ext4: Check for the correct error return from

ext4_ext_get_blocks returns negative values on error. We should
check for  <= 0
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

fs/ext4/extents.c

@@ -2462,11 +2462,11 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
 		ret = ext4_ext_get_blocks(handle, inode, block,
 					  max_blocks, &map_bh,
 					  EXT4_CREATE_UNINITIALIZED_EXT, 0);
-		WARN_ON(!ret);
-		if (!ret) {
+		WARN_ON(ret <= 0);
+		if (ret <= 0) {
 			ext4_error(inode->i_sb, "ext4_fallocate",
-				   "ext4_ext_get_blocks returned 0! inode#%lu"
-				   ", block=%u, max_blocks=%lu",
+				    "ext4_ext_get_blocks returned error: "
+				    "inode#%lu, block=%u, max_blocks=%lu",
 				    inode->i_ino, block, max_blocks);
 			ret = -EIO;
 			ext4_mark_inode_dirty(handle, inode);