nilfs2: treat missing cpfile header block as metadata corruption

The cpfile, a metadata file that holds metadata for checkpoint management,
also has statistical information in its first block, and if reading this
block fails, it receives the internal code -ENOENT and returns that code
to the callers.

As with sufile, to prevent this -ENOENT from being propagated to system
calls, return -EIO instead when reading the header block fails.

Link: https://lkml.kernel.org/r/20240821154627.11848-3-konishi.ryusuke@gmail.comSigned-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/nilfs2/cpfile.c

@@ -125,10 +125,17 @@ static void nilfs_cpfile_block_init(struct inode *cpfile,
 	}
 }
 
-static inline int nilfs_cpfile_get_header_block(struct inode *cpfile,
-						struct buffer_head **bhp)
+static int nilfs_cpfile_get_header_block(struct inode *cpfile,
+					 struct buffer_head **bhp)
 {
-	return nilfs_mdt_get_block(cpfile, 0, 0, NULL, bhp);
+	int err = nilfs_mdt_get_block(cpfile, 0, 0, NULL, bhp);
+
+	if (unlikely(err == -ENOENT)) {
+		nilfs_error(cpfile->i_sb,
+			    "missing header block in checkpoint metadata");
+		err = -EIO;
+	}
+	return err;
 }
 
 static inline int nilfs_cpfile_get_checkpoint_block(struct inode *cpfile,
@@ -283,14 +290,9 @@ int nilfs_cpfile_create_checkpoint(struct inode *cpfile, __u64 cno)
 
 	down_write(&NILFS_MDT(cpfile)->mi_sem);
 	ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
-	if (unlikely(ret < 0)) {
-		if (ret == -ENOENT) {
-			nilfs_error(cpfile->i_sb,
-				    "checkpoint creation failed due to metadata corruption.");
-			ret = -EIO;
-		}
+	if (unlikely(ret < 0))
 		goto out_sem;
-	}
+
 	ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 1, &cp_bh);
 	if (unlikely(ret < 0))
 		goto out_header;