ext4: convert ext4_getblk() to use the ERR_PTR convention

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3aa26e9..0dfc1cd 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -734,11 +734,11 @@
  * `handle' can be NULL if create is zero
  */
 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
-				ext4_lblk_t block, int create, int *errp)
+				ext4_lblk_t block, int create)
 {
 	struct ext4_map_blocks map;
 	struct buffer_head *bh;
-	int fatal = 0, err;
+	int err;
 
 	J_ASSERT(handle != NULL || create == 0);
 
@@ -747,21 +747,14 @@
 	err = ext4_map_blocks(handle, inode, &map,
 			      create ? EXT4_GET_BLOCKS_CREATE : 0);
 
-	/* ensure we send some value back into *errp */
-	*errp = 0;
-
-	if (create && err == 0)
-		err = -ENOSPC;	/* should never happen */
+	if (err == 0)
+		return create ? ERR_PTR(-ENOSPC) : NULL;
 	if (err < 0)
-		*errp = err;
-	if (err <= 0)
-		return NULL;
+		return ERR_PTR(err);
 
 	bh = sb_getblk(inode->i_sb, map.m_pblk);
-	if (unlikely(!bh)) {
-		*errp = -ENOMEM;
-		return NULL;
-	}
+	if (unlikely(!bh))
+		return ERR_PTR(-ENOMEM);
 	if (map.m_flags & EXT4_MAP_NEW) {
 		J_ASSERT(create != 0);
 		J_ASSERT(handle != NULL);
@@ -775,25 +768,26 @@
 		 */
 		lock_buffer(bh);
 		BUFFER_TRACE(bh, "call get_create_access");
-		fatal = ext4_journal_get_create_access(handle, bh);
-		if (!fatal && !buffer_uptodate(bh)) {
+		err = ext4_journal_get_create_access(handle, bh);
+		if (unlikely(err)) {
+			unlock_buffer(bh);
+			goto errout;
+		}
+		if (!buffer_uptodate(bh)) {
 			memset(bh->b_data, 0, inode->i_sb->s_blocksize);
 			set_buffer_uptodate(bh);
 		}
 		unlock_buffer(bh);
 		BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
 		err = ext4_handle_dirty_metadata(handle, inode, bh);
-		if (!fatal)
-			fatal = err;
-	} else {
+		if (unlikely(err))
+			goto errout;
+	} else
 		BUFFER_TRACE(bh, "not a new buffer");
-	}
-	if (fatal) {
-		*errp = fatal;
-		brelse(bh);
-		bh = NULL;
-	}
 	return bh;
+errout:
+	brelse(bh);
+	return ERR_PTR(err);
 }
 
 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
@@ -801,7 +795,12 @@
 {
 	struct buffer_head *bh;
 
-	bh = ext4_getblk(handle, inode, block, create, err);
+	*err = 0;
+	bh = ext4_getblk(handle, inode, block, create);
+	if (IS_ERR(bh)) {
+		*err = PTR_ERR(bh);
+		return NULL;
+	}
 	if (!bh)
 		return bh;
 	if (buffer_uptodate(bh))