quota: Fix error codes in v2_read_file_info()

v2_read_file_info() returned -1 instead of proper error codes on error.
Luckily this is not easily visible from userspace as we have called
->check_quota_file shortly before and thus already verified the quota
file is sane. Still set the error codes to proper values.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/quota_v2.c

@@ -99,13 +99,13 @@ static int v2_read_file_info(struct super_block *sb, int type)
 
 	down_read(&dqopt->dqio_sem);
 	if (!v2_read_header(sb, type, &dqhead)) {
-		ret = -1;
+		ret = -EIO;
 		goto out;
 	}
 	version = le32_to_cpu(dqhead.dqh_version);
 	if ((info->dqi_fmt_id == QFMT_VFS_V0 && version != 0) ||
 	    (info->dqi_fmt_id == QFMT_VFS_V1 && version != 1)) {
-		ret = -1;
+		ret = -EINVAL;
 		goto out;
 	}
 
@@ -113,7 +113,7 @@ static int v2_read_file_info(struct super_block *sb, int type)
 	       sizeof(struct v2_disk_dqinfo), V2_DQINFOOFF);
 	if (size != sizeof(struct v2_disk_dqinfo)) {
 		quota_error(sb, "Can't read info structure");
-		ret = -1;
+		ret = -EIO;
 		goto out;
 	}
 	info->dqi_priv = kmalloc(sizeof(struct qtree_mem_dqinfo), GFP_NOFS);