ext2: fix ignored return value of generic_write_sync()

In the Linux kernel, the following vulnerability has been resolved: ext2: fix ignored return value of generic_write_sync() Fix ext2_dio_write_iter() to propagate the error returned by generic_write_sync() instead of silently discarding it, which could cause write(2) to return success to userspace on O_SYNC/O_DSYNC files even when the sync failed. The correct pattern, already used in ext2_dax_write_iter() in the same file and in ext4, xfs, f2fs among others, is: if (ret > 0) ret = generic_write_sync(iocb, ret); Found by Linux Verification Center (linuxtesting.org) with SVACE. [JK: Reflect also filemap_write_and_wait() return value]