ext4: use ERR_PTR() abstraction for ext4_append()

Use ERR_PTR()/IS_ERR() abstraction instead of passing in a separate
pointer to an integer for the error code, as a code cleanup.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/inode.c

@@ -707,6 +707,8 @@ struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
 	/* ensure we send some value back into *errp */
 	*errp = 0;
 
+	if (create && err == 0)
+		err = -ENOSPC;	/* should never happen */
 	if (err < 0)
 		*errp = err;
 	if (err <= 0)

fs/ext4/namei.c

@@ -51,34 +51,28 @@
 
 static struct buffer_head *ext4_append(handle_t *handle,
 					struct inode *inode,
-					ext4_lblk_t *block, int *err)
+					ext4_lblk_t *block)
 {
 	struct buffer_head *bh;
+	int err = 0;
 
 	if (unlikely(EXT4_SB(inode->i_sb)->s_max_dir_size_kb &&
 		     ((inode->i_size >> 10) >=
-		      EXT4_SB(inode->i_sb)->s_max_dir_size_kb))) {
-		*err = -ENOSPC;
-		return NULL;
-	}
+		      EXT4_SB(inode->i_sb)->s_max_dir_size_kb)))
+		return ERR_PTR(-ENOSPC);
 
 	*block = inode->i_size >> inode->i_sb->s_blocksize_bits;
 
-	bh = ext4_bread(handle, inode, *block, 1, err);
-	if (bh) {
+	bh = ext4_bread(handle, inode, *block, 1, &err);
+	if (!bh)
+		return ERR_PTR(err);
 	inode->i_size += inode->i_sb->s_blocksize;
 	EXT4_I(inode)->i_disksize = inode->i_size;
-		*err = ext4_journal_get_write_access(handle, bh);
-		if (*err) {
+	err = ext4_journal_get_write_access(handle, bh);
+	if (err) {
 		brelse(bh);
-			bh = NULL;
-		}
-	}
-	if (!bh && !(*err)) {
-		*err = -EIO;
-		ext4_error(inode->i_sb,
-			   "Directory hole detected on inode %lu\n",
-			   inode->i_ino);
+		ext4_std_error(inode->i_sb, err);
+		return ERR_PTR(err);
 	}
 	return bh;
 }
@@ -1555,11 +1549,12 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,
 				       EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
 		csum_size = sizeof(struct ext4_dir_entry_tail);
 
-	bh2 = ext4_append (handle, dir, &newblock, &err);
-	if (!(bh2)) {
+	bh2 = ext4_append(handle, dir, &newblock);
+	if (IS_ERR(bh2)) {
 		brelse(*bh);
 		*bh = NULL;
-		goto errout;
+		*error = PTR_ERR(bh2);
+		return NULL;
 	}
 
 	BUFFER_TRACE(*bh, "get_write_access");
@@ -1640,7 +1635,6 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,
 	brelse(bh2);
 	*bh = NULL;
 	ext4_std_error(dir->i_sb, err);
-errout:
 	*error = err;
 	return NULL;
 }
@@ -1815,10 +1809,10 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
 	len = ((char *) root) + (blocksize - csum_size) - (char *) de;
 
 	/* Allocate new block for the 0th block's dirents */
-	bh2 = ext4_append(handle, dir, &block, &retval);
-	if (!(bh2)) {
+	bh2 = ext4_append(handle, dir, &block);
+	if (IS_ERR(bh2)) {
 		brelse(bh);
-		return retval;
+		return PTR_ERR(bh2);
 	}
 	ext4_set_inode_flag(dir, EXT4_INODE_INDEX);
 	data1 = bh2->b_data;
@@ -1950,9 +1944,9 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
 			return make_indexed_dir(handle, dentry, inode, bh);
 		brelse(bh);
 	}
-	bh = ext4_append(handle, dir, &block, &retval);
-	if (!bh)
-		return retval;
+	bh = ext4_append(handle, dir, &block);
+	if (IS_ERR(bh))
+		return PTR_ERR(bh);
 	de = (struct ext4_dir_entry_2 *) bh->b_data;
 	de->inode = 0;
 	de->rec_len = ext4_rec_len_to_disk(blocksize - csum_size, blocksize);
@@ -2023,9 +2017,11 @@ static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,
 			err = -ENOSPC;
 			goto cleanup;
 		}
-		bh2 = ext4_append (handle, dir, &newblock, &err);
-		if (!(bh2))
+		bh2 = ext4_append(handle, dir, &newblock);
+		if (IS_ERR(bh2)) {
+			err = PTR_ERR(bh2);
 			goto cleanup;
+		}
 		node2 = (struct dx_node *)(bh2->b_data);
 		entries2 = node2->entries;
 		memset(&node2->fake, 0, sizeof(struct fake_dirent));
@@ -2364,8 +2360,9 @@ static int ext4_init_new_dir(handle_t *handle, struct inode *dir,
 	}
 
 	inode->i_size = 0;
-	if (!(dir_block = ext4_append(handle, inode, &block, &err)))
-		goto out;
+	dir_block = ext4_append(handle, inode, &block);
+	if (IS_ERR(dir_block))
+		return PTR_ERR(dir_block);
 	BUFFER_TRACE(dir_block, "get_write_access");
 	err = ext4_journal_get_write_access(handle, dir_block);
 	if (err)