file
descriptors open against the file or if sync(2) gets called before
fsync(2). So convert DAX to using standard error reporting through the
mapping.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-and-tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>

diff --git a/fs/dax.c b/fs/dax.c
index c22eaf162f95c1456563b31a8362da9e531c9185..441280e15d5b8ee101f60cdc747a617d944bcecd 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -856,8 +856,10 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 
                        ret = dax_writeback_one(bdev, dax_dev, mapping,
                                        indices[i], pvec.pages[i]);
-                       if (ret < 0)
+                       if (ret < 0) {
+                               mapping_set_error(mapping, ret);
                                goto out;
+                       }
                }
        }
 out: