gfs2: Minor gfs2_lookup_by_inum cleanup

Use a zero no_formal_ino instead of a NULL pointer to indicate that any inode
generation number will qualify: a valid inode never has a zero no_formal_ino.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/export.c

@@ -134,7 +134,9 @@ static struct dentry *gfs2_get_dentry(struct super_block *sb,
 	struct gfs2_sbd *sdp = sb->s_fs_info;
 	struct inode *inode;
 
-	inode = gfs2_lookup_by_inum(sdp, inum->no_addr, &inum->no_formal_ino,
+	if (!inum->no_formal_ino)
+		return ERR_PTR(-ESTALE);
+	inode = gfs2_lookup_by_inum(sdp, inum->no_addr, inum->no_formal_ino,
 				    GFS2_BLKST_DINODE);
 	if (IS_ERR(inode))
 		return ERR_CAST(inode);

fs/gfs2/glock.c

@@ -843,7 +843,7 @@ static void delete_work_func(struct work_struct *work)
 		}
 	}
 
-	inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
+	inode = gfs2_lookup_by_inum(sdp, no_addr, 0, GFS2_BLKST_UNLINKED);
 	if (!IS_ERR_OR_NULL(inode)) {
 		d_prune_aliases(inode);
 		iput(inode);

fs/gfs2/inode.c

@@ -207,8 +207,15 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 	return ERR_PTR(error);
 }
 
+/**
+ * gfs2_lookup_by_inum - look up an inode by inode number
+ * @sdp: The super block
+ * @no_addr: The inode number
+ * @no_formal_ino: The inode generation number (0 for any)
+ * @blktype: Requested block type (see gfs2_inode_lookup)
+ */
 struct inode *gfs2_lookup_by_inum(struct gfs2_sbd *sdp, u64 no_addr,
-				  u64 *no_formal_ino, unsigned int blktype)
+				  u64 no_formal_ino, unsigned int blktype)
 {
 	struct super_block *sb = sdp->sd_vfs;
 	struct inode *inode;
@@ -221,7 +228,7 @@ struct inode *gfs2_lookup_by_inum(struct gfs2_sbd *sdp, u64 no_addr,
 	/* Two extra checks for NFS only */
 	if (no_formal_ino) {
 		error = -ESTALE;
-		if (GFS2_I(inode)->i_no_formal_ino != *no_formal_ino)
+		if (GFS2_I(inode)->i_no_formal_ino != no_formal_ino)
 			goto fail_iput;
 
 		error = -EIO;

fs/gfs2/inode.h

@@ -92,7 +92,7 @@ extern struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned type,
 				       u64 no_addr, u64 no_formal_ino,
 				       unsigned int blktype);
 extern struct inode *gfs2_lookup_by_inum(struct gfs2_sbd *sdp, u64 no_addr,
-					 u64 *no_formal_ino,
+					 u64 no_formal_ino,
 					 unsigned int blktype);
 
 extern int gfs2_inode_refresh(struct gfs2_inode *ip);